The loading thermal (LT) yield curve is first introduced to consider the effects of temperature on the preconsolidation pressure change for unsaturated clays. Based on the concept of true strength and the calculation method of the potential failure stress ratio, the equation of the critical state stress ratio for unsaturated clays under different temperatures is deduced. The LT yield curve is then combined with the loading collapse (LC) yield curve which is used to consider the effects of suction on the preconsolidation pressure change for unsaturated clays, by which the loading thermal collapse (LTC) yield surface is presented. Therefore, the effects of both temperature and suction on the preconsolidation pressure change are considered by the LTC yield surface. After that, a constitutive model for normally consolidated unsaturated clays considering temperature effects is proposed based on the framework of the critical state soil mechanics; and it is extended to consider the properties of overconsolidated unsaturated clays. Compared with the Barcelona basic model, the proposed model requires only one additional parameter to consider the behavior of the decrease of preconsolidation pressure with an increase of temperature. The proposed model can describe the effects of temperature, suction and OCRs(overconsolidation ratios) on the stress-strain behavior for clays. Model predictions and test results show that heating will cause an increase of the strength for normally consolidated unsaturated clays at a given suction. The overconsolidation behavior decays or even disappears by either heating or wetting for overconsolidated unsaturated clays, consequently, the behavior of softening and shear dilatancy will be decayed

In rock dynamics, one of typical types of loading is impact loading, which can induce the strain rate up to 1×10-1-1×104 s-1. Impact loading can be generated by a dynamic machine, Hopkinson bar testing equipment and blasting, and is used to investigate the dynamic behavior of rock. When rock is subjected to dynamical loading, inertial effect will become significant. Hence the objective of rock dynamics is to investigate the propagation and dissipation of stress waves in rock, the interaction between the stress waves and the joints of rocks, the reflection, diffraction and injection of the stress waves in layered materials. Initial study of rock dynamics in China could be traced back to the early sixties of last century, when the dynamic effect of blasting on the slope stability of Daye Iron Mine was investigated. Comprehensive research for such a subject started in 1965, when State Commission of Science & Technology and National Defense Commission of Science & Technology approved to establish the defense engineering research group, and launched “construction and research for protective engineering” as a key national research program. Through such events, China built up the foundation for its rock dynamics study. In 1987, the Commission of Rock Dynamics, a sub-committee of Chinese Society of Rock Mechanics and Engineering was founded; and this event became the milestone of the further development of rock dynamics. Members of the commission came from universities and research institutions of water conservancy, hydropower, energy, mining, coal, petroleum, railway transportation etc. Organized by the commission, the “National Conference for Rock Dynamics” has been held every two years, making a great contribution to the advancement of rock dynamics research. This paper will introduce the development and new achievements of rock dynamics in China recent 10 years; and it can be divided into two parts, i.e. the past achievements and the future development trends.

An analytical method is derived for the thermal consolidation of a hollow cylinder saturated porous medium with infinite length. In the coupled governing equations of linear isotropic porous thermoelastic medium, the influences of thermo-osmosis effect and thermal filtration effect are introduced. The solutions in Laplace transform space are first obtained and then numerically inverted by Stehfest method. These solutions consider the variable thermal loading and variable mechanical loading applied on the inner and outer pervious surface of the hollow cylinder with time. Finally, the evolutions of temperature, pore water pressure and displacement along radial direction with time are analyzed by a typical numerical example

The stress state and the geometrical structures in rock mass are adjusted during unloading. Since it is difficult to describe the process of stress adjustment, the geometrical structures are used in the present paper to investigate the process of rock mass unloading, and the elastic wave velocity is studied by considering the interaction of geometrical structure and elastic wave. A double-crack structure is employed to make approximate analysis of the elastic wave velocity in jointed rock mass. In the model, the analysis method of interaction within the double-crack structure is used to partly consider multiple scattering between the joints of rock mass, and the linear superposition method between double-crack structures is adopted to analyze the localization effect for defects in rocks. The influence of unloading on the rock bridge is described by the opening displacement and the opening rate of joints, and variation of elastic wave velocity of four different kinds of rocks corresponding to two dominant frequencies, 25 kHz and 1 kHz, is studied under excavation unloading condition. The results show that in the process of unloading, relative acoustic velocity corresponding to 25 kHz and seismic velocity corresponding to 1 kHz are gradually decreased; however, the decreasing degree of acoustic velocity is less than that of seismic velocity. For example, acoustic velocity of highly unloaded rock mass reduces to be 80% of that of the original rock mass, and seismic wave velocity reduces to be 50% of that of the original rock mass. These conclusions are of good guidance for the inspection and evaluation of water conservancy project and railway tunneling construction

Uniaxial compression test was conducted on sandstone with a single pre-existing flaw at various inclined angles. Employing crack propagation measuring techniques and relevant fracture criteria, some conclusions are drawn as follows. (1) The crack initiation angles of the sandstone specimen obtained from both theory and experiments increased with increasing flaw inclined angle. (2) Using a fracture criterion, the appearance of a anti-wing cracks at the tip of the crack of the sandstone specimen was attributed to shear failure. (3) Under uniaxial compression, crack propagation in the sandstone specimen is influenced by the single flaw inclined angle; a small flaw inclined angle it is not easy to crack initiation, while the large flaw inclined angle, allowed easy crack initiation (4) Under uniaxial compression, crack propagation in the sandstone specimen, which was influenced by a single pre-existing flaw, was unstable when the flaw inclined angle was small; and stable when the angle was large. (5) For the sandstone specimen, the average crack propagation velocity for A and B sides of the crack tip decreases with increasing flaw inclined angle.

Based on a three-dimensional elastoplastic constitutive model. for overconsolidated clays, an acoustic tensor and discriminator of bifurcation for strain localization under partially drained conditions are given. The analytical and numerical solutions to the model along different stress paths are resolved. The theoretical analysis shows that, there is no bifurcation occurring at the Lode angles of -30°, 15°and 30° for both single-phase and soil-water coupling two-phase materials. At the Lode angle of 0°, the bifurcation occurs for the single-phase and doesn’t occur for the soil-water coupling under undrained condition; while whether bifurcation occurs is related to the parameter under partially drained condition. There is bifurcation occurring at the Lode angle of -15° for both the single-phase and soil-water coupling. Numerical simulations on a cubic specimen for the bifurcation for the single-phase and soil-water coupling are carried out by use of a nonlinear finite element analysis software ABAQUS with the model being implemented. The numerical analysis shows that, there is no bifurcation occurring at the Lode angles of 30° for both single-phase and soil-water coupling. At the Lode angle of 15°, bifurcation occurs for the single-phase and doesn’t occur for the soil-water coupling under undrained condition; while the time when bifurcation occurs is related to the permeability under partially drained condition. There is bifurcation occurring at the Lode angles of -15° and 0° for both the single-phase and soil-water coupling. Bifurcation of numerical solutions is more likely to occur than that of analytical solutions along the same stress paths.

In order to investigate the mechanism on zonal disintegration within rockmass around deep tunnel under static-dynamic coupling loading, by using the Instron electro-hydraulic and servo-controlled material testing machine, the test of deep tunnel on plaster model subjected to static-dynamic coupling loading is carried out. In order to further analyze the mechanical nature of layered fracture of surrounding rock around deep tunnel under static-dynamic coupling loading, surrounding rock around deep tunnel is regarded approximately as a combination of samples subjected to biaxial static-dynamic coupling loading; and the biaxial test of red sandstone subjected to static-dynamic coupling loading is performed. Experiments indicate that layered fracture of surrounding rock around deep tunnel may occur when the axial stress of tunnel is the maximum principal stress and more than a certain value. Layered fracture of surrounding rock around deep tunnel may also occur when the axial stress of tunnel is the maximum principal stress and the superposition value of axial stress and external disturbance stress is more than a certain value. Larger tunnel diameter may make layered fracture of surrounding rock around deep tunnel occur more easily under the same static-dynamic coupling loading. The larger superposition value of axial stress and external disturbance stress may make more layered fracture of surrounding rock around deep tunnel occur under the same tunnel diameter. The failure mode of statically loaded sample under periodic dynamic load changes according to different static stress states; and fracture surface of sample is generally perpendicular to the minor principal stress direction (in plane of minor principal stress) and tends to agree with the maximum principal stress direction. There is the foregoing stress state in surrounding rock around deep tunnel triggering layered fracture, and then leading to zonal disintegration within rockmass around deep tunnel under static-dynamic coupling loading.

Three mechanical models of diaphragm wall joint, i. e. flexible joint without resistance to shearing and bending, relative rigid joint with resistance to shearing and absolute rigid joint with resistance to shearing and bending, are established based on different effects of transverse stress transferring. In order to choose a reasonable joint for shield working well of Nanjing Weisan-road Yangtze River tunnel, the deformation and mechanical properties of diaphragm wall are analyzed by using above models. The results show that: flexible joint is easy to cause the increase in displacement of diaphragm wall and soil; and finally, leads to increase internal force of supports. Relative rigid joint are able to not only resist the displacement of diaphragm wall, but also decrease stress of diaphragm wall by transferring the stress to the temporary supports and ring beams; Absolute rigid joint may result in diaphragm wall undertake significant transverse and longitudinal moment. By comprehensive consideration, the relative rigid joint is chosen for the working well.

In view of the shortcomings that the influence zone of vertical drain is always assumed to be a circle in the existing analytical consolidation theories for vertical drains; the consolidation by vertical drains installed in a regular triangle pattern with a regular hexagon shape of influence zone was studied. By establishing new consolidation equation and introducing new boundary conditions, the general analytical solutions accounting for variation of soil horizontal permeability coefficient were derived. Then, according to three types of variation patterns of the horizontal permeability, the corresponding solutions were obtained. Furthermore, the influences of three main dimensionless parameters on the consolidation behavior were analyzed, and the obtained solutions were compared with the existing ones. The results show that the greater the size of influence zone or disturbed smear zone is, the slower the consolidation is; the less the ratio of the maximum to the minimum horizontal permeability coefficient of soil is, the faster the consolidation is; under the same conditions, the consolidation of pattern two considering a linearly changed permeability coefficient within the disturbed zone is the fastest and the solutions of pattern one considering a constant permeability coefficient within the disturbed zone are very close to the existing analytical ones, which indicated that the assumption that the influence zone of vertical drain is a circle adopted in the existing theories is reasonable

The disturbance and damage induced by excavation and blasting, especial blasting cumulative damage effects resulted from frequent blasting, will play down the integrity of rock mass, weaken the mechanical parameters of rock mass and threaten the stability of rock engineering surely. Considered the blasting cumulative damage effects of rock mass, the shortages of Hoek-Brown criterion and its modified expressions were pointed out. The methods of obtaining the value of and s which could reflect the blasting cumulative damage effects, blasting disturbed state and the lowering degree of its mechanical parameters, were found by introducing integrity coefficient and damage factor D. The cumulative expanded models of rock mass blasting damage were found with the baseline of rock mass sound velocity reducing ratio and the models were used in the amended expressions of Hoek-Brown criterion, based on the relationship between sound velocity variation and blasting cumulative damage effects. The analysis of the amended expressions was carried out based on the simulative blasting tests in-situ and the data of sonic measurement. The research results show that the amended expressions of Hoek-Brown criterion taken blasting cumulative damage effects of rock mass into account are reasonable.

Hollow cylinder samples tests were performed with high-density saturated silt from the sea entrance of the Yangtze River. The stress paths consisted of undrained cyclic principal stress rotation at the range of 180° with different shear stress ratio and frequency. It is found that isotropic consolidated samples would liquefy after cyclic principal stress axis rotation, which is featured by the excess pore water pressure reached initial effective confining pressure. Before the liquefaction, due to the different shear stress levels the development of pore water pressure was divided into three stages by graded phase transformation point and cataclysmic phase transformation point or two stages by cataclysmic phase transformation point. As for the development of strain components, it was divided into two stages by collapse point. Meanwhile the cataclysmic phase transformation point of pore water pressure and the collapse point of strain occurred simultaneously, which reflected the state of structure collapse. Besides the deviator strains when the collapse state occured were limited within a narrow range of 0.2%-0.4%. The stress state of collapse can be normalized in - space with a line when samples underwent cyclic principal stress axis rotation after isotropic consolidation. Furthermore the development of pore water pressure can be fitted well by modified Seed model in which the collapse state was used as the normalized denominator.

By model test, the stress distribution of anchored rockbolts close to working face is studied when subjected to blast loading. Based on similar condition, simplification and hypothesis, engineering cutting blasting was simulated in mass charge. Axial strain waves measured from strain gauges mounted on rockbolts were recorded considering both of end-anchored and full grouted rockbolts. Test results show that rockbolt vibration approximately ceases after duration of 6 ms and then bolt deformation keeps stable in 9 ms. For end-anchored bolts, peak stress on middle locations of bolts in anchor section is slightly greater than the value of tail location in smooth section when bolts are subjected to blast loading; but the latter presents a greater residual stress. For full grouted bolts, peak stress and residual stress measured on tail section exceed the values on central section. Utilizing displacement potential function of the infinite body under single force, distribution of axial stress on anchoring body and surrounding rock is theoretically deduced; and additive axial stress on anchored section is calculated under some prestress. Based on the state of additive axial stress and dynamic stress, stress condition of rockbolt is analyzed.

Natural gas hydrate is one of the most important potential energy sources distributing in the seabed and continental permafrost; at the same time, the dissociation of hydrate in hydrates bearing layers is a triggering factor of global climate change and geologic hazards. The method and apparatus for formation sample is a basic issue for researching on hydrates-bearing sediments(HBS), which require homogeneity of the sample according with in-situ formation mode as soon as possible. Most marine hadrate formed in diffusion system, which means the gas transfered to the hydrate occur zone by diffusion in water and formed hydrate.Gas-bearing water is moved in cycles by constant-flow pump in this method and apparatus; and gas solubility in water is enlarged through stirred by magnetic stirring apparatus; soil sample could be saturated with gas-bearing water in short time; and then reduce the temperature of soil sample, Gas dissolved in water associates with water to form hydrate filling in the pore of soil sample equably. The experiments show that 1 day is spent to form the hydrates-bearing sediments used by silt and CO2 sample. Homogeneity is testified through observing and testing water-contents of different positions in formed sample. Thereby , heterogeneity caused by hydrate distribution in pore of sample and cost time too long is dissolved well; technological basis is provided for physico- mechanical experiments of hydrates bearing sediments.

It is necessary to study bedding rock landslides induced by “5•12” Wenchuan earthquake. According to the similar relationship of dynamic model test, a bedding model slope is built with a height of 1.6 m, length of 1.75 m, width of 0.8 m and a slope angle larger than the dip angle of the rock stratum. A large-scale shaking table test of the model slope is performed. The results show that amplification coefficients of the acceleration along slope surface and in vertical direction increase with the elevation increasing. And its increment speeds also increase with the elevation increasing. At the same elevation, the amplification coefficients of the acceleration on slope surface are larger than that in slope body. The input frequency of seismic waves has obvious effects on dynamic responses of slope. The amplification effect of acceleration enhances evidently with the frequency increasing and approach to the natural frequency of the model slope. The amplification coefficients of the acceleration decrease with the earthquake amplitudes increasing. Comparing with the acceleration monitoring data obtained by the shaking table test of the homogeneous slope, it is found that structural surface of the slope also has effects on the amplification coefficients of the acceleration. Because of reflection and refraction of structural surface, the amplification effect of acceleration enhances evidently. Based on analysis of failure features of the slope, the failure process is described as earthquake induction-loosening of rock mass and tensile failure of the crest of the slope-propagation and coalescence of cracks in the middle part of slope surface-occurrence of high locality landslide-formation of debris flow-accumulation at the slope toe. The study results are helpful to reveal the formation mechanism of landslide under earthquake and provide valuable references for disaster prevention and reduction.

It is of great significant to study the bearing behavior and the design procedure of geosynthetics beneath highway embankment built in karst terrain as a treatment to sinkhole. Firstly, the load and load transfer in geosynthetics are investigated according to its characteristics; and the Terzaghi’s soil arch theory in ideal soil is introduced to evaluate the upper load. The strain in geosynthetics and anchorage length are considered as two key design values, which are related to pull-out length at tip of anchorage segment. Then, the linear elastic-fully plastic model is introduced; and the corresponding analytical solution is deduced by the basic equation. The calculating procedures of the lengths of pull-out and load transfer are established by combining the boundary conditions. Based on these, an example in engineering practice is analyzed with its parameters; and the result calculated by proposed method is compared to that calculated by the method based on fully plastic model. The errors influenced by the width of the hole, the stiffness of the geosynthetics, the height of the upper soil, the friction angle on the interface of the soil and the geosynthetics are studied; and the relationship between the length of load transfer and the height of upper soil is investigated as well. The results indicate that, both the length of pull-out and that of load transfer calculated by the method based on the fully plastic model are larger than that by the proposed method; and the error of the length of load transfer is over 40% in some cases. The design base on the fully plastic model may cause unsafe of engineering.

In order to research a new type of geotechnical material——light weight sand, its deformation and strength characteristics were researched by triaxial test. The results show that light weight sand have different primary structural strength because of different mixed ratio and age, soil samples of different primary structural strength are in the state of shear dilatancy or shear contraction under different confining pressures, these lead to strain hardening, strain softening, and three corresponding pore pressure states. Deformation modulus decreases linearly with increase of EPS(expanded polystyrene beads) mixed ratio, increases linearly with increase of cement mixed ratio and age; and there is little relation between deformation modulus and confining pressure for the same mixed ratio soil samples. Triaxial compressive strength decreases according to negative exponential relation with increase of EPS mixed ratio, increases linearly with increase of cement mixed ratio, age and confining pressure. There is a threshold for cement mixed ratio. Transformation effect of soil framework has an important effect on soil strength, and that leads to strength zoning under uniaxial and triaxial compression states. When cement mixed ratio reaches to a high value, it can weaken transformation effect of soil framework of EPS beads. Combining precursors’ research production, influence factors of density and uniaxial compressive strength of light weight sand are researched; then the concept of specific strength is recommended. Prescription of light weight soil-sand can be optimized by combining unit price-specific strength figure and recipe formula. Stress-strain relation transformation of light weight soil-sand is researched, uniaxial compressive strength is recommended to be metewand of primary structural strength. The relation between critical confining pressure and primary structural strength should be built according to test and mathematical statistics; these can make contribution for numerical simulation and establishment of constitutive model.

Taking Na-bentonite as filling medium and cement mortar as fissure wall, the filled fractures are made. By means of normal compression and lateral restraint, the constitutive relations of filled fracture with expansive medium and under the conditions of different fracture widths and different water contents, are discussed. A large number of stress-strain data are obtained. It is shown that the fractures filled with expansive medium can be divided into three stages: rheological phase, compression phase and the elastic stage in the pre-peak. At the beginning of the experiment, the filled fracture is in the rheological state; that is to say, the stress nearly remains unchanged, but the strain continues to increase. With the finite deformation and the normal stress increase, the filled fracture overall intensity increase, and demonstrate elastic characteristics gradually. Based on the results, the mechanical model of inverted Saint-Venant body is put forward; pre-peak constitutive equation of filled fracture with expansive medium is established; and its mechanism is analyzed.

Based on the measured single deck blast vibration signals, time frequency characteristics were analyzed of the superposition signal of the single deck signals with various features by MATLAB programming, and, through introducing the concept of amplitude reduction ratio and vibration velocity ratio, the variation law of characteristics of the superposition signal in millisecond blasting with the delay time, detonating sequence and properties of the seed-signal is put forward. It is found that time difference of the superposition signal arriving at a certain amplitude reduction ratio is not a specific moveout point but many intermittent time difference sections. Meanwhile, dominant frequency variates in a step sawtooth pattern with the difference of the delay time. Under rational millisecond time, the more similar the vibration characteristics of two seed-signals are, the more evident the interference vibration reduction effect is. If charge weight is designated, vibration reduction effect is much better when the segment with small charge quantity is detonated prior to others. And the measured test data in site reflect that the research results basically accord with the practical operation laws of millisecond blasting.

The dynamic properties of intact sandstone samples subjected to axially cyclic loading under confining pressures conditions in the laboratory are presented. Five sets of confining pressures, 10, 20, 30, 40, 50 MPa, were employed by MTS-815 Rock and Concrete Test System. Tests were conducted on dry sandstone samples obtained from areas near “5•12” 2008 Wenchuan Earthquake location with axial loading frequency of 1 Hz and different amplitudes corresponding to different confining pressures. Results demonstrate that: (1) With increased confining pressure, the residual axial and volumetric strain of the rock samples and the residual volumetric strain when dilatancy occurred both become larger. (2) The rock samples subjected to dynamic cyclic loading responded with a significantly higher initial strength and stiffness at higher confining pressures than at lower confining pressures; and the stiffness decreased more rapidly at lower confining pressures than at higher confining pressures. (3) When the stress ratio (Rs) is larger, the sample failed after fewer cycles under confining pressure conditions. (4) The failure modes of the samples are shear failure and the localized band is wider upon dynamic loading.

In embankment projects, the geosynthetics have been widely applied to reinforcing their soft grounds; but the calculation methods still have some shortcomings. The paper made a study from the aspect of limit analysis theory; the slip line method was adopted to improve the upper-bound theorem of limit analysis and deduced a new limit analysis method of ground. When the destructive width of embankment was regarded as a variable, this paper solved the ultimate height of the embankment based on the deduced formulas. The calculated results of the ultimate height agreed well with the measured ones, as the comparison and analysis of project cases showed. The results provide a new efficient way for the design of soft ground embankments.

The optimal composite anchorage structure is constituted by soil nail and groups of fixed-length empty holes that regular setting in the end of soil nail. Empty holes caused a weakened zone in the surrounding rock. The weakened zone is between the reinforced support structure and the surround rock. It changes the original two-medium system into three-medium system. Under the explosion condition, weakened zone is firstly deformed, cracked, crushed or densified; and at the same time, a great deal of blast energy is absorbed. Therefore, the crisis of the reinforced support structure is transferred into the weakened zone. The optimal composite anchorage structure has excellent blast-resistance. The test results of the compression test of optimal composite anchorage structure and single anchorage structure show that the particle acceleration of single anchorage structure is 2.22 times higher than that of the optimal composite anchorage structure. The dynamic strain of the former is 5.30-4.50 times higher than that of the latter. The blast-resistance of the optimal composite anchorage structure is 5.10 times higher than that of the single anchorage structure. Under the limit damage condition, the former is 4.13-3.40 times higher than that of the latter

Dynamic caustics experimental technique is used to study dynamic characteristics of the propagation of explosion main cracks and branched cracks under blasting stress wave. The prefabricated cracks were opening or closing as a result of the explosion stress wave reflection from these cracks, and reduced the dynamic behaviors of explosion main cracks. These main cracks can’t generally pass through the prefabricated cracks and continue to extend. The branched cracks are derived from the ends of the prefabricated cracks. The initiation and propagation of branched cracks are caused by the diffraction effective of tensile stress concentration of the prefabricated crack tips. The split angles of branched cracks are closely related to the prefabricated cracks and angle of blasting incidence stress wave. The branched cracks initiation is started from the direction of generalized maximum energy release rate, and shown as mixed mode fracture and the stability propagation with the direction of maximum principal stress. The dynamic stress intensity factor and velocity of branched cracks are lower than blasting main cracks’. The initial fracture toughness of branched cracks is about 0.5-0.65 MN/m3/2. The arrest toughness of branched cracks is about 0.25-0.35 MN/m3/2

Some existing state-dependent mathematic models for compression curve of cohesionless soils are described and analyzed briefly. Isotropic compression tests on sand with different initial densities are performed. On basis of the results, a new state-dependent stress-strain model for cohesionless soil under hydrostatic compression is proposed. The model is able to describe well stress-strain behaviour which develops throughout first loading and can be adaptable to different freshly deposited cohesionless soils subjected to isotropic compression over a wide range of stresses and densities. The model parameters can be determined simply and conveniently from isotropic compression test. Comparison with experimental data of four types of sands indicates that the model can gives excellent predictions to the measured isotropic compressive behaviour; and it can be used to construct generalized state-dependent constitutive models.

Based on the unified strength theory, a new formula of critical edge pressure and critical load of subsoil considering the effect of intermediate principal stress ?2 and the static lateral pressure coefficient is deduced. After contrasting the results of the unified solutions with those based on the Mohr-Coulomb criterion, it is shown that this method can reflect the essentials of foundation bearing capacity more accurately and be conducive to make full use of the strength of foundation. A thorough study of the intermediate principal stress coefficient b has been made through statistical analysis for 177 groups of soil indices and the loading test data of different foundation soils in Hebei province. The result proves that the value of b changes from 0 to 0.50 for the silt and clay soil foundation; and the relative error between the theoretical values of the foundation bearing capacity and the measured values of loading test is generally less than 5%.

Previous experiences in existing engineering are often referenced in designing a new engineering. Restricted by the limited data of free fields of rocks under chemical explosions, a unified equation has not been suggested in designing codes for protective structures. A weighted least squares fitting method is suggested as an effective method to predict the free field in rocks. The weighted factors were defined according to the similarities of the engineering, including mass of explosive, rock quality and wave impedance. According to several empirical equations and the suggested method, a modified equation for free fields in rocks is built and discussed.

Compacted clay liner is the barrier material for landfill; and its thickness and permeability coefficient are important for design. Based on performance design and probabilistic method, the effect of design parameters on contaminant relative concentration and flux at base of liner is analyzed. The variability of permeability coefficient is very significant for the performance of liner. The probability of high concentration (close to 1) at base of liner is large, even the mean concentration is relatively low. This is a big threat to environment, which can’t be reflected through deterministic method. From the probabilistic perspective, the requirements of thickness and permeability coefficient for liner are reasonable. Relative to the flux at base of liner, the relative concentration is more sensitive to thickness of liner and should be used as the key indicator for performance evaluation of liner.

According to statistics, the eighty percent of water inrushes and submerged well accidents were induced by the faults in China. Most of them were induced by the fault activation affected by the workface advanced in non-water-transmissible faults under the condition of original geology. Owing to the need of safe production and water-preserved mining, the activation and water inrush of faults in overburden rock due to the advance of workface were analyzed with mechanics. The mining methods of both preventing fault activation water inrush and water-preserved mining were researched. The fault activation criterion was deduced by the Mohr-Coulomb failure criterion. The calculating formula of critical obliquity and the critical mining depth of the fault activation were deduced. The calculating formula of critical advanced distance was deduced in activating of the fault for the interval mining method adopted. The results show that the failure form of the fault has prodigious relation with the obliquity of fault. With the increase of fault obliquity, the failure form of fault show successively: simultaneity failure of the fault with overburden rock in advancing of the workface, shear failure and tension failure. The more the increase of fault obliquity becomes, the easier activation of fault becomes. According to research result, the critical advanced distance was calculated when the interval mining method adopted, following the example of water-preserved mining at Daliuta mine. The calculated result was validated by the use of a similar simulation.

The shear slippage failure theory is used to study the stress-strain state in terrane ahead of working face; and then the main factors that cause volumetric deformation are analyzed. By means of the volumetric deformation state and its consequences, the mechanism of zonal disintegration phenomenon is explained and the occurrence conditions are derived. The results show that the main reason for volumetric deformation in supporting zone of deep rock mass is that the different pressure in prime stress space leads to the rock mass’s spalling, which explains the zonal disintegration; meanwhile, according to the characters of the shallow or deep rock engineering, the computation formula containing the column strength of rock mass is used to define the shallow or deep rock engineering. As to the thin rock terrane, the Prandtl solution is a good approximate one.

Numerical manifold method (NMM) is a numerical system which contains manifold method, finite elements and discontinuous deformation analysis (DDA). NMM can return to finite elements when physical elements and mathematical elements in NMM are superposition completely; and contact theory is removed. It will be verified by plate compression numerical experiment in the paper. In previous NNM, the problem of mass-conservation is neglected, which the weight of the physical elements will change with changes in its volume; so there are certain error in the calculation results. Mass-conservation can be realized by changing the elements density in the process of calculation; that will perfect the theoretical basis of numerical manifold methods.

In order to raise the reliability and convenience of calculating settlement, a practical method for calculating settlement based on actual stress path is proposed. According to stress path method, a practical expression for calculating settlement is put forward by using effective stress path equation derived from Skempton pore water pressure equation, which has the advantages of explicit conception and simple form with the parameters of expression easy to be obtained. An engineering case study shows that the proposed method is reliable; it can be taken as a reference for engineering applications.

Seismic safety of high fill subgrade presents a difficult design problem, constituting one of the greatest challenges in the development of highway in West China. To study the seismic damage and dynamic characteristics of fill subgrade, firstly the fill subgrade seismic damage of Wenchuan Earthquake is investigated finding out that the main seismic damage type of fill subgrade is rip of upside and bulge of downside. The seismic response and damage of fill subgrade was studied through a shaking table test. In order to model the main factors that influence the seismic response, the model system included the dynamic interactions between the subgrade and retaining wall, construction progress, boundary conditions, etc. The model is made of red beds and quartz sand, meets the requirement of similitude. Results show that the subgrade slope has amplification effort to input seismic waves; and the effect becomes extremely prominent around the crest of the subgrade. The study also shows that the top of the retaining wall and the crest of the subgrade are the vulnerable parts of subgrade and cracks normally appear near these parts under seismic motion. The dynamic characteristics of the subgrade as well as its weak portions during earthquakes are discussed, so as to provide valuable references for seismic appraisal of subgrade.

Complicated material fabrics are the main factors to control the mechanical characteristics of rock mass; currently the anisotropic problems caused by structural planes are the most hot topics. As a special structure rock mass, the discontinuity and anisotropy of rock mass with columnar joints is very typical. The microstructure can be represented by a second order tensor whose eigenvectors specify the orientation of the axes of material symmetry, which is an effective new method to study structure plane caused anisotropy. Microstructure tensor and loading direction are important parameters for this theory. With projection relation of multiple joint surface between spatial local coordinate system and integral coordinate system considered, microstructure tensor is derived. Using ψ describes the projection of the microstructure tensor on the loading direction. The modified anisotropic failure criterion, which incorporating a microstructure for columnar joints based on Jaeger proposed for failure along the material fabrics, is used to study anisotropy of the multiple joint surface. Meanwhile, we use it to consider the Baihetan hydropower station columnar joint- project and analyze columnar joint anisotropy caused stability problem.

At present, the common methods for evaluating consolidation coefficient are the logarithm of time and the square root of time methods, both of which are graphical methods. In these two methods, there are some large influences of the man-made factors during graphical construction. The relationship between settlement-velocity of arbitrary moment and settlement-velocity of next moment is developed based on the one-dimensional consolidation theory, which provides a new method for evaluating consolidation coefficient by analyzing the measured data with the least square method. Then the rationality of the new method is verified through project cases study; and the results indicate that the new method can determine the consolidation coefficient with high accuracy and convenience to use. In addition, when the new method is adopted for evaluating consolidation coefficient, the latter measured data after an hour is not necessary, which means that the process of consolidation test can be accelerated.

The effect of deep excavation on piles beneath the excavation bottom should not be ignored. Based on the verified finite element parameters of a project in Tianjin, load tests with sleeve and under excavation of piles with different lengths are analyzed. The characters of load transfer and settlement of piles designed by conventional pile load tests are analyzed in deep soft soil region. From the finite element analysis results, some conclusions are drawn as follows. The shaft resistance and tip resistance of piles beneath the excavation bottom are mobilized asynchronously. The tip resistance ratios are almost zero under working loads for piles longer than 40 m. The shaft resistance distributes in a ‘R’ pattern. There are even tensile forces in the lower part of piles under working loads. The friction on the lower part is negative for piles longer than 80 m. The settlement calculated considering shaft resistance distribution influenced by excavation is closer to observed data than that of Geddes solution.

In order to research the supporting methods for deep rock roadway with broken and soft surrounding rock in coal mines, this article analyzed the deformation pattern of the deep rock roadway basing on the engineering background of level -780 m south wing rail roadway of Guqiao Coal Mine, Huainan mining area. Comparing with the shallow rock roadway, the difficulties as well as methods in supporting deep rock roadway were analyzed; and afterwards, Sub-step supporting method and optimized supporting method for south wing rail roadway of Guqiao Coal Mine were raised. Monitoring data show that sub-step supporting method is successfully used in the level -780 m south wing rail roadway of Guqiao Coal Mine. The following ideas were raised, deep rock roadway is affected by multiple factors, such as ground pressure and physical features of the rock mess. Supporting methods should consider geological conditions and make all of the supporting measures to achieve effective integration so as to enhance the self-supporting capability of the surrounding rock

The best valid breaking force on the rock mass is very weak, but the impeding force on the rock mass is quite strong under free-face blasting condition. Then blasthole stemming length has a great impact on the blasting vibration. Therefore, it is important to study the stemming length effects of single free-face blasting vibration characteristic. This paper carry out small scale experiment of single free-face blasting with different stemming lengths, and simulate the blasting process. It reveals that the velocity of the vibration due to blasting decreases rapidly in the near field and slowly in the far field. The values of site coefficient K and attenuation coefficient ? increase with the increase of the stemming length. The error of simulated and measured vibration vilocity is less than 15%. The bottom of stem cavity radius of models with different stemming lengths is almost equal; and the cavity radius is about three times for the charge radius. The optimal of stemming length is 15-20 cm in this experiment, non-stemming blasting has greater effect on the effective stress field at the upper blasthole but less effect on the effective stress field at the bottom under the same conditions.

Tunnel boring machine(TBM) should face the risk of very strong rockburst directly in intact and brittle rock mass section with ultrahigh stress concentration for full-face excavation in deep tunnel; then safety of equipment and personnel will be under great threat. The excavation test through “part-pilot heading + TBM” is carried out in the diversion tunnel #3 of the Jinping II hydropower station and the rockburst risk of TBM part-pilot excavation is researched via real-time microsesimic monitoring. The results show that: (1) The daily number of microseismic events, the daily accumulative radiated seismic energy, number of big events and frequency and strength of rockburst in the field during part-pilot excavation are far lower than in the period of full-face advance. (2) The time domain evolution of logarithm of energy index and accumulative apparent volume indicates that the risk of strong rockburst in part-pilot section is smaller; and the excavation in field also proved this. (3) In comparison to full-face advance, the degree of concentration, number, magnitude and radiated energy of microseismic events in space in section of part-pilot are far lower. Therefore, the rockburst risk of TBM for part-pilot driving is more less than for full-face advance. In very strong rockburst section, when construction condition is indispensable, the part-pilot can be excavated in advance and then TBM pass, the risk of rockburst can be controlled availably.

The traditional GM (1, 1) model was not high accuracy and strong adaptability for deformation forecast, the paper improved traditional GM (1, 1) from multiple angles, and integrated the traditional GM (1, 1) and its improved models, established prediction model base. By using gray evaluation model to evaluate the prediction results of model base, so that the intelligent prediction was achieved; and the forecast model base and evaluation model were achieved-by using programming language. Finally, the model base was test by Pangushan Tungsten Mine deformation data; the result indicates that the model base can predict the different characteristics of data and intelligently get the best prediction results; and has important application value

The slot-cut method is put forward, aiming at the problem of frequent rockburst for hydropower projects in Southwest China. The mechanism and method of slot-cut prevention of delayed rockburst are discussed by theoretical analysis, numerical simulation, and construction technology. The existence of slots provides extra space for circumferential deformation, thus decreases the circumferential stress on the surface of surrounding rock mass. The plastic strain formed on the slot bottom and between slots absorbs part of the elastic strain energy stored in the rock mass. It’s revealed by the numerical analysis that the location, spacing and number of slots should be arranged reasonably for better prevention effect. In actual practice, the slots-cutting operation should be well designed, for more accurate control on the dimensions of slots, and can be accomplished by drill-blasting or accumulative explosives pre-split blasting.

Through analyzing the existing definitions of damage variables, we try to use the fractal dimension as a characteristic of the rock damage variable and establish the relationship between fractal dimension and damage degree. According to the calculation method of box-counting dimension and digital image storage principles, to compile the simple digital image of a box-counting dimension algorithm based on Matlab. Combining with practical project of blasting, the digital panoramic borehole camera system is taken for field-test. Through extracting the crack from images of the before explosion and post-explosion of blasts rock, then some graphics processings are made to get the fractal dimensions corresponding to cracks. Finally, damage increments under the action of blasting are determined. The results show that the using fractal dimension to describe the damage of rock, overcomes the disadvantages of other definition methods which involve too much rock characteristic parameters, so as to explore a new way to study the damage degree and evolution process of rock damage.

It has been well documented that the mechanical behavior of naturally structured clays is different from that of remolded clays due to aging during depositional and post-depositional processes. However, the effect of soil structure on secondary consolidation is still seldom investigated. A series of oedometer and secondary consolidation tests were performed on both undisturbed and remolded samples of Lianyungang marine clay to investigate the secondary consolidation behavior. The results show that the secondary consolidation behavior changes dramatically in the vicinity of the consolidation yield stress. When the consolidation pressure is less than the consolidation yield stress, the creep can be neglected. However, the coefficient of secondary consolidation Cα, increases dramatically in the vicinity of the consolidation yield stress. Then, Cα decreases with the increase in consolidation stress. It is also found that the coefficient of secondary consolidation is a function of the ratio of t over tp and compression index. A method for calculating the secondary consolidation deformation is also proposed based on the above relationships. The data compiled from available literature were used to verify the effectiveness of the proposed method.

Compacted soil, which widely exists in many sorts of engineering projects, is commonly unsaturated soil; and its physico- mechanical characteristics are influenced by soil moisture. Because of the difficulty in matric suction measurement, it is hard to apply the unsaturated soil strength theory to compacted soil projects. This paper aims to research how much influence on shear strength of compacted soil when soil moisture varies, and tries to find an easy and useful way in determining the shear strength of unsaturated compacted soils. Research works start from the theory of unsaturated soil, and the mechanism, with which soil moisture affects shear strength of compacted soil, is analyzed. Triaxial shear test results of five sorts of unsaturated compacted soils are rearranged and analyzed; and strength parameters of direct shear test are collected and arranged from data of some filled and compacted soil projects. Analysis shows that matric suction contributes a considerable portion of shear strength in the compacted soils; and the influence of soil moisture on shear strength of compacted soil is obvious and can not be neglected. A fine linear relationship between logarithmic saturation and cohesion of compacted soil is found in project data; and a simple method for calculating shear strength of compacted soil, which can take saturation degree influence into account, is presented

The present safety factor of pile foundation judges the safe characteristic of pile-soil system integrally; but the mechanical character of pile is not clear for the end resistance and side friction of pile by using this safety factor. So, based on the bearing mechanism of end resistance and side friction of pile, and different proportion of two resistances to the total bearing capacity, the safety reserve factor of end resistance ( ) and the safety reserve factor of side friction ( ) are put forward; these two different safety reserve factors (SRFs) are objectively judged by strength reduction of nonlinear limit analysis FEM. The inflection points of - curve and - curve, and the previous reduction-factors on the sharp point of V type of - curve and - curve are estimated as the safety reserve factor of end resistance and the safety reserve factor of side friction under the load condition. The analysis of FEM shows that the results of two reduction-factors method are near to the results of static load tests, the load increment method and a safe reserve factor method when the strength parameters of ground (c and ) near to real parameters; and these inflection points of - curve and - curve, and the sharp point of V type of - curve and - curve have the specific physic purport; and the safety reserve factors of pile-soil system (F) by two reduction-factors method are close to the safety reserve factors of single reduction-factors method; and double safety reserve factors of and have some practicality in practice engineering.

Dynamic failure of quasi-brittle materials under dynamic loading has been a hot issue; the direction of crack propagation of pre-cracked specimens with mode II crack subjected to impact shear loading is closely related to its mechanical properties and impact velocity. The numerical simulations of dynamic shear crack propagation in specimens with two parallel edge pre-notches subjected to impact loading were carried out to investigate the propagation of mode II crack using rock failure process analysis-dynamic code. The effects of material properties, material heterogeneity, incident stress pulse amplitude and duration on the mode II crack propagation path were also investigated. The numerical results show that the mode II crack propagation under impact loading is induced by the shear damage as well as the tensile damage. Microcracks around main-crack are due to the material heterogeneity, which in turn influences the crack bifurcation and associated stress fields around cracks. Crack branching occurs and the specimen is further damaged when stress amplitude and duration are respectively beyond a certain value. The study result is of great help to investigate the law of mode II crack propagation and reveals the mechanism of damage and fracture of quasi-brittle materials under impact loading.

Further analysis is performed on hydro-mechanical-damage coupled creep constitutive model of mudstone proposed by authors in part one. Based on the continuum damage mechanics and Biot theory, the finite element equations of creep damage model are derived by considering the hydro-mechanical-damage coupling. The four-step numerical framework, i.e., elastic predictor-plastic corrector-damage corrector-permeability corrector, is provided. A nonlinear finite element analysis program is developed by the above algorithm. Based on the in-situ monitoring results of lining deformation for about 20 years, the unknown parameters of mudstone are acquired by the method of displacement back analysis. Considering the actual case of the construction of the Test Drift of radioactive waste disposal in the deep Boom mudstone formation in Belgium, the hydro-mechanical coupling process, the evolution of damage and the long term stability of the surrounding rock are studied by the proposed models. The results show that the permeability of excavation damaged zone is 120 times than that of the original mudstone after excavation. Because of the self-healing of fractures, the permeability of excavation damaged zone changes obviously and tends to self-heal with time because of the stress-water action. About 3.5 years later, the permeability of the surrounding rock is near original mudstone. The creep damage increases rapidly in the early stage and tends to stabilize gradually with time. Damage of middle part is larger than that of bottom and top part of the surrounding rock. The study can be used for predicting the long-term stability of tunnel engineering.

It can not only play a guiding role in engineering design in advance predicting the cracking depth and damaged range of surrounding rocks by blasting excavation in use of numerical simulation method, but also is of great significance to construction safety; in which, a scientific and reasonable damage model and iterative calculation method are most important key technique. Based on the user-defined constitutive modules of the fast Lagrangian analysis of continua in three dimensions (FLAC3D) procedure, Yang-Liu dynamic damage model dependent on strain rate considering cumulative strain and load time is embedded in Mohr-Coulomb elastoplastic model. The rock damage characteristic is reflected in the iteration calculation process of a incremental load; thus an elastoplastic dynamic damage constitutive model is formed. Subsequently, iterative format of damaged and modified stresses is derived in detail. In simulating a circular tunnel by blasting excavation, a discussion and analysis for characteristics of vibration attenuation and distribution rules of damage in surrounding rock mass induced by blasting are carried out. The calculation result shows that the vibration velocity peak is well correlated with the damage coefficient. The blasting damage model and simulation method can provide a certain reference to similar engineering.

The numerical simulation test is performed for validation vibration isolation function of liquefaction. A gravel drainage layer is applied around underground structure; the anti-liquefaction numerical simulation tests of gravel drainage layer were performed using FLAC3D. Anti-liquefaction effect of the different gravel drainage layer programmes is analyzed; and dynamic characteristic change of underground structures after imposition a gravel drainage layer in liquefaction field is also analyzed. Calculations indicate that when the sandy soil is in the liquefied condition in the model liquefaction field, its acceleration, the speed, the displacement oscillation amplitude weaken immediately. The sandy soil becomes the fluid in the liquefied condition. The liquefaction process is the process which the sandy soil volume pressure strain accumulates unceasingly. The volume pressure strain accumulation no longer increases after the sandy soil is liquefied. The effective stress of liquefied soil is zero. The shearing strength is zero. The liquefied soil cannot transmit the shearing force and isolates outside force. The acceleration of structure in liquefied field is also smaller than the non-liquefied field or the elastic field. The structure, which is in the liquefied field, reduced the hydrodynamic pressure around structure. The structure interrupted the liquefaction around structure. The gravel drainage layer around underground structure will not be liquefied. The ultra hydrostatic pressure in distant place liquefied field reduces obviously. The structure is not floating, the structure subsided. The horizontal drift reduced. The internal force increased. Research results will provide a theoretical and experimental basis for the design of underground structures through the liquefied soil layer.

Based on the principle of in-situ transient pulse technique and its solving method, the small size in-situ transient pulse permeability measurement system, including data acquisition control system, pulse applying system, and permeability measuring system, has been developed successfully. Due to its simple configuration and small size, it is easy to control and use to measure the permeability of low-permeable in-situ confining rocks rapidly, which are often studied in geological disposal of radioactive waste，underground gas and oil storage tanks and construction of deep cavern groups, etc. Moreover, other kinds of rock mass within narrow surrounding spaces or serious disturbance requirements also can be measured. The small size in-situ transient pulse permeability measurement experiments have been introduced in this paper by using this system, of which the applicability, stability and accuracy have been proved.

The brilliouin optical time domain analyzer (BOTDA) is a new distributed optical-electronic sensing technique successfully developed abroad. It had been widely applied to detecting temperature and strain of structures. The new distributed strain measuring technique, pulse-prepump-brilliouin optical time domain analyzer (PPP-BOTDA) method realizes the test results of 10cm spatial resolution and ±7.5 με strain measuring precision. This paper describes the basic principle and experimental results of PPP-BOTDA, And its strain measuring method has been firstly applied to the tubular pile test; at the same time, a contrast with the sliding micrometer results is done; and it is shown the PPP-BOTDA is a very potential technique for the pile test.

The virtual extensometer is developed based on digital speckle correlation method (DSCM). To realize the virtual extensometer, the cracks on the specimen are firstly identified and located using the strain fields measured by DSCM. Then, virtual extensometers are installed on the cracks. Finally, the opening and the dislocation of the cracks are calculated through the displacement fields. The principle and realization of the virtual extensometer are introduced. The reliability of virtual extensometer is verified by a specially designed experiment and the resolution of virtual extensometer is calibrated as 0.1 pixels. This virtual extensometer is applied to an experiment to study the failure procedure of a granite specimen containing non-penetrating crack (three-dimensional crack). The type and sequence-by-time of cracks on the specimen are determined based on the measurement results from the virtual extensometer. The failure mechanism of the specimen is then analyzed.