Physical mechanism of fragmentation distribution of rock mass under explosion is investigated. It is demonstrated that lognormal distribution is closely related to the multi-fold fracture of the material. In the case of contained explosion, lognormal distribution describes the fragmentation distribution of rock in the vicinity of explosion center where the material is under hydrostatic compression, the strain rate is high, and the fracture is multi-fold. While Rosin-Rammler distribution mainly describes the fragmentation distribution of rock mass beyond the vicinity of explosion center where the fracture is induced mainly by the tangential tensile stress, and the fracture is one-fold.

To demolish concrete cutoff wall successfully in one blasting is a difficulty which arose in the demolition blasting of downstream cofferdams in the second stage of Three Gorges Project (TGP). The problem was caused by grouting steel tubes and supports to immobilize them, both of which were pre-buried in concrete cutoff wall. This kind of structure was never encountered before in demolition blasting of cofferdams’ underwater cutoff wall. If the demolition blasting just exploded concrete into pieces, leaving those steel tubes unbroken and their supports compact, the underwater excavation of explosion residues could not proceed. The key element of the demolition blasting of downstream cofferdams in the second stage was to destroy both the grouting steel tubes and their supports. To solve this problem, this paper used ANSYS/LS-DYNA computational software and in-situ experiments to study the effects of different charge structures and diameters of cartridges on the destruction of steel tubes in explosions. The relationships between the destruction configurations of steel tubes after explosions and charge structures are discussed; and the proper blasting parameters and charge structure are determined based on these discussions. The research achievements are proved by the results of the demolition blasting.

The research for dynamic properties of frozen soil is the development of statics, and it is the important basis of analyzing dynamic instability. The research status for mechanical properties of frozen soil at home and abroad is summarized. Static properties of frozen soil are mostly researched, dynamic properties of frozen soil focus on the low frequency or small amplitude vibration tests. According to the magnitude of strain rate, the dynamic mechanical properties of frozen soil are researched by adopting split Hopkinson pressure bar test under high strain rate. It is an important research for the safe, effective and rapid construction in frozen construction of coal mine and artificially frozen engineering, and it is of great significance both in research and application.

Numerical simulation of single hole blasting in layered rock slope with weak intercalation is carried out; then analyses of stress effect of the rock mass overlying, lamination effect caused by blasting and its affect on the slope stability are conducted. The simulation results that lamination effect has zoning characteristics. Blasting cavity region is formed by explosive gas scouring and lapsing the weak intercalation, the regions out of blasting cavity region are tightness region and segregation region. The weak intercalation out of segregation region is not effected by lamination effect. The rock mass over cavity region is subjected to expansion pressure from explosive gas , the peak pressure of rock mass adjacent to the interlayer wall reaches to 0.75 GPa; the tightness region is subjected to upward pressure derived from squeezing of interlayer, the peak pressure reaches to 0.21 GPa; and the pressure attenuation is relatively slow. The stability of model is decreased by the detachment of rock masses from weak intercalation and tightness region, and segregation region changes the contact state. The lamination effect which decreases the stability of model is testified by shear test.

The rock breaking is different between single particle impacting and real particle impacting drilling. Therefore, it is urgent to study the laws of multi-particle impacting the breaking rock jointly. The space between double particle, the diameter , the initial velocity and the incident angle of particles are selected as design variables. The relationships between these variables and the volume of breaking rock and the invasion depth are established and drawn by means of parametric design language of LS-DYNA and dimensionless method under the condition of double particle impacting breaking rock. The analytical results show that the effect of particles impacting breaking rock will reach to or close to optimum when the space between the double particle is about 0.25 times of the datum diameter, the particle diameters are 0.8–1 times of datum diameter, the initial velocity is 32000–40000 times of datum diameter per second, and the incident angle is 0–40 degree. These results can be used as references for further researches of multi-particle impacting breaking rock.

The umbrella-shaped uplift anchor is an innovative anchor device. Based on the in-situ test, the uplift resistance behavior of the umbrella-shaped uplift anchor has been carried out. Compared with uplift piles at the same site, the capacity of the umbrella-shaped uplift anchors can be obviously improved, while the Q-S curve is under the normal state condition. Because the test conditions are not adequate enough to obtain the ultimate bearing capacity of the umbrella-shaped uplift anchor, the in-situ test of the umbrella-shaped uplift anchor and uplift piles have been numerically simulated with the ABAQUS finite element software, so that the Q-S curve of the umbrella-shaped uplift anchor at the limit state can be obtained. The simulation is divided into two stages. The first stage is adjusting the parameters to make it consistent with the test Q-S curve under the normal state condition. And the second stage is increasing the load to get the Q-S curve of the umbrella-shaped uplift anchor at the limit state. The result shows that the umbrella-shaped uplift anchor can fully mobilize its expanding soil participating in uplift. The Q-S curve further indicates that the uplift resistance behavior of the umbrella-shaped anchor has great potentiality and prominent superiority.

The dynamic characteristics test on granite under impact loading of strain rate between 101 to 102 s?1 is carried out by split Hopkinson pressure bar (SHPB). Three improvements of SHPB are operated: (1) using large-size Hopkinson pressure bar with variable cross-section and strict slenderness ratio to specimen; (2) using impulse shaper which is made of medicinal adhesive and annealed red copper; (3) setting up universal joint between incident bar and specimen. And the dynamic characteristics of granite under repeated impact are obtained by carrying out varying speed loading test. The results show that the granite has strain rate effect, hardening effect and jumping behaviors of stress-strain curve.

Both uniaxial and triaxial mechanical strengths are studied under different weathering degrees of sandstones. The results show that sandstone strength decreases as the weathering degree increases; the effect on the strength of sandstone caused by principal stress difference is linear essentially; internal friction angle of sandstone increases and cohesion decreases as the weathering degree increases; the constitutive relation of 5 segments stress-strain curves of sandstone is established, which is better in reflecting the characteristics of triaxial strength experiment.

Tremendous geological hazards are induced by strong earthquake at the meizoseismal area of the Wenchuan Earthquake, May 12, 2008. The rock mass seismic failures caused by strong ground motions are mainly responsible for that. The problem of rock mass seismic failure under ground motions at meizoseismal area is discussed regard of meaning of meizoseismal area, characteristics of ground motions, definition of rock mass seismic failure, seismic dynamo-relaxed rock mass and methodology. Meizoseismal area is a potential earthquake region of the future earthquake, in which the direct-underground earthquake would happen. The ground motions at meizoseismal area have some characteristics totally different from that outside of the meizoseismal area. It is significant to understand the meaning of rock mass seismic failure at meizoseismal areas considering the nondeterministic characteristics of ground motions. Seismic dynamo-relaxed rock mass is a special type of rock mass seismic failure at meizoseismal areas damaged by ground motions, and it is an important factor causing secondary hazard after earthquakes. The concepts, methods and techniques of related subjects such as rock mass mechanics, engineering geology etc., have laid a good foundation for studying rock mass seismic failure under ground motions at meizoseismal areas whose tasks and aims will be to predict and assess engineering earthquake damage and geological hazards induced by rock mass seismic failure as well as to reduce and to prevent the losses during the future earthquakes.

The nonstationary seismic motion for large-scale underground cavern group located in alpine gorge is artificially simulated, based on the frequency analysis of near-site seismic log and bedrock response spectrum obtained by seismic hazard analysis. The trigonometric series superposition, under the control of two predominant frequencies by the Fourier transform of Panzhihua earthquake records, is used to simulate the seismic motion with consideration of depth modification, baseline modification and high frequency wave. The other earthquake log with similar geological background is also used to get the frequency spectrum if the near-site earthquake log is absent. The finished artificial seismic motions, as the numerical simulations show, fit the numerical analysis softwares such as FLAC and ABAQUS well.

The mechanical model of single microcrack under uniaxial compression loading is established; then maximum circumferential stress theory ( criterion ) is adopted among macroscopic multiple fracture theories to calculate the stability size of single microcrack. According to the fractal damage theory, fractal dimension is calculated in different loading stages; the amount of microcracks is derived based on the definition of fractal dimension; combining the form and size of single microcrack, the relationship between rock porosity and loading value in different loading stages is obtained; according to the formula about p-wave velocity and porosity which has been adopted extensively now, the theoretical formula about p-wave velocity and stress of rock under uniaxial compression loading is obtained. Test on the relationship between ultrasonic and stress of rock is made; then the curve of ultrasonic and stress is drawn. Compared with theoretical curve of ultrasonic and stress, the result shows that this theoretical model is suitable to describe the latter half part relationship between ultrasonic and stress in the whole loading process of rock.

Seepage analysis fractural rock mass has very close relation with other analyses of rock mass. Seepage theory of fractural network rock mass is based on linear cubic law. When the water head is very high or the fracture flux is very large, fracture stream doesn’t abide by linear cubic law; if such seepage is still analyzed by using linear cubic law, it will bring great errors, even make engineering disaster. If the fluid in the fractures doesn’t abide by the linear cubic law, the study for themselves’ rules is very important and essential. The rules of nonlinear seepage and non-cubic seepage are reaearched; it is concluded that (1) if the seepage rule deflected the linear cubic law very much, there would exist great differences in water head and flux; if the seepage rule deflected the linear cubic law very little, the diffrerences would also be very little, it can be simplified to linear cubic seepage; (2) if the seepage rule deflected the cubic-law very much, there would exist great differences in water head and flux; if the seepage rule deflected the cubic-law very little, the diffrerences would also be very little, it can be simplified to cubic seepage; (3) for the nonlinear non-cubic seepage, both the nonlinear effect and the non-cubic effect should be taken into account.

By means of uniaxial closed-loop system and real-time observation system, with the measurement of ultrasonic wave velocity and strain at the same time; the experiments on sandstones fatigue damage are performed under constant amplitude cyclic loading. The acoustic parameters during sandstone fatigue damage including ultrasonic wave velocity, amplitude and waveform are real-time measured and analyzed in detail. Results show that the ultrasonic wave velocity varies temperamentally and reduces following inversed S-shaped line, which can be divided into three phases during fatigue damage of sandstones. The amplitude of ultrasonic wave fluctuates with damage. The waveform alters from regular fusiform to malformation; and its correlation coefficient is descending as a whole with the damage development. The micro destructive mechanism of the sandstones under cyclic loading is analyzed according to the variance of acoustic parameters. The testing results offer a choice of choosing acoustic parameters identifying rock fatigue damage process.

The Poisson’s ratio of soil is a significant parameter which reflects the characteristics of soil lateral deformation. The importance of this mechanical property has not been appreciated as much as it deserves. The variation of Poisson’s ratio is obtained through triaxial test based on local deformation measurement of soil specimen. Because the arrangement and combination structure of material particles are analogous under the same testing method and density, the variation of deformation law of specimen under different cell pressures is similar. The tangent Poisson’s ratio of soil increases when the principal stress ratio increases. It is reasonable to establish the relationship between the Poisson’s ratio and principal stress ratio.

Ultrasonic tests of 21 polymer modified concrete specimens under different loading conditions are completed; and the variations of ultrasonic velocity, weighted spectral area with stress in polymer modified concrete are researched. The research shows that pure acrylic emulsion and styrene-acrylate emulsion can increase the sensitivity of acoustic parameters with stress in concrete; organosilicon mortar naterproof agent and polyvinyl acetate can attenuate the sensitivity of acoustic parameters with stress; and acrylate copolymer emulsion has no effect on the sensitivity of acoustic parameters with stress.

As a special type of the tower-foundation in overhead transmission lines, the rock bolt foundation can give full play to the mechanical properties of rock masses in original state and provide a good pull-out performance. The results of the current prototype test of rock bolt foundation show that in the calculating model of the single anchor foundation’s pull-out capacity which is recommended in The technical requirements in overhead transmission lines foundation design, the hypothetical model of the ideal 45? does not match the actual damage. The calculation based on it makes larger deviations and the results may lead to unsafe design. To this end, based on the limit equilibrium principle and rock intensity, a more reasonable pull-out capacity calculating model, is established, and the relevant formula by mechanical derivation is obtained and simplified. Through the comparison and verification among the calculated values based on derived formula, actual values and designed values, the pull-out capacity is located in range limits and in good consistency with the calculated values of recommended formula . The results are feasible and able to meet the precision of engineering applications better.

Granular flow should be found in many natural phenomena and engineering application. An experimental system was installed with two cylinders to investigate the shear stress in granular flow; both of the two cylinders could rotate respectively; and a series of experiments have been carried out including the shear stress in granular flow with non-homogeneous solids; especially, the parameters, solid concentration, solid diameter and boundary conditions, were measured and analyzed. The experimental results show that the solid concentration and the diameter have important effects on the shear stress of granular flow; the differences between experimental results by Savage (inner cylinder rotation )and Bagnold (outer cylinder rotation ) are due to the boundary slip and rotation eccentricity. On the bases of above experiments, the characteristics of the shear stress have been studied further.

A granular material is a conglomeration of discrete solid, macroscopic particles characterized by a loss of energy whenever the particles interact. Soil is a typical granular material in nature. The concept of effective stress is one of Karl Terzaghi's most important contributions to soil mechanics. It is a measure of the stress on the soil skeleton (the collection of particles in contact with each other), and determines the ability of soil to resist shear stress. However, the soil skeleton is an imaginary concept, and it is hard to measure the geometric and mechanical properties. A few conflicts on its understandings are still remaining. The newly developed granular material mechanics may be helpful to provide insights to soil skeleton. We propose that skeleton is actually the particle connection diagram, and more importantly we found the interparticle forces were transmitted through quasilinear chain structures affiliated to the skeleton. It is necessary to compare the skeleton and force chains. In this work, a series of discrete element simulations were conducted on a uniaxial compression system consisting of 12,400 poly-dispersed particles. We find that skeleton corresponds to the geometric architecture of particle connection, while force chains sensitively response to external loadings though the skeleton is kept constant.

A granular assembly is a conglomeration of discrete solid and exists in nature widely, such as sand foundations, debris flows and landslides, etc. It is found that external loads generally transmit along the quasi-linear path in the granular assembly, and a special mesoscale structure between a single particle and the entire system, called a force chain, is formed. In other words, granular matter has the typical characteristics of multi-scale. A series of discrete element simulations are conducted on a static granular assembly subjected to indentation by a rigid flat punch. By proposing three conditions for defining a force chain, the evolution of the strong force chain network is presented. The distribution of strong force chain length during the indentation of the punch is also analyzed.

A granular material constitutive model considered the particles arranged pattern is developed. A representative unit which consists of several particles is introduced in this model. The relations between stress and strain can be described by the particle concentration, the pattern with particle arranged in unit, and the friction between particles. A Finite element programming work has been done based on the software ABAQUS. A numerical example illustrates that the constitutive model can be applied to numerical analysis of granular material in which the behavior of particles is considered.

Aiming at understanding the segregation phenomena that may occur while the mixture is discharged from storage bin, small scale simulation test is adopted to observe the discharge process and analyze changes of particle composition. The results show that segregation phenomenon of mixture in storage bin at the time of discharge is mainly due to infiltration effect of granular material. During the discharge process, the fine materials infiltrate through the voids in the structure with the effect of the self-gravity, and aggregate segregation occurres. Different aggregate size ratios, distribution widths, average particle sizes and other factors result in different void structures of aggregate, which give birth to different extent of infiltration of fine materials. Thus, the degree of aggregate segregation varied.

It has been realized that, the force chain is crucial to the fundamentals of granular materials. The photoelastic granular material of bi-disperse discs was employed to investigate the evolution of the packing and the force chain when subject to 2D direct shearing. Photoelastic experiments of granular materials were employed for the first time in the study of force chains of granular materials in China. Experimental techniques were dealt with including the development of a photoelastic direct shear apparatus as well as the manufacturing and annealing of Polycarbonate discs. The photoelastic direct shear experiments results as obtained were processed using the digital image processing methods, in which the average color gradient method was introduced to extract the force chain information developed. Anisotropy of the packing of the bi-disperse granular material was observed. The equally important was the localization of intermediate strong force chains based on the statistical analysis.

The rolling-sliding friction is important to the dynamics of granular materials on micro and macro scales. In the granular flow dynamics, the sliding friction has been investigated well, but the mechanism of rolling friction is paid less attention before. The rolling friction is influenced by many factors, and there is no unified theory to describe the rolling friction. The experiment for friction coefficients under the influences of normal loads, roughness of contact surfaces, particle shapes has been carried out; and the transition mechanism of the rolling-sliding friction is studied. It is shown that the particle performs sliding when the particle shape is quite irregular and the contact surface is too smooth; otherwise, the particle performs rolling. Moreover, the sliding friction coefficient and rolling friction coefficient are measured under various particle shapes and surface roughnesses.

Granular matter is a collection of a large number of interactive solid particles. For moist granular systems, such as unsaturated soils, interstitial liquid among particles forms complicated connection structures and displays unique flow behaviours, which affect the strength and deformation of moist granular systems. At present, squeeze flow and shear flow between particles with fluid are hard to analyze in fluid mechanics and granular system mechanics. Based on the Reynolds lubrication theory, squeeze flow between two arbitrary rigid spheres with an interstitial bi-viscosity fluid is studied, and the yield surface paradox is avoided. According to the characteristics of stress distribution, the fluid is divided into both yielding and unyielding regions. Along with the variation of parameters, differences between the thicknesses of the two regions are discussed; and the pressure distribution in these regions is analyzed. Furthermore, the change law of the pressure distribution of the fluid and an integral expression of viscous force are derived.

Granular materials usually display strange mechanical behaviours, and their understandings still stay in the infancy so far. It is reported that a large assemblage of individual solids in granular material further form a clear hierarchy, i.e. microscale for single particles, mesoscale for force chains and macroscale for the whole granular material. Especially, the mesoscale force chain is postulated being a determinative factor in higher scale behaviours. In this review, we introduce 5 widely used detecting techniques of contact forces in particle scales. Due to highly sensitive response of force chain to external conditions, we further classify them into noninvasive and invasive 2 types based on the strength of influence on force chain. We propose that the invasive measurement would be promising for granular material study in the future. At this stage, photoelasticity technique is appropriate for 2D systems. Finally, we briefly introduce photoelasticity experiments conducted in Tsinghua University.

Using a developed low frequency inverted torsion pendulum, the relative energy dissipation in sheared granular materials is investigated. The amplitude and the frequency spectra of fine sand and glass beads are measured. The results show that with the increase of amplitude, one peak of energy dissipation is found in amplitude spectra; while with increasing frequency, four peaks of energy dissipation are observed in the curves of frequency spectra, corresponding to four decreases of the relative modulus. And there exists a peak (corresponding to a critical depth) in the curves of relative energy dissipation along with the inserted depth of probe with different oscillating amplitudes. Based on the mesoscopical analysis of granular materials, a rheological model is presented to explain the rheological dissipation mechanics; and the results indicate that the friction among particles not only dissipates the energy but also enhances the elasticity of the system. The frequency spectra of fine sand reveal a different dissipation: the resonant dissipation.

With the methods of wavelet analysis and fast Fourier transform, actual original signals from engineering project in near, medium and far zones of blasting vibration are separately decomposed and reconstructed; and time signals and spectra of all sub-frequencybands are obtained. On this basis, distribution characteristics of spectra and energy of blasting seismic waves along all zones are studied with Matlab; and it is pointed out, that the values of dominant frequency in blasting vibration zones is in attenuation sequence: near zone, medium zone, far zone; as the scaled distance increases, low frequency bands share higher proportion of total signal energy, while high frequency bands share lower; signals in lower frequency bands have longer duration; in addition to the frequency band that the dominant frequency locates in, when the band is from 0 to 2.441 5 Hz (close to the natural frequency of the buildings), blasting vibration signals in the horizontal direction occupy an assignable proportion of the energy; and thus the aseismic construction in horizontal direction is especially important for building structure designs.

Currently, the shortage exists in the design of bolting for coalmine roadways yet, which results in the poor performance of rock bolt, waste of bolting material and high cost. Basing on the interaction principle of surrounding rock and rock bolt, the superiority of bolting can be performed wholly if the parameter design of bolting is determined by in-situ measurement. In the paper, the optimal parameters of bolting are determined with the method by which the bolting parameters are calculated theoretically and revised based on the measurement value of bolt force, according to the roadway condition of a coalmine in Shaanxi province. The application shows that the optimal bolting parameters can be obtained quickly by the suggestion in the paper. In this case, the bolts will perform wholly support capacity and the optimization of bolting realized. The finding is significant in practice and valuable in mining engineering.

Rainfall in the western part of Inner Mongolia Autonomous Region is very rare. In this area, the limited rainfalls usually concentrate in a short period, which sometimes cause the instability of highway slope. The instability mechanism of highway slope caused by rainfalls in arid area is discussed；and the analysis method for slope stability evaluation is suggested. A practical case study is carried out by using the proposed theory and FE method. The method proposed can be for reference in researching and designing highway slopes in similar area.

Based on model tests and mechanical calculation, destruction mechanisms and forms of tunnel are analyzed. Taking safety factors calculated by strength reduction finite element method as the stability criterion is put forward. The stability marks of all kinds of rock masses are put forward in all kinds of surrounding rock classifications. Based on the above, the stability marks of all kinds of rock masses, especially one kind of new quantitative symbol, which is using safety factors of rock masses in non-lined situation as quantitative symbol is proposed. Based on the given corresponding safety factors, the strength parameters of rock masses for improving the accuracy of the strength parameters are deduced. The computational methods of designing rock tunnel, calculating safety factor of rock masses and lining work by strength reduction FEM and FEM respectively are proposed. In addition, the numerical calculation to one Qingdao underground work is carried on, and the safety factors of rock masses and lining work are calculated respectively. The initial standards of designing rock tunnel is that after initial lining, the safety factor of the rock masses is not less than 1.15 to 1.2, and the safety factor of initial lining is not less than 1.3; the safety factor of the rock masses is greater than 1.25 and the safty factor of lining is greater than 2.0 to 2.4 after the second lining, which ensure the tunnel security during construction and operation

During constructing the first class interprovincial road from the north Xinlin to Zhalantun in Inner Mongolia Autonomous Region, serious slope slide and collapse occurred at several places along the road. The current professional codes for road design and construction have not involved the road design and construction methods in frozen area at high latitude. Furthermore, little information can be found for reference. Based on the data collected from large scale investigation, the failure mechanism of the slope in this area is analyzed. Combined with the demonstrating project, the reliable construction procedure is suggested; and the corresponding calculation methods are presented. The research achievement can be for reference in designing and constructing roads in similar circumstance.

The large-scale landslide in Wulong county government is 280?340 m long and 15?35 m thick. Landslide thrust is up to 9 000 kN/m; a row of piles cannot resist such a huge landslide thrust. So multi-row embedded anti-slide piles is used in this landslide treatment. The length of piles is reduced by about 1/3. Project investments are saved. The design and the calculation method of the multi-row embedded anti-slide piles in landslide treatment, which focus on the calculation and analysis of landslide thrust as well as the length of embedded anti-slide pile based on the strength reduction FEM, are described.

The floor water inrush in coal mine is a complicated multi-physics coupling issue. Combined with fractured zone under the conditions of stope mining background, the coupled hydro-mechanical module of Universal Distinct Element Code (UDEC) is used. And the dynamic development and distribution of fault deformation and stress, floor abutment pressure, flow vector and flow velocity are systematically analyzed as the working face advances. It is shown that the coal mining process of stope sill and faults fractured zone are mutual influenced. The abutment pressure which is representative of mining-induced stress is the main inducement of forming water flowing fracture zone and making activation of fault. While the presence of fault makes the stress more concentrated between working face and faults fractured zone, which increases the risk of floor water inrush. In addition, the water flowing fracture zone mainly concentrated in front of and rear of the working face, which is the main channel of floor water inrush.

Traditional supporting design of rock foundation pit often ignores the interaction between rock foundation pit and supporting structure as well as the effects of adjacent buildings on the supporting structure and the stability of foundation pit. Combining with practical engineering, adopting finite element program of PLAXIS, the stability and the deformation of rock foundation pit, rock lateral pressure, the influence of excavation on the adjacent buildings and the optimization design of supporting structure are analyzed respectively through finite element strength reduction method and finite element method. According to the structural design regulations of high building and design standards of foundations, the deformation control conditions of adjacent buildings are put forward, which are taken as the controlling basis, the calculation of rock lateral pressure and the design of supporting structure of rock foundation pit are carried out according to the limit values of deformation. This method can save the construction cost and cut down the construction period effectively.

For electing tailrace tunnel area in Qingjiang Shuibuya underground power plant, a 3-D numerical model is established; multiexcavation and multireinforcement construction scheme are designed by orthogonal design; excavation and support are simulated; displacement and plastic zone in surrounding rocks of large cavern group under complicated geological conditions are studied. Evolutionary neural network is used to predict the other schemes and optimize global schemes; integral stability criterion is constructed ; and the global stability of large cavern group is analyzed. As a result, the most optimal scheme is obtained, which provides references for design and construction.

Taking Indian Koyna earthquake as input dynamic loads, a dynamic numerical analysis model of soil slopes is established by ABAQUS program. Based on this, the dynamic response under earthquake is analyzed. It is shown that the slope has an amplification effect on earthquake acceleration. The horizontal peak acceleration in the slope roof is 1.0 m/s2; approximately 3 times of the inputted earthquake peak acceleration; the vertical peak acceleration in the slope roof is 0.8 m/s2; approximately 3.2 times of the inputted earthquake peak acceleration. When the soil body is damaged, the slope body displacement will be enlarged along with the increase of the earthquake duration time, which causes a distortion cumulative effect. The results are helpful to further researches on the slope instability mechanism under earthquake.

It is necessary to develop empirical evaluation methods for highway construction in mountainous areas in China due to the complexity of geotechnical engineering and the lack of completeness and certainty of geotechnical engineering data. A new slope stability rating system based on Bieniawski’s RMR, Barton’s Q, Romana’s SMR and Palmström’s RMi is put forward. The system employs a new method for describing and rating discontinuity condition considering the influence of raining. The condition of controlling discontinuity is considered in the system; and the rating standard for it is established. An example shows that the system is easy to use and objective to some extent.

Based on the high slope engineering of Guangzhou Skeet & Trapshooting Training Centre, some of the key technique problems of the high slope designing are discussed; and the reinforced design of the high slope is introduced. It is assumed on the same physical model and boundary conditions , the different limit equilibrium methods(LEM) are adopted to analyze the stability of the high slope; and the different results involves different methods are analyzed and the reasons are discussed. Lastly, the finite element method (FEM) based on shear strength reduction technique are adopted; and the unreinforced slope and the reinforced slope are concerned and calculated. It is pointed out that the deformation characteristics and failure mechanism calculated by FEM are different from that’s from LEM because of its principles and assumption.

The reliability of the conclusion by numerical methods depends on the selection of mechanical parameters of rock mass. Based on the damage evolution analysis of rock, the relationship between the damage variable and the mechanical parameters is studied. It brings forward a method of estimating rock material parameters (elastic modulus, Poisson’s ratio, cohesion and friction angle) by damage variable. Firstly, it analyzes rock damage evolution process of highway tunnel in excavation by bifurcation orientation. Secondly, it defines the initial damage variable by elastic p-wave velocity, and sets up ANSYS numerical model of the progressive destruction tunnel according to the site monitoring data of Bicheng tunnel. An example is given to estimate and analyze the macroscopical mechanical parameters of various surrounding rocks. The analytical results reveal that this method can effectively determine the magnitude and estimate the macroscopical mechanical parameters.

The macro-mechanics phenomena of piles on uplift loading are closely related to the changes of its meso-mechanics. Piles on uplift loading are analysed with PFC2D (Particle Flow Code in 2 Dimensions) numerical simulation of meso-mechanics. PFC2D is used to simulate numerically the character of meso-mechanics on soil, to study the uplifting displacements of pile, the distribution and velocity of sand particle, the surface of rupture in soil and to compare with the results of material object tests. Not only did PFC preferably reproduce the relationship of uplift loading and displacement of pile experiment but also suitably simulate pile、s gradually progressive failure pattern. The changes in the meso-syructure and the forming process on the shear zone of soil body have been analyzed. The cause of forming uplift pile shear zone is strain softening effect of the dense sand. Particle contact force of PFC2D numerical simulation and pile side frictional resistance of physical tests are identical. The load-displacement curves are consistent with the results of numerical simulation and physical tests. It is closely related to pile side frictional resistance, the forming process of shear zone, the load-displacement and particles distribution, particles speed, particle contact force of PFC2D numerical simulation. Changes of soil particle meso-structure and displacement of piles of PFC2D numerical simulation are initial study of meso-mechanics character and macro-mechanics response.

In view of the complexity in the choice of blasting scheme, based on gray correlative analysis, by means of analytical hierarchy process, judgement matrix is adopted to determine weight of each evaluating index; a comprehensive evaluation model which combines correlation coefficient with the weight of evaluating index is presented. The model embodies the influence extent of each evaluating index to the whole by weight form; it uses judgement matrix method to determine weight in order to avoid subjective factor and analyze blasting scheme by correlation degree. Evaluation of blasting scheme of Huipodi mine indicates that the comprehensive evaluation model makes results more scientific and rational.

In China, composite foundation has been widely used in civil engineering. What is the seismic response of this type of site? This is an important issue as to the input earthquake motion for structure design. By using the two-dimensional finite element program–FLUSH, the ground surface peak acceleration and acceleration response spectra of different replacement ratios under different ground motion inputs are calculated. The influences of replacement ratio on seismic response are studied; and some valuable results are obtained.

The constitutive relation of hypoplastic model for granular materials is represented by Jaumann stress rate and deformation rate, the tangential stiffness matrix for finite element simulation of hypoplasticity is given based on Gudehus-Bauer model with Jaumann rate of Cauchy stress and deformation rate, and it is illustrated that the numerical implementations of hypoplastic model based on ABAQUS must resort to UEL interface proper. For simplifying the of programming development, two methods for tangential modulus matrix are suggested combing with finite element method, viz. tangential modulus matrix based on general invert of matrix and approximate tangential modulus matrix, so numerical methods for implementations of hypoplastic model by UMAT interface are formed. By the approach suggested; the complexity of programming is reduced; and the post processing of ABAQUS can be utilized, so the work efficiency is improved. Numerical examples show the validity of methods suggested and fensibility of programming code.

The tunnel displacement measurement is only a part of the whole displacement curves limited to construction site conditions at present, however, there are little research on the unmeasured part of tunnel rock mass displacement. The measured data of arch crown settlements of the subsea tunnel each part rock mass was analyzed by regression method; so we get the first part of unmeasured displacements in CRD1 part and CRD3 part(Y1) .The whole curves of the subsea tunnel each part rock mass was studied by the finite difference method; and we gain the proportion of the unmeasured displacements in the whole displacements, so we can give the second part of unmeasured displacements in CRD1 part and CRD3 part(Y0), then we know the whole curves is the sum of the measured part(Ym) and the unmeasured part(Y0 and Y1

Granular materials exhibit irregular shapes under natural conditions, and the particle shape has great effects on its macro mechanical behaviors. Direct shear tests are simulated by using discrete element model (DEM) with clumps of spheres resembling the real shapes of granular materials, and the effects of different particle shapes on the shear strength are discussed. A clump is constructed by clumping spheres with different numbers, diameters, orientations and overlaps. The quaternion method is introduced to transform the rotation, the resultant force and the moment acting on a clump in global and local coordinates. The interactions between particles are described by Hertz-Mindlin contact model incorporated with the nonlinear normal viscous force and Mohr-Coulomb friction law. Seven different clumps with the same mass probability distribution are generated and used to simulate direct shear tests under different normal stresses. For each clump, the shear strength is analyzed. With the simulated results, it is shown that the interlocking among particles can be simulated well with the clumps of spheres. The presented model provides a foundation for analyzing the macro behaviors of irregularly shaped granular materials.

Casing deformation and damage have been found in halite beds in many gas wells of a gas field after 5.12 Wenchuan Earthquakes. It is very important to find out the reasons and laws of the casing deformation in order to control and repair them. Distribution laws of the casing stress and deformation are found out by applying true three-dimensional contact finite element analysis before the earthquake. Based on the above, applying extra different earthquake loads to top face of the model, the casing stress and deformation are studied again. Careful contrast of the two results shows that the level of casing stress and deformation is higher in halite bed than that in other beds whether before or after earthquakes; and the basic laws are that the higher earthquake power is, the higher level of casing stress and deformation is in halite bed. Finite element calculation results also reveal that 5.12 Wenchuan Earthquakes are the direct reasons for casing deformation and damage because the Mises stress of the casing in halite bed is already over the yield limit of its material only under the influence of vertical component load of 5.12 Wenchuan Earthquakes.

The drilling process simulation of bits is important to optimize bit design, to improve efficiency of breaking rock, as well as to bit selection. Based on oil field drilling data, black-box method is used to be a basic modeling method of interaction model between bits and rock. Two important simulation models are built, which determine bit drilling performance, pit model of tooth and force-penetration model of tooth penetrate rock. Parameters of model are estimated by error gradient descent algorithm which includes parameters of bit structure and the rock properties. Then the simulation of bit drilling process is made. The main ideal of modeling by the drilling data is beneficial to use these data to improve the model, and reflects the various drilling conditions better. It also improves the practicability and economical efficiency of simulation technology of bits breaking rock.

The three dimension particle flow code calculation program is used to simulate the large scale triaxial drained shear test of rockfill materials. During the formation of numerical specimen a procedure is writing to generate particles of assemly until the target porosity and gradation composition are achieved. Dynamic relaxation method is applied to solve DEM (discrete element method) equation. Local damping is used to accelerate to arrive at a steady solution in a reasonable number of cycles to dissipate energy of the particle system. Normal and shear contact bond strengths are used to increase the assemly’speak strength.With the selected micro parameters the numerical simulation tests of the large scale triaxial test are performed under series of confining pressures. The stress-strain curves from numerical simulation with the selected micro parameters are in agreement well with the results of the laboratory test. So the particle flow code program is a better method to simulate the large scale triaxial drained shear test of rockfill materials. A large range of shear dilatancy occurs with the increase of axial strain because particle shape and breakage are not considered.

Structure failure subjected to seismic load induced by blasting is a complex process characterised by damage monotonic accumulation. So, attention should be paid to structure deterioration course besides the influence of geometric distance, blasting condition and geological condition on vibration intensity during blasting seismic effect research. It is suggested that fatigue theory should be used to analyze blasting seismic effect. Firstly, the method measuring stress spectrum induced by blasting is introduced. Secondly, an improved scheme is proposed to overcome the defects of rain flow counting model. The improved model simplified the process of counting by integrating equivalent points compression, peak-valley points detection into cycle counting. Then, the distribution of frequency is obtained by using the improved model to analyze the stress spectrum of vibration. The statistical result indicates that most fatigue cycles are low amplitude cycles, and the proportion of tensile and compressive cycles is very high.

There is only one shear band formed at last when the soil specimen bears shear load, although several fine shear bands appear at first. For analyzing this phenomenon, the development of shear bands in saturated rock is thought to be a multi-stage process and is numerically investigated. The evolution of shear bands from several finite amplitude disturbances (FADs) in pore pressure is studied. The numerical analysis reveals the detailed processes that the FADs evolve into a fully developed shear band. It is shown that the shear banding process consists of two stages: heterogeneous shearing process and true shear banding process.

The finite element commercial code LS-DANA is used to study the tunnel anchored with single anchorage structure or new type composite anchorage structure under explosive loading. The course come into being on shock wave and explosive pit and the pressure wave in wall rock about explosion and the crack in constructional part of composite anchorage structure under explosive loading is analyzed. The dependability of the experimental results is validated; and some elementary cognition is acquired on the mechanism. The results show that: the size of the explosive pit about the two models is tallied to the experimental results; the constructional part of composite anchorage structure mades the medium come forth part free surface outside anchored area, when explosive shock wave by free surface bring reflect elongate wave then produce the crack; the peak value of plumb vibrational acceleration on composite anchorage structure tunnel vault is 23.7 % less than single anchorage structure tunnel; single anchorage structure tunnel is easier come forth structure-breaking and elongate desquamate wreck than composite anchorage structure.

For the purpose of intellectualization and automation in the process of 3D modeling and also for simplification of complex geological body modeling, DXF interface program which can read the borehole data and some other drawing data from CAD and rewrite it to database or visualize it is programmed. The 3D fast modeling method is put up with, which dose the interpolation with stratus attribute values by means of GA-Kriging. Moreover, the functions including modeling, contours drawing, display of boreholes, slicing of strata, extraction of special stratum, calculation of volume and so on. In the programming of Kriging interpolation method code, the GA intelligent algorithm is applied for the calculation of constant parameters such as nugget constant and range. It is proved that in this way global optimal solution of the parameters can be obtained easily. Finally, an engineering instance is given to test whether this kind of modeling method and related program codes are appropriate or not; it is shown that in this way the 3D modeling becomes easy and efficient.

In order to model 3D strata using comprehensive data of ground penetrating radar (GPR) graph and borehole, virtual borehole data for modeling are extracting from GPR data by comparing with borehole sampling data according to in-phase of reflection wave group and reflection wave shape analogy; the grid interpolation method based on distribution characteristics of this kind data is given according to surface fairing condition. By using this method, strata of one area is modeling.

When simulating the penetration of projectile into concrete targets, it is an important and complicated job to find a suitable material model of concrete and its parameters. A kinetic material model of concrete has many parameters which often add up to dozens; most of them cannot be obtained directly by experiments; even some of them are physically meaningless. In common cases, a few parameters can be experimentally measured in advance, and the rest parameters will be obtained by deduction according to computational results. In view of this condition, LS-DYNA provides users with a function which is able to generate parameters of concrete automatically. The function is developed by Schwer et al by means of a great deal of summaries on damage concrete model. It facilitates users to perform numerical simulations about the penetration of concrete to a large extent. In order to check the effectiveness of this function, the numerical simulation of Forrestal’s experiments is conducted, and the comparative analysis is performed for the results from computation , experiments and empirical formulations. The results show that the function is a simple and effective approach to study the penetration problems of projectile into concrete targets.

The new composite anchorage structure indicates the ‘bolt-tectonic measure’ composite anchorage structure, it is applied to cavity reinforcement and support. ‘Tectonic measure’ indicates to construct a section of empty hole located at the end of inner bolt with processing the hole surface. This section of empty hole can weaken the medium, and it is named as ‘weakening hole’. The optimum design factors of the new composite anchorage structure include: ① weakening hole diameter, d; ② weakening density; ③ weakening length, l; ④ anchorage zone thickness, t. The optimum design of the above four factors is analyzed through numerical simulation with LS-DYNA code. The conclusions show that: optimum weakening hole diameter, 1.0; optimum design of weakening hole density is 24 weakening holes along cavity circle; optimum weakening hole length, 25 cm; optimum anchorage zone thickness, 25 cm (or the ratio of anchorage zone thickness to weakening hole length is 1).

The general dynamic canonical descent(DCD) algorithm is able to avoid being trapped by local optimization with a limited speed, and does not assume the cost function to be differentiable if firstly given a appropriate space interval. The iterative format of the algorithm is discussed. The mutative DCD algorithm is based on the general DCD algorithm; the two algorithms are compared in numerical experiments and engineering application. The recults show that the mutative DCD algorithm can converge to the global best point with a few objective function evaluations; and a tradeoff between time and space complexities and the capabilities to locate the global optimum up to a certain precision with a good numerical stability and credible results are obtained.

In geotechnical tests, particle diameter (R) or sample size (L) accounts for the mechanical properties of coarse-grained soils. Correctness and precision of the results modeled with the discrete element analysis (DEA) is limited by the calculation scale, which is also determined by the characteristic length ratio L/R. Scaling law that describes relationship between micro-parameters and macro-parameters of coarse-grained soils is obtained using dimensional analysis; and it is shown that the shear resistance of coarse-grained soils depends on the characteristic length ratio L/R. A series of numerical triaxial tests are performed; it is shown that the L/R has little effects on the shear resistance when L/R is larger than 40; when L/R is less than 30, the shear resistance will be noticeably affected by L/R because of the effects of the boundary friction. The servo-mechanism provided by PFC2D/3D（Particle Flow Code, ITASCA®）is also discussed.

By taking the papers of Chinese Journal of Rock Mechanics and Engineering in 25 years as the research subject, this article is trying to study the disciplinary structure and its evolution of Rock Mechanics in China based on the concept of History of Scince and Technology and the Chinese Laborary Classification. In order to explore the developing process of Rock Mechanics in China, this article will also help to trace the track of development for the discipline from one side.

Deformation monitoring is an important basis and technical measurement to ensure the project construction and operation, it perfects the geotechnical engineering design method and plays an important role in project construction and operation stage. Traditional manual monitoring method is difficult to ensure the monitoring frequency and result because of its time-consuming and hard sledding. Based on the public telephone network and the GPRS network, one kind of digital monitoring wireless transmission method and equipment has been designed for automatic monitoring and it is especially suitable for difficult condition automatic remote measuring. to establish and control The data acquisition instrument through public telephone network data acquisition communication facility is established and controlled by using master control computer and necessary control software, the monitoring result to the master control computer through the GPRS network wireless transmission is returned. From this method, the remote measuring for distortion numerical monitoring in geotechnical engineering has been accomplished. The apparatus is mor accurate and stable than the traditional method for its simple structure, high precision, automaticity , stability and low error rate. The deformation monitoring in geotechnical engineering is no longer difficult and arduous.

The number and type of sensor is becoming more and more on modern vibration tests. According to the actual test, 64-channel high-speed synchronization acquisition system has been developed, which can match charge-output sensor and voltage-output sensor. This system has two application modes, the real-time data acquisition and the transient acquisition. It has several advanced functions, such as program controlled amplifier, program controlled filter and auto zero. The whole system adopts master-slave structural design method, which has the following advantages, such as simple structure, low cost and high reliability etc.