It is inconvenient for research the deformation mechanism of materials for earth-rock dam under dynamic loading using equivalent linear viscoelastic model, though it has been applied widely, because the stress-strain expressions haven’t been derived in this model and the energy dissipation don’t be described. In this paper, the Ramberg-Osgood constitutive model with variable parameters has been researched; and its adaptability has been discussed. It is found that the Ramberg-Osgood constitutive model is not applicable for describing the dynamic property of soil in small strain level. Also the expression of variable parameters is derived; the hysteretic loops have been drawn in different dynamic shear levels. A solid foundation has been established for studying the dynamic dissipation and strain mechanism of earth-rock dam materials.

The hollow cylinder apparatus at Tongji University was used to conduct the torsional shear test on the dry TJ-1 lunar soil simulant by applying fixed and rotated principal stress axes. In the perspective of the stress-strain response, the investigation is focused on the effect of the principal stress direction and the deviatoric stress ratio on the anisotropy of the dry TJ-1 lunar soil simulant. In addition, their impact on the non-coaxiality of the specimen is also further explored. The test results indicate that the principal stress direction and the deviatoric stress ratio significantly affect the anisotropic behavior of the TJ-1 lunar soil simulant. The non-coaxiality observed in the torsional test with rotated principal stress direction is more remarkable than that in the tosional test with fixed principal stress direction. In the test with rotated principal stress direction, the non-coaxial angle decreases and then increases at a small deviatoric stress ratio; while the angle continuously decreases at a high eviatoric stress ratio and diminishes as the specimen failure. This study will help to fill the gap in the research with emphasis on anisotropic behaviors of dry sands; and it also provides necessary theory beneficial to the future development of human infrastructure on the Moon.

The results of the samples with three different types of infilled joint soils (mud with fragment, mud with sand and muddy) and the ones with three different water contents (10% ,7% and 3%)around the in-situ water content by the reversal direct shear tests (normal stress is between 2 MPa and 10 MPa) and particle size distribution (PSD) tests (around the shear zones) were compared to get the effects of the different initial particle size distributions and water contents on the infilled joint soil. Some conclusions are drawn as follows. ①The degree of particle crushing is higher quantified by Br index (relative particle crushing potential) for the coarser particles (d60 is greater). ② Dry particles (lower water content) tend to crush to tiny particles due to abrasion and wet particles (higher water content) generate more relative large particles due to fracture or attribution. ③ Coarse particles have limited effect on the peak strength; besides nonlinearity of residual strength envelope is higher for coarser particles(d60 is greater). ④ Cohesion and friction angle decrease linearly with water content; moreover the samples with lower contents have a higher nonlinear residual strength envelope. ⑤ The residual friction angle decreases linearly with clay fraction; in addition, the equation proposed could be used to estimate the residual friction angle of the infilled joint soils preliminarily in practice.

Slope stability problems related with the swelling diatomite are met during the construction of Baoshan-Tengchong highway in Yunnan province. After field investigation of the typical geological sections and laboratory tests of composition, microstructure and mechanical properties on the samples from Wuhe town, Mangbang town, Tuantian town of Tengchong county, Yunnan province, it is revealed that the Neogene diatomite in the Mangbang formation is a type of clayey diatomite with rich swelling clay minerals, and belongs to very soft swelling rock. Natural clayey diatomite samples have strong structural properties, which lead to the relationship between their physical properties and mechanical properties against the traditional rock/soil mechanics laws. For example, the samples have void ratio up to 2.20-2.78, liquid index 0.66-2.73, while their uniaxial compressive strength can be up to 1.09-2.11 MPa. Comprehensive researches indicate that the occurred geo-hazards including landslides and weather-flaking of clayey diatomite slope along the Baoshan-Tengchong highway are closely related to their engineering properties.

The uniaxial compression experiments on the sandstone samples containing three pre-existing fissures (the sample scale of 80 mm×160 mm×30 mm, and fissures angles of ? = 30°, ? 1 =60°) and carried out by using rock mechanics servo-controlled testing system, to investigate the effect of ligament angle ? 2 on strength failure and crack coalescence behavior. Compared with intact sandstone sample, the stress-strain curves of sandstone sample containing three fissures show more stress drops, and their peak strengths also take on a reducing tendency, but the reducing extent is closely related to ligament angle ? 2. When ? 2 increases from 75° to 90°, the peak strength reduces to 77.82 MPa from 82.04 MPa; whereas when ? 2 increases from 90° to 120°, the peak strength does not have a distinct variance. The failure mode of intact sandstone sample is a typical axial splitting fracture; but the sandstone sample containing three fissures results from a lot of crack initiation and coalescence at the tips of pre-existing fissures, so as to lead to the ultimate unstable failure. By using photographic measuring technique, the effect of ? 2 on the crack coalescence behavior of sandstone sample containing three fissures is discussed. The results show that the coalescence in the specimen containing three fissures (? 2 =75°, 90° and 105°) occurs between fissure ① and ③, fissure ② and ③, but no coalescence is observed between fissure ① and ②; but in the specimen containing three fissures (? 2 =120°), the coalescence occurs between fissure ① and ③, fissure ① and ②, but no coalescence is observed between fissure ② and ③. Finally, the relationship between microscopic deformation behavior of sandstone samples containing three fissures and crack coalescence process is constructed.

Many scholars have performed a large amount of researches on soil strength with considerable achievements. But the influence of soil structure on its strength has always been the difficult point. A soil structure strength model is established based on soil particle connection. From the analysis of this soil structure model established, it is found that the strength of soil mass is directly associated with the connection strength among particles and the distribution pattern of connections. When the stress-strength curve family in statistical domains is used to macroscopically analyze the soil mass properties, the yield surface composed of several curved surfaces can be gained. The analysis of examples of simplified soil structure morphology indicates that an isotropic stress-strength model can be obtained when the connection in each direction is evenly distributed. In addition, when the spatial characteristics of statistical domains are considered, for different local coordinates of macroscopic stress in the statistical domain, the stress gradient may influence the soil strength. This is exactly what the classical theories can not explain. Therefore, the strength model of soil structure being established is a kind of new and effective analysis method for structural soil.

A series of isotropic consolidated drained true triaxial tests with different Lode angles in the same π plane are carried out with an automatic controlled mixed boundary true triaxial apparatus. The maximum and minor principal stresses are applied by two pairs of rigid platens; and the intermediate principal stress is applied by water pressure in triaxial cell. Undisturbed soil sample is prepared by block sampling method; and totally 5 drained tests with different Lode angles (0°, 15°, 30°, 45°, 60°) are presented. Test results show that the shear strength, the yielding & failure points of Shanghai soft clay decrease while Lode angles increase. The volume change increases first and turns to decrease when Lode angle is larger than 30°. In general, three-dimensional strength of the Shanghai soft clay obeys the SMP (spatial mobilized plane) failure criterion.

The piles of jacket platform move in cycles, so as to increase excess pore pressure of soil, decrease the lateral soil resistance and weaken pile foundation. The basic natural frequency that based on equivalent simplified pile theory not considering the degradation of pile foundation which fixing the pile at 6 pile diameters below mudline still has some difference with the test result. In a simulation experiments, cyclic environmental loading impose in jacket platform, a 1:10 scale model, and measure the vibration characteristics in x and y directions of jacket platform model after different cyclic loadings. The experiments aim to study the relation between pile foundation weakening and platform horizontal vibration characteristics. According to experiment results, lateral soil resistance show different degrees of decay in different cycle loadings; and the degradation of pile foundation is related to the amplitude and frequency of reciprocating motion of piles. Because of the effect of pile foundation weakening, the basic natural frequency of jacket platform decreases when lateral soil resistance decay. The test values of fundamental natural frequency are lower than the calculated values by 15.5% in x direction and 6% in y direction. And the differences increase to 22% and 13.14% after the degradation of pile foundation occurred. Assuming system damping is proportional damping, the degradation of pile foundation has a small impact on system damping.

Hydrate saturation and effective confining pressure can significantly influence the mechanical behaviour of hydrate-bearing sediments. In the case, that the effects of the hydrate type, grain size, and testing conditions are excluded, these two variables are the critical factors that determine their elastic modulus. Based on the relationship between equivalent elastic modulus and hydrate saturation, a power function is established for the damage variable, which takes into account the influence of effective confining pressure. Drucker-Prager failure criterion is adopted to describe the strength of a micro-element of hydrate-bearing sediments. By assuming that the variation of the micro-element strength follows Weibull’s distribution, a statistical damage constitutive model of hydrate-bearing sediments is developed. By comparing the simulated results with the experimental data available in the literature, we show that the proposed model can describe the stress-strain behavior of the hydrate-bearing sediments very well under the triaxial shearing condition. The results can provide reference for numerical simulation of engineering properties of gas hydrate sediments.

Slaking is one of the most basic characteristics of swelling rocks. However, criteria refer to slaking and characteristics of collapsed scraps are rare among rapid identification and classification criteria available. Thus, it is necessary to explore into slaking and grain size distribution (GSD) of the dry collapsed scraps of swelling rock and their relationships with the level of expansibility, which can complete the rapid identification and classification criteria with respect to slaking. With argillaceous rock samples collected from Daban Tunnel in Xinjiang Uygur Autonomous Region, and Heidong Cavern of Taizhou and Shepan Island in Zhejiang province, laboratory tests of saturated water absorptivity of dry rock block and slaking test are conducted; and GSD of the dry collapsed scraps, slake durability index and their relationship with expansibility derived from saturated water absorptivity of the swelling rock are analyzed. Results show that the effective grain size, grain sizes of the particle group with the maximum content and slake durability index are inversely correlated with the level of expansibility of the swelling rock. It is concluded that GSD of dry collapsed scraps of swelling rock can approximately act as an indicator for the level of expansibility.

For EPB (earth pressure balance) shield tunneling, one must properly choose driving parameters to maintain face stability and reducing soil displacement and ground subsidence. In this paper, to research the relationship among shield machine parameters and its impact on the ground displacement by in-site monitoring of Hangzhou metro line shield tunnel construction. The work for in-situ monitoring a shield tunnel construction includes: measuring ground settlement, lateral displacement, excess pore pressure and recording the working parameters of the shield machine. The results show that: the fluctuation for the total thrust force, the earth pressure on chamber and the torque of cutter disc are basically synchronous; ground settlement are mainly influenced by soil removal efficiency before the shield machine arrivals; construction settlement are in inverse proportion to the pressure difference between the inside and outside of the soil chamber; the excess pore pressure begins to decrease rapidly after the shield tail passes through for 0.5 to 1 days; and it completely disappears after 10 days. Settlement after construction is divided into the accelerated subsidence stage and the slow subsidence stage. It accounts for more than 50% of the total ground settlement; and it continues to develop slowly after the dissipation of the excess pore pressure.

This paper deals with the influence of capillary water on the strength and deformation of soils, and on the seepage flow state of levees and dams. Silty soils possess both higher water head and higher permeability, water pressure transmitting rapidly. So that the influence of capillary water in the engineering with silty soils is obvious. The principal research results are: ①According to the comparison tests of unconfined compression strength with samples immersed in the water or not, and with theoretical analysis, it has been demonstrated the capillary water head results the further consolidation and strength increasing of the soil. The strength increasing values of the tests are the same as the values of theoretical calculation. ②Analyzing and calculating the decreasing process of capillary water tension accompanied by soil expansion in silty surface strata on heavy rain condition. ③Using electric analog test and sand model test, the influence of capillary water on the seepage flow state of levees and dams is studied. The capillary water results the increasing of the seepage flow quantity and the height of release point. ④Two new empirical formulae of capillary water head and permeability coefficient of sand and silty soils are presented. The research results can be applied to the engineering of foundation foundation pits, levees and dams with silty soils.

Taking the expansive soil in Guangxi as the research object, considering the influence of vegetation, field seepage test and mechanical test of vegetation root system are carried out. Based on the results of test, numerical simulation work on vegetation protection mechanism of cut slope is put forward. The results show that there are two different aspects to maintain the stability of the expansive soil slope, which are vegetation root reinforcement effect and vegetation evaporation and transpiration; and there is a successive process in rainfall to perform the protection behavior for vegetation root reinforcement effect and vegetation evaporation and transpiration. The reinforcement effect of the vegetation root enhances the strength of the soil. Vegetation evaporation and transpiration prevents the soil strength decay. Meanwhile, it is found that the soil with the vegetation covered should adopt different permeability curves in the wetting and dehumidifying process. The vegetation protection is very weak after construction because the roots will grow for a long time. So, study of the vegetation root mechanical characteristics in growth period is of great significance. Research result of this project has important reference for the development and application of design and construction for vegetation protection of expansive soil cut slope.

Based on indoor model tests, the research on factors influencing bearing capacity of rock-socketed piles in karst area is carried out. The tests indicate that, with the increases of roof thickness and cave migration position, the ultimate bearing capacity increases gradually; with the increases of cave diameter, equatorial and polar radius, the ultimate bearing capacity decreases gradually. The failure zones are less than 3d range at vertical direction and less than 4d range at horizontal direction. Combined with the model test results, the analysis of influencing factor sensitivities show that, the size order of sensitivities is cave diameter, roof thickness and equatorial radius, polar radius, cave position. The bearing capacity of rock-socketed pile also had relation with cave shape; ratio of thickness to radius is a comprehensive affecting factor with cave thickness, equatorial radius and pile bottom area. The shape factor ?, bottom area size effect ? and notices of conceptual design are introduced to evaluate the bearing capacity of rock-socketed pile, which are verified by engineering examples. The field test results are in agreement with the model test results, and the karst problems not occurred after building completion.

Plane strain and conventional triaxial compression tests are performed on coarse-grained soil by the TSW-40 type true triaxial apparatus in Hohai University. The stress-strain relations and relationships between different strains of coarse-grained soil in plane strain condition are studied, including the relations between principal stress difference ? 1-? 3(or ? 2-? 3) and maximum principal strain ?1, principal stress ratio ? 1 /? 3(or ? 2 /? 3) and maximum principal strain ?1, spherical stress p and volumetric strain ?v, deviator stress q and deviator strain ? s, generalized stress ratio q/p and generalized shear strain ?s, maximum principal strain ?3 and maximum principal strain ?1, volumetric strain ? v and generalized shear strain ? s. The experimental results show that with the same ? 3, the ? 1-? 3 (or ? 1/? 3) curves in plane strain tests lie above those in conventional triaxial tests; the ? 1-? 3(or ? 2-? 3) curves with larger σ3 lie above those with smaller ? 3, while the ? 1/? 3(or ? 2 /? 3) curves with larger ? 3 lie below those with smaller ? 3; at the same σ3 and ? 1, the expansion in the direction of minor principal stress in plane strain condition is larger than that in conventional triaxial condition; at the same ? s, the larger the ? 3 is, the larger the ? v would be, and the volumetric strain ? v in plane strain condition would be larger than that in conventional triaxial compression condition at the same ? 3. There is a uniform hyperbolic stress-strain relationship in both plane strain and conventional triaxial compression conditions. It is proved that it is necessary to consider the anisotropy of elastic modulus E and Poisson’s ratio ? in the calculation of plane strain problems of coarse-grained soil by nonlinear elastic models.

The diatomite is a kind of strong structural soil, which has small density, large porosity, and high water absorption rates of dry rock. The shear strength of natural diatomite is large, but the structural strength lost occurs when the diatomite is disturbed by the external disturbance or weathering; so the diatomite slope is easily destroyed in the performance of landslide; thus to study the mechanical properties under large deformation is necessary. Using the characteristics of ring shear apparatus can study soil shear strength variation in a larger shear displacement conditions. this paper makes ring shear strength test study of the remolding diatomite, to obtain the stress displacement curves under different vertical pressures, which indicate that the remolding diatomite is of typical strain softening. According to the ring shear test results the remolding diatomite’s, shear strength and residual strength are obtained, and the soil mechanical properties are analyzed from the material composition and microstructure characteristics of the remolding diatomite, so as to provide reasonable parameters for diatomite landslide analysis and disaster prevention and control.

Laboratory tests are conducted to investigate geotechnical properties of sewage sludge in a sludge reservoir of a landfill, including organic content, water content, limit content, grain-size distribution, permeability coefficient, shear strength and consolidation coefficient. Test results show that the sewage sludge in the reservoir has much higher organic content and water content than the muddy soil. The average value of organic content is 45% and water content is 520%, respectively. As a result of biodegradation with a period of two years, both organic content and water content of the sewage sludge in the sludge reservoir show a decreasing trend with the depth. The sewage sludge had a very high compressibility, and the value of a100-200 is 7 MPa-1. The consolidation of the sewage sludge shows a nonlinear large deformation behavior; and the coefficient of consolidation is of the order 10-5-10-6 cm2/s, showing a significant decreasing trend with an increase of normal stress. The shear strength parameters are low with a cohesion of 0 kPa and an internal friction angle of 14.7°. The high organic content is the essential reason for the high values in water content, plasticity index and compressibility as well as the low values in permeability, consolidation coefficient and shear strength. The experimental results provide necessary parameters for the disposal of sludge reservoir and analysis of stability.

Saline soil may be treated with anticorrosion-wheat straw and lime for changing the properties of lesser strength and more serious deformation resulted from salt swelling and dissolved subside. Reinforcing range of specimen is in upper, middle, lower, and 1/3 section in the top and the bottom of specimen, and the cross section of wheat straw is of roundness, arch, quarter, any rolled size, which is five ranges. It has been proved that the lower reinforcing range and a quarter of cross section of wheat straw is suitable by means of triaxial shear test(UU) on reinforced saline soil with wheat straw and reinforced lime-soil with wheat straw. The reinforcing range and cross section of wheat straw effect greatly strength of saline soil with lime and wheat straw. The reinforcing contributes to cohesion of soil largely, and internal friction angle hardly, which have proved that wheat straw is feasible for reinforcing saline soil, and five reinforcing ranges in specimen and four cross sections of wheat straw always increase the shear strength and anti-deformation of saline soil.

Based on the non-equilibrium flow theory of multiphase porous media, the thermodynamic mixed theoretical model is proposed by Wei et al[1]. According to the model, the dynamic water-soil characteristic curve of unsaturated soil, which describes the incremental relationship between capillary pressure and saturation, is deduced. Within the context of the dynamic water-soil characteristic curve, an evolution equation of saturation in an unsaturated sample is developed. The equation describes well the variation of saturation with time in a multistep transient outflow experiment provided that the deformation of the matric of the unsaturated sample is ignored. On the basis of the evolution equation and the characteristic of the multistep transient outflow experiment, a new predicted method is proposed to determine the soil-water characteristic curve. For the low liquid limit silt and the low liquid limit clay, by comparing the theoretical simulation with experimental data in the multistep transient outflow experiment, it is shown that the saturation evolution equation can very well describe the constitutive relationship between saturation and time provided that the incremental step of matric suction is small. In addition, the calculated results of the soil-water characteristic curve agree well with the measured results of that measured by the laboratory combined system.

In order to investigate the factors which affect the cement improved high liquid limit clay dynamic resilient modulus and their variation laws, a series of dynamic resilient modulus tests were carried out by conducting dynamic-triaxial tests. The study demonstrated that dynamic resilient modulus values rise with the increase of confining stress, compaction degree and cement content, decrease with the increase of circular deviator stress and moisture content. To accomplish the purpose of analysis the relationships between deviator stress, bulk stress and dynamic resilient modulus, the dual-factor analysis of variance was utilized. The analysis demonstrated that both the deviator stress and bulk stress have significant effects on the dynamic resilient modulus. However, the deviator stress has more significant effects. Considering that dynamic resilient modulus is a function of deviator stress and bulk stress, with a brief analysis of adaptability of the present dynamic resilient modulus constitutive models, the three-parameters compound constitutive model which reflects the effect of bulk stress and deviator stress was utilized for experimental data regression analysis. A high coefficient of determination shows that the model which reflects the effect of bulk stress and deviator stress is accurate and credible. The prediction models used for different compaction degrees, moisture contents and cement contents were achieved; and they can provide parameters for the pavement design based on dynamic method.

In order to study the basic law of chemical slurry filled and reduced infiltration for weakly cemented porous media, the method of model experiment is taken to research on the permeability coefficient, porosity and compressive strength before and after grouting with different effective diameters and fineness modulus model material. The parameters of injection pump flow, slurry performance and hydrostatic pressure are controlled in the experiment, and six models are completed in all.The results show that: the grouting filling rate is between 9%-41% of each model material; and the rate gradually increases with the decrease of particle size and permeability coefficient. Permeability coefficient before and after grouting shows gradually decreasing trend with the decrease of effective diameter and fineness modulus, and the proportion of reduce increase gradually. The permeability coefficient of the model decreases significantly with the range of 84%-97% after grouting. Before grouting, the compressive strength of the model is low and close, after grouting, the compressive strength increments between 6-10 times, and the strength increments show gradually increasing trend with the decrease of effective diameter and fineness modulus.

In order to make good use of the standard penetration test (SPT) results on British Standard (BS) equipment during the Chinese geotechnical design, BS and Chinese Standard (GB) SPT equipment and results are analyzed to evaluate their correlation. The main difference between BS and GB equipment is that BS anvil quality is larger than GB; and different hitting energy and SPT values are caused. SPT analyzer has been used to measure the actual hitting energy of SPT on BS and GB equipments configured with different diameter rods. In order to analyze the correlation between SPT values of BS and GB, and establish correlation formula, the BS and GB energy ratio that actual hitting energy was divided by theory hitting energy are calculated. The conclusions are as follows: BS equipment is smaller hitting energy and the value of SPT is higher than GB equipment. The rod 50 mm in diameter has higher hitting energy and smaller value of SPT than the rod 42 mm in diameter. Correlation of the standard penetration test results on BS and GB has been set up. Therefore the data based on BS SPT equipments will be more reliable to be utilized in GB and also evaluate the appropriated geotechnical parameter in terms of GB SPT results.

The classical earth pressure theories can only calculate the pressure when the wall movement achieves the limit state. In order to match up to the practical situation, it is necessary to develop the earth pressure theories under nonlimit state. However, previous researches are only involved with the cohesion-less soil. Based on the existing results for active earth pressure of cohesive soil under nonlimit state, the relationship between the internal frictional angle ?，cohesion c and the wall movement is established according to Mohr circle of stress under the situation of intermediate active state. At the same time, considering the influence of wall friction angle ? and cohesive strength cw on the interface, the connection of cohesive strength c with wall’s displacement has been set up on the foundation of geometrical relationship in Mohr circle of stress. Finally, a new equation for determining active earth pressure of cohesive soil under nonlimit state is derived using horizontal slices analysis method. The value of calculation has an approximate agreement with the measured value of two model tests. The result shows that the proposed method has some theoretical significance in calculating active earth pressure of cohesive soil under nonlimit state and applied value in construction practice.

Based on the p-y curve method for plumb pile in sand proposed by Reese, a new p-y curve method and its corresponding finite element method for analyzing horizontal bearing characteristics of single batter pile are presented. Firstly, according to the mechanical behavior of the shallow soil near a batter pile, a three-dimensional wedge model is put forward to describe the passive region which is in the limit state. By using limit equilibrium analysis method, the expression of ultimate soil resistance of batter pile is derived. Then, the influences of pile angle and the friction between pile and soil are numerically studied; and the method for determining the initial modulus of p-y curve of batter pile is given. By modifying the p-y curve for plumb pile in sands proposed by Reese, the p-y curve for batter pile in sand is obtained. Using the virtual work principle, the finite element formulations for horizontal bearing analysis of single batter pile are deduced; and the iteration algorithm is put forwards. The corresponding program is coded by authors; and numerical examples are taken to illustrate the effectiveness of the method. Finally, a printed centrifuge model test of batter pile is analyzed by the presented method. The numerical results show fine agreement with those of model test.

Moment tensor method is introduced to analyze rockburst mechanism for deep tunnel, based on microseismic monitoring data of Jinping Ⅱ hydropower station. And some recommendations are proposed for two key issues in the analysis process: ①Restricted by the construction environment in the tunnels, tunnels are excavated in a straight line, and sensors can only be installed at the wall of tunnel or in the shallow boreholes. The calculation reliability of moment tensor is affected greatly on the numerical calculation; the coordinate rotation method is given to improve it. This method rotates the tunnel coordinate system to the new coordinate system, which makes the value of the direction cosine between the source-sensor vector and every coordinate axis less than 10 times, for every waveforms in the event. The ideal results can be got from a large number of moment tensor calculation. ②To get rockburst nucleation process, which calculates the moment tensor firstly, and decompose the moment tensor to the components of basic type, judge the rock fracture type based on the rule from the percentage of the components. But the rule proposed by Ohtsu is only applicable to all components by pulling, which is not suitable to tunnels of fast drilling; therefore, one rule is proposed to extend a more generally applicable state. Lastly, the complete method is established which used to research rockburst nucleation process by the moment tensor method. Analyzed microseismic data of Jinping Ⅱ hydropower station before rockburst happened by this method, the results show that the method can explain the evolution of rock failure mechanism better.

Subgrade settlement is a complex systematic process. Frequently used single point forecasting models can’t consider the correlation of settlement between the discrete monitoring points, so that it can’t represent the integrated deformation regularity of subgrade. A multivariable grey model named MGM(1,n), which is an extension of the single point model named GM(1,1), is introduced to solve the problem. According to the error of background value in the traditional multivariable grey model, this paper uses the functions with non-homogeneous exponential law to fit the accumulated sequences for every variable, reconstruct the calculating formula of background value, and gets a new multivariable grey model with optimized background value. Three monitoring points on the subgrade cross-section are analyzed by grey relational analysis theory. The corresponding MGM (1,3) model based on optimized background value is established; and the metabolism method is applied to predict subgrade settlement value. A case study shows that the forecast result of the proposed model is more precise and effective than these of the single-point grey model and the traditional multivariable grey model for predicting subgrade settlement.

The field geological exploration and survey are used to determine the form and property of Liujiaao loess landslide; in the western mountainous area of Henan province in-situ test and laboratory test are used to determine the influence factors and weakening law of strength of sliding zone soil; field monitoring are used to determine sliding depth. The activity history, formation causes, range and influence factors of Liujiaao loess landslide are analysed based on investigation and tests. Survey and analysis results show that, the sliding mechanism of Liujiaao loess landslide can be summarized as local ancient landslide revives caused by excavation of cutting and rainfall. For ancient landslide, the loess mass structure is relatively loose and shear strength is poor. When the front soil of ancient landslide is cut, ancient landslide loses the front supporting and retaining, and then the front of ancient landslide slips and failures along the sliding zone of interface of loess layer and gravel layer under the interaction of gravity stress and groundwater. According to the analysis of ancient landslide revival, Liujiaao loess landslide is pull-type landslide. After the front of ancient landslide sliding, the latter can slide successively and the crack develops in depth.

The analysis of discontinuities occurrence in rock mass is an important fundamental work for mechanical and hydraulic behaviors analysis of rock mass. Discontinuities with the same occurrence and different other properties have different mechanical and hydraulic behaviors. Therefore, there are defects in conventional method, due to that they partition discontinuities only according to their occurrence. A new method based on mutative scale chaos optimization algorithm is proposed for partitioning multivariate data for charactering discontinuities. The objective function is established based on the similarity measure between discontinuities; then, mutative scale chaos optimization algorithm is used to search the optimum solution. This new method can simultaneously divide discontinuities into several groups according to their multivariate properties. The accuracy of the new method is proved by artificial data. Finally, this method is applied to grouping of field discontinuity data with five properties; and reliable cluster results are obtained.

Aiming at the bearing capacity of rock anchorages for West River Bridge construction on Guangzhou bank slope, the engineering geological investigation, indoor and in-situ rock mechanical tests, borehole camera, sound wave tests, etc. are carried out to gain the rock mass geomechanical characteristics and the slope’s geomechanical model. Then anchorage tests are carried out to confirm the reliability of prestressed cables in-situ. The three dimensional numerical simulation is used to research the stability of the wall rock around anchorages when group cables prestressed and bearing load, as well as the distribution rule of prestressed cables’ resistance arranged at different positions in an anchorage. The results indicate that the rock anchorage system is stable when the West River bridge constructed and the displacements of the slope’s surface keep mm level; the prestressed cables’ anchoring force turn out uneven distribution and mainly concentrate in 2 m scope on the front of anchoring section; in the prestressed cable group of one rock anchorage, the concentration degree of cable resistance is first the angle cable, next the side cable, last the middle cable which from a large to small in turn. The overload experiments show that the rock anchorage system's ultimate anti-pullout capacity is not smaller than 8 times of the designed pulling load. Prestressed cables’ monitoring indicates that the axial force of cable is just stable during the whole period when the construction load increasing; and the middle cable’s axial force is less than the angle cable’s one. The research methods and results can be for reference in similar bridge constructions and anti- pullout projects.

Based on the Hewlett method for analyzing composite embankment with equal length piles, a three-dimensional hybrid soil arching analysis method is developed to explore the load sharing ratio of composite embankment with long and short piles under uniform pressure. The basic theoretical framework of three-dimensional hybrid arching analysis is established based on the vivid description of the stress concentration obtained from the finite element analysis. The soil arching effect coefficient is adopted to feature the incremental generation and the progressive failure of the arches, which changes with the increase of the length ratio. The equilibrium differential equation on the pile caps is established. The stress concentration ratios of the long piles and the short ones are calculated through solving system of equations including the equilibrium differential equation, boundary condition equation and relational expression of the two different soil arching effect coefficients. When the geosynthetics is taken into account, the reinforcement tension is calculated through the assumed deformed curves. And then a new equilibrium differential equation over the elevation of the pile caps is generated. Eventually, the results of centrifuge tests, in-situ tests and the finite element method are compared with those from the analytical method and are found to be in good agreement. Furthermore, parameter analysis is performed to evaluate the main influence factors on the soil arching. The analysis shows that the pile-soil stress ratio of the composite embankment with geosynthetics is significantly larger than that of the embankment without geosynthetics, especially when the cap coverage rate is relatively small.