With the large-scale developments in west China，the high geothermal and high geostress conditions have been encountered in growing number of tunnels. To study the thermo-mechanical characteristics of rock bursts occurred around tunnels with coupled high geothermal-geostress processes，the physical model with two-dimensional geomechanical loading system was developed. Based on the researches concerning the rockbursts prone similar materials，a tunneling excavation equipment and a thermal-stress loading system was also developed in this study. Four model tests，corresponding to four temperatures fields(20 ℃，40 ℃，60 ℃，80 ℃) under high geostress and with the lateral pressure coefficient of 2.0，were carried out to obtain the strains，acoustic emission features and deformation failure characteristics of surrounding rocks. The results show that during the range of 20 ℃–80 ℃，the degree of brittleness of and the accumulated elastic strain energy in surrounding rock increase with the rising of the temperature. The tangential stress and stress difference in tunnel wall increases，which creates more favorable conditions for rock burst. The higher the temperature，the smaller the deformation of surrounding rock before failure，and the bigger the released energy，the more fracture sources. Besides，the higher the temperature，the brittle failure of surrounding rock is more intense and occurs more suddenly，and the gradual process of rockburst is less seen，the block sizes of spalling rock and burst ejection are bigger. Hence，it can be concluded that the rockbursts take place more intensely with the increase of temperature(geothermal) under the coupled thermo-mechanical processes in a certain range of temperatures.

The freezing process of rock surrounding tunnels in cold regions is uni-directional along the radius，which is different from the uniform freezing in normal frost heave experiments of rock. A series of freezing experiments on saturated sandstone under uniform freezing and uni-directional freezing conditions were thus conducted in a closed system respectively. The test results show that the frost heave of saturated sandstone is uniform in different directions under uniform freezing condition，and that the variation process can be divided into three stages：a thermal contraction stage，a frost heave stage and a stable stage. However，under uni-directional freezing condition，the frost heave parallel to the freezing direction is much larger than that perpendicular to the freezing condition. Moreover，the variation process of the frost heave perpendicular to the freezing direction can still be divided into three stages as above. However，in the variation process of the frost heave parallel to the freezing direction，four stages are observed：a thermal contraction stage，a frost heave stage，a frost heave declining stage and a stable stage. The non-uniform frost heaving coefficient is in the range of 2.20 to 2.71 when the temperature gradient is in the range of 0.7 to 2.2 ℃/cm and the non-uniform frost heaving coefficient has the linear relationship with the temperature gradient. The greater the temperature gradient is，the greater the non-uniform frost heaving coefficient is.

The coal and gas outburst in crosscutting is the most serious dynamic disaster in coal mine in China. The relationship between the critical effective stress and the exposed area was deduced according to the fold catastrophe model. The maximum exposed areas of Fuxin Sunjiawan coal mine were presented under the different mining depth. The relationship between the exposed area and the critical effective stress was analyzed. The outburst coal seam at －1 100 m in Sunjiawan mine of Fuxin was studied. The experiment of the exposed area influencing the coal and gas outburst was performed using the triaxial outburst instrument designed and developed in-house and the coal briquette was put in the outburst instrument. The triaxial pressures were applied to the coal samples to simulate the stress environment of coal seam. The different exposed areas were simulated by changing the area of weak surface(30.19，34.21 and 38.48 cm2). The results show that the critical effective stress increases with the increasing of the exposed area. The calculated results agree with the experimental data，which verified the formula of the critical effective stress. The critical effective stress and exposed area are main factors of the intensity of coal and gas outburst in crosscutting. The distribution of coal powder after outburst has the characteristics of fluctuation. The outburst energy and intensity near the exposed face both increase with the increasing of exposed area and critical effective stress.

Rock masses can be regarded as the hierarchical structure of masses composed of blocks with structural planes and have the capability of storing energy at micro-level. Propagation of stress waves in rock masses generated by the external disturbances may trigger the release of internal energy and result in geologic hazards such as very large irreversible deformation，rockburst，engineering earthquake and so on. With the dynamic testing system of rock blocks developed in-house，the physical experiments to simulate the slipping of rock blocks induced by the impact disturbances were carried out to study the mechanism of irreversible displacements and slip failure，the influence factors and the conditions of threshold energy. Experimental results show that when the initial shear force is close to zero，the irreversible displacement may be induced by the external disturbances. The threshold energy of the irreversible displacement decreases with the increase of the initial shear force. When the initial shear force is close to the dynamic shear strength，the external disturbances may trigger slip failure. A dimensionless characteristic energy factor was used to characterize the threshold energy conditions of the irreversible displacement and slip failures induced by external disturbances. The physical relationship between the characteristic energy factor and the dimensionless energy conditions for pendulum-type waves was discussed. The comparison with experimental results shows that the energy factor can characterize the threshold energy conditions of irreversible displacements and slip failures induced by the external disturbances very well.

In order to arrest the extending cracks，the specimen with SCSC configuration has been improved，and a new type of specimen with VB-SCSC configuration having a V-shaped boundary was thus proposed in this paper. Under the impacting loads，the compressive stress waves propagate towards the crack tips，and the compressive stress waves restrain the propagating of cracks. The experiments were performed by using the impact load of low & medium speed and the crack propagation time and propagation speed were measured with the propagation gauges(CPGs). The VB-SCSC specimens with three angles of V-shaped bottoms 120°，150° and 180°(straight bottom) were tested，and the former two specimens have the arrest function on the propagating cracks. The finite difference code AUTODYN was applied in the simulation of crack propagation behavior，and the results agree well with the test results. The finite element code ABAQUS was applied in the calculation of stress intensity factors，and Freund?s function was applied in the correction of stress intensity factors. Finally，the dynamic fracture toughness was determined by using the crack initiation time and propagation time. The results show that the 120° VB-SCSC specimens arrest the propagating cracks well and are recommended for the future experimental study. The dynamic fracture toughness is inversely proportional to the crack propagation speed.

In order to study the large deformation control mechanism of surrounding rock of extremely loose coal roadway in gliding tectonics area，a large scale three-dimensional system of anchorage model was designed and the failure mechanism of support-surrounding rock system in coal roadway was analyzed by employing the combined method of field investigation，theoretical analysis，numerical simulation and physical simulation. Two laboratory physical models，with different control conditions to surrounding rock of roadway，were built respectively to understand the characteristics of stress development in entry surrounding rock，anchoring force of bolts and deformation of entry surrounding rock during roadway driving and mining. Two kinds of supports of bolting plus mesh were used in the laboratory test. One is the low tensioned bolts plus the steel-plastic mesh，the another one is the high tensioned bolts plus the combined meshes including the steel-plastic mesh and metal woven mesh. The results indicate that the supporting effect of bolts in the soft surrounding rock is weak，leading to the failure of surrounding rock in a short time under pressures，and then the large deformation appears gradually，causing the instability of the whole rock body surrounding the roadway. Upon the excavation of roadway forwardly，the radial tangential stresses in the shallow rock around roadway are reduced to different degrees. While for the roadway supported by high tensioned bolts and surface protection of high strength，the stresses in the shallow rock are obviously raised and the range of surrounding rock where the radial stress decreases is reduces is 0–1.64 m to 0–1.24 m. Besides，the stress increment in anchored surrounding rock is increased by 25%–51.8% after the influence of mining. Under the influence of mining，the deformation in the surrounding rock of roadway has an acceleration phase，in particular，the non-uniform large deformation in the surrounding rock between the bolts occurs. With the poor anchorage conditions，the shallow surrounding rock is constantly broken and partially dropped. Furthermore，the axial loads of bolt decreases slowly after a sharp rise. However，the rock under the second control conditions remains intact，and the axial loads of bolts increases steadily during the mining. Moreover，the surface displacement of roadway in the second test model is 31.9% less than that in the first one.

Jointed rock slopes under excavation unloading may studdenly lose the stability due to the high stress accumulated in the rock bridge of the slope. In order to simulate the influence of jointed rock bridge and different intermediate principal stresses on the strength and failure mode of rock slopes under excavation unloading，the uniaxial compression and true-triaxial unloading tests on granite specimens with different rock bridge length were carried out on the true-triaxial test system. The stress-strain curves，peak strength，crack propagation，failure mode，acoustic emission(AE) characteristics and peak intensity of AE were analyzed with the aid of high speed camera and AE system. The results show that，compared with uniaxial loading in the uniaxial loading the brittle failure is more obvious in the true-triaxial loading and unloading. With the increase of the length of the rock bridge，the peak strength of the sample，the energy released at the time of failure and the AE rate are all increased. Under different intermediate principal stresses，the compressive strength of the specimen increases with the increase of the intermediate principal stress but the peak value of the AE is reduced，which is resulted from that the lateral pressure caused by the intermediate principal stress makes the internal structure of the rock more compact and the micro-cracks difficult to develop. The influence mechanisms of rock bridge length and intermediate principal stress were revealed by the superposition method of intensity factor in fracture mechanics. The true-triaxial test can simulate the stress state of rock excavation unloading more realistically.

The experiments were carried out to investigate the failure process of marble which has cracks with infilling materials under uniaxial compression. The influence of the inclination angle of preexisting flaw and the different filling conditions on the failure process of rock were discussed through analyzing the characteristics of deformation evolution with the digital image correlation method(DIC) and scanning electron microscope(SEM). The results show that the change of the inclination angle of fracture affects the position of crack initiation，the crack angle and the strength of rock to some extent，while the improvement of the compressive strength is a result of fillers. Whether the fracture has filling or not，the failure modes of the rock are mostly because of the combination of shearing stress and tensile stress，but the damage patterns are different. On account of the fillings，the primary failure mode of rock is the wing crack macroscopically，and the shear failure is more obvious mesoscopically. When there is no fillings，two dominant failure modes of the wing crack and anti-wing crack are observed macroscopically and the tensile failure is more obvious mesoscopically.

In order to investigate the energy dissipation characteristics of rock material during the tensile failure process，a series of single loading-unloading tests including Brazil split test，point load test and three point bending fracture test(semi-circular bend，SCB) were conducted to red sandstone on the testing system MTS 322 and MTS Landmark. The total input energy，elastic energy and dissipated energy under different unloading levels can be obtained with the graphic method of area integration. The relationships of these three energy parameters and its variations with the increasing of unloading levels were also analyzed. The results show that the total input energy，elastic energy and dissipated energy of rock specimens under different unloading levels increase quadratically with the increasing of unloading level. There is a linear relationship between the elastic energy，dissipated energy and total input energy at each unloading level，which is independent of the loading level. The internal elastic energy of rock sample at the peak strength point can be calculated according to this linear function. The energy storage coefficient(the ratio of elastic energy to total input energy during the loading process of rock specimen) is defined according to the linear relation of energy storage.

Fail to prepare the fractured rock samples with complex structures has long been hampering the mechanical experiment on the structural surfaces of rock mass. The fractured rock specimens with rough joints  were manufactured using the 3D printing technique. Then uniaxial compressive tests were conducted on the rough discrete fractures network(RDFN) models，discrete fractures network(DFN) models and intact rocks with varied scale sizes. The results show that 3D printing technology can provide the opportunity to produce both the DFN models and RDFN models. A serials of rock specimens with the same internal structures and scale sizes could be efficiently established. According to the uniaxial compressive results，the elastic modulus and uniaxial compressive strength(UCS) of the printed fractured rock specimens were apparently lower than those of the intact rock specimens. The uniaxial compressive behaviors of RDFN and DFN models varied with the increasing of scale sizes. Different fractured patterns were also found after compressive failure. When considering the joint roughness，the elastic modulus and UCS of RDFN models were higher than those of the DFN models. The uniaxial compressive behavior of fractured rock mass would be underestimated if the joint roughness is ignored.

At present，the support and surrounding rocks in the model test cannot meet the coupling relationships of stiffness，strength and stability，and the features of three-dimensional loads of support are also neglected. To ensure the accuracy of experimental results，a mechanical model of support under three-dimensional loadings was established，the effect of the squeezing force between the supports and the lateral force behind supports were considered. A two-prop shield hydraulic support was developed and the parameters of real-time performance were obtained with the high precision displacement/stress sensors. The properties of model support were tested. The results show that the model support has the resistance range of 0.046 to 0.528 kN，which can adjust the output pressure and the diameter of column to achieve the designated working resistance. The stiffness of model support in the resistance increasing phase is basically unchanged and is high enough to resist the dynamic impact. The critical slip angle of the support under triaxial forces is smaller than that of the uniaxial compression，but the squeezing force between supports and the lateral force behind supports are suppressed to a certain extent. Then the model supports was applied to the experiment of 3132 working face，Lvshuidong coal mine. The working resistance of model support is 22.42 MPa，the error is less than 5% compared to the measured values from the field. The drilling observation instrument was used to detect the goaf and the performance of model supports was found to be in line with the field shields in adjusting the surrounding rock structure and stress field.

To obtain the state of in-situ stress during the exploration of dense gas reservoir under Tarim Basin，the anelastic strain recovery(ASR) and the methods of drilling induced tensile fractures(DITF) were applied to measure the in-situ stress at depth of 7 km. The results show that the maximum principle stress is close to vertical and the medium and the minimum principle stresses are close to horizontal in SN-X well at 6 293–6 955 m depth. The orientation of maximum horizontal principal stress is NE51°–NE79°. The normal faulting stress regime exists in the inner Tarim Basin caused possibly by the stress releasing after the orogenic period or the escaping structures of Tarim basin by the long distance effect of Himalaya collisional orogeny. The effectiveness of ASR method at the ultra-depth was confirmed by the close results from the ASR and DITF methods. The ASR method has the advantages of low cost，high efficiency，and no depth and temperature limitation，and hence，will have broad prospect of application at ultra-depth in scientific drilling，unconventional oil and gas exploration and geothermal development.

In order to study the parameters of fracture toughness and the propagation behavior of mode I crack under blasting loads，crack propagation gauges(CPGs) and single internal crack circular disc(SICCD) specimens were first applied in the tests of fracture toughness. The specimens of PMMA and the testing system of oscilloscope and ultra-dynamic strain amplifier were employed. Numerical models were established with the dynamic finite difference code AUTODYN and finite element code ABAQUS. The crack propagation velocity，dynamic initiation toughness，propagation toughness and fracture parameters of mode I crack were obtained through the experimental and numerical methods. The experimental results show that in the process of crack propagation，there is a cusp point on the propagation path and the phenomenon of crack arrest occurs at the cusp point. When the crack restarts to crack again，the speed will increase. CPGs monitor more accurately the propagation behavior of crack. The fracture toughness and other dynamic parameters were obtained with the experimental-numerical methods. The preliminary analysis shows that the dynamic crack arrest toughness is greater than the dynamic initiation toughness and the dynamic propagation toughness under blasting loads.

The cyclical fluctuations of water level in the reservoir area combined with the rainfall increase the probability of reactivation or even instability of existing and potential landslides on both banks of the reservoir area，which threatens the safety of life and property of the residents in the reservoir area. The method of calculating the regional landslide stability considering the characteristics of rainfall and water level fluctuation was thus introduced. The unsteady equation of motion of phreatic water with inclined impervious bed was solved with Boussinesq method to derive the approximate analytical solution of groundwater level in bank slope when the reservoir water level drops uniformly. The transient rainfall infiltration model and the three-dimensional slope stability calculation model were adopted to calculate the regional landslide stability according to the different rainfall duration and intensity. Wanzhou bank of the Three Gorges Reservoir area was presented as an example with the data and parameter acquisition method in stability evaluation introduced in detail. Three different conditions were compared and calculated. The results show that the predicted results in simulation considering the different reservoir water levels and rainfalls reflect the spatial distribution characteristics of slope stability in the study area to some extent. The stability of the reservoir banks in the study area is more responsive to the rainfall than to the changes of water level of reservoir.

Analysis of surface deformation induced by underground mining can provide guidance for figuring out the range of surface deformation and guaranteeing the safety production of the mine. The west zone of Chengchao iron mine was investigated through the comprehensive analysis of monitoring data from 2006 to 2017 and the trend of ground deformation after surface collapse was studied. The effects of rainfall on the surface deformation and rock movement were discussed based on the collected hydrogeological and meteorological data. The results show that the surface deformation had been extending constantly outward since the ground collapse. From the moment of ground collapse to the end of September 2008，the surface deformation expanded with the collapse area as the center，and evenly expanded in the hanging wall and footwall. However，in December 2014，the footwall deformation proved significantly greater than the hanging wall with the center of deformation area shifted to the mined-out zone. The depth and extent of the funnel-shaped surface deformation were expanding unceasingly with the time passing. In the north-south direction，the expansion of deformation funnel in the north was greater than in the south. In the east-west direction，the center of the collapsing funnel kept moving eastward. According to the mechanism of rock movement，the deformation area of deep rock mass is divided into the toppling-sliding zone，the toppling-cracked zone and the bending deformation zone. In the toppling-sliding zone，the deformation of the surface is maintained at a large speed after the accelerated deformation stage. In the toppling-cracked zone，the surface deformation restores the stability after the accelerated deformation，and the deformation of the bending deformation zone is maintained at a small rate. The monitoring points around the mined-out area have obvious deformation acceleration before the surface collapse. Surface deformation is related to the rainfall intensity and rainfall duration，which has two peaks in February to March and May to August respectively.

Daguangbao landslide(DGB landslide) is the largest landslide triggered during Wenchuan earthquake 2008. It is also one of the most catastrophic landslides around the world during the past 100 a. DGB landslide is in the area of carbonate rock and about 5 km away from the seismogenic fault and 85 km from the epicenter. However，this landslide changed the landforms of a region about 10 km2 with a volume of 11.59×108  m3. Additionally，DGB landslide exposed a main scarp with an average height of 600 m(maximum height of 850 m)，an open tension flank in the north with a length of 1.5 km and a sliding surface in the south with a length of 1.8 km. The river in front of DGB Mountain was filled up with a dam of 800 m in height. These incredible landslide features had attracted the wide concerns. Based on the previous studies and our observations in the past 7 years，the geology setting and earthquake-induced ground shaking were presented in detail in this paper. The distribution and properties of the 112 large-scale landslides triggered by Wenchuan earthquake were studied，and it was found that a bedding fault under Mt. DGB and the amplification of seismic ground motion in DGB area were the precondition of DGB landslide. Petrologic studies on the slip zone of DGB landslide microscopically were carried out and macroscopically and experimental investigation of the rock properties was performed. The results indicate that the rock mass of slip zone dilates during the earthquake. Site observation indicates that the dilatation of slip zone is resulted from the impact loading during the earthquake due to the amplification of seismic shaking. The shear strength of the materials in the slip zone was estimated. The results indicate that the reduction of shear strength due to rock fragmentation could not result in a sudden failure of DGB landslide. Recently，the ground water in Mt. DGB was investigated. The site evidence indicates that Mt. DGB has rich ground water with the well-developed vertical drainage before the earthquake. It is hypothesized that the vertical drainage is connected instantly during the earthquake，and that the ground water swarms into the dilated bedding fault which induces water hammer within this layer. A model of water hammer force in open tension crack was established，and the water hammer pressure was calculated. The results show that the maximum pressure is 20 MPa when the height of water head is assumed in a range of 70–360 m. It is concluded that water hammer pressure reduces the shear strength suddenly，and that the landslide is initiated with the high initial velocity. Finally，an improved model of DGB landslide mechanism was proposed.

Rock is essentially a kind of heterogeneous material and its mechanical properties are controlled by pore microstructures. In this paper，the fractal dimensions，pore size distributions and shape factor distributions of micro-CT images of different rocks were calculated using the image morphology algorithms. With the REV of digital images，the deformation simulation experiments were performed using FEM and the effects of microstructures on rock deformation were investigated. The results show that the pore size distributions differ significantly among these rocks of which both skeletons and pores have fractal characteristics，and the round pores account for little. Due to the restraint on the two ends of rock sample under uniaxial loading，rock failure does not firstly emerge at the sample end，but at the middle of rock sample where an X-shaped conjugated plastic shear zone emerges，and it develops continuously until the rock sample is destroyed. The highly uneven distribution of plastic deformation zones and the distinctly internal stress concentration occur due to the irregular pores. Along the loading direction，rock has a distinct displacement mode with large lateral deformation，and the displacement gradients of transition regions of the deformed belts are quite large. An arc-shaped elastic deformation zone below the X-shaped shear zone is produced. The effective elastic modulus of rock has a good correlation with the porosity and fractal dimension. With the increasing of porosity，the effective modulus decreases almost exponentially，indicating that porosity has a remarkable influence on the mechanical properties of rock. The larger the pore fractal dimension is，the smaller the elastic modulus.

The roadway intersection linking 1100 central pump station and water tank of Huafeng coal mine was investigated in order to solve the supporting problem of roadway intersection at the depth of 1 000 m. The key factor affecting the deformation and failure of intersection was revealed to be the rheological perturbation effect of rock based on the results of field investigation，experimental tests，rheological experiment on rock and theoretical analysis. The supporting technology of concrete filled steel tube was put forward，and the repairing scheme of the intersection support based on the composite support with concrete filled steel tubes was designed. The results of the finite element analysis，the theoretical calculation and the second rheological perturbation experiment，indicate that the bearing capacity of the composite support meets the stability requirements of the surrounding rock under the action of dynamic pressures. The composite support scheme employing the concrete filled steel tubes has been stable for 5 years. Overall，the intersection is stable and the support deforms slowly. The research indicates that the deformation mechanism of the intersection at 1 000 m deep is complex and the support structures are easy to damage due to the rheological disturbance.

The current researches on the pile spacing of stabilizing piles mainly focus on the two-dimensional landslide model with a single homogeneous layer. However，substantial evidence indicates that a large number of landslides in the actual engineering practice have the characteristics of multi-layer structure. A three-dimensional multi-layer landslide model was developed to analyze the formation of the soil arching behind the piles and the four-stage process of soil arching. Furthermore，an improved strip method was presented based upon the presented three-dimensional multi-layer landslide model. The most dangerous sliding body can be obtained via the improved strip method accordingly. The distribution function of the driving force and the distribution function of soil resistance in landslide mass were introduced to accurately describe the stress distribution in the soil arching. In view of the balance condition of arching in the most dangerous sliding body，the strength condition of the unified strength theory and conditions for soil behind pile to play a role，two methods of calculating the minimum pile spacing and correspondingly two layout schemes for stabilizing piles were put forward. The calculation results of the Houba landslide and the Bazimen landslide show that two optimized layout schemes of stabilizing piles reduce the stabilizing pile ratio at least 12% than the conventional layout scheme of stabilizing piles.

黄土在我国分布广泛，且大多都具有显著的结构性，黄土工程中又有许多平面应变问题，深入研究平面应变条件下结构性黄土的本构关系在理论研究及黄土工程应用中显得尤为重要。为了更合理地描述平面应变条件下结构性黄土的应力–应变关系，基于临界状态土力学理论，提出一个能够反映平面应变条件的结构性黄土本构模型。在模型建立过程中，引入结构屈服压力，依据平面应变试验结果直接确定固定屈服面和加载屈服面，并验证选取塑性体应变 为硬化参量的合理性，使本构模型更符合工程中土体的实际受力过程。模型中各参数物理意义明确，可由等向压缩试验和平面应变剪切试验求得，通过试验曲线与模型计算曲线的对比可知，所建立的本构模型可以较合理地描述平面应变条件下结构性黄土加载条件下的强度、变形特性，具有很好的应用前景。

The longitudinal vibration of single pile with cushion cap in three-dimensional soil was derived according to three-dimension soil modeling around pile and fictitious soil pile. Firstly，the cap-pile-soil system was discretized into the finite segments considering the stratification of the surrounding soil and fictitious soil pile. Then the impedance function of displacement at the top of pile was obtained with the method of impedance function transfer. The analytical solutions of displacement of the system of cushion cap and pile in frequency domain were obtained. The semi-analytical solutions of displacement of the system of cushion cap and pile in time domain were obtained with Laplace transform. The parameters of the surrounding soil including the shear wave velocity，damping coefficient and Poisson′s ratio were analyzed. Meanwhile，the parameters including the shear wave velocity，depth and thickness of the hard interlayer in the multilayered soil were analyzed. Compared with the damping coefficient and Poisson′s ratio of surrounding soil，the shear wave velocity in surrounding soil has the greater effect on the longitudinal vibration of cap-pile system. The upper soil layer affects the longitudinal vibration of cap-pile system more than the lower soil layer. Finally，the theoretical calculated results were compared with the measured data from field monitoring, which confirmed the sensibleness of the three-dimension soil model of the pile with cushion cap.

In order to describe the anisotropy and the stress direction dependence of geomaterials，a new stress tensor，named the equivalent stress tensor，was defined on the basis of the internal stress of granular materials，so that the stress magnitude，fabric level together with the directional relationship between the stress and fabric can be described. The isotropic constitutive models were used to describe the mechanical properties of particle interfaces and the equivalent stress was used to describe the contact stress between particles. The existing isotropic models can be modified into the anisotropic ones with the equivalent stress method. A new non-linear model was thus established which takes the anisotropy and the stress direction dependence of geomaterials into account. The new model has only three parameters which can be determined by the rigorous theoretical calculations and simple laboratory tests. The nonlinear model predicts accurately the anisotropic shear deformation and peak strength of specimens from the results of shear tests with the principal stress in fixed direction.

The existing theories for consolidation of band-shaped vertical drains were usually derived by converting the band-shaped drain into an equivalent circular drain using various equations. A common disadvantage of these studies is that either the circumference or the section area or even both of them of the band-shaped drain cannot be kept unchanged before and after conversion. Consequently，the actual amount of water flowing into and flowing out of the band-shaped drain cannot be reflected by the equivalent circular drain，which will inevitably lead to the misunderstanding of its consolidation behavior. In this context，a new equivalent annular drain is proposed to overcome the above disadvantage of the conventional circular drain. By considering three variation patterns of the horizontal permeability coefficient within the smeared soil zone，general analytical solutions are derived for the consolidation of band-shaped drain subjected to depth-dependent stress caused by time-dependent surcharge loading. Based on the general solutions，the detailed closed-form solutions are further derived for the cases of linearly distributed stresses along depth caused by instantaneously loading，linear loading，multi-stage instantaneously loading and multi-stage linear loading. Then，the effect of the annular drain is investigated by comparing its results to that of the circular drain. The results show that the circular drain is a particular case of the annular drain when the area reduction coefficient is taken as 1. The average degrees of consolidation predicted by the present solutions are mostly close to and slightly larger than that predicted by the Fellenius and Castonguay(1985) method based on the circular drain with equal cross-section area. The average degree of consolidation predicted by the annular drain is less than that predicted by the circular drain，moreover，the former is getting closer to the latter with the increasing in the area reduction coefficient. The difference in the average degree of consolidation predicted by the annular drain and circular drain diminishes with the reduction in the permeability of the band-shaped drain.