Focusing on characteristics of strong excavation unloading of high sidewalls of multi-cavern group under complicated geological conditions，an intelligent and dynamic design method is proposed for the stability analysis，design and construction of large cavern group. The method aims at the safe and economic construction for the large cavern group under complicated geological conditions. It considers the entire system?s process from recognition of geological conditions，back analysis of in-situ stress field，understanding of deformation and failure mechanism of surrounding rock of large cavern group，stability analysis，global optimization of control measures of the stability such as excavation procedure and support parameters of cavern group，and dynamic adjustment of the excavation procedure and support parameters during the construction. The method has been in good practice of design and construction of underground powerhouse at Jinping II hydropower station. The results show that it is reliable information，intelligent and scientific method for design and construction of large cavern group.

Supported by project of Jinping I hydropower station，based on field measurement data，quantitative analysis of rock mass block index was performed with systematic synthetical methods including contrast analysis，statistical analysis and deduction of relativity. As a result，the critical values of rock mass block index were established for integrated rock mass，block rock mass，subblock rock mass，mosaic rock mass and cataclastic rock mass. Compared with the same index of early geological engineering，they showed consistency as well as difference. The research findings enriched the study content in this field. These methods used to get quantitative rock mass block index are potential reference for the establishment of other criteria.

This paper gives a review of the nonlinear theoretical rheological model(TRM) in which some or all of the rheological parameters are variables versus stress，time or both of the two. Various kinds of TRMs are summarized，and different methods of obtaining creep equations of the nonlinear TRMs are categorized into three basic forms：(1) Constitutive equation of the nonlinear part is given first，followed by the deduction of the whole model?s constitutive equation and creep equation. (2) Constitutive equation of the nonlinear part is given first；creep equation of this part is then deducted；and the whole model?s creep equation can thus be obtained by superposition method. (3) Creep equation of the nonlinear part is given directly and creep equation of the whole model is obtained by superposition method. A doubtful and even wrong method is also pointed out to prevent further mistakes.

To study the effect of saturation on the tensile strength of rock，dry and saturated rings of 30 mm in thickness，50 mm in external diameter，and 0–20 mm in internal diameter were conducted by Brazilian splitting test for four rocks. The broken discs after Brazilian splitting were point loaded. Dry and saturated cylindrical specimens were uniaxial compressed. Based on the statistical analysis of Brazilian splitting results of discs，the average strength of repeated test in 5 times may eliminate the dispersion from specimens except marble. The softening coefficient of Brazilian tensile strength is higher than and linear relative to that of uniaxial compressive strength. The influence of saturation on the Brazilian tensile strength mainly results from the high compressive stress in the neighbourhood of the load point and the cohesion decrease. Correspondingly，the splitting strengths are nearly the same for dry and saturated rings with 20 mm in internal diameter，which means that the compressive stress does not influence the ring splitting greatly. An exponential equation is proposed for rings to describe the relation between Brazilian splitting force and its inner diameter；and the Hobbs? equation based on the elastic mechanics has great difference from the experimental results.

A series of pre-peak unloading tests on sandstone from Chongqing Yuzui under the range of initial confining pressure between 10 MPa and 130 MPa have been carried out，in order to analyze rock deformation behavior，failure deformation，peak strength and residual strength criterion，the evolvement property of dilatancy parameter during the process of unloading. The conventional triaxial compression tests of sandstone have been also performed. The results show that：(1) The triaxial compression tests performed under different confining pressures discover that the stress drop of the stress-strain curves does not appear when confining pressure reaches above the value of 130 MPa；so it can be considered as the transition point of brittleness and ductility. (2) Under conventional compression，the dilatancy amount at the pre-peak of deviatoric stress is smaller compared with post-peak；while under unloading stress path，the sample exhibits greater dilatancy amount at pre-peak of deviatoric stress. (3) Under the same initial stress，the variation in stress required for rock unloading failure is comparably less than that of triaxial compressive process，which reveals that unloading stress path make sandstone sample more prone to failure. (4) Under the same confining pressure，the rupture angle of unloading failure is greater than that of loading failure. (5) Shear strength parameters have been evaluated by Coulomb laws；it is found that the cohesion c decreases，but the inner friction angle increases during unloading；under the two loading stress paths，the cohesion c decreases greatly and the inner friction angle has a little change at the residual deformation stage. (6) The restriction on the behavior of dilatancy by confining pressure is significant，when the confining pressure is higher，the peak dilatancy angle would be smaller，the dilatancy angle increases quickly to the peak after the beginning of unloading；the peaks of deviatoric stress and the dilatancy angle exhibit a time asynchrony；moreover，the former lags behind the latter；the dilatancy angle under unloading stress path is greater than that under conventional loading stress path and needs smaller plastic shear strain to arrive at the peak dilatancy angle，which shows that the unloading stress path makes the dilatancy property more significant. These conclusions have revealed the unloading mechanical properties of sandstone under high geostress and provided reliable theoretical reference for the numerical simulation about excavation and design for the stability analysis of deep-buried access tunnel in West China.

The morphology of joint surface is one of the key factors affecting shear strength of joint. Relationships between morphology of joint surface and shear strength of joint are studied experimentally. Shear tests of natural rock joint under different normal stresses are conducted with RYL–600 rock shear-rheological instrument，and the relationships between shear stress and shear displacement under different normal stresses are obtained. Topographical measurements are carried out prior to and after shear tests with TALYSURF CLI 2000；3D scanning images of joint surface are obtained. Relationships between shear strength of joint under different normal stresses and morphology characteristic evolution of joint surface is analyzed. The weighted average of the mean profile angles of rock joint surface is firstly computed. It is found that the peak shear strength increases with normal stress；and the average of the mean profile angles decreases with the increase in the number of times of shear tests. It is shown that the shear strength of joint is concerned with normal stress and weighted average of mean profile angles of joint surface.

The parameters of each rock mass class provided in Standard for engineering classification of rock masses (GB50218–94) have little relation with rock masses classification and need to be verified. 920 samples of in-situ deformation testing values were collected and statistically analyzed class by class；then the scope of deformation modulus of each class was given；and the statistical values were compared with the values in GB50218–94. Except for in-situ testing values，geological suggestion values of rock masses deformation moduli were also collected and analyzed class by class；and the statistical results were compared with the suggestion values in Code for engineering geological investigation of water resources and hydropower(GB50487–2008). Researching results indicate that the boundary between class II and III in GB50218–94 needs to be reduced；and the boundary between class IV and V in GB50218–94 is inconsistent with the value in GB50487–2008. It?s suggested that the geological suggestion values also should be included in GB50218–94 to improve its practicability.

The anchor cables，which are concentrated tension and full-bonded type，are used to be applied in national important hydropower projects widely. Whether would these cables be a time-bomb of those national important hydropower projects? It?s a big problem bothering all the engineers. So the problem is studied by an in-situ cable excavated experiment which had been worked underground for twenty years at Manwan hydropower station. Based on experimental results，the research is done through five aspects. There are the features of anchor head，anchor retraction quantity，rust prevention effect，inner fixed anchor and the chemical and mechanical properties changes of tendon. Finally four results are achieved. The first one is that full-bonded art is a good type to prevent the whole anchorage failure just because of part damage. The second one is that cement grout is a good staff to prevent the steel strand corroding. However，its effect is not very well to prevent the corrosion growing on anchor head part. The third one is that there is no cracks found at inner fixed anchor. That is good fact to prove that inner fixed anchor can work well in a suitable prestress just using cement grout. The last one，the chemical and mechanical properties changes of tendon after twenty years? work are still in the acceptable range of standard.

Tests of microscopic characteristics and seepage properties were done respectively，using different coals from the typical coal mines. The results show that specific surface area and adsorption/desorption capacity of outburst coal is higher than those of delay outburst coal and non-outburst coal，and delay outburst coal at intermediate between the two others. Adsorption capacity of outburst coal is strong，desorption velocity is very fast too. It can form very high gas pressure which enhance destructiveness of coal-rock. Permeability of non- outburst coal is about 4 times higher than those of other coals at the largest department. If coal?s seepage properties are excellent，methane moves very easy in the coal seam in which gas storage condition is very poor and methane detaches very easy from it. Conversely，the outburst risk may increase. It is shown that the seepage property is an important index of the outburst risk of the coal seam. In a word，the seepage property and microscopic characteristics of coal are closely related to which the coal has strong adsorption/desorption characteristics，relatively poor seepage property，rather low strength，and is easy to fail. So it has very high outburst risk.

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For purpose of accurately sameness between numerical simulation and practically mechanical behaviors of cavern，key principles of numerical simulation method for underground caverns are described firstly. Then，right ways of rock constitutive model recognition and parameter recognition are introduced in detail，taking Jinping II hydrpower station underground caverns as an example. On one hand，model recognition is carried out and checked from some aspects，including failure mode analysis of rock，deterioration rule of mechanical parameters，fitting of testing curves，simulation of testing tunnel，etc. On the other hand，six times dynamically intelligent back analysis of rock mechanical parameters considering spatial distribution multi-information have been done，which provide actually equivalent parameters for 3D simulation. With reasonable constitutive model and exact parameters，the calculation result of 3D numerical simulation about caverns excavation exposes reasonable deformation，redistributed stress and plastic zone of surrounding rock，which can be used to explain special mechanical behaviors of surrounding rock，such as large deformation of powerhouse?s upstream，failure of rock and shotcrete，circularity cracks of busbar tunnel，local slumping of fork rock，etc. What?s more，based on the accumulation and experiences of Jinping II hydropower station underground cavern?s study，some supporting issues in design，such as high sidewall with dense joint，position with concentrated stress and groundwater in surrounding rock，are also discussed，which provide legible instance and cues for study and design optimization of large underground engineering.

The computational accuracy and efficiency of the conventional simulation method cannot meet the need of information design of rock slope. Based on the new idea of “dynamic simulation”，the block element method is proposed to dynamically simulate the excavation process of rock slope. Firstly，the “cutting algorithm” is put forward to identify the block system，in which the new discontinuity or excavation is introduced into the model by cutting the current block system，and the deletion of discontinuity is implemented by block mergence. So the variable block system during excavation can be identified dynamically，and the efficiency of the identification algorithm is improved. After that，the calculation of the excavation load during the dynamic simulation is discussed in detail and implemented in the block element method，in which those problems caused by the artificial pre-imbedded planes and their stiffness in modeling the excavation procedure are totally avoided. Finally，the newly proposed method is verified to be accurate and efficient by a simple numerical example and an engineering example.

Based on the methods and technologies of coal-bed methane(CBM) exploration by coal seam in hydrofracture on the ground，and the desorption characteristic of CBM after the effects of high pressure water injection into the coal mass sample，a great deal of experiments about CBM desorption features in coal sample after water injection have been designed. Through these experiments，desorption features of CBM after the effects of high pressure water whether or not have been illustrated；and the comparison of desorption whether water injection or not could be showed in order to apply in actual coal seam. The experimental equipments which acted on our own manufactured devices including adsorption，water injection and desorption，all of the necessary experiments have been conducted. During the process of experiments，adsorption，high pressure water injection，desorption experiment are conducted one by one. In order to acquire the desorption law of coal samples at different conditions，the combination experiments of coal，gas adsorption pressure and desorption which injected water or not have also been studied. The results show that：(1) At the same balanced gas adsorption pressure，the natural desorption percentage of poor coal sample #1–1 is 56.17% and exceeds the blind coal sample #2–1，the value of which is 51.50%. The result is equated to the actual coal mine. (2) The desorption percentages of coal mass containing gas are mostly affected by whether water injection or not. When the water injection pressure was equal to gas adsorption pressure，the desorption percentages of the coal samples #1–1，#1–2 and #2–1 are 40.15%，47.17%，27.09% respectively，and the percentages are only 50%－70% of the natural state. The most affection one is the blind coal sample #2–1，and the least one is the poor coal sample #1–2. (3) Followed by the pressure of water injection increasing，the ultimate desorption percentages gradually decrease more or less at nonlinear law and go to remain stable at last. The percentages of desorption will tend to stable if water injection pressure reached a limited value. (4) Time effects of desorption are related to water injection. In natural state，desorption could be stable at very short time，but after water injection the balance will need long time.

Based on the Xi?an metro tunnel passing through active ground fissure zones，the interaction between tunnel structure and soil under metro tunnel which orthogonally crossing the ground fissure belt is studied by a physical modeling experiment. When the upper and lower plate dislocate relatively，the longitudinal strains of structure，the relative displacement at the bottom of the tunnel and the peripheral soil pressure are analyzed. The test results indicate that the load transfer mechanism of the interaction between the tunnel structure crossing the ground fissure and soil contains four factors，specifically，the structure stiffness effects，supporting action of underlying layer，the friction force between tunnel structure and soil，and the effect of contact between the hanging wall and the footwall. According to the deformation behavior and the strain variation rule，the mechanical model for the interaction between tunnel and soil is created under the void state which is at the bottom of the tunnel. The research results may provide references for the structure design of the tunnel when the Xi?an metro tunnel crossing the ground fissure. Through the comparison of several different sections of tunnels，two points of views are come up. The first one is the horseshoe tunnel should be utilized in preference to other tunnels when the metro tunnel orthogonally crossing the ground fissure belt，which can improve the structure stiffness. The second one is controlling the crack of the concrete tunnel which located in the lower plate of the ground fissure at the same time，and coping with the waterproof treatment. 

For studying the deformation and failure modes of tunnel surrounding rock systematically under different continuum media，model tests have been performed on artificial cohesive material and artificial sandy materials. Barite powder，quartz sand and vaseline are the key ingredients of the cohesive similar material. Two types of sandy material made of quartz，and quartz+barite powder are tested respectively. Pressure cell，displacement gauge and non-contact precision measurement are used to monitor the surrounding rock response after excavation，the stress and deformation of the surrounding rock induced by tunnelling and further loading. For cohesive material in the process of step loading，failure first occurs on both sides of the tunnel and then at tunnel crown. According to the displacement and stress monitoring results，in response to the increase in load，the size of plastic zone increases as well. It also reveals that once the plastic zone develops，the rate of deformation in the tunnel surrounding rock will increase. Tunnel excavation in the sandy quartz material does not possess self-stability. However，for sandy material made of quartz and barite，the tunnel remains stable after excavation. For this mixture material，with the increase in applied pressure，failure arch first appears at the tunnel crown which follows the shape of a parabola curve. The arch foot then moves towards the sides of the tunnel. Stability is achieved when it reaches the central axis of the tunnel；at this point，the collapse arch sliding surface is similar to the Platts theory. This series of model tests，which allow the observation of the deformation failure modes for tunnel under different continuum media，provide significant information for the determination of tunnel supporting parameters.

Combining with the dynamic finite element method，the vector sum analysis method(VSAM) which is based on the vector characteristic of force and true stress field，is used in seismic stability analysis of slope；and the dynamic stress field at any moment under seismic loads are obtained；so the time-history curves of safety factors of slope can be obtained easily；and the whole stability state of slope can be evaluated. And then，the method is applied to a high steep rock slope；and based on the static stability analysis of slope，the deep slip surface governed by the weak discontinuities is analyzed under seismic loads. Seismic responses of 63 % and 2 % probability of overloads in 50 a are taken into account in dynamic stability analysis of the slope. The calculating results show that the dynamic safety factors are 1.86 and 1.66 under small and big seismic loads，respectively. The seismic characteristics and dynamic stability of slope can be well simulated with VSAM，so as to provide a practical approach for dynamic stability analysis of slope.

Acoustic emission(AE) is an important means to study rock internal micro-deformation and failure mechanism，the Kaiser effect is one of the common used methods of geostress measurement which is not standardized now. In many cases the Kaiser effect points are not obvious. In order to improve the ability of identifying Kaiser effect point，uniaxial compressive AE experiments of 21 rock samples are carried out. The samples derived from Ordos basin and consist of conglomerate，sandstone and mudstone. Comparison of the influence of lithology，loading mode and AE parameters on Kaiser effect point recognition are made. The results show that conglomerate is better than sandstone and mudstone；cyclic loading is better than step cyclic loading and monotonic loading；accumulated energy is better than AE and counts for identifying Kaiser effect point. The analysis of counts，power and frequency of AE events and the deformation and cracking micromechanism of rock samples under different load levels and cycles，suggesting that there are two types of AE events：one is frictional AE caused by the closure of original cracks and friction between the particles of rock；the other is cracking AE produced by the new failure extension or dislocation. Suppressing frictional AE and highlighting cracking AE can make Kaiser effect point more clear. It is recommended that the cyclic loading should be used to eliminate the frictional AE，and accumulated energy should be used to indentify Kaiser effect point，and the pre-loading stress level should exceed the estimated geostress.  

Generally，material parameters are assumed as constant in stability analysis of reservoir bank；it is inconsistent with the fact that material parameters would vary with change in saturation state as change in water level. The precision of calculation is limited；thus safety judgment of bank is influenced. Based on theory of unsaturated soil mechanics and principle of effective stress，not only material parameters are assumed as the function of saturation，but also the model of unsaturated liquid-solid coupling is introduced to numerical analysis of bank stability. Taking landslide No.1 at the bank of Xiaolangdi Reservoir for example，several works such as change in water level，rainfall，earthquake，etc. are carried out as well as the contrast of correlative results are worked out. Study shows that results of the model of unsaturated liquid-solid coupling are consistent with the fact basically；thus the model can be used to analyze the stability of reservoir bank. Moreover，material parameters defined as the function of saturation state，soak process of soil can be described better. Finally，relative to limit equilibrium method，not only constitute relation of stress and strain about material can be considered，but also results of seepage，stress，displacement，etc. can be achieved with the finite element method；thus it will be applicable to stability analysis of bank. The research results can be used as reference for safety evaluation and prevention and treatment of reservoir banks.

Now the assumed condition of common sampling window methods is that joint centers obey the uniform distribution，it means that the location of sampling windows has no effect on mean trace length of joints. Yet in fact，as products of the lengthy geological evolution，joints have been suffered from multiple geological formations and tectonic movements，shapes and scales have been changed largely；so their distributes display typical geological rhythm characteristics. If sampling windows are arranged at random，they will generate different mean trace length results. In order to find the relationship between mean trace length of joints and location of sampling window，taking the underground main powerhouse of Dagangshan hydropower station for example，firstly，the geological evolution rule of joints at its downstream wall was analyzed，and that diabase dikes and their influence areas were identified as the dominant joint sets，then choosing diabase dike ?81 and its influence areas to research their geological rhythm characteristics in detail；based on their characteristics，these proposals about the locations，sizes and estimation methods of sampling windows for deciding mean trace length of joints are put forward. Finally，five kinds of methods are used to calculate and compare the estimation results of mean trace length in different sections. The results indicate that the mean trace length of joints has a strong relationship with the location of sampling window；different distribution characters of joints and different locations of sampling windows will lead to different calculated values. So when using sampling window methods，it is needed to adequately consider the development rules of objective joints，and assign the location of sampling window accurately in order to contain all kinds of joints as far as possible；the sampling window should include intersecting，transecting and contained traces synchronously；and the estimation method should be chosen adequately.

Two large-scale model tests on 3×3 pile groups under lateral loading with different eccentricities(e = 6D and e = 11D，D is pile diameter) in saturated silt are conducted to investigate the law that the applied loads are transferred in the pile groups. The load-displacement curves of the pile groups indicated that an applied torque significantly decreases the lateral resistance of the pile groups. Both lateral and torsional resistances of the individual pile were simultaneously mobilized to resist the applied load. It is found that the lateral and torsional resistances，and in turn，the bending moments，of the individual pile are significantly different；and the difference becomes larger as the eccentricity increases. Both torsional and lateral resistances of the individual pile contribute to resist the applied torque；and the contribution of torsional resistances of the individual pile to the applied torque significantly decreases with the increase in applied load.

Using consolidation apparatus for unsaturated soils，the confined compression tests at constant water content are conducted on unsaturated undisturbed loess in Xi?an under different initial water contents. The maximum net normal stress is 1 600 kPa. Matric suction is measured by an elevated all round air pressure and with measured pore-water pressure under zero-applied stress and applied stress. Effects of stress state on matric suction characteristics of unsaturated undisturbed loess are determined and illustrated under confined compression condition. Experimental results show that the net normal stress change influences the matric suction state of unsaturated undisturbed loess at constant water content. The regularity of influence greatly depends on the initial water content of specimen. The degree of influence is related to the magnitude of applied stress and initial water content. The influence of small net normal stress(≤400 kPa) on matric suction of unsaturated undisturbed loess is slight under different initial water contents. The influence of stress where the initial water content of specimen is smaller than plastic limit is greater than that where the initial water content of specimen is higher than plastic limit. The relationship between matric suction and saturation degree related to applied stress is different from that related to water content. The influence of net normal stress on soil-water characteristic curve(SWCC) is related to magnitude of net normal stress. The effect of small net normal stress(≤400 kPa) on SWCC is much smaller than that of large net stress(＞400 kPa). When net normal stress is small(≤400 kPa)，the soil-water characteristics are illustrated by the relation between matric suction and gravimetric water content under zero-applied stress for the sake of convenient use in engineering；and when it is large(＞400 kPa)，they are illustrated respectively. The relation between matric suction and gravimetric water content can be illustrated by power function under different applied stresses.

Using self-developed model drilling rig and pile model test system，a new type of soil displacement screw(SDS) pile in homogeneous sand has been studied to explore the load transfer mechanism and load deformation behaviors of full displacement pile. The investigations show that the skin friction along SDS pile is asynchronous distribution，within the soil-pile relative displacement of 20% pile diameter，the skin friction of pile due to soil-pile relative displacement is monotonous increase；and the shaft resistance of pile is much higher than the base resistance. Comparison of test results between SDS piles and continuous flight auger(CFA) piles，the factor of pile length played a more active role on the bearing capacity and deformation behavior of SDS piles than those of CFA piles. Under same model test conditions of the length，diameter of piles and soil，the ultimate bearing capacities of SDS piles are about 25% to 70% higher than those of CFA piles. Based on Terzaghi and Peck?s theory of earth pressure and the stress path method as well，the main reasons are clarified about the difference of load deformation behavior resulted from disparate pile construction methods and installation effects which lead to change physical state and mechanical parameters of soil around SDS piles and CFA piles .

To study appropriateness of granitic residual soil used as fillings of high-speed railways foundation bed bottom and embankment，the clay mineral composition，fluid plasticity index，CBR value，relationship between cumulative residual strain and loading time and critical dynamic stress，etc. which are for its engineering properties，are firstly studied. According to codes for design of Chinese and Japanese high-speed railway，it shall be improved that granitic residual soil is not used directly as a high-speed railway subgrade filling. Secondly，according to the experience of improved fine-grained soil in Japan and China，and characteristics of granitic residual soil，it will be identified that cement contents are added extra in granitic residual soil used as fillings of high-speed railways foundation bed bottom and embankment. Thirdly，the comparison of the field test data between finite element analysis results of performance of improved granitic residual soil subgrade under cyclic loading is analyzed；the dynamic similarity analysis of performance of improved granitic residual soil subgrade is carried out；the parameters of cyclic loading test are identified for performance of highway. Finally，The dynamic performance and physico-mechanical characteristics of improved granitic residual soil used in subgrade of Wuhan—Guangzhou high-speed railways in Qingyuan region of Guangdong Province are also studied，relying on PMS–500 cyclic loading experimental equipment. The dynamic performance and deformation law of improved granitic residual soil subgrade are analyzed under different cyclic loading with and without soaking. It is shown that the improved granitic residual soil could meet the design requirements for all the dynamic indicators and residual settlement of high-speed railway subgrade being influenced by long-term cyclic loading with and without soaking，and could be used to fill the embankment and subgrade bed of highways．

By the field test，influences of immersion on the top of slope about earth pressure of unsaturated intact loess and displacement of free face of slope are studied. The results show that：(1) When the top of slope is soaked，the earth pressure strength increases rapidly；the maximum earth pressure strength of the soaked slope is 4 times of intact slope before the slope landslide. (2) After the slope landslide，shear outlet of landslide is at the one third of the slope height rather than the toe of slope. (3) Earth pressure strength of unsaturated intact loess is mainly produced by residual downslide thrust. (4) The displacement of free face of slope which is nonlinear relationship with earth pressure and the displacement of free face of slope is not caused by earth pressure. (5) In the process of water immersion，changing process of earth pressure can be divided into three stages：the first stage is changing stage of mechanical properties of slide earth body；the second stage is integral slippage stage of slide earth body；the third stage is integral deformation stage of slide earth body. (6) For the vertical cut slope of unsaturated intact loess，ultimate alarming value of the horizontal displacement is 10 mm；if the horizontal displacement of vertical cut slope is more than 10 mm，the slope would probably evolve into a landslide.