New understandings about the mechanism of rockburst of high stress tunnel are presented on the basis of rockburst model tests. Energy accumulated within the rock mass of rockburst alone is insufficient to generate ejective rockburst，extra energy must be transmitted from the surrounding rock to rockburst mass when rockburst happens. Energy convergence from surrounding rock to burst rock is a significant premise of ejective rockburst. In the process of ejective rockburst，the transformation from static to dynamic state is caused by the surplus energy released from the surrounding rock to rockburst body. Rockburst，even intense rockburst may happen when  = 0.3–0.7，because of the existence of regions with weak structures and stress concentrations in the surrounding rock. Ejective rockburst could not be realized in the existing model tests under the slow loading with the ordinary hydraulic control system of slow oil supply. New model test devices were thus developed. Test results show that the developed devices can simulate ejective rockburst phenomenon well.

Advanced geological prediction has been an essential part in tunnel construction and has played an important role in aspects of informative construction，disaster prevention and safety guarantee in tunneling engineering. The state of the art and the trends of advanced geological prediction in drilling and blasting tunneling and TBM tunneling are summarized according to the available data. Great progress has been made in the advanced geological prediction in drilling and blasting tunneling with the emergence of a set of special methods，technologies and equipments，such as the reflection seismic method，the electromagnetic method and the electrical resistivity method，which gradually led to achieve quantitative detection and form a method of comprehensive advanced geological prediction. The comprehensive advanced geological prediction based on the fusion of multiple geophysical information and the method of combined inversion was considered an appropriate way for suppressing the multiple solutions and enhancing the reliability of advanced prediction. The methods of induced polarization and nuclear magnetic resonance have shown great prospects in the quantitative detection of water because of the sensitivity response of its parameters. Due to the particularity and complexity in the environment of TBM tunnel construction，some special detecting technologies did not meet the requirements of engineering practice which are at the preliminary stage of study and there have been no reliable and effective technologies for advanced prediction available generally. The latest developments in our group regarding three kinds of advanced prediction technology in drilling and blasting tunneling and its applicability to TBM tunnelling were described here. A system of comprehensive advanced geological prediction with four stages was proposed based on the theory of constrained joint inversion. The future studies are considered to be in the following four directions：(1) the further development of comprehensive quantitative detection during tunnel construction；(2) the technologies and equipments of advanced geological prediction in TBM tunnelling；(3) the theory and technology of precision probing at drilling；(4) the real time advanced prediction and construction disaster monitoring.

Brittleness is one of the most important properties for rock materials，to which many mechanical behaviors of rock are related. Existing indices of brittleness based on strength，stress-strain curve，loading and unloading tests，hardness and mineral composition were summarized，and merits and weakness of the indices were analyzed in detail. In order to evaluate the brittleness of rocks reasonably and accurately，a new index of brittleness reflecting the characteristic of plastic yielding and the effect of stress state was introduced on basis of the relative magnitude and the absolute velocity of post peak stress dropping. Axial and triaxial compression tests were conducted to examine the new index. The results of tests show that brittleness of cement mortar and marble both decrease with the increasing of confining pressure and the brittleness of marble is greater than the one of cement mortar under the same stress state，which agree with the actual brittleness of the two rock materials. Brittleness of limestone，marble，granite and red sandstone decrease in order and their axial strain at failure increase in order gradually，which conforms to that the low values of elongation means more brittle. The test results verified the reliability of the new index of brittleness nicely which may enrich and improve the existing evaluation methods of rock brittleness.

Theoretical solution of fracturing of hard roof has not been well solved in rock mechanics. A strata of unit width along middle axis of stope was considered to study the influence of cracks on the internal forces，deflections and strain energy of hard roof. The coal seam and the immediate roof in front of coal wall were considered to be elastic. The load above roof was assumed to be invariable during the initial stage of cracking. The maximum strain was used as a criterion of crack occurrence. Expressions for bending moment，shear force and deflection of hard roof at its initial stage of cracking due to periodic pressure were derived satisfying the conditions of continuity，natural boundaries and boundaries of crack surfaces. Numerical examples computed with Matlab were presented. Section of crack initiation was in front of coal wall. The settlements of the roof behind the cracked surface and gob were increased remarkably with the development of cracks. The deflection of the roof in front of the cracked surface rebounded，which agreed with the characteristics of the monitored field results. The values of bending moments and shear forces behind coal wall were invariant. While，the bending moment and strain energy in front of coal wall decreased because of crack initiation. The shear forces in front of the crack surface decreased，and fluctuated near the crack surface. The position 15 m ahead of coal wall is an area of concentrated strain energy released from the hard roof and crack occurring. The internal force and strain energy in front of coal wall decreased which was beneficial safety-wise.

The uniaxial compression with stepped relaxation was conducted on coal samples with the testing system of rock mechanics RMT–150B. The aging characteristics of deformation，strength and failure of coal samples under uniaxial compression and uniaxial compression with stepped relaxation were analyzed. The results show that the stress-strain curves ahead of the peak values of coal samples at two loading conditions have four conventional stages，i.e. densification，elastic，yielding and failure. The stress-strain curves of uniaxial compression with stepped relaxations have a local drop of stress during the relaxation. The values of mechanical parameters of uniaxial compression are higher than ones of that with stepped relaxation，showing that the mechanical parameters of coal samples have aging characteristics. When the ratio of stress relaxation is lower than 70%，the characteristics of stress relaxation is not obvious. When the ratio of stress relaxation is higher than 70%，materials of lower strengths were gradually damaged by the energy stored in the materials of higher strength inside coal samples and the materials of higher strength carried higher stresses and were also be damaged gradually. The higher the ratio of the stress relaxation was，the shorter the length of time of failure was. There were noticeable surfaces of tension-shear fracturing for failure samples under uniaxial compression；but the failure cracks of coal samples in the stepped relaxation tests were in loading directions and many chippings and fragments were formed，showing clearly a characteristic of lateral expansion.

The stress effect on friction angles of structural planes of rocks was considered. In order to obtain the relationship between peak friction angle and normal stress，modeling materials for rock similar to calcareous slate in physico-mechanical properties were obtained through studying the ratios of raw materials such as the medium sand，the cement，the silica powder，the naphthalene super-plasticizer of non-air entraining. Ten groups of rock structural planes with different waviness and roughness were made. Friction angles of the rock structural planes under different normal stresses were determined with the direct shear apparatus. Results show that the peak friction angle and its rate of variation of rock joints are decreased with the increasing of normal stress instead of a constant value generally considered. The residual friction angles of structural planes changed little with the increasing of normal stresses. The peak friction angles under the same normal stress are different for each rock model due to the differences of surface waviness and roughness of structural planes. The stress effect on peak friction angles of rock joints are the same with the variation of friction angles determined with the failure criterion of joint roughness coefficient-joint wall compressive strength(JRC-JCS)，the larger the JRC is，the more significant the stress effect on peak friction angle is.

The digital images of the surface of jointed gypsum samples under uniaxial compression were analyzed in order to study the damage evolution of jointed rock mass quantitatively. A computing program was developed with Matlab for the identification of individual crack and the calculations of the length and orientation of cracks，the fractions of total crack area and the total fractal dimensions of cracks. The results of the digital images considering the inclination angles and continuity rates of joints were analyzed. Both the fractions of total crack area and the total fractal dimensions of cracks increased with the increasing of axial strain in similar tendency. The specimens were classified into two groups according to the orientation angles of joints. The specimens with angles of 0°，15°，75°and 90°were assigned in the first group(the main failure mode is axial splitting)，and the ones with angles of 30°，45°and 60°in the second group(the main failure mode is shear sliding). The fractions of total crack area and the total fractal dimensions of cracks of the first group are larger than those of the second group. When the continuity factors of joints were the same，the fractions of total crack area of the specimens with different orientation angles of joint were largely the same at the beginning of tests；while the curves of the fractions of total crack area vs. the orientation angles of joint were V-shaped at the peak load and at the end of test (the maximum and the minimum values were for specimens with the orientation angles of joint of 0°and 45°respectively). The anisotropic characteristic of surface cracks of the jointed specimens at the beginning of test or during the loading can be represented by the distribution of fractions of crack area along the crack orientations. The study showed that the anisotropic damage evolution of jointed specimens was efficiently captured with the method of image analysis.

An elastoplastic constitutive model considering static liquefaction of tailings sand was proposed in the framework of critical state soil mechanics. The constitutive model was embedded into the software FLAC to simulate the static liquefaction phenomena of tailings pond. The predicted results from the numerical simulation of undrained triaxial tests using the proposed model have a good agreement with the experimental data of samples of sand-silt mixtures，which proved the capability of the model to describe the mechanical response of tailings sand. A typical case of liquefaction of tailings dams were chosen to validate the proposed model. The simulated results of the case show that the static liquefaction can happen in certain areas of the pond and serious failure of flowing sliding may occur with the rising of pore water pressure under the condition of high depositing rate.

There are certain limitations in the current theory of rockburst supporting based on static rock mechanics. The dynamical mechanism of rockburst caused by the external disturbance and the surrounding rock itself was discussed from the perspective of structural effect of surrounding rock. The external disturbance may easily lead to the damage of the elastic rock zone adjacent to the broken rock zone because of the reflection wave of stresses. Rockburst can be regarded as the adjustment process of self-sustained time-varying structure of surrounding rock under certain conditions. A principle of controlling the time-varying the structure in supporting was put forward. With the present supporting measures，the surface rocks of underground cavern would spall and peel and the bolt pallets would hang in the air after the happening of rockbursts. A static-dynamic combined supporting method to control the rockburst disaster was put forward with the key techniques of anchoring reservation and static-dynamic combined bolts. The extensible components of bolts should be installed in the vicinity of the elastic rock zone and in the broken rock zone；so that enough spaces may be provided for the dilatancy and deformation of rocks in elastic zone damaged by the reflected stress waves. Meanwhile，the tail of the anchoring rod can strengthen the broken zone rock. The preliminary application to a deep rockburst roadway，it is proved that the new technology of supporting is effective in the prevention of rockburst.

Coupled thermo-hydro-mechanical(THM) fracturing tests and scanning electron microscope(SEM) tests were performed to study the macroscopic and microscopic characteristics of coupled THM fracturing of brittle rocks. Finite element method and a new fracture criterion on the ratios of stress intensity factor were applied to predict the fracturing mode under THM coupled condition. The red sandstone specimens are found to have three types of modes of fracturing macroscopically with the corresponding fracturing features microscopically under different THM coupling conditions. Transverse fracturing occurs macroscopically and transgranular shear fractures occur microscopically for the specimens under low temperature，low hydraulic pressure and high confining pressure. Longitudinal fracturing occurs macroscopically and intergranular tensile fractures occur microscopically for the specimens under high temperature，high hydraulic pressure and low confining pressure. Cross directional(transverse and longitudinal) fracturing occurs macroscopically and mixed fractures(transgranular and intergranular) occur in the specimens under medium temperature，medium hydraulic pressure and medium confining pressure. The predicted modes of fracturing under THM coupling with the finite element method and the new fracture criterion of ratios of stress intensity factor are found to be in good agreements with that obtained with the fractographic analysis.

A simplified expression under conventional three axis test conditions is presented after reviewing the constitutive relation of Drucker-Prager material with the parameters changing with internal variables. The axial plastic strains were selected as the internal variables and the relations between the increments of internal variables and the ones of external variables of strains and stresses were obtained. The values of internal variables at each point of recording in testing were thus obtained. In order to determine the values of two strength parameters corresponding to the same internal variable through a number of tests，the stresses of each test were interpolated among uniformly distributed values of internal variables；so that the strength parameters for a given internal  variable can be derived from the yield surface equation. As such the variations of the strength parameters with the internal variables were obtained without the need of assuming one beforehand. Results of tests show that the variations of two strength parameters are not the same and the values of internal variables at peak stresses are different under different confining pressures，which agrees with the viewpoint of others that confining pressure can improve the ultimate strength and delay its coming.

Numerical simulations of initial dynamic extension of microcracks of mode I under shock wave loading of blasting using ABAQUS embedded with a numerical module of dummy nodes and a load subroutine of air wedge was carried out to investigate the blasting-enhanced permeability of low-permeability sandstone with uranium deposits(BEPUD) . The numerical results indicated that the longer duration of rise time of shock waves，the more microcracks were activated in rocks. High peak pressure of shock wave led to high release rate of dynamic energy at crack tips. The excessive or insufficient peak pressures of shock wave were not conducive for the initial dynamic extension of microcracks and fully consumption of explosive energy. In virtue of the comparison of results from the static and the dynamic numerical analysis under explosive gas load，more crack growth in the dynamic analysis was found than in quasi-static analysis. The dynamic analysis explained better the phenomenon of the movement of crack instability.

The process of acoustic emission(AE) of Himalayan salt rock under high temperature and uniaxial loading conditions was investigated using the material test system MTS 810 and the acoustic emission detector AE21C. The characteristics of AE of salt rock at temperatures between 20 ℃ and 600 ℃ and at different loading stages after the high temperature were analyzed. The rate of AE of the salt rock when the temperature was between 50 ℃–400 ℃ was lower than that at 50 ℃；while the AE activity of salt rock in heating process became more frequently with the temperature rising if temperature was over 400 ℃. In the loading process，the frequency and the intensity of AE of the salt rock were increased with the rise of temperature when the temperatures were between 20 ℃–150 ℃，and the rate of AE of the salt rock was reduced with increasing temperature between 170 ℃–600 ℃. The temperature range of self-healing for salt rock is 170 ℃–400 ℃. The activity of AE of salt rock at high temperature is weaker than that after the high temperature though the temperature degree is the same.

In order to quantitatively analyze the intensity and variation of airblast generated by the movement of sliding mass，a rapid and long-runout landslide at Niujuangou was studied with a computational fluid dynamics(CFD) software incorporating the resistance along the movement path defined by the law of Voellmy. The numerical results revealed that the whole travelling process of sliding mass lasted about 112 s and the maximum speed at every moment appeared in the front zone of sliding mass with two peak values of 52 m/s at 9 s and 44 m/s at 49 s respectively. The maximum velocity of airblast of 45 m/s appeared at 9 s and the maximum pressure of airblast was 625 Pa，equivalent to a violent storm，and was generated at the moment when the sliding of mass was just initiated. The greatest squeezing effect of the sliding mass to the air ahead occurred when the sliding mass was in rigid motion. As the sliding mass fragmented，the airblast pressure in front of the sliding mass decreased with the reducing of the height of the front head of the slide slope. The farther away from the front of sliding mass，the lower the pressure was. The rugged path of sliding had a large influence on the distributions and magnitudes of the pressures of airblast. When the front of sliding mass arrived at the toe of a convex slope，positive pressures with large variation of gradient will be induced at windward side，and negative pressures was induced at leeward side. When the sliding mass bursts out the scarp，it violently squeezed the air ahead leading to a sharp increase of positive pressures.

Scanning experiments under uniaxial loading for coal samples were carried out using the industrial computerized tomography(CT) experiment system based on the principle of stereology. The curves were obtained by calculating the sum of squared eigenvalues of crack tensor with different threshold values for CT images. The inflection point of the curve was taken as the threshold which was verified to be the best threshold value for calculation of the second order tensors. The binary image line and the eigenvalues of regional parameters by the binary stereological image were obtained. The sum of squared eigenvalues was proposed as the parameter of coal specimen damaging. Three orthogonal surfaces of fractures of the reconstructed three-dimensional coal specimen were selected to calculate the relationship between the squared eigenvalues of second order tensor and the porosity，which could provide a reference for describing crack damage in three dimensions.

A series of conventional triaxial tests with uniaxial preloading and triaxial tests with the confining pressure reducing were carried out on rhyolite specimens with natural micro fissures as the base of research on tardy failure of fissured surrounding rock of tunnel under the disturbance of excavation. Stress-strain curves of specimens with different micro fissures on two kinds of stress paths were obtained. The natural rhyolite specimens with micro fissures were found all to be remarkable brittle without a conspicuous yielding phase. The characteristics and distribution direction of micro fissures greatly affected the mechanical properties of specimens under two different stress paths. The micro fissures perpendicular to the maximum principal stress were difficult to extend leading to shear destruction and better mechanical behaviour. While if the initial dominating angle was small and the micro fissures linked dendritically with each other，macro tensile cracks would be formed in specimens，which weaken the mechanical behaviour of rocks. When the initial dominating angle of specimens with natural micro fissures was 46°in conventional triaxial tests，the mechanical properties were the worst. The lateral micro fissures were closed under uniaxial preloading. The strength，the elastic modulus and the deformation modulus of specimens measured with the conventional triaxial tests under pre-loading were increased due to the closing of fissures，Poisson?s ratios were basically unchanged and the characteristic of brittleness was more conspicuous.

In order to evaluate the cavability of ore-rocks in block caving method，fuzzy mathematics and matter element analysis method were combined together. The cavability of ore-rocks was divided into five grades including none，poor，fair，good and perfect as the types of matters elements. The RQD，the saturated uniaxial compressive strength，the distance of joint，the hydraulic radius of first cut and the hydraulic feature values were taken as the indices of evaluation. Based on the principle of membership degree in fuzzy evaluation analysis，the membership degree of ore-rock index relative to different evaluation categories were calculated. A model of cavability of ore-rocks in terms of complex fuzzy matter element analysis was established；and a method of cavabiltiy description was presented. The cavability of ore-rocks in a copper-molybdenum mine at the Jiuding mountain was evaluated with the proposed method. The results indicate that：the cavability of altered hornfels is fair；the cavability of altered granite porphyry is good；and the cavability of dense granite porphyry is poor. The results of the evaluation agree well with results of ore lumpiness monitoring and avoided the problem of incompatibility of the evaluation with a single factor index.

Collision and slide between blocks are related to friction，while the original three-dimensional combined finite-discrete element method(FEM/DEM) did not consider the effect of friction. The FEM/DEM based on the potential associated with contact force was therefore discussed in detail. The potential was found to characterize the stored energy due to embedding and contacts；namely，the greater the potential，the greater the embedding and the energy stored in the contact. The classic Coulomb friction was then taken into account in the original three-dimensional FEM/DEM. An example of slider-on-ramp having an analytical solution and an example of bridge collapsing were analysed，which verified the correctness of implementation of Coulomb friction. The results show that the numerical solution of the example of bevel slider is in good agreement with the analytical solution and the improved FEM/DEM is capable of solving complex engineering problems.

The difficulties of pumped vacuum pressure to reach the deep soil and the severe clogging of drainage board in the current method of vacuum preloading lead to unsatisfactory effect in soil reinforcement and are unable to meet the needs of engineering applications. The vacuum preloading technology for the treatment dredged ground with anti-clogging measures was thus proposed. The anti-clogging drainage boards used the filtering membranes of hydrophilic material without concave and convex structures. The membrane and core material were rolled and bonded together to improve the effect of draining. Moreover，the vacuum tubes connected with the PVDs directly and airtightly formed a closed anti-clogging drainage system. As a result，the flow path of vacuum was shortened，the loss of the degree of vacuum along the path was reduced；the vacuum pressure reached the deeper soil layers，the dissipation of pore pressure in soil was accelerated and the effect of soil consolidation was improved. Field and laboratory model tests on the vacuum preloading with and without anti-clogging were carried out；and then the comparison of the experimental results confirmed the effectiveness of the new measures.

The actual development of shear strengths of soft soils in the thick hydraulic reclaimed foundations improved by the technology of pumped vacuuming combined with heaped preloading was qualitatively analyzed in terms of the principle of effective stresses and the method of stress paths. The development of soil shear strength under the groundwater level was found to be different from that of above the groundwater level. An analytical solution for soil shear strengths considering the effect of groundwater levels was therefore derived based on the theory of the uniqueness of effective stresses. The increments of soil shear strength at different depths after the dissipation of the excess pore water pressure under constant load in an area at Gaolan，Zhuhai seaport were calculated with the derived analytical solution. Comparisons with the results from the unconfined compression test and triaxial compression test revealed that the averaged error between the calculated and measured values is only 8.0% in terms of the undrained shear strength and is only 3.2% in terms of the shear strength in soil failure surface. Therefore，the calculated results based on the analytical solution agree well with the measured results.

To illustrate the factors controlling the strength development of calcium carbide residue(CCR) and quicklime stabilized over-wet clay soils，a series of laboratory tests including unconfined compression，soil pH measuring，mercury intrusion porosimetry(MIP) and thermo gravimetric analysis(TGA) were conducted to quantify the relationships between the unconfined compressive strength with the soil pH，the pore size distribution and the content of pozzolanic reaction product. The experimental results show that the strengths of CCR are similar to ones of quicklime stabilized soils at early stage and are 1.05 to 1.16 times higher at late stage. The fractions of clay particles，the specific surface area(SSA)，and the contents of reactive silica(Si) and alumina(Al) of CCR rebound are 1.72，5 and 1.71 times those of quicklime respectively. The pH values of the CCR stabilized soil are approximately 12.4 to 12.6 with the curing times of 28 to 120 days，which is in favor of the pozzolanic reactions between the CCR and soil particles. In addition，the pozzolanic reaction products in CCR stabilized soil are 1.06 and 1.10 times that of the quicklime stabilized soil. The sum of volumes of micro(＜0.007 μm) and small (0.007–0.900 μm) pores of the CCR stabilized soil are 1.05 and 1.23 times that of the quicklime stabilized soil when the curing times are 28 and 120 days.

Temperature distribution in the roadbed and neighboring soil of high-speed railway(HSR) in seasonally frozen regions has significant influence on the stability of roadbed. The temperature distributions at the toe of slope，a short distance away from the road and at different locations in the roadbed were analyzed based on the results of three years monitoring and the atmospheric temperature data at Shuangcheng district from Harbin-Dalian HSR. Formulae of temperature estimation of different locations and depths were established in terms of the temperature amplitudes and average values. A mathematical model of the unsteady phase transition of geothermal field was presented to analyze the temporal and spatial characteristics of temperatures and to predict the trends of variation of geothermal field. Monitored data and calculated results both indicated that the temperature distributions were related to the soil compositions，the thermal coefficients of diffusion，the climate and the locations，etc. The roadbed of HSR of seasonally frozen regions eventually formed a relatively stable layer of seasonal frozen with a stable temperature and asymmetric geothermal field. The difference of geothermal field of shady and sunny slopes at two sides of embankment exists and may lead to the uneven settlements transversely and longitudinally which may affect the stability of roadbed.