Focusing on the development process of rockbursts，new development of key aspects is addressed in this paper. First of all，elaborations were made on rockburst types，intensitiesy gradations，typical features induced by the tunnel boring machine(TBM) or the drilling and blasting(D&B) excavation methods，and characteristics in different rock lithology. Then，various technical means for investigating rockburst development process were analyzed，such as the laboratory block scale experiments，physcial model tests，numerical simulation，comprehensive in situ inspection and field monitoring. The development mechanisms of different rockburst types and the microseismcity evolution laws ofin rockbursts development process induced by different excavation methods were thus revealed. Afterward，the rockburst assessmentestimation methods and the quantitative warning methods of rockburst location and intensity based on the in situ microseismicity data were discussed based on the in situ microseismicity data. Moreover，dynamic prevention and controlling techniques were presented for different rockburst types induced by different excavation methods including the optimized excavation design method，optimized stress release design method，optimized energy-absorption support design method and the dynamic control methods. Furthermore，a case study was presented with detail information on rockburst monitoring warning，dynamic control and the applicability of introducing methods. Finally，the future trends on rockburst development process were discussed.

The artificial freezing method has been widely used in excavation of water-rich soft rock layers，and hence，understanding the mechanical properties of frozen rock is of great engineering significance. Taking saturated cretaceous sandstone as testing sample，triaxial compression tests with different confining pressures(0，2，4 and 6 MPa) were carried out at different temperatures(+20 ℃，0 ℃，－10 ℃ and －20 ℃). The results demonstrate a strong negative correlation between the strength of saturated sandstone and the subzero temperature. Under the same confining pressure, the peak pressure increases by 2–4 times when the temperature reduces from +20 ℃ to －20 ℃. At a constant freezing temperature，the peak strength increases by 1–3 times when the confining pressure increases from 0 MPa to 6 MPa. Both the cohesive force and the internal friction angle rise with decreasing the temperature，up to 5 times for the former. A strength forecasting model for frozen sandstone is proposed based on the comparison of prediction accuracy of five existing strength criterion theories according to the test results. The Rocker criterion is proven to be optimal and further modified taking into account the effect of the temperature on its parameters. The above results could provide a guidance for rock excavation both in cold regions and artificial frozen layers.

The measured data of the engineering seismic effects induced by underground nuclear explosion were systematically analyzed，and a consistent method for quantitatively representing deformation characteristics with a dimensionless characteristic energy factor was constructed by analyzing the energy radiation characteristics of deep buried nuclear explosion，shallow buried explosion and surface explosion. The threshold value and the gradation decline law of the irreversible deformation energy factor in the range of near area to middle/far area of the explosion were obtained. A theoretical method for calculating the local irreversible deformation of the engineering seismic effects at a certain ratio distance away from the center caused by the underground nuclear explosion was proposed for the first time，and the scientific reliability of the method was verified by the measured data. Based on the in-depth study of the influence of the explosion-activated rock block deformation on the surrounding rock stability of underground engineering，it was pointed out that the design of deep-ground protection engineering resisting large yield earth-penetrating weapons must pay attention to the engineering seismic effect，and its calculation method was given.

Deep mining is an inevitable way for the future development of hard rock mines. Rockburst disaster in deep mining is one of the key scientific problems that must be solved in the future development of hard rock mines. Since clearly interpreting the rockburst mechanism is being a worldwide scientific difficulty，it is necessary to conduct accurate and reliable analyses of the energy storage ability of deep surrounding rock，the high stress environment and the whole path of excavation stress state. It was fonud that rockburst essentially belongs to the coupled static-dynamic loading problem of hard rock medium subjected to "static stress + dynamic disturbance". According to this idea and on the basis of extensive collection of typical rockburst cases all over the world，some necessary conditions for rockburst，i.e. intact elastic-brittle rock mass，high geostress and dynamic disturbance，were analyzed，and the coupled static-dynamic loading mechanical mechanism of rockburst and its recent research progress were systematically summarized. Especially，by using hard rock material，the mechanical mechanism of rockburst was studied from two aspects of "static stress + unloading disturbance" and "static stress + loading disturbance" on one hand，and on the other hand，considering the spatial structure effect of deep excavation，the failure characteristics of strain rockburst in surrounding rock of deep circular cavern wall were investigated from two aspects of "static stress + stress adjustment" and "static stress + dynamic disturbance". The different types of coupled static-dynamic loading mechanism of rockburst were further clarified. In addition，a dynamic criterion referring to dynamic-static energy indices for rockburst occurrence and the methods for controlling rockburst occurrence in deep hard rock mining were proposed. The combined effects of coupled static and dynamic loading/unloading for inducing rockburst can provide a new idea and method for explaining rockburst mechanism.

In order to study the precursory characteristics of acoustic emission before the peak strength and the acoustic emission characteristics of the loading-unloading process for guiding the application of AE technology in rock mass engineering monitoring and disaster warning, six kinds of rocks including granodiorite，hornfels，skarn，copper ore，wolfram-molybdenum ore and lead-zinc ore were tested respectively under uniaxial compression，incremental cyclic loading-unloading and incremental isobaric cyclic loading-unloading，and the relative tranquil period of acoustic emission before the peak strength，the AE characteristics of unloading process，the Felicity ratio under two different cyclic loading-unloading modes and changes of the load-unload response ratio were studied. The results show that some rocks always present the“relatively tranquil period”phenomenon under three different loading modes. The low frequency components of the AE events of a variety of rock samples increase significantly before failure，and the closer to the failure, the more the large amplitudes AE events. Under two different cyclic loading and unloading ways，Felicity effect occurs with Kaiser effect disappearing when the stress level reaches 50% to 60% of the peak intensity. Both Felicity ratio and load-unload response ratio are greater than 1 in the low stress level and fluctuate around 1 in the middle stress level. In the high stress level stage，the internal cracks of the rocks expand unstably with the Felicity ratio reducing and the load-unload response ratio increasing，and the samples destroy when the Felicity ratio reduces to 0.64–0.89. The Felicity ratio and the load-unload response ratio of the relatively tranquil period may be used as the parameters of rock failure prediction.

In order to study the precursory characteristics of acoustic emission before the peak strength and the acoustic emission characteristics of the loading-unloading process for guiding the application of AE technology in rock mass engineering monitoring and disaster warning, six kinds of rocks including granodiorite，hornfels，skarn，copper ore，wolfram-molybdenum ore and lead-zinc ore were tested respectively under uniaxial compression，incremental cyclic loading-unloading and incremental isobaric cyclic loading-unloading，and the relative tranquil period of acoustic emission before the peak strength，the AE characteristics of unloading process，the Felicity ratio under two different cyclic loading-unloading modes and changes of the load-unload response ratio were studied. The results show that some rocks always present the“relatively tranquil period”phenomenon under three different loading modes. The low frequency components of the AE events of a variety of rock samples increase significantly before failure，and the closer to the failure, the more the large amplitudes AE events. Under two different cyclic loading and unloading ways，Felicity effect occurs with Kaiser effect disappearing when the stress level reaches 50% to 60% of the peak intensity. Both Felicity ratio and load-unload response ratio are greater than 1 in the low stress level and fluctuate around 1 in the middle stress level. In the high stress level stage，the internal cracks of the rocks expand unstably with the Felicity ratio reducing and the load-unload response ratio increasing，and the samples destroy when the Felicity ratio reduces to 0.64–0.89. The Felicity ratio and the load-unload response ratio of the relatively tranquil period may be used as the parameters of rock failure prediction.

Excavation of tunnels under deep high stress environment will induce unloading damage or even cracking of surrounding rock and，then，the damaged surrounding rock will rupture or fail under static and dynamic loads caused by mining activities. Therefore，it is necessary to study the dynamic and static mechanical behavior of damaged surrounding rock. Pre-peak unloading tests on 72 damaged marble specimens were performed under three confining pressures of 15，25 and 35 MPa with four unloading points respectively corresponding to 70%，80%，90% and 100% of each confining pressure，and then，static and dynamic uniaxial compression tests of the damaged samples were respectively carried out by MTS815 and split Hopkinson pressure bar(SHPB) test system. The test results show that the damage variable of the rock samples increases with increasing the unloading point/confining pressure under the same confining pressure/unloading point. The static and dynamic compressive strength and elastic modulus of the unloading damaged rock samples decrease with the damage variable in a negative exponential function. When the damage variable is lower than the critical value Dc = 0.17，the dynamic enhancement factor keeps stable around 1.5. The dynamic elastic modulus decreases rapidly while the static elastic modulus does not change significantly. When the damage variable is greater than 0.17，the dynamic enhancement factor increases sharply while the dynamic and static elastic moduli tend to be the same. The dynamic and static differences are attributed to the complex coupling of unloading damage effect and strain rate effect. The findings of this research can provide a reference for the selection of the mechanical parameters of the surrounding rock and the optimization of the support scheme.

The impact tendency of coal is a key factor triggering mine impact disasters，and the anisotropy of the impact tendency is resulted from weak structural planes such as beddings. In order to explore the influence of coal bedding on the impact tendency，three groups of standard coal samples collected from Tashan #4 coal seam were processed according to different bedding angles. The wave velocities and the mechanical parameters of the coal samples were respectively measured by the ZBL-U510 non-metal ultrasonic detector and the MTS815.04 rock servo stiffness test system，and the fracture characteristics of the coal samples were analyzed by scanning electron microscopy(SEM). The results show that Tashan #4 coal seam has typical hard coal characteristics and that every mechanical index shows strong anisotropy. The impact tendency of the samples is strongest at 90°of the bedding angle，followed by 0° and weakest at 45°. The stress-strain curves of the coal samples were summarized into three typical forms and the failure modes of the coal samples with different bedding angles were compared and analyzed. Based on the bearing characteristics and the difference of macro damage modes of the coal samples with different bedding angles，the failure modes for the impact tendency ranging from strong to weak are，in turn，sudden instability，progressive instability and ductile instability. The impact tendency of the coal samples with different bedding angles was analyzed from the point of the amount and the speed of energy accumulation and release. The fracture morphology of the coal samples with different bedding angles is different under scanning electron microscopy. The fracture morphologies at 90°，45° and 0° of the bedding angles are respectively smooth columnar，rough and breaking wave with more particles and smooth step. The samples have transgranular and intergranular fracture modes with different energy absorption and fracture speeds，which result in the mesoscopic difference of the impact tendency of the samples.

To investigate the inoculation mechanism of rockbursts in extra-long and deep-lying tunnels in Yarlung Zangbo suture zone and to reveal spatial and temporal distribution，failure characteristics and influencing factors of rockbursts，rockburst characters and inoculation effect. The newly built Sangzhuling and Bayu Tunnels in the project of Sichuan-Tibet railway，which locate at the Yarlung Zangbo suture(YZS)，were studied. Based on geological survey，field test，3D finite inversion of in-situ stress and statistical analysis on the rockburst records observed during the construction process，the forming reason，characteristics and influence of high geotemperature and high in-situ stress conditions were studied and the effects of high in-situ stress and high geotemperature on rockbursts in tunnels were analyzed combined with thermodynamic coupling calculation. The results show that，under the control of the special geotectonics and cenozoic magmatic activities in the YZS，the deep-lying and extra-long tunnels in the area present high in-situ stress and high geothermal characteristics. The three-dimensional inversion of in-situ stress indicates that，due to the marked influence of the tunnel depth and horizontal geological structure，the maximum horizontal principal stress and self-heavy stress at the axis of the Sangzhuling tunnel are respectively 1.44 and 0.78 times of those in the Bayu tunnel. The spatial distribution of rockbursts controlled by the vertical stress mainly concentrated in the vault and the face of the tunnel，while the rockbursts influenced by the horizontal stress occur mainly near Yarlung Zangbo River valley. Field experiments show that the rockburst of igneous rocks has a weak of medium tendency and that the difference of the rockburst tendency due to different lithologies in two tunnels is not obvious. Under the influence of the terrestrial heat flow and the depth of partial magmatic melt，the characteristics of high geotemperature of two tunnels vary from each other greatly. Calculations using thermo-mechanical coupling model show that the coupled thermal-mechanical effect in the excavation process of Sangzhuling tunnel is obvious under the influence of high geotemperature and the rockbursts in Bayu tunnel are mainly affected by the high in-situ stress.

To investigate the dynamic properties of sandstone under high temperature，impact compression tests at 6 loading rates were carried out under different temperatures of 25 ℃，200 ℃，400 ℃，600 ℃，800 ℃ and       1 000 ℃ using variable cross-section split Hopkinson pressure bar test apparatus and high temperature equipment. Test results show that there shows a positive quadratic function relationship between the dynamic peak stress and the loading rate. Strengthen effect of the temperature on the dynamic peak stress appears in the range of 200 ℃ to 800 ℃，which is most obvious at 200 ℃，while the dynamic peak stress is weaken at 1 000 ℃. There is also a positive quadratic function relationship between the dynamic peak strain and the loading rate. The effect of the temperature on the dynamic peak strain is inconspicuous from 200 ℃ to 600 ℃，but is remarkable at 800 ℃，especially at 1 000 ℃. The dynamic elastic modulus decreases with rising the temperature but is almost independent of the loading rate. The dynamic elastic modulus varies in a certain range from 200 ℃ to 600 ℃，while has a smaller change at 800 ℃ and 1 000 ℃. With increasing temperature，the failure mode presents a transformation from brittle failure to ductile-brittle failure. The bigger the loading rate is，the more the fracture surfaces are，the worse the broken degree is，and the smaller the fracture fragments are. At 1 000 ℃，fracture      effect is more remarkable in a larger loading rate.

According to the characteristics of rockfall protective nets，a set of flexible protective net system was proposed and developed for tunnel rockburst prevention，and the dynamic characteristics of the system and the performance of the components were studied. Based on rockburst investigations and field test results，a numerical analysis model of ejection rockbursts was established，and the ejection velocities of rocks under different initial stress conditions were obtained. According to the characteristics of rockbursts in Micangshan tunnel，the design prototype of the rockburst protective net was constructed and the numerical analysis model was established. The process of rock impacting the protective net was calculated numerically with different sizes and velocities，and the nonlinear dynamic responses were obtained. Comparisons between the results of numerical calculation and material test of protective net components were performed and the safety performance of the rockburst flexible protective net was evaluated. The research results show that the ejection velocity of rocks increases with increasing the initial stress，that the wire rope net is the main energy absorbing component of the protective system and that the wire rope net and bolts are the main bearing capacity components of the protective system. The flexible protective net system can effectively withstand the ejection rocks resulted from slight or moderate rockburst.

In order to study the breakage and energy release regularity of impact tendency roofs，physical similar material simulation experiment was carried out，and the distribution characteristics of microseismic events under the solid coal and the goaf and the relationship between microseismic events and the rock pressure were studied combined with microseismic monitoring instruments and pressure sensors. The influence of the rock pressure on energy accumulation and release of coal and rock mass was analyzed，and the mechanism of rockbursts induced by breakage of the key strata was revealed. The results show that the microseismic events under the solid coal mainly occur in the roof strata in front of the working face and that the energy release value of microseismic events under the solid coal is higher than that under the goaf. The microseismic events under the goaf mainly occur in the roof strata behind the working face，and the frequency of the microseismic events is higher than that under the solid coal. Based on the similarity theorem，the formula of the energy similarity ratio was deduced，and the energy value of large events in the physical similar material model was defined as 333.33 J. It was found that large events mostly occur near the inverted trapezoidal structure in the stress increasing area. With shortening the distance between the working face and the open-cut roadway，the period of energy accumulation and release of microseismic events decreases. When rockburst is induced by breakage of the key stratum，the elastic energy accumulated in the main key stratum provides energy for rockburst. The location of rockburst is generally in the stress increasing area affected by mining. The control strategies of controlling source，reducing stress concentration and conduction efficiency were put forward. The engineering monitoring results show that the roof of the working face is effectively controlled and safety production is guaranteed.

To investigate mechanical properties and strength parameters of gray sandstone in complex stress state，direct shear test，conventional triaxial compression test and hollow cylindrical triaxial compression test(coupled inner and outer confining pressures) were carried out by the conventional rock mechanics test equipment and self-developed hollow cylinder torsional apparatus for rock. By comparing the test results of conventional and hollow cylindrical triaxial compression(equal inner and outer confining pressures) tests，the test ability of the hollow cylinder torsional apparatus for rock and the feasibility of hollow cylindrical specimen were verified. It is shown that the hollow cylindrical triaxial compression test(different inner and outer confining pressures) can reflect the influence of the intermediate principal stress on strength parameters. Comparisons of the strength parameters of gray sandstone obtained by different types of experiments were performed，and it is revealed that the strength parameters calculated by the test data of hollow cylindrical triaxial compression test(coupled inner and outer confining pressure) based on D-P criterion can better reflect the influence of the stress state and stress path.

For the purpose of researching the damage evolution law of rock under drying-wetting cycles，the nuclear magnetic resonance(NMR) technique was used to test the weak cementation sandstone under different drying-wetting cycles，and the T2 spectrum distribution，T2 spectrum area and porosity were obtained. The results show that the T2 spectrum curve of rock moves to the right with increasing the number of drying-wetting cycles while the amplitude of the movement diminishes gradually. As the number of cycles increase，T2 spectrum area and porosity rise gradually，but the rate of the growth declines continually. The degree of rock damage is defined by the porosity. The quantitative relationship of the porosity with the rock damage was analysed，and the functional relationship between the number of drying-wetting cycles and the damage degree was established. It is shown that，with increasing the number of cycles，the damage degree to the rock caused by drying-wetting cycles increases while the damage rate decreases. The damage of rock caused by drying-wetting cycles tends to be close to a limit.

Carbonaceous slate is a typical complex rock mass commonly found in the southwestern region. Carbonaceous slate is prone to large deformation and partial collapse during tunnel excavation，and even causes major economic losses and casualties. Taking the Haibaluo Tunnel of the Xiangli expressway as an example，the mechanical characteristics of the large deformation section of the carbonaceous slate tunnel during different stages of the whole construction were investigated based on field monitoring of the displacement of surrounding rock and the internal force of the primary and secondary linings. The research results show that the excavation of the upper step is the main deformation stage of the surrounding rock，and that the deformation of the surrounding rock presents an asymmetrical deformation mode of“smaller at the left and larger at the right” with a maximum settlement(208.9 mm) at the right shoulder. The stress distribution of steel supports along the circumference is“larger at the upper and smaller at the lower”，and the maximum compressive stresses of the upper and lower steps are respectively 550.4 MPa and 134.9 MPa. The safety factors of the vault，the left and right arch shoulders of the primary support and the left invert arch of the secondary lining concrete are less than the limit values. The research results can provide an useful reference for the design，construction of similar projects in the future.

Taking Zhengzhou silt as the research object，the samples were prepared by static and dynamic compaction methods，and a series of triaxial shear tests and mercury injection tests were carried out to study the influence of different sample preparation conditions on mechanical behaviours and pore structure distribution of silt. The results show that the influence of the sample preparation method and the water content on the stress and strain relationship depends on the confining pressure. The stress and strain relationship of dynamic compaction samples transfers from the strain softening type with lower confining pressure and lower water content to the strain hardening type with larger confining pressure and larger water content，while the relationship of static compaction samples is always the strain hardening type. The shear strength and the cohesion of the samples obtained by the two sample preparation methods reach the maximums at the optimal moisture content. The shear strength and the cohesion of the dynamic compacted samples are higher than those of the static compacted samples for the case of the same water content，while the sample preparation method has no obvious influence on the residual cohesion of silty soil. Mercury injection test results indicate that，compared with the dynamic compaction samples，the pore diameter distribution curve of the static compaction samples shifts to the right as a whole，the peak pore diameter and distribution density increase and the larger pore content is more. The research results can explain the evolution law of the mechanical property of the static and dynamic compaction samples to some extent.

Lots of research results of the impact of circular shield tunnel construction have been obtained，but there are few studies on the impact of quasi-rectangular shield tunnel construction. Based on the convergent deformation mode of the excavation face of the quasi-rectangular shield tunnel，an analysis method of the free field displacement of the surrounding soil around the quasi-rectangular shield tunnel was proposed by the mirror method，and a simplified calculation method of the deformation of adjacent pipelines induced by quasi-rectangular shield tunnel excavation was proposed based on the Winkler foundation model and by applying the free displacement field of the soil to the underground pipeline structure. Through the analysis of engineering examples，the free field deformation of the soil was compared with the measured data. At the same time，the finite element numerical simulation method was used to compare the calculation results of the vertical deformation of the pipeline with the simplified method. In addition，the key parameters of the long side width of the tunnel，the depths of the tunnel and the pipeline，the diameter of the pipeline，the elastic modulus of the pipeline，the compressive modulus of the soil and soil loss parameter were analyzed. The results show that the free field displacements calculated by the mirror method adopting the global free field settlement model of the quasi-rectangular shield excavation face are consistent with the measured values and that the theoretical calculations of the adjacent pipeline deformation by the simplified method are in good agreement with the numerical simulation results. Parameter analysis indicates that the pipeline deformation is sensitive to the long side width of the tunnel rectangle，the buried depth and the elastic modulus of the pipeline. The groove width of the pipeline deformation curve increases significantly with increasing the width of the long side of the shield rectangle，and the pipeline deformation respectively increases and decreases significantly with increasing the pipeline depth and the elastic modulus of the pipeline.