The paper reviewed the experimental research progress of prefabricated drilling and high stress real-time drilling in analyzing the mechanism of drilling pressure relief(DPR)for preventing rockburst disasters from the perspectives of macroscopic(mechanical behavior characteristics, failure characteristics, energy evolution)and microscopic(crack evolution), and elaborated on the rationality and effectiveness of DPR for preventing rockburst disasters. Theoretical research and experimental analysis had confirmed that DPR was a key technology for relieving high stress and high energy in deep surrounding rocks, providing a reference for optimizing the application of DPR to prevent rockburst. High stress real-time drilling test method was a more scientific new research method that revealed the internal mechanism of DPR to prevent rockburst. Based on this, six development directions had been proposed for the experimental research on the mechanism of rockburst induction and the current technical conditions of multifunctional testing systems to analyze the mechanism of DPR to prevent rockburst: developing high-stress drilling rig test equipment compatible with true triaxial test systems; considering disturbance factors in high-stress real-time DPR simulation tests; simulating real-time DPR test after excavation of deep tunnels(roadway)("3D six-sided loading-single-sided unloading-real-time DPR" test); constructing an analytical model for the energy evolution of surrounding rock under 3D high stress real-time DPR; exploring the relationship between the spatial size effect of pressure relief drilling and the stress field and internal energy dissipation mechanism of surrounding rock; establishing a computational model for rockburst prevention by DPR in large-scale high-stress surrounding rock based on numerical simulation software.

In order to probe into the similarities and differences of the stress-deformation law and the reinforcement effect of shield tunnel strengthened with corrugated steel under complex stress paths, a refined model of three-ring staggered joints was established based on the finite element software MIDAS GTS NX, the effect of corrugated steel reinforcement was evaluated from the angle of convergent deformation, corrugated steel stress and plastic deformation of segments before and after reinforcement, the stress and deformation evolution of shield tunnel strengthened with corrugated steel under loading and unloading conditions were analyzed. The results showed that the distribution of the maximum convergent deformation was different in the complex loading environment. The waist was the main part of the loading, and the top and bottom was the main part of the unloading under unloading, the effect of corrugated steel reinforcement was better than that under surcharge loading, and the maximum reinforcement efficiency could reach 70%, the convergent deformation and the stress development of corrugated steel with different plate thicknesses were similar and showed a linear increasing trend, while corrugated steel could effectively delay the plastic development of concrete, however, the ability of stagger suppression between rings under unloading condition was weak.

Based on rheological mechanics and viscoelastic mechanics, a theoretical model for the coupling of prestress loss of anchor and creep of rock was established. Considering the influence of prestress loss when the prestressed anchor was used to reinforce rock mass, the creep equations of stable creep rock and unstable creep rock were derived, and the formula for calculating prestress of anchor with time was obtained. The results showed that the anchor prestress loss was faster in the period of completion of anchor tension; then the rate of prestress loss was gradually reduced and finally stabilized, and the creep of rock also became stable. By comparing the calculated results with the experimental results in existing literature, the curves of the two were consistent, which verified the correctness of the model. The comparison between the variation of anchor cable prestress at Jinping Hydropower Station and the calculation results of the theoretical model proves the accuracy of this research model applied to engineering examples. The theoretical analysis results established in this paper considering the coupling of anchor cable prestress loss and rock mass creep have a wider application range than previous coupling models, which is not only applicable to stable creep rock, but also to unstable creep rock. The warning of abnormal changes in anchor cable anchoring force and the long-term safe operation of slope engineering have extensive engineering application value.

Peridynamics theory is a new meshless method. Based on the microelastic brittle model inperidynamics, a kernel function that can reflect the internal length effect of the long-range forces varies with the distance between material points is introduced. The numerical solution program of dual-borehole rock blasting under high in-situ stress state was written by Fortran language to investigate the dynamic deformation and failure process of dual-borehole rock blasting under different borehole distance, in-situ stress states and lateral pressure coefficients, and the whole process of crack initiation, propagation and coalescence in dual-borehole rock blasting was obtained. The results showed that the crack area enlarges from 306.59 cm² to 449.07 cm² with the increase of the borehole spacing from 100 mm to 200 mm, whereas the borehole spacing rised to 200 mm, the cracks was unable to throughout which was produced by dual-borehole. At the hydrostatic in-situ stress levels, with the increase of in-situ stress, the crack propagation time reduced, the initial time of rock failure postponed, the damage area reduced from 123.24 cm² to 32.96 cm², and the main crack propagation length decreased from 87.73 mm to 14.42 mm. Under non-hydrostatic in-situ stress, the crack propagation tended to the direction of maximum principal stress. With the increase of lateral pressure coefficient, the damage area diminished and the directivity of crack propagation became increasingly apparent.The in-situ stress inhibited the crack propagation of rock, and the non-hydrostatic in-situ stress exerted a guiding effect on the crack propagation. In reality, the efficiency of rock fragmentation will be improved through selecting proper borehole distance and arranging the blasting holes along the direction of maximum principal stress which are beneficial to forming a new free surface.

Aiming at the poor geological conditions of water conveyance tunnel in Lanzhou water source construction engineering by double shield TBM excavation, the comprehensive methods and treatments were put forward by data statistics, engineering analogies, and other methods. Before TBM tunneling, F₃ fault zone and F₈ fault zone were excavated by drilling and blasting method. After initial support which guaranteed the stability of surrounding rock, TBM slided through and installed segments. Based on geological analysis along tunnel, combination the observation of tunneling face, rock muck analysis and tunneling parameter analysis, the geological conditions of surrounding rock in front of tunneling face were comprehensively predicted by using three-dimension seismic method and three-dimensional resistivity method. The principle of "drainage first, drainage and plugging combined" was adopted, the variable slope drainage system was established, the operation mode of the drainage system was determined according to the amount of water gushing. According to the characteristics of the front shield blocked, the method of releasing surrounding rock pressure by manual excavation of the heading tunnel from the telescopic shield was adopted to make the TBM out of blocked. Based on identifying geological conditions, the use of chemical grouting and cement grouting consolidation broken surrounding rock, controlling TBM tunneling parameters, slow tunneling through the fracture zone. TBM tunnneling practice shows that the adopted technology is effective and the poor geological conditions have not caused serious consequences for TBM.

In order to verify the effectiveness of the overall operation control mode of the ventilation and smoke exhaust system in V-slope highway tunnel during fire, and to prevent the impact of fire smoke on the safety of personnel outside the tunnel entrance, a full-scale on-site physical fire test was carried out in Jinan Huanghe Tunnel to determine the flow characteristics of smoke and the diffusion of smoke from the tunnel entrance under different conditions. The results showed that when a fire occured in V-slope tunnel, the full jet longitudinal smoke exhaust system could operate effectively. When there was no mechanical ventilation, under the joint action of “chimney effect” and natural wind, the smoke spread distance was different under different fire power. The smoke temperature near the fire source was in the form of pulse, and the stratification was not obvious, while the vertical temperature in the far fire source was obvious. In mechanical ventilation, under different fire power, the average time of mechanical wind generated by the fan acting on the flue gas front was 15 s, which could completely control the upstream flue gas counterflow. After the flue gas exits the hole, the diffusion distance was proportional to the longitudinal wind speed. The safety distance of personnel outside the tunnel entrance was defined.

In order to study the influence of grouting reinforcement on the shear strength of the persistent joint planes, the nonpersistent jointed rock samples were sheared to be failed for preparing the persistent joint plane samples. The direct shear tests on grouting reinforced rock mass were carried out to explore the failure characteristics and mechanical properties of them. The results showed that the failure modes of rock mass after grouting treatments could be divided into three types: grouted plane shearing failure, intact rock material failure and grout consolidation failure. The failure modes were mainly affected by the strength of grouted plane, grout consolidation and rock material. The water cement ratio mainly affected the strength of the grout consolidation and the bond strength of the grouted surface. The filling thickness mainly affected the bonded strength of the grouted surface. Through grouting treatments, the cohesion of rock joint surface was significantly improved, while the internal friction angle was rarely affected. The initial failure of non-persistent jointed rock mass had an impact on the effect of grouting treatments. The strength improvement of grouting reinforcement on tension-induced failure planes was better than that on shear-induced ones.

Taking the work area of 3# Transverse Gallery of Zhongyi Tunnel of Lijiang-Shangrila Railway as the engineering background, the large deformation characteristics of parallel adit and main tunnel under different section forms were analyzed by field deformation monitoring. It was found that the large deformation characteristics of metamorphic basalt tunnel with schistosity were obvious under extremely high ground stress environment, and the horizontal convergence was the main deformation around the tunnel. The effectiveness of tunnel section optimization and support reinforcement measures was verified by numerical simulation verification. The results showed that the deformation of tunnel surrounding rock could be reduced by reducing the sudden curvature change of tunnel section and making the tunnel section symmetrical, adding foot-lock anchor bolts and increasing the strength of steel mesh could effectively control tunnel deformation. Under the joint action, more than 65% of the deformation of tunnel surrounding rock could be controlled, reducing the distribution of plastic zones in the large deformation section of the surrounding rock. These measures had a good control effect on the large deformation of the Zhongyi Tunnel which could provide guidance for railway tunnel construction in complex stress environment.