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.

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.

This research summarized the basic concepts of compressed air energy storage(CAES)underground caverns from an engineering perspective, analyzed the basic structure of caverns and the main load characteristics of caverns during operation. On this basis, the basic design concept of flexible sealing structure was put forward, and the reliability design method was suggested to be adopted in the construction of underground caverns, which also provided the guidance and design principles, operation, and maintenance of CAES underground caverns.

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.

In order to explore the main influencing factors and control methods of secondary disasters of water and mud inrush in underground engineering, the prevention and control technology of secondary disasters of water and mud inrush was proposed by summarizing relevant cases since 2010 and the disaster-inducing environment and factors were summarized. Taking the secondary water and mud inrush of Shizishan Tunnel crossing F_Ⅲ-71 fault in central Yunnan as an example, the causes of disasters in this geological section were explored, and the evolution process of secondary disasters was divided into three stages: gestation stage, latent stage and induction stage. The methods of improving the state of the external environment, blocking the evolution path of the disaster and increasing the bearing capacity of the anti-outburst layer were put forward to prevent the recurrence of water outburst and mud outburst, which provided experience guidance for the treatment of the secondary disaster of water outburst and mud outburst.

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.

The development history, cavern composition and role of underground compressed gas energy storage technology were systematically introduced, and the development status of underground lined cavern technology was discussed. This paper systematically analyzed the research progress of three key problems of underground lined caverns, namely ultimate storage pressure, thermodynamic effects in the process of gas injection and production, and sealing performance of cavern lining, summarized the existing research results, pointed out its limitations, and put forward suggestions for the future research direction of underground lined caverns.

This study aimed to enhance shield muck by incorporating foam agent and active magnesium oxide. The fluidity, bleeding rate and compressive strength of the improved soil under different foam agent and active magnesium oxide content were obtained by fluidity, bleeding rate and compressive strength test. It was showed that the improved flowable backfill soil exhibited excellent fluidity and solidified strength. By adjusting the content of foam agent and active magnesium oxide, the flowable backfill soil with fluidity ranging from 180 mm to 320 mm, bleeding rate below 5%, and 28-day compressive strength between 0.6 MPa and 1.2 MPa could be obtained.

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.

Based on the spillway tunnel project of Jinchuan Hydropower Station, this research introduced the microseismic monitoring technology to monitor the deformation and failure of surrounding rock in real time, and studied the spatio-temporal evolution characteristics of microseismic events in surrounding rock of spillway tunnel. The failure mechanism of surrounding rock in spillway tunnel of Jinchuan Hydropower Station was analyzed by means of energy ratio of transverse and longitudinal waves E_S/E_P. The fractal rock mechanics theory was introduced into the field of microseismic, and the spatiotemporal evolution of the fractal dimension of energy released by microseismic was analyzed. The relationship between the fractal dimension and the deformation of surrounding rock in time and space was revealed through the comparative analysis of the evolution law of the fractal dimension and conventional monitoring data. The fractal dimension of the microseismic energy of rock mass before the deformation occured would appear dimension reduction in time and space, which could be used as a warning signal.