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.

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.

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.

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.

In order to study the deformation law of soft rock tunnels within high geo-stress, the paper quantitatively analyzed the relationships between the deformation value with the compressive strength of rock mass, the integrity of surrounding rock, the geo-stress & depth of tunnel, the coefficient of lateral stress, the ground water, the value of basic quality［BQ］ and the stiffness of support of soft rock tunnel within high geo-stress based on the statistics of monitoring dada from 68 monitoring sections in 41 tunnels. The results indicated that the large deformation of surrounding rock in soft rock tunnel within high geo-stress was the outcome of the comprehensive action of geological conditions of surrounding rock, the design and construction parameters and other factors. Among them, the in-situ geo-stress, surrounding rock characteristics and supporting countermeasures had the significant influence. The results from the case statistics could preliminarily reveal the development level of the control technology of large deformation of soft rock traffic tunnel within high geo-stress in China. The deformation of soft rock tunnel within high geo-stress had noticeable time-space effect with the variation patterns from the rapid growth stage to the continuing growth stage and then the stabilizing stage at last with time. The deformation coordination coefficient was mostly affected by the excavation with large fluctuations in the early stage, but tended to be stable very soon after the inverted arch was constructed which also verified and emphasized the key role of the ring closure to the deformation control from another perspective. With the increase of large deformation grade, the proportion of the deformation after construction of inverted arch decreased.

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.

The research background was the construction of large-scale lined cavern gas storage for a deep anhydrite ore body in Anhui province, the thermal-mechanical coupling analysis method based on ABAQUS finite element software was used, established numerical model under the gravity stress field, the deep cavity multi cycle under different cavern spacing was apart from the temperature, the gas extraction in the process of filling the key stratum structure deformation, stress distribution and the change process.The distribution law of surrounding rock plastic zone and the change process of surface deformation under different cavern spacing were investigated.The results showed that the temperature of the main structural layers was not affected by increasing the cavern spacing.When the cavern spacing was less than 2 times the hole diameter, changing the cavern spacing had obvious effects on the stress and deformation of key structural layers, surface displacement, tensile stress distribution and size of concrete lining, and plastic zone distribution of surrounding rock, and the interaction between gas storage was more significant.When the cavern spacing increased to 2 times the cavern diameter, the interaction between gas storage was no longer obvious, and the increase of cavern spacing had no obvious effect on the stability of gas storage.

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.