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 water inrush disaster that was easy to occur during tunnel construction, the internal law of tunnel water inrush was analyzed through the statistics cases of tunnel water inrush. The water inflow in tunnels during construction was predicted by using the methods of long short-term memory neural network(LSTM), Elman neural network and multiple linear regression based on partial least square respectively, and compared with the actual water inflow, then the optimal method for predicting the tunnel water inflow was obtained. The results showed that water inrush accidents were more likely to occur in shallow-buried, long tunnels and extra-long tunnels, and in fault, karst and soluble rock strata. By comparing the prediction results of three different models with the water inflow during tunnel construction, the LSTM model had higher accuracy in predicting the water inflow in tunnels during construction.

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.

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 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.

Aiming at the water inrush disaster that was easy to occur during tunnel construction, the internal law of tunnel water inrush was analyzed through the statistics cases of tunnel water inrush. The water inflow in tunnels during construction was predicted by using the methods of long short-term memory neural network(LSTM), Elman neural network and multiple linear regression based on partial least square respectively, and compared with the actual water inflow, then the optimal method for predicting the tunnel water inflow was obtained. The results showed that water inrush accidents were more likely to occur in shallow-buried, long tunnels and extra-long tunnels, and in fault, karst and soluble rock strata. By comparing the prediction results of three different models with the water inflow during tunnel construction, the LSTM model had higher accuracy in predicting the water inflow in tunnels during construction.

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 selection of ventilation modes during the construction of a large underground cavern storage, according to the ventilation design of a large underground cavern storage, on the basis of comparing the advantages and disadvantages of the extraction type, the press-in type and the mixed type ventilation mode, and according to each ventilation mode calculate the air volume according to the method was calculated, and the ventilation mode of each stage of the construction of the large underground cavern storage was determined. A Ventsim numerical simulation model for ventilation of a large underground cavern storage was constructed, and numerical simulations were conducted to study the dynamic evolution law of wind flow in a large underground cavern storage with different ventilation modes in different construction stages, and the differences in different construction stages were analyzed. The ventilation effects of the ventilation methods were compared and analyzed, and the ventilation methods in different construction stages were optimized. The numerical simulation results showed that the optimal ventilation mode in the first construction stage was press-in ventilation, the optimal ventilation mode in the second construction stage was mixed ventilation, and the optimal ventilation mode in the third and fourth construction stages were extraction ventilation. At the same time, it was verified that the effect of wind resistance, air volume and air network efficiency of each ventilation method in different construction stages was optimal, which provided a scientific basis for the ventilation design of large underground water-sealed caverns during the construction period.

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.

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.

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 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.

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.