Numerical Simulation Of Stability Of Underground Cavern Under Static And Dynamic Loads

With the development of my country’s economy and the acceleration of modern urban construction,the development and utilization of underground space has undergone unprecedented development,and various underground space projects of different scales have been implemented.The design of anti-blast safety protection is one of the key technical issues that must be considered during the construction of underground engineering.For example,the stability evaluation of the surrounding rock of underground engineering under the impact of super-equivalent explosives(such as the explosion of a nuclear bomb in the ground)involves both shock waves and underground rock masses.The complex dynamic interaction process with the supporting structure and the influence of the history of static construction action such as the excavation and support of underground engineering are the hotspots and diffculties in engineering and academic research.It is imminent to establish an underground cavern surrounding rock stability and supporting structure safety analysis method that fully considers the dynamic and static processes.The use of fine finite element numerical simulation focuses on how to quickly carry out the rapid simulation analysis of underground caverns under dynamic and static loads,and how to consider static and dynamic forces.Under the combined effect of combined action and dynamic and static loads,the factors affecting the stability of the surrounding rock of underground caverns and the effects of different supporting structures have been systematically carried out on the stability evaluation and analysis of underground caverns under the combined action of dynamic and static loads and the research on the design of anti-blasting support.Research results:(1)The secondary development of ABAQUS based on Python language was constructed to consider the geometric dimensions of the cavern(cavity type,size)and the infinite element boundary of the model,the characteristics of the cavern surrounding rock,the characteristics of the explosion load,the initial stress field,the damping coefficient,and the construction process of the excavation.The automatic modeling method of other elements,the development of an automatic post-processing method that can output the response of the mechanical variables of the key points,realizes the rapid analysis of the stability of the surrounding rock of the underground cavern under the combined action of intelligent and static.(2)It is assumed that the destruction of underground caverns under the combined action of dynamic and static is the result of the continuous deterioration of the static damage zone under dynamic action.Based on the principle of strength reduction,a numerical simulation method for the stability of underground caverns under dynamic action is constructed considering the historical effect of static forces.Based on the analysis of the failure characteristics of the rock mass,a new method based on the increase ratio of the plastic zone area and the increase ratio of the displacement as the stability criterion of the surrounding rock of the underground cavern under the combined action of dynamic and static is proposed.(3)The influence of buried depth,cave type,peak load,surrounding rock grade and lateral pressure coefficient on the stability coefficient of cavern under the combined action of dynamic and static loads is systematically studied,and the quantitative relationship between the stability of underground caverns and the influencing factors under the combined action is revealed.(4)A study on the anti-blast performance of lining and prestressed bolt support was carried out.Through a comparative analysis of the anti-blast characteristics of the two types of support,it was found that the lining is more conducive to limiting the vibration response of the cavern,and the prestressed bolt is more conducive to confining the cave.Deformation of the chamber.Further through sensitivity analysis,the study shows that with the change of support properties,the dynamic response of the surrounding rock of the cavern is weakened within a certain range,and the deformation of the surrounding rock is reduced.(5)A study on the anti-blast performance of the cavern under the combined support of prestressed bolts and linings has been carried out.The results show that the combined support structure can give full play to their respective advantages under the combined action of dynamic and static and can significantly improve the anti-blast performance of the cavern.performance.On this basis,combined with the analysis of the influence of the sandwich foam composite lining material on the anti-blast support performance of the cavern,a new anti-blast support structure was proposed and its performance was verified.The study puts forward a new idea for the stability evaluation of underground caverns under the combined action of dynamic and static,and enriches the theoretical basis for the design of anti-blast support for underground caverns.