Study On Deformation Law Of Surrounding Rock Of Shield Machine Passing Through Filling Cave

By means of field investigation,laboratory test,numerical simulation and model test,the treatment of karst caves in front of shield tunneling is deeply studied and verified by Jinan Metro R1.This paper summarizes the treatment measures and materials used in more than 20 subway projects across the country in the distribution of karst caves,and compares the advantages and disadvantages of common grouting materials.In this paper,the mechanical parameters of field rock samples are measured by basic mechanics tests,and the numerical simulation process of uniaxial compression of limestone is established by combining the discrete element software EDEM.The meso-parameters of EDEM simulation model is calibrated by comparing the stress-strain curves of limestone between laboratory tests and numerical simulation.When the normal contact stiffness is 1 X10~8 N/m~3,the tangential contact stiffness is 7×10~8N/m~3,and the critical normal stress and the critical tangential stress are 5×10~8 Pa,the bonding parameters can better simulate the mechanical properties of limestone.A three-dimensional mechanical model of shield machine is constructed based on Solidworks software,and the motion attitude simulation of the model in EDEM simulation environment is realized.A discrete element numerical model for shield tunneling through karst cave filling is established.Six construction conditions are designed according to the strength of filling materials.The simulation results show that the ratio of strength of filling materials to surrounding rock strength in front of shield tunneling should be set between 0.8 and 1.2.A model test device for composite Earth Pressure Balanced shield is developed,which includes two parts:a test machine and a model test box.According to the similarity theory of model test and the mechanical properties of original rock,the similar materials are allocated.The model test of shield tunneling through karst cave by filling is carried out with the equipment and materials.The variation law of surrounding rock physics information is analyzed.The test result shows that the disturbance range of shield tunneling to tunnel surrounding rock is about 0.5D in front of cutter head,1D behind cutter head and 2D in radial directio n of tunnel.The main innovations of the thesis include:The correlation criterion between limestone mechanical parameters and EDEM mesoscopic parameters is established,which provides a model basis for discrete element method to simulate rock.The model representation of the shield machine in the EDEM simulation environment is realized,and the shield tunneling process is simulated.A composite earth pressure balance shield test machine was developed,which revealed the influence of the filling strength of the karst cave on the stability of the surrounding rock when considering the shield disturbance.