Study On Stability Control Of Surrounding Rock During TBM Excavation In Soft-rock Horizontal Tunnel

The instability and unloading of surrounding rock in roadway under excavating disturbance can easily induce large-scale caving of rock mass in heading face,even leading to the dynamic disaster of surrounding rock,which seriously restricts safe and efficient excavation in the field.Because of its safety,high efficiency,high quality,environmental protection and stability favorable to surrounding rock,TBM(tunnel boring Machine)full section Hard Rock tunneling technology will be the preferred method to guarantee the construction of large base of coal production,which has important engineering significance for safety excavation.Based on the engineering background of the TBM construction of the auxiliary flat tunnel in the flood Dam Bay of Shenhua Xinjiang Energy Co.,Ltd.,the stability control of the surrounding rock of the auxiliary horizontal tunnel under the condition of construction of soft rock was carried out by means of investigation on field,theoretical analysis,physically simulating experiment,numerically calculating and engineering application.Through investigation on field,rock mechanics experiment and theoretical analysis,in this paper,the geological situation of 120m argillaceous rock strata is analyzed,which shows that the characteristics of rock and soil are complex,the classification of surrounding rock is low,loose and weathered,layered soft,and types of failure and instability of rock have diversity and complexity.The driving process is easy to lead to dynamic disaster;by constructing model experiment on physical similarity of TBM construction in tunnel,the mechanism of deformation of rock,failure caving,dynamic compaction and evolutionary process on instable disaster under disturbance of excavation is revealed.By means of three-dimensional finite difference numerical method,the temporal and spatial characteristics of evolution of overlying strata in the course of tunneling are revealed,The results show that with the continuous advancement of TBM,the maximum settlement in the roof is widest damaged area and the second is palm surface,the settlement of roof of roadway under the condition of notsupporting and segment support is analyzed,and the settlement of the segment support is one half times lower than that of the tunnel under the no supporting State with the continuous depth of excavation.The peak stress decreases and is linearly distributed.According to the theory to elastic hole,the optimized segment support parameters are designed,combined with the engineering example under the condition of TBM constructing segment support.Based on the SIR-20 geologic radar to scan and monitor the segment support area,it is very good to monitor the density of the surrounding rock supported by the display wall,and the elastic-plastic influencing range of the top floor is controlled effectively by the segment support.After the tube is added to the wall,the surrounding rock is tightly continuous,the support effect achieves the expected goal,the control effect is good,and the safety excavation is realized.The results could provide great scientific significance and value of guidance for supporting technology of roadway under the condition of TBM construction in soft rock adit.