Study On Ground Deformation Discipline And Control Techniques Of Subway Tunnel Excavation Under The Influence Of Strata Defect

ABSTRACT: As we stepped into the21th century, the major cities construct in full swing, which brings convenience and comfort to everybody. The government takes big attention to the rail transport and sees it as an important support to the city expansion. Big rail construction-boom appears in the major cities such as Beijing, Shanghai and Guangzhou. Subway excavations bring adverse effect inevitable. It will take disturbance to the environment, asymmetric settlement to the buildings or structures which conducts the cracks on the buildings or the concrete pipes. Substructure work will often encounter undesirable strata defect, the randomness of which will bring some unforeseeable sequent to the work. The strata defect will always result in the engineering accident or the big trouble to the staff in the actual practice. As a result, the ground discipline and control of tunnel excavation become to a stubborn problem to be worked out in the rail transport construction boom.We adopted the methods of investigation, model test, numerical simulation and field operations to study the problem of settlement and failure of the stratum, the control method under the condition of strata defect, based on the work of Beijing and Changchun tunnel excavation. The main conclusions are as follows:(1) By investigation of the adverse geological body in the subway construction, we make a summary of the types of adverse geological body and then educe the conception of strata defect.(2) We monitor and study the deformation and stress of stratum under the condition of hole or nothing by the similar test, and obtain two types of surrounding rock failure.(3) Based on the Mohr-Coulomb yield rule, we study the deformation and failure of stratum under the conditions of different distribution holes by numerical simulation and bring out some rules in these two aspects.(4) We study the control method of strata defect under the construction of tunnel with geological forecast, monitoring, and injecting which shows the practicability and good effect.