The Stability Of EPB Rectangular Pipe Jacking Tunnel Face

To ensure the stability of excavation face is the key to the smooth construction andreduce the impact on the around environment in the construction of EPB rectangularpipe-jacking.In recently, the study on the stability of excavation face is based oncircular shield tunnel, but the research about EPB rectangular pipe-jacking in sand andgravel stratum is less, still in the exploration stage.In this paper, numerical simulation numerical simulation and field monitoringmethod is used to analysis the active damage and passive damage law of InnerMongolia University of Science and Technology under-passing engineering pipejacking face soil research in sand and gravel stratum. The main contents and results areas follows:(1) Based on wedge model made by the previous, by comparing measured data,simulation results with analytic model, proposing an improved model which is suitablefor the pipe-jacking construction through Baotou layer in sand and gravel stratum. Themodel modified the wedge in traditional silo model into trapezoidal wedge, is morecloser with actual damage model. The results showed that the analytic model is coincidewith numerical simulation results in calculate the limit support pressure.(2) Numerical software of FLAC3D was used to simulate the soil instability andfailure modes on tunnel face with different supporting stress. Analysed the regular ofdeformation and failure mechanism on rectangular pipe-jacking face, put forward thesuggestion that the limit supporting stress equal to0.165which guide the constructionof the EPB rectangular pipe-jacking face support pressure control.(3) Make a detailed analysis of the law of excavation face deformation anddamage when the face is under the unbalanced stress. The results showed that when thetwo cutter blockage have the most serious effect on the stability of the soil face,especially when1#and3#cutter blockage at the same time. The limit supporting stressequal to0.19lead to soil displacement increasingly rapid, destruction of soil instability (4) occurs. Given a theoretical basis for the actual project and the limit pressure iscalculated to ensure the excavation face stability through solving actual engineeringjacking force uneven situation.The research results may provide a demonstration effect on the future of the sandand gravel stratum in rectangular pipe-jacking construction, will have importantpractical value and theoretical significance.