Shi Chenghua

Study on Influence Factors of Crossing Railway Tunnel Excavation

In order to discuss the excavation influencing rule of crossing railway tunnel, 3 major influence factors including rock grade, cross angle and rock pillar height were taken into account, and 100 numerical models were designed for calculating, and then, the vault settlement and primary supporting internal force of existing tunnel induced by new tunnel excavation were analyzed. The study results show that: with the excavation processing of new tunnel, the vault settlement and primary supporting internal force of existing tunnel getting large, with the rock pillar height, cross angle and rock grade increasing, the increasing ratio of vault settlement of existing tunnel increases, but the increasing ratio of primary supporting internal force decreases, and with the cross angle increasing, the increasing ratio of primary supporting internal force increases.

Calculation of Surrounding Rock Pressure on Shallow Buried Tunnel Using Linear and Nonlinear Failure Criterion

Based on Terzaghi failure mode, calculation method of surrounding rock pressure on shallow buried tunnel was established using linear and nonlinear failure criterion, the modified Terzaghi theory which was extended to complex strata and the corresponding recurrence formulas for calculating vertical earth pressure was obtained by theoretical derivation. The surrounding rock in fractured zone of tunnel side wall was analyzed as isolated body by limit equilibrium method, and the explicit calculation expressions of horizontal earth pressure of shallow buried tunnel was obtained. Case analysis indicates that this method is feasible. And then, the effect of lateral pressure coefficient of overlying strata and nonlinear coefficient to surrounding rock pressure with linear and nonlinear failure criterion was further studied, the results show that the surrounding rock pressure decreases notably with lateral pressure coefficient of overlying strata increasing and decreases slowly with nonlinear coefficient increasing, and the effect of nonlinear coefficient to horizontal earth pressure is somewhat large.