Stability Analysis of Surrounding Rock of Shallow Buried Unsymmetrical Loading Tunnel Excavated by CRD
In order to compare and analyze the stability differences between the shallow buried unsymmetrical and symmetrical loading tunnels were excavated by the cross diaphragm method(CRD),as well as the influence of sur-rounding rock parameters on the safety factors.A numerical simulation model was established to analyzes the stability of tunnel surrounding rock by the strength reduction method.The results indicate that the settlement and horizontal displacement continuously increase with the expansion of the excavation area when the shallow buried unsymmetri-cal loading tunnel in V grade surrounding rock excavated by cross diaphragm method.After the initial support is closed into a ring,the plastic strain value of the surrounding rock decreases,and the stability of the surrounding rock is significantly improved;The maximum settlement is 23.83 mm when the safety factor is 1.6;In V grade sur-rounding rock,when the symmetrical loading tunnel safety factor is 2.2,the maximum settlement is 23.71 mm.The settlement and horizontal displacement growth rate of symmetrical tunnel is relatively slow with the reduction coeffi-cient enlarge.The stability significantly higher than that of the unsymmetrical loading tunnel;With the surrounding rock grade decreases,the settlement and horizontal displacement of the bias pressure tunnel decrease,and the safety factor increases.
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