Study on Safety of Tunnel Secondary Lining under Non-Uniform Expansion Force
Expansive rock will expand and deform when it encounters water,and generates expansion loads.Based on the theory of load structure method,the size and distribution of the safety factor of each part of the secondary lining structure for different expansion positions and different expansion loads are calculated and studied,and the variation law of the safety factor of the structure under dif-ferent inverted arch rise span ratio are compared and analyzed.The research results show that:①when the expansion load is 100～200 kPa,the safety factor of each part of the structure is greater than 2.0,and the structure is safe.When the expansion load is 300,400 and 500 kPa,the local safety fac-tor of the structure is less than 2.0,which cannot meet the bearing capacity requirements.The local expansion is more harmful to the structure than the full ring expansion;②When the inverted arch lo-cally generates 300 kPa and 400 kPa expansion load,increasing the rise span ratio of the inverted arch can effectively improve the structural safety state.When the inverted arch generates 500 kPa expan-sion load,other effective engineering measures need to be taken;③When the rise span ratio of invert-ed arch increases to a certain range,the increase of safety factor is less obvious.One or more engi-neering measures should be taken to ensure the stability of the structure.
expansive rock tunnelsecondary liningnumerical calculationload structure methodsafety factor
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