Upper Bound Analysis Of Surrounding Rock Pressure And Reliability Study For Roadway Considering Floor Heave Failure

When the coal mine roadway was buried deeply,the geological environment of the area where it was located was complex,and there was obvious in-situ stress,so the roadway was prone to floor heave damage.To solve the problem of roadway floor heave was the key to ensure the safety and efficiency of underground coal mining.In this paper,based on the National Natural Science Foundation of China（51804113,52074116）,the upper bound method of limit analysis was used to construct the failure mode of roadway considering floor heave.The in-situ stress was introduced into the calculation as an additional load,and the analytical expression of the limit surrounding rock pressure of the roadway was derived.Based on this failure mode,the nonlinear Hoek-Brown failure criterion was introduced to study the influence law of main parameters on the limit surrounding rock pressure and potential failure surface of the roadway.According to the reliability theory,considering the randomness and discreteness of the parameters,the reliability model of roadway structure system was established.The failure probability and reliability index were calculated by the response surface method,the wide bound method and the narrow bound method.The allowable failure probability and the target reliability index were introduced to obtain the reasonable safety factor range and reasonable support force range required for roadway support design under different mean value and variation coefficient of random variable parameters.It provides a reference for the design and construction of similar roadways in the future.The main work of this paper was as follows:（1）The failure mode of roadway with floor heave was established,which was composed of “wedge-shaped collapse body of sliding downward + quadrilateral rigid block on the side +triangle block at the bottom”.And according to the principle of virtual power,the expression of limit surrounding rock pressure was derived.The numerical simulation method was used to verify the failure mode,and the results showed that the failure mode constructed in this paper was reasonable.（2）The tunnel failure mode considering the bottom drum was adopted,based on the nonlinear Hoek-Brown failure criterion,the variation law of the limit surrounding rock pressure and potential failure surface of the roadway under typical influence parameters was analyzed.（3）According to the reliability theory,the single failure mode and multiple failure mode reliability models of roadway structure system were established respectively.The failure probability and reliability index were solved by the response surface method,wide bound method and narrow bound method.The advantages and disadvantages of different reliability models and reliability methods were compared and analyzed.（4）Based on the narrow bound method related to multiple failure mode correlation,the influence of different mean values and variation coefficients of random variable parameters on reliability was analyzed.And with the introduction of the allowable failure probability and the target reliability index,the reasonable safety factor range and the reasonable support force range required by the roadway support design were obtained.（5）Combining the actual engineering of coal mine roadway,the theoretical calculation results are compared with the measured data and numerical simulation results.It not only proved the rationality of the failure mode and the feasibility of the calculation method,but also proved the economy of the theoretical calculation results.