考虑中间主应力与渗流作用的巷道稳定理论解

为了探究渗流作用下不同中间主应力对圆形巷道围岩的影响,应用弹塑性力学理论,基于Drucker-Prager屈服准则,推导得出围岩塑性区半径与孔隙水压力之间的关系式;再由极值点失稳理论,确定围岩失稳的判别准则。结合实际工程,分析中间主应力系数对临界水压力的影响,结果表明:中间主应力对临界水压力有较大影响,采用D-P准则时中间主应力系数与临界水压力的关系曲线表现为类抛物线形式。当中间主应力系数取0.8时临界水压力达到最大值10.0 MPa;与基于MC准则的计算结果做对比,发现考虑中间主应力时D-P准则的临界水压力计算结果更能反映岩石多轴力学性能,可应用于较为完整的含水岩层支护设计优化。

Theoretical solution of roadway stability considering intermediate principal stress and seepage

In order to explore the influence of different intermediate principal stresses on the surrounding rock of circular roadway under seepage, the relationship between the radius of the plastic zone of the surrounding rock and the pore water pressure of the surrounding rock is derived based on the Drucker-Prager yield criterion by applying the elastoplastic mechanical theory. Then, the extreme point instability theory is used to determine the discriminant criterion of surrounding rock instability. Combined with the actual engineering, the influence of the intermediate principal stress coefficient on the critical water pressure is analyzed, and the results show that the intermediate principal stress has a great influence on the critical water pressure, and the relationship curve between the intermediate principal stress coefficient and the critical water pressure is shown in a parabolic-like form when the D-P criterion is adopted. When the intermediate principal stress coefficient is 0.8, the critical water pressure reaches a maximum value of 10.0 MPa. Compared with the calculation results based on MC criterion, it is found that the critical water pressure calculation results of D-P criterion when considering the intermediate principal stress can better reflect the multiaxial mechanical properties of rocks, and can be applied to the optimization of more complete support design of aqueous rock formations.