岩体剪胀对巷道围岩塑性区位移的影响分析

Influence Analysis of Rock Dilatancy on Plastic Zone Displacement of Surrounding Rock of Roadway

为研究巷道围岩塑性区的力学性质,考虑岩体剪胀特性及巷道塑性区的弹性变形,采用H-B准则和非关联的流动准则对圆形巷道进行理论分析,通过在弹塑性交界处的应力连续条件,得到了塑性区半径和位移的H-B新解;结合算例分析了剪胀特性对围岩塑性区位移的影响,并与M-C准则解作对比。分析结果表明:岩体剪胀系数越小,M-C与H-B准则计算出的塑性区位移吻合度越好;随着剪胀系数的增大,吻合度下降,围岩塑性区的位移也会增大,在弹塑性交界处,文中H-B准则解在不同剪胀系数条件下塑性区位移相等,而M-C准则解不等,理论上证明了本文解的准确性。

For further study the mechanical properties of the axisymmetric roadway surrounding rock, Hoek-Brown criterion and non-associated flow rule are used as elasto-plastic analytical method of circular roadway by considering the effect of the rock dilatancy characteristics and elastic deformation in the plastic zone. Using the conditions that the stress is continuous at the elastic-plastic interface, a fully analytical solution for Hoek-Brown failure criterion is proposed for the displacement and radius of plastic zone. Illustrative examples are given to demonstrate the performance of the proposed solution and compare with the MohrCoulomb failure criterion. The results obtained by the proposed solution indicate that, the M-C and H-B criteria are in good agreement when the dilatancy characteristic is small. With the increase of dilatancy coefficient, the agreement of the M-C and HB criteria is failing and the displacement of plastic zone increases with the increase of dilatancy coefficient. At the elastic-plastic interface, the displacement of the plastic zone is approximately equal based on H-B criterion with different dilatancy coefficients,while the M-C solution is not equal, which theoretically proves the accuracy of solution.