School of Mechanics & Civil Engineering,China University of Mining & Technology (Beijing),Beijing　 100083,China

针对巷道围岩受两向不等压地应力作用下的平面应变问题，分析围岩流变特性对其塑性区的影响。深埋巷道围岩因流变的发展而持续变形，其达到稳定后的峰值应力为一定围压下的长期强度。基于此，以皖北恒源煤矿-950 m进风井井底车场巷道为例，通过三轴压缩与蠕变试验测定了巷道岩石的抗压峰值强度、长期强度和残余强度。然后，考虑岩体峰后脆性软化特性将巷道围岩分为弹、塑性区，并从既有文献轴对称应力场塑性区公式出发，结合围岩总荷载不变的规律推导了两向不等压巷道围岩水平(及竖向)轴上的塑性区半径，再结合既有文献求解的塑性区形状，相对准确地给出了两向不等压巷道围岩塑性区边界的近似解。该近似解在不考虑岩体峰后脆性软化时的结果与既有文献给出的相应解析结果完全吻合;并且轴对称应力场圆巷围岩塑性区半径的解析解是该近似解在侧压系数为1时的特例。最后，结合试验数据，就考虑岩体流变特性与否的两种情况进行了对比。结果表明:考虑流变，视岩石长期强度为围岩峰值应力，得到的塑性区范围与工程实际基本吻合;否则围岩仅产生弹性变形，与实际偏差较大。可见，岩体流变特性对围岩塑性区分布具有重要的影响，理论研究及工程实际中，忽视岩体流变特性实则无形中高估了围岩岩性，不利于巷道围岩长期稳定性与安全性的评估。

Based on the plane strain problem of roadway surrounding rock under unequal crustal stresses in two direc- tions,the effect of surrounding rock rheology on its plastic zone is studied. The deep-buried roadway sur-rounding rock usually has the characteristics of continuous deformation due to the development of rheology,and the peak stress after stabilization is the long-term strength under a certain confining pressure. Based on this,taken the surrounding rock from the bottom station roadway of the ventilation shaft at -950 m level in Hengyuan Coal Mine in Northern Anhui, China,the peak compressive strength,long-term strength and residual strength of roadway rock are measured by triaxial compression and creep tests. Considering the rock post-peak brittle softening,the roadway surrounding rock may be di- vided into elastic zone and plastic zone. On the base of the formulas of plastic zone under axisymmetric stress field in the existing literatures and the constant assumption of the total loads,the plastic zone analytical radius on horizontal (and vertical) axis of roadway surrounding rock under non-uniform stress field is derived. Then combining with the plastic zone shape determined by the method from the existing literatures,the plastic zone of surrounding rock under unequal compression in two directions is relatively accurately determined. The study shows that the result of the pro- posed algorithm is in perfect agreement with the corresponding analytical one presented in the existing literatures if the post-peak brittle softening of rock mass is not considered. The plastic zone analytical radius of circular roadway sur- rounding rock under axisymmetric stress field is a special case of the proposed algorithm for the lateral pressure coeffi- cient 1. Finally,together with the experiment data and compared the differences of considering the rock rheology to without it,the results show that the broken rock zone by considering the rock rheology is basically consistent with the engineering practice,which is the long-term strength under a certain confining pressure takes as the peak stress of sur- rounding rock. Otherwise,there will be only elastic deformation in surrounding rock,which is much different from the actural situation. It can be seen that the rock rheology has great impact on plastic zone of roadway surrounding rock. Therefore,ignoring the influence of surrounding rock rheology is actually overrating the feature of surrounding rock in theoretical research and engineering practice,which is not good for the long-term stability and safety evaluation of roadway surrounding rock.

DONG Hailong,GAO Quanchen. Approximate solution on plastic zone of roadway surrounding rock under unequal com- pression in two directions by considering rheology[J]. Journal of China Coal Society,2019,44(2):419-426.