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为研究侧压力系数对巷道周边岩体稳定性的影响,以一条深埋圆形巷道工程为背景,采用离散颗粒元软件PFC3D分析了5种侧压力系数下巷道周边岩体的应力差、位移、破裂分布模式和微裂纹数等,得到了圆形巷道周边岩体应力、变形和破裂随侧压力系数的变化规律。结果表明,1)随侧压力系数增大,巷道顶底部浅部岩体主应力差先增大后减小,深部岩体主应力差逐渐增大;而巷道两帮浅部岩体主应力差变化较小,深部岩体主应力差先减小后增大。这表明在相同埋深情况下,高侧压力系数不一定会对帮部岩体造成更大的破坏,但更容易使顶板产生高剪应力,不利于顶板岩体的稳定。2)侧压力系数越大,巷道顶板岩体竖向位移就越小,且其由拱顶往外平滑递减的规律性也越不明显,而帮部岩体水平位移变化规律与顶板岩体相反。3)巷道顶底部围岩在侧压力系数较大的情况下较易发生破裂,并随侧压力系数增大,其破裂范围越来越大;巷道两帮岩体则在不同侧压力系数下均会发生破裂,且其破裂范围随侧压力系数增大而略减小。4)不同侧压力系数下,巷道岩体总裂纹数都随开挖时间呈指数增长;且当巷道开挖完成后,岩体总裂纹数与侧压力系数呈抛物线关系。
In order to study the influence of lateral pressure coefficient on the rock mass stability around the roadway, based on a deep buried tunnel project, the discrete element software PFC3D was used to analyze the stress difference, displacement, Rupture distribution patterns and the number of microcracks, the variation law of stress, deformation and rupture with lateral pressure coefficient of rock mass surrounding circular tunnel is obtained. The results show that: 1) With the increase of lateral pressure coefficient, the main stress difference of the top and bottom rock mass first increases and then decreases, and the main stress difference of the deep rock mass gradually increases; The change is small, the main stress of the deep rock mass first decreases and then increases. This indicates that under the same depth, the high side pressure coefficient will not necessarily cause more damage to the rock mass, but it is easier to make the roof produce high shear stress, which is not conducive to the stability of roof rock mass. 2) The larger the lateral pressure coefficient is, the smaller the vertical displacement of the top rock mass is, and the less obvious the regularity of its decreasing from the vault is. The horizontal displacement of the rock mass is opposite to the top rock mass. 3) The surrounding rock at the top and bottom of the roadway is more prone to rupture when the lateral pressure coefficient is larger, and the rupture range is larger and larger as the lateral pressure coefficient increases; Will rupture, and its rupture range slightly decreases with the increase of lateral pressure coefficient. 4) Under different lateral pressure coefficients, the total crack number of roadway rock mass increases exponentially with the excavation time; and when the roadway excavation is completed, the total rock crack number and the lateral pressure coefficient have a parabolic relationship.