圆形洞室应力状态及塑性区分析

Stress state and plastic zone of circular tunnel

为了研究圆形洞室开挖后洞壁围岩和工作面前方围岩的应力状态和塑性区范围,采用数值模拟和理论计算相结合的方法,对不同埋深下的圆形洞室进行了FLAC3D模拟,揭示了开挖后的力学特性。结果表明:对于洞壁围岩而言,随着初始应力的增加,最大的切应力不是线性增加的,其增加的幅度在逐渐减小;而最大切应力与初始应力的比值维持在稳定的范围内。塑性区范围随埋深的增加在逐渐地扩大,但增加的幅度也在减小。对工作面前方围岩而言,切向应力和径向应力逐渐靠近初始应力的速度明显快于洞壁围岩,但其切向应力明显小于洞壁围岩的切向应力;随着埋深的增加,工作面前方最大切应力与初始应力的比值处于缓慢增加的过程;随着埋深的增加,工作面前方围岩的塑性区范围比洞壁围岩的大,进一步验证了工作面处存在应力集中现象。

In order to have a better understanding of the stress state and plastic zone extent of surround- ing rock and rock mass in front of working face of circular cavity under different buried depth, the FLAC3D simulation was carried out combined with theoretical calculation, and the mechanical properties after excavation was revealed. It demonstrates that, for surrounding rock, the maximum tangential stress is not linearly increased with the increase of initial stress, and the amplitude of the increase is gradually de- creasing. However, the ratio between maximum tangential stress and initial stress maintains in a narrow extent. The plastic extent is expanding with the increase of buried depth. For rock mass in front of work- ing face, its stress state is similar to that of surrounding, and the tangential stress and radial stress gradu- ally close to the initial stress level is significantly faster than that of surrounding rock. However, the tangential stress is greatly smaller than that of surrounding rock. The ratio between maximum tangential stress and initial stress maintains increases slowly. The plastic zone is similar to that of surrounding rock, but the extent is bigger, so it verifies the stress concentration in the working face.