基于统一强度理论的隧洞弹塑性应力解析

Elastoplastic stress analysis of tunnel based on the unified strength criterion

基于统一强度理论对第一主应力为径向应力及环向应力2种情况进行弹塑性应力分析,推导得出了围岩应力及塑性区半径计算公式。隧洞围岩有完全弹性状态、最大主应力为径向应力的弹塑性状态及最大主应力为环向应力的弹塑性状态3种状态,隧洞弹塑性分析时,首先判断围岩所处状态,进而选择正确的公式进行计算。分析结果表明中间主应力有利于围岩充分发挥其强度潜能,从而提高隧洞围岩稳定性,而且中间主应力系数越小,围岩稳定状态对中间应力敏感度越高;当洞内压力小于第二临界应力时,增大洞内压力有利于提高围岩稳定性,而当洞内压力大于第二临界应力时,则围岩稳定性随洞内压力增大而降低。

Based on the unified strength theory,the elastic-plastic stress analysis is carried out under the premise that the first principal stress in two cases of radial stress and circumferential stress,and the formula of the radius of the surrounding rock and the plastic zone is derived. Tunnel surrounding rock has three states including the elastic state,the elastoplastic state that the maximum principal stress is the radial stress and the elastoplastic state that the maximum principal stress is the circumferential stress.When the elastic-plastic analysis was carried out on the tunnel,the state of the surrounding rock should be judged and the correct formula is chosen to calculate. Analysis results show that the intermediate principal stress is benefit to the rock to give full play to the strength of the potential,so as to improve the stability of surrounding rock of the tunnel and the smaller intermediate principal stress coefficient,the higher sensitivity of the surrounding rock stability to the intermediate stress. When the inside pressure is less than the second critical stress and increasing the hole pressure is beneficial to improving the stability of surrounding rock,while the hole pressure is greater than the second critical stress,the stability of surrounding rock will reduce with the increase of the hole pressure.