有压隧洞围岩最小覆盖层厚度弹塑性力学分析

水工隧洞的最小覆盖层厚度受到多方面因素的影响,如何确定最小覆盖层厚度是水工隧洞设计中必须重视的关键点之一.针对传统的最小覆盖层厚度算法的不足,本文提出了基于采用弹塑性力学方法的优化算法.该优化算法综合考虑了黏聚力、内摩擦角、地质强度指标、施工扰动等因素的影响,得到的最小覆盖层厚度更加符合实际情况.根据水工隧洞运行期的受...

Elastoplastic Analysis on the Minimum Covering Layer Thickness of the Pressure-tunnel Surrounding Rock

The minimum overburden thickness of hydraulic tunnel is influenced by many factors. How to determine the minimum overburden thickness is one of the key points in hydraulic tunnel design. In view of the deficiency of the traditional minimum overburden thickness algorithm, an optimization algorithm based on elasto-plastic mechanics is proposed. This optimization algorithm considers the influence of cohesion, internal friction angle, geological strength index, construction disturbance and other factors, and the minimum overburden thickness obtained is more in line with the actual situation. According to the stress condition of the hydraulic tunnel in the operation period, using Mohr-Coulomb and Hoek-Brown failure criteria, the minimum overburden thickness of circular hydraulic tunnel in infinite homogeneous body with or without lining was analyzed by elasto-plastic mechanics. The results were compared with those of Tresca criterion. The results show that when there is no lining, the minimum cover thickness calculated by Mohr-Coulomb criterion and Tresca criterion gradually decreases with the increase of cohesion. The results calculated by the Mohr-Coulomb criterion gradually decrease with the increase of internal friction Angle. When the rock hardness is the same, the calculated results by Hoek-Brown criterion decrease with the increase of GSI value. When there is a lining, when the elastic-plastic interface is inside the lining, the minimum cover thickness increases with the increase of the cohesion of the lining, and decreases with the increase of the internal friction Angle of the lining. When the elasto-plastic interface is located in the rock mass, the minimum overburden thickness decreases with the increase of the cohesion between the rock mass and the lining, and increases with the increase of the internal friction angle of the surrounding rock, while decreases with the increase of the internal friction Angle of the lining.