引水沟渠冻结法施工中的温度场、冻结壁演变和开挖稳定性分析

Study on Temperature Field,Frozen Wall Evolution and Excavation Stability Analysis of Freeze Construction of Diversion Tunnel

为准确计算冻结壁厚度、了解开挖引水沟渠对地层稳定性的影响,从而确保工程的安全稳定性,结合工程实例,根据冻土的热物理参数及力学性质,运用解析方程和经验公式分别计算了引水沟渠冻结法施工的冻结壁厚,并对比计算结果与现场实测温度反推出的冻结壁厚度,同时利用多物理场耦合软件模拟冻结壁的形成及开挖后的受力变形,分析了引水沟渠在冻结暗挖过程中冻结壁的安全稳定性。结果表明,理论计算中拉麦公式考虑的因素少,计算结果偏大,维亚洛夫公式设计冻结壁厚度相对合理;数值模拟可得出引水沟渠周围土体的应力场、位移场分布,可验证施工方案的合理性;在实际工程中可结合经验估算、现场实测理论计算与数值模拟计算来最终确定设计方案。

For the accurately calculating the thickness of frozen wall of the diversion ditch and understanding the im- pact on the stability of the excavation of the diversion ditch as well as ensuring the safety and stability of the project, based on the project instance, analytic and empirical equations are used to calculate the thickness of frozen wall of the di- version ditches in freezing construction method. And then the calculation results are compared with the estimation value obtained by the measured temperature. The safety and stability of the frozen wall are analyzed in the freezing excavation process of diversion ditches by using multi-physical coupling software to simulate the formation of frozen wall and deform- ation of frozen wall after excavation. The results show that less factors considered in the formula of Lame. So, the calcu- lation results are relatively large. The thickness of frozen wall with vianov formula is relatively reasonable. The stress field, displacement field distribution around the diversion ditch can be obtained with the numerical simulation, which can verify the rationality of construction scheme. The empirical estimation, calculation of field theory and numerical simula- tion can be combined to determine the final design scheme in practical engineering.