浅埋偏压隧道洞口段初期支护变形分析与控制

Analysis and Control of Primary Support Deformation for the Entrance of a Shallow Tunnel under Unsymmetrical Pressure

以某在建山岭隧道为工程背景,分析了洞口段初期支护产生过大变形的原因,采用有限元软件对其开挖施工过程进行了仿真分析,结合现场监测结果,得到了浅埋偏压隧道洞口段初期支护的受力及变形状况,并提出了变形控制措施。分析结果表明:洞口偏压段初期支护呈现明显的不对称弯曲变形;最大拉应力出现在深埋侧拱腰内边缘,最大压应力出现在深埋侧的拱脚外边缘和浅埋侧的拱腰内边缘;通过有序减压卸载、增设临时斜撑、洞内注浆、及时成环等措施可有效控制变形发展。研究结果可为类似地质地形条件下隧道洞口段初期支护的设计与施工提供参考。

Based on an tunnel project under construction, the cause of great deformation of primary support in the shallow tunnel entrance under unsymmetrical pressure is analyzed, the stress and deformation of primary support are obtained by establishing the FEM calculation model and monitoring measurement. Then, the deformation control measures are put forward. The results show that： the bending deformation of the primary support in biased pressure section of entrance is asymmetric, the maximum tensile stress appears at the interior boundary of the arch haunch in deeper buried side while the maximum compressive stress appears at the outer edge of arch feet in deeper buried side and the interior boundary of arch haunch in shallow buried side; The deformation can be controlled by reducing pressure orderly, adding temporary slant support, grouting into rock, making support circularity timely and so on. The result can provide reference for the design and construction of the tunnel in the similar geological conditions.