崤山隧道异常水平变形段支护结构优化探讨

Optimization discussion of support structure for abnormal horizontal deformation section of Xiaoshan tunnel

在双洞双线深埋崤山特长铁路隧道施工中,部分区段出现水平收敛变形过大而引起初支边墙发生大范围开裂和严重鼓出,直接影响隧道施工安全和隧道结构承载力。采用理论分析、现场监测和数值模拟方法,在重点探讨隧道异常水平变形原因基础上,开展优化初支边墙曲率、厚度及增设锚杆等措施对控制初支水平变形效果的参数分析,总结不同措施下初支变形规律,进而提出支护结构设计优化参数,工程应用验证了优化措施控制变形的效果。研究结果表明:隧道初支异常水平变形及边墙开裂的主因是该区段水平围岩压力较大,而马蹄形断面型式和原设计支护参数条件下初支无法有效抵抗较大水平侧压力;通过增大边墙曲率可改善初支受力状态,进而有效约束水平变形;增加初支厚度和增设锚杆措施也可减小收敛变形,但效能有限。研究成果可为后续区段的设计施工提供参考,也可为类似工程所借鉴。

In the construction of Xiaoshan extra-long tunnel,the oversize of horizontal convergences leads to primary support damage such as crack and swelling and bring hidden troubles to tunnel structure and construction.This paper mainly analyzed the reason of abnormal horizontal deformation,and discussed the support structure optimization on the aspects of side wall curvature,thickness of primary support and setting anchors by methods of numerical simulation and monitoring measurement.The result shows that the main reason for the abnormal horizontal deformation is that the horizontal lateral pressure in the corresponding section is larger,while the original thin section type and the weak support parameters are not compatible with the larger horizontal lateral pressure.The increase of the side wall curvature could improve the stress states of the support structure and effectively control the abnormal horizontal deformation.Increasing the thickness of structure and setting anchor can also reduce the deformation,but the efficiency of restraining the deformation is limited.The measure of increasing the side wall curvature is the necessary and effective way to restrain the abnormal horizontal deformation.In order to cope with the abnormal deformation problem,the design alteration adopted in the corresponding section of Xiaoshan tunnel has certain effect,but it can be further optimized.The research results in this paper can provide reference for the design and construction of subsequent sections,and can also be used for reference by similar engineering.