降雨作用下浅埋隧道支护参数正交反演分析

Orthogonal Back-analysis of Surrounding Rock Support Parameters for Shallow Buried Tunnel under Rainfall

为了迅速、准确地评价隧道掌子面前方围岩的稳定性和判断围岩初期支护设计参数是否合理,结合浅埋暗挖土质隧道工程实践,根据现场围岩监控量测位移实测资料,采用正交优化试验法和边界单元正演反算分析方法,对降雨作用下隧道围岩初期支护设计参数的合理性做出判断,得到了较高的计算精度。研究表明,采用正交优化正算反分析边界单元法可以比较准确地反演出降雨作用下围岩-支护系统模型的等效弹性模量、侧压力系数和泊松比等参数及其变化,可以迅速地对隧道掌子面前方围岩的稳定性做出评价,并据此对围岩变形破坏模式进行预测。

In order to rapidly and accurately evaluate the frontage surrounding rock stability of tunnel face, and estimate whether the preliminary support design parameter of surrounding rock is reasonable, connected with the concrete engineering practice of shallow buried and blind excavated soil tunnel, adopting orthogonal optimum test methods and the back-analysis positively deducing one of boundary element method （BEM）, the rationality of preliminary support design parameter of surrounding rock under the action of rainfall was judged on the basis of the site - measured displacement data of surrounding rock monitored measurement, meanwhile the higher calculation precision was obtained. The research results show that not only the equivalent elastic modulus, coefficient of confinement pressure, and Poission ＇ s ratio of surrounding rock and support system model under rainfall may be more accurately back analyzed, but their change and the frontage surrounding rock stability of tunnel face may be rapidly and accurately evaluated too, by adopting the mentioned above orthogonal optimum and back-analysis BEM. Additionally, the deformation and failure pattern diagram of tunnel frontage surrounding rock may be forecasted, so that the construction can be promptly instructed, and irrational design parameters are modified.