辉绿岩脉引起的隧道大变形及其形成机制

Large Tunnel Deformation Caused by Diabase Dike and Its Formation Mechanism

研究目的:以龙厦铁路吴坑隧道为例,在辉绿岩工程性质分析的基础上,结合现场监测资料对辉绿岩脉分布段围岩压力、隧道变形的特点及隧道大变形的形成机制进行研究,为辉绿岩分布地区隧道设计、施工提供指导。研究结论:(1)辉绿岩富含高岭石,具有强度低、易崩解和弱膨胀的工程特性,在卸荷应力路径下,沿卸荷方向有强烈的扩容现象;(2)辉绿岩脉的分布对围岩压力的大小及分布有十分明显的影响,岩脉出露多的断面围岩压力明显比出露少的断面大,局部出露部位比邻近未出露部位的大;(3)辉绿岩脉的分布对隧道变形也有明显影响,拱顶出露岩脉的断面拱顶下沉量较大,边墙、拱腰出露岩脉多的断面,边墙收敛变形较大,岩脉出露多的区段,隧道变形时间较长;(4)辉绿岩脉分布段隧道大变形既有膨胀变形又有挤压变形;(5)本文研究成果可用于辉绿岩分布地区隧道的设计和施工。

Research purposes： Taking the Wukeng Tunnel of the Longyan - Xiamen Railway as an example, basing on the analysis of the engineering properties of the diabase and the on - site monitored data, this paper studies the pressure of the surrounding rock in the section of the diabase dikes, the deformation characteristics of the tunnel and the formation mechanism that causes the large tunnel deformation to provide the guidance for the design and construction of the similar tunnels. Research conclusions： （1） The diabase is rich in kaolinite, with the engineering properties of low strength, easy disintegration and weak expansion, but it is dilatable along the unloading direction under the unloaded stress path. （2） The distribution of the diabase dikes has the significant effect on the magnitude and distribution of the rock pressure. The pressure of the surrounding rock with exposing more diabase section is bigger than that with exposing less diabase section, and the pressure of the exposing part is bigger than that of the adjacent parts without exposure. （3） The distribution of diabase dikes also affect the tunnel deformation significantly. The settlement of the vault with exposing the section is larger. In the section of exposing the diabase on the dome, the convergence deformation of the sidewall is larger. In the section of exposing the diabase on the sidewall and arch, the tunnel deformation lasts longer. （4） In the section of exposing more diabase, the large tunnel deformation contains the swelling deformation and compressional deformation. （5） This research result can be available for the design and construction of tunnel in diabase zone.