极端降雨对黄土沟壑区隧洞施工力学效应影响分析  

Analysis of Mechanical Effects of Extreme Rainfall on Tunnel Construction in Loess Gully Area

作　　者：尚凯 陶虎[1] 方自刚 樊娜娜 万宇 SHANG Kai;TAO Hu;FANG Zi-gang;FAN Na-na;WAN Yu(School of Civil Engineering,Lanzhou Jiaotong University,Lanzhou 730070,China)

机构地区：[1]兰州交通大学土木工程学院,兰州730070

出　　处：《科学技术与工程》2024年第15期6388-6397,共10页Science Technology and Engineering

基　　金：国家自然科学基金(52360031);技术创新引导计划-科技专员专项(23CXGA0074);甘肃省高等学校产业支撑计划(2022CYZC-32)。

摘　　要：黄土地区输水隧洞的建设中,降雨入渗极大影响着输水隧洞围岩稳定性。利用非饱和渗流理论和数值模拟方法研究了极端降雨条件入渗与黄土沟壑区隧洞的开挖扰动耦合影响下围岩的变形和渗流场演变规律,通过Plaxis3D模型对降雨入渗下新奥法施工过程中围岩力学特性、初期支护过程进行流固耦合分析。结果显示,降雨等级越高,围岩孔隙水压力变化幅度越大,对围岩的稳定性越不利;降雨入渗与开挖扰动会加速土层中渗流场和应力场的重分布过程;基于沟道的汇水特性,隧洞围岩含水率在最初5~10 d呈台阶式增长,拱顶、拱腰和拱趾处的最大变形为17.8、28.2、24.6 mm,最大剪切应力为150.6、182.5、175.3 kPa,降雨结束约15~20 d围岩变形速率逐渐减小收敛至特定值,但围岩的应力持续增加,为避免围岩发生塑性变形,故可在15~20 d进行二次衬砌支护。本次研究结果可对极端降雨期黄土沟壑地区隧洞施工安全控制提供参考。Rainfall infiltration greatly affects the stability of the surrounding rock in the construction of water tunnels in loess areas.The unsaturated seepage theory and numerical simulation method were used to study the deformation and seepage field evolution of the surrounding rock under the coupling influence of extreme rainfall infiltration and the excavation disturbance of loess gully area tunnel,and the coupled flow-solidity analysis was carried out through the Plaxis3D model to analyze the mechanical properties of the surrounding rock and the initial support process in the construction of Xin ao method under rainfall infiltration.The results show that the higher the rainfall level is,the larger the pore water pressure change of the surrounding rock is,and the more unfavorable it is to the stability of the surrounding rock,rainfall infiltration and excavation disturbance will accelerate the redistribution process of seepage and stress fields in the soil layer.Based on the catchment characteristics of the trench,the water content of the surrounding rock of the tunnel shows a stepwise increase in the first 5~10 d,and the maximum deformations at the top of the arch,the waist of the arch,and the toe of the arch are 17.8 mm,28.2 mm,and 24.6 mm,with maximum shear deformations at the top,waist,and toe of the arch,24.6 mm,the maximum shear stress is 150.6 kPa,182.5 kPa,175.3 kPa,rainfall end about 15~20 d perimeter rock deformation rate gradually reduce convergence to a specific value,but the stress of the perimeter rock continues to increase,in order to avoid plastic deformation of the perimeter rock,so can be carried out in the 15~20 d of the second lining support.The results of this study can provide reference for the safety control of tunnel construction in loess gully area during extreme rainfall.

关 键 词：极端降雨 黄土沟壑区 隧洞开挖 力学响应 时效性 

分 类 号：TU457[建筑科学—岩土工程] TV139.14[建筑科学—土工工程]