黄土隧道围岩压力拱效应分析

发布时间：2019-06-06 03:00

【摘要】：以兰渝铁路大断面黄土隧道工程为背景,采用数值计算和模型试验对黄土围岩压力拱效应进行分析,可得结论:(1)由于荷载传递路线发生偏转,拱部围岩切向应力因承担径向传来的荷载而增加,且离隧道边界越近应力增幅越大,压力拱边界向围岩深部扩展。(2)靠近隧道洞周,边墙处应力路径切向应力、径向应力低于原岩应力,切向应力表现出较强的应力集中,径向应力只有小幅增加。(3)相对于黏性土,黄土抗剪强度较小,需要更大范围的土体参与承受围岩压力,致使压力拱外边界远离隧道断面;黄土围岩压力拱边墙处最大,拱顶处次之,拱底处最小。(4)黄土围岩破坏过程表现为局部裂隙产生、局部裂隙扩展、裂隙急剧贯通、残余强度等4个阶段;拱顶松动塌落出现在边墙剪切滑移破坏基础上。(5)数值分析与模型试验所得黄土围岩压力拱的范围基本相符,验证了压力拱的客观存在;压力拱承担着自重与外部土体荷载,自洞周向围岩深部依次为松动区、压力拱、原岩应力区。
[Abstract]:Based on the large section loess tunnel project of Lanzhou-Chongqing Railway, the pressure arch effect of loess surrounding rock is analyzed by numerical calculation and model test. The conclusions are as follows: (1) due to the deflection of load transfer route, The tangential stress of the surrounding rock of the arch increases due to the load coming from the radial direction, and the closer the stress is to the tunnel boundary, the greater the stress increases, and the pressure arch boundary extends to the deep part of the surrounding rock. (2) near the tunnel circumference, the tangential stress of the stress path at the side wall, The radial stress is lower than the original rock stress, the tangential stress shows a strong stress concentration, and the radial stress only increases slightly. (3) compared with the clay soil, the shear strength of loess is smaller, so it is necessary for the soil to participate in the surrounding rock pressure. The outer boundary of the pressure arch is far away from the tunnel section. The pressure arch side wall of loess surrounding rock is the largest, the arch roof is the second, and the arch bottom is the smallest. (4) the failure process of loess surrounding rock is the formation of local cracks, the propagation of local cracks, the sharp penetration of cracks and the residual strength. The loose collapse of arch roof appears on the basis of shear slip failure of side wall. (5) the numerical analysis is basically consistent with the range of pressure arch of loess surrounding rock obtained by model test, and the objective existence of pressure arch is verified. The pressure arch bears the load of self-weight and external soil, and the loosening area, the pressure arch and the original rock stress area are in turn from the tunnel to the deep of the surrounding rock.
【作者单位】：北京城建设计研究总院有限责任公司;
【基金】：铁道部科技研究开发计划重大项目(2009G005) 国家杰出青年科学基金(51108020)
【分类号】：U451.2

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