不同的开挖方式对公路隧道围岩稳定性影响分析——以重庆公路隧道为例
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摘要
以重庆某高速公路隧道为研究对象,采用ANSYS有限元软件分析了台阶法和全断面开挖法两种开挖方式对高速公路隧道围岩稳定性的影响。研究表明,重庆某高速公路隧道的围岩是以页岩、泥岩和泥质砂岩等多种围岩材质共同构成的一个高速公路的地段,而其中对于围岩的分类主要是可以分为Ⅲ、Ⅳ、Ⅴ这3类围岩,但是其中最能代表整个围岩路段的是IV类围岩。把该高速公路隧道的挖掘方式进行比较分析时,发现使用上下台阶正断面的挖掘方法可以最大程度地减少隧道围岩所移动的位移距离;进行施工前期支护时,对于隧道围岩的移动位移可以进行控制和制止,这样在进行隧道施工作业时稳定性得到保证。通过应力场对比,采用上下台阶正断面方式时,隧道围岩在整个开挖过程受到的扰动要小于全断面方式。在隧道各部位具有较小的塑性区范围应力集中。在初期支护施加后,可较好地改善应力集中现象。
A highway tunnel in Chongqing is taken as the research object,and the influence of two excavation methods,step excavation method and full-face excavation method,on the stability of surrounding rock of highway tunnel is analyzed by ANSYS finite element software. The study shows that the surrounding rocks of a Expressway Tunnel in Chongqing are mainly shale,mudstone and argillaceous sandstone. The types of surrounding rocks include Class Ⅲ、Ⅳ and Ⅴ,of which the representative is Class Ⅳ. By comparing and analyzing the displacement field of the two excavation methods,it is found that the displacement of the surrounding rock of the tunnel is relatively small when the normal section of the upper and lower steps are adopted. After the initial support is applied,the displacement can be effectively controlled,so that the stability of the tunnel construction can be guaranteed. By comparing the stress field,the disturbance of tunnel surrounding rock in the whole excavation process is less than that in the full-face excavation when the normal section of the upper and lower steps is adopted. There are smaller plastic zones and stress concentrations in all parts of the tunnel. After initial support is applied,the stress concentration phenomenon can be better improved.
A highway tunnel in Chongqing is taken as the research object,and the influence of two excavation methods,step excavation method and full-face excavation method,on the stability of surrounding rock of highway tunnel is analyzed by ANSYS finite element software. The study shows that the surrounding rocks of a Expressway Tunnel in Chongqing are mainly shale,mudstone and argillaceous sandstone. The types of surrounding rocks include Class Ⅲ、Ⅳ and Ⅴ,of which the representative is Class Ⅳ. By comparing and analyzing the displacement field of the two excavation methods,it is found that the displacement of the surrounding rock of the tunnel is relatively small when the normal section of the upper and lower steps are adopted. After the initial support is applied,the displacement can be effectively controlled,so that the stability of the tunnel construction can be guaranteed. By comparing the stress field,the disturbance of tunnel surrounding rock in the whole excavation process is less than that in the full-face excavation when the normal section of the upper and lower steps is adopted. There are smaller plastic zones and stress concentrations in all parts of the tunnel. After initial support is applied,the stress concentration phenomenon can be better improved.
引文
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[2]周连伟,赵杰,姚晨晨.深埋公路隧道围岩稳定性中强度折减法的应用[J].辽宁工程技术大学学报(自然科学版),2016,35(11):1272-1278.
[3]苏永华,何新亮,罗正东.基于强度折减法的隧道围岩稳定性研究[J].水文地质工程地质,2014,41(41):48-54.
[4]陈真才.软弱围岩大断面隧道结构稳定性丏究[D].西安:西安工业大学,2016.
[5]邓祥辉.大断面软弱围岩隧道洞口段施工工法比较分析[J].西安工业大学学报,2013,33(12):974-980.
[6]陈立平,张顶立,房倩,等.一种基于数值应力场的强度各向异性边坡稳定性分析方法[J].岩土力学,2014,35(12):3611-3618.
[7]张健.戚家垭隧道围岩位移监测及稳定性分析[D].北京:中国地质大学,2014.
[8]张畳辉,郭吉平,孔凡林.基于块体理论的隧道围岩稳定性分析[J].隧道建设,2015,35(1):41-45.
[9]潘广录.公路隧道围岩稳定性分析与支护[J].山西建筑,2014,40(8):197-198.
[10]许宇明.应变软化对深部隧道围岩多层断裂的影响研究[J].湖南通科技,2016,42(3):172-176,214.
[11]谢俊杰,毛琼柳,凌同华,等.断层对小净距隧道稳定性的影响[J].交通科学与工程,2016,32(1):67-71.