摘要
针对宝兰线大断面高含水率黄土隧道施工,通过对不同埋深及不同含水率情况下的进尺、开挖步序、核心土长度、竖撑形式、封闭距离等工况进行数值计算。通过变形结果对比分析可知:在黄土隧道中,随着开挖进尺长度的增加,拱顶及拱脚沉降量也相应增大;但增加的幅度有限。低含水率下的开挖变形受进尺影响较高含水率更为明显。核心土对控制变形非常明显,在高含水率中效果更为明显。核心土长度为5 m时,对沉降控制最为有利,能够减小沉降10%~20%;其中含水率越高越明显。核心土长度大于5 m后,对控制变形的作用将减小。竖撑形式对沉降的控制作用与埋深关系不大,竖撑减小沉降的作用随着含水率的增加更为明显。仰拱封闭距离对沉降影响非常大,随着仰拱封闭距离的增加,沉降量显著增大。对于黄土隧道,尤其是高含水率的黄土隧道,早封闭对控制沉降变形极为有利。
Aiming at the construction of loess tunnel with large cross-section and high water content in Baoji-Lanzhou PDL,the numerical calculation was carried out through the excavation lengths,excavation steps,core soil lengths,vertical support forms,closed distances under the conditions of different depths and water contents.It is known by comparative analysis on deformation results that:in a loess tunnel,the settlement amount of vault and arch springing increases with rising of excavation length,but its increasing range is limited.The excavation length has more obvious impacts on excavation deformation under low water content than under high water content;the effects of core soil to control deformation is quite evident and it becomes more obvious under high water content;when the length of core soil is5m,it is optimal to control the settlement and it can reduce the settlement up to10%~20%;the higher the water content is,the more significant the settlement control is;when the length of core soil is greater than5m,its effects to control deformation will be reduced;the controlling effects of vertical support on settlement is not related to the depth but the reducing effects of vertical support on settlement become more obvious with increasing of water content;the impacts of closed distance of inverted arch on settlement is very large and the settlement increases with rising of closed distance of inverted arch.In conclusion,early-closed of inverted arch is extremely favorable to control settlement deformation for the loess tunnel,especially for the loess tunnel with high water content.
作者
刘志强
宋冶
吴剑
王新东
Liu Zhiqiang;Song Ye;Wu Jian;Wang Xindong(China Railway Southwest Research Institute Co.,Ltd., Chengdu 611731 P.R.China;The First Survey and Design Institute of China Railway , Xi'an 710043, P.R.China)
出处
《科学技术与工程》
北大核心
2017年第33期334-339,共6页
Science Technology and Engineering
基金
中国中铁科学研究院有限公司青年基金(2015-KJ021-Z021-02)资助
关键词
黄土隧道
宝兰客专
高含水率
变形
基准值
loess tunnel
baoji-lanzhou passenger dedicated line
high water content
deformation
criteria
