新建黄土隧道开挖及支护对既有隧道影响的数值模拟分析
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摘要
新建隧道临近既有隧道时,隧道施工会引起围岩的应力重分布,从而对既有隧道产生影响。为了研究新建隧道施工对既有隧道的影响,以黄土地区某隧道工程为依托,利用有限元软件,通过数值模拟计算,分析开挖方法及支护措施对既有隧道最终位移场、应力场分布及围岩塑性区演化的影响,得出如下结论:采用台阶法时会对既有隧道产生扰动,引起既有两隧道的最大位移分别为0. 97 mm和2. 56 mm,均出现在拱顶处,总体位移较小;采用3种不同的支护措施时,最大应力均出现在距离最近既有隧道的仰拱处(不超过600kPa);塑性区主要分布在最近既有隧道的仰拱处,但不会引起塑性破坏;3种支护方案对应的整体模型最大总位移分别为80. 3 mm、77. 8 mm和89. 2 mm,管棚超前支护对变形控制效果明显。
When a new tunnel is constructed near an existing tunnel,because of the fact that the construction of the tunnel will cause the stress redistribution of surrounding rock, the new tunnel will have an impact on the existing tunnel. A new tunnel near the existing tunnel in loess area is used as an example in this paper. In order to reduce the impact of the construction of the new tunnel on the existing tunnel,by using finite element software,the final displacement field,stress field distribution law and plastic zone evolution law of surrounding rock of existing tunnels are simulated by different excavation methods and supporting measures. The conclusions are drawn as follows:when bench method is adopted in the construction of a tunnel,disturbance will occur to existing tunnels,resulting in the maximum displacement of existing two tunnels being 0. 97 mm and 2. 56 mm,respectively,both of which appear at the vault top with the overall displacement being a small value; when three different supporting measures are adopted,the maximum stress will all appear at the inverted arch of the nearest existing tunnel,the maximum of which is less than 600 kPa; the plastic zone mainly distributes at the inverted arch of the nearest existing tunnel,but it will not cause plastic damage; the maximum total displacement of the whole model corresponding to the three supporting schemes is 80. 3 mm,77. 8 mm and 89. 2 mm,respectively,which shows that the effect of pipe shed advanced support on deformation control is effective; if the construction of pipe shed is difficult,then the isolation pile will be used together as a protection method.
When a new tunnel is constructed near an existing tunnel,because of the fact that the construction of the tunnel will cause the stress redistribution of surrounding rock, the new tunnel will have an impact on the existing tunnel. A new tunnel near the existing tunnel in loess area is used as an example in this paper. In order to reduce the impact of the construction of the new tunnel on the existing tunnel,by using finite element software,the final displacement field,stress field distribution law and plastic zone evolution law of surrounding rock of existing tunnels are simulated by different excavation methods and supporting measures. The conclusions are drawn as follows:when bench method is adopted in the construction of a tunnel,disturbance will occur to existing tunnels,resulting in the maximum displacement of existing two tunnels being 0. 97 mm and 2. 56 mm,respectively,both of which appear at the vault top with the overall displacement being a small value; when three different supporting measures are adopted,the maximum stress will all appear at the inverted arch of the nearest existing tunnel,the maximum of which is less than 600 kPa; the plastic zone mainly distributes at the inverted arch of the nearest existing tunnel,but it will not cause plastic damage; the maximum total displacement of the whole model corresponding to the three supporting schemes is 80. 3 mm,77. 8 mm and 89. 2 mm,respectively,which shows that the effect of pipe shed advanced support on deformation control is effective; if the construction of pipe shed is difficult,then the isolation pile will be used together as a protection method.
引文
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[2]周杰,罗军镪,杨凡杰,等.安家庄隧道施工对相邻已营运隧道安全性的评估[J].土工基础,2018,32(2):146-150.
[3]王起才,赵侃,展宏跃.新建隧道施工对临近既有隧道结构安全性影响分析[J].铁道建筑技术,2010(3):83-86.
[4]王清标,蒋金泉,路林海,等.不同开挖方式对近距离交叠隧道影响模拟研究[J].岩石力学与工程学报,2013,32(10):2079-2087.
[5]包德勇.近距离交叠隧道施工影响的数值模拟[J].地下空间与工程学报,2011,7(1):127-132,206.
[6]刘镇,房明,周翠英,等.交叉隧道施工中新建隧道周围复合地层与间距对既有隧道的沉降影响研究[J].工程地质学报,2010,18(5):736-741.
[7]罗勇.数值分析结合自动化监测技术在地铁下穿工程中的应用[J].铁道标准设计,2019(3):119-125.
[8]杨永波,刘明贵,张国华,等.邻近既有隧道的新建大断面隧道施工参数优化分析[J].岩土力学,2010,31(4):1217-1226.
[9]王剑晨,张顶立,张成平,等.北京地区浅埋暗挖法下穿施工既有隧道变形特点及预测[J].岩石力学与工程学报,2014,33(5):947-956.
[10]黄德中,马险峰,吴俊淞,等.软土地区盾构上穿既有隧道的离心模拟研究[J].岩土工程学报,2012,34(3):520.
[11]李磊,张孟喜,吴惠明,等.近距离多线叠交盾构施工对既有隧道变形的影响研究[J].岩土工程学报,2014,36(6):1036-1043.
[12]李志业,曾艳华,等.地下结构设计原理与方法[M].成都:西南交通大学出版社,2003.
[13]曹海静,刘志强,吴剑,等.铁路黄土隧道施工变形规律及预留变形量研究[J].铁道标准设计,2018,62(3):85-89.
[14]李治.Midas/GTS在岩土工程中应用[M].北京:中国建筑工业出版社,2016.
[15]钱家欢,殷宗泽.土工原理与计算[M].北京:中国水利水电出版社,1996.
[16]杨成忠,罗坤,王威,等.隧道衬砌内部空洞探测的FDTD正演模拟与试验研究[J].铁道标准设计,2018,62(11):114-117,124.