坑中坑开挖影响下的基坑稳定性研究
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摘要
坑中坑开挖对于悬臂式支护结构基坑稳定系统有诸多影响,内坑的开挖会引起基坑被动区土体抗力损失,增大坑外土体的剪切变形趋势,降低基坑整体稳定性。采用强度折减有限元法,对坑中坑的三个主要影响因素:坑址系数、深度比、面积比进行了控制变量研究,研究表明:对比三种失稳判据下的稳定安全系数,基坑整体稳定安全系数与坑趾系数呈正相关关系,与深度比和面积比呈负相关关系,据此建议在内坑开挖过程中,要尽量避免内坑紧邻外坑坑壁开挖、内坑过度深挖、内坑面积过大开挖。
Pit in pit excavation has many effects to the cantilever retaining structure foundation pit's stability system. Pit in pit excavation will cause the loss of soil's resistance in passive zone, and increase the trend of soil's shear deformation, at the same time reduce the overall stability of foundation pit. In this paper, by using strength reduction finite element method, three main factors of pit in pit pit site coefficient, depth ratio, area ratio were analyzed. Research results shows that: comparing the stability safety factor under three kinds of instability criterion, this paper suggests using the run through of plastic zone optimization criterion. The stability safety factor of foundation pit is positively related to pit toe coefficient, and is negatively related to the depth ratio and area ratio. Therefore, in the process of pit excavation, pit in pit's excavation being adjacent to the outer wall, excessive digging and the size being too large should be avoided.
Pit in pit excavation has many effects to the cantilever retaining structure foundation pit's stability system. Pit in pit excavation will cause the loss of soil's resistance in passive zone, and increase the trend of soil's shear deformation, at the same time reduce the overall stability of foundation pit. In this paper, by using strength reduction finite element method, three main factors of pit in pit pit site coefficient, depth ratio, area ratio were analyzed. Research results shows that: comparing the stability safety factor under three kinds of instability criterion, this paper suggests using the run through of plastic zone optimization criterion. The stability safety factor of foundation pit is positively related to pit toe coefficient, and is negatively related to the depth ratio and area ratio. Therefore, in the process of pit excavation, pit in pit's excavation being adjacent to the outer wall, excessive digging and the size being too large should be avoided.
引文
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[13]李垠,苏凯,李杰.Mohr-Coulomb等面积圆屈服准则在边坡稳定分析中的应用[J].大地测量与地球动力学,2009,29(1):135-139.
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[16]栾茂田,武亚军,年延凯.强度折减有限元法中边坡失稳的塑性区判据及其应用[J].防灾减灾工程学报,2003,23(3):1-8.
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[2]陈乐意,李镜培,梁发云,等.坑中坑对基坑围护结构水平位移影响数值分析[J].岩土工程学报,2008,30(S1):59-61.
[3]徐意智,廖少明,周小华,等.上海软土坑中坑型基坑围护的等效深度计算法[J].岩土力学,2012,33(9):2736-2742.
[4]徐飞飞,崔梓萍,徐意智,等.坑中坑的基坑变形分布及其变化规律[J].地下空间与工程学报,2012,8(S1):1376-1380.
[5]裴利剑,屈本宁,钱闪光.有限元强度折减法边坡失稳判据的统一性[J].岩土力学,2010,31(10):3337-3341.
[6]李永亮,周国胜,李永鹏.有限元强度折减法边坡失稳判据的适用性研究[J].水利与建筑工程学报,2018,16(5):125-129.
[7]杨才,王世君,丰土根.基于塑性区开展的边坡失稳判据研究[J].中国科技论文,2016(11):1461-1464.
[8]李博,王洪滨,姜彤,等.基于PIV技术的静压桩沉桩过程中桩周粉土位移场的试验研究[J].华北水利水电大学学报(自然科学版),2018,39(1):91-96.
[9]费康,张建伟.ABAQUS在岩土工程中的应用[M].北京:中国水利水电出版社,2010:391-411.
[10]朱向荣,王金昌.ABAQUS软件中部分土模型简介及其工程应用[J].岩土力学,2004,25(S2):144-148.
[11]申明亮,廖少明,周小华,等.坑中坑基坑应力场的参数化分析[J].岩土工程学报,2010,32(S2):187-191.
[12]申明亮,廖少明,邵伟.考虑内坑影响的坑中坑基坑被动土压力叠加算法[J].上海交通大学学报,2012,46(1):79-83.
[13]李垠,苏凯,李杰.Mohr-Coulomb等面积圆屈服准则在边坡稳定分析中的应用[J].大地测量与地球动力学,2009,29(1):135-139.
[14]丰土根,熊中华,余波.坑中坑开挖对悬臂式支护结构侧移的影响分析[J].岩土工程学报,2013,35(11):2053-2058.
[15]宋二祥.土工结构安全系数的有限元计算[J].岩土工程学报,1997,19(2):1-7.
[16]栾茂田,武亚军,年延凯.强度折减有限元法中边坡失稳的塑性区判据及其应用[J].防灾减灾工程学报,2003,23(3):1-8.
[17]沈玉涛.软土地区深大基坑分区开挖力学效应数值模拟[J].水利与建筑工程学报,2017,15(6):23-27.