汾河漫滩地层盾构隧道开挖面最小极限支护压力的研究
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摘要
针对河漫滩地质条件,运用数值分析方法,研究了欠压条件下分段推进盾构开挖面的稳定性。在考虑渗流的影响下,分析研究了不同埋深条件下的最小极限支护压力变化规律。结果表明:随着支护压力比的逐渐减小,隧道开挖面中心位移、塑性区、横向沉降、纵向沉降都要经历不敏感、较敏感和突变3个阶段;开挖面支护压力主要平衡的是地下水压力,水的影响不可忽视;在太原地铁2号线所考虑的区间,若最小极限支护压力比保持λ>0.4,开挖面前方则不会出现失稳状况;埋深对于最小极限支护压力比的影响不大。
Aiming at the geological conditions of floodplain,the stability of shield excavation surface with sublevel propulsion under the condition of underpressure was studied by using numerical analysis method.Considering the influence of seepage,the variation laws of the minimum limit support pressure under different buried depths were studied.The results showed that as the support pressure ratio gradually decreased,the center displacement,plastic zone,transverse settlement and longitudinal settlement of tunnel surface would undergo three stages of insensitivity,sensitivity and catastrophe.The main balance of support pressure on excavation surface was groundwater pressure,and the influence of water cannot be ignored.In the section of Taiyuan metro line 2,if the minimum limit support pressure was kept to be more than 0.4,the instability would not occur in front of the excavation surface,and the buried depth had little effect on the minimum limit support pressure ratio.
Aiming at the geological conditions of floodplain,the stability of shield excavation surface with sublevel propulsion under the condition of underpressure was studied by using numerical analysis method.Considering the influence of seepage,the variation laws of the minimum limit support pressure under different buried depths were studied.The results showed that as the support pressure ratio gradually decreased,the center displacement,plastic zone,transverse settlement and longitudinal settlement of tunnel surface would undergo three stages of insensitivity,sensitivity and catastrophe.The main balance of support pressure on excavation surface was groundwater pressure,and the influence of water cannot be ignored.In the section of Taiyuan metro line 2,if the minimum limit support pressure was kept to be more than 0.4,the instability would not occur in front of the excavation surface,and the buried depth had little effect on the minimum limit support pressure ratio.
引文
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[2]吕玺琳,周维祥,黄茂松.盾构隧道开挖面破坏模式及支护压力数值模拟[C]//第十一届全国土力学及岩土工程学术会议论文集.上海:同济大学,2011:1500-1504.
[3]秦建设.盾构隧道施工中开挖面失稳事故分析[J].浙江建筑,2005(S1):59-61+65.
[4]Horn M.Horizontal earth pressure on perpendicular tunnel face[C]//Proceedings of the Hungarian National Conference of the Foundation Engineer Industry.Hungarian:Budapest,1961.
[5]Leca E,Dormieux L.Upper and lower bound solutions for the face stability of shallow oircular tunnels infrictional material[J].Geotechnique,1990,40(4):581-606.
[6]黄正荣,朱伟,梁精华,秦建设.盾构法隧道开挖面极限支护压力研究[J].土木工程学报,2006(10):112-116.
[7]秦建设.黏土中盾构开挖面变形与破坏数值模拟研究[C]//中国力学会岩土力学专业委员会.第九届全国岩土力学数值分析与解析方法讨论会论文集.中国力学会岩土力学专业委员会,2007:5.
[8]乔金丽,张义同,高健.考虑渗流的多层土盾构隧道开挖面稳定性分析[J].岩土力学,2010,31(5):1497-1502.
[9]付亚雄,郑宏.软黏土地层顶管隧道开挖面稳定性数值研究[J].地下空间与工程学报,2017,13(S2):623-632.
[10]任建喜,张引合,冯超.地铁隧道盾构施工引起的古城墙变形规律及其控制技术[J].岩土力学,2011,32(S1):445-450.
[11]秦建设.盾构施工开挖面变形与破坏机理研究[D].南京:河海大学,2005.
[12]方勇,何川.土压平衡式盾构掘削面支护压力特性分析[J].岩土力学,2009,30(11):3528-3532.
[13]Ahmed M,Iskander M.Evaluation of tunnel face stability by transparent soil models[J].Tunnelling&Underground Space Technology Incorporating Trenchless Technology Research,2015,27(1):101-11.