Design and monitoring analysis of deep foundation pit of super-large subway station adjacent existing section tunnel
-
摘要: 宁波轨道交通7号线小洋江站为多线换乘地下三层车站,基坑长度270.8 m,四线段基坑宽度51.4~55.7 m,两线段基坑宽度19.6~27.3 m,基坑深度27~31 m。车站建设场地存在深厚软土,基坑北侧距已运营的区间隧道约30.8 m,基坑变形控制要求较高。为控制基坑与邻近区间隧道变形,基坑围护设计采用地连墙+内支撑体系,同时采用硬分坑分时分段施工、软分坑分层开挖、地连墙构造段加长切断承压水层及设置施工便道与栈桥等一系列措施。监测结果表明,基坑大阳角采用软分坑与分层开挖的方式,对其变形控制非常有效;地表沉降对于坑外荷载较为敏感,坑外存在长期荷载区域地表沉降远大于其余区域;基坑开挖对邻近区间隧道存在影响,开挖深度小于隧道埋深时,对区间隧道影响较大,而开挖深度超过隧道埋深时,对区间隧道影响相对较小,最终区间隧道沉降为5.9 mm,控制在允许范围内。Abstract: Xiaoyangjiang Station of Ningbo Rail Transit Line 7 is a multi-line transfer station with a three-storey underground. The length of the foundation pit is 270.8 m, the width of the foundation pit of the four line sections is 51.4~55.7 m, the width of the foundation pit of the two line sections is 19.6~27.3 m, and the depth of the foundation pit is 27~31 m. The station construction site is located in an area with deep soft soil and is 30.8 m away from the adjacent section tunnel, which has high requirements for foundation pit deformation control. To control the deformation of the foundation pit and the adjacent tunnel, the foundation pit support design adopts the diaphragm wall + internal support system, and adopts a series of measures such as hard pit time-sharing and section construction, soft pit layered excavation, lengthening the diaphragm wall structural section to cut off the confined water layer, and setting up construction access roads and trestles. The monitoring results show that the deformation control of the large external corner of the foundation pit is very effective by using soft pit division and layered excavation; The surface settlement is sensitive to the load outside the pit, and the surface settlement in the area with long-term load outside the pit is much larger than that in the other areas; The excavation of foundation pit has an impact on the adjacent section tunnel. When the excavation depth is less than the tunnel buried depth, the impact on the section tunnel is greater, while when the excavation depth exceeds the tunnel buried depth, the impact on the section tunnel is relatively small. The final settlement of the section tunnel is 5.9 mm, which is controlled within the allowable range.
-
表 1 土层物理力学性质参数
Table 1. Soil layer physical and mechanical parameters
土层编号 土层名称 含水率
w/%重度
γ /(kN·m−3)黏聚力
c/kPa内摩擦角
φ/(°)1-1a 杂填土 20.0 5 15 1-1b 素填土 36.9 18.4 10 9 1-2 黏土 35.3 18.7 26.0 13.2 1-3b 淤泥质黏土 48.0 17.4 13.3 8.3 2-1 黏土 42.1 17.8 16.0 9.7 2-2b 淤泥质黏土 51.2 17.1 13.4 8.3 2-2c 淤泥质粉质黏土 43.3 17.7 13.3 8.6 3-2 粉质黏土 34.1 18.6 15.1 9.1 4-1b 淤泥质粉质黏土 39.4 18.0 16.8 10.4 4-2a 黏土 39.5 18.0 19.5 11.5 6-3a 粉质黏土 28.8 19.2 27.5 14.3 6-4a 粉砂 22.2 20.2 3 30 6-4b 砾砂 20.5 2 35 7-1 粉质黏土 26.3 19.7 33.5 16.4 7-1t 中砂 26.6 19.7 2 33 8-3a 中砂 24.1 20.0 2 34 8-3b 砾砂 20.0 20.8 2 35 9-1a 粉质黏土 25.5 19.8 36.1 16.6 表 2 主要监测项目表
Table 2. Table of main monitoring items
监测项目 监测代码 控制值/mm 地连墙水平位移 CX 42.0(北基坑) 82.98(南基坑) 周边地表沉降 D 30.0(北基坑) 55.32(南基坑) 既有区间隧道沉降 S(环) 10 -
[1] 韩 晓. 上海紧邻地铁超大深基坑工程设计与实践[J]. 岩土工程技术, 2024, 38(1): 70-74. (HAN X. Design and practice of super-large deep foundation pit adjacent to subway in Shanghai[J]. Geotechnical Engineering Technique, 2024, 38(1): 70-74. (in Chinese) doi: 10.3969/j.issn.1007-2993.2024.01.012HAN X. Design and practice of super-large deep foundation pit adjacent to subway in Shanghai[J]. Geotechnical Engineering Technique, 2024, 38(1): 70-74. (in Chinese) doi: 10.3969/j.issn.1007-2993.2024.01.012 [2] 乔丽平, 李韵迪, 杨 超. 某邻地铁超大直径圆环撑软土深基坑变形特性分析[J]. 岩土工程技术, 2023, 37(1): 118-126. (QIAO L P, LI Y D, YANG C. Analysis on deformation characteristics of super large diameter ring bracing deep foundation pit in soft soil near subway[J]. Geotechnical Engineering Technique, 2023, 37(1): 118-126. (in Chinese) doi: 10.3969/j.issn.1007-2993.2023.01.021QIAO L P, LI Y D, YANG C. Analysis on deformation characteristics of super large diameter ring bracing deep foundation pit in soft soil near subway[J]. Geotechnical Engineering Technique, 2023, 37(1): 118-126. (in Chinese) doi: 10.3969/j.issn.1007-2993.2023.01.021 [3] 徐四一, 丁传松. 复杂条件下软土超深基坑变形特性分析[J]. 岩土工程技术, 2023, 37(6): 749-753. (XU S Y, DING C S. Analysis of deformation characteristics of super deep pit excavation in soft soil under complex conditions[J]. Geotechnical Engineering Technique, 2023, 37(6): 749-753. (in Chinese) doi: 10.3969/j.issn.1007-2993.2023.06.020XU S Y, DING C S. Analysis of deformation characteristics of super deep pit excavation in soft soil under complex conditions[J]. Geotechnical Engineering Technique, 2023, 37(6): 749-753. (in Chinese) doi: 10.3969/j.issn.1007-2993.2023.06.020 [4] 张 旭, 王杰杰. 深基坑施工对邻近既有地铁车站附属的影响分析[J]. 岩土工程技术, 2023, 37(4): 492-498. (ZHANG X, WANG J J. Impact analysis of foundation pit excavation near the existing metro station auxiliary structure[J]. Geotechnical Engineering Technique, 2023, 37(4): 492-498. (in Chinese) doi: 10.3969/j.issn.1007-2993.2023.04.021ZHANG X, WANG J J. Impact analysis of foundation pit excavation near the existing metro station auxiliary structure[J]. Geotechnical Engineering Technique, 2023, 37(4): 492-498. (in Chinese) doi: 10.3969/j.issn.1007-2993.2023.04.021 [5] 马庆迅, 张新涛, 刘云霞. 基坑开挖及建筑加载对紧邻地铁的影响分析[J]. 岩土工程技术, 2023, 37(3): 342-347. (MA Q X, ZHANG X T, LIU Y X. Influence of foundation pit excavation and building loading on nearby subway tunnel[J]. Geotechnical Engineering Technique, 2023, 37(3): 342-347. (in Chinese) doi: 10.3969/j.issn.1007-2993.2023.03.014MA Q X, ZHANG X T, LIU Y X. Influence of foundation pit excavation and building loading on nearby subway tunnel[J]. Geotechnical Engineering Technique, 2023, 37(3): 342-347. (in Chinese) doi: 10.3969/j.issn.1007-2993.2023.03.014 [6] 应宏伟, 杨永文. 杭州深厚软黏土中某深大基坑的性状研究[J]. 岩土工程学报, 2011, 33(12): 1838-1846. (YING H W, YANG Y W. Characteristics of a large and deep soft clay excavation in Hangzhou[J]. Chinese Journal of Geotechnical Engineering, 2011, 33(12): 1838-1846. (in Chinese)YING H W, YANG Y W. Characteristics of a large and deep soft clay excavation in Hangzhou[J]. Chinese Journal of Geotechnical Engineering, 2011, 33(12): 1838-1846. (in Chinese) [7] 宁波市住房和城乡建设局. 宁波市建筑基坑工程技术细则: 2019甬DX-06[S]. 北京: 中国建筑工业出版社, 2019. (Ningbo Municipal Bureau of Housing and Urban-Rural Development. Technical code for building foundation excavation engineering of Ningbo: 2019 YONG DX-06[S]. Beijing: China Architecture & Building Press, 2019. (in Chinese)Ningbo Municipal Bureau of Housing and Urban-Rural Development. Technical code for building foundation excavation engineering of Ningbo: 2019 YONG DX-06[S]. Beijing: China Architecture & Building Press, 2019. (in Chinese) [8] 周沈华, 杨有海, 王随新. 深基坑开挖对周边地表沉降影响因素分析[J]. 土工基础, 2008, 22(2): 38-42. (ZHOU S H, YANG Y H, WANG S X. Analyses of influence factors on ground settlement during excavation[J]. Soil Engineering and Foundation, 2008, 22(2): 38-42. (in Chinese) doi: 10.3969/j.issn.1004-3152.2008.02.011ZHOU S H, YANG Y H, WANG S X. Analyses of influence factors on ground settlement during excavation[J]. Soil Engineering and Foundation, 2008, 22(2): 38-42. (in Chinese) doi: 10.3969/j.issn.1004-3152.2008.02.011 [9] 武法伟, 李方明. 基坑开挖与降水引起的周边地表沉降变形耦合计算[C]//第九届全国工程地质大会论文集. 青岛: 中国地质学会工程地质专业委员会, 2012: 857-860. (WU F W, LI F M. The deformation coupling computation of ground subsidence caused by excavation of foundation pit and rainfall[C]//Proceedings of the 9th National Conference on Engineering Geology. Qingdao: Engineering Geology Professional Committee of the Geological Society of China, 2012: 857-860. (in Chinese)WU F W, LI F M. The deformation coupling computation of ground subsidence caused by excavation of foundation pit and rainfall[C]//Proceedings of the 9th National Conference on Engineering Geology. Qingdao: Engineering Geology Professional Committee of the Geological Society of China, 2012: 857-860. (in Chinese) [10] 中华人民共和国住房和城乡建设部. 建筑基坑支护技术规程: JGJ 120—2012[S]. 北京: 中国建筑工业出版社, 2012. (Ministry of Housing and Urban-Rural Development of the People’s Republic of China. Technical specification for retaining and protection of building foundation excavations: JGJ 120—2012[S]. Beijing: China Architecture & Building Press, 2012. (in Chinese)Ministry of Housing and Urban-Rural Development of the People’s Republic of China. Technical specification for retaining and protection of building foundation excavations: JGJ 120—2012[S]. Beijing: China Architecture & Building Press, 2012. (in Chinese) -
下载: