Variation of axial force of steel struts in deep excavations
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摘要: 钢支撑轴力实测数据离散、变化规律性不清是钢支撑设计的重要问题，严重影响着深基坑工程安全和工程经济合理性。以南京地铁某车站软土基坑工程为例，通过建立三维有限元模型，研究了钢支撑轴力变化规律。结合基坑开挖过程中的监测数据，提出了钢支撑轴力与围护墙体位移双元组合的方法，验证了模型合理性，同时揭示了深基坑开挖过程中围护墙位移和支撑轴力变化的相关性规律。然后研究了单道、双道预加轴力对钢支撑轴力、墙体位移和弯矩的影响，提出了采用预加轴力技术控制变形的基本要求，研究了支撑架设条件的影响，阐明了支撑轴力实测值离散的原因和超挖对基坑安全的重要影响，进而明确了悬挂架设钢支撑的研究意义。研究成果对厚层软土深基坑的变形控制技术发展提供了新方向。Abstract: The discrete data and unclear variation trend of axial force of steel structs are the important design problems, which seriously affect the safety and economic rationality of deep excavations. A three-dimensional finite element model for a deep soft excavation in Nanjing Metro station is established to study the variation of axial force of steel struts. Based on the monitoring data in the process of excavation, the dual-combination method for the axial forces of steel struts and wall deflection is put forward to validate the rationality of the model and parameters. The correlation between the wall deflection and the axial force of steel struts during is excavation revealed. Then, the influences of single- and double-axial preloading on the axial forces of steel structs, wall deflection and moment are studied to propose the basic requirements of using the preloading axial force technology to control deformation. The influences of struct erection conditions are studied to expound the reason of the discrete measured values of axial force of steel struts and the important influences of over-excavation on the safety of engineering, and to reveal the research significance of hanging steel struct erection. The research results may provide a new direction for the development of deformation control technology of deep excavations in thick soft soils.
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图 4 围护墙体位移模拟值和实测值对比图
Figure 4. Comparison between simulated and measured values of wall deflection
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图 5 基坑开挖过程中的钢支撑轴力模拟值与实测值对比图
Figure 5. Comparison between simulated and measured values of axial forces of steel struts during excavation
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图 6 基坑开挖过程中的围护墙体位移最大值及相对值
Figure 6. Maximum and relative values of wall deflection during excavation
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图 7 基坑开挖过程中的钢支撑轴力及其总和
Figure 7. Axial forces and sum of steel structs during excavation
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图 8 围护墙体位移最大值与钢支撑轴力总和的关系
Figure 8. Relationship between maximum wall deflection and sum of axial force of steel struts
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图 9 第二道钢支撑预加轴力对轴力及墙体位移的影响
Figure 9. Influences of preloading of secondary steel structs on axial forces and wall deflection
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图 10 改变第二、第三道钢支撑预加轴力
Figure 10. Influences of preloading axial force on struts No. 2 and No. 3
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图 11 第二、第三道支撑不同预加轴力下围护墙体位移
Figure 11. Comparison of wall deflection under different preloading axial forces on struts No. 2 and No. 3
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图 12 第二、第三道支撑不同预加轴力下围护墙体弯矩
Figure 12. Comparison of wall moment under different preloading axial forces on struts No. 2 and No. 3
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图 14 不同架设条件下钢支撑轴力值变化
Figure 14. Variation of axial force of steel structs under different erection conditions
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图 15 不同支撑架设条件下围护墙体位移
Figure 15. Wall deflections under different strut erection conditions
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图 16 不同支撑架设条件下围护墙弯矩图
Figure 16. Wall moments under different strut erection conditions
表 1 土层模型计算参数
Table 1 Parameters for soil model
土层 弹性模量/MPa 泊松比 饱和重度/(kN·m-3) 初始孔隙比 黏聚力/kPa 内摩擦角/(°) 杂填土 4.1 4.1 16.4 0.34 19.0 0.9 10 9.0 素填土 4.1 4.1 16.4 0.34 18.8 0.9 15 5.4 淤泥质粉质黏土 3.3 3.3 13.2 0.41 18.2 1.1 12 5.7 粉质黏土夹粉砂 3.7 3.7 16 0.34 18.7 1.0 14 8.4 
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表 2 支护结构材料参数
Table 2 Parameters for support structures
结构名称 单元类型 弹性模量/GPa 泊松比 重度/(kN·m-3) 尺寸/mm 地下连续墙 板 31.5 0.2 26.0 厚度t=800 钻孔灌注桩 梁 31.5 0.2 26.0 桩径1000 格构柱 梁 200.0 0.3 78.5 方箱480, t=20 钢筋混凝土支撑 梁 31.5 0.2 26.0 矩形100×800 钢支撑 梁 200.0 0.3 78.5 ¬609, t=16
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表 3 基坑开挖模拟步骤
Table 3 Simulation steps of excavation
序号 施工阶段 单元处理 1 初始应力分析 激活所有土体、自重、边界约束；位移清零 2 围护墙施工 激活围护墙、围护墙旋转约束 3—4 开挖第1—第2层土 逐步钝化第1—第2层土 5 架设第一道支撑 激活第一道钢筋混凝土支撑 6—10 开挖第3—第7层土 逐步钝化第3—第7层土 11 架设第二道支撑 激活第二道钢支撑 12—15 开挖第8—第11层土 逐步钝化第8—第11层土 16 架设支撑3 激活第三道钢支撑 17—19 开挖第12—第14层土 逐步钝化第12—第14层土 20 架设支撑4 激活第四道钢支撑 21—22 开挖第15—第16层土 逐步钝化第15—第16层土
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表 4 模拟值与实测值相对误差汇总表
Table 4 Summary of relative errors between simulated and measured values
/% 测项 模拟值与实测值相对误差 开挖7 m 开挖11 m 开挖14 m 开挖16 m 围护墙体位移 1 -6 -1 4 第二道轴力 12 17 9 5 第三道轴力 — 14 22 20 第四道轴力 — — 5 8
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表 6 第二、第三道钢支撑预加轴力影响
Table 6 Influences of preloading axial force on struts No.2 and No.3
计算模式 预加轴力/kN 初始轴力/kN 最大轴力/kN 最终轴力/kN 设计轴力/kN 方案Ⅰ 第二道 1600 1787 2610 2285 2313 第三道 1600 1701 2800 2800 1543 第四道 1050 999 1215 1215 1915 方案Ⅱ 第二道 3000 2014 2806 1988 2313 第三道 3000 2499 3340 3340 1543 第四道 1050 968 1182 1182 1951
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表 7 各架设条件下钢支撑最大轴力值
Table 7 Maximum axial forces of steel struts under various erection conditions
(kN) 项目 第二道 第三道 第四道 悬挂架设 1544 1893 2266 常规架设 2228 3182 997 超挖1 m 4026 1159 3904 设计方案 2313 1543 1951 实际方案 2015 2627 926
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表 8 不同支撑架设条件下围护墙位移、弯矩最大值
Table 8 Wall deflections and maximum moments under different strut erection conditions
项目 最大位移/mm 最大正弯矩/(kN·m) 最大负弯矩/(kN·m) 悬挂架设 68 1729 -603 常规架设 110 2412 -1045 超挖1 m 204 3354 -1996
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[1] 蒋洪胜, 刘国彬. 软土深基坑支撑轴力的时空效应变化规律研究[J]. 岩土工程学报, 1998, 20(6): 105–107. http://manu31.magtech.com.cn/Jwk_ytgcxb/CN/abstract/abstract10234.shtml JIANG Hong-sheng, LIU Guo-bin. Time-space effect on strut force in deep excavation of soft soil[J]. Chinese Journal of Geotechnical Engineering, 1998, 20(6): 105–107. (in Chinese) http://manu31.magtech.com.cn/Jwk_ytgcxb/CN/abstract/abstract10234.shtml
[2] GOLDBERG D T, JAWORSKI W E, GORDON M D. Lateral Support Systems and Underpinning[R]. Washington: Federal Highway Administration, 1976.
[3] 曹雪山, 张荣宽, 顾琴. 一种深基坑变形报警方法: CN105064371B[P]. 2017-07-18. CAO Xue-shan, ZHANG Rong-kuan, GU Qing. Deformation alarming method for deep foundation pit: CN105064371B[P]. 2017-07-18. (in Chinese)
[4] 陈保国, 闫腾飞, 王程鹏, 等. 深基坑地连墙支护体系协调变形规律试验研究[J]. 岩土力学, 2020, 41(10): 3289–3299. https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX202010014.htm CHEN Bao-guo, YAN Teng-fei, WANG Cheng-peng, et al. Experimental study on compatible deformation of diaphragm wall support system for deep foundation pit[J]. Rock and Soil Mechanics, 2020, 41(10): 3289–3299. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX202010014.htm
[5] 金亚兵, 沈翔, 劳丽燕. 温度变化对深基坑内支撑轴力和变形的影响研究[J]. 岩土工程学报, 2021, 43(8): 1417–1425. http://manu31.magtech.com.cn/Jwk_ytgcxb/CN/abstract/abstract18689.shtml JIN Ya-bing, SHEN Xiang, LAO Li-yan. Influences of temperature change on axial force and deformation of inner support in deep foundation pits[J]. Chinese Journal of Geotechnical Engineering, 2021, 43(8): 1417–1425. (in Chinese) http://manu31.magtech.com.cn/Jwk_ytgcxb/CN/abstract/abstract18689.shtml
[6] 刘国彬, 王卫东. 基坑工程手册[M]. 第2版. 北京: 中国建筑工业出版社, 2009: 1108–1150. LIU Guo-bin, WANG Wei-dong. Excavation Engineering Manual[M]. 2nd ed. Beijing: China Architecture & Building Press, 2009: 1108–1150. in Chinese)
[7] 建筑基坑支护技术规程: JGJ 120—2012[S]. 2012. Technical Specification for Retaining and Protection of Building Foundation Excavations: JGJ 120—2012[S]. 2012. (in Chinese)
[8] 曹雪山, 额力素, 曹怀玉. 深基坑钢支撑预加力对围护墙变形影响[J]. 河北工程大学学报(自然科学版), 2020, 37(3): 33–39. https://www.cnki.com.cn/Article/CJFDTOTAL-HJXU202003005.htm CAO Xue-shan, E Li-su, CAO Huai-yu. Influence of inner steel strut prestress on the retaining wall deformation of deep excavation[J]. Journal of Hebei University of Engineering (Natural Science Edition), 2020, 37(3): 33–39. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-HJXU202003005.htm
[9] 建筑基坑工程监测技术规范: GB 50497—2009[S]. 2009. Technical Code for Monitoring of Building Excavation Engineering: GB 50497—2009[S]. 2009. (in Chinese)
[10] 江苏省城市轨道交通工程监测规程: DGJ32—J195— 2015[S]. 2015. Technical Specification for Monitoring Measurement of Urban Rail Transit Engineering in Jiangsu Province: DGJ32—J195—2015[S]. 2015. (in Chinese)
[11] 李书银, 李世良. 地铁深基坑钢支撑预加轴力消散原因分析[J]. 铁道勘察, 2018, 44(5): 39–42. https://www.cnki.com.cn/Article/CJFDTOTAL-TLHC201805010.htm LI Shu-yin, LI Shi-liang. Analysis on dissipation of preloaded axial force of steel support in subway deep foundation pit[J]. Railway Investigation and Surveying, 2018, 44(5): 39–42. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-TLHC201805010.htm
[12] 洪德海. 钢支撑预加力对围护结构内力的影响分析[J]. 铁道勘察, 2010, 36(2): 62–64. https://www.cnki.com.cn/Article/CJFDTOTAL-TLHC201002021.htm HONG De-hai. Analysis on influence of steel support prestress on endogenous force of support structure[J]. Railway Investigation and Surveying, 2010, 36(2): 62–64. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-TLHC201002021.htm
[13] CLOUGH G W, TSUI Y. Performance of tied-back walls in clay[J]. Journal of the Geotechnical Engineering Division, 1974, 100(12): 1259–1273.
[14] 建筑基坑工程监测技术标准: GB 50497—2019[S]. 2019. Technicai Standard for Monitoring of Building Excavation Engineering: GB 50497—2019[S]. 2019. (in Chinese)
[15] 张洁玲. 某地铁车站深基坑开挖变形及稳定性研究[D]. 石家庄: 石家庄铁道大学, 2018. ZHANG Jie-ling. Study on the Excavation Deformation and Stability of Deep Foundation Pit in Subway Station[D]. Shijiazhuang: Shijiazhuang Tiedao University, 2018. (in Chinese)
[16] 雷霆, 丁保华, 张瑞鑫, 等. 钢支撑有限元模型刚度取值研究[J]. 市政技术, 2020, 38(1): 220–223. https://www.cnki.com.cn/Article/CJFDTOTAL-SZJI202001075.htm LEI Ting, DING Bao-hua, ZHANG Rui-xin, et al. On stiffness values of finite element model in steel support structure[J]. Municipal Engineering Technology, 2020, 38(1): 220–223. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-SZJI202001075.htm
[17] 杨学涛, 曹雪山. 深基坑围护结构水平位移变形分析[J]. 施工技术, 2014, 43(13): 51–54. https://www.cnki.com.cn/Article/CJFDTOTAL-SGJS201413016.htm YANG Xue-tao, CAO Xue-shan. Horizontal displacement analysis on deep foundation excavation retaining structure[J]. Construction Technology, 2014, 43(13): 51–54. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-SGJS201413016.htm
[18] 杨学涛. 南京河西某深基坑变形特征及对周围建筑物的影响分析[D]. 南京: 河海大学, 2015. YANG Xue-tao. Study on Deformation of Deep Foundation Pit in Soft Area and Influence to Building Adjacented, Hexi, Nanjing[D]. Nanjing: Hohai University, 2015. (in Chinese)
[19] 吴昌将, 孙召花, 赖允瑾, 等. 软土地区地下连续墙深大基坑的变形性状研究[J]. 岩土力学, 2018, 39(增刊2): 245–253. https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX2018S2035.htm WU Chang-jiang, SUN Zhao-hua, LAI Yun-jin, et al. Study of deformation characteristics of diaphragm wall induced by deep large excavation in soft soil region[J]. Rock and Soil Mechanics, 2018, 39(S2): 245–253. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX2018S2035.htm
[20] 张旷成, 李继民. 杭州地铁湘湖站"08.11. 15"基坑坍塌事故分析[J]. 岩土工程学报, 2010, 32(增刊1): 338–342. https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC2010S1068.htm ZHANG Kuang-cheng, LI Ji-min. Accident analysis for "08.11. 15" foundation pit collapse of Xianghu Station of Hangzhou metro[J]. Chinese Journal of Geotechnical Engineering, 2010, 32(S1): 338–342. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC2010S1068.htm
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