Experimental study on progressive collapse of tied-back retaining system of excavations induced by partial over-excavation or surcharge loading
-
摘要: 超挖或超载导致的基坑垮塌事故时有发生，然而局部超挖超载情况下基坑连续垮塌的全过程演化机理仍缺乏深入研究，限制了对此类基坑事故的针对性预防和控制。依托两起基坑垮塌案例，设计了桩锚支护基坑连续破坏模型试验，研究了局部超挖或超载对单道锚杆支护结构变形、土压力、锚杆轴力、支护桩及冠梁内力等的影响。结果表明，基坑局部超挖后，基坑外产生的土拱效应和冠梁荷载传递效应将导致邻近区域支护桩和锚杆内力大幅上升，此情况下超挖区内锚杆局部失效将进一步加剧这两个效应，引发邻近未失效锚杆连续破坏。支护桩嵌固深度较小时，锚杆失效后桩身弯矩始终减小，最终由于桩顶缺少约束而发生倾覆破坏；相反，当嵌固深度较大时，被动区土体对支护桩约束作用较强，最终支护桩的弯矩绝对值将显著提高，更可能发生弯曲破坏导致基坑垮塌。基坑正常开挖深度越大，超挖及锚杆失效产生的土拱效应越强，触发锚杆连续破坏所需的初始破坏锚杆越少，抗连续破坏能力越弱，应考虑局部加强锚杆，将局部破坏限制在一定范围。基坑顶部超载量过大将导致锚杆自超载范围中心向远端依次失效，进而引发基坑垮塌。锚杆设置高度不同，触发锚杆连续破坏的超载量不同，连续破坏路径和为应对潜在的超载风险需重点验算的构件也可能不同。锚杆设置在腰梁上时，超载情况下，锚杆的荷载传递系数大于支护桩，需优先考虑对锚杆进行局部加强设计；锚杆设置冠梁上时，触发锚杆连续破坏所需的超载量较腰梁工况更大，超载情况下，支护桩的荷载传递系数大于锚杆，应优先对支护桩考虑附加荷载作用进行设计。Abstract: Collapse accidents of tied-back excavations caused by over-excavation or overloading occasionally occur. However, the studies on the mechanism of progressive collapse under these conditions are still lacking, which limits the targeted prevention and control of such accidents. Based on two cases of excavation collapse, the model tests on the progressive failure of tied-back excavations are designed to investigate the influences of partial over-excavation or overloading on the deformation, earth pressure and internal forces of the anchors, piles and capping beam. The results show that after partial over-excavation, the soil arching effects generated outside the excavation and the load transfer effects of the capping beam cause a significant increase in the internal forces of the adjacent piles and anchors. Under this condition, the two effects are exacerbated by partial failure of anchors in the over-excavation area, leading to the progressive failure of the adjacent anchors. If their embedment depth is small, the bending moment of the piles decreases after the failure of the anchors, and finally the overturning failure occur due to the lack of constraint on the pile top. On the contrary, the maximum bending moments will increase and eventually leads to bending failure and collapse. The deeper the normal excavation depth, the stronger the soil arching effects caused by over-excavation and anchor failure, and the worse the capability to resist progressive failure of excavations. Therefore, the reinforcement of the anchors should be given priority to prevent progressive failure in the partial component strengthening method. The excessive surcharge load will cause progressive failure of the anchors from the center of the overloading area. Different anchor placement heights lead to different surcharge loads required to trigger the progressive failure of the anchors, the progressive failure path and the components that need to be specially checked against potential surcharge loading risks may also be different. When the anchors are set on the waler beam, the load transfer coefficient of the anchors is greater than that of the piles under surcharge loading, and the priority needs to be given to the design of local reinforcement of the anchors. When the anchors are set on the capping beam, a greater surcharge load is needed to trigger the progressive failure, and the load transfer coefficient of the piles is greater than that of the anchors, and the priority should be given to the design of the piles.
-
-
![]()
图 1 基坑底部局部超挖引起变形
Figure 1. Deflections of excavation induced by partial over-.excavation
![]()
图 8 超挖后主动区土压力增量（工况2）
Figure 8. Increments of active earth pressures after over-excavation (Test 2)
![]()
图 11 第5根锚杆失效瞬间主动区土压力增量（工况2）
Figure 11. Increments of earth pressures under failure of 5th anchor
![]()
图 12 局部锚杆失效过程P19桩后土压力变化
Figure 12. Earth pressures at P19 under partial failure of anchors
![]()
图 13 剩余锚杆连续破坏瞬间轴力变化图（工况2）
Figure 13. Axial forces of intact anchors at moment of progressive collapse(Test 2)
![]()
图 14 局部失效过程中剩余锚杆轴力增量及荷载传递系数变化
Figure 14. Increments of axial forces and load transfer coefficients of intact anchors under partial failure of anchors
![]()
图 15 局部锚杆失效过程冠梁剪力及变形图
Figure 15. Shear forces and deflections of capping beams under partial failure of anchors
![]()
图 16 局部锚杆失效过程桩身弯矩变化图
Figure 16. Bending moments of piles under partial failure of anchors
![]()
图 17 基坑垮塌瞬间桩身最大弯矩变化图
Figure 17. Maximum bending moments of piles at moment of progressive collapse
![]()
图 20 加载100 kg瞬间主动区土压力增量（工况4）
Figure 20. Increments of earth pressures with loading of 100 kg (Test 4)
![]()
图 21 加载各阶段埋深40 cm处主动区土压力增量
Figure 21. Increments of earth pressures at depth of 40 cm under surcharge loading
![]()
图 22 加载过程及连续破坏瞬间锚杆轴力时程变化
Figure 22. Axial forces of anchors during surcharge loading and progressive collapse
![]()
图 23 加载过程锚杆轴力增量及荷载传递系数变化
Figure 23. Increments of axial forces and load transfer coefficients of intact anchors under surcharge loading
![]()
图 24 加载各阶段冠（腰）梁弯矩变化
Figure 24. Bending moments of capping (waler) beam under surcharge loading
![]()
图 25 加载各阶段P19桩身位移弯矩变化图
Figure 25. Bending moments and deflections of P19 under surcharge loading
![]()
图 26 基坑垮塌前最后一级加载支护结构荷载传递系数对比
Figure 26. Load transfer coefficients at final stage of loading before excavation collapse
-
[1] ZHANG W G, HOU Z J, GOH A T C, et al. Estimation of strut forces for braced excavation in granular soils from numerical analysis and case histories[J]. Computers and Geotechnics, 2019, 106: 286-295. doi: 10.1016/j.compgeo.2018.11.006
[2] GOH A T C, ZHANG R H, WANG W, et al. Numerical study of the effects of groundwater drawdown on ground settlement for excavation in residual soils[J]. Acta Geotechnica, 2020, 15(5): 1259-1272. doi: 10.1007/s11440-019-00843-5
[3] 付文光, 杨志银, 刘俊岩, 等. 复合土钉墙的若干理论问题、兼论《复合土钉墙基坑支护技术规范》[J]. 岩石力学与工程学报, 2012, 31(11): 2291-2304. doi: 10.3969/j.issn.1000-6915.2012.11.018 FU Wenguang, YANG Zhiyin, LIU Junyan, et al. Some theoretical problems of composite soil nailing wall, and also on "technical specification for foundation pit support of composite soil nailing wall" [J]. Chinese Journal of Rock Mechanics and Engineering, 2012, 31(11): 2291-2304. (in Chinese) doi: 10.3969/j.issn.1000-6915.2012.11.018
[4] 孙海忠. 关于上海某基坑坍塌事故的分析研究[J]. 地下空间与工程学报, 2012, 8(增刊2): 1743-1746. SUN Haizhong. Research on one pit collapse in Shanghai[J]. Chinese Journal of Underground Space and Engineering, 2012, 8(S2): 1743-1746. (in Chinese)
[5] 钟铮. 软土地区某大面积基坑工程险情分析与处理[J]. 岩土工程学报, 2014, 36(增刊1): 231-236. ZHONG Zheng. Analysis and treatment for dangerous situations of a large foundation pit in soft soil areas[J]. Chinese Journal of Geotechnical Engineering, 2014, 36(S1): 231-236. (in Chinese)
[6] 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. ZHANG Kuangcheng, LI Jimin. 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)
[7] NISHA J J, MUTTHARAM M, VINOTH M, et al. Design, construction and uncertainties of a deep excavation adjacent to the high-rise building[J]. Indian Geotechnical Journal, 2019, 49(5): 580-594. doi: 10.1007/s40098-019-00368-4
[8] 苗领厚. 大规模超挖对深大基坑稳定性影响的研究[D]. 沈阳: 东北大学, 2015. MIAO Linghou. Stability Study on Massive Excavation to Deep and Large Foundation Pit[D]. Shenyang: Northeastern University, 2015. (in Chinese)
[9] YI F, SU J, ZHENG G, CHENG X S, et al. Overturning progressive collapse mechanism and control methods of excavations retained by cantilever piles[J]. Engineering Failure Analysis, 2022, 140: 106-591.
[10] 谢秀栋. 邻近建筑物超载时深基坑施工变形特性研究[J]. 岩土工程学报, 2008, 30(增刊1): 68-72. XIE Xiudong. Construction deformation characteristics of foundation pits under adjacent overloading buildings[J]. Chinese Journal of Geotechnical Engineering, 2008, 30(S1): 68-72. (in Chinese)
[11] 高亿文, 李明广, 陈锦剑. 超载影响下围护结构非对称基坑的受力及变形特性分析[J]. 上海交通大学学报, 2020, 54(6): 643-651. GAO Yiwen, LI Mingguang, CHEN Jinjian. Stress and deformation performance of deep excavation with asymmetrical retaining structures in adjacent surcharge[J]. Journal of Shanghai Jiaotong University, 2020, 54(6): 643-651. (in Chinese)
[12] YE J B, HE X L. Response of dual-row retaining pile walls under surcharge load[J]. Mechanics of Advanced Materials and Structures, 2022, 29(11): 1614-1625. doi: 10.1080/15376494.2020.1832286
[13] 王伟杰. 深基坑工程事故原因的分析及加固处理[J]. 居舍, 2018(19): 13, 65. WANG Weijie. Analysis and reinforcement of the accident in a deep excavation engineering[J]. Residential Houses, 2018(19): 13, 65. (in Chinese)
[14] 程雪松, 郑刚, 黄天明, 等. 悬臂排桩支护基坑沿长度方向连续破坏的机理试验研究[J]. 岩土工程学报, 2016, 38(9): 1640-1649. CHENG Xuesong, ZHENG Gang, HUANG Tianming, et al. Experimental study on mechanism of progressive collapse along length of excavation retained by cantilever contiguous piles[J]. Chinese Journal of Geotechnical Engineering, 2016, 38(9): 1640-1649. (in Chinese)
[15] CHENG X S, ZHENG G, DIAO Y, et al. Experimental study of the progressive collapse mechanism of excavations retained by cantilever piles[J]. Canadian Geotechnical Journal, 2017, 54(4): 574-587. doi: 10.1139/cgj-2016-0284
[16] 郑刚, 雷亚伟, 程雪松, 等. 局部破坏对钢支撑排桩基坑支护体系影响的试验研究[J]. 岩土工程学报, 2019, 41(8): 1390-1399. ZHENG Gang, LEI Yawei, CHENG Xuesong, et al. Experimental study on influences of local failure on steel-strutted pile retaining system of deep excavations[J]. Chinese Journal of Geotechnical Engineering, 2019, 41(8): 1390-1399. (in Chinese)
[17] ZHENG G, LEI Y W, CHENG X S, et al. Experimental study on the progressive collapse mechanism in the braced and tied-back retaining systems of deep excavations[J]. Canadian Geotechnical Journal, 2020, 58(4): 540-564.
[18] 建筑地基基础工程施工规范: GB 51004—2015[S]. 北京: 中国计划出版社, 2015. Gode for Construction of Building Foundation Engineering: GB 51004—2015[S]. Beijing: China Planning Press, 2015. (in Chinese)
[19] KARL T. Theoretical Soil Mechanics[M]. New York: J Wiley and Sons, Inc, 1943.
[20] 雷华阳, 刘旭, 加瑞, 等. 考虑土拱渐进发展的松动土压力研究[J]. 岩土工程学报, 2021, 43(8): 1434-1442. LEI Huayang, LIU Xu, JIA Rui, et al. Loosening earth pressure considering progressive development of soil arching[J]. Chinese Journal of Geotechnical Engineering, 2021, 43(8): 1434-1442. (in Chinese)
[21] 徐超, 张兴亚, 韩杰, 等. 加载条件对土拱效应影响的Trapdoor模型试验研究[J]. 岩土工程学报, 2019, 41(4): 726-732. XU Chao, ZHANG Xingya, HAN Jie, et al. Trapdoor model tests on impact of loading conditions on soil arching effect[J]. Chinese Journal of Geotechnical Engineering, 2019, 41(4): 726-732. (in Chinese)
[22] 郑刚, 雷亚伟, 程雪松, 等. 局部锚杆失效对桩锚基坑支护体系的影响及其机理研究[J]. 岩土工程学报, 2020, 42(3): 421-429. ZHENG Gang, LEI Yawei, CHENG Xuesong, et al. Influences and mechanisms of anchor failure on anchored pile retaining system of deep excavations[J]. Chinese Journal of Geotechnical Engineering, 2020, 42(3): 421-429. (in Chinese)
-
期刊类型引用(14)
1. 邹俊杰，尹志勇，彭蓬，吴沂洋，谭鹏强，高攀. 橡胶砂最小干密度测定及其经验公式. 建材技术与应用. 2024(03): 28-32 . 
百度学术
2. 孙小宸，宿利平，刘洋. 基于液化势指标的砂土抗液化评价方法及应用. 工程地质学报. 2023(02): 671-679 . 百度学术
3. 施勇，贾献林，吕国儿，李宝建. 钙质砂最大最小孔隙比的确定及其影响因素分析. 地基处理. 2023(04): 293-298 . 百度学术
4. 刘军，苗现国，许军龙，卓慧英，牛天娇. 砂土相对密度试验研究和探讨. 工程勘察. 2023(09): 26-34 . 百度学术
5. 瞿茹，朱长歧，刘海峰，王天民，马成昊，王星. 珊瑚砂界限干密度确定方法的比较研究. 岩土力学. 2023(S1): 461-475 . 百度学术
6. 李志鹏，糟凯龙，何建新，杨海华. 粉煤灰掺量对改良沙漠土毛细水上升规律的影响分析. 粉煤灰综合利用. 2022(01): 87-92 . 百度学术
7. 李识博，代俊芳，吴江伟，肖乐乐. 考虑粒组分类影响的最小孔隙比分布及模型验证. 岩土力学. 2022(S2): 193-204 . 百度学术
8. 戴仁辉，李明东，陈士军，易进翔，高玉峰. 不同粒度粗粒的极限孔隙比和破碎特征. 建筑材料学报. 2021(02): 427-431+439 . 百度学术
9. 王明年，江勇涛，张艺腾，于丽，曾正强. 渗透侵蚀下砂性土细颗粒流失率预测方法. 地下空间与工程学报. 2021(06): 1704-1712 . 百度学术
10. 刘勇，廖燕. 动荷载作用下砂土强度弱化的试验研究. 四川建筑科学研究. 2020(01): 65-70 . 百度学术
11. 赵文丽. 黏粒含量对砂土抗剪强度影响的试验研讨. 建材与装饰. 2020(18): 203+205 . 百度学术
12. 王明年，江勇涛，张艺腾，于丽，曾正强. 渗流作用下颗粒土起动临界坡降研究. 地下空间与工程学报. 2020(S1): 87-93 . 百度学术
13. 吴加武. 挤密砂桩在直立式护岸抗液化处理中的应用. 土工基础. 2019(01): 27-30+34 . 百度学术
14. 黎亮，杨晓松，李宏伟. 南疆绿洲区含残膜砂土击实特性试验研究. 公路. 2019(11): 199-203 . 百度学术
其他类型引用(14)
-
其他相关附件
下载:
计量
- 文章访问数: 362
- HTML全文浏览量: 45
- PDF下载量: 84
- 被引次数: 28
