考虑流固耦合作用的深基坑开挖支护体系变形分析

王泳海¹，李伟¹，卢善超¹，王日升^2*，张永壮²，吴鸿芮²，许茂林³，张韬⁴

1.山东泰山路桥工程集团有限公司，山东 泰安  271000；2.山东交通学院交通土建工程学院，山东 济南  250357；

3.山东东泰工程咨询有限公司，山东 淄博  255000；4.山东泰山交通规划设计咨询有限公司，山东 泰山  271000

摘要：为精准获得耦合场作用下基坑支护变形规律，以实际高水头工程为依托，采用有限元软件PLAXIS对多场耦合作用下的基坑开挖支护体系进行有限元模拟，工程开挖中对支护结构薄弱环节的水平位移、地表沉降及坑底隆起等关键变形指标实时监测，并将实测结果与模拟分析结果对比分析。结果表明：1）考虑高水头耦合作用的基坑开挖支护最大水平位移出现在距桩顶约7.5 m处，最大水平位移为41.771 mm，地表最大沉降位于距基坑约5.0 m处，最大沉降为32.682 mm，坑底最大隆起位于对称中心与桩体间的区域，最大隆起为19.600 mm；模拟变形规律与现场实测数据基本一致。2）实测数据介于考虑流固耦合作用的数值模拟计算结果与未考虑流固耦合作用的数值模拟结果间，且整体上更接近前者。3）支护桩水平位移、桩周土体沉降和坑底隆起的最大模拟结果可作为现场监测预警阈值，高水头区域基坑开挖深度增大后变形增大，应及时进行支护。

关键词：基坑支护；渗流；耦合场；数值模拟

Analysis of deformation in deep excavation support systems considering fluid-structure interaction

WANG Yonghai¹, LI Wei¹, LU Shanchao¹, WANG Risheng^2*, ZHANG Yongzhuang², WU Hongrui², XU Maolin³, ZHANG Tao⁴

1.Shandong Taishan Road & Bridge Engineering Group Co., Ltd., Taishan 271000, China;

2.School of Civil Transportation Engineering, Shandong Jiaotong University, Jinan 250357, China;

3.Shandong Dongtai Engineer Consulting Co., Ltd., Zibo 255000, China;

4.Shandong Taishan Transportation Planning and Design Cosulting Co., Ltd., Taian 271000, China

Abstract: To precisely obtain the deformation patterns of retaining and protecting for foundation excavation under the coupling field effects, based on an actual high water head project, finite element software Plaxis is used to conduct finite element simulations of the foundation pit excavation support system under multi-field coupling effects. During the engineering excavation, key deformation indicators such as horizontal displacement of weak links in the support structure, surface settlement, and bottom uplift are monitored in real-time, and the measured results are compared and analyzed with the simulation analysis results. The results show that: 1) The maximum horizontal displacement during the foundation pit excavation considering high water head coupling effects occurs about 7.5 m from the top of the pile, with a maximum horizontal displacement of 41.771 mm; The maximum surface settlement is located approximately 5.0 m from the foundation pit, with a maximum settlement of 32.682 mm; The maximum uplift at the bottom of the pit is found in the area between the symmetric center and the pile body, with a maximum uplift of 19.600 mm; The simulated deformation patterns are generally consistent with the field measured data. 2) The measured data lie between the numerical simulation results that consider fluid-solid coupling effects and those that do not, and overall, they are closer to the former. 3) The maximum simulated results of horizontal displacement of support piles, settlement of surrounding soil, and uplift at the bottom of the pit can serve as warning thresholds for on-site monitoring. As the excavation depth increases in high water head areas, the deformation increases, and timely support should be implemented.

Keywords: retaining and protecting for foundation excavation; seepage flow; coupling field; numerical simulation