大型基坑工程区域一般地质情况复杂,基坑施工安全面临诸多不确定因素,有一定的施工风险。利用有限元对基坑开挖过程进行模拟分析,依据预测结果确定施工预案,及时采取相应措施,确保基坑开挖和基坑结构的安全。以南京市长江第四大桥南锚碇基础工程为例,采用通用有限元软件Midas-GTS对工程进行了三维建模,分析了施工中地连墙和中隔墙的变形和应力。结果表明：支护体系的内力在可承受的范围内；支护体系在施工阶段的最大变形约4.1 mm,属于很低的水平；锚碇南北两侧土层的差异对体系的变形、内力影响不大。为大型基坑开挖施工的研究与应用提供了技术手段和参考资料。%With the complex geological situation in the project area of large foundation pit, the constructional safety of founda-tion pit was challenged by many uncertain factors and some constructional risks. The excavation process was simulated and ana-lyzed on the basis of finite element method and the constructional plan and safety measures can be determined by the prediction results. With the case of the south anchorage foundation project of No. 4 Yangtze River Bridge in Nanjing, the three-dimension-al construction modeling was conducted with the use of general finite element software Midas-GTS. Meanwhile, the deformation and stress of diaphragm retaining wall and partition wall during the construction process were also analyzed. The results showed that the internal forces of the support system were at affordable range;the maximum deformation during construction phase is a-bout 4. 1 mm which belongs to a very low level;the soil layer difference of the north and south sides of the anchorage foundation has little effect on the deformation and internal force.
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