超大深基坑支护结构设计及稳定性分析

Design and Stability Analysis of a Supporting Structure for a Very-Large Deep Excavation

以江苏省某过江通道基坑工程为依托,提出地连墙+内支撑+N-JET注浆基底加固的基坑支护方案,并采用数值模拟方法建立三维数值模型,研究了基坑开挖对支护结构及周边既有建构筑物的影响。研究结果表明:基坑开挖后,支护结构位移和受力较小,北侧地连墙和东西侧地连墙深层水平位移最大值分别为13.4 mm和7.2 mm,支撑结构所受最大轴力为14 868 kN,地连墙墙身应力最大值为1.31 MPa,周边地表沉降值较小,验证了基坑支护方案的有效性,能够保证该深大基坑工程顺利施工。研究结果可为类似基坑的设计和施工提供参考和借鉴。

This paper presents a case history of a deep excavation support design project for a a river crossing tunnel in Jiangsu Province.The deep excavation supporting method of the diaphragm wall+internal support+bottom reinforcement by using N-JET grouting is proposed.A three-dimensional numerical model is established by using the numerical simulation method to study the impact of deep excavation on the supporting structure and surrounding structures.The results show that,after the excavation,the displacement and stress of the supporting structure are small,the maximum horizontal displacement of the deep layer of the north diaphragm wall and the east and west diaphragm walls are 13.4 mm and 7.2 mm respectively,The maximum axial force on the supporting structure is about 14868 kN,the maximum stress on the diaphragm wall is about 1.31 MPa,and the surrounding surface settlement is small,which verifies the effectiveness of the excavation support method and can ensure the smooth construction of the deep and large deep excavation project.The results can provide a good reference for the design and construction of similar projects.