带撑双排地下连续墙支护结构在清远枢纽航道扩容工程中的应用研究

正在紧张施工的广东省清远枢纽航道扩容之二线船闸的深基坑工程紧邻一线船闸,覆盖层深厚,地层性质较差,地质条件复杂,坑外设计洪水位较高。考虑到基坑开挖过程中已建船闸和基坑的相互作用,为满足支护结构自身强度及变形要求,避免由于基坑开挖过程中土体卸荷造成邻近已建船闸产生过大变形从而对船闸安全稳定和正常运行带来安全隐患,二线船闸的闸室部分的基坑支护结构采用带撑双排地下连续墙方案。以带撑双排地下连续墙为研究重点,利用迈达斯GTS有限元软件,基于硬化土(HS)土体本构模型,模拟清远二线船闸深基坑施工过程。有限元结果表明,双排地下连续墙支护结构和邻近船闸闸室的水平位移特征与工程实测结果基本吻合,带撑双排地下连续墙支护方案对于二线船闸深基坑工程是可行的。

Application of braced retaining structures with double-row diaphragm walls in channel expansion project of Qingyuan junction

The deep foundation pit of the second-line ship lock in the channel expansion project of Qingyuan junction in Guangdong Province is under construction. It is close to the first-line ship lock, with deep overburden, poor formation property, complicated geological condition and high flood level. Considering the interaction between the ship lock and the foundation pit in the excavation process of the foundation pit, the braced retaining structures with double-row diaphragm walls are adopted as those of the foundation pit of the lock chamber part of the second-line ship lock. It is designed to meet the requirements of the strength and deformation of the retaining structures and to avoid the excessive deformation of the adjacent built ship lock, which will bring security risks to the stability and normal operation of the ship lock due to unloading during the excavation of the foundation pit. For the braced retaining structures with double-row diaphragm walls, based on the hardening soil constitutive model, the construction process of the deep foundation pit of the second-line ship lock of Qingyuan junction is simulated by means of the Midas GTS finite element software. The results show that the characteristics of horizontal displacement of the double-row diaphragm walls and the lock chamber of the adjacent ship lock in the excavation of the foundation pit are basically in accordance with the measured results. The scheme of the braced retaining structures with double-row diaphragm walls is feasible in the deep excavation project of the second-line ship lock.