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.