上软下硬地层超深T形地连墙成槽施工难题的处理

埃及塞得东港集装箱码头二期工程的超深T形地下连续墙位于上软下硬且临海水位高的地层中，由于软弱土层深厚且槽孔深度超过60 m，因此成槽技术是施工的关键，需要解决槽壁易坍塌及确保槽孔垂直精度大于1/300这2个重大技 术难题。选择液压抓斗成槽机及旋挖钻机组合作为成槽施工的主要设备，施工中通过采取钻设引导孔、槽壁预加固、改善泥浆性能、保持槽内液面等一系列有效的技术措施，解决了成槽施工的重大技术难题。结果证明：超深T形墙的槽孔垂直精度高，没有塌孔现象，成槽时间较短，成本低，能够保证工程质量，取得了良好的社会效益和经济效益。

Treatment for trench construction puzzle of super-deep T-shape diaphragm wall in two- layered stratum

Super-deep T-shape diaphragm walls of Port Said East Container Terminal-Phase 2 Marine Works in Egypt are embedded in a two-layered stratum with soft upper and hard lower layers with high water head by sea. Because of more than 60 m depth of groove, the technology of trenching was crucial, and groove walls easy to collapse and its verticality insured more than 1/300 were two of momentous technical puzzles to be solved. Central equipments with hydraulic grab buckets and rotary drilling drivers were selected for the trench construction. In the process of trenching, some effective measures were adopted such as guide wall construction, groove walls advance reinforcement, mud of allocated proportion, liquid level controlling, etc., and momentous technical puzzles of trench construction were solved. Results show that the verticality of super-deep T-shape diaphragm walls is very well without its hole collapse. The trench can be finished with short time, low cost and good quality, and good social and economical benefits are gained.