地下连续墙成槽施工槽壁稳定机制分析

针对地下连续墙成槽施工过程中的槽壁稳定性及其失稳现象，分别从地下连续墙槽壁稳定影响因素、槽壁整体及局部失稳机制、不同施工阶段槽壁土体的应力路径3个方面进行分析。研究结果表明：浅层失稳是泥浆护壁成槽施工过程中槽壁整体失稳的主要形式，局部失稳多由槽壁土体砂性较重及槽段内泥浆液面波动过大引起；适当增加泥浆比重、提高泥浆液面标高、槽壁预加固、控制成槽机械地面超载及降低开挖对土体的扰动可有效保证槽壁的稳定；开挖后槽壁稳定性会随土体负孔隙水压力的消散而下降，成槽后应及时吊放钢筋笼并及早浇筑混凝土。

ANALYSIS OF TRENCH FACE STABILITY OF DIAPHRAGM WALL PANEL DURING SLURRY TRENCHING

Some key issues including inner and outer influencing factors of trench face stability，overall and local instability mechanism of trench face，and stress path of soil element near trench face are discussed in detail to investigate the trench face stability and instability performance during slurry trenching for diaphragm wall panels. The research results show that shallow ground collapse is the major trench face overall instability pattern during slurry trenching，and trench face local collapse is commonly caused by heavily sandy of soil and excessive fluctuation of slurry flux level. Some precautionary construction measures，including increasing unit weight of slurry appropriately，raising slurry fluid level，pre-reclamation of trench face soil，control of trenching machine overloading and manipulation of soil disturbance during slurry trenching，are the most effective countermeasures to ensure the trench face stability. The trench face stability decreases with the dissipation of negative pore pressure after slurry trenching. Therefore，reinforcement cages should be placed into trench in time and concrete should be casted as soon as possible to guarantee the trench face stability.