基于悬浮颗粒物沉淀理论DCM桩浅表砂层成桩问题分析及应对策略

Analysis and Countermeasures of the Problem of Pile Forming in Shallow Surface Sand Layer of DCM Pile Based on Suspended Particulate Matter Precipitation Theory

水下深层水泥土搅拌桩(DCM桩)是一种应用于水下复合地基处理可靠手段,是实现围海造陆、人工岛、大型海底隧道等超级工程水下地基加固处理关键技术之一,然而工程中会遇到在浅表砂层地质条件下局部成桩困难的问题。通过室内模拟试验,基于斯托克斯公式计算不同颗粒沉淀速度的理论,得出了在浅表砂层地质条件下难以成桩的原因是该区域容易发生自由分层沉淀,致使DCM桩局部不能成桩。针对该地质条件的特性,有针对性地提出了相应的应对措施。

Underwater deep cement soil mixing pile( DCM pile) is a reliable mean for underwater composite foundation treatment. It is one of the key technologies for the super engineering subsoil consolidation treatment,such as land reclamation,artificial island,large seabed tunnel and so on. However,it can appear the problem of local pile forming is difficult in the shallow surface sand ground. Through the indoor simulation test and the Stokes formula theory of calculating the precipitation velocity of different particles,it is concluded that the reason of being difficult to make a pile under the geological condition of the shallow surface sand layer is that the free stratified precipitation is easy to occur in this area,resulting the local failure of the DCM pile. According to the characteristics of the geological conditions,corresponding countermeasures are put forward accordingly.