基于PFC3D的地下连续墙槽壁稳定性模拟分析

Trench wall stability simulation for the diaphragm wall based on PFC3D

摘要:

针对富水砂卵石层地下连续墙成槽过程中槽壁易发生失稳的问题，通过分析相关的研究资料，在明确失稳形式及机理的基础上，设计了改变流速和粒径比的两种模拟试验方案，采用PFC^3D颗粒流软件分析了渗流对土颗粒间性质变化的影响。数值模拟结果表明：流速对于颗粒的位移有很大的影响。流速越快，颗粒位移越大，孔隙率越高，墙体所受应力也越大；粒径比对于颗粒的位移同样有很大影响，其表现的作用与流速相似；在有侧限的情况下，颗粒的x向位移在达到极限后会产生z向的分量，使得颗粒向上位移。在实际工程中就意味着在颗粒位移达到一定程度，必然会突破泥膜，导致土体内细颗粒的流失，土体孔隙率增大，最终使得槽壁发生垮塌。

关键词:PFC^3D;富水砂卵石层;槽壁稳定性;数值模拟;地下连续墙

Abstract:

In view of the problem that the trench wall for the diaphragm wall is prone to failure in the process of trench-digging in water rich sand pebble formation， two simulation test schemes are designed with either change of the flow velocity or the particle size ratio by analyzing the relevant research data and on the basis of defining the failure form and mechanism. The numerical simulation results show that the flow velocity has a great influence on the displacement of particles. The faster the flow velocity， the greater the particle displacement， the higher the porosity， and the greater the stress on the wall. The particle size ratio also has a great influence on the displacement of particles， and its effect is similar to that of flow velocity. When there is a lateral limit， the x-direction displacement of the particles will produce a z-direction component after reaching the limit， making the particles move upward. In practical works， it means that when the particle displacement reaches a certain degree， it will inevitably break through the mud film， resulting in the loss of fine particles in the soil， the increase of soil porosity， and finally the collapse of the trench wall.

Key words:PFC^3D;water rich sand pebble layer;trench wall failure;numerical simulation;diaphragm wall