砂土地层中泥浆护壁地连墙成槽稳定性分析

Effect of slurry infiltration on trench stability of diaphragm wall in sand

饱和砂土地层中的地下连续墙开挖,常伴有槽壁失稳、坍塌等事故的发生。但目前针对砂土地层的泥浆渗透规律和泥浆渗透下槽壁稳定性的研究较少。故基于泥浆渗透和扩散机制,建立考虑泥浆运移、流速变化、土层孔隙变化耦合的土层泥浆渗透分析模型,通过与既往模型试验对比标定模型参数。基于平面应变模型模拟地下连续墙槽段泥浆渗透过程,探究泥浆比重和砂土孔隙对泥皮形成质量和泥浆渗透范围的影响。采用强度折减法对不同泥浆渗透阶段下砂土地层槽段稳定性进行分析,对不同泥浆密度、不同地层孔隙率对槽段稳定性的影响研究表明,松散砂土地层中需适当提高泥浆浓度以确保槽段稳定性。最后,结合实际工程对比模拟验证其合理性。

Instability and even collapse of slurry trench may occur during the excavation of diaphragm wall in saturated sand.At present,there are few analyses on the slurry infiltration and the stability of slurry trench in sand.Based on the mechanism of slurry penetration and diffusion,a model for slurry infiltration in sand is established to consider the coupling relationship among the degree of slurry infiltration,velocity variation and soil pore change.The model parameters are calibrated by comparing with the existing tests.Plane-strain models are further established to simulate the slurry infiltration after the trench excavation.The influences of slurry specific gravity and sand pore on the quality of mud cake and the infiltration range of slurry are then discussed.The influences of slurry density and soil porosity on the trench stability under slurry infiltration in sand are further analyzed by strength reduction method.It shows that a proper increase in slurry concentration is beneficial for the trench stability in loose sand.Finally,the method is applied to a practical engineering for further verification.