交通荷载下粉质黏土路基翻浆冒泥机理试验

Experiments to investigate mechanism of mud pumping of road base on silty clay soil under cyclic loading

为研究粉质黏土路基翻浆冒泥发生规律,自主研制了一套路基翻浆冒泥模型试验装置。模型中路基层分别采用级配碎石与粉质黏土进行填筑,试验研究了交通循环荷载下路基中孔压累积、翻浆冒泥与沉降发展全过程,分析了粉质黏土地基土体成分、孔隙比等对路基翻浆冒泥的影响规律。研究表明:交通循环荷载下地基内部孔隙水压逐渐累积,当地基中有效应力为零时出现瞬态液化并发生翻浆冒泥现象。针对易发生翻浆冒泥的粉质黏土地基,试验发现黏粒含量与孔隙比是影响路基翻浆冒泥的重要参数;黏粒含量增加将使地基中孔压累积,进而发生翻浆冒泥现象;而同样黏粒含量下,地基孔隙比减小将使路基翻浆冒泥现象受到抑制。基于试验结果,在塑性指数和孔隙比坐标系下提出了地基翻浆冒泥的判别参考准则,当塑性指数与孔隙比位于该判定准则上方时,可初步判定路基易发生翻浆冒泥。本文研究可为交通荷载下道路翻浆冒泥评价与控制提供参考。

To investigate the mechanism of mud pumping of road base on silty clay foundation,a self-made apparatus has been designed and manufactured.The subbase and subgrade were simulated by graded ballast and silty clay,respectively.A series of mud pumping tests had been conducted to investigate the development law and occurrence condition of mud pumping with different fines content and void ratio.The experiment results show that the pore water pressure accumulates under the cyclic loading.When the effective stress turns negative,the soil liquefaction occurs,which leads to the mud pumping of the road base.Furthermore,the fine content and void ratio are important parameters to mud pumping in silt clay foundation,the development of mud pumping can be aggravated by the increase of the fine content and the void ratio.A criterion including plastic index(IP)and void ratio(e)of the foundation has been proposed to determine the occurrence of mud pumping.When above the criterion,the foundation is susceptible to mud pumping.The study can provide a reference for prediction and control of the mud pumping of road on soft soil.