电渗-包裹碎石桩布置形式对软土加固效果影响的模型试验研究

Experimental study of arrangement type on the reinforcement effect of electric geotextile-encased stone columns in soft soil

为了提高包裹碎石桩复合地基承载力,提出利用电动土工织物作为碎石桩包裹套筒与电渗法联合处理的方法。同时为了探究电渗-包裹碎石桩处理软土工艺参数的影响,进行了两类电极布置形式(一字型、三角型)下的室内电渗模型试验,一字型布置设置3种电势梯度(0.2 V/cm,0.4 V/cm,0.6 V/cm),三角形布置分别设置阴阳极数目为1∶2、2∶1,获取电渗排水、通电电流、电渗结束后土体抗剪强度等试验结果。通过分析能耗系数变化规律和土体加固机理,研究电势梯度及包裹碎石桩布置形式对电渗-包裹碎石桩联合方法在软土地基加固中的影响。结果表明,能耗系数随电势梯度的增加而增大,电势梯度为0.2 V/cm时总体能耗系数较低且最终排水量大,工程中不宜选用过高电势梯度。联合方法对于桩周土处理效果较好,阳极区域附近土体抗剪强度提高主要由电渗作用引起,且沿深度方向衰减;阴极区域附近土体抗剪强度主要由排水体作用引起,距排水口越近加固效果越好。

To improve the bearing capacity of geosynthetic encased stone column(GESC) composite foundation,a combined method of electro-osmotic with electric geotextile as wrapping sleeve of GESC was proposed.Meanwhile,to explore the influence of the processing parameters in electro-osmosis combined with GESC on soft soil,indoor model tests at the laboratory scale with two types of electrode arrangement(line type and triangle type) were carried out.Three potential gradients(0.2 V/cm,0.4 V/cm,0.6 V/cm) were set for the line type arrangement,and the number of cathodes and anodes was set to 1∶2 and 2∶1 for the triangle type.The test results of drainage volume,electrified current,soil shear strength after the electro-osmotic process were obtained.The influence of the electric potential gradient and arrangement on the combined method was studied by analyzing the variation in the energy consumption coefficient and soil reinforcement mechanism.The results show that the energy consumption coefficient increases with increasing potential gradient.When the potential gradient is 0.2 V/cm,the overall energy consumption coefficient is low and the final discharge is large.So,it is not suitable to use a high potential gradient in engineering.The combined method has a good effect on the treatment of soil around the pile.The increase in the shear strength of the soil near the anode area is mainly caused by electro-osmosis and decays along the depth.The shear strength of the soil near the cathode area is mainly caused by the action of drainage water,and the closer to the drainage outlet,the better the reinforcement effect.