咸水中胶体迁移-沉积对砂介质渗透性损失的数学模型

Mathematical Model of Colloid Transport-Deposition on Permeability Loss of Sand Medium in Salt Water

采用室内土柱试验,研究咸水中胶体迁移引起砂介质渗透性变化的特征,通过胶体迁移-沉积作用的分析对砂介质渗透性损失的机理进行了探讨.结果表明:砂介质渗透性随孔隙体积数变化的动态特征符合Boltzmann函数;砂介质渗透性总的损失率为37.4%;渗透系数的损失量随孔隙体积数的增加而增加.胶体在砂介质中的穿透曲线呈"S"型,其中的2个拐点将曲线分成开始穿透、快速穿透和平稳穿透3个阶段,但并没有完全穿透,其迁移过程中发生了沉积.胶体沉积作用是砂介质渗透性降低的主要原因.

On the basis of field investigation,self-designed column experiments were conducted to elucidate the effect of colloid transport on the permeability of sand medium in salt water.Moreover,the mechanism of sand medium permeability loss was discussed by studying the transport and deposition of colloids in the column.The results show that the dynamic characteristic of sand medium permeability changes with pore volumes is consistent with the Boltzmann function.The total loss ratio of sand medium permeability is 37.4% ,and the loss of permeability coefficient increased with the increasing of pore volumes.The breakthrough curves of the colloids presents as＂S＂type,and could be divided into three phases：start to breakthrough,fast breakthrough,and smooth breakthrough,but none of them broke through completely.The deposition of colloids was the main reason for the permeability loss of the sand medium.