饱和砂层中颗粒迁移特性试验研究:温度效应

Experimental research on the transport characteristics of particles in saturated sand:temperature effect

为探索温度对饱和砂层中悬浮颗粒迁移-沉积过程的影响,采用自主研发的砂层迁移-沉积模拟试验系统,分别进行不同温度下颗粒迁移-沉积特性试验和温度变化条件下颗粒迁移-沉积特性试验。试验针对4种粒径组合进行4种温度(5℃,15℃,25℃,35℃)条件下的相关试验。结果表明,在渗流速度保持不变时,温度越高,相对浓度峰值越低,而峰值时孔隙体积比值越高;而在温度相同时,渗流速度越高,相对浓度峰值越低,而峰值时孔隙体积比值越高。温度的变化能够显著影响含水砂层中悬浮颗粒的迁移过程,在升温时,与对照组相比,相对浓度值及悬浮颗粒浓度均有所下降,且变温时间越早,相对浓度值及悬浮颗粒浓度下降幅度越大。温度变化时穿透曲线存在着滞后现象,且小颗粒对温度变化更为敏感。温度变化可以通过改变流体黏性、吸附作用、颗粒动能及表面电势等影响悬浮颗粒在含水砂层中的运移过程,且主控因素随试验条件的变化而改变。

In order to study the effect of temperature on the particles transport in saturated sand,a self-developed sand layer transportation,deposition testing system was adopted,and two kinds of tests(i.e.,transport tests of particles in porous medium under different temperatures,and transport tests of particles in porous medium under variational temperatures)were conducted.Four size compositions and four typical temperatures(i.e.,5℃,15℃,25℃and 35℃)were adopted in our study.The results shown that,when the flow rate is constant,the peak of relative concentration will decrease with the temperature increases,while the pore volume at the peak of relative concentration will increase.Meanwhile,the peak of relative concentration will decrease with the flow rate increases,while the pore volume at the peak of relative concentration will increase.The change of temperature can affect the process of particles transport in porous medium observably.Compared to the contrast group,the relative concentration and the concentration of particles will decrease when the temperature increases,and the falling range will increase as the change of temperature get earlier.We also find a hysteresis phenomenon in the breakthrough curves when temperature changes,and the smaller particles are more sensitive to the change of temperature.Water viscosity,absorption,kinetic energy of particles and surface potential can all affect the transport process of particles under the effect of temperature,while the main controlling factor will change as the test condition changes.