电渗法加固粉土的可行性研究

    Feasibility study on silt reinforcement by electro-osmosis consolidation

    • 摘要: 粉土的渗透系数一般为6.0×10-5~6.0×10-4 cm/s,介于软黏土与砂土之间,电渗法对渗透系数较小的软黏土具有较好的加固效果,对砂土的加固效果较差,但其对粉土是否有效,尚无明确定论。通过两组试验,对电渗加固过程中的电流、排水量与排水速率、含水率等进行分析,并在试验结束后,采用SEM扫描电镜获取土体微观结构变化图像,利用PCAS测定加固土体的微观结构参数,定量分析与其对应的宏观参数间的关系,探究电渗法加固粉土的可行性。结果表明:自阳极注入浓度为1 mol/L CaCl2溶液时,土体的排水速率与排水量均得到有效提升,且电渗的有效加固时间延长。然而,两组试验土体的承载力和抗剪强度均未得到显著增长,且加固均匀性较差。因此,电渗法对粉土的加固效果稍微欠缺,如若仅考虑缩短粉土的加固时间,可以与真空预压、堆载预压等方法联合使用。

       

      Abstract: The permeability coefficient of silt ranges from 6.0×10-5 to 6.0×10-4 cm/s, which is between that of soft clay and sand. Electro-osmosis consolidation has a good reinforcement effect on soft clay with small permeability coefficient and poor reinforcement effect on sand, but there is no clear conclusion whether it is effective for silt. Two experiments were conducted using electro-osmosis consolidation, and the current, water discharge and discharge rate, water content were analyzed. SEM was used to obtain the image of microstructure change of the silt, the microstructure parameters of the consolidated silt was measured by PCAS, and the relationship between microstructure parameters and corresponding macroscopic parameters were quantitatively analyzed to explore the feasibility of electro-osmosis consolidation for silt. The results showed that when the concentration of 1 mol/L CaCl2 was injected from the anode, the water discharge and discharge rate of the soil were effectively increased, and the effective reinforcement time of electro-osmosis was prolonged. However, the bearing capacity and shear strength in both groups were not significantly increased, and the consolidation uniformity was poor. Therefore, electro-osmosis consolidation was slightly insufficient for the consolidation of silt. If the only objective is to shorten the silt consolidation time, it was considered to use electro-osmosis method in combination with vacuum preloading, surcharge preloading.

       

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