Experimental Investigation on Effects of Water Flow to Freezing Sand around Vertically Buried Freezing Pipe

High groundwater flow velocity is a major challenge in many artificial ground freezing (AGF) projects, especially in groundwater control projects. That condition may be unfavorable for the formation of a frozen body. This study aims to understand the effect of seepage flow on the heat transfer behavior and hydraulic conductivity variation of sand during the freezing process in AGF projects by using a vertically buried freezing pipe. The authors conducted a small-scale laboratory experiment that combined a flow test, freezing process, and infrared thermograph observations of thermal distribution. The authors prepared saturated Toyoura sand and a Toyoura-silica sand layer combination as the heat-transfer medium. The thermal distribution and hydraulic conductivity behavior were investigated by two series of freezing experiments with different sand layers and flow scenarios. Infrared thermograph observation results showed how water affects the thermal distribution characteristic, whereas flow test results showed the relation between hydraulic conductivity and frozen-body development.