The Causes and Prevention Measures of Water Inflow at Cross Passage Located in Sandy Gravel Layers and Constructed by Artificial Ground Freezing

Taking the construction of artificial ground freezing of cross passage located in sandy gravel layers as analysis case, the effect of thermal properties of soil, in addition to design parameters and construction measures, on the width, as well as the closure time and the average temperature, of frozen bodies were analyzed. It shows that the sensitivity of width of frozen bodies on heat conductivity is greater than on the heat capacity and water content. The space between freeze pipes play a significant role in the closure of frozen bodies. As a result, much attention should be paid to the precision control of the starting position and inclination angle of the freeze pipes in the AGF construction. The sensitivity of freeze pipe dimensions is also investigated, and there may be a small benefit to increasing the diameter of the freeze pipe. The construction defects of thermal insulation material and freeze pipes positioning could affect substantially the closure of the frozen bodies at the intersection of shield tunnel and cross passage, which results in the water inflow when the opening and excavating of shield segment start.