关键词: 冻结法凿井, 冻结壁, 水热耦合, 优化设计, 数值计算

Abstract: In order to solve the engineering problem that the closure time of artificial frozen wall increased or even failed to overlap under the action of groundwater with large flow rate, considering the effect of groundwater on the artificial freezing temperature field, the method of encrypting the freezing pipes in the upstream area of the water flow was proposed to optimize the freezing scheme. The hydrothermal coupling mathematical model was constructed which was based on the apparent heat capacity method, and the rationality of the mathematical model was verified by large physical model tests. Based on the mathematical model and the design parameters of a freezing scheme in a shaft of Huainan mining area, the optimization effects of the seven optimization schemes were analyzed by numerical calculation. The optimization effect was analyzed: Under the action of groundwater with a large flow rate, the freezing effect of the upstream position of the freezing pipe arrangement circle is a decisive factor affecting the closure time and thickness of the entire frozen wall. After encrypting the freezing pipes in the upstream position, the spacing between adjacent freezing pipes is reduced, and the cold supply in the upstream position was increased, thereby the closure time of the frozen wall in the upstream area was shortened, and the freezing efficiency of the entire frozen wall was increased .when the angle of encryption was 105 , and the spacing of the freezing pipes was reduced to 1 m, the maximum interlacing velocity of the frozen wall reaches 13 m/d, which is 62.5% higher than that was before optimization (8m/d). And corresponding to the same freezing time, the thickness of the frozen wall formed by the optimized freezing scheme was significantly larger than that before the optimization. The optimized design method would provide an important reference for the design of freezing holes in freezing method with large-flow-rate groundwater.