Double Pipe Freezing Test And Optimal Layout Of Freezing Pipe Under Groundwater Seepage

The existence of groundwater flow will have a negative impact on the freezing effect of artificial stratum.Based on the actual engineering parameters,a large-scale seepage controllable freezing similar model test is designed,the double tube freezing test under different seepage velocity is carried out,and the formation law of temperature field under seepage is obtained.The test results show that the development trend of freezing temperature field without seepage is that the temperature decreases first.When the temperature decreases to the steady state,the temperature fluctuates in a small range and maintains a stable state.When the groundwater velocity is 3m/d,the temperature drop rate of freezing temperature field decreases,and the temperature drop rate in the upstream area of water flow is most affected.When the groundwater velocity is 6m/d and 9m/d,the freezing temperature field is affected by large velocity seepage.The temperature drop rate is further reduced,the freezing in the upstream area of the water flow is seriously disturbed,and the freezing temperature field in the upstream area of the water flow is quite different from that in the downstream area.The temperature in the upstream area of the water flow is significantly higher than that in the downstream area.In the 12h-24h and 24h-36h time periods,the diffusion rates in the frozen area at the symmetrical axis of the two freezing pipes are 25.58mm/h,25.68mm/h and 10.97mm/h respectively at the corresponding groundwater velocities of 0m/d,3m/d and 6m/d;2.02mm/h?9.23mm/h?29.20mm/h?Based on the governing equation,the Hydrothermal Coupling numerical model is established.According to the results of model test,the accuracy of the numerical model is verified.Based on the freezing project of Libi mine,the numerical model of the original freezing scheme is established.According to the calculation results,three optimization schemes are further proposed:adding reinforced freezing pipe,adding grouting water blocking curtain,and adding reinforced freezing pipe and grouting water blocking curtain at the same time.The results show that when the groundwater velocity is less than 9m/d,the three optimization schemes can reduce the freezing circle time.When the groundwater velocity is greater than or equal to 9m/d,the optimization scheme of strengthening freezing pipe and grouting water blocking curtain is added at the same time,and the freezing circle time is shorter than the other two optimization schemes.When the groundwater velocity is 6 to 11 m/d respectively.The freezing wall crossing time of the original scheme is 51,69,92,104,137 and 176 d,and the freezing wall crossing time of the optimized scheme is 38,48,52,54,57 and 59 d,which is shortened by 13,21,40,50,80 and 117 d compared with the original scheme,which provides a reference for similar high velocity formation freezing engineering.Figure 60 Table 5 Reference 82...