【作者】 张伟；

【导师】 荣传新；

【作者基本信息】 安徽理工大学 ， 建筑与土木工程（专业学位）， 2021， 硕士

【摘要】 地下水流的存在会对人工地层冻结效果产生不良影响。本文基于实际工程参数,设计了一套大尺寸的渗流可控的冻结相似模型试验,开展了不同渗流速度下的双管冻结试验研究,得到了渗流作用下温度场形成规律。试验结果表明:无渗流作用下,冻结温度场的发展趋势均是温度先降低,当温度降低至稳态时,温度在较小幅度内波动,温度维持稳定状态。当地下水流速为3m/d时,冻结温度场温度下降速率变小,水流上游区域温度下降速率受影响最大。当地下水流速为6m/d、9m/d时,冻结温度场由于受大流速渗流作用。温度下降速率进一步降低,水流上游区域冻结受干扰严重,并且水流上游区域与水流下游区域冻结温度场差异较大,水流上游区域温度明显高于水流下游区域温度。在12h-24h与24h-36h时间段内,对应地下水流速0m/d、3m/d、6m/d时在两冻结管对称轴位置处的冻结区域扩散速率分别为 25.58mm/h、25.68mm/h、10.97mm/h;2.02mm/h、9.23mm/h、29.20mm/h。基于控制方程,建立了水热耦合数值模型,根据模型试验的结果,验证了数值模型的准确性。以里必矿冻结工程为背景,建立了原冻结方案的数值模型,根据计算结果,进一步提出了增设加强冻结管、增设注浆阻水帷幕以及同时增设加强冻结管和注浆阻水帷幕共三种优化方案。使用数值模拟手段,对这三种方案进行对比分析,结果表明:当地下水流速小于9m/d时,三种优化方案均可减少冻结交圈时间。当地下水流速大于等于9m/d时,同时增设加强冻结管和注浆阻水帷幕的优化方案相比其他两种优化方案冻结交圈时间更短。当地下水流速分别为6至11 m/d时。原方案的冻结壁交圈时间为51、69、92、104、137、176 d,该优化方案的冻结壁交圈时间为38、48、52、54、57、59 d,相比原方案缩短了 13、21、40、50、80、117 d,为类似大流速地层冻结工程提供参考。图60表8参82更多还原

【Abstract】 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更多还原