离子型稀土原地浸矿注液孔周含水率分布的计算模型
Calculation moisture content distribution around injection hole during in-situ leaching process of ion-adsorption rare earth mines
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摘要: 考虑注液孔内积水产生的压力水头在土体中的传递,建立了积水条件下的一维垂直入渗的基本方程;将实测的饱和导水率等效为孔底一维入渗的饱和导水率,采用积水条件一维垂直入渗的基本方程计算注液孔孔底中心垂向的含水率分布;假设入渗过程中形成的湿润锋簇上的含水率增量相等,根据累积注液量等于湿润体内的水分增加量,确定湿润锋簇中各湿润锋的位置,结合注液孔孔底中心垂向的含水率分布,确定湿润体内含水率分布。在龙南足洞某稀土矿山选择一场地较平整的矿块进行单孔注液试验,在注液孔周布置4个测点,采用FDS-100水分传感器记录测点位置在入渗过程中不同时刻的含水率,与模型的计算值进行比较,结果发现,4个测点的实测值与计算值相关系数基本在0.900以上,模型的计算误差均在10%以下,满足工程误差要求,说明此方法能较为准确的计算出注液孔内水分入渗过程及湿润体内含水率分布。Abstract: Ponding in injection hole will generate pressure head in soil surface. Considering the transfer of the pressure head through the soil, a basic equation for one-dimensional vertical infiltration under ponding is developed. The measured saturated hydraulic conductivity is regarded to be equivalent to that of one-dimensional infiltration, and the distribution rules of moisture content along the vertical direction of the injection hole of the hole bottem is calculated by the basic equation for one-dimensional vertical infiltration under ponding. Assuming that the moisture content increment is equal in each wetting front which is formed during infiltration process, and according to that the cumulative liquid injection is equal to the moisture increment in the wetted region, each wetting front is obtained. Considering with the moisture content distribution along the vertical direction of the injection hole of the hole bottom, the moisture content distribution in the wetted region is determined. A smooth ore block in Zudong rare earth mine in China is chosen to perform single-hole injection tests, and 4 measuring points are arranged around the injection hole. During the infiltration process, the moisture contents at measuring points are recorded by FDS-100 moisture sensors. By comparing the values calculated by the proposed model with the test ones, it is found that the correlation coefficient between the calculated values and the requirements is satisfactory. During the infiltration process, the moisture content distribution in the wetted region is calculated accurately by the established model.