灌溉对西北干旱荒漠区排土场边坡稳定的影响—以乌海市新星煤矿为例

为了揭示我国西北干旱荒漠化地区的煤矿排土场边坡在灌溉作用下的流固耦合力学机制，采用渗流力学理论与岩土力学理论相结合的方法，引入Darcy定律和质量守恒定律进行公式推导以建立流固耦合分析方法. 以乌海市新星煤矿为例，采用ABAQUS有限元软件构建边坡非饱和土的流固耦合稳定性分析模型，根据植被需水量以及降雨强度选定5、20、45、70 mm/h这4种等效灌溉强度并交叉搭配2、9、15 h这3种持续灌溉时间，形成12套灌溉方案进行数值模拟. 将数值结果与已有试验结果进行对比，结果表明，当入渗水量增加，边坡竖向变形位移、孔隙水压力分布、等效塑性应变以及安全系数均往不利于边坡稳定的方向发展. 当等效灌溉强度为70 mm/h、灌溉持续时间为15 h时，边坡竖向位移出现大幅度增长，安全系数急剧降至1.03. 在满足植被生长需水量的条件下，应控制灌溉强度，采用短持续时间、间隔灌溉，减少坡面径流出现的可能性，同时应做好截排水和坡面防护措施.

Influence of irrigation on slope stability of dump in arid desert area of Northwest China: a case study of Xinxing coal mine,Wuhai

The seepage mechanics theory was combined with the geomechanics theory to reveal the fluid-solid coupling mechanical mechanism of slopes on the coal mine dump under irrigation in an arid desert region of Northwest China. The Darcy law and the mass conservation law both were introduced to derive the fluid-solid coupling analysis method. Taking Xinxing coal mine of Wuhai city as a sample, the finite element software ABAQUS was used to establish the slope stability model of unsaturated soil under the fluid-solid coupling theory. Twelve types of irrigation schemes were used in the numerical simulation by choosing four types of equivalent irrigation intensity (i.e. 5 mm/h, 20 mm/h, 45 mm/h and 70 mm/h) and three sorts of continuous irrigation time (i.e. 2 h, 9 h and 15 h) according to the water requirement of vegetation and the rainfall intensity, respectively. The numerical results were compared with the existing experimental results. Results showed that the four indicators, including vertical deformation of slope, pore water pressure distribution, equivalent plastic strain, and safety factor, developed in the direction which was not conducive to the slope stability when the infiltration water increased. When the equivalent irrigation intensity was 70 mm/h and the irrigation time was 15 h, the vertical deformation of the slope increased significantly and the safety factor decreased rapidly to 1.03. Under the condition of meeting the water requirement of vegetation growth, the irrigation intensity should be controlled, and short duration and interval irrigation should be adopted to reduce the possibility of slope runoff. Simultaneously, the measures of interception and drainage as well as slope protection should be taken.