厚黄土层矿区采动失水引起的地表沉降计算方法

Calculation method of surface subsidence caused by water loss in thick loess mining area

西部厚黄土层覆盖矿区的采煤沉陷具有特殊性。处于地下水位以下的饱和黄土层在开采沉陷过程中产生失水固结变形,将引起地表发生明显的附加沉降。以渭北黄土覆盖矿区条件为模型,根据地下水位下降曲面特征分析了采动饱和黄土层失水固结的土力学机理,提出了采动黄土层压缩量的计算方法。利用随机介质理论建立了采动黄土层失水固结引起的地表附加沉陷变形的计算模型。实例计算表明,开采沉陷区黄土层的失水固结导致地表发生较大的沉陷,这种附加变形增大了地表变形程度和移动影响范围,对地面建筑物的保护造成不利影响。

Mining subsidence in western thick loess covered mining areas has its particularity. Consolidation deformation of saturated loess layer under groundwater level emerges in the process of mining subsidence,leading to obvious additional surface subsidence. Based on the model of conditions in Weibei mining area covered by loess, soil mechanics mechanism of saturated loess layer consolidation is analyzed according to surface features of groundwater level recession. Meanwhile, calculation method of loess layer compression amounts in mining process is proposed. The calculation model of surface additional subsidence caused by consolidation of loess layer is established using stochastic medium theory. Example shows that consolidation of loess layer in mining subsidence area leads to great subsidence, which can increase the deformation extent and movement influence scope. Thus, this additional deformation will bring unfavorable effects to the protection of structures on the surface.