基于权重因子模型的建筑荷载作用下地面沉降危险性评价

Assessment of Ground Subsidence Hazard Induced by Building Load Based on Weights-of-evidence Model

针对于城市化进程中建筑荷载引发地面沉降的问题,以天津市局部地区为例,应用权重因子模型对其危险性进行了分析和评价。文中根据该区域的建筑物密集程度、建筑的结构和基础形式、土壤物理性质、水文地质条件等基础数据,应用GIS空间分析的方法分别提取了建筑容积率、土壤竖向应力、压缩层厚度、土壤压缩模量、地下水埋深、地下水渗透性六个诱发因子,经过条件独立性测试,将相互独立的因子组合成六种形式,然后,通过统计对比每个因子的权重值进行叠加分析,绘制了危险性分布图,从而进行地面沉降的危险性评价,最后,评价结果通过受试者工作特征曲线(ROC)验证,表明在使用全部因子进行危险性评价的情况下,分析精确度能够达到85.15%,在使用其他因子组合的情况下,分析精度均超过70%,说明这种评价方法具有较高的准确性和适用性。

Taking a case of densely urban areas,Tianjin,China,this paper focuses on the ground subsidence induced by building load with urbanization,and its hazard was analyzed and evaluated based on weights-of-evidence model. Based on a spatial database containing information such as density of buildings,building structure and basis form,soil physics property,hydrology and geology condition,six major factors,building floor area ratio,soil vertical stress,soil layer thickness,soil compression modulus,depth to groundwater and groundwater permeability,which controlling or related to ground subsidence were extracted by GIS spatial analysis method.Tests of conditional independence were performed,allowing six combinations of independent factors to be discussed. Then,the ground subsidence hazard was mapped and assessed by calculated and overlaid each factor＇s weight. Results were validated by receiver operating characteristic（ ROC）.In the case of all factors used,the accuracy was 85. 15%.In the case of other combinations,the accuracy entirely exceeded 70%. Thus,the veracity and feasibility of this method can be showed.