基于三维力学模型的大范围自然边坡稳定性概率评价方法

 为了对大范围自然边坡的滑坡危险度进行评价，利用GIS技术作为平台，把传统的三维极限平衡力学模型耦合到概率统计分析框架中，提出一个基于边坡单元的定量评价的新方法。在把大面积的研究区域划分为边坡单元后，采用一个基于GIS的三维力学模型计算每个边坡单元三维安全系数的分布。假定此分布遵从对数正态分布，再采用一个可靠性指标计算该分布中小于某临界值的概率，并以此来定量评价该边坡单元的整体滑坡危险度。此方法同时也可以求得各边坡单元的最危险滑动面的位置和规模。开发一个专业GIS系统来完成所有的计算分析步骤，本系统能够快速、高效地完成大量的三维建模与安全系数计算，综合了三维力学模型与概率统计方法的优点，实现了对地形地质条件复杂多变的大范围自然边坡的稳定性定量评价。通过对日本一国道边坡应用对本方法的有效性进行了验证。

A 3D DETERMINISTIC MODEL BASED PROBABILISTIC METHOD FOR LANDSLIDE HAZARD ASSESSMENT OF LARGE MOUNTAINOUS AREA

In order to quantitatively assess landslide hazard of a large mountainous area，a slope-unit-based probabilistic methodology that involves a three-dimensional(3D) deterministic model coupled with a geographical information system(GIS) is proposed. An automatic method is developed to divide a study area to slope units. For each slope unit，a GIS-based 3D slope stability analysis model is applied to the calculation of the distribution of 3D factor of safety through a Monte Carlo simulation for the unknown shape of slip surface. Assuming the resultant 3D factor of safety follows a log-normal distribution，a widely-used reliability index is then used to quantitatively evaluate the probability of unsatisfactory performance of each slope unit. At the same time，the location and the magnitude of critical slip surface(s) can also be identified by minimizing the trial 3D factor of safety. An advanced GIS is developed to efficiently implement all of the computational procedures. This method integrates the advantages of both 3D deterministic model and probabilistic method，which can quickly and efficiently complete a large number of 3D modeling and calculations of factors of safety，realizing the quantitative assessment of a natural mountainous area with complexly topographical and geological conditions. The effectiveness of the proposed method has been tested in a practical application to a landslide-prone road slope area in Japan.