适于数值模拟的三维工程地质建模方法

3D engineering geological modeling method suitable for numerical simulation

数值模拟已成为工程地质、岩土工程领域的重要工具,然而目前该技术还普遍存在定性效果好而定量程度偏低的弱点。计算模型难以真实地反映复杂的地质实际与工程实际是影响计算结果可靠性的重要原因之一。为了提高数值模拟中地质建模的效率与可靠性,在边界表示法的基础上,提出了一种适合于数值模拟的三维工程地质建模方法。该方法先构建模型的统一线框架,线框架由若干简单弧组成。以线框架为约束,对原始界面进行编辑与重构,保证界面之间的无缝连接。利用块体搜索方法形成若干由编辑后的界面围成的块体,组成无缝模型。通过界面的复制与平移,解决超薄层块体问题。对于超小夹角块体,将交线两侧的三角形单元适当地绕交线旋转,增大夹角,以提高网格质量。利用网格前沿方法将无缝模型剖分成四面体网格,并结合岩体质量分级,形成适合于数值模拟的计算模型。在某水电工程的坝基稳定性分析项目中,利用该方法为FLAC3D建立了计算模型。

Numerical simulation has been an essential tool in the fields of engineering geology and geotechnics. However, it has a weakness, that is, its results of quantitative analysis are sometimes non-realistic, even if they are often acceptable. One of the reasons resulting in the weakness is that the geological model is not perfectly accordant with the realities of complicated geological and artificial objects. To improve the accordance, a new method of building a 3D engineering geological model is proposed. The method is based on boundary representation and suitable for numerical simulation. Firstly, a unitary wire frame, composed of simple arcs, is built. Secondly, the initial interfaces constrained by the wire frame are modified and reconstructed to ensure seamless connection. Then, using the block tracing method, a sealed model, consisting of blocks surrounded by modified interfaces, is generated. In this model, the problems of ultra-thin and sharp-angled blocks are solved to improve mesh quality. Finally, using advancing front technique, each block of the sealed model is discretized into tetrahedrons; meanwhile, combined with rock mass quality spatial classification, the computing model suitable for numerical simulation is generated. As an example, a 3D engineering geological model for FLAC3D is built to analyze the stability of the dam and the bedrock of a hydropower plant.