基于空间插值的工程岩体RQD预测方法

作为工程实际中评价岩体性质的重要指标，RQD的应用已相当广泛。但工程岩体中RQD值的分布存在一定的结构性和随机性，因此，通过对特定位置钻探获取的RQD值无法很到位地表达整个空间区域的实际岩石质量。为了弥补这方面的不足，统计学中的空间插值法为此提供了有力的手段。考虑到空间RQD分布存在各向异性，以及在工程坐标系中很难描述RQD分布的结构性，首先计算工程坐标系下已获取RQD值的主要黑塞方向（pHd）；然后构建空间旋转与比例缩放矩阵对其进行坐标标准化处理。在标准化的空间中，引入Kriging插值法，采用变异函数描述RQD在标准空间结构上的变化，建立其空间变异规律的数学模型，并对其进行插值计算；最后将标准空间进行坐标逆变换，实现了对工程坐标系下RQD分布的预测。利用R语言编程将该方法应用于工程实例，结果表明，这种空间插值法能够有效地预测工程岩体中RQD值的分布规律，弥补了局部钻探的局限性。

RQD prediction method of engineering rock mass based on spatial interpolation

Rock quality designation (RQD) index is an important parameter for evaluating the quality of fractured rock mass and this index has been widely used in rock engineering. It is difficult to express the actual rock mass of the whole space region by RQD obtained from geological exploration drilling in specific location because of structural and random distribution of RQD in engineering rock mass. In order to make up the deficiency, the spatial interpolation method in statistics provides powerful means. By considering the anisotropy of RQD spatial distribution and the difficulty to describe the structure of RQD distribution in engineering coordinate system, a standard coordinate system could be established according to the space rotation matrix and zoom ratio matrix after getting the principal Hessian direction (pHd) of geological exploration drilling RQD in engineering coordinate system. Then Kriging interpolation method is introduced. Variation function is used to describe RQD structural changes in standard coordinate system, a mathematical model which is conforming to spatial variation is established and the interpolation calculation is made. At last, the prediction of RQD distribution in engineering coordinate system will be acquired by inverse transforming standard coordinate system. Using R programming language, the method is applied to engineering. The results show that this method can effectively predict the distribution of RQD in engineering rock mass, and make up the limitation of local drilling.