岩土参数模糊隶属函数的构造方法及应用

Constructing method of fuzzy membership function of geotechnical parameters and its application

研究了隶属函数的特点,指出其在主值区间特点上表现为宽域型和窄域型,在过渡带形式特点上表现为突跳式、线性式和非线性式,在函数图形控制点上有最清晰和最模糊点。根据隶属函数的特点和隶属度总和为1的原理,提出了完整隶属函数的构造方式和函数具体形式参数的计算方法。根据岩体力学和模糊综合评判原理,以岩体的稳定性模糊分类为例,证明在不同的原函数条件下采用上述所提方法构造隶属函数,就具体模糊隶属度值而言存在差异,但最后分类结果一致。作为该隶属函数构造方法的应用,考虑岩体单轴抗压强度、吸水软化性、完整性、岩溶发育等地质条件,山地类型、坡地类型等地理条件,建立了西南山区公路岩质类建设场地模糊分类系统,并将该系统应用于某山区公路建设场地的分类,所得分类结果被施工和设计采用。

Based on studies on the characteristics of membership function, it was indicated that its principal interval could be divided into wide domain model and narrow domain model and that there were three types of its transitional zone forms, namely mutation, linear and nonlinear, and there were the clearest point and the most fuzzy point among the reference point of the function graph. According to the characteristics of membership function and the theory of the summation of membership degree equal to 1, the constructing method of integral fuzzy membership function and the calculation method of the parameters were brought out. Based on rock mechanics and the theory of fuzzy synthetical assessment and taking the fuzzy synthetical classification of rock stability as an example, it was proved that although there were differences among concrete values of fuzzy membership, the final classifications were consistent when the membership functions were constructed by different basic functions according to the above method. As an application of this constructing method of integral fuzzy membership function, the fuzzy classification system of rock construction site of highways in southwest mountainous region was established. Some geomechanical conditions, such as uniaxial compressive strength, softening coefficient because of absorbing water, integrated modulus and karst development degree, and some geographical conditions, such as the mountain land type, slope land type, were taken into account in the system. Finally, this system was accepted by the design and construction engineers, and was used to classify a construction site of highways in mountainous area.