从可拓理论在工程地质领域应用出发，首先分析了工程地质领域问题的特点——“等级对关联度的影响效果相同，但等级的取值区间长度可以不同；等级内关联值随取值呈一阶线性变化”；其次根据一个应用可拓理论中物元模型进行工程地质建模的简单特例，将物元模型展开，绘制出关于所有等级的“关联度-等级（影响因素值）”关系曲线，根据曲线与实际现象的不符之处分析模型存在的问题；提出一个新的关联函数计算方程，改进了原关联函数方程与实际的不符之处；最后通过分析改进后的方程曲线，论证改进后方程较符合工程地质领域问题的实际情况。总之，本文分析了可拓理论中的物元模型在工程地质领域中应用存在的问题，改进了物元模型中的关联度计算函数，对可拓模型在工程地质领域中的广泛和正确应用起到了推动作用。

This paper focuses on the applications of extension theory in geological engineering. The characteristics of geological engineering are first discussed, and it is shown that the effect of different grades on the correlation degree is equivalent but interval lengths may be different; and correlation degree is linearly related with effect factor. With a special and simple geological engineering example, the extension matter-element theory is applied and then expanded, and related curves of all grades between correlation degrees and grades (effect factor values) are plotted. The problems are analyzed based on differences between curves and actual situations. A new correlation function is then proposed to improve the differences between the original function and actual situations. Finally, the improved function is shown in agreement with actual situations by analyzing its curves in geological engineering.