In this paper, a new approach based on the demand-capacity model is developed for hydraulic design of granular and granular-cum-geocomposite drainage layers in pavements. The demand is given by the intensity-duration curve obtained from the Intensity-Duration-Frequency curve, which is geographic location specific and corrected for climate change. The capacity curve corresponds to critical infiltration rates and critical durations for a drainage layer which is influenced by the hydraulic and geometric characteristics. The design is acceptable if the capacity curve exceeds the demand curve. The design framework is illustrated for typical geometries of highway pavements with three granular gradations and three geocomposites. Based on the developed framework, hydraulic equivalence is defined and evaluated for the drainage layers. The permissible reduction of granular layer thickness for hydraulic equivalence is evaluated if geocomposite is embedded in the subbase layer of pavements. For an optimum gradation based on hydraulic and structural characteristics, the thickness of granular layer with geocomposite could be reduced by 30% compared to the granular layer without geocomposite, which showed similar hydraulic performance. The significance of drainage layer thickness with geocomposite is shown based on the demand for storage to satisfy the drainage requirement for rainfall events of high intensities and long durations.

本文开发了一种基于需求容量模型的新方法，用于路面颗粒和颗粒与土工复合材料排水层的水力设计。需求由从强度-持续时间-频率曲线获得的强度-持续时间曲线给出，该曲线是特定于地理位置的并针对气候变化进行了校正。容量曲线对应于临界渗透受水力和几何特征影响的排水层的速率和临界持续时间。如果容量曲线超过需求曲线，则设计是可以接受的。该设计框架展示了具有三种颗粒级配和三种土工复合材料的高速公路路面的典型几何形状。基于开发的框架，定义并评估排水层的水力当量。如果将土工复合材料嵌入到水力当量中，则评估颗粒层厚度的允许减少量路面底基层。对于基于水力和结构特性的最佳级配，与没有土工复合材料的颗粒层相比，具有土工复合材料的颗粒层的厚度可以减少30%，并且表现出相似的水力性能。土工复合材料排水层厚度的重要性是基于蓄水需求来满足高强度、长持续时间的降雨事件的排水要求。