Abstract: The inclined drain hole is an economical and effective measure to drain the groundwater from slopes. However, the effect is often poor, and the phenomena of no groundwater flowing through, and fast siltation is very common. To further solve these issues, this paper analyzes and discusses the technical methods and principles in the design and construction of the inclined drainage holes in detail based on a rich waterside slope of an expressway. Otherwise, it also explained the design parameters, drainage hole construction requirements. Finally, the two batches of drainage holes were compared in terms of borehole parameters, spatial locations and actual drainage effect. The results show that the hole length and the spatial position of inclined drainage holes are key factors that influencing the drainage effect. Therefore, when designing the drilling parameters, the bore hole position should be arranged in the low elevation position such as the slope toe in combination with the geological investigation data, and the drilling should be extended below the groundwater level or into the aquifer.

Key words: Inclined Drainage Hole, Design Parameters, Weep Hole Length, Spatial Position