Horizontal drains are widely used for control of pore pressure in slopes and retaining structures. Control of groundwater levels is a critical requirement for economic design
The design of these drains is typically guided by experience and observed performance. Design charts are available covering a range of conditions presented in the form of improvement in factor of safety for slopes. The paper presents relationships for design of drain spacing and length to achieve target pore pressures with a slope or behind a retaining structure. Analytical methods were used to develop the design relationships presented and comparison with published results are presented.
The need for monitoring to check performance is discussed.