New Type of Hydraulic Cutoff Walls in Coastal Landfill Sites from H-jointed Steel Pipe Sheet Piles with H-H Joints

This paper shows development and application potential of H-jointed steel pipe sheet piles (SPSPs) with H-H joints on vertical hydraulic cutoff walls used in coastal landfills. The authors have developed a number of technologies such as developing the H-jointed SPSPs and H-H joints for SPSP joint sections aimed at improving performance and widening application areas of SPSPs. Hydraulic conductivity and toxic substances containment effects of the H-jointed SPSPs with H-H joints was evaluated by laboratory hydraulic conductivity tests, and seepage and advection/dispersion analysis, respectively. The H-jointed SPSPs with H-H joints demonstrate a hydraulic conductivity of the order 10⁻⁸ cm/s at 2 m water level difference between the sea and the contained waste. In order to use H-jointed SPSPs with H-H joints as a vertical cutoff hydraulic wall, it is desirable that a hydraulic conductivity of order 10⁻⁸ cm/s is ensured under the condition that penetration is to the lower clay layer.