Case Study of Dynamic Responses of a Single Pile Foundation Installed in Coal Ash Landfills using Effective Stress Analysis and EQWEAP

Abstract

Coal ash continues to be a major production of energy generated material and its use are predicted to increase. The disposal of coal ash has become an important issue when not only chemical but also physical and engineering characteristic of the coal ash is necessary to be researched. The large quantity of disposal of coal ash is even more complicated to handle. This paper is focused on researching dynamic behaviors of coal ash soils obtained in a landfilled field in north Taiwan and also the dynamic interaction of a single pile foundation sitting in the landfills. An effective stress analysis, firstly, was adopted for examining seismic response of 4 m height single pile with 10 m depth into the ground, of which soil parameters in the constitutive model was confirmed basis of stress path and stress- strain relationship of the coal ash soils. Then, the pile response was researched again by EQWEAP. This paper found out that 1) when the pore water pressure reached 40 kpa at around 5sec, the coal ash landfill liquefied, 2) the movement of pile foundation became larger after 5sec, 3) the nonlinearity of the soils resulted in reducing responded horizontal acceleration of the soils at different depth after 5sec. It also showed that both numerical codes were applicable of reproducing pile responses in this an extreme weak coal ash in this study.