Assessment of liquefaction and extent of ground improvement for rehabilitation of Ash Pond

Abstract

Rehabilitation of abandoned ash ponds for the establishment of various engineering structures like an industrial power plant, housing colonies, parking slots, warehouses, etc., requires a detailed analysis of ash deposits. Borehole data and other basic lab tests are the primary sources for any geotechnical investigation. In some cases, this bore data may not be available or unreliable for the present site condition. A non-invasive method developed known as MASW (Multi-Channel Analysis of Surface Waves) finds to be suitable for collecting shear wave velocity, which can be related to the N value. MASW test was done on four different sites of the ash pond of Gujarat State Electricity Corporation Limited (GSECL). An empirical correlation between shear wave velocity (Vs) and SPT N value was used directly based on past investigations for ash ponds in India. Liquefaction Analysis was done for different earthquake magnitudes (Mw 5.5, 7.7, 8.7) for earthquake Zone III. Stone Column in a triangular grid was adopted for the reduction of voids to stop the liquefaction. The stone column's proper design was done to rehabilitate the abandoned ash pond. A complete methodology was presented to use for any other thermal power plant in any earthquake zone of India.