PROCESS OF CAVITY FORMATION AND COLLAPSE UNDER VARIOUS HYDRAULIC FORCES WITH THEIR COUNTERMEASURE TO INTERNAL EROSION

Abstract

 The process of internal erosion under various hydraulic forces is studied by the large-scale hydraulic experiment for the purpose of enhancing countermeasure against internal erosion. It is clarified that the direction of hydraulic forces affects the process of internal erosion in which a cavity gradually grows in the sand and abrupt ground subsidence is caused by the collapse of the cavity underneath the ground surface. Lowering of suction accompanied by penetration of water is closely related to the collapse of the cavity. This research also studied systematically geotechnical filter’s deterrent effect of internal erosion so as to improve the prevention method. As a result, it is verified that the geotechnical filter keeps sufficient deterrent effect under strong hydraulic forces if its uniformity coefficient is larger than 3.0 and the median particle diameter ratio is less than 20.