RESPONSE OF A TYPICAL GRAVITY DAM TO BLAST LOADS

Abstract

Dams are considered among the critical infrastructure, as their incapacitation or destruction may result in heavy loss of life and property. The objective of this dissertation is to investigate the response of a typical gravity dam to blast loads. A two dimensional Discrete Element Model of a typical gravity dam is used in the study. The dam is modeled with two types of boundary condition at base, one with fixed base and other with flexible base with transmitting lateral and bottom boundaries. The Discrete Element Model is validated by comparing the stresses at heel and toe in static condition with the finite element model of the dam prepared in ABAQUS. The fundamental periods of vibration given by two methods are found to be in good agreement. Blast loads are estimated as per IS: 4991-1968. Blast cases are considered on upstream side and downstream side of the dam with empty reservoir and full reservoir condition. Parametric study is carried out by performing dynamic time history analysis for two charge weights of explosives and varying the stand-off distance ranging from 5m to 70m at an interval of 5m. The results of the analyses conducted indicate that displacement at crest increases under the influence of the foundation flexibility. The response of the dam decreases exponentially with increase in stand-off distance, since the response of the dam is proportional to the energy contained in blast induced impulse. The dam is more vulnerable to the underwater blast on the upstream and sliding towards downstream cannot be ruled out in case of high intensity blast