A Study on Failure Mechanism of Embankment Dams for Irrigation Damaged by the 1995 Hyogoken-Nanbu Earthquake

The objects of this investigation are to examine the following mechanism of embankment dams for irrigation damaged by the 1995 Hyogoken-Nanbu Earthquake; 1) the mechanism and process of collapse for the Idenoshiri-Ike embankment dam using the effective stress earthquake response analysis; 2) the mechanism of upper slope failure for the Sugatadani-Ike embankment dam using the total stress earthquake response analysis as well as the slope stability analysis with seismic intensity. As a result, the following conclusions are obtained for each objects; 1) the mechanism and process of collapse due to liquefaction can be analyzed that the liquefied areas initially occurred at the toes of upper and lower slopes are extended and connected to make flow downward the volume of embankment and that the result of this analysis is consistent with the real damaged situation; 2) the mechanism of upstream slope failure can be explained only with considering the increase of excess pore pressure in the upstream slope, not extending complete liquefaction, using the both analyses