LARGE-SCALE MODEL TESTS ON RESISTANCE OF RIVER LEVEE WITH SANDBAG AGAINST OVERFLOW

Extreme rainfall caused huge flood disaster with failure of river levees which is mainly occurred due to overflow. River levees is therefore necessary to have a resistance against overflow. One of reinforcement technology is an armored levee which is reinforced with concrete panels over front and back slope of the levee. However, the armored levee has been collapsed due to overflow after the toe of back slope is eroded and concrete panels on the back slope are flown out. For increasing the resistance of levee against overflow erosion, Kurakami et al. (2017) proposed a new river levee in which a laminar drain layer is set along the back-slope of the levee with geo-gird layer laid inside the levee material. The levee is named as an LDR (Laminar-Drain Reinforced) levee. The fundamental performance of the LDR levee for overflow and infiltration has been confirmed through large-scale model tests with 1m-high river levee. However, it is not easy to construct the LDR levee in general field. In the present study, we propose a new type of LDR levee with maintaining the performance of the resistance against overflow and simplifying the construction process of the LDR levee. For this, we installed sandbag with gravel on the back-slope as drain layer. The fundamental performance of the simplified LDR levee with sandbag has been examined through the large-scale model tests under overflow. The experimental results indicated that the simplified LDR levee can keep the resistance against overflow like the normal LDR levee, showing the fundamental performance of the simplified LDR levee.