Michihiro NAKAMURA

Study on seepage failure using model tests and the confirmation of a new analysis

Satoru OHTSUKA

Recently, we have heavy rain and dike break occurs around the land. So, antidisaster plan for dike break is needed. The cause of dike break is divide into seepage and overflow. The former is slope failuer, boiling by seepage. The later is by erosion.
Experiments about former break case are implemented many times, and analysis method conserned characters of seepage and force is establised by a new analysis method. This method is consists of two analysis methods. One is a finite element analysis of saturated-unsaturated seepage flow to calculate time histories of saturated degree and pore water pressure (suction) distribution in river bank and foundation ground. The other is a rigid plastic finite element analysis to estimate its stability considering strength and seepage characteristics of unsaturated soil.
The validity of the analysis method is confirmed by simulating some model tests which is seepage failure tests and overflow failure tests. In addition, the structure¡Çs effectivity was studied which is using an iron plate for protecting from overflow failure on some model tests.
We obtain below result by the experiment and analysis.
¡ûThe relation between the result of seepage tests and the result of using a new analysis method.
A new analysis method can express the result of experiment if include water channel.
¡ûThe relation between the result of overflow tests and the result of using a new analysis method.
A new analysis method can express the result of experiment if include water channel. (In this case, we only consider the effect of erosion.)
¡ûAbout the structure¡Çs (using an iron plate) effectivity for protecting from overflow.
It was difficult to express the result of experiment when using an iron plate. It is one of an examination items when the future.

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