SHEAR DEFORMATION OF ROCKFILL MATERIALS IN SMALL WOODEN CHECK DAM

Forest conservation and soil erosion control are an important issue in Japan since 67% of Japan’s land is covered by forests. Recently, various measures have been taken for promoting the use of wood gathered from the thinning of forests. The new approach adopted in Japan is the use of thinned trees instead of concrete as a construction material to build small wooden check dams for the environmental and landscape protections. Wood is renewable, ecosystem-friendly, and available at lower cost, as compared to concrete which causes environmental loading. However, unlike concrete dam, the stability of wooden check dam depends on various factors in which the shear deformation under the actions of earth pressure is an important factor that must be considered in computing stability and in design. In this research, the dam model experiments and large scale direct shear tests are conducted to examine the shear resistance force, internal friction angle, and shear plane of rockfill materials due to shear deformation. It is found that the shear resistance force is twice of the calculated horizontal component of passive earth pressure by the influence of inclination of the wall. The researched result is a basis for designing against the shear deformation of the small wooden check dam.