Soil arching in unsaturated soil with different water table

Soil arching above support structures with different water tables may be different. A series of trapdoor tests are carried out to research the effect of water table on soil arch. Displacement of sands and soil pressure on trap door is obtained from test results and the influence of grain size and trap door width have also been considered in the model test. It can be concluded that the limit influenced range of water table on soil arching is two times width of trap door. When water table is less than two times width of trapdoor, the increase of water table can enlarge the height of soil arching and enlarge the soil pressure on trapdoor due to the weaken of soil arching in unsaturated soil. And when water table is more than two times width of trapdoor, the soil arching is wholly in saturated soil and it can't be affected by the change of water table. Calculation method of soil pressure on trapdoor with different water table is obtained based on results of mode tests. The method can be used in the calculation of soil pressure on support structure under unsaturated soil.