Characteristics Of Road Water Damage And Mechanism Of Slope Failure Caused By Typhoon Rainstorm

China is a country suffered typhoons most seriously of the world, and southeast region is usually influenced by typhoon rainstorm. Every time typhoon rainstorm would cause extensive damage to roads. In recent years, considering economy and highway traffic facilities have a rapid development, the damage submit zooming trend with time. Based on the field investigation of more than 200 road disease spots and the collected information, the water damage forms are classified systematically, and the interaction relation of destructions is analyzed. On this basis, multi-experimental model were constructed to study the effect of rainfall on slope characters of homogeneous and slope with confining stratum. The slope characters including water content, body strain, thrust at front end, surface deformation of slope. In this experiment, water sensors were adopted to detect the water content in slope body on real time; BOTDR for strain in slope body; pressure cell for thrust at front end; FBG for the surface deformation. The characters change laws with time and depth of slope were obtained under rainfall and groundwater. On the basis of previous study, the FEM centrifuge loading method was improved. The results and conclusions were got as following:(1) The water damage forms are classified systematically, which provide basic support to the further study. After comprehensively analyzing on the water damage forms, characters and cause, the point is proposed that the different water damage forms affect each other. So the protective work of water damage should take all the protective measures as a whole system.(2) Under rainfall, the infiltration develops gradually from slope surface to the bottom. In the rainfall infiltration cause, there is a region with a relatively less water content temporarily. Not only rainfall can affect the water content value in slope, but also can affect the morphology of the water content isoline.(3) Under rainfall, the change laws with time of the slope characteristic indexes, including body strain, thrust at front end, surface deformation of slope, are similar. The slope characteristic indexes bring a peak value during rainfall course, when the rainfall effect is extinct, the characteristic indexes value will fall back, and approach a stable value finally. But the difference of the change laws is that, thrust at front end starts changing after the rainfall begins. While the body strain and surface deformation of slope had obvious change after a relatively long rainfall time.(4) Under rainfall, the change laws with depth of the slope characteristic indexes, including water content, body strain, thrust at front end of slope, are similar. The changing of characteristic indexes in the top and upper part of slope is with great range and speed; the bottom and lower part of slope with less range and speed.(5) Under rainfall, the change laws of the slope characteristic indexes in different angle slope, including water content, body strain, thrust at front end of slope, are similar. Compared with less angle slope, the changing of characteristic indexes in larger angle slope is more strong and with a peak value much higher than that in less angle slope; but the rainfall time needed in larger angle slope is more than the less one(6) After the rainfall effect, comparing with the state before rainfall, the force of anti-slide structure in new slope has a great growth, but the force in old slope hasn't obvious differentia. This phenomenon explains that the new slope is easier to fail than the old one under rainfall.(7) The change laws of the slope characteristic indexes with the groundwater effect are similar to that with the rainfall effect, but differentia as following.â‘ The water content change processes are different. Under the rainfall, the water content in the top part of slope changes at the earliest, and the bottom part changes at latest, that is the water content changes from the top to bottom. Under the groundwater, the water content in the rear and bottom part of slope changes at the earliest; the water content changes from the bottom to top.â‘¡Under rainfall, the change in slope occurs after a certain rainfall time, but the change in slope occurs when the groundwater affect the slope, and there is no accumulating time.(8) The effect of the rainfall on the slope with impermeable layer is similar to which on the homogeneous slope, but the rainfall can only affect the part above the impermeable layer.When the groundwater affect the part under the impermeable layer, the part above the impermeable layer can also be affected. As the experiment results show, the thrust at front end, body strain and surface deformation of slope have a great change in the upper part of slope, especially in the top part.(9) By reconstructing the finite element centrifuge loading method realization process, the method is improved. The improved method remedied the defect of the original method, which has the same application value as the finite element strength reduction method.