| Numerous studies have shown that the cracks in expansive soil slope play animportant role in seepage and stability. Expansive soils due to its features expandwhen sucking water and shrink when losing water, so the expansive soil moisturecontent changed will produce the expansion and shrink, and repeated expansion andshrink will form cracks, resulting in expansive soil slope shallow landslide,seriously affecting the stability of subgrade slope and cutting slope in highwayengineering building in expansive soil area. Therefore, the research for the cracks inthe expansive soil is particularly important. In order to understand the processes theexpansive soil cutting slope cracks produced, the effect on the stability and seepagefield of expansive soil slope in rainfall condition considering cracks, the law of thegeogrid supporting. It is necessary to carry on system numerical simulation analysisfor these works in order to get the deep-seated law. In this paper, we research theproblem appeared at Ningming part in Nanning- Youyiguan Highway in Guangxi,explain and analysis the problem already appeared and get the law.The main research work and conclusions are as follows：1.Derived through the analysis of the Ningming regional climatic factors,geological factors and hydrological factors, we got the reasons of expansive soilSwell-Shrink Characteristics, summarized and classified the cracks on the slope inthis region, and analyze the extent of the slope cracks developed through the metricsand measurement statistics of cracks;use the GeoStudio software based on asimplified consolidation theory of unsaturated expansive soil to simulate theprogress that the expansive soil emerged after the rainfall and evaporation, andfound cracks appeared certain closing after extended in the whole progress.2. We selected a typical expansive soil slope in Ningming region as the researchobject, research the effect consider the different cracks depth and space, differentrainfall time and rainfall intensity on expansive soil slope seepage field and thestability, the results show that the cracks depth has a great effect on slope seepagefield and stability, while the cracks space had no significant effect on them. Theeffect is more obvious with rainfall extended on the slope seepage field and stability,the rainfall intensity impact on the slope within a certain range, when the rainfallintensity is greater than the saturated permeability coefficient of expansive soil hadno significant effect on them; 3. Aim at geogrid supporting expansive soil slope in Ningming region we carryon the research. First, we used the temperature field instead of the humidity field inthe FLAC3D, analyze thecrackingof expansive soil slope under different geogridsupport conditions, the results show that the geogrid support improve the tensilestrength of the soil can significantly reduce the degree of cracking of the slope;analyze the geogrid force and displacement, and got the law between the geogridparameters and slope; analyze the effect of geogrid parameters on the slope safetyfactor and the slope plastic zone, and the results show that the geogrid support on theexpansive soil slope is effective. |
