| Most of the eastern and northwestern regions of Guangdong are middle and low mountains and hilly areas,with less land and more people.Most of the houses built by residents are built by cutting slopes.According to incomplete statistics,there are more than 300000 houses built by cutting slopes in the province.The prevention and control of geological disasters caused by this is very difficult,which is the main cause of casualties in recent years.In view of this,this paper relies on the 2020 national territory scientific research project of the Department of natural resources of Guangdong Province,"Research on prevention and Control Countermeasures of artificial slopes in key mountainous counties(cities)in Guangdong Province",to study the influence of the slope and slope height of artificial slope cutting on the stability of different types of parent rock residual soil slopes in Guangdong mountainous areas.First of all,a comprehensive investigation on the geological hazards of the residual soil slope in Guangdong mountainous area is carried out.According to the statistical results,the residual soil slope has six basic characteristics.For example,the residual soil slope is generally composed of residual Deluvial layer,completely weathered layer and strongly weathered layer;In terms of the failure mode of residual soil slope,the arc like failure in landslide failure is the main failure mode of residual soil slope in Guangdong mountainous area.The results also show that the geological disasters of collapse and landslide induced by slope cutting and building houses mainly occur in the residual soil slopes of magmatic rocks(accounting for 48.97%)and clastic rocks(accounting for 33.1%);The height of artificial slope cutting is mainly distributed in the range of 5m～15m;The cutting slope is mainly distributed between 50 ° ～70 °;The slope cutting shape is mainly linear.Secondly,four kinds of residual soil slopes in Guangdong mountainous area that are prone to geological disasters caused by slope cutting and building houses are investigated,which are sandstone,quartz sandstone,mica quartz schist and granite residual soil slopes respectively;Then the residual soil of four different parent rocks is sampled,and the basic physical and mechanical tests are carried out on the soil samples.The test results show that the residual soil of sandstone,quartz sandstone and mica quartz schist is named silty clay,and the residual soil of granite is named sandy clay.The shear strength of the four residual soils is greatly affected by the soil moisture content,and the natural moisture content is within the range of strong strength water sensitivity.Therefore,the soil strength in the natural environment is strongly affected by the water state.Then,the soil water characteristic curve test of residual soil samples is carried out by using Fredlund SWCC soil water characteristic curve pressure plate instrument,and the soil water characteristic curve fitting model of residual soil in Guangdong mountainous area is studied by using SWCC modified model based on the test data.The results show that the most suitable model for sandstone residual soil,quartz sandstone residual soil and granite residual soil is Fredlund &Xing 1 modified model,Mica quartz schist residual soil is Fredlund&Xing 2 modified model.Then,the calculation formulas of basic parameters of soil water characteristic curve are derived,and the air intake value,residual saturation and residual matrix suction of four residual soil samples in Guangdong mountainous area are calculated by using the fitting results of SWCC modified model.Finally,based on the investigation and statistics results of geological disasters of artificial slopes in Guangdong mountainous areas,the numerical simulation schemes of artificial slope cutting and Mei Yu and rainstorm are formulated.Using the indoor test results of residual soil samples and the numerical simulation analysis method,the influence of artificial slope cutting slope and slope height on the stability of different types of parent rock residual soil slopes is studied;According to different types of parent rock residual soil slopes,the limits of artificial slope cutting gradient and height are put forward,which has a good reference value for the prevention and control of geological disasters caused by artificial slope cutting in Guangdong mountainous areas in the future. |
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