Engineering Characteristics Of Limestone Residual Red Clay In Upper Reaches Of Wanjiang River And Its Influence On Slope Stability

Limestone residual red clay is a branch of clay.It is widely distributed in the upper reaches of the Wanjiang River.During the construction and operation of the project,the limestone residual red clay slopes are often damaged,causing great economic losses and hidden dangers.Relying on the Tongling section of the Shanghai-Chongqing Expressway,this paper selects typical limestone residual red clay soil layers as research objects,conducts experimental research on residual red clay engineering characteristics,and studies on influencing factors and analysis methods of slope stability to clarify the residual red clay slope instability Internal mechanism.First,in the limestone residual red clay outcrop area,an in-situ expansion test,field crack investigation,and crack expansion test under dry and wet cycling conditions were carried out.The promotion of crack development has laid a foundation for subsequent research.Second,taking the original limestone residual red clay sample as the research object,the basic physical and mechanical tests such as moisture content test,density test,particle analysis,and direct shear test were carried out to obtain the basic physical and mechanical parameters of the limestone residual red clay;In addition,indoor swelling tests,including free swelling test,unloaded swelling test and charged swelling test,were compared with in-situ tests to verify that the limestone residual red clay has a certain swelling property,although it did not meet the standards for swelling soil However,weak expansion and fissure properties have an important impact on the degradation of mechanical properties under environmental influences.Then,the red matrix of the limestone residual red clay was separated from the white texture,and X-ray diffraction and electron microscopy scanning tests were performed.The test results showed that the white texture contained more clay minerals than the red matrix.The reason is that the residual red clay particles of limestone belong to the irregular aggregate particle structure.The mass ratio of white texture in limestone residual red clay is defined as the texture ratio.Direct shear tests were conducted on the remodeled samples with different texture ratios.The intensity decreases accordingly.Finally,based on the experiments,FLAC3D software was used to simulate limestone residual red clay slopes with different slope heights,slope ratios,anilox ratios,physical and mechanical parameters,and crack rates.The parameters and slope safety factors were obtained.The relationship between the factors and the stability of the slope was understood.