Research On Red Sandstone Soil Strength Characteristics And Subgrade Slope Stability Under Dry-wet Cycle

Rainfall infiltration and evaporation,changes of groundwater level and seasonal temperature changes are typical dry-wet cycle phenomena in the natural world,while the hot and rainy climate in the southern regions has accelerated the dry-wet cycle of the soil.In this paper,the red sandstone soil of Ganzhou was the research object,and the dry-wet cycle simulation was carried out,and then the shearing test was carried out to study the effects of different initial dry density and water content on the strength of red sandstone soil under the dry-wet cycle.The changing law of the shearing strength of red sandstone soil under the different times of wet-dry cycles,as well as the shear strength indicators such as cohesion,internal friction angle and the change of the drywet cycle period,ABAQUS finite strength reduction method was used to calculate and analyze the deformation and stability of the subgrade slope.The main research contents and results are as follows:(1)Through a series of indoor tests,some basic physical indicators of red sandstone soil have been measured,which provided basic data for subsequent experiments and the setting of analyzing and calculating parameter.(2)Simulating the effect of dry-wet cycles on red sandstone soil.The effects of different dry density,water content,and vertical pressure on its shearing strength characteristics were discussed and analyzed with shearing tests..(3)The shearing strength indexes of red sandstone soil change with the dry-wet cycle effect,and there is a good exponential relationship among red sandstone soil cohesion,internal friction angle and cycle number(4)The effect of the dry-wet cycle on the stability of the subgrade slope shows an obvious two-stage characteristics,namely,fast first and then slow,which is greatly affected by the previous two cycles,and slows down gradually after the fourth time,eventually stabilized.(5)The stability of subgrade slope is significantly affected by the initial dry density and water content.The greater the initial dry density,the higher the slope stability,and the greater the initial water content,the lower the slope stability.Moisture content has a greater influence on the deformation of subgrade slopes.When the moisture content is low,the deformation zone begins to produce local deformation from the foot of the slope.With the increase of water content,the deformation of the slope extends from the foot of the slope to the interior of the slope body.