Study On The Evolution Of Soil Pressure And Stability Of Coarse-grained Soil Fill Retaining Walls Under Vertical Coal And Heavy Rainfall

Coarse-grained soils have good engineering properties and are widely available,and have become an important embankment filler in highway traffic engineering.In recent years,heavy rainfall events have occurred frequently in China,and engineering accidents often occur in coarse-grained soil embankment retaining walls,which have brought great economic losses to the country.In this paper,by changing the maximum particle size d_max of the specimen to 10mm,20mm,40mm and 60mm respectively,a model test under static and dynamic load forces was designed to study the influence of the maximum particle size on the hydrostatic characteristics of the soil pressure of coarse-grained soil;by carrying out rainfall tests on the model retaining wall of coarse-grained soil fill,the displacement of the retaining wall,the soil pressure behind the wall and the water content were studied under the action of strong rainfall,and finally,with the help of The effects of rainfall intensity and load on the stability of the retaining wall were investigated with the help of numerical simulation software.The main research contents and results are as follows:（1）By changing the maximum particle size,four groups of coarse-grained soil specimens with different particle gradations were designed and tested in soil pressure models under different static loads.The coarse-grained soil static earth pressure coefficient K₀ decreases with increasingσ’_v during loading,and the K₀-σ’_vrelationship for coarse-grained soil under low stress is established based on the previous study;under the sameσ’_v action,the static earth pressure coefficient K₀ decreases with increasing the maximum particle size d_max,and K₀ is a logarithmic function of d_max.Based on the established K₀-σ’_v relationship,a calculation model reflecting the coupling effect ofσ’_v and d_max on K₀ of coarse-grained soil under low stress was established.（2）The results show that when the loading frequency is the same,the increase in peak load causes the vertical pressure and soil pressure to increase approximately linearly at different depths,and the trend of increase decreases with the increase in particle size;the vertical pressure and soil pressure are smaller with the increase in frequency when the peak load is the same.（3）A model test of coarse-grained earth retaining wall was designed and carried out to study the effects of load and heavy rainfall on the displacement of coarse-grained earth retaining wall,soil pressure behind the wall and volumetric moisture content.",with the increase in the number of rainfall cycles behind the wall soil pressure to reach the maximum time decreases and there is a hysteresis;volume water content of the law of change is‘rapid growth-stable-rapid decline-tend to stabilize’;the displacement of the retaining wall gradually increases with the rainfall cycle;the influence of rainfall on the earth pressure coefficient K₀ of the soil behind the wall is small,and the influence of load on the earth pressure coefficient K₀ of the soil is large,and K₀ decreases with the increase of load.（4）The numerical model of coarse-grained soil fill retaining wall was established by numerical simulation software to study the influence of rainfall intensity and load on the stability of coarse-grained soil fill retaining wall,and the results show that:under the same rainfall duration,the rainfall intensity has a greater influence on the stability of coarse-grained soil fill retaining wall,and the safety coefficient of retaining wall shows a sudden drop first and then recovers slowly after the rainfall stops;under the same rainfall conditions,the safety coefficient of retaining wall decreases at a faster rate as the load increases.Under the same rainfall conditions,the coefficient of safety of the retaining wall decreases at a faster rate as the load increases.