Study On Deformation And Stability Of High-fill Soil-rock Mixture Roadbed In Mountain Area

With the extension of high-grade highway to the mountainous area,the high-fill soil-rock mixture roadbed has become a common roadbed type of highway construction in mountainous area.Due to the complex terrain in mountainous areas、the immature construction technology of soil-rock mixture roadbed and so on,it is difficult to control the deformation and ensure the stability of the high-fill soil-rock mixture roadbed.This paper,based on a high-grade highway project in Shiyan,studys the deformation and stability of high-fill soil-rock mixture roadbed by field investigation,laboratory test,roadbed deformation monitoring and numerical simulation analysis.The main results of research are as follows:(1)Large-scale compression test was carried out to study the compression characteristic of soil-rock mixture.The results show that both stone content and water content have great influence on the compression characteristics of soil-rock mixture.the compression characteristics of the soil-rock mixture with stone content 50% tend to be the compression characteristics of the soil-rock mixture with stone content 65% under the condition of low external load while tend to be the compression characteristics of the soil-rock mixture with stone content 35% under the condition of high external load.(2)Electing representative sections to monitor the deformation of high-fill soil-rock mixture roadbed.The monitoring result shows that the horizontal displacement of roadbed slope increases gradually from top to bottom.When the lower part’s filling of the roadbed slope is higher than that of the upper part,the lower part of the roadbed slope will produce the reverse pressure effect on the roadbed.(3)The influence of different factors on the deformation of high fill roadbed is studied.The study shows that the filling height of roadbed,the lateral slope of ground and the compaction degree of roadbed have obvious effects on the roadbed top settlement.The filling height of roadbed,the lateral slope of ground,the compaction degree of roadbed and roadbed slope degree have obvious effects on horizontal displacement of roadbed.Geogrid has little effect on the deformation of roadbed.(4)The influence of different factors on the stability of high fill roadbed is studied.The study shows that the roadbed height,the lateral slope of ground,geogrid and roadbed compaction degree have obvious influence on roadbed stability,while the roadbed slope degree has weak influence on roadbed stability.The influence of the lateral slope of ground and roadbed slope degree on roadbed stability will be limited by the filling height of roadbed,the influence of geogrid on roadbed stability will be limited by the lateral slope of ground,and the influence of roadbed compaction degree on roadbed stability is basically not limited by other factors.Roadbed filling height,roadbed slope degree,the lateral slope of ground,geogrid and roadbed compaction affect the stability of roadbed by influencing the shear stress in roadbed,roadbed sliding force,roadbed sliding surface extension and its own shear strength respectively.