Study On The Application Of The Model Of Backfill Lightweight Soil Retaining Structure In Steep Slope Subgrade

Among the vast territory in China,there are a large number of mountains,which has been an major barrier to the development of economic and transportation.Affected by the impact of the factor of terrain,landform,environment and investment,the problem of constructing fill roadbed on steep slope is often encountered in the construction of highway.In the process of construction of backfill roadbed on steep slope,because of the common backfill with the characteristics of high compressibility and heavy self weight,using the common backfill as the roadbed would cause greater impact on the stability of the slope.With the development of the backfill subgrade engineering,Using lightweight soil as the roadbed has helped solving some problems which are difficult in the past.the Lightweight soi has following characteristics: 1)Lightweight soil has a lighter bulk density,but its strength is still maintained at a high level;2)after solidifying,the self-standing of lightweight soil is very considerable,and its lateral pressure coefficient is smaller.The use of lightweight soil rather than ordinary backfill materials,can greatly increase the stability of the slope,reduce the cost of reinforcement,and with a small volume of retaining structure designed,the economical efficiency of the project can be improved.This research originates from the key scientific and technological project of Henan Province(152102310082),applied research of silt recycled materials based on technique of Light-weight soil,and from science and technology program of Zhengzhou(20130820),the applied research of EPS technique of regenerated light weight soil mixed with silt.In this paper,a highway slope in Shenzhen,Longgang is taken as an example to study the application of the Lightweight Soil-Retaining Structure joint model in the steep slope backfill subgrade.Based on the method of theoretical calculation and numerical simulation,the stability of steep slope roadbed has been calculated.The influences of Lightweight Soil-Retaining Structure joint model and common backfill on slope stability and retaining wall have been analyzed.The main research contents and conclusions are as follows:(1)The acquisition of light weight soil formula and parameters of soil.The experiment was carried out to obtain the physical and mechanical properties of lightweight soil mass,such as elastic modulus,stiffness,internal friction angle and cohesion.(2)Based on the Lizheng and finite element calculation software,the stability on steep slope in the absence of supporting,ordinary backfill,lightweight soil retaining structure under the three conditions has been calculated.In these three conditions,the stability coefficient were 1.41948,0.81605,and 1.316.The theoretical results show: The steep slope was in a stable state in the original state,but it would be in a state of instability under the condition of the general backfill Subgrade,The slope was restored to a stable state again,After its backfill changed into light soil subgrade.Light soil backfill subgrade has great contribution to slope stability.(3)9 typical point positions were selected to analyze the displacement,stress and strain of the steep slope soil under the condition of two kinds of typical backfill and lightweight backfill Based on a kind of finite element calculation software—Abaqus.,The results show that the stress and strain of the common backfill subgrade is smaller than those of the subgrade is changed into a lightweight soil mass.Under these two conditions,the stress and strain values of lightweight backfill soil are less than those of common backfill soil.The maximum stress difference of 9 point positions is 20%,and the maximum strain value is different from 22%.Based on Abaqus,the numerical simulating calculation of retaining wall structure is carried out.The stress,strain and displacement of retaining wall are analyzed.The maximum stress of retaining wall is 165 kPa under the condition of normal backfill soil,which would change into 133 kPa under the condition of light soil.The displacement of the retaining wall is 100.3mm under the condition of case 1,which would change into 13.7mm under the condition of case 2,so that the displacement of the retaining wall is reduced by 87 mm.Through calculation of anti sliding stability coefficient and anti overturning stability coefficient of retaining wall,we find that the anti sliding stability coefficient and anti overturning stability coefficient of retaining wall are 1.45 and 2.51 under the condition of case1.which would be 1.64 and 3.01 under the condition of case 2.Through the study of the application of the lightweight soil retaining structure model and the common backfill in the steep slope backfill subgrade,the joint model has high economic and security in the engineering application,and it is worthy of popularization and application.