Deformation Characteristics And Control Techniques Of Ultra High Fill Embankment On Steep Slopes

Construction of high grade highways in mountainous areas with complex terrain and terrain conditions,often encountered a considerable number of high fill,deep excavation subgrade.This paper aims at the sand soil embankment filling of Xia-Rong Expressway extension Project(Zhangzhou Section),first,various tests including sieving,moisture content,bulk density,compaction,in-situ direct shear,Muronai Nao and indoor rapid compression were carried out,and the strength and compression characteristics of the sand soil filler in the bid were revealed in detail.At the same time,the "BBM constitutive model" which can reflect the influence of soil matrix suction is selected,and the constitutive parameters are calibrated.The feasibility and correctness of the constitutive model applied to the sandy soil in the engineering is verified in FLAC3D numerical platform.Further,numerical simulation is carried out for the construction and rolling process of super high embankment.The settlement and lateral displacement of embankment are mainly concerned.Compared with the field monitoring results,the deformation characteristics and control technology of super high embankment on steep slope foundation are discussed.The main work done and the main conclusions are as follows:(1)through field direct shear test and indoor fast compression test,it is suggested that the BBM constitutive model is adopted for the sand soil filling in the expansion project of the Xia-Rong Expressway extension Project(Zhangzhou section Al).The constitutive parameters are as follows:c is 4.86kPa,? is 26.57,? is 0.015,Es is 15MPa.(2)compared with moisture content,compaction degree has a more significant effect on compression modulus,and the compression modulus of sand packing increases approximately linearly with the increase of compaction degree.(3)The cohesion of sandy soil increases with the increase of compaction degree,increases first and then decreases with the increase of moisture content,and the cohesion is more sensitive to compaction Moisture content.(4)The internal friction angle of sand soil increases with the increase of compaction degree,and the change range is small with the increase of water content,the influence is negligible.(5)Similar to the classical"MCC constitutive model",when the soil sample in the "BBM constitutive model" is damaged,the main stress difference and the initial deformation modulus will also increase with the increase of confining pressure.Reflects the pressure of soil.(6)Compared with the classical "MCC constitutive model",when the soil sample in the "BBM constitutive model" is destroyed,the main stress difference is slightly larger than that of the former,indicating the existence of the matrix suction,Shear strength.At the same time,the higher the moisture content,the smaller the difference of the main stress when the soil sample is damaged,which shows that the matrix suction decreases with the increase of the water content.(7)The numerical simulation of the dynamic deformation characteristics of steep slope embankment using FLAC3D shows that the settlement and horizontal lateral displacement of embankment increase with the increase of embankment filling height.The settlement along the height of embankment The maximum displacement occurs in the middle part of the embankment with less settlement at the top and bottom of the embankment.The maximum settlement and displacement along the width of the embankment occurs in the middle part of the embankment with less settlement on both sides of the embankment.The horizontal lateral displacement along the height of the embankment occurs most frequently The middle part of the embankment has less displacement at the top and bottom of the embankment.