Study On The Reinforcement Technology Of Loess High Fill Embankment With Limited Compaction

Currently,China is engaged in the building of powerful transportation country.High-grade highway construction covers all areas in a comprehensive way.High filling is a major engineering problem in mountainous areas.The high fill embankment is often made of local materials,and the natural moisture rate often deviates from the optimum moisture rate.It is always a difficult problem to solve the problem of insufficient compaction caused by poor fill.Geocell,as a kind of three-dimensional geosynthetic material,has significant reinforcement effect and is widely used in the field of embankment.But there are few studies on the high loess fill embankment with limited compactness strengthened by geocell.Therefore,laboratory test,numerical simulation and field monitoring are employed to study the mechanism of geocell reinforcement technology in high loess fill embankment with limited compaction,it provides reference for the design and construction of similar projects.The main research results are as follows:(1)Through laboratory test,measure the parameters of embankment filling and foundation soil,and provide the basis for parameter determination for finite element simulation.The results show that the natural moisture rate(24% ? 28%)of loess filler deviates from the optimum moisture rate(15.6%).(2)According to the practical project,the finite element simulation of the filling process of the high loess fill embankment is carried out,and the deformation control effect of the geocell and its embedding position on the embankment is analyzed.The results show that the settlement of high loess fill embankment is characterized by large embankment center and small two sides,and the maximum accumulated settlement during the construction period is roughly located in the center of 4m embankment filling height;for the middle and lower embankment,the reinforcement has little effect on the settlement control of 0-6m soil fill at the shoulder.Compared with unreinforced,the middle and upper reinforcement reduces differential settlement about 12%?19%;the reinforcement reduces the accumulated maximum settlement by about 250 mm,and reduces the accumulated maximum horizontal displacement by 60 mm.In general,the upper reinforcement is better than the middle reinforcement.The upper reinforcement reduces the settlement of embankment section by 18% ? 20%,the slope horizontal displacement by 13 ? 16%,the middle reinforcement reduces the settlement of embankment section by 11% ? 14%,and the slope displacement by 11 ? 13%.(3)The section settlement and horizontal displacement of high fill loess embankment during construction are monitored.The results show that: the settlement of embankment section increases with the increase of filling height,and the settlement curve of embankment section is in shape of “normal function”;the horizontal displacement curve is in shape of “triangle”,which is about 2m below the platform,and the displacement reaches the maximum;the horizontal displacement of slope of loess high fill reinforced embankment during construction is very small,and the main deformation is vertical settlement;the main factors affecting the deformation rate of embankment are construction technology,rainfall,filling rate,etc.The settlement rate of embankment is reduced from 3 ? 7mm /d to 2mm /d by the embedded geocell,and the uneven settlement of embankment is controlled.The relation between settling rate and filling rate is quadratic function.(4)After the verification of numerical analysis simulation model and parameters,the control effect of different geocell parameters on embankment deformation is carried out.The results show that the deformation of embankment decreases with the increase of elastic modulus,height and laying width of the geocell,but the effect of restriction has its limitation.It is suggested that the optimum geocell with modulus of 500 MPa and height of 150 mm should be selected,and the distance between the edge of the geocell and the embankment slope is 3 m.(5)It is feasible to control the deformation of high loess fill embankment with insufficient compaction by geocell reinforcement technology.