EPS Load Reduction Technology Application And Numerical Simulation For High Fill Culert

The high embankments are often utilized for highway construction in large topographic mountain areas to cut down the project budget, so lots of high fill culverts are constructed. Since the high fill culvert should burden large earth pressure, the arch culvert has some drawbacks such as large structural sizes, hard to construct and it is more expansive. Using the load reduction technology by placing the EPS (Expanded Polystyrene) slab on top of culvert can produce soil arching effects and reduce vertical earth pressure. The slab culvert can be used instead of the arch culvert which has a lot of advantages such as less material dosage, easy construction, short construction period, and so on.This paper is based on the project of'Application of new concept design method in high fill culvert'. The purpose of this project is to prompt the application of the EPS slab load reduction technology. A high fill highway culvert is designed and constructed by using the EPS slab load reduction technology. Compressive behavior of EPS is researched and diagnosed by soil test in laboratory, EPS load reduction technology is studied with numerical analysis method, and the conclusions are listed as follows:1. Based on the triaxial and uniaxial compressive test, compressive deformation, creep and stress relaxation behavior of EPS were studied under different load velocity and confine pressures conditions. The results indicate that stepped uniaxial test is applicable to simulate the stress and strain behavior of EPS for load reduction technology under high embankment. Furthermore, the formulas between compressive strength with densities and compressive modulus with densities are concluded according to the series stepped uniaxial test that can be used in load reduction designing.2. EPS load reduction technology was used for a culvert in china. The slab culvert was used to replace arch culvert successfully which decresing about half project cost and speeding construction progress. Earth pressure acted on the culvert and EPS compressive deformation were tested at the period of construction, and over 700 days observation have been performed after construction. The distribution of earth pressure and EPS deformation properties are conducted. The observation results show that the slab culvert is in good condition for about two years.3. Soil tests of Drucker-Prager Cap model for soil and Crushable Foam model for EPS were simulated by finite element method (FEM). The selected model is confirmed to be effective according to the comparation of FEM calculation results and laboratory test results. Parameters of material models are modified to increase the accuracy of results obtained form FEM.4.2D FEM model were established to analyze the interaction mechanism between soil and culvert for the unload reduction culvert. The change theory of earth pressure and the main impact factors were obtained. The three dimension stress distribution properties were analyzed for high embankment culvert, which make up the weak point for 2D FEM. A new earth pressure property is proposed with the results of 3D FEM.5. The load reduction mechanics and the main impact factors are concluded from 2D FEM analysis of EPS slab load reduction technology for high fill culvert. The comparative analysis results by placing EPS slab on net span and full placing on culvert indicate that net span placing type is an appropriate method for load reduction. Three dimension compressive deformations with the soil height is obtained by 3D FEM, which can be used to design the depth of EPS along longitudinal direction of the culvert.6. EPS load reduction design coefficient method is established on the basses of field tests results, the EPS load reduction technology application in this paper and the FEM calculation results. The earth pressure and culvert design progress is simplified. To avoid damaging the EPS slab by machine during construction, the pressure and compressive deformation induced by construction load were studied. As a result, simply construction technology is proposed for fill soil on EPS slab.