Breakage Mitigation Method for Culverts under High Embankments Using Eps Geofoam
Many culverts under high embankments were destroyed for the high earth pressure, one effective method is reducing the load on culvert. To reduce high earth pressure and play the role of shear strength of soil, flexible material EPS (Expanded polystyrene)
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BREAKAGE MITIGATION METHOD FOR CULVERTS UNDER HIGH EMBANKMENTS USING EPS GEOFOAM Fenglin Jiang, Anquan Gu Highway school, Chang 'an university, 120 Two ring Road Xi'an 710064, China Many culverts under high embankments were destroyed for the high earth pressure, one effective method is reducing the load on culvert. To reduce high earth pressure and play the role of shear strength of soil, flexible material EPS (Expanded polystyrene) geofoam slab was placed on the top and sides of culvert. Results of get from site test indicate that EPS has great effect in reducing vertical and lateral pressure on culvert. The minimum pressure after load reduction only take on 30 percent ofsoil column weight on the top and 10 percent at the lateral. EPS also can decrease uneven longitudinal settlement of culverts. The results obtained by FEM proved the test results in situ. Using the reduced earth pressure to redesign the culvert can reduce the size of the culvert, avoid destroy of culvert and save the construction cost efficiently. INTRODUCING
Culverts are special structure under highway embankment to drainage water or take as channels which will be set 1 to 3 in plain or 3 to 5 in mountain every kilometer under road and will be take on about 20.6 percent total cost of one road. For high embankment culverts are very common in maintain area in west china, some culvers on which the height of embankment even over 60 meter. These high fill soil produce high load acting on culverts, it's very difficult to estimate the value of earth pressure, the results that conclude from different theory formula sometimes is twice than another, so the structure strength of high fill culverts are different with different theory. Many culvers are designed by underestimate load and result in failure (Gu Anquan, 1960), some culvers adopted over stiffness to burden the high earth pressure lead to waste. Reducing earth pressure on the culvert is effective method to in the high embankment construction; it can reduce the load greatly and make the culvert more safety. EPS geofoam is an ideal material for reducing the earth pressure, after putting EPS geofoam on the top and sides of culvert, for the high flexible property of EPS geofoam, the integral rigid consisted of EPS and culvert is lower than the soil on the sides of soil, positive arching (Vaslestad, et aI., 1993), earth pressure can be reduced greatly. The test in situ identified that the effects ofload reduction are perfectly (Gu Anquan, 2005). EPS MECHANICAL PROPERTIES
EPS geofoam has low densities (10-40kg/m3) and large compress deformation ability.
Typical EPS geofoam with density of30 kg/rrr' stress-strain curve (confined compress test) is shown in Figure 1. Obviously, the stress-strain curve has three stages which include elastic, plastic and harden stage. Initially, the curve obey Hook's law, the stress is proportional to the stain. The elastic limit is reached at 0.02-0.06. With the strain increase over the elastic limit, the curve become calmly, less increment of stress can crease large stra
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