Highway Culvert Structure By The Force Model And The Practical Offload

In recent years, with the rapid development of transportation's construction in our country, the highway is extended from the plain area to the mountain area, it led to built more and more high-backfill culverts. In order to ensure the safe using of culverts, it's needed to analyse and calculate the culvert's structure accurately, and the keypoint is how to calculate the vertical earth pressure on the top of culvert. In addition, how to use appropriate measures to reduce the vertical earth pressure on the top of culvert and to ensure the safety and economized of culvert's structure, the research has important significance.Based on the culvert under high-backfill of Xiamen to Chengdu highway project in Hunan province, through field test and using geogrids as reinforced materials in the fill, the vertical earth pressure on the top of culvert is tested and analysed in the condition of with and without reinforced materials in the fill, and the corresponding numerical models are setted up to analyse, the main results of research are as follows:1. Without reinforced materials in the fill on the top of culvert, the results of field test and numerical simulation showed that when the height of fill reached a certain value, the vertical earth pressure is significantly greater than the theoretical value(σ=γH), the theoretical calculation is not safe for the high-backfill culvert's structure.2. The effect factors of vertical earth pressure were analysed, it showed that the slope of gully is steeper, the vertical earth pressure is less; the width of foundation is smaller, the vertical earth pressure is less; the density of fill is smaller, the coefficient of vertical earth pressure is less; the elastic modulus of fill is greater, the coefficient of vertical earth pressure is less.3. With reinforced materials in the fill on the top of culvert, the results of on-the-spot test and numerical simulation are showed that when the height of fill reached a certain value, the vertical earth pressure is significantly less than the theoretical value(σ=γH), the geogrids could be used to reduce the load on the top of culvert. 4. The effect factors of reinforcement load reduction were analysed, it showed that the geogrids are paved more, the vertical earth pressure is less; the separate distance of geogrids is smaller, the vertical earth pressure is less.