The Method To Calculate Pile-soil Stress Ratio Of The Pile-net Composite Foundation In High Embankment And Application Research

With the rapid development of economy in our country, the size of the highway construction in our country gradually increases. Due to deep digging and high fill building a road in the soft soil area will make the embankment fill too large, but foundation bearing capacity is low. So how to build highway in high fill section of soft soil area became an urgent problem. Pile-net composite foundation has been widely used in recent years, Because it can improve the bearing capacity of foundation soil and decrease the uneven settlement, so it is an effective method of high fill section soft soil roadbed reinforcement. But for the high fill section the working mechanism of pile-net composite foundation is more complicated, It involves the effect of embankment fil、 pile、 earth among pile and reinforcement materials. However high fill section pile-net composite foundation bearing mechanism and the study of the key parameters such as stress ratio of pile-soil is not mature, and it need more perfection. So the paper deeply analyzes the load transfer mechanism on the basis of explicating the mechanical characteristics of composite foundation under high embankment load, then the paper raise a pile-net composite foundation pile soil stress ratio calculation method, main work and conclusions are as follows:(1) The paper deeply analyzes the load-bearing mechanism of high fill section pile-net composite foundation from top to down. Due to the stiffness of pile between the pile and soil under high fill embankment load Pile displacement and soil displacement will be different, the internal force redistribution in the fill. Embankment load will transfer to the pile. In addition, the overall stability and bearing capacity of soil is improved because of restriction in geotechnical cushion layer. In the piles and soil reinforced area load spreads to the surrounding soils through the pile, so it can improve carrying capacity and reduce subsidence.(2) Based on the engineering characteristics of pile-net composite foundation, the paper analysises the soil arching effect of embankment、 soil-net interaction and pile-soil interaction through establishing reasonable mechanical model, then the paper raise the expression of pile-soil stress ratio. Besides the paper deeply study the key parameters of affecting the stress ratio pile-soil. The results show that with the increase of embankment height pile-soil stress ratio of decreases, namely with the increase of fill height pile and soil load distribution tends to be more uniform, but increasing pile spacing pile elastic modulus、 embankment height and the compression modulus will increase the pile-soil stress ratio; Furthermore the increasing of geogrid tensile strength will cause the increasing of pile-soil stress ratio, but the influence of geogrid tensile strength is small.(3) The paper uses the calculation formula of the stress ratio of pile soil to Yu Wuguang wulongquan to LinXiang period of passenger dedicated line, and the result is verified by ADINA numerical simulation software. The result shows that theoretical calculated value with the test is close to measured data and Numerical Simulation Results. Therefore, it can provide a reference for the related design calculation.