Study On Shaking Table Test Of The Liquefiable Ground Of High Speed Railway Treated By Compacted Gravel Column-Net Composite Foundation

There is large-area saturated silty soil ground along the Beijing-Shanghai high speed railway. The area is located in 7 degree or 8 degree or 9 degree earthquake region, and the ground is liquefiable with the acting of earthquake load. The liquefaction, the lateral flow of the liquefiable ground, and the embankment settlement generated by embankment damage are the main reason for the damage of high speed railway. So we must clearly know the earthquake liquefaction mechanism of saturated silty soil ground; and we can quantitative assessment the influence of earthquake liquefaction for the high speed railway structure. And building one or more economic and appropriate earthquake-resistance reinforcement method is very necessary and urgent.Firstly, the reinforcement design is carried out by compated gravel column-net composite foundation static design theory. Then the shaking table model test was conducted with a geometrical scale of 1:10 using a large-scale laminar shear box to investigate the reinforcement effects of compacted gravel column-net composite foundation on the saturated silty soil ground. According to comparison analysis between the compacted gravel column-net composite foundation model and the undisturbed soil model, we can generalize some results as foliowings:(1) When the soil between piles liquefied with the acting of the test load, the increase of excess pore water pressure can be restrained and dissipated effectively by the compacted gravel column-net composite foundations to improve the anti-liquefaction ability of ground.(2) The settlement of compacted gravel column-net composite foundation model is very small, and the settlement of ground surface and embankment surface is relatively uniform. The result indicates that the settlement of foundation and subgrade can be reduced greatly by the compacted gravel column-net composite foundation.(3) The amplifying of response acceleration induced by foundation liquefaction can be reduced effectively by the compacted gravel column-net composite foundation. (4) The shear displacement of ground can be reduced greatly by the compacted gravel column-net composite foundation to improve the anti-shear displacement ability of ground.(5) The aseismatic property of foundation and subgrade was improved by the compacted gravel column-net composite foundation. Under the condition of 7 degree seismic fortifications, the design meets earthquake-resistant requirements of Beijing-Shanghai high speed railway.