Compression Thickness Under Long Piles Of High Speed Rail-Way Bridge

High speed railway needs high quality of stability and regularity, and strict requirements of settlement control is asked. The settlement calculation for long piles of high speed rail-way bridge is in significance. Thickness of compression layer plays an important role. The rational determination of compression layer thickness can improve settlement calculation, so can rational ground treatment be taken to control the settlement and post-construction settlement.Based on the 9 piles in the group piles foundation of 3 piers at the DK240 work point in the northern segment of Jing-Hu high speed rail-way, through theoretical calculation, field investigation, and Plaxis 3D Foundation finite element analogy, following conclusions can be seen:In the field investigation, the method of "cooperating test using single point settlement gauge and level settlement gauge" is proposed, coming over the disadvantage that single point settlement gauge can't be anchored in rock, making full use of single point settlement gauge and level settlement gauge, allowing settlement monitor of long group piles in deep soft soil layer. The compression layer thickness is obtained by measured data.The calculation model is revised and perfected according to the data of settlement monitoring. Compression modulus of deep compressible soil is an important parameter in the settlement calculation. A formula of compression modulus on natural situation by depth of soil layer is put forward. By FEM the compression thickness is Obtained.The result in field investigation is compared to the calculation methods of specifications and FEM. It's conserved to calculate the compression thickness by strain control method from the specifications, and the stress control method at the condition of 10% stress's ratio is proposed.