Research Of High-speed Railway Soft Soil Composite Foundation’s Mindlin Solution And Settlement Characteristics

High speed driving requires a high smoothness and high stability of the base form,Thus requiring embankment settlement after construction a strictly controlled within a certain range, Therefore, the deformation control is the key to the design of embankment. modern railway construction Experience has shown that Embankment Settlement mainly include elastic deformation of subgrade surface when the train running, the accumulation of subgrade subsidence caused by Long-term traffic (plastic deformation) and subgrade Embankment and Ground subsidence due to compression; Passenger Dedicated always set CFG pile composite foundation in soft soil area to reduce subgrade settlement, And this foundation calculation method of settlement is an important factor on engineering design and construction.paper combines Beijing-Shanghai express railway Liyao and Fengyang test section Pile Testing,for passenger dedicated line soft soil CFG pile composite foundation, take advantage of engineering actual measurement and Axial force of pile and loading tests and pile-soil stress ratio. Combined with Mindlin theory analysis and calculate single pile and pile group composite foundation reinforcement area and the substratum settlement. Through the research of above aspects, Obtain the following conclusions:(1) Soft soil CFG pile composite foundation settlement can be divided into the reinforcement area settlement and the subjacent settlement. Exploit composite modulus method to calculate reinforcement area settlement,according Boussinesq solution to calculate the additional stress, calculating composite foundation reinforcement zone composite modulus by area weighted method, calculation method is simple and the results are realistic; comparison of different calculation methods and combine soft soil CFG pile composite foundation load characteristics that obtained Mindlin theory is more suitable for Calculate the subjacent additional stress and settlement of soft soil CFG pile composite foundation pile and pile groups.(2) The main stress type of Lee kiln test section CFG pile composite foundation is friction, and main stress type of the Fengyang test section of CFG pile composite foundation is tip bearing capacity. The reason is that the soil between piles with a high strength composite foundation load balancing is relatively low; the longer length of pile pile composite foundation load balancing is more; the larger the pile spacing composite foundation pile load balancing lower.(3)The paper use Mindlin theory to calculate soft soil CFG pile composite foundation the subjacent settlement under single pile or two piles centers or four piles centers.After comparing and analysis the settlement we get that settlement increase with the increasing number of piles and the pile farther away from the pile computing center the smaller the effect on the settlement at the center.