Research And Application Of Two-pile Composite Foundation In Highway's Soft Soil Subgrade

With the rapid development of our country's economy, the construction of highways developed so fast, and problems involved in soft foundation treatment stood out. What's more, because of the the complexity of deformation mechanism and the diversity of its influencing factors, foundation deformation law and treatments of mountainous soft soil has become an important topic.After learning the project " research and demonstration project on guizhou province of Guizhou mountainous area highway soft foundation treatment key technology ", on the basis of the existing research of soft soil foundation, the paper analyzed and summarized the definition, the distribution and the methods of soft soil in Guizhou. It reviews the forming condition of composite foundation and basic theory, then proposes the length pile composite foundation and the formation of the applicable condition, studied the length of pile composite foundation reinforcement mechanism, and reviews the length of pile composite foundation research situation; it studied the length of pile composite foundation bearing capacity and settlement design theory, and put forward the length of pile composite foundation bearing capacity and settlement calculation mode; PLAXIS finite element method was established by length of pile composite foundation under stress and settlement of flexible load finite element model, the length of the soft pile crisscross decorates CFG pile composite foundation of pile type gravel pile length, long, pile spacing and cushions selected changes PLAXIS numerical simulation using the simulation analysis method of composite foundation settlement of pile soil stress, summarizes the pile foundation and soft combination of rigid pile and flexible pile, it is concluded that the force transmission characteristics of rigid pile and flexible pile length, pile spacing and the reasonable cushions selected scope. The reasonable scope of these parameters for practical engineering with the rigid long piles of flexible short pile composite foundation according to the optimization design of the settlement control provides reference basis.The results of the research of provide theoretical basis for further application of length of pile composite foundation, it do good for improving the quality of guizhou province highway pavement extending pavement life and is of great practical value.