Bearing Mechanism And Design Method Of Pile-Reinforced Earth Composite Foundation

According to the present notion, composite foundation could be classified as two types: the horizontal reinforced body and the vertical reinforced body, which were called single composite foundation. In practice, adoption of just one type often counld not meet the engineering need due to the complexity of practical geological condition and other technical or economic reasons, so the combination of the horizontal reinforced body and the vertical reinforced body was taken into account to solve the problem. Pile-reinforced earth composite foundation was such a new kind of soft soil treatment method developed in recent years. Through the deformation harmony, the respective effects of pile, soil and net were initiated to control the residual settlement or differential settlement.Based on engineering practice, several experimental sections in Shenzhen, Guangzhou, Dongguan,Foshan were investigated , and the design condition,construction,bearing mechanism were analysed, a comparison between the effect of different reinforced cushions was drawn to present the base of design method.Two experimental areas in a highway soft soil ground treatment project in Guangdong Province were designed to compare the design mode of pile- reinforced earth composite foundation and pile-supported embankment. In the experiment, the property of soil arch and the bearing effect of net were also analysed. Finally, the further study on two design mode was carried by FEM.Based on three hypotheses, the formula of pile-soil stress ratio was derived, and the influencing factors of pile-soil stress ratio were evaluated through the analysis of an example.A small-scale model test was designed to analyse the load distribution between the pile and the soil under the embankment.The influence of several design parameters, which include fill height, pile cap size, reinforced cushion, and compression modulus of the soil under the pile end or between the piles, on the pile-soil stress ratio was investigated. The construction of the embankment and the residual settlement of the soil between the piles were simulated to analyse the load distribution between the pile and the soil during the process. In addition, the stress changes, settlement, internal force of the net were also simulated by FEM.Finally, the conclusions drawn from the practical experiment, theoretical analysis and model test were combined, based on which, a design method was presented. The construction technology and the detection procedure were also summarized .The design method was used in two practical cases.