Finite Element Analysis Of The Rigid Net Grid-pile Group Composite Foundation

Rigid Net Grid-pile group composite foundation emerge as the disadvantages of current strengthening technologies for soft clay foundation. It's a special kind of composite foundation which forms a rigid space frame based on the rigid net Grids and piles. This composite foundation transfers the loads to the rigid grid structure through bedding cushion and tension reinforcement net firstly, the load then were passed to deep clay by piles. Obviously, it will improve the bearing capacity of composite foundation, reduce the post-load settlement, shorten construction period and also significantly reduce the costs of construction by this composite foundation strengthening technology. As a new type composite foundation technology, Rigid Net Grid-pile group composite foundation strengthening technology has broad prospects of development.Combined with Pile-Net composite foundation, this article describes the mechanism of Rigid Net Grid-pile group composite foundation. Furtherly, the author tried to build and calculate the three-dimensional model of Rigid Net Grid-pile group composite foundation by the finite element analysis software of MIDAS/GTS. Finally, the author gave a deeper research on the influencing factors for this new technology, such as pile spacing, pile-soil modulus ratio, the rigid net grid's stiffness, bedding cushion's thickness and tension reinforcement net's tensile modulus.For this Rigid Net Grid-pile group composite foundation, the rigid net grid can reduces piles bending and shear deformation, reduces the settlement and differential settlement of the foundation surface, decreases the ground surface uplift. The rigid net grid's can be equivalent to a rigid platform when the the modulus of rigid net grid is approaches infinity.Pile spacing, pile-soil modulus ratio and the rigid net grid's stiffness done great impact on the deformation of the composite foundation. The smaller the pile spacing, the smaller of the pile-soil modulus ratio, and the greater of the stiffness of the rigid net grid, the settlement of Rigid Net Grid-pile group composite foundation becomes smaller; The bedding cushion and the tension reinforcement net can harmonize the deformation for the composite foundation. The greater thickness of the bedding cushion, the smaller of pile top lateral displacement and the differential settlement while the center of the reinforced area of composite foundation's surface settlement and ground surface uplift are greater; The greater of the tensile modulus of the tension reinforcement net, the smaller of the differential settlement while the pile top lateral displacement and the center of the reinforced area of composite foundation's surface settlement and ground surface uplift become greater.