Study On Deformation And Load Characteristics Of The Rigid Net Grid-Small Pile Group Composite Foundation Under Rectangular Footings

Rigid Net Grid-Small 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-Small Pile Group Composite Foundation strengthening technology has broad prospects of development.Combined with Pile-Net composite foundation, this article describes deformation and load characteristics of the Rigid Net Grid-Small Pile Group Composite Foundation under rectangular footings. Furtherly, the author tried to build and calculate the three-dimensional model of Rigid Net Grid-Small 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, bedding cushion's thickness and footings mode. The tension reinforcement net and rigid net grid transfer part of load to small pile group, is conducive to the bearing capacity of the pile and deep soil layer. Homogenization effect of deformation difference cause of the rigid net grid, reduces the differential settlement of the foundation surface. Restriction of lateral displacement on top of the pile shift reduces the pile (especially the side pile) shear deformation, but also conducive to reducing the shear deformation of foundation.Pile spacing has great impact on the characteristics of the composite foundation. The smaller the pile spacing, the lateral displacement of pile, the pile shear absolute value and the side friction resistance of pile becomes smaller; bedding cushion's thickness on the characteristics of composite foundation plays a coordinating role. Along with the cushion layer thickness, pile lateral displacement reduced gradually, cause reinforced cushion stiffness contributes to uniform load transmission; The lateral displacement of pile as the footing stiffness decreases, as the footing spacing increases.