Abstract
Complex interaction mechanism exists between the pile group and soil. To realize the pile-soil load transmission mechanism in detail, the failure pattern of pile groups installed in dense sand considering different pile spacing was investigated by means of laboratory experimental model test and three-dimensional discrete element method. The results suggested that the narrow pile spacing was beneficial to the development of the pile tip resistance, and it enhanced the bearing performance of the pile group at the initial stage of settlement. The pile spacing changed the shaft resistance pattern with modification of the strain energy mechanism released within the subsoil. The pile group with 6b pile spacing had higher composite group efficiency. A joint fan-shaped displacement zone was formed beneath the pile tip for the pile group with 3b pile spacing; this pile foundation presented the block failure mechanism. The sand displacement beneath the cap for the pile group with 6b pile spacing mainly located on the upper part of the piles, the sand displacement around both sides of the piles presented asymmetric, and a relatively independent fan-shaped displacement zone was formed beneath the pile tip.
Highlights
Pile groups are widely used as a deep foundation to improve stability of the residential building, transmission tower, drilling platform, and several other types of infrastructure
In studying pile group-soil interaction, considering the bearing capacity of soil and piles is closely related to the deformation of soil and piles and micromechanical properties of soil. e traditional methods of measuring soil deformation are the punctuation method and grid method in the model test [7, 8], which are suitable for measuring large soil deformation. e number of observation points is limited, and the range of deformation measurement is local
Synthetic transparent soil was adopted to visualize the pilesoil interaction, and the vertical and horizontal soil displacement caused by a sequence of jacked piles was discussed [13]. e influence of pile spacing on the bearing capacity of the pile group and the soil deformation near the pile tip was analyzed with the help of particle image velocimetry (PIV) technology [14, 15]
Summary
Pile groups are widely used as a deep foundation to improve stability of the residential building, transmission tower, drilling platform, and several other types of infrastructure. Many researchers have been studying the bearing capacity, settlement, failure pattern, and transmission load mechanism of the pile group by means of theoretical analysis, model test, and numerical simulation, and they have achieved considerable progress [1,2,3]. With the increase in computing power, the numerical simulation technology of the particle flow code based on the discrete element method (DEM) has been applied in the Advances in Civil Engineering study micromechanism of pile foundation. Duan et al [16] used the discrete element method to compare and analyze the bearing characteristics of cast-inplace piles and driven piles, and it has been found the different distribution patterns of shaft resistance and tip resistance and the driven pile presented a better bearing performance in the pile load test. We designed a geotechnical test device and applied the noncontact deformation testing method to examine the bearing performance, sand displacement field, and shear strain field of pile groups with different pile spacing. e test results have been verified by a three-dimensional discrete element model, which was used to study the pile group’s load transfer characteristics and sand stress change law
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