Direct Shear Test Of Soil-Concrete Interface Of Energy Pile

The study of mechanical properties of the interface between soil and concrete structure is an important subject in geotechnical engineering.With the vigorous develop ment of large-scale civil engineering construction,the problem of interface between soil and concrete structure becomes more and more important.It is more and more urgent to study the interface between soil and concrete structure and clarify its interaction mechanism and law.The problem of soil-concrete interface involves consideration of many factors.Analyzing and clarifying the influence trend and mechanism of various factors on the mechanical properties and deformation properties of soil-concrete interface has important guiding significance for the future engineering development.With the increasingly serious environmental pollution,energy pile as a new technology emerges.Through the cleaning of geothermal energy,Sustainable use of energy is of great engineering significance.As a bearing pile foundation,the influence of temperature effect on the bearing capacity of pile foundation may cause potential safety hazards in engineering construction and have higher requirements for the installation and application of energy pile.In this paper,a large-scale direct shear instrument for pile-soil interface developed by our research group is introduced.The experimental study on sand and clay under corresponding working conditions is carried out.By controlling the normal load(100kPa,200kPa,300kPa),sand particle size distribution and the heating grade of thermal conductive fluid(10,50,70?),18 sets of unidirectional direct shear tests were carried out on the sand-concrete interface.The shear stress-shear displacement curve,shear strength,normal displacement-shear displacement relationship of the interface were analyzed through the tests,and the traditional contact was also analyzed.The applicability of the plane hyperbolic model and the exponential model is analyzed.Based on the exponential model,the composite exponential model is improved by considering the stress softening to improve the fitting degree.Through controlling normal load(100kPa,200kPa,3 00kPa),initial moisture content of clay(5%,10%,15%,20%)and heating grade of thermal conductive fluid(10,50,70?),39 groups of one-way direct shear tests of clay-concrete interface were carried out.The temperature gradient distribution,water transport and shear stress changes in clay layer under different working conditions were analyzed and summarized.The shear test of clay-concrete interface is simulated by ABAQUS finite element simulation software.The distribution and variation of shear stress and shear strain in the process of shear of interface are analyzed.The shear test of interface is simulated considering different normal load conditions and thermal conductivity temperature.