砂-结构界面剪切机理及细观行为演化研究OA北大核心CSTPCD

[Objective]Roughness and particle size are the key factors affecting the side friction of piles in sandy soil,and explo-ring their effects on the macroscopic mechanical properties and microscopic shear mechanisms of the interface is of great signifi-cance.[Methods]Using the improved direct shear equipment,the macro shear behavior and internal change mechanism of the interface between steel and sand considering the influence factors of the groove width and particle size are studied.The evolution law of interface microscopic behavior was studied using PFC software.[Results]The result show that the interface peak shear stress of fine sand and medium sand group increases with the groove width,while that of coarse sand group increases first and then decreases.Under the different relative size relationships between texture width and sand particle size,the interface shear mechanism is closely related to sand-sand shearing,grain-groove interlocking and grain angular blocking.The friction angle of smooth interface decreases with the particle size,while the friction angle of rough interface is basically proportional to the particle size.The coordination number and the range of particles affected by interface shear increase with the particle size.The larger sand particles appear force chain fracture near the interface in the middle and later stages of the test.[Conclusion]Groove design can significantly improve the shear strength of the interface,and the pile surface with rough groove is more conducive to exerting the bearing capacity of the pile in medium and coarse sand soil foundation.