Abstract
A total of 36 groups of sand-concrete interface loading and unloading direct shear tests were used to analyze the mechanical properties of the pile side-soil interface. The test results show that the interface residual shear stress for the same applied normal stress tends to be constant for the rough sand-concrete interface. The initial shear modulus and peak shear stress of the interface both decrease with the degree of unloading and increase with the interface roughness. The maximum amount of interface shear dilatancy increases with the degree of unloading, and the maximum amount of interface shear shrinkage decreases with unloading for the same interface roughness. A pile side resistance-displacement model is established using the shear displacement method. The proposed function considers both the radial unloading effect and modulus degradation of soil around the pile. The effect of radial unloading and interface roughness on the degradation of the equivalent shear modulus is analyzed using a single fitting parameter b. Good agreement of the proposed model is confirmed by applying the direct shear tests of the 36 groups.
Highlights
RESUMEN: Resistencia de la superficie lateral del pilote a la descarga y a la degradación del módulo cortante en suelos arenosos
Extensive effort has been expended to develop theoretical methods to analyze pile side resistance behavior. These methods fall into four categories: (i) the load transfer method (1–3), which uses the pile side load-transfer function to describe the relationship between pile side resistance and pile-soil interface displacement; (ii) the shear displacement method (4–9), which assumes that the vertical displacement of the soil at any point around the pile is only related to the shear stress at this point and consider the vertical displacement of the soil induced by the shaft shear stress as a logarithmic relationship of the radial distance away from the pile side; (iii) the elastic theory method (10–12), which employs the Mindlin solution under the concentrated load in the elastic half-space to calculate the displacement of the soil
If the interface roughness is low, the interface peak shear stress is mainly influenced by the water content of the interface soils rather than the density
Summary
The large-scale direct shear apparatus has some inherent defects, it is frequently used in interface research due to its simplicity in principle and operation. The test apparatus used in this experiment is the large-scale multi-function direct shear test apparatus SJW-200, which is independently researched and developed by Tongji University, Shanghai, China. The test apparatus has a large size shear box with net size 600 mm × 400 mm × 200 mm (length × width × height) and wall thickness of 40 mm. The test apparatus in both the normal and tangential directions is equipped with an advanced. Pile Side Resistance in Sands for the Unloading Effect and Modulus Degradation 3 server and control system; the range of the test displacement and applied load are enough to satisfy the requirements of this paper.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
