No abstract

Surcharge loading, phreatic level decline and other factors cause negative skin friction on the peripheral surface of piles, which increases engineering insecurity. Negative skin friction has been researched deeply by filed, scale and numerical test. However, few studies have considered the influences of drainage boundary conditions on pile settlement considering consolidation of surrounding soils. Based on 1D perfect elasto-plastic model, this paper demonstrates that pile-soil elastic relative displacement at the position of neutral point is zero, and derives a simplified settlement calculation method. Calculation results show that change of neutral point position makes the pile-soil relative displacement not zero. Finally, the proposed method is verified by FEM method and used to analyze the influence of different drainage cases on the pile settlement.

ABSTRACT A novel ternary composite of carbon fiber, nano-hydroxyapatite and polyamide46 (CF/HA/PA46) was prepared by extrusion method. The mechanical properties were characterized and preliminary cell responses were investigated to explore the feasibility of load-bearing bone repair. The results showed that the bending strength and tensile strength were 159-222 MPa and 117-199 MPa, respectively, when the CF content was in the range of 5%-20%. The tensile modulus was 7.7-10.8 GPa. The MG-63 cells with an osteogenic phenotype were well adhered and spread on the CF/HA/PA46 surface. Compared to the HA/PA46 control, the addition of CF into HA/PA46 manifest improved the toughness and had little negative effects on MG-63 cells. The obtained ternary composite has potential as load-bearing bone repair.