This study investigates the structural bearing capacity and deformation behaviors of micropiles considering various influence factors including the length (L) of micropiles, outer diameter (d) and wall thickness (t) of steel pipes, diameter (r) and spacing (s) of grouting holes, and water cement ratio (w/c) of grout. Multi-stage axial compressive tests were performed on 20 micropiles to obtain their deformation behavior and axial compressive loads respectively corresponding to the cracking of surrounding grout (Pcr), yielding of steel pipes (Py), and global structural failure (Pult). Experimental results reveal that Pcr and Py are respectively 0.20–0.45 and 0.85–0.95 times Pult. In general, Pult decreases with L. Increasing d produces a more significant improvement in Pult compared to increasing t. The influences of r and s on Pult are associated with the weakening of stiffness and strength of the steel pipes. Micropiles with various w/c levels perform similar Pult, whereas their axial displacement at Pult increases with w/c. Under the same L or w/c condition, increasing d leads to an obvious reduction in the axial displacement at Pult. In the existing criteria, the performance of prediction equations for Pult and allowable axial compression load (Pc) was compared and evaluated. Furthermore, several empirical models were proposed to respectively predict Pult and Pc of the micropiles considering the influences of L, d, t, r, s, and w/c and achieve well predictions.
Characterizing Structural Bearing Capacity and Deformation Behaviors of Micropiles under Multi-Stage Static Loading
KSCE J Civ Eng
KSCE Journal of Civil Engineering ; 27 , 3 ; 992-1009
01.03.2023
18 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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