Technical gazette, Vol. 27 No. 6, 2020.
Preliminary communication
https://doi.org/10.17559/TV-20190722102256
Determination of the Pile Stiffness Matrix Based on the Pile Load Test Results and the Effect of Pile Interaction
Petar Santrač*
; Faculty of Civil Engineering Subotica, University of Novi Sad, Kozaračka 2a, 24000 Subotica, Serbia
Nenad Šušić
; Institut IMS Beograd, Bulevar Vojvode Mišića 43, 11000 Beograd, Serbia
Željko Bajić
; Geo Expertd.o.o. Subotica, Adolfa Singera 11, 24000 Subotica, Serbia
Abstract
The paper presents the determination of the elements of the pile stiffness matrix based on pile load test results, made for the needs of modernization of oil refinery for NIS in Pancevo. The tests were carried out on CFA and Franki piles system. However, only the results for CFA piles are shown in this paper. Load tests included axial, tension and horizontal loading. Bearing in mind the geomechanical composition of the terrain and the results of penetration testing (CPT), it has been concluded that the soil resistance can be approximated as a linear function by depth. By approximating the soil by the Winkler model and using the results of the horizontal pile load test, the equivalent gradient of the modulus of soil reaction for the work load level is determined analytically, and then, the pile flexibility coefficients for horizontal load. For vertical load, the coefficient of flexibility is determined directly on the basis of the load-settlement curve. Based on the flexibility coefficient, a matrix of flexibility and a stiffness matrix are determined. The effect of the pile interaction for horizontal and vertical loads was introduced in an approximate way, through the reduction of coefficients of the stiffness matrix. The entire process of determining the stiffness matrix of the pile is illustrated by practical example of a pile group connected by an ideal rigid cap.
Keywords
pile group interaction; pile load test; pile stiffness matrix
Hrčak ID:
248254
URI
Publication date:
19.12.2020.
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