Vibro piles performance prediction using result of CPT

Paweł Więcławski

doi:10.2478/sgem-2021-0024

Abstract

Abstract Vibro piles belong to the group of full displacement piles with an expanded base, characterised by a very high load capacity, especially in non-cohesive soils. The problem is to adopt a reliable method for the determination of full load–settlement (Q–s) curve. A frequent difficulty is the determination of the load capacity limit based on the static load test because the course of the load–settlement curve is of a linear nature. This publication presents the empirical method. It allows direct prediction of a full axially loaded pile settlement curve based on the values of qc cone resistance obtained in cone penetration test (CPT). The advantage offered by this procedure is the accuracy of the obtained limit values in relation to the actual load-bearing capacity as compared to other methods based on soil parameters obtained in in situ testing. An additional advantage is the Q–s characteristics, which enable designing for intermediate values, allowing for the criterion of minimal or equal settlements. The shape of analytical curves was compared with static pile load test (SPLT) curves. This comparison showed large convergences between the analytical and measured curves.

Highlights

In their present form, Vibro piles were implemented as early as in the 1960s
The developed method belongs to a group of direct methods that make use of the results of cone penetration test (CPT) to determine theoretical load-bearing capacities for
The analysis has shown that the obtained values of ultimate load bearing are similar to the results obtained in static pile load test (SPLT) interpretation methods

Summary

Introduction

In their present form, Vibro piles were implemented as early as in the 1960s. They are installed by driving in a steel pipe with a closed end using a diesel or hydraulic hammer. Pile designing frequently makes use of the results of in situ testing These are primarily the parameters determined based on a cone penetration test (CPT), dynamic probe testing and testing using dilatometer and pressuremeter [3,4,5]. Load-transfer functions method enables the evaluation of entire range of settlement curves using the results of CPT [9, 12,13]. The idea of transformation functions is, to determine the course of the pile settlement curve to the previously calculated bearing capacity. This curve is usually a hyperbola from the starting point up to a conventional limit value.

Paweł Więcławski

Concept of theoretical curve Q–s for Vibro piles

Procedure for determination of theoretical Q–s curve based on CPT results

Application of procedure for design needs

Findings

Summary