Pile bearing analysis based upon ultimate values of toe and skin resistance as well as their mobilization with settlement

Krzysztof Żarkiewicz,M Kaszynska

doi:10.1051/matecconf/201928403011

Krzysztof Żarkiewicz, M Kaszynska

Open Access

https://doi.org/10.1051/matecconf/201928403011

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Abstract

The main task of pile foundation is the reduction of settlement and ensure the safety of the building. These two factors are in strongly relationship. In practice pile load capacity is calculated based on ultimate resistances including factor of safety. The load-settlement relationship is non-linear, so it would can happen that despite the applied load (several times smaller than ultimate pile load capacity), the settlement exceeds the allowable value, and in consequently it might cause damage of the structure. In the paper the method of determining ultimate resistances and mobilization of these resistances with settlement was presented based on the static pile load test results. The proposed method can be applied in pile load capacity verification.

Highlights

Pile is a part of deep foundation which allow to transfer load on the subsoil to deeper and stiffer layers in case of insufficient shear strength of upper layer
In common used method pile load capacity is calculated based on ultimate values of toe resistance and skin friction
The ultimate load is the sum of ultimate toe resistance and skin friction

Summary

Introduction

Pile is a part of deep foundation which allow to transfer load on the subsoil to deeper and stiffer layers in case of insufficient shear strength of upper layer. In the case of designing only for safety factors, it may turn out that the safety factor was very large, the high settlement of the pile can lead to structural damage The allowable settlement of the pile may be differing from 30 mm, and it depends of building requirements, but mostly 30 mm meets these requirements Both the piles have the same value of ultimate load equal to 5 MN, but at the designed load can be observed different settlement. It proves that while determining pile load capacity have to be taken into account bearing capacity and allowable settlement of the pile

Ultimate pile load at failure

Ultimate toe resistance of the pile

Ultimate skin friction of the pile

Mobilization of toe and skin resistance with settlement of the pile

Practical approach of the analysis

Conclusions