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Static pile load tests in laboratory conditions were carried out to study the mechanism of the pile skin and pile base resistance mobilization with settlement and their interactions. The mechanism of the skin resistance at the base is important in the correct interpretation of the pile capacity. Especially in the case of piles shallowly embedded in the bearing layer. In the studies described in this article, high-precision piezoelectric elastic stress maps were used. The tests were carried out on piles with a diameter of 2.5–2.8 cm, and length of 40 cm. Static pile load tests were carried out to measure resistance at the pile base, settlement and change of stress in the soil at the level of the pile base or beneath the pile base were measured. The analysis of stress in soil allowed to investigate the interaction between the resistances of the pile base and skin. The state of stress in the soil close to the pile base, both beneath and above the pile base level was heavily influenced by the simultaneous mobilization of skin and base resistance.

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This article shows the mathematical method to determine the lateral stress on the shaft and toe resistance of pile using the new approach. The method was originally invented by Meyer and Kowalow for the static load test. The approximation curve was used for the estimation of both settlement curve and toe resistance curve of the pile. The load applied at the head of the pile is balanced by the sum of two components: the resistance under the toe of the pile and the skin friction. Therefore, the settlement curve is compilation of two factors: the skin friction curve and the resistance under toe curve. The analysis was based on the verification of the methods using laboratory experiments, that is, static load tests. The results of the research allowed to determine the relationship between parameters of the Meyer–Kowalow curve. On the basis of the relationships, it was possible to determine the skin friction and the toe resistance of the pile. Mathematical analysis of curve parameters allowed to determine the influence of the toe resistance on the settlement.

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.