Kravtsov V.
https://doi.org/10.35579/2076-6033-2020-12-05
ABSTRACT
The article discusses modern practical approaches to the calculation of pile bases, gives the actual picture of their deformation and loss of stability under the influence of vertical pressing/ pulling loads. It is stated that the currently used methods for assessing the load-bearing capacity and stability of the pile base (theoretical, engineering-practical, numerical), based on simplified idealized models, the theory of solid body elasticity, do not correspond to the actual state, properties and behaviour of dispersed soils under load. This greatly reduces the reliability of the results obtained for them (the difference between the calculated and experimental data reaches 100 %), and therefore they need to be clarified. Therefore, the aim of this work is to improve the accuracy and reliability of calculation methods by taking into account the actual operation of piles in the ground and its properties. Analysis of experimental data showed that the loss of stability of the pile base at the stage of exhaustion of its load-bearing capacity well corresponds to the assumptions and principles adopted in the theory of ultimate soil equilibrium. In this regard, the article offers a theoretical solution that develops the provisions of the theory of the ultimate stress state of soils in relation to the assessment of the bearing capacity and stability of the Foundation of piles. The solution is obtained for the condition of a flat problem when loading a multi-layer base of a pile with a vertical pressing force. In the design scheme, the following basic assumptions are made:
- the loss of stability of the pile base occurs as a result of shifts on the sliding surface of an undisturbed volume of soil in the form of a truncated cone, including the pile, relative to stationary soil;
- sliding surfaces have constant faces close to rectilinear, which are rigidly oriented in space by angles of inclination to the vertical-βi, along the length of the trunk, and αi-to the horizontal, at the level of the end of the pile;
- the maximum normative load on the pile is determined under the condition of the maximum ordinate of the development of the limit equilibrium region zmax = 0.25d, which corresponds to the critical draft sкр ≤ ξ su.
The proposed theoretical solution can be used to develop methods for assessing the load-bearing capacity and stability of both finished and Packed piles of various types, for which partial coefficients of the working condition are established, depending on their parameters, soil properties and manufacturing method.
Keywords: theory of ultimate stress equilibrium of the soil, particular problem of stability of the pile base, sliding surface, shear zone, ultimate draft.
For citation: Kravtsov V. Calculation of the bearing capacity and stability of the base of a vertically loaded single pile by pressing (pulling) force based on the results of soil tests. In: Contemporary Issues of Concrete and Reinforced Concrete: Collected Research Papers. Minsk. Institute BelNIIS. Vol. 12. 2020. pp. 71-85. https://doi.org/10.35579/2076-6033-2020-12-05
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