METHOD FOR FOUNDATION SOIL PILE TESTING Russian patent published in 2021 - IPC E02D1/00 

FIELD: construction.

SUBSTANCE: invention relates to construction, namely to methods for static pile load testing. Method for testing the soil foundation by a pile includes applying an impressing force to a model pile, continuously increasing at a constant speed, determined depending on the diameter of the pile and the physical properties of the soil, synchronous recording the impressing force, the time of its application and the pile settlement with a step of 0.005 mm of the pile settlement, breaking the dependency graph of the model pile settlement velocity rate on the impressing force into three sections according to the pile average settlement rate in each of them and calculating the bearing capacity of the working pile according to the value of the impressing force at the end of the 2nd section of the graph. On the lateral surface of the model pile, a vertical soil deformation meter is placed relative to the lateral surface of the pile at the level of the middle of the first engineering-geological element from the soil surface, composed of clay soil, where resistance to the probe penetration at a speed of 5 mm / min during static probing, carried out before the pile test, changes cyclically, and at the same level at a distance of 1-2 diameters of the pile from its axis, a depth mark is placed. Additionally, the vertical deformation of the soil relative to the lateral surface of the pile and the vertical displacement of the depth mark are recorded synchronously with the registration of the pile settlement at a pitch of 0.005 mm of the pile settlement, and according to the measurements, the acceleration g₁, mm / kPa2, of the pile settlement is calculated according to the given dependency. Cycles of change in the rate of the pile settlement are distinguished, setting their boundaries according to the last value of the pile settlement acceleration as g at g <0 in each i-th cycle of change in the pile settlement rate, where i is the number of the cycle of change in the pile settlement rate, the minimum value of the pile settlement rate is determined on the descending branch of the cycle of the pile settlement rate (at g <0), and the maximum value of the pile settlement rate on the ascending branch of the cycle of the pile settlement rate (at g≥0). Distinguished are the values of the soil vertical deformations relative to the lateral surface of the pile and the vertical displacements of the depth mark, synchronous to the burst of the pile velocity settlement rate, determined according to the given dependency. The first burst of the pile settlement rate is taken as the beginning of the 2nd section of the pile settlement rate dependency graph on the impressing force and as the beginning of the formation of the first shear and cleavage crack in the soil foundation, the length L_cr, m, of the projection of the trace of the shear and cleavage crack on the horizontal plane is calculated and taken for the horizontal size of the pile foundation. Additionally, the position of the beginning of the crack of shear and cleavage on the lateral surface of the pile is determined according to the given dependency.

EFFECT: increased reliability and accuracy of determining the place and time of forming the shear and cleavage crack in the soil foundation caused by the pile settlement during its loading, required to assess the dimensions of the pile foundation.

1 cl, 1 dwg