ДИНАМИЧЕСКИЙ МЕТОД ОЦЕНКИ НЕСУЩЕЙ СПОСОБНОСТИ СВАИ И РОСТВЕРКА, УСТРОЕННОГО В ВЫШТАМПОВАННОМ КОТЛОВАНЕ

Abstract

The results of the analysis of formulas designed to determine the resistance of piles based on the results of dynamic tests are presented. Their shortcomings have been identified. It has been established that the existing dynamic testing methodology and the formulas used are not adapted to the conditions of the combined pile foundation, in which the grillwork is arranged in a excavation stamped in the near-pile soil. The list of technological operations and the procedure for conducting dynamic tests of a combined pile foundation are defined. It is proposed to use a hollow steel template imitating a stamp to perform the tests. The initial prerequisites characterizing the features of the interaction of the elements of the hammer-stamp-pile-ground system upon impact of a hammer are given, and based on them, the energy balance equations for two shock modes of operation of diesel hammers (without and with fuel supply to the combustion chamber of the hammer) are compiled. Based on the energy balance equations, formulas were obtained for determining the dynamic resistance of the soil, the introduction of a stamp template and piles, upon impact. The formulas take into account the nature of soil deformation during the immersion of the pile and the stamp template, as well as the dynamic parameters of the elements of the hammer-stamp template-pile-soil system (dynamic loads, dynamic deformations, dynamic coefficient of load and deformation). A formula is proposed for determining the static resistance of a pile and a pile grillage in the form of the difference between the dynamic and viscous resistance of the soil, which depends on the speed of movement of the pile upon impact of a hammer.