Методика расчета устойчивости стенок скважины в слабых глинистых основаниях

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The study is aimed at developing a methodology for calculating the stability of walls of boreholes in soft clay bases during the bored pile installation, as well as determining the criteria for maintaining the geometric integrity of the borehole. As a result of the study, leading to clearly-defined requirements for the geometric and strength characteristics of the casing with the prescription in the design documentation and further implementation at the construction site, a reduction in cost indicators for the installation of bored piles is obtained. The presented methodology demonstrates the necessity of applying casing prior to drilling a bore-hole and, if applicable, for calculating the amount of compressive pressure for selecting the cross section according to the geometric and strength parameters ensuring geometric integrity. In the course of the study, the soil mass around the borehole was examined along with a determination of critical radius of the soil to specify the loss of borehole wall stability. Next, the geometric shape of the unstable soil, its weight and, cor-respondingly, pressure at any point on the outer surface of the casing was determined. The conducted mathematical experiment allows the introduction of a criterion for possible casing application in pile borehole drilling, as well as justifying the assumption concerning a relationship between the geometric characteristics of the borehole and the physicomechanical characteristics of the surrounding soil mass for the subsequent installation of the bored pile.