Оценка величины относительной тангенциальной деформации

The issue of soil mass stability under external influences, including those arising during the construction of buildings and structures, is evaluated by determining the soil strength characteristics. In engineering practice, this involves determining the shear resistance of the soil at the ultimate stress state. The concept of soil strength is primarily related to ensuring the stability of the soil foundation. When the slopes of the foundations lose stability and collapse, the soil mass shifts one part relative to the other, and therefore the strength properties of the soil are directly related to its shear resistance.

According to GOST requirements, soil is tested under various constant load values until one part of the soil moves relative to the other by more than 10 % of the diameter of the test sample. At the same time, the maximum force that was achieved during the tests is measured.

However, due to the fact that the standard samples tested in laboratory and field conditions have a cylindrical shape, the relative ten percent shear, defined as the ratio of the shear value to the sample diameter, does not determine the required relative deformation value according to GOST. Since the deformation during single-plane shear, similar to compression, affects the entire volume of the sample, the correct assessment of the relative deformation would be the ratio of the shear area to the total cutting area. This aspect is not addressed in the regulatory documents, and the standard formulas do not provide a clear solution to the problem. In the proposed work, methods for calculating the shear area from the linear shear of the movable frame of single-plane shear devices are proposed. An error assessment was performed for the relative shear values caused by the relative tangential deformation using the linear method in comparison with the area method.