Деформації малоповерхових кам'яних будівель, спричинені нерівномірними осіданнями ґрунтів основ фундаментів

Abstract

The article presents the results of a study of the causes of progressive uneven deformations of buildings using real examples under conditions of wetting of the foundation soils with water. It was found that the subsidence of the base soils in the area under the sole of the foundations led to the appearance of deformations in the form of cracks in the brick walls of the building with an opening width of up to 24 mm. Analysis of the obtained data allowed us to establish that the cause of uneven deformations is the deterioration of the deformation parameters of subsidence of loess soils of the foundations due to flooding by leaks emergency damage to water supply systems. Laboratory studies of loess soils of the base revealed a significant change in their physical, mechanical and subsidence properties. The moisture content of the base soils increased 14.3% to 26.1%, which is 82%. The results of laboratory studies showed that during the period of operation of the building, the following quantitative changes occurred in the bearing layer: the modulus of deformation of the loess base decreased by 100%; with an increase in the moisture content of the loess base soil, the average value of the angle of internal friction decreased by 20%, and the specific adhesion decreased by 114%, the porosity coefficient decreased by almost 38%. Analysis of the parameters of subsidence of loess loams of the base within the building outside the humidification zone and in the humidification zone shows that the reduction in the quantitative values of relative subsidence ranges 165% at low loads to 66% at a load of 0.3 MPa. During the period of exploitation of the building, the bearing layer of loess soil was compacted. At the same time, the value of the initial subsidence pressure increased compared to the design value. The increase in the quantitative value of the initial subsidence pressure reaches 55%. Laboratory studies of loess soil samples when moistened with water of different temperatures showed an increase in the parameters of relative subsidence with increasing water temperature. At the same time, the increase in the value of relative subsidence reaches almost 25%. Laboratory studies confirmed the assumption about the influence of the temperature of the moistening water on the acceleration of the process of subsidence of the base soil and, as a result, deformation of the building in the form of cracks on its walls.