COMPRESSION OF THE CLAY SOILS OF NON-DESTRUCTED AND DESTRUCTED STRUCTURE

Abstract

Clay soils have their structural links according to their geological conditions. Compression increases when the soil structural lines are destructed. Even if the density of the soils of distructed structure reaches the density of natural soils, though they get deformed differently under loading. Sometimes it is necessary to have equivalent compression of the soils of destructed and natural structure in construction. The article presents mathematical dependency on how to count a porosity factor of the soils of destructed structure, with its help relative deformations under a given loading come up with relative deformation of natural soils, using dependency of compression porosity factor of structurally rigid soils upon loading in a semi-logarithmic scale. Experimental research into Lithuanian limnoglacial clay soils has showed that increase in the assessment of the initial porosity factor is followed by an increase in difference between the compression of non-destructed and destructed soils. Experimentally obtained and calculated (according to formula 15) results show that, for example, under the loading of 0,2 MPa, decrease in the assessment of the initial porosity factor is followed by a decrease in difference between the assessments of the initial porosity factor of destructed structure, giving deformations equivalent to those of natural soils. The difference which occured after experimentally obtained and calculated results were compared-from 2% to 10%. The decrease in difference shows that an increase in soil density is followed by a decrease in sensitivity of destructure of its natural structure. The initial porosity factor of the soils of destructed structure, calculated according to formula (15), enables us to have deformations equivalent to those of natural soils and it is provided for the loading used in formula (15). Changes in loading will be followed by changes in the assessment of the initial porosity factor calculated according to formula (15). The increase in loading is followed by an increase in the initial assessment of the porosity factor. It shows that an increase in loading is followed by an increase in the degree of destruction of structural links of natural soils and its nature of compression comes up with the compression of the soils of destructed structure. Structural rigidity of soil can be determined by intersection of lines AC and CD (Fig 1). After the natural structure of clay soils has been destructed, part of its structural rigidity remains. Experimental research shows that there is a short interval AB a small pitch (Fig 2) in a compression curve of limnoglacial kneaded up clay indicating the remaining structural links. According to experimental research, in comparison to natural soils, structural rigidity of the clay soils of destructed structure (kneaded up clay soils) forms a very small part. Therefore when working out engineering tasks connected with construction, we shoned accept that the compression curve of the clay soils of destructed (kneaded up) structure in a semi-logarithmic scale is a line, with its beginning at point A (Fig 2). It indicates that deformation of destructed soils begins with the initial loading (Fig 1, line 3), whereas considerable deformation of natural soils begins under the loading higher than the structural rigidity of the soil.