MATHEMATICAL ANALYSIS OF THE INFLUENCE OF SOIL MASS MOISTURE ON THE DYNAMICS OF CHANGES IN HORIZONTAL LANDSLIDE CREST DISPLACEMENTS

Purpose: to identify the dynamics of changes in horizontal landslide crest displacements with changing soil moisture content in mountainous and foothill areas. Materials and methods. A simulation landslide model was developed using the Midas GTX NX finite element software package. wxMaxima program was used for the mathematical analysis of the obtained dependencies and for identifying slope state change functions. Response functions were obtained for the mathematical model of horizontal displacements Sx (mm), along the landslide crest length L (m), with varying soil moisture content W (%). Results. The analysis of the mathematical model and the response function for the largest constant landslide crest length L (m), F₃(10.64; y) and the lowest massif moisture content W = 10 % allows recording a positive value of horizontal displacement Sx = 0.0157 mm. With a further increase in the soil mass moisture content W, the horizontal displacement Sx will decrease and initially reach a zero value Sx = 0.0 mm at a moisture content W = 11.23 %, and then tend to an extremum along the negative maximum equal to Sx = –0.042 mm, which it will reach at a moisture content W = 19.18 %. A further increase in soil moisture will again ensure a stable approach of the function to zero, Sx = 0.0 mm, which occurs at a moisture content of W = 26.82 %. The displacement will then tend toward positive values and, at the highest moisture content of 36 %, will reach a positive value for this section, equal to Sx = +0.159 mm. Conclusions. According to the conducted research, it was found that when soil moisture content changes from 10 to 18 %, horizontal displacements remain virtually unchanged. However, when soil moisture content changes to 36 %, horizontal displacements increase fourfold, which can lead to the activation of landslide processes.