Wytrzymałość gruntów na ścinanie w warunkach wysokich ciśnień

Abstract

SHEAR STRENGTH OF SOILS UNDER HIGH PRESSURE CONDITIONS Summary The paper presents results of laboratory tests of shear strength of soils under pressure changing from 0 to 200 kG/cm2. The studies were carried out on samples of soils from the blanket of open-cast brown coal mine from Bełchatów and sulphur mine from Machów. They were carried out with the use of a special apparatus to triaxial compression with a possibility of measuring pore pressure during shearing and outflow of water consolidation. Two schemes of tests were chosen: with and without consolidation and with constant lateral pressure and increasing vertical stress. The results obtained have shown that the soils studied are characterized by curved strength envelope in the range of pressures applied. A change in inclination of envelope takes place under pressure specific for each soil. The effect is the lowest in the case of soils characterized by differentiated granulometry and the greatest in the case of overconsolidated clays. This gives further support to the statement that the value of the parameter B in not constant but rather markedly depends on the range of pressures applied, exceeding those acting at present and in the past. Moreover, there was found a marked dependence of the ratio of principal stresses and shearing angle of a sample on the pressures applied.