Rational soil model in calculations of fills in a two-and three-dimensional formulation

Conclusions

• 1. The use of methods for calculating earth structures or methods for using their state of stress and strain under conditions of the two-and three-dimensional problems based on assigning the average data on deformation properties of the material leads to errors exceeding the requirements imposed on the accuracy of engineering calculations.

• 2. In calculations based on the use of the nonlinear relationships between stresses and strains it is of considerable practical importance to reflect the properties of contraction and dilatancy of the soils and the relation of the mechanical properties to the form of the three-dimensional stress condition. Consequently, the soil model should include data on the mutual effect of the average stress, stress intensity, and form of the three-dimensional stress condition in all possible variants of its further development (for example, reaction of the effect of the stress trajectory and other factors).

• 3. In solving problems of the stability of earth structures and forecasting the formation of cracks it is necessary to consider jointly the state of stress and strain of the structure and equation of limit equilibrium; data on the strength of materials alone is insufficient in solving these problems. The relation of the strength of soils to the form of the three-dimensional stress condition is of great importance in this case.

• 4. Considering the great practical importance of refining the data on the mechanical properties of material in a three-dimensional stress condition in calculation of earth structures, it is important to undertake a further mathematical analysis for the purpose of determining the role of such factors as the effect of the stress trajectory and rotation of the axes of the principal stresses on the mechanical properties of soils.

• 5. The necessary volume of data on the mechanical properties of soils for calculating the structures can be obtained on triaxial compression devices with independently controlled principal stresses, for example, the apparatus designed by the V. V. Kuibyshev Moscow Institute of Civil Engineering. It is necessary to introduce such devices into research practice for the purpose of designing hydraulic engineering earth structures.