Effect of displacements of a retaining wall on parameters of the lateral earth pressure diagram

Abstract

Actual observations of earth pressure on retaining walls and laboratory experiments in fl,-,es show that the pressure and its redistribution over the height depend on kinematic displacements caused by external forces and deformation of flexible retaining walls. Consideration of these factors in a theoretical determination of earth pressure on retaining walls is complicated by the fact that depending on its working conditions the backfill is in a state of inhomogeneous stress and it8 physical and mechanical properties are characterized by nonlinear dependences. In connection with this a number of suggestions have appeared in which the properties of soil to change the pressure on retainlng walls during their yielding and deformation are taken into account. The suggestions of G. K. Klein, N. K. Snitko, A. Ya. Budln, G. Ao Dubrov, A. K. Bugrov, V. F. Rayuk, I. K. Semarln, and others are most known. The indlcatedmethods are of practical interest and permSt more reliable calculations, but they are not sufficiently universal. Therefore the development of universal methods of detemlnlng earth pressure on retaining walls is quite important.Engineering methods of the deformation theory of small elastoplastlc deformations [1] can serve as the basis of creating such methods for a wide range of backfill soils. In combination with the flnite-element method (FEM) these methods permit Investlgating the behavior of a retaining structure comprehensively at various stages of construction and operation. In this case the scheme of "instantaneous" construction of the structure, which should be calculated by the method of variable parameters of elasticity (MVP), corresponds to the operating period. The use of the successive loadlngmethod (SLM) permits modeling the conditions of layer-by-layer construction of the structure.The choice of the FEM as the numerical tool for solving the stated problem is explained by its broad possibilities for taking into account the shape of the structure, loads actlng on it, real properties of soils (inhomogeneity, anlsotropy, nonlinearity, etc.), character of constructing the structure, kinematic conditions of its work, and a nmnber of other factors.In the present work calculation of the "structure-soil" system is replaced by an investigation of the interaction of a linearly elastic rough retaining wall contacting a physically nonllnearly deformable (elastoplastic) sol1 medlmn through a l~yer of special one-dlmensional contact elements corresponding to P. L. Pasternak's two-paremeter model of a foundation and simulatlng friction between the wall and backfill [2,3].Taking into account that the solution is obtained on a B~SM-4 computer with the use of magnetic droms, we regard the "structure-soil" system as a set of individual substructures: wall--hypothetlcal foundation-calculated backfill region.Two types of the problem being solved are possible: "instantaneous" or "layerwlse" construction of the wall and backfill. In the calculation scheme the backfill region having height H and length L = 4H is appro...