The design of stiff in situ walls retaining overconsolidated clay part 1: short term behaviour

This paper contains the summary of a previously published paper and for the abstract see IRRD 827411. It also contains clearer diagrams, a worked example which illustrates the new method of calculation, and the references and the conclusions as there was insufficient space to include these in the previous edition of the paper. The conclusions given are as follows:- (1) mobilised soil strengths depend only on the assumed shape of the lateral pressure diagram; (2) the calculation of mobilised strength in the temporary works condition can depend significantly on the possibility that water can enter tension cracks; (3) the influence of differences in shear strain between different soil zones can be explained; and (4) the undrained deflection of in-situ walls, either unpropped or propped near the top, can be estimated by assuming them to be rigid. Both parts 1 and 2 of the paper have also been published as a Transport and Road Research Laboratory Contractor Report CR 199 (see IRRD 830155)

The design of stiff in situ walls retaining overconsolidated clay. Part 1: Short term behaviour. Part 2: Long term behaviour

In urban areas of the United Kingdom increased use is being made of embedded retaining walls both for new road construction and road improvements. Many of the urban areas in the UK are founded on deposits of stiff, overconsolidated clays of high plasticity which present difficulties for the design of geotechnical structures. A programme of research into the behaviour of embedded walls in stiff clay is being carried out by the Transport and Road Research Laboratory, aimed at improved methods of design. A method is set out by which designers can check both the safety and serviceability of relatively stiff reinforced concrete retaining walls constructed in-situ in overconsolidated clay. The first calculation is of the mean soil strength which must be mobilised for equilibrium. Shear stress-strain data are then used to deduce the characteristic shear strain. This is then distributed between the various soil zones, according to geometrical rules, and an estimate of wall deflection is made. A comparison is given between the pattern of ground movement predicted by this method and that observed in centrifuge model tests. It is also shown that the use of mean mobilised strength leads to larger bending moments in the long term than the method proposed in CIRIA Report 104 (see IRRD 281371). Part one of this report was also published in Ground Engineering 1989 v22 n8 (see IRRD 827411).<br/

The pressure of clay backfill against retaining structures

This paper investigates the pressures exerted by clay backfills against retaining structures. The lateral pressures are developed during three main phases: placement, compaction, and burial; horizontal total stress reduction at constant moisture content; and swelling or consolidation under approximately constant vertical stress. Experimental data from laboratory and pilot-scale studies, using clays of intermediate and high plasticity, are presented and used to assess the magnitude of the pressure changes in each phase. The process of compaction is examined and it is concluded that previously developed theories for assessing the pressures on retaining walls developed by compaction of granular soils are inapplicable for cohesive soils. The factors controlling the swelling of cohesive backfill are reviewed and results from a preliminary numerical study are used to provide an indication of the likely effects of plasticity and placement moisture content

Earth pressures against an experimental retaining wall backfilled with heavy clay

Details a study of compaction and swelling pressures developed by a clay backfill against two experimental retaining walls. The plasticity of the clay was well outside the upper limits for cohesive fill to structures. <br/

A parametric study of the stability of embedded cantilever retaining walls

SIGLEAvailable from British Library Document Supply Centre- DSC:7768.29(TRRL-RR--116) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Discussion. Limit equilibrium design methods for free embedded cantilever walls in granular materials

This Paper is fairly restricted in its subject matter, but, as will be discussed later, there areimplications which are common to most formsof geotechnical design. 49. The subject of the Paper is restricted to a simple wall type (Fig. 1) embedded in granular soil...<br/