Showing papers on "Lateral earth pressure published in 1979"

Seismic Behavior of Gravity Retaining Walls

Abstract: First, the paper shows that in order to use the quasi-static Mononobe-Okabe analysis for the prediction of earthquake dynamic forces on a gravity retaining wall, wall inertia effects must be included. Second, a design procedure is developed in which the designer chooses an acceptable level of wall displacement: he then computes the design wall weight which will restrict displacement in an earthquake to the predetermined level. Wall inertia effects are shown to be of the same order as the dynamic soil thrust, and to be sensitive to vertical acceleration and to base and wall friction. Design recommendations are given which relate to proposed American provisions for seismic zoning.

The effects of compaction on retaining walls

Abstract: It is widely recognized that compaction of fill behind earth retaining structures can induce lateral earth pressures that vary considerably in magnitude and distribution from those predicted using classical earth pressure theory. This Paper presents a simple analytical method which relates induced lateral earth pressures to the effective line loading imposed by compaction plant. Although by no means definitive, the method proposed permits a meaningful assessment of compactioninduced lateral pressures without recourse to complicated mathematical models. Predicted pressures are compared with observed pressures from two case histories, in a third case history the performance of a retaining wall is compared with predictions made using classical theory and the proposed method. A comparison is made between the factors of safety assumed to exist in conventional retaining wall design and those resulting when compaction effects are taken into account. II est couramment admis que le compactage du remblai derriere l...

Zero Extension Line Theory of Earth Pressure

Abstract: A theory of earth pressure for sand is developed. The theory is based on a simplified zero extension line field. Equations and charts for computing earth pressure coefficients with various values of wall roughnesses are presented. The results compare favorably with Sokolovski's coefficients of earth pressure. It is also shown that for active case in dense sand the direction of major compressive stress near the wall is almost vertical even for a very rough wall. A useful coefficient of roughness for the wall is defined. The results are compared with those predicted by Sokolovski, Coulomb, and Rankine theories.

Earthquake-Induced Lateral Soil Pressures on Structures

Abstract: Based on the behavior of backfill soil, the state of knowledge reflects three design approaches: elastic solutions, elasto-plastic solutions and fully plastic (static) solutions. The major differences in the fully plastic solutions utilizing Mononobe-Okabe's approach have been with the application point of the resultant force. Plastic solutions do not consider soil-structure interaction effects and are based on rigid body motions. Elastic dynamic solutions are proposed that provide guidelines to estimate backfill pressures for small lateral displacements. Solutions are also provided to estimate dynamic pore-water pressures. The study of these papers indicates that there is a general lack of a comprehensive treatment of the subject and there is a need for further investigations in the following areas for the dynamic case: passive soil pressures; elasto-plastic backfill soil models; soil-structure interaction effects; mixed soils; surcharge effects; and wall stability for combined bearing, sliding, and overturning.

Model Study of Circular Sheetpile Cells

Abstract: A series of large scale circular sheetpile cell models was constructed, instrumented and tested. Distribution of stresses and deflections of the sheetpiles for various stages of testing are presented. Interlock forces behind arc connections to the main cells were shown to be smaller than the forces in the front sheetpiles. Behavior of model cells during failure under large lateral load is described and a mechanism for cell fill distortion developed. Overturning resistance of cells is compared with values calculated from previous theoretical models. A modified vertical shear mechanism of failure is proposed. Values of coefficient of lateral earth pressure appropriate for calculation of overturning resistance are presented.

Retainining Wall Performance during Backfilling

Abstract: Field data relating to the structural failure of a long reinforced concrete cantilever retaining wall are presented The results of a survey of the defected form of the wall are included Analyses of the wall are carried out using classical earth pressure theories with geotechnical data Using the measured soil parameters, the predicted bending moment at the base of the wall stem was found to be less that 5% of the actual bending moment realized This discrepancy is due to the effects of lateral earth pressures induced by compaction A simple method of analysis is proposed to take into account the effects of compaction Reanalysis of the wall using this method and the measured soil parameters gives a bending moment that is in very close agreement with actual bending moment developed

Yield line analysis of square footings

Abstract: The yield line theory has proved to be quite accurate in determining the strength of reinforced concrete slabs. It has also been found to be more accurate than other methods for analysis of square footings. However, computations by the yield line theory involve some effort. Thus, curves have been included here for determining yield moments in square footings subjected to axial loads assuming soil pressures to be uniform as well as parabolic. These are intended as a design aid. Effect of parabolic soil pressure distribution on footing size and yield moment has also been considered. Design moments can be easily determined on the basis of yield line theory by using moment curves for uniform as well as parabolic soil pressure distributions. It is evident that for n 1 (rigid footing on cohesionless soil) footing area increases and moment reduces. In the latte case these changes are smaller than the former. Also percentage change in moment is much smaller than the change in footing size. (Author)

Reliability analysis of retaining structures

Abstract: The objectives of this study are (a) to examine some of the uncertainties that are involved in the description of the lateral pressures against retaining walls, and (b) to determine the probability of failure of such structures through an application of a system (or, combinatory) reliability analysis. The method of redistribution of pressure (or, dubrova's method) is employed to derive the expression for the pressure distribution along the wall. This depends on three factors; namely the phi parameter of soil strength, the friction angle between the wall and the backfill material and the location of the point around which the wall rotates during failure. To account for the uncertainty in their numerical values, these factors are taken to be random variables instead of uniquely valued quantities. The safety of the retaining wall is measured through its probability of failure rather than the customary factor of safety. Four possible modes of failure are examined: (a) overturning, (b) base sliding, (c) bearing capacity and (d) overall sliding. Assuming that each mode occurs independently of the others, a single value for the probability of failure of the wall is found through a system reliability analysis. Finally, the developed analysis is illustrated in a case study and the obtained results are presented and discussed (a).

Embankment construction resistant to erosion and earth pressure - has layers of vegetation and earth fill incorporated in open structure

Abstract: Beam-like wood or prefabricated concrete spacial framework structures wtih a wall slope of some 5:1 to vertical are assembled and the hollow chambers filled with earth material. This is reinforced with e.g. brushwood layers or hedgerow layers. The brushwood layers extend beyond the leading and rear sides of the spacial framework. Successive layers of brushwood and earth material are incorporated. The former are built up at a vertical separation of 20 to 50cm. The layers comprise living plants or plant segments and have preferably a length of some 1.5 to 2.0m.

Soil restraint against horizontal motion of pipes. closure

Abstract: In this response to points raised by discussers, the author agrees that, for a pipeline placed in a ditch, placement and compaction of backfill material will control the early behavior of the pipe while ultimate lateral resistance is likely to depend mostly on in-situ soil characteristics. This should be taken into account to develop "hybrid" p-y curves. The author also concurs with the discusser on the need to provide the structural engineer with a range of soil restraint characteristics instead of a unique p-y curve. It is also pointed out that while it is recognized that the finite element method is quite versatile and able to easily accommodate for various boundary conditions, it is believed that the finite element method is more adapted to detailed analysis of short lengths of pipe rather than long sections due to the prohibitive costs if an adequate characterization was to be sought. It is believed that computer programs such as NEWPIPE or PIPLIN which make use of elastoplastic discrete springs, are more suitable to handle large pipeline configurations and can provide accurate analyses at a reasonable cost. Further comments are made on the possible end effects in the experiments, and on soil-pipeline interaction and for associated relationships.

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

Abstract: 1. The application of the FEM to calculation of lateral earth pressure on retaining walls offers broad opportunities for numerical modeling of their behavior at various stages of construction and operation, since the results of the calculations agree sufficiently closely with the experimental data. 2. The use of a third-generation computer will permit calculating various structures with consideration of the diversity of acting factors, which will help to provide economic and high-quality designing of these structures.