Showing papers on "Lateral earth pressure published in 1987"

Earth Pressure on Retaining Walls Near Rock Faces

Abstract: The present study examines the lateral earth pressure transferred to a rigid retaining wall by granular fill confined between the wall and an adjacent rock face. The centrifuge modeling technique is used to test small models in which rotation of the wall about its base can be controlled, thus allowing observation of changes in pressure from the at‐rest to the active condition. Janssen's silo pressure equation may be reasonably used for estimation of the atrest pressure, using an earth pressure coefficient, K=1-sinΦ. Significant variations from the estimated pressure may occur next to the wall as a result of small variations in placement conditions. A conservative approach may be to use a decreased Φ value in calculating K. In the active condition, progressive failure in the soil results in a decreased Φ, which should be used when estimating wall pressure. These estimates may be obtained from stress characteristic solutions, or from the silo pressure equation in which a K value compatible with the values o...

Load‐Deformation Response of Axially Loaded Piles

Abstract: A new empirical scheme for simulating the nonlinear point resistance response of single piles in cohesionless soils is proposed. The pile‐soil system is idealized by using a one‐dimensional finite element technique. The shear resistance response along the pile shaft is found by using the concept of t‐z curve proposed by Kraft et al., whereas the new method is used to define the tip resistance response or the so‐called p‐z curve. A generalized Ramberg‐Osgood model is utilized to simulate the nonlinear t‐z and p‐z curves. To check the validity of the method, four examples involving field and laboratory tests on piles in sands are considered. The comparisons between the finite element predictions, and the laboratory and field observations, show good correlation. The results are relevant to a specific class of problems that involve submerged or dry sand, long piles, and a constant value of the lateral earth pressure coefficient.

Theoretical foundation engineering

Abstract: 1. Lateral Earth Pressure. 2. Sheet Pile Walls. 3. Holding Capacity of Anchor Slabs and Helical Anchors. 4. Ultimate Bearing Capacity of Shallow Foundations. 5. Slope Stability. Appendices. Index.

Soil mechanics. 4th edition

Abstract: This book, which is intended to serve the needs of the undergraduate civil engineering student, studies the following aspects of soil mechanics: basic characteristics of soils; seepage; effective stress; shear strength; stresses and displacements; lateral earth pressure, including the design of earth-retaining structures; consolidation theory; bearing capacity; stability of slopes; ground investigation.

Influence of wall yielding on lateral stresses in unreinforced and reinforced fills

Abstract: The relations between boundary yielding and the state of lateral stress in unreinforced and reinforced sand backfills has been investigated at laboratory model scale. The results have shown that lateral expansion of the backfill is necessary to attain the minimum force acting on a retaining structure. The study has also shown that such expansion of a reinforced backfill can reduce the lateral stresses to significantly below that corresponding to the "active" earth pressure condition for an unreinforced fill. Descriptions are also given of methods of achieving controlled yielding of lateral boundaries to attain the minimum stresses acting on a wall and thus avoid problems of unserviceability of the wall or facing units. Although the results were obtained from laboratory models, such information is of considerable significance in relation to the economic design and construction of full-scale retaining structures. (TRRL)

Lateral earth pressure on retaining structure with anchor plates

Abstract: An earth-retaining structure that derives its stability from anchor plates placed in the backfill soil is described. The system has been used for railroad/highway bridge abutments and as earth retaining walls to contain soil. It can easily be installed in stages to reach the desired height, and compares favorably with the conventional retaining wall in construction cost. An analytical solution has been formulated to calculate the system equilibrium state from which the equilibrium lateral pressure can be determined. Based upon the results of a parametric study using granular backfill, it was found that the most significant factor that could affect the lateral earth pressure and the amount of outward wall movement is the ratio of the area of the anchor plates to the area of the wall. The analytical solution provides the basis of a more rational design procedure for the system described.

Retaining Walls With Sloped Base

Abstract: In cantilever retaining walls, sliding often requires widening of the base or development of the key under the base; widening brings additional expenses, while the key is fully efficient only in very firm soil. The alternate solution is the sloped base bottom. The weight of the wall and soil produces normal pressure on the sloped base and a force acting along the bottom surface. Force acting along the surface represents additional resistance to the sliding. It can not be developed to a point greater than the sliding resistance along the horizontal line through the lowest point of the base in the soil under the retaining wall. The sloped base is most effective when the coefficient of friction for concrete cast against soil is relatively low, or when limited excavation is required. However, these conditions are common enough to provide for the sloped base broad application.

Wheel-load-induced earth pressures on box culverts

Abstract: A full-scale 8-ft by 8-ft reinforced-concrete box culvert was constructed and instrumented with earth pressure cells. Dead loads caused by backfill and up to 8 ft of cover were applied in 2-ft increments. Live loads were applied at each level of cover by a test vehicle loaded to represent the alternate interstate design load, consisting of two 24,000-lb axles spaced 4 ft apart. Measured live-load earth pressures on the top slab are compared to various theoretical solutions for concentrated and distributed wheel loads and to pressures predicted by a finite element model. Empirical equations are presented that for shallow covers more accurately model the measured data than do the analytical and numerical methods studied.

Influence of installation method on the behaviour of rigid piles in clay subjected to moment and horizontal load

Abstract: The lateral soil pressure distribution, pile capacity, and displacements of instrumented single rigid bored piles subjected to pure moment and horizontal load have been investigated. The influence of method of pile installation on the above parameters is studied by comparing the behaviour of bored piles with that of jacked piles. It was concluded that the method of installation has practically no effect so far as the net lateral soil pressures and pile capacity are concerned, but the displacements may by up to 3 times larger for a bored pile than for a jacked pile under working loads.

Dilatometer Testing in Highly Overconsolidated Soils

Abstract: The dilatometer was first introduced by Marchetti in 1975. This new in situ device has a very large potential in evaluating some important soil properties. The knowledge of drainage conditions during penetration is an important part of the test results. Unfortunately, the dilatometer by itself cannot measure the pore pressure generated during penetration. Therefore, in order to determine what the drainage conditions were, a piezoblade was designed. This new piezometer has the same shape as a dilatometer. Many dilatometer and piezoblade tests were performed and the dilatometer's first pressure readings were compared to the generated excess pore pressures. From the test results, it appears that the maximum effect of generated excess pore pressure in very overconsolidated soil is about 40% of the dilatometer's first pressure reading.

Wall structure having earth pressure-reducing structure

Abstract: PURPOSE:To greatly reduce the pressure of soil by approaching the action face of soil pressure generated from the slope to a stable slope by a method in which expanded resin blocks are stack in the back-filling layer of a retaining wall in such a way as to make the stack layer of upper layers longer. CONSTITUTION:The back side of natural slope is excavated to form a stable slope 15 in the backward direction. A retaining wall structure 13 is constructed by a back-filling concrete 21, expanded resin blocks 16 stacked, joining blocks 27, and soil 20. In this case, the length of the block layer 17 consisting of the blocks 16 is made longer for the upper stages. The acting face of soil pressures generated from the slope comes near the stable slope, greatly reducing the pressure of the soil.

Passive lateral earth pressure development behind rigid walls

Abstract: An analytical solution procedure is described to estimate the developed passive lateral earth pressures behind a vertical rigid retaining wall rotating about its toe or top into a mass of cohesionless soil. Various stages of wall rotation, from an at-rest state to an initial passive state to a full passive state, are considered in the analysis. A condition of failure defined by a modified Mohr-Coulomb criterion and equilibrium conditions are used to obtain the necessary equations for solution. The development of friction along the wall surface at various stages of wall rotation is also taken into account in the analysis. Finally, the results predicted by the developed method of analysis are compared with those obtained from the experimental model tests on loose and dense sand. The comparisons show good agreements at various stages of wall movement.

Prevention of slide movement of corner retaining wall

Abstract: PURPOSE:To prevent the slide movement of a retaining wall by a method in which a mesh board is connected to a bottom slab in the resultant force of earth pressures, the internal friction angles of back soil is increased, and the earth pressures are reduced. CONSTITUTION:A mesh board 2 consisting of a metal plate, e.g., expand metal, punching metal, etc., plastic chemical fiber net, etc., is connected to the bottom slab 1 of a corner retaining wall in the resultant force direction of earth pressures so that internal friction angles are increased. According to the magnitude of earth pressure, the sizes and number of the boards 2 are optionally regulated. The setting of soil can thus be strengthened by the board 2, the slide movement resistance of the corner retaining wall A can be raised by frictional force acting on the board 2, and the earth pressures can be reduced. Safeness against slide movement can therefore be enhanced.

Construction work of retaining wall

Abstract: PURPOSE:To simplify the execution of a retaining wall as well as to reduce the cost of construction work by a method in which when applying a back-filling work to the retaining wall, a filler having a specific gravity smaller than the surrounding soil is packed into the upside region of the slide face of the back- filling soil to relieve the soil pressure acting on then retaining wall. CONSTITUTION:A filler having a specific gravity smaller than that of the surrounding soil, e.g., concrete mixed with a superlight-weight material such as expanded styrol, air concrete, enclosed pressure can, compressed fiber, etc., instead of the soil of a wedged portion 2, is packed into the upside region of the slide faces (a) and (b) of back-filling soil to be packed into the back side of a retaining wall 1. In the case of expanded styrol, since its density is much smaller than that of soil, or the weight per unit volume is about 1/30 or less of soil, the reaction force of the retaining wall 1 to the earth pressure can be reduced. By using an easily processable expanded styrol, a construction work can be simplified without the needs for large-scale civil construction machines or many labors.

Earthquake Induced Forces on Retaining Walls

Abstract: SUMMARY In this paper, the authors examine the dynamic earth pressure behind gravity retaining walls. The finite element method was used in modeling a gravity wall retaining a dry-cohesionless backfill. The recorded earth pressure behind full-scale walls during earthquakes, as well as the results of several laboratory tests conducted on small-scale wall models, were used to verify the results of the finite element analysis. The study showed that the magnitude of the earth pressure depends on the frequency and maximum peak acceleration of the earthquake. The study indicated also that the dynamic earth pressure distribution is nonlinear and depends on the mode of displacement in the wall

Lateral response and earth pressure parameters of cohesionless soils related to flat dilatometer data: a laboratory study

Abstract: In situ evaluation of soil parameters in the lateral direction such as the at-rest lateral earth pressure coefficient, lateral subgrade coefficient, and lateral soil modulus is required for a variety of soil-structure interaction analyses. A practical device to estimate these parameters is the flat dilatometer. The flat dilatometer requires, however, as do most other in situ penetrometer-type devices, calibration under simulated in situ conditions for possible extrapolation of the results to undisturbed soil conditions. A series of laboratory experiments was conducted to investigate the effects of dilatometer penetration on the soil parameters estimated from the dilatometer data in sands. With regard to the at-rest lateral earth pressure coefficient, the results indicated that the relation between the in situ earth pressure and the lateral earth pressure measured after dilatometer penetration is a function of particle shape characteristics as well as relative density and vertical overburden pressure. The lateral subgrade coefficient and the lateral soil modulus were found to be reasonably linear functions of the corresponding soil parameters determined from the dilatometer data, namely the dilatometer subgrade reaction coefficient and the dilatometer modulus. The range of uncertainty, however, was found to increase with the angularity of the particles in soil. Both particle shape and relative density become controlling factors for the slope and linearity of these relationships in soils composed of angular particles.

Soil pressure-sender

Abstract: PURPOSE:To enhance the efficiency of sending soil under pressure by a method in which an outside cylinder is advanced ahead of a piston before soil stored in a tank is sent out under pressure, a sending pipe is separated from the soil tank, and the piston is advanced to push out soil in the cylinder CONSTITUTION:A casing 1, an outside cylinder 2 for a separator between a soil tank 106 and a pressure-sending pipe 107, a piston 3, a stopper 4 for the piston 3, an inside cylinder 5, a piston 6 for pushing the cylinder 5, a stopper 7, and a piston 8 for sending soil are provided Before soil is stored in the tank 106 and sent out under pressure, the cylinder 2 is advanced ahead of the piston 8, the pipe 107 is separated from the tank 106, and the piston 8 is advanced to push out soil in the cylinder 2 to the pipe 107 The backward pressing of the cylinder 2 when soil is sent under pressure can thus be prevented

Seismic response of tieback rataining walls - phase i. final report

Abstract: The current design practice used by WSDOT for the design of permanent tieback walls is to assume that the static design of a tieback wall retaining clayey soils provides an adequate reserve of strength to prevent failure during seismic loading. This design procedure is based largely on the assumption that the soil and the wall move together during ground shaking and that significant dynamic loads are not produced. For tieback walls retaining sandy soils, it is assumed that dynamic loads are produced. Mononobe-Okabe dynamic soil pressures are added to the static design pressure to account for the dynamic load. The validity of these assumptions and the resultant design practices is evaluated in this study. A pilot numerical study was conducted on a forty foot high wall with three levels of tiebacks using the program FLUSH. It was found that the wall and the soil tend to move in-phase and only negligible dynamic tie forces are generated. However, the soil above and below the excavation level tends to move out-of-phase, leading to significant dynamic pressures and bending moments in the wall and near the excavation level. It appears that in some cases, tieback walls with an adequate static safety factor may suffer significant damage or fail during seismic loading and that the use of Mononobe-Okabe dynamic prssures may be conservative.

Block for vegetative retaining wall

Abstract: PURPOSE:To keep a balance with the soil pressure on the back side of a retaining wall by a method in which a side wall inclined backwards on the upper end of front side and vertically lapped continuous when stacking up blocks is integrally provided and soil is held over the rear portion of the side wall. CONSTITUTION:Blocks 5 for vegetative retaining wall are set in rows at an alternate interval on the foundation and soil 7 is packed into the spaces 6 to form the lower stage. Mutually facing side walls 2 for the adjacent blocks 5 for vegetative retaining wall are set staggeringly and soil 7 is packed into the spaces 6 to form the second stage. The surface of the soil is consolidated by tamping, matted soil with turf is fixed to the surface of the soil 7, and the turfy slope is formed staggeringly. The breakage of the retaining wall by more or less curving of the blocks can thus be prevented without the needs for driving a back-filling material, e.g., concrete or cobble stone.

Experiences with shored excavations

Abstract: This paper considers shoring of excavations associated with construction of buildings with particular reference to the selection of the earth pressure coefficient. The empirical criteria, given by R. B. Peck and other participants at the International Conference on Soil Mechanics and Foundation Engineering in Mexico City in 1969, are examined. Several case histories of deep excavations are given where acceptable deformations were experienced using active earth pressure coefficients in shoring design. Where failure occurred, it was attributed to causes unrelated to the selection of earth pressure coefficient. Key words: shoring, earth pressure coefficient, deformations.