Showing papers on "Lateral earth pressure published in 1989"

Discrete numerical model for soil mechanics

Abstract: The Distinct Element Method (DEM), a numerical technique which treats soil as a discrete assemblage of particles, can be useful when local yield, bifurcation behavior or nonlinear soil‐structure interaction occurs. A two‐dimensional disk‐based implementation of the DEM is validated using numerical simulations of standard geotechnical laboratory tests, such as one‐dimensional compression, direct simple shear and triaxial tests. These test results indicate that the two‐dimensional DEM can simulate realistic nonlinear, stress history‐dependent soil behavior appropriately when individual particle rotation is inhibited.Modeling of large‐scale problems is accomplished by constructing a reduced‐scale model, then applying the geotechnical centrifuge scaling relationships in order to reduce the number of particles simulated and to ensure stress‐strain‐strength similitude between the model and prototype. Full‐scale simulations, including bearing capacity and lateral earth pressure tests, indicate that the DEM can a...

Numerical modelling of the trap door problem

Abstract: The trap door problem is a useful model for providing a clearer understanding of the stress distribution around civil engineering structures such as anchor plates and tunnels. The passive mode can be used either to compute the uplift force of anchors or any buried structure which may be idealized as an anchor; the active mode can be used to compute the gravitational flow of a granular material between vertical walls or the soil reaction curve for tunnel design. Both modes of displacement are modelled numerically in this Paper using the finite element method. The results are presented in the form of influence charts, which may be used for both the passive and active modes to provide failure loads for a range of geometries and soil properties, using non-dimensionalized parameters. The use of these equations is compared with results obtained from other sources using both physical and numerical models. Le probleme de la trappe represente un modele utile pour l'obtention d'une comprehension plus claire de la d...

Arch in soil arching

Abstract: It is shown theoretically that the arch describing the minor principal stress in the soil behind a retaining wall can be approximated by a catenary which is very close to circular in the range of interest.

Agricultural Engineering Soil Mechanics

Abstract: 1 Origins and Classification of Soils Origins of soils Classification of soils Soil phases Problems 2 Soil Shear Strength Coulomb's law of friction and cohesion The Mohr circle of stresses at a point The Mohr-Coulomb circle of stresses at failure The method of stress characteristics Total and intergranular (effective) stresses Laboratory methods of soil strength measurement Field strength tests Problems 3 Shallow Foundations Bearing capacity Foundation settlement Pressure distribution under foundations Tower silo foundations Pile foundations Problems 4 Water Flow in Soils Consolidation and settlement rates Water flow in saturated soil Problems 5 Slope Stability Slope stability determination Stability of watercourse banks Erosion of banks Stability of small earthdams Problems 6 Lateral Earth Pressures Active and passive wall pressures Design of retaining walls Passive soil resistance Pressures on bin and silo walls Pressures on buried pipes and conduits Problems 7 Soil Erosion and Protection Water erosion The universal soil loss equation (USLE) Modified universal soil loss equation The soil loss estimator for southern Africa (SLEMSA) Design of soil conservation practices and structures Wind erosion Problems 8 Soil Cutting and Tillage Cutting forces Volume of soil cut Soil loosening Problems 9 Soil Compaction Compaction for earthwork construction Compaction of agricultural soils Problems 10 Geotextiles Use of geotextiles Design of geotextile applications Problems 11 Soil Freezing Frost penetration Frost heave pressures Problems References Appendices 1 Bearing capacity factors for shallow foundations 2 Design requirements of extended silo ring foundations 3 Wall pressure factors in frictional soils 4 Consolidation time factors 5 Passive soil cutting factors 6 Selected values of soil mechanical properties Author Index Subject Index

Pipe-soil interaction model

Abstract: The PIPESTAB Pipe‐Soil Interaction Project developed a model that predicts the soil resistance to lateral motions of untrenched submarine pipelines. The model improves upon the typical coulomb friction estimation by including soil strength information and pipe displacement history in the resistance prediction. An extensive data base containing results from monotonic and cyclic tests of full‐scale pipe sections on five distinct soil conditions forms the foundation for the model. Pipe‐soil resistance is far more complex than simple friction. Test data convincingly shows a marked dependence of lateral resistance on pipe penetration and soil strength. The improved empirical model captures this dependence by estimating the lateral resistance using two terms, a sliding resistance component plus a soil passive resistance component. The empirical model incorporates all significant trends observed in the test results and is suitable for use in pipeline dynamic response predictions. The testing program significantl...

Calibration of dilatometer correlations

Abstract: The results of the dilatometer test combined with empirical correlations are used to estimate unit weight, coefficient of lateral earth pressure, overconsolidation ratio, constrained modulus, undrained shear strength for clays, and effective friction angle for sands. Recent work also suggests obtaining relative density, Young's modulus, liquefaction potential for sands, limit skin friction for piles in clay and constrained modulus for settlement analysis in sand. The paper evaluates the dilatometer correlations for clays and sands in light of the results obtained in a four-year research program at the Norwegian Geotechnical Institute. The dilatometer is one of the only methods to provide estimates of unit weight, coefficient of lateral earth pressure and overconsolidation ratio simultaneously and very cost-effectively. Important uncertainties still exist, but the evaluation of well-documented sites and the use of consistent reference parameters should reduce the scatter observed in the data underlying the interpretation charts. The correlations are fairly well documented for clay deposits, but need considerable validation for silt and sand deposits.

Soil pressure on box culverts

Abstract: Study critically examines the provisions of the American Association of State Highway and Transportation Officials' (AASHTO) "Standard Specifications for Highway Bridges," relative to design of reinforced concrete box culverts. This paper deals specifically with two topics: soil pressure analysis was performed by finite element modeling taking into account soil-structure interaction. The analysis confirms previous field observations that the AASHTO provisions considerably underestimate soil loading. Formulas are proposed for prediction of more realistic soil pressures. Influence of the proposed soil pressures on culvert size and reinforcement is demonstrated by numerical examples. Both the working stress design and the strength design methods are employed. It is shown that, even with the increase in soil pressures as suggestsed, use of the more rational strength design method could result in material savings.

Effects of geotextiles on lateral pressure and deformation in highway embankments. final report

Abstract: A laboratory study was conducted to evaluate the behavior of a single lift of a geotextile reinforced fill with both a voided and nonvoided face. The testing indicated that only a small deformation (less than 1 in.) is required to produce a 90% reduction in lateral stress. Secondly, a free standing geotextile face develops a configuration which remains stable through repeated loadings. Additional testing indicated that the cardboard is able to sustain construction loads and would deform on wetting. Based on these findings, construction started on the Ozone Bridge, located on Interstate 80 approximately 30 miles east of Cheyenne, Wyoming. Three geotextile reinforced embankments having different abutment face treatments were built while a fourth embankment was left without reinforcement. In one embankment, the geotextile was placed against the wall. In another, two in. of corrugated cardboard were first placed against the wall and then the geotextile was wrapped against the cardboard. After the embankment fill was completed, the cardboard was saturated and collapsed, creaating the void. In the third embankment, plywood forms provided an initial six in. void that closed when the forms were removed. The embankments were instrumented with settlement and inclinometer tubes and two walls had vertical and horizontal pressure cells. Measurements have been taken periodically while the bridge has been in service. The major findings of the study were: 1) The embankment constructed with the cardboard forms showed lower lateral earth pressures (near zero) than the embankment constructed with the geotextile directly against the abutment; 2) The lateral fill pressures were the greatest at the corbel and were lower at depth; 3) Larger movements were measured along the side of the embankment than at the abutment face; 4) The unreinforced embankment had significantly more movement than the reinforced embankments, either with or without the void space; and 5) Differential settlements under all the slabs indicate the need for heavily reinforced concrete approach slabs.

Long-term behavior of flexible large-span culverts

Abstract: Two large-span flexible steel culverts in Norway were instrumented for monitoring long-term behavior. The first structure was a pipe arch with a span of 7.81 m completed in 1982, and the second was a horizontal ellipse with a span of 10.78 m completed in 1985. Both structures are backfilled with high-quality, well-graded dense gravel and sand. The main influence on the long-term effects is likely to be environmental factors such as seasonal temperature and moisture variations. In Norway, the winter is very cold and seasonal temperature changes are great. Hydraulic earth pressure cells of the Glotzl-type are used on both structures, and thermistors are used to measure temperature variations. In addition, strain gauges are mounted on the horizontal ellipse to measure stress changes in the steel structure on a long-term basis. The long-term observation of the flexible steel culverts in this study shows that they undergo changes in earth pressure distribution and structural response as time progresses after construction. On both structures, the horizontal earth pressure at the springline has increased to values somewhat above the overburden pressure. The measured thrust force in the steel on the horizontal ellipse increases considerably with time. Although the measured vertical earth pressure over the top of the structure is less than the overburden, the measured thrust stress indicates negative arching for the structure as a whole.

Laboratory evaluation of lateral swelling pressure

Abstract: A laboratory technique for the determination of the lateral swelling pressure of expansive clays is described. The method uses a hydraulic triaxial cell fitted with a lateral strain belt, and is based on the “Method of Equilibrium Void Ratios” (Sridharan et al). Comparative tests on a high-plasticity clay from southeast Queensland, Australia, using a conventional oedometer cell indicate that the lateral swelling pressure may be more than twice the vertical value. The method has the advantage that a constant vertical stress similar to field conditions may be imposed on the soil sample. Furthermore, lateral strains are measured directly, thus obviating the need for inferring them from measurements of axial and volumetric strain. The method enables the lateral swelling pressure under conditions of some known, finite value of lateral strain to be estimated, which is useful for applications such as retaining walls where finite deflections are inevitable. A disadvantage of the method is the time required to conduct sufficient tests to accurately define the swelling pressure.

Long-term performance of an embedded cantilever retaining wall in stiff clay

Abstract: For embedded retaining walls in clay the critical design condition normally occurs in the long term when pore-water equilibrium has been achieved under the new stress regime near to the wall. This Paper presents the results of a field study of the long-term behaviour of a cantilever diaphragm wall in London clay constructed on the A329(M) near Reading, Berkshire. Lateral stresses acting on the wall were determined from push-in spade cells, from in situ tests using the Camkometer and the Marchetti dilatometer, and from laboratory measurements of soil capillary pressure. The measured stresses are compared with the limiting pressures obtained from assessments of wall stability based on measured strength properties and groundwater conditions. The factors of safety determined from these analyses are then compared with the design values currently recommended. The field data are also compared with finite element predictions of long term behaviour. Pour des murs de soutenement encastres dans de I'argile la condit...

Use of the finite element method in modelling a static earth pressure problem

Abstract: Results obtained with the finite element method are greatly affected by the overall dimensions of the mesh and the number and size of the elements used. Proper choice of the boundary conditions is also necessary to obtain an accurate estimate of the unknowns of the problem. This paper discusses some factors that influence the results of a finite element idealization of the problem of earth pressure behind a gravity wall with a dry, cohesionless backfill. (Author/TRRL)

Modelling of Displacement Piles in Sand Using a Pressure Chamber

Abstract: This paper describes a method of modelling the driving and loading of piles in the laboratory that permits variations of significant parameters and maintains effective stresses at levels that simulate in-situ conditions. A specific example is also described, in which the behavior of a displacement pile was studied under varying conditions of relative density and in-situ stress in a poorly graded, clean, submerged, fine siliceous sand. The laboratory testing system consists of a pressure chamber termed the 'long, variable lateral pressure soil column' (LVLPSC), soil deposition equipment, instrumented model pile, impact hammer, portable loading-test equipment, and digital and analog data acquisition systems.

Analytical study of laterally loaded cast-in-drilled-hole piles

Abstract: This paper summarizes the results of an analytical study of laterally loaded cast-in-drilled-hole (CIDH) piles, which are typically used as the foundations for signposts and sound barrier walls along urban freeways. The CIDH pile derives its bearing capacity from passive earth resistance and is typically considered to be rigid in design and analysis. The analytical formulation, which calculates the ultimate lateral resistance and the point of rotation, considers (a) the nonplane strain soil wedge and (b) the concept of developed friction angle and cohesion to describe the transition of passive lateral earth pressure development from the initial to the ultimate lateral loading condition. Finally, the developed formulation was used to compare the results with those obtained from field and laboratory model testing. Included are comparisons of the ultimate lateral load, the point of rotation, and the distribution of the passive lateral earth pressure.

Engineering correlations for soil deposits in taipei

Abstract: This study aims at establishing empirical correlations for the soil deposits in Taipei City. These correlations are valuable in the planning and preliminary design stages. For cohesive soils, correlations between (1) virgin compression index and nautral water content, (2) virgin compression index and initial void ratio, (3) coefficient of consolidation and liquid limit, and (4) angle of shearing resistance and plasticity index are proposed. Profiles of overcons‐olidation ratio (OCR) as well as strength ratio are presented. Relationships between the coefficient of earth pressure at rest and the angle of shearing resistance and the plasticity index have also been carefully studied. For cohesionless soils, correlations between (1) permeability and effective particle size, and (2) angle of shearing resistance and standard penetration test (SPT) TV‐value are presented. Due to inherent variations in the Taipei soil deposits, there are practical limitations and the correlations presented in the paper sh...

Earth pressures against an experimental retaining wall backfilled with heavy clay

Abstract: This report describes a pilot scale study of the 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 given in the current specification (Department of Transport 1986). The investigation forms a sequel to studies using backfills of sand and silty clay (carder, pocock and murray 1977, carder, murray and krawczyk 1980) and was carried out in three main stages. During stage 1 the clay was placed in an 'as dug' condition and compacted in layers to a depth of 3 metres. On completion of filling the measured total lateral pressures were considerably in excess of the calculated 'active' and 'at rest' values. Stage 2 was a four week rest period during which significant reductions in lateral pressure were measured on both experimental walls. Sand drains were then installed and the water level maintained constant at the surface of the fill during the 20 month swelling stage (stage 3). The average total lateral pressures on both walls rose rapidly to reach maximum values about six months after the start of swelling and then decreased over the following seven months. On completion of stage 3 the measured lateral pressure over the upper 1-1.5 m on both walls were substantially in excess of the calculated limiting passive values. (Author/TRRL)

Behaviour of a propped embedded retaining wall at Bell Common Tunnel in the longer term

Abstract: This is a report of the extensive instrumentation and monitoring and the behavior of a section of retaining wall and adjoining ground at the 4 m long cut and cover Bell Common Tunnel in Essex. Earth and pore water pressures are reported as well as ground movements and wall and roof behavior. In the 4 years since completion of the construction, there has been little indication of any significant change in earth pressure in the London Clay behind the wall while in front of the wall earth pressures have reduced by only a small amount. Comments are also made on the heave of the ground, translatory movement of the wall, and the bending moments and deflexions towards the top of the wall.

Earth pressure behind a gravity retaining wall

Abstract: This paper presents the results of an investigation of the static earth pressure behind a gravity wall with dry cohesionless backfill. A comparison is made between the results of finite element analyses and those of several experimental studies on wall models. The results of the investigation indicate that current design methods do not account adequately for some parameters that may influence the magnitude and distribution of the earth pressure. The study shows also that the design of earth-retaining structures should be based on the amount of displacement permitted in the structure.

Method for constructing architectural big space in great depth underground

Abstract: PURPOSE: To create an architectural space in the great depth underground or an existing building by excavating a shaft of great depth, and constructing large and small diameter shield tunnels and a continuous underground wall to form an underground soil, and then excavating the underground soil. CONSTITUTION: An underground construction method wherein a shaft 1, large and small diameter shield tunnels 2, 3 and a continuous underground wall 4 are formed and then an underground soil 8 is excavated to complete a building space 6. The shaft 1 is used as an advance base for workers and materials and is excavated on the four corners of the continuous underground wall 4. The large diameter shield tunnel 2 is more than 5m in diameter. The small diameter shield tunnel is from about 1 to 2m in diameter and is provided in a position deeper than the ground of an existing building. An artificial ground 8 is formed as a horizontal water stop wall of more than 30m to support earth pressure and ground water pressure. The continuous underground wall 4 is so constructed to support sideward earth pressure and ground-water pressure, and sediment etc., is excavated to complete the space 6. COPYRIGHT: (C)1991,JPO&Japio

Landslide protection wall method

Abstract: PURPOSE:To reduce the cost of execution by improving the ground by performing the driving of the quick lime piles along by the side of an excavated wall of a retaining wall in the poor subsoil and chemical grouting, and generating no concentrated stress locally on the retaining wall. CONSTITUTION:The quick lime piles 11, 11... with a specific depth are driven to the side of an excavated wall 10f of a retaining wall 10 in the ground G along by the retaining wall with a certain interval. And, when the quick lime piles expands in the ground G, pressure F is added transform the excavated wall so as to the retaining wall 10 into the back side, and, at the same time, to provide bending moment and an inverted moment caused by the back earth pressure when excavation are provided. According to the constitution, the deformation amount of the retaining wall can be reduced.

Earth pressure means shield excavating additives and earth pressure means shield construction

Abstract: PURPOSE:To enable sandy ground to be also efficiently excavated and reduce a coat, by using the additives of thickener and water mixed with each other having the main component of fly ash, for earth pressure means shield excavation. CONSTITUTION:According to the excavation of a shield machine 1, excavated earth is taken in a chamber 6 set on the rear side of a cutter, and a screw conveyor 9 set in the chamber 6 is rotated to discharge the excavated earth. In this case, into the excavated earth taken in the chamber 6, the additives of thickener and water mixed with each other having the main component of fly ash is injected from an additives injecting pipe 7, to be added and they are mixed with each other in the chamber 6, and mixed earth is produced. Besides, the rotation of the screw conveyor 9 is interlocked with the excavation of the shield machine 1, and earth pressure in the chamber 6 is balanced with the earth pressure of a facing 3, and natural ground 2 is prevented from being destroyed.

Seismic Response Considerations in Foundation Design

Abstract: There are no generally accepted procedures to determine the potential magnitude of reduction of footing bearing capacity that may result from soil strains or pore pressure changes during an earthquake, except for the limiting case of soil liquefaction. Analyses summarized in this paper indicate that, at present, seismic effects on bearing capacity can only be approximated within broad ranges. The significant conclusion is that the most prudent present approach to seismic design of spread footings is the use of conservative static foundation design parameters.

Steel tubular pile and sheathing wall therewith

Abstract: PURPOSE:To permit the bending strength in a specific direction and an earth pressure-receiving face to be freely set up by a method in which steel tubular piles of an oblong cross section are driven adjacently to construct a sheathing wall. CONSTITUTION:Steel tubular piles 1 of an oblong cross section are driven adja cently to construct a sheathing wall 6. In case where the short pieces S of the piles 1 are set in the earth pressure direction to construct a sheathing wall 4, the bending strength per pile is decreased but the earth pressure-receiving area is increased, raising the economical advantage of the construction. Also, in case where the long pieces L of the piles 1 are set in the earth pressure direction P to construct a sheathing wall 5, the bending strength against the pressure P is increased. By constructing a sheathing wall 6 by connecting the long pieces L inclined by an angle (alpha) to the earth pressure-receiving face, a proper combination of bending strength and earth pressure-receiving area can be set up.