Showing papers on "Lateral earth pressure published in 1994"

Passive earth pressures with various wall movements

Abstract: This paper presents experimental data of earth pressure acting against a vertical rigid wall, which moved into a mass of dry sand with a stress‐free horizontal surface under various wall‐movement modes. To investigate the variation of earth pressure induced by the rotation about a point above the top (RTT) and rotation about a point below the wall base (RBT) types of wall movement, the instrumented retaining‐wall facility was developed at National Chiao Tung University. Based on experimental data it is found that, for a wall under translational movement, the passive pressure distribution is linear and in good agreement with Terzaghi's prediction based on the general wedge theory. For a wall under either RTT or RBT mode, the magnitude of passive thrust and its point of application are significantly affected by the mode of wall displacement. However, if the parameter n indicating location of the center of rotation is greater than 2.0, the influence of movementmode on passive earth pressure becomes less impo...

Dynamic modeling and response of soil-wall systems

Abstract: Following a brief review of the inaccuracies that may result from the use of a popular model for evaluating the dynamic soil pressures and associated forces induced by ground shaking in a rigid wall retaining an elastic stratum, the sources of the inaccuracies are identified and a modification is proposed which, while retaining the attractiveness of the original model, defines correctly the action of the system. In the proposed modification, the soil stratum is modeled by a series of elastically supported, semiinfinite horizontal bars with distributed mass rather than by massless springs. The concepts involved are introduced by reference to a fixed-based wall retaining a homogeneous elastic stratum, and are then applied to the analysis of more complex soil-wall systems. Both harmonic and transient excitations are considered, and comprehensive numerical solutions are presented that elucidate the actions of the systems examined, and the effects and relative importance of the numerous parameters involved.

Generalized Coulomb Active‐Earth Pressure for Distanced Surcharge

Abstract: Earth‐pressure problems are of great interest in geotechnical engineering and closed‐form solutions for evaluating the active‐earth pressure are widely used in the design of retaining structures. The note presents a closed‐form solution based on the Coulomb‐failure wedge for the case in which a surcharge is applied a certain distance from the wall. This allows the earth pressure to be evaluated according to the actual‐site conditions and to avoid uneconomical design. The basic assumptions are that the failure surface is a plane; the soil is homogeneous, dry, and cohesionless; and the extent of the surcharge is sufficiently large to ensure that the failure plane intersects it at the ground surface. Indications are then given to ensure the compatibility of the solution with the real‐site conditions.

Seismic lateral pressures in soils with cohesion

Abstract: A full-range, elastic-plastic solution for seismic stresses in the free field is obtained for an ideal Mohr-Coulomb material with cohesion. In addition, the effect of uniform surface tractions are included as are both constant vertical and horizontal acceleration components. Moreover, the basic equations are general in that they include both the active and passive cases where the lateral boundaries deform in a similar fashion but move less or more in magnitude than the free field dictates. Thus, this solution can be used directly to determine the seismic lateral pressures on walls or, for the special case when no wall is needed, the critical seismic height of a vertical cut in a cohesive soil. Conversely, the equations can be used to find the critical acceleration level at which a wall with a given factor of safety will move in an earthquake. Finally, once this critical earthquake intensity level is determined, the actual incremental accumulation of displacement of a given wall can be calculated by the simple sliding-block approach or a wall can be designed to limit the seismic displacement to an acceptable level.

Compaction of an Earthy Sand by Rubber Tracked and Tyred Vehicles

Abstract: Normal stresses exerted by two agricultural vehicles (a rubber tracked Caterpillar Challenger 65 and a Steiger Tiger 550 4WD tractor fitted with low pressure dual wheels) were measured with electronic earth pressure cells at four depths (150, 300, 400 and 500 mm) in a sandy soil located in the West Australian wheatbelt. Cone penetration resistance and dry bulk density were also measured at these depths before and after traffic treatments. Uniaxial soil compression testing was done on soil cores sampled at the 300 mm depth where the peak normal stresses were measured during vehicle passage. The Cat 65 exerted less normal stress on the soil than the Steiger 550 at 400 and 500 mm depth. However, the soil had a higher penetration resistance after the passage of the Cat 65 relative to the Steiger 550. Profiles of cone penetration resistance were more discriminating in distinguishing soil physical changes among the trafficked and untrafficked treatments than dry bulk density and most of the parameters derived from compression tests.

The effect on propped diaphragm walls of rising groundwater in stiff clay

Abstract: The Paper investigates the stability and serviceability of propped diaphragm walls constructed in situ in stiff clay, flrst when an excavation is formed in front, second when the groundwater level recovers, and third when it is raised. Three centrifuge model tests were conducted to observe the behaviour of these structures. Simplified behavioural mechanisms are shown to provide a method of analysis for a propped diaphragm wall which would permit a designer to calculate the soil and structural deformations without recourse to expensive and complicated computer-based analyses. The essential conditions are the satisfaction of equilibrium and compatibility requirements, and the ability to use stress-path specific stress–strain data. Where there was little structural displacement, the earth pressures were calculated using a bilinear approximation to the measured stress path of kaolin in one-dimensional swelling. L'article etudie la stabilite et la capacite de service de murs diaphragmes etayes, construits dans...

Stress-Deformation Behavior of an Embankment on Boston Blue Clay

Abstract: An 11 m high I-95 embankment was thoroughly instrumented with piezometers, settlement rods and inclinometers to measure the behavior of the underlying 40 m thick deposit of Boston Blue Clay (BBC) during staged loading and four years of subsequent consolidation. This paper uses updated estimates of the engineering properties of BBC at the site, based on several major in situ and laboratory test programs, in order to perform finite element analyses that incorporate coupled consolidation with two generalized effective stress soil models, Modified Cam Clay (MCC) and MIT-E3. Comparison of predicted versus measured performance during 1967-1973 led to four principal conclusions: (1) The analyses give reasonable predictions of pore pressures and the overall magnitudes of deformations, except in the upper 15 m of the clay crust where uncertainties in the stress history were evaluated using two preconsolidation pressure profiles. (2) Differences between the two soil models lie primarily in the predicted horizontal displacements, for which MIT-E3 gives better agreement with measured behavior. (3) Measurements of outward horizontal displacements (lateral spreading) after the end of construction are predicted as a consequence of anisotropic yield in the MIT-E3 model and are most probably not related mainly to creep of the clay as postulated by others. (4) During consolidation, the analyses predict a significant reduction of centerline vertical total stress due to arching which contradicts the conventional assumption of constant total stress.

Uplift capacity of small-diameter drilled shafts from in situ tests

Abstract: Predictions of the ultimate uplift capacity of six small-diameter drilled shafts installed in stiff cohesive soil are compared with pullout tests conducted to failure. The shafts were installed by the dry-hole method with gravity free-fall concrete placement, and were 76 mm and 152 mm in diameter with lengths ranging from 1.52 to 4.57 m. Predictions of the ultimate uplift capacity were made assuming that failure takes place as a result of perimeter shear. An effective stress model was used with soil parameters obtained from in situ tests. Soil shear strength was obtained from the results of borehole shear tests, and an interpreted profile of in situ, at-rest horizontal soil stress was obtained from the results of prebored pressuremeter tests. The results of the test program demonstrate that the borehole shear test and pressuremeter test may be used in combination to design drilled shafts for uplift resistance in stiff soils.

Effect of overburden pressure on liquefaction resistance of sand

Abstract: The effect of overburden pressure on liquefaction resistance of sand is studied and results of a site-specific investigation are presented. When estimating liquefaction resistance of sand from the ...

An analysis of pressuremeter holding tests

Abstract: The self-boring pressuremeter-Camkometer- was used to define the permeability characteristics of Fucino clay using strain-holding and stress-holding tests. The probe was expanded to a specific value of cavity strain; then the strain or stress was held constant while the dissipation of the excess pore pressure, induced by the initial expansion of the probe, was monitored. The decrease of pore pressure obtained with time was used to derive the coefficient of consolidation for horizontal flow ch. To account for the two-dimensional nature of the problem and the non-linear soil behaviour, numerical analyses were performed which simulated the tests by using the finite element program CRISP, which employs a coupled consolidation theory and the modified Cam clay soil model. The numerical simulation was used to investigate the dependence of the maximum excess pore pressure on the stress history and on the strain level, the necessity to account properly for the soil non-linearity in order to follow the decrease of ...

Behaviour of saturated expansive soil and control methods : under the auspices of Central Board of Irrigation and Power

Abstract: Part 1 Properties: Conventional and in situ properties Swelling pressure and heave. Part 2 Shear strength: Studies Studies with CNS surcharge. Part 3 Earth pressure behaviour: Literature on lateral pressure theory on conventional soil system Investigation on MRBC 76 soil for K0 condition Studies on MRBC 37 soil system for K0 condition with additional instrumentation Laterial pressure development under Ka condition Development of mathematical relations based on cohesion concept Lateral pressure under Kp conditions. Part 4 Load bearing aspects: With and without CNS and MSM. Part 5 Soil improvement. Part 6 Mechanics: Guidelines for lining of canals in expansive soil. Patr 7 Case histories.

Application of the observational method to a deep basement excavated using the top-down method

Abstract: In excavation works, there are limitations in the ability to model earth retaining structures and select soil parameters for design. This is because of the variable and complicated retaining wall structure conditions. The soil and structure behaviour are often monitored to confirm the safety of excavation works during construction. The data are rarely used to improve predictions and modify the design of subsequent stages of construction. The back-analysis of excavations made after construction is very useful in the evaluation of the assumptions and parameters which influence the behaviour (Lambe, 1973). However, it may be advantageous to use the measured data to rationalize the design at the later stages of construction. This is an extension of the observational method described by Peck (1969). In this Paper, the observational construction method is proposed whereby the excavation sequence is modified and optimized during construction. An example of its application is given. The method can be used to revi...

Generalized coulomb active-earth pressure for distanced surcharge. technical note

Abstract: In this note, the author reviews the advantages of the Coulomb method for determining active-earth pressure for distanced surcharge. The note reveals that various closed-form solutions are applied in geotechnical engineering problems; however, most earth-pressure-active coefficients are derived from soil weight alone and do not take surcharge applied on the ground profile into account. The Coulomb approach is based on the limit-equilibrium method and is reliable for the case of the active state. Also, the Coulomb method allows solving earth- pressure problems with various boundary conditions, which for the purpose of this note, is more appropriate. Two examples of earth-pressure problems are presented. The analytical solution is compared to the Coulomb graphical approach, assuming various slopes, surcharge, and earthquake loadings. The author concludes that a closed-form solution is strictly dependent on boundary conditions, that is, one must verify the compatibility of the solution with the boundary conditions of each problem.

Static and dynamic measurements using embedded earth pressure cells

Abstract: As part of a research program to study lateral earth pressures on retaining walls, dynamic compactor forces were measured by two methods: (a) a direct instrumentation method that is thought to yield reliable measurements of dynamic compactor forces and (b) taking measurements of embedded earth pressure cell responses that are converted to estimated compactor forces at the ground surface. Comparison of the compactor forces from the two methods disclosed the following: (a) Reflection of seismic waves from the boundaries of the backfill can create a standing wave at the embedded pressure cell location, which may cause pressure cells to overregister. (b) The pressure distribution beneath the base of the compactor can influence the embedded pressure cell readings. (c) Use of a registration ratio of unity resulted in estimated compactor forces that were generally in as good, or better, agreement with the forces measured by the direct instrumentation as when in situ registration ratios were used. During the in situ calibration studies, several factors that can influence the response of embedded pressure cells to static loads were identified: the presence of clods in the backfill can influence pressure cell response, even when the diaphragm size to soil particle size criterion is well satisfied; compaction-induced lateral earth pressures can cause nonlinearity in pressure cell response because of the rotation of lateral stresses; and other factors, such as variations in cell placement conditions, can influence pressure cell results.

Fundamental study on static deformation behavior of tunnel lining

Abstract: 変状対策や近接施工におけるトンネル覆工の力学的な健全度評価法を確立することを目的として, 覆工模型実験及び骨組解析によるシミュレーションを行った. 地盤と覆工の相互作用が表現でき, 3次元実験が簡易に行える実験装置を開発し, これにより種々の比較実験を行った. 本論文では, 各種のパラメータがトンネル覆工の変形挙動に与える影響について述べる.

Shoring and cut-off method by underground continuous wall

Abstract: PURPOSE:To execute construction efficiently and to reduce a construction cost by constructing a continuous wall ensuring cut-off efficiency first of all until it reaches a water impermeable in a deep part, and constructing continuous walls playing a reinforcing part against earth pressure in piles up to a required depth from the upper end. CONSTITUTION:A continuous wall 1 of reinforced concrete is constructed unit it reaches a water impermeable layer 4 in a deep part in the ground, and cut-off efficiency is ensured. After than, reinforced walls 2 and 3 constructed to the inside or the outside of the continuous wall 1 up to a required depth from the upper end in piles and are made to resist external pressure. If necessary, the continuous wall 2 is construction of materials having heat insulation efficiency. According to the constitution, construction is efficientry executed and, at the same time a construction cost be reduced.

On the enhanced confining pressure aproach to the mechanics of reinforced soil

Abstract: A review is presented of conceptual approaches that are currently in use for interpreting the operation of reinforced soil. The concepts of enhanced confining pressure and of reduced normal tensile strains are found to be closely related to current experimental and theoretical investigations as well as to the design methodologies available at present for reinforced soil applications. Focusing on the enhanced confining pressure concept, analytical expressions are developed that allow the estimation of the value of equivalent confining stress increase when the properties of soil and reinforcement and the state of stresses acting on a cylindrical reinforced soil element are known. The derived expressions can also be utilized for estimating the soil-reinforcement friction angle from the results of triaxial tests on cylindrical samples reinforced with horizontal layers of reinforcement.

Foundation Uniform Pressure and Soil‐Structure Interaction

Abstract: Practicing foundation engineers tend to consider the foundation load as the point load when they want to consider its influence on the adjacent foundations. They believe that it will yield conservative results when a Boussinesq equation is considered. This derivation shows that such an assumption is groundless. The effect of uniform pressure on the adjacent foundations could be as high as 25% more than its effect when the pressure is lumped as a concentrated load at the center of the footing. The derivation converts the square footing into a shape that fits the polar coordinates. Such conversion facilitates the integration of the uniform pressure effect of one footing on the adjacent footings. Parameters and limits of integration are derived, then used in a practical example.

Dynamic Lateral Pressures Due to Saturated Backfills on Rigid Walls

Abstract: One-directional (horizontal) shaking-table experiments were conducted on one sandy and two cohesive saturated backfills to investigate the dynamic water and total lateral pressures against rigid nonyielding walls during earthquakes. It was found that the dynamic water pressure against the wall is generated due to two different sources. The first source is Westergaard-type, which is due to the flow of free water in nondeformable backfill soil skeleton and the second is due to the deformability of backfill soil skeleton under undrained conditions. For highly permeable backfill soils, the first source dominates in the generation of pore pressure and the second source dominates for cohesive backfills. The magnitude of the first type of dynamic water pressure is expressed as a function of the parameter 2π\inγ\i\dw\iH²\iw/\iE\dw\ik\iT, where \in is the porosity of soil, γ\i\dw is the unit weight of water, \iH\i\dw is the depth of water table to the impermeable base in the backfill, \iE\i\dw is the coefficient of compressibility of water, \ik is the coefficient of permeability of pressure distribution is a shape of the Westergaard solution. The distribution of the second type is different from the Westergaard-type with a peak value at an upper section of the backfill depth and zero at the bottom. The dynamic water pressure resultants of this type for cohesive backfills are nearly as much as the value of the Westergaard’s but is applied at approximately 0.6 \iH from the bottom of the backfill. The dynamic total pressure resultants for cohesive backfills are nearly twice Westergaard’s dynamic water pressure resultant and also applied 0.6 \iH from the bottom of the backfill.

Earth retaining wall in soft ground and earth retaining construction method

Abstract: PURPOSE:To improve executing ability by forming a wall body of plurality of column bodies composed of columns made of excavated soil and filler which are uniformly mixed each other, and mutually overlapping the outer peripheries of the columns for unifying them. CONSTITUTION:A earth retaining wall 1 being square in a plane is executed to a ground abutting on the periphery of a building. The wall 1 is formed of a column body made by arranging columns 2 composed of excavated soil and filler such as cement system solidifying agent, which are uniformly mixed, in every direction on a plane. Next, the columns 2 are set in a state where their outer peripheries mutually overlap, and height, thickness and weight enough to resist against soil pressure are given to the wall 1, and the inside ground enclosed by the wall 1 is excavated. Thus since a support is unnecessary, a wide work space can be obtained, and ground work can be easily executed, and since an earth anchor need not extend to a bearing ground, the excavation can be made on an optional shape plane even when an obstacle exists, and moreover since the column is made by mixing the excavated soil and the filler, constructing cost can be reduced.

Load reduction on buried rigid pipes. load reduction on rigid culverts beneath high fills. long term behaviour. long-term behaviour of flexible large-span culverts

Abstract: A full-scale test with the imperfect ditch method is described. Expanded polystyrene is used as the compressible material. The material characteristics and the long-term behaviour of expanded polystyrene are well known. The disadvantages of using organic material are pointed out. The experimental results show that the average vertical earth pressures on the pipe were reduced to 43% of the overburden. The measured earth pressure are compared with results from the finite element program CANDE and results from a design method that is proposed. (A)

Method and apparatus for measuring earth pressure

Abstract: PURPOSE:To improve working environment by enabling the measurement of earth pressure without using any heavy earth pressure gauge. CONSTITUTION:A tension force works on cables 12 and 12 based on an earth pressure. A flat jack body 22 is pressed strongly between first and second plate materials 21 and 23 by the tension force. The pressure of a liquid sealed in the flat jack body 22 is measured with a manometer 33. A support value of the manometer 33 changes in proportion to the earth pressure.

Tunnel construction device

Abstract: PURPOSE:To make it possible to excavate mainly the whole rectangular section efficiently without leaving a portion of non-excavation by arranging cutting devices to the inside of a cylindrical body forming a line symmetrical figure with a shaft at an approximate right angle in the direction of the excavation to a direction at an approximate right angle in the direction of the excavation in a turnable manner. CONSTITUTION:When a cutting device driving motor 8 is driven, a rotary drum 4 is rotated, and a bedrock is excavated by cutting bits 6. At that time, if necessary, a viscosity given material is injected to excavated earth from a viscosity given material injection hole provided to the peripheral surface of the rotary drum 4, and it is so mixed with the excavated earth by cutting bit bearing members 19 or ribbon-like screw blades 20, etc., that plastic fluidity can be obtained. And, at the same time, a shield jack 15 is driven to push a cylindrical body 1 to make earth pressure generate, at the same time, the earth pressure is detected by an earth pressure gauge provided to a partition wall 1a, and a tunnel is constructed while controlling speed of an earth-moving screw conveyer 13 or speed of the shield jack 15 so that earth pressure becomes constant.