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Showing papers on "Lateral earth pressure published in 1997"


Book
01 Jan 1997
TL;DR: One-dimensional compression and consolidation of clays has been studied in this paper, where the authors present a simple model for the behavior of clay soils in one-dimensional k-compression and consolidation.
Abstract: Origin and classification of soils Introduction: what is soil mechanics? Structure of the earth Origin of soils Soil mineralogy Phase relationships for soils Unit weight Effective stress Particle size distributions Soil filters Soil description Index tests and classification of clay soils Compaction Houses built on clay Key points Self-assessment and Learning Questions Origins and mineralogy of soils Phase relationships, unit weight and calculation of effective stresses Particle size analysis and soil filters Index tests and classification Compaction Notes References Soil strength Introduction Stress analysis Soil strength Friction Shearbox or direct shear apparatus Presentation of shearbox test data in engineering units Volume changes during shear Critical states Peak strengths and dilation Shearbox tests on clays Applications Stress states in the shearbox test Simple shear apparatus Key points Self-assessment and learning questions Shearbox test Development of a critical state model Determination of peak strengths Use of strength data to calculate friction pile load capacity Stress analysis and interpretation of shearbox test data References Groundwater flow and control Introduction Pore water pressures in the ground Darcy's law and soil permeability Laboratory measurement of permeability Field measurement of permeability Permeability of laminated soils Mathematics of groundwater flow Plane flow Confined flownets Calculation of pore water pressures using flownets Quicksand Unconfined flownets Distance of influence Soils with anisotropic permeability Zones of different permeability Boundary conditions for flow into drains Application of well pumping formulae to construction dewatering Numerical methods Groundwater control Unsaturated soils Key points Self-assessment and learning questions Laboratory measurement of permeability fluidisation layered soils Well pumping test for field measurement of permeability Confined flownets and quicksand Unconfined flownet Flownets in anisotropic soils Notes References One-dimensional compression and consolidation Introduction and objectives One-dimensional compression: the oedometer test One-dimensional consolidation Properties of isochrones One-dimensional consolidation: solution using parabolic isochrones Determining the consolidation coefficient cv from oedometer test data Application of consolidation testing and theory to field problems One-dimensional consolidation: exact solutions Radial drainage Limitations of the simple models for the behaviour of soils in one-dimensional compression and consolidation Key points Self-assessment and learning questions Analysis and interpretation of one-dimensional compression test data Analysis of data from the consolidation phase Application of one-dimensional compression and consolidation theory to field problems Notes References Triaxial test and soil behaviour Introduction Triaxial test Stress parameters Stress analysis of the triaxial test Determining the effective angle of shearing resistance phi' from triaxial shear tests Undrained shear strengths of clay soils Isotropic compression and swelling Specimen preparation by one-dimensional compression and swelling: K consolidation Conditions imposed in shear tests Critical states Yield State paths during shear: normally consolidated and lightly overconsolidated clays Peak strengths Residual strength Sensitive soils Correlation of critical state parameters with index tests Creep Anisotropy Unsaturated soils Critical state model applied to sands Non-linear soil models Repeated or cyclic loading Key points Self-assessment and learning questions Interpretation of triaxial test results Determination of critical state and Cam clay parameters Analysis and prediction of state paths using Cam clay concepts Notes References Calculation of soil settlements using elasticity methods Introduction Selection of elastic parameters Boussinesq's solution Newmark's chart and estimation of vertical stress Settlements due to surface loads and foundations Influence factors for stress Standard solutions for surface settlements on an isotropic, homogeneous, elastic half-space Estimation of immediate settlements Effect of heterogeneity Cross-coupling of shear and volumetric effects due to anisotropy Key points Self-assessment and learning questions Determining elastic parameters from laboratory test data Calculation of increases in vertical effective stress below a surface surcharge Calculation of increases in vertical effective stress and resulting soil settlements Use of standard formulae in conjunction with one-dimensional consolidation theory References Plasticity and limit equilibrium methods for earth pressures and retaining walls Engineering plasticity Upper and lower bounds (safe and unsafe solutions) Failure criteria for soils Retaining walls Calculation of limiting lateral earth pressures Development of simple stress field solutions for a propped embedded cantilever retaining wall Soil/wall friction Mechanism-based kinematic and equilibrium solutions for gravity retaining walls Reinforced soil walls Compaction stresses behind backfilled walls Key points Self-assessment and learning questions Calculation of lateral earth pressures and prop loads Stress field limit equilibrium analysis of an embedded retaining wall Mechanism-based limit equilibrium analysis of retaining walls Reinforced soil retaining walls Compaction stresses References Foundations and slopes Introduction and objectives Shallow strip foundations (footings): simple lower bound (safe) solutions Simple upper bound (unsafe) solutions for shallow strip footings Bearing capacity enhancement factors to account for foundation shape and depth, and soil weight Shallow foundations subjected to horizontal and moment loads Simple piled foundations: ultimate axial loads of single piles . -crit or-peak Pile groups and piled rafts Lateral loads on piles Introductory slope stability: the infinite slope Analysis of a more general slope Laterally loaded piles for slope stabilisation Key points Self-assessment and learning questions Shallow foundations Deep foundations Laterally loaded piles Slopes References In-ground retaining structures: embedded walls and tunnels Introduction and objectives Earth pressure coefficients taking account of shear stresses at the soil/wall interface Limit equilibrium calculations for embedded retaining walls and ultimate limit state design Calculation of bending moments and prop loads: serviceability limit states Embedded walls retaining clay soils Geostructural mechanism to estimate wall movements Effect of relative soil: wall stiffness Strip loads Multi-propped embedded walls Tunnels Key points Self-assesment and learning questions Embedded retaining walls and ULS design Tunnels Note References Calculation of improved bearing capacity factors and earth pressure coefficients using plasticity methods Introduction and objectives Stress discontinuities and their use to calculate improved bearing capacity factors for a shallow foundation subjected to a vertical load: effective stress (phi') analysis Stress discontinuities and their use to calculate improved bearing capacity factors for a shallow foundation subjected to a vertical load: total stress (tauu) analysis Application to stress analysis Shallow foundations subjected to inclined loads Calculation of earth pressure coefficients for rough retaining walls Sloping backfill Wall with a sloping (battered) back Improved upper bounds for shallow foundations Key points Self assesment and learning questions Bearing capacity of foundations Retaining walls and earth pressures References Site investigation, in situ testing and modelling Introduction and objectives Site investigation In situ testing Modelling Ground improvement Key points Self-assessment and learning questions In situ testing Modelling Ground improvement Notes References Index

208 citations


Journal ArticleDOI
TL;DR: In this paper, the authors conducted eight centrifuge model experiments to study the mechanism of liquefaction-induced settlement of a shallow foundation, as well as the effectiveness of sand densification by vibrocompaction under the footing.
Abstract: Investigators conducted eight centrifuge model experiments to study the mechanism of liquefaction-induced settlement of a shallow foundation, as well as the effectiveness of sand densification by vibrocompaction under the footing. Two series of model tests were conducted with a surface circular footing placed on a medium-dense saturated sand layer overlying an impervious rigid base. Horizontal shaking simulating an earthquake was used to excite the base of each model in flight; in all cases this shaking liquefied the sand in the free field. The first series of tests concentrated on the effect of the depth of soil compacted under the foundation on the footing acceleration and settlement. Investigators discovered that as the compaction depth increased and approached the total thickness of the soil deposit, the footing acceleration during shaking increased and its settlement decreased. The soil was not densified in the second series of tests; this series focused on the effect of soil permeability on pore pressure buildup and footing settlement. Investigators learned that as the soil becomes more impervious, significant negative excess pore pressures develop under the footing during shaking, and the contribution of postshaking foundation settlement increases while the total foundation settlement does not change significantly. Building settlements observed after two earthquakes in liquefied areas of Niigata, Japan in 1964, and Dagupan, Philippines in 1990, are discussed. Comparisons are made between the field observations and the centrifuge results.

206 citations


Journal ArticleDOI
TL;DR: In this paper, the lateral response of vertical piles subjected to lateral soil movements is computed via a simplified boundary-element analysis, using a specified free-field soil movement profile, which can generally give a satisfactory prediction of the pile response, as demonstrated via a study of some model tests and published case histories.
Abstract: This paper presents a theoretical procedure for analyzing the lateral response of vertical piles subjected to lateral soil movements. The lateral pile response is computed via a simplified boundary-element analysis, using a specified free-field soil movement profile. For pile groups, the group effect may need to be preassessed via a finite-element analysis. Based on an appropriate assessment of the lateral soil movement, soil Young's modulus and limiting pile-soil contact pressure, the present method can generally give a satisfactory prediction of the pile response, as demonstrated via a study of some model tests and published case histories. For practical convenience, some elastic solutions have been generated using the present boundary-element program and are presented in chart form. These design charts tend to give an upper-bound estimation of the maximum pile bending moment and pile head deflection, although a close estimation may be obtained for small soil movements.

146 citations


Journal ArticleDOI
TL;DR: In this article, a critical evaluation of the response to horizontal ground shaking of flexible cantilever retaining walls that are elastically constrained against rotation at their base is made, where the wall response quantities examined include the displacements of the wall relative to the moving base, the wall pressures, and the associated shears and bending moments.
Abstract: A critical evaluation is made of the response to horizontal ground shaking of flexible cantilever retaining walls that are elastically constrained against rotation at their base. The retained medium is idealized as a uniform, linear, viscoelastic stratum of constant thickness and semi-infinite extent in the horizontal direction. The parameters varied include the flexibilities of the wall and its base, the properties of the retained medium, and the characteristics of the ground motion. In addition to long-period, effectively static excitations, both harmonic base motions and an actual earthquake record are considered. The response quantities examined include the displacements of the wall relative to the moving base, the wall pressures, and the associated shears and bending moments. The method of analysis used is described only briefly, emphasis being placed on the presentation and interpretation of the comprehensive numerical solutions. It is shown that, for realistic wall flexibilities, the maximum wall f...

114 citations


Journal ArticleDOI
TL;DR: In this article, a simple analysis method using a modified Coulomb's solution of active pressure was proposed to predict the lateral earth pressure at any wall displacement behind a rotating wall, where the deformation pattern and the associated mobilization of shearing resistance in the soil were considered in a simplified manner.
Abstract: Classical earth pressure theories are valid strictly for retaining walls subject to uniform free translation. Practically all retaining walls rotate, and movements of the wall could be restricted, particularly under working conditions. The lateral earth pressure on the wall often deviates from the fully active Coulomb value. There is a need for predicting the lateral earth pressure at any wall displacement behind a rotating wall. The finite element method (FEM) is capable of providing valid solutions of lateral pressures for different wall movements, but a simple alternative method has its practical value. This paper presents a simple analysis method using a modified Coulomb's solution of active pressure. The deformation pattern and the associated mobilization of shearing resistance in the soil as affected by the wall movement are considered in a simplified manner. Comparisons of calculated results with solutions from FEM and observations from model tests show that the method can provide a good prediction of lateral pressures for walls rotating about the base when proper distributions of mobilized shearing resistance and wall friction are used. For walls rotating about the top, the prediction is fair due to arching and the difference between assumed and observed rupture mechanisms.

79 citations


Journal ArticleDOI
TL;DR: In this paper, a flexible, grid-based, tactile pressure sensor allows pressure to be measured in up to 2288 (52 × 44) sensing locations with different shape and size of the measured area can vary with sensors up to 427 by 488 mm in size.
Abstract: A revolutionary technology is introduced enabling the measurement and presentation of normal stress distribution over an area in real time. A flexible, grid-based, tactile pressure sensor allows pressure to be measured in up to 2288 (52 × 44) sensing locations. The overall shape and size of the measured area can vary with sensors up to 427 by 488 mm in size. Pressure ranges are possible up to 172 MPa (25 ksi). The system was originally developed for dental purposes and has been used in other medical and mechanical applications as well. The implementation of the system is complex due to three factors: (a) the measurements are relative and hence absolute calibration is required; (b) the measurements are carried out simultaneously at a large number of points, and a calibration system calls for the development of “known” conditions at each point; and (c) the novel technology makes use of new principles and materials that can be influenced by loadrate, post-loading effects, creep, and hysteresis in addition to unfamiliar problems like trapped air. The preliminary examination of the technology for geotechnical applications is introduced through tests with ideal granular material. A calibration system was developed, and the sensors were examined through various loading and unloading rates as well as unchanging pressure conditions. The mean stress measurement depends on the pressure application sequence (stress history) with overall high accuracy compared to existing intruding soil pressure measurement techniques. The ability to examine stress variations over an area in real time is unmatched by any other existing means. The measurements of stresses developed along the front boundary of an interfacial shear device are used for demonstrating the system's application.

62 citations


Journal ArticleDOI
TL;DR: In this article, the experimental data of earth pressure acting against a vertical rigid wall, which moved away from or toward a mass of dry sand with an inclined surface, was used to investigate the variation of earthpressure induced by the translational wall movement.
Abstract: This paper presents experimental data of earth pressure acting against a vertical rigid wall, which moved away from or toward a mass of dry sand with an inclined surface. The instrumented retaining-wall facility at National Chiao Tung University (NCTU) Taiwan, was used to investigate the variation of earth pressure induced by the translational wall movement. Based on experimental data, it has been found that the earth-pressure distributions are essentially linear at each stage of wall movement. Both the wall movement required for the backfill to reach an active state and the wall movement needed for the backfill to reach a passive state increase with an increasing backfill inclination. The experimental active and passive earth-pressure coefficients for various backfill sloping angles are in good agreement with the values calculated by Coulomb's theory. It may not be appropriate to adopt the Rankine theory to determine either active or passive earth pressure against a rigid wall with sloping backfill.

57 citations


Journal ArticleDOI
TL;DR: In this article, Terzaghi presented a graphical solution to the lateral earth pressure problem of cohesive backfill with an inclined surface, which becomes tiresome for solving practical retaining wall pro...
Abstract: Terzaghi presented a graphical solution to the lateral earth pressure problem of cohesive backfill with an inclined surface. This procedure becomes tiresome for solving practical retaining wall pro...

47 citations


Journal ArticleDOI
TL;DR: In this paper, the performance of a tiedback excavation with a soil mixed wall in Boston where underlying marine clay was stabilized by deep soil mixing (DSM) and jet grouting was evaluated.
Abstract: This paper describes the performance of a tiedback excavation with a soil mixed wall in Boston where underlying marine clay was stabilized by deep soil mixing (DSM) and jet grouting. Lateral and vertical soil displacements, soil strains, and tieback loads are evaluated. The interaction between the retained soil and a reinforced concrete box culvert, supported on drilled shafts, is described. Piezometer measurements behind the wall are summarized. They show pore-water pressures in marine clay substantially less than the hydrostatic pressures assumed in design.

33 citations


Journal ArticleDOI
TL;DR: In this article, a method of slices satisfying all the conditions of statical equilibrium has been developed to deal with the problem of determination of passive earth pressure over a retaining wall in sand.
Abstract: A method of slices satisfying all the conditions of statical equilibrium has been developed to deal with the problem of determination of passive earth pressure over a retaining wall in sand. A method similar to that of Morgenstern and Price 1 which was used to solve the stability of slopes, has been followed. The earth pressure coefficients with the proposed methodology have been computed for a vertical retaining wall for both positive and negative wall friction angle. Also examined is the variation of the interslice shear force between the retaining wall and the Rankine Passive boundary. Due to complete satisfaction of the equilibrium conditions, the method generates exactly the same earth pressure coefficients as computed by using Terzaghi's overall limit equilibrium approach.

22 citations


Journal ArticleDOI
R. Earl1
TL;DR: In this paper, a new approach to assess the compactive nature of soils is proposed based on results from plate sinkage tests in conjunction with those from confined compression tests, which provides information on the strength of soil and the way in which soils behave under load.

Journal Article
TL;DR: In this paper, an 800-mm pipe was built on a cushion of expanded polystyrene under an embankment fill of 9.3 m. In a pilot study measurements were taken of soil-pipe contact earth pressures around the circumference of the pipe, vertical earth pressures in the soil above the crown, relative diameter changes of pipe in the vertical and the horizontal directions, and pipe settlements into the cushion.
Abstract: In a project involving the construction of a new link of European Freeway E18, an 800-mm pipe was to be founded on a cushion of expanded polystyrene under an embankment fill of 9.3 m. In a pilot study measurements were taken of soil-pipe contact earth pressures around the circumference of the pipe, vertical earth pressures in the soil above the crown, relative diameter changes of the pipe in the vertical and the horizontal directions, and pipe settlements into the cushion. The design of the complete structure was partly done by using the active design program SPIDA (Soil Pipe Interaction Design and Analysis). The results indicate that the safety margin in the design was greater than first expected because the reinforced standard pipe, designed for only 5 m of fill, was uncracked, even though the height of fill was 9.3 m. The measured deformations of the pipe were smaller than those expected for the concrete to crack. The earth pressure measurements showed a pronounced soil arching effect in the soil above the pipe.

Journal Article
TL;DR: In this article, the concept of the plasticity theory is employed in a hyperbolic model and the strength and yield functions derived based on Lo's equation are used to differentiate Young's moduli between primary loading and unloading/reloading states.
Abstract: The original hyperbolic model uses the stress level criterion to differentiate the state between the primary loading and unloading/reloading states. This simple stress level criterion cannot take into account the rotation of principal stresses or the anisotropic soil behavior. In this study, the concept of the plasticity theory is employed in a hyperbolic model. The strength and yield functions derived based on Lo's equation are used to differentiate Young's moduli between primary loading and unloading/reloading states. The strength criterion can estimate the undrained shear strengths in various directions with good accuracy, based on the laboratory test results in the literature. An excavation case with complete field observations is then studied using the finite element method with the modified and original hyperbolic models. Analysis results show that the proposed method can give better prediction for wall deflection, ground surface settlement, wall bending moment, total lateral earth pressure and bottom heave, compared with the original model. (A)

Journal ArticleDOI
TL;DR: In this paper, the analysis of deep rotational stability is described, whereby limiting equilibrium computations are performed for circular sliding surfaces and dimensionless charts are presented to estimate safety factors and identify the centers of rotation of critical slip circles.
Abstract: This paper addresses the base stability of excavations in deep, relatively weak deposits of clay that are supported by earth-anchored tiebacks. Under these conditions there may be the potential for a circular sliding surface to propagate outside the anchor bond zone and daylight to show in the basal portion of the cut. In this paper the analysis of deep rotational stability is described, whereby limiting equilibrium computations are performed for circular sliding surfaces. Dimensionless charts are presented to estimate safety factors and identify the centers of rotation of critical slip circles. The suitability of the method is assessed by means of a case history involving an unstable excavation in Boston marine clay. The soil conditions and ground movement measurements at the site are presented, followed by the results of limiting equilibrium and finite-element analyses. Deep rotational stability is shown to be one of the most important failure mechanisms for tiedback excavations in relatively weak clay, and the dimensionless charts presented in this work are shown to provide a good estimate of the stability difficulties experienced at the case history site.

DOI
05 Aug 1997
TL;DR: In this paper, a concept for the design of high water protection (HWP) walls under storm surge conditions has been developed and is applied to the geometry found in the harbour of Hamburg, Germany.
Abstract: A concept for the design of high water protection (HWP) walls under storm surge conditions has been developed and is applied to the geometry found in the harbour of Hamburg, Germany. However, the design methods used have been generalized so that they may be used for a wide range of cases with similar geometries. Many gaps in standard design formulae have been filled by developing engineering approaches or formulae as reflection by steep berms, new breaker criterion, design formulae for impact breakers, reduction of loads by overtopping and soil pressure distribution in front of the wall.

Journal ArticleDOI
TL;DR: In this article, a simple theory for calculating the magnitude of vertical shear loads on non-moving walls is presented, and typical results from the theory are discussed, and a companion paper presents the results of finite element calculations, case history data, and recommendations for retaining wall design.
Abstract: Retaining walls that do not move are customarily designed based on the assumption of at-rest conditions, with no consideration of vertical shear loads applied by the backfill. However, field and laboratory measurements have shown that vertical shear loads do act on nonmoving walls. A simple theory for calculating the magnitude of vertical shear loads on nonmoving walls is presented in this paper, and typical results from the theory are discussed. A companion paper presents the results of finite-element calculations, case history data, and recommendations for retaining wall design.

Journal ArticleDOI
TL;DR: In this article, a practical numerical model for analysis of flexible retaining walls is described, which fits between traditional limit equilibrium methods and full finite element approaches; it overcomes many of the limitations associated with the former but is not equipped with the versatility offered by the latter.
Abstract: A practical numerical model is described for analysis of flexible retaining walls. In terms of capabilities, the model fits between traditional limit equilibrium methods and full finite element approaches; it overcomes many of the limitations associated with the former but is not equipped with the versatility offered by the latter. Using an approach similar to that adopted in boundary-element based models, the wall stiffness is represented by a series of elastic beam elements whose stiffness is combined with that of the prestressed struts and the soil to form, the overall stiffness matrix. The stiffness matrix of the soil is obtained by inversion of flexibility matrices generated by interpolation and sealing of flexibility matrices calculated for a simplified soil model using finite element methods. The soil behaves linearly elastically, as long as the pressures correspond to stress levels lying between the limits. Where the lateral displacement of the wall corresponds to a pressure outside of these allow...

Journal ArticleDOI
TL;DR: In this paper, an 800mm pipe was built on a cushion of expanded polystyrene under an embankment fill of 9.3 m. The results indicated that the safety margin in the design was greater than first expected because the reinforced standard pipe, designed for only 5 m of fill, was uncracked.
Abstract: In a project involving the construction of a new link of European Freeway E18, an 800-mm pipe was to be founded on a cushion of expanded polystyrene under an embankment fill of 9.3 m. In a pilot study measurements were taken of soil-pipe contact earth pressures around the circumference of the pipe, vertical earth pressures in the soil above the crown, relative diameter changes of the pipe in the vertical and the horizontal directions, and pipe settlements into the cushion. The design of the complete structure was partly done by using the active design program SPIDA (Soil Pipe Interaction Design and Analysis). The results indicate that the safety margin in the design was greater than first expected because the reinforced standard pipe, designed for only 5 m of fill, was uncracked, even though the height of fill was 9.3 m. The measured deformations of the pipe were smaller than those expected for the concrete to crack. The earth pressure measurements showed a pronounced soil arching effect in the soil above...

Journal ArticleDOI
TL;DR: In this paper, a kinematic elasto-plastic soil model incorporating a Lade-Duncan failure criterion is used to calculate modified active and passive earth pressure coefficients for retaining walls.

Journal ArticleDOI
TL;DR: In this paper, a simple design procedure is developed to consider vertical shear forces in non-moving retaining walls, and it is shown that significant economies can result from consideration of vertical hear forces.
Abstract: Massive concrete walls constructed on rock foundations, as well as other nonmoving retaining walls, are customarily designed for at-rest earth pressures. Vertical shear loads applied by the backfill are usually not considered in design of nonmoving walls, even though many field and laboratory measurements have shown that such loads exist. Vertical shear loads can be very beneficial for stability of retaining walls, because they provide restoring moments to counteract overturning moments from lateral earth loads. In this paper, model test results and case history data are reviewed, the results of finite-element calculations are presented, and a simple design procedure is developed. It is shown that significant economies can result from consideration of vertical shear forces in design of nonmoving retaining walls.

Journal ArticleDOI
TL;DR: In this article, a mathematical model is presented for predicting the soil forces acting on concave agricultural discs operating with both disc and tilt angles, based on the basis that the curved cutting and scrubbing zones of the disc can be transformed into equivalent plane cutting surfaces.

Journal ArticleDOI
TL;DR: In this article, two types of commercially available dynamic earth pressure cells were tested to determine their suitability for measuring traffic-induced stresses in subgrade, and the main consideration was how well the gauges could be calibrated for accurate representation of soil stresses.
Abstract: Two types of commercially available dynamic earth pressure cells were tested to determine their suitability for measuring traffic-induced stresses in subgrade. The main consideration was how well the gauges could be calibrated for accurate representation of soil stresses. Tests were conducted with fluid pressure applied directly to the cells and with cells buried at various depths in a soil test chamber. The effects of soil type, proximity of adjacent cells, major principal stress direction, and temperature were investigated. Results indicate linearity, hysteresis, sensitivity, conformance, and accuracy. The two cells performed differently, but one was much more accurate than the other.

Journal ArticleDOI
TL;DR: In this paper, a generalized limit equilibrium method was developed by using the variational technique, and the fundamental simultaneous equations finally obtained define the critical limit state, and its corresponding earth pressure on a rigid earth-retaining wall.
Abstract: Based on a combination of the conventional limit equilibrium approach and Lagrange's indeterminate multiplier procedure, a generalized limit equilibrium method is developed by using the variational technique. The fundamental simultaneous equations finally obtained define the critical limit state, and its corresponding earth pressure on a rigid earth-retaining wall is established. The developed formulations are verified by comparing the computed results with those computed by traditional approaches that are based on the limit condition in the backfill. Numerical results are given to demonstrate the present method. Comments are made relating this method to the most widely used methods in design practice.

Patent
26 Nov 1997
TL;DR: In this paper, a process for supporting facings and the associated groundwater in advance working systems, especially with shields operated by earth pressure for the construction of tunnels and for micro-tunnelling, is described.
Abstract: A process for supporting facings and the associated groundwater in advance working systems, especially with shields operated by earth pressure for the construction of tunnels and for micro-tunnelling, in which the worked soil in the earth pressure chamber is mixed with a fluidising medium (I) and a pressure opposing the groundwater pressure is created by taking off the mixture. Medium (I) is a gel which reduces the permeability of the soil, and the soli/gel mixture is obtained by mixing and agitating in the working space or the feed screw.

Journal ArticleDOI
TL;DR: In this article, a numerical method based on the smeared shear band technique is presented for the localized deformation analysis, which can capture the progressive failure characteristics of the soil mass efficiently.

Patent
31 Mar 1997
TL;DR: In this article, the earth and sand excavated by the cutter head of a shield machine are discharged from a pressure chamber 5 on a screw conveyor in a cylindrical casing 7 by bending the middle section of the casing 7 and another plug zone 9B is also provided between a downstream side screw 8B and an opening/closing gate 10.
Abstract: PROBLEM TO BE SOLVED: To discharge earth and sand while the facing collapsing earth pressure in a pressure chamber is secured by providing a resistant member in a plug zone in a casing for discharging earth and sand and controlling the projecting amount of the resistant member in accordance with the properties of dug earth and sand. SOLUTION: The earth and sand excavated by the cutter head 3 of a shield machine are discharged from a pressure chamber 5 on a screw conveyor in a cylindrical casing 7. A plug zone 9A is provided by bending the middle section of the casing 7 and another plug zone 9B is also provided between a downstream-side screw 8B and an opening/closing gate 10. The frictional resistance of the earth and sand is reduced by protruding resistance plates into the zones 9A and 9B from long holes formed through the top and bottom of the casing 7. Therefore, the earth pressure in the pressure chamber 5 can be secured.

Patent
17 Jan 1997
TL;DR: In this paper, the authors proposed a method to accurately measure earth pressure even without increasing the mechanical assembly accuracy of an earth pressure meter by providing a pressure reception part and a pressure detection part.
Abstract: PROBLEM TO BE SOLVED: To accurately measure earth pressure even without increasing the mechanical assembly accuracy of an earth pressure meter by providing a pressure reception part and a pressure detection part. SOLUTION: When such pressure as earth pressure is applied to the entire surface of a pressure reception part 5 vertically, the pressure reception part 5 is recessed along an axial line L of a case body 3, thus shifting the short sides of a pressure detection part 12 mutually in parallel direction and hence curving a distorted part. The amount of distortion is transferred to a strain gauge 4 and is taken out externally from a cable 20 as an electrical signal corresponding to the amount of distortion. Even if such pressure as earth and sand is applied to the pressure reception part 5 in cantilever type, the reception part 5 vertically drops along the body 3 so that the detection part 12 is distorted and a strain gauge 14 can accurately detect the earth pressure. Also, a load cell for constituting the detection part 12 has a high sensitivity and improved linearity and is less subjected to the influence of an eccentric load.

Journal ArticleDOI
TL;DR: In this article, the authors describe the design and construction of reinforced cantilevered retaining walls and two case studies of retaining wall failures are presented, one due to a reduction in lateral support and the other due to an increase in lateral pressure from the Northridge earthquake.
Abstract: The purpose of this paper is to describe the design and construction of reinforced cantilevered retaining walls. Two case studies of retaining wall failures are presented. For the first case, the wall failed as a result of a reduction in lateral support. In the second case, the wall was damaged as a result of the increase in lateral pressure from the Northridge earthquake. A cantilevered retaining wall must have an adequate factor of safety for sliding and overturning, and have a footing bearing pressure less than the allowable bearing pressure. Two other common reasons for the failure of cantilevered retaining walls are using on-site soil and generating excess pressures during backfill compaction. Using on-site soil may lead to failure because the soil may not have the shear strength or permeability properties assumed during the wall design stage. To prevent damage to the wall from excess compaction pressures, lightweight hand-operated equipment or bobcats should be used for backfill compaction.

01 Jan 1997
TL;DR: In this article, a series of tests performed on a multi-span brick arch at the University of Edinburgh, Scotland is described, which is part of an ongoing investigation into soil/structure interaction in arch bridges.
Abstract: This paper describes a series of tests performed on a multi-span brick arch at the University of Edinburgh, Scotland. This research is part of an ongoing investigation into soil/structure interaction in arch bridges. The bridge is a 2m double span brick arch which is backfilled with dry silica sand. Instrumentation was installed to measure the normal and shear pressures on the arch extrados, the vertical pressure within the fill and the deflection of the brick arches. A patch and a strip load were applied to simulate the effects of a wheel and an axle load respectively. The soil pressures were compared to the Boussinesq method stress distribution and reasonable correlation has been obtained. In addition, the results are also compared to previous tests on a similar single span arch and it is shown that the behaviour is significantly different. For the covering abstract see ITRD E111699.

Journal Article
TL;DR: In this paper, the authors focus on measurement of shear strength for use in slope stability analyses, asserting that laboratory tests should be performed using the same range of pressures as will act on the shear plane in the field.
Abstract: A discussion of a paper with the aforementioned title by J.M. Duncan, published in this journal (Volume 122, Number 7, July 1996), is presented. The discussion focuses on measurement of shear strength for use in slope stability analyses, asserting that laboratory tests should be performed using the same range of pressures as will act on the shear plane in the field. It is maintained that when the failure envelope is curved, strength tests at high pressure may overestimate the strength of the soil at low pressure. Discussion is followed by closure from the author.