Showing papers on "Lateral earth pressure published in 1981"

An Introduction to Geotechnical Engineering

Abstract: This manual presents data on soil behaviour, with emphasis on practical and empirical knowledge, required by geotechnical engineers for the design and construction of foundations and embankments It deals with: index and classification properties of soils; soil classification; clay minerals and soil structure; compaction; water in soils (capillarity, shrinkage, swelling, frost action, permeability, seepage, effective stress); consolidation and consolidation settlements; time rate of consolidation; the Mohr circle, failure theories, and stress paths; shear strength of sands and clays Four appendices deal with the following: application of the "SI" system of units to getechnical engineering; derivation of Laplace's equation; derivation and solution of Terzaghi's one-dimensional consolidation theory; pore pressure parameters (TRRL)

Laboratory study of hydraulic fracturing

Abstract: Laboratory tests on Teton Dam soil were performed by increasing the water pressure in model bore holes and in simulated rock joints. The water pressure required to cause hydraulic fracturing was found to depend on soil density, water content, confining stress and test duration. On the basis of the test results it was hypothesized that: (1)Hydraulic fracturing is a weak link phenomenon, in that fracturing will occur in the least resistant soil subjected to increased water pressure; and (2)hydraulic fracturing can probably occur only in the presence of a discontinuity, within which the water pressure can act to create a wedging mechanism, thus creating tensile stresses in the soil.

Soils and Foundations

Abstract: 1. Formation of Natural Soil Deposits. 2. Engineering Properties of Soils. 3. Soil Exploration. 4. Soil Compaction and Stabilization. 5. Water in Soil. 6. Stress Distribution in Soil. 7. Consolidation of Soil and Settlement of Structures. 8. Shear Strength of Soil. 9. Shallow Foundations. 10. Pile Foundations. 11. Drilled Caissons. 12. Lateral Earth Pressure. 13. Retaining Structures. 14. Stability Analysis of Slopes. Answers to Selected Problems. Appendix: Conversion Factors. Index.

Friction capacity of piles driven into clay

Abstract: Several studies on axial pile capacity in clays have shown that the average frictional resistance, expressed as a fraction of the average undrained shear strength or average effective overburden pressure, decreases with increasing pile penetration. Procedures to compute shaft friction are reviewed, and the effect of pile length on the development of shaft friction on piles in clay is examined in terms of the relative pile-soil stiffness and lateral pile movements during installation. Correlations are developed to relate shaft friction coefficients α,β,λ, to pile length, relative pile-soil stiffness, and soil stress history. Procedures are recommended to compute the friction capacity of piles in clay.

Numerical identification of soil‐structure interaction pressures

Abstract: A numerical approach is presented for the ‘identification’ (or back calculation) of the earth pressure acting on embedded or retaining structures. The procedure is applicable to structures of any shape and requires a set of in situ measurements that may include displacements of points on the structure, values of concentrated forces, values of distributed loads at some locations, etc. Possible limiting values of the unknown loads, non-linear structural behaviour, varying accuracies of the input data are accounted for in the problem formulation. Depending upon the type of problem, the solution is reached by means of the unconstrained or constrained minimization of a suitably defined error function. As an example, the proposed approach is applied to the identification of the earth pressure acting on some typical geotechnical engineering structures.

Lateral pile response during earthquakes

Abstract: A nonlinear method for seismic soil-pile-structure interaction is presented. Primary features of the proposed method include a consistent approach to determine seismic p-y relationships and a liquefaction model that is suited to pore pressure evaluation for earthquake-type irregular loadings. The seismic- p-y relationships are determined from nonlinear stress-strain relations of soils, and include soil nonlinearity as well as pore pressure buildup effects around a pile. The performance and validity of the method were evaluated through an analysis of shaking table test on model soil-pile-structure systems. Using the proposed method, seismic response characteristics of an idealized offshore pile-supported structure at a sand site were analyzed. Results indicated that liquefaction as well as pore pressure bulidup around a pile can have a large impact on the response of pile-supported structures.

Total lateral surcharge pressure due to strip load

Abstract: The calculation of lateral surcharge pressure against a vertical retaining wall due to a point load, line load, and strip load is being performed using the modified forms of the Boussinesq's equations. For the strip load type of surcharge, only the equation for the unit lateral surcharge pressure is given. It is left to the user to evaluate the total lateral surcharge pressure by mechanical integration procedures which obviously are time-consuming. This paper is presented to show that a direct solution for the total lateral surcharge pressure can be derived by mathematical manipulation of the variables in the given equation for the unit lateral surcharge pressure. Simplified expressions for the location of the centroid of the total lateral surcharge pressure and the point of maximum unit lateral pressure are also derived to complete the analysis. Retaining wall structures supporting continuous wall footing, highway, and railroad loadings are practical examples in which strip load type of surcharge is applicable. The calculated total lateral surcharge pressure is then added to other lateral pressures such as earth pressure, water pressure, etc., for stability and structural analysis of the retaining wall structure. The use of the derived formulas will save the user time in computation of surcharge pressure involving the strip load type of surface load. The reader should note that the formulas are general solutions considered applicable to yielding or unyielding retaining wall structures with the soil wedge behind it either in the active or passive mode of failure depending on the given condition of the problem. (The complete derivation may be furnished by the author upon request). (Author)

Laboratory instrument for measuring lateral soil pressure and swelling pressure

Abstract: A new instrument which allows the measurement of lateral pressure and lateral swelling pressure of a soil sample in the laboratory, either with or without lateral strain, is presented. Results of tests carried out with this apparatus are discussed and compared with results of similar tests using other instruments.

Laterally loaded pile design

Abstract: A beam-bar finite element formulation of a laterally loaded pile problem is developed. The approach taken utilizes the beam on elastic foundation coefficient of subgrade reaction method. The three loading conditions of a lateral load or applied moment on a free-end pile and a lateral load applied to a fixed-end pile are analyzed for a range of soil strength variations with depth. Curves are developed which present the maximum values as a function of the soil-structure stiffness ratio. A design procedure with an example is given to show the use of these curves in the design of any laterally loaded pile system.

Lateral Stress Measurements in Direct Simple Shear Device

Abstract: Monitoring lateral stresses in a soil specimen during monotonic or cyclic shear tests significantly increases the amount of information obtained from these tests. A technique is described for interpreting lateral stress data during consolidation (the initial phase of either type of shear test) and determining the lateral stress level at the start of the shear test. In addition, the coefficient of lateral earth pressure at rest (K 0 ) is determined. The Norwegian Geotechnical Institute (NGI) Direct Simple Shear Device was used in this study. Lateral stress measurements were made with calibrated wire-reinforced membranes (acting as strain gages). Two undisturbed samples of soft marine clay were investigated: a Gulf of Mexico and a Gulf of Alaska sample. The samples were obtained from a depth of about one metre below the sea floor. Large vertical specimen strains were encountered even though the applied consolidation stresses were small (a maximum vertical stress of 0.518 kg/cm 2 ). The technique described includes methods for eliminating possible sources of substantial error at these low stress levels. The values of K 0 as determined from the lateral stress measurements agree well with values determined indirectly.

Field tests and new design procedure for laterally loaded drilled shafts in clay

Abstract: Lateral load tests were conducted on three drilled shafts in predominantly CH soil. Shaft sizes varied from 30 in. (760 mm) to 36 in. (910 mm) in diameter and 15 ft. (4.6 m) to 20 ft. (6.1 m) in length. Loads were applied incrementally at a point 2.6 ft (790 mm) above the ground surface. Duration of the tests was 57, 24 and 205 days. Measurements of lateral earth pressure at various points along the length of the shaft, displacement near the ground surface, and rotation in the plane of loading were obtained for each increment of load. Additional data on five shafts tested under similar conditions were obtained from the literature. Based upon an analysis of the test data, the ultimate lateral load capacity of a rigid shaft was defined as the load required to produce a shaft rotation of 2 degrees. This definition was used to obtain an empirical correlation of rotation with lateral load. A correlation of the coefficient of ultimate resistance at the groundline N sub p, with soil shear strength was also made. A design procedure utilizing the two correlations was developed. Several analytical methods described in the literature were used to calculate the capacity of the eight test shafts. The results were compared with computed capacities obtained by use of the design procedure developed for this research study. (FHWA)

Construction of retaining wall

Abstract: PURPOSE:To easily construct a retaining wall by a method in which a backing material having an interval shearing strength is used for the retaining wall in such a way that the backing material is in an independent or similar state in order to alleviate the retaining wall of soil pressure being burdened. CONSTITUTION:The first stage wall 7 is constructed by vertically erecting plural concrete plates in a trench having a width corresponding to the thickness of the wall 7, excavated underground 1, and nuts are temporarily fixed to each concrete plate by piercing the frontal ends of anchors 8 through the concrete plates. Then, the first stage back-filling soil 12 having an internal shearing strength is supplied to the back side of the wall 7 while compacting it. When the back- filling soil 12 reaches the fitting level of the anchors 8, anchor plates 11 are driven into the soil 12, and then the nuts 10 are clamped to fix the plates 8 to the wall 7. Again, the soil 12 is supplied to bury the anchors 8 in the soil 12. Then, the second stage wall 7 is provided lapjointedly with the wall 7 in the back side of the wall 7 and on the soil 12 of the first stage retaining wall portion 2. In the same way, the second stage retaining wall portion 3 is formed, followed by the third-fifth retaining wall portions 4-6 by the same method.

Stabilization of soft ground by construction of underground wall

Abstract: PURPOSE:To suppress the settling of the ground which is hazardous to construction work and impart resistance high enough to withstand soil pressure and sliding power upon the ground by injecting a grout compositin to solidify its surrunding soil into the ground while regulating it. CONSTITUTION:At several points of soft ground to be stabilized, a soil survey, e.g., sounding, etc., is carried out in advance. Then, a value serving as an indication for the fortification of ground at a given depth in a desired portion of soft ground is obtained, and according to the wideness of the objective ground, sheet pipes or piles 1 are driven in single or plural rows into a supporting layer 2. Then, a grout composition composed mainly of cement milk is injected inbetween and around the piles and then solidified.

Soil-Pipe Interaction and Pipeline Design

Abstract: The problem of steel pipe bend design with and without lateral soil restraint is studied, and the effect of backfill soil deformation on the bend design is postulated. Studies show that a finite element model utilizing nonlinear soil properties is superior to conventional earth pressure theories and can result in an economic design. The effect of backfill type and the depth of soil cover in resisting the outward radial forces at bend locations are examined. Practical design and construction recommendations are presented.

Identification of earth pressure on tunnel liners

Abstract: A numerical procedure is presented for the "identification" or back calculation, of the earth pressure acting on tunnel liners on the basis of in situ measurements performed on the full scale structure. The "optimal" earth pressure distribution is back calculated by minimizing an error function defined on the basis of the inverse equations of the structural problem and of a series of additional conditions. The results obtained by applying the procedure to a significant problem are presented.

Behavior of an Overconsolidated Sensitive Clay in Drained K 0 -Triaxial Tests

Abstract: In order to understand the mechanisms that govern the development of lateral stresses in overconsolidated clay deposits, specimens of an undisturbed sensitive clay from Lachute (P.Q.) were tested in a triaxial chamber under K 0 -conditions. The results of these tests show that the response of the clay can be divided into three distinct phases of deformation. At low stress levels, the clay behaves as an elastic material. At intermediate stress levels, the clay behaves as a plastic material. At high stress levels, the clay becomes normally consolidated. The experimental data are used to establish a model describing the mobilization of lateral stresses, and it is shown that the in situ coefficient of earth pressure at rest cannot be determined by laboratory testing. The theory of anisotropic elasticity is used to predict the development of lateral stresses and pore water pressures at low stress levels. Predicted values are compared with those measured underneath the St. Alban (P.Q.) test fills.

Frozen earth pressure measuring apparatus

Abstract: PURPOSE:To measure a frozen earth pressure without any concentrated stress when it has a high rigidity by means of an earth pressure meter provided with a load cell between a reaction plate and a pressure receiving plate of an earth pressure measuring device. CONSTITUTION:When the subsoil is cooled by a cold heat of a liquid stored in an underground tank, it begins to be frozen from the external surface of a wall body 1. As the frozen earth 2 becomes thick, a pressure of a frozen earth exerts on the wall body 1 with a freezing expansion and further on a pressure receiving plate 6 of an earth pressure meter 4. In this process, a load cell will be compressed slightly more than the wall body under a pressure. But a slight projection of the pressure receiving plate 6 from the external surface of the wall body makes the rigidity of the wall body slightly larger than that of the earth pressure meter when the pressure exerts thereon thereby relaxing the concentrated stress on the wall body.

Earth pressure distribution in subway structures retaining tamped backfills - an assessment

Abstract: This paper reports the details of measurements taken behind a pedestrian subway near Anna Salai (Mount Road) Madras. The measured values are compared with those predicted by theoretical solutions and the reasons for the difference between the two are analysed. The investigation reveals that the method of hand tamping of the backfill material is one of the main reasons for the greater earth pressure magnitudes obtained from the field measurements. The paper also emphasises the need for more such future measurement with the sole aim of standardising the pattern of pressure distribution for boxlike structure, retaining tamped backfills, so that a rational design practice can be evolved in future. (TRRL)

Field measurements of earth pressure on a cantilever retaining wall

Abstract: Field observations of the performance of an 11-ft (3.4-m) high cantilever wall on clay soil retaining a highway embankment in Houston, Texas were obtained. Measurements of wall translation and tilt, lateral earth pressure on the back face and bearing pressure on the footing were made periodically throughout a one-year period. Data acquisition began immediately after wall construction; data were obtained before, during and after placement of the select sand backfill. Measured lateral and bearing pressures were compared with calculated values obtained by published analytical methods, including the well-known Rankine and Coulomb theories of lateral earth pressure. Measured lateral pressures were integrated to obtain the resultant force on the wall. The resultant force was also computed by Culmann's graphical method for comparison with the value obtained by integration. Surcharge effects were studied by comparing the pressures and forces acting on the wall before and after placement of clay above the select sand backfill. (FHWA)