Showing papers on "Lateral earth pressure published in 1970"

The influence of strains in soil mechanics

Abstract: Synopsis The aims, during the past 20 years, of the Cambridge research programme in soil mechanics are outlined. The principal objective is to develop an understanding of the stress–strain behaviour of soils so that reliable predictions can be made concerning their load-deformation characteristics at all working loads, rather than only loads at failure, in practical problems. A superstructure and its foundation can then be designed as a unit. The pressing need for the study of the load-deformation behaviour of soils in mixed boundary value problems at model scale is emphasized. New versatile shear test equipment which can impose a wide range of stress and/or strain paths, together with non-destructive methods of checking the uniformity of the behaviour of specimens, are briefly described. Typical data are presented for one problem, illustrating the variation of the passive pressure on a retaining wall with the displacement of that wall into sand. A revised statement of the Mohr-Coulomb failure criterion i...

Limit analysis of plane problems in soil mechanics

Abstract: A computer method is developed for failure analysis of plane problems in soil mechanics. It is assumed that the soil obeys the Mohr-Coulomb failure criterion and that all stresses vary linearly within each element of a triangular mesh which spans the zone under investigation. An optimal statically admissible stress field corresponding to a lower bound solution is isolated by the method of linear programming. The method has been applied to several bearing capacity and earth pressure problems.

Relaxation of piles in sand and inorganic silt

Abstract: Many attempts have been made to modify the pile driving formulas to make them realistic in terms of modern driving practices and equipment None seems to have had a long-lasting impact on the engineering profession The driving impulse of a pile is always associated with a temporary remolding of surrounding soil, a zone of excessive pore water pressure and the dilatancy of dense fine sand For piles subjected to loading tests or under the load of a structure, there is no displacement in the soil; therefore, no remolding, no dilatancy and no excessive pore water pressure arise around the pile A review has been made of the basic mechanics relating to relaxation of pile resistance in dense fine sand or inorganic silt as well as the freeze of piles in soft clay or organic silt The pile resistance at the beginning of redriving can be used more effectively in representing the static capacity of a pile than that encountered in initial driving

Analysis of arching pressures in ideal elastic soil

Abstract: For the purpose of analysis of arching above a flexible structure the soil is considered a suitably-bounded rectangular prism with a strip of the bottom plane representing the structure undergoing settling in a uniform or a parabolic pattern. Solution is obtained by the elastic theory using the finite differences method. The principal compressive stress trajectories produced by differential settling indicate that an arch is formed in the overlying soil, abutting on both sides of the structure and transferring part of the load to those zones. Both magnitude and mode of the arching vary with depth of cover, beginning with two small separate local arches over the edges, through single arch with a saddle-shaped crown and ending with fully-developed arch which increases up to a fixed limiting size corresponding to geometric and elastic conditions. Increase in Poisson ratio strengthen the effect. A parabolic settling pattern (flexible structure) is associated with a smaller arching effect as part of the arch abuts on the edges of the structure itself, creating an “inner arch.”

Flexible plastic trash plate for a moldboard plow

Abstract: A trash plate for securement to a moldboard plow having a smooth soil engaging surface and made from a flexible plastic material. The trash plate having sufficient rigidity to withstand the soil pressure thereagainst and sufficient flexibility under said pressure to inhibit the adherence of soil thereto.

In Situ Strength of Rolled and Hydraulic Fill

Abstract: ROLLED AND HYDRAULIC FILL USUALLY HAVE ANISOTROPIC IN SITU STRENGTH CHARACTERISTICS. THE STRENGTHS ON HORIZONTAL AND VERTICAL PLANES IN AN ANISOTROPIC SOIL MAY BE EVALUATED BY VANE SHEAR TESTS WITH VANES OF DIFFERENT SHAPES. TESTS SHOW THAT THE IN SITU STRENGTH OF RECENTLY COMPACTED FILL IS ANISOTROPIC DUE TO IN-PLACE STRESS CONDITIONS, ALTHOUGH THE SOIL IS INTRINSICALLY ISOTROPIC. IN A 34-YEAR OLD EMBANKMENT, HOWEVER, THE IN SITU STRENGTH IS ISOTROPIC ALTHOUGH THE SOIL IS INTRINSICALLY ANISOTROPIC. THE IN SITU STRENGTH OF HYDRAULIC FILL IS ANISOTROPIC IN SUCH A WAY TO CORRESPND TO THE COEFFICIENT OF EARTH PRESSURE AT REST IN NORMALLY CONSOLIDATED SOIL. /AUTHOR/

Coefficient of earth pressure at rest as related to soil precompression ratio and liquid limit

Abstract: FROM EXPERIMENTS ON THREE TYPES OF SEATTLE CLAYS CONDUCTED IN A SPECIALLY DESIGNED STRESS METER, THE AUTHORS ESTABLISHED A RELATIONSHIP BETWEEN PRECOMPRESSION RATIO, PR, AND THE COEFFICIENT OF EARTH PRESSURE AT REST FOR OVERCONSOLIDATED SOILS WITH PR EQUAL TO OR LESS THAN 12. THIS RELATIONSHIP IS ALSO FOUND APPLICABLE TO SEVERAL SOIL TYPES TESTED BY OTHER RESEARCHERS. A UNIQUE RELATIONSHIP WAS OBSERVED BETWEEN THE COEFFICIENT OF EARTH PRESSURE AT REST FOR NORMALLY CONSOLIDATED SOILS AND THE LIQUID LIMIT OF THE SOILS TESTED BY THE AUTHORS AND OTHERS. A REDUCTION IN THE MAGNITUDE OF THE COEFFICIENT OF EARTH PRESSURE AT REST FOR OVERCONSOLIDATED SOILS AS A FUNCTION OF INCREASING DEPTH BELOW THE GROUND SURFACE IS INDICATED. ALSO, A RATIONALE FOR THE INCREASE OF THIS COEFFICIENT BECAUSE OF OVERCONSOLIDATION IS SUGGESTED. /AUTHOR/

Lateral thrust in frozen granular soils caused by temperature change

Abstract: FROZEN SOIL CONTAINING ICE, WHEN SUBJECTED TO A TEMPERATURE RISE, WILL EXERT PRESSURE AGAINST CONFINING BOUNDARIES. THE OBJECT OF THIS INVESTIGATION WAS TO MEASURE THE EXPANSIVE FORCE OF SAND-ICE SPECIMENS EXERTED ON RETAINING BOUNDARIES UNDER CONDITIONS APPROACHING THOSE IN A FULLY RESTRAINED FROZEN SAND LAYER. TWO DIFFERENT SANDS MADE INTO 140 SPECIMENS COMPOSED OF EOTHER SAN AND A VARIETY OF ICE CONTENTS WERE INCLUDED IN THE PROGRAM. THE STRAIN IN THE FROZEN SOIL WAS MEASURED BY MEANS OF BONDED RESISTANCE STRAIN GAGES EMBEDDED IN THE SAND-ICE SYSTE,. THE PRESSURE EXERTED BY THE FROZEN SAND WAS FOUND TO BE A FUNCTION OF FIVE VARIABLES: THE INITIAL SAMPLE TEMPERATURE, THE RATE OF INCREASE OF THE SAMPLE'S TEMPERATURE, TIME OF TEMPERATURE INCREASE, INITIAL POROSITY OF THE SOIL, AND DEGREE OF ICE SATURATION. EXPERIMENTAL RESULTS, WHEN PLOTTED IN THE FORM OF PRESSURE-TIME CURVES, SHOWED THE SAME TENDENCY FOR EVERY CURVE TO ATTAIN ITS MAXIMUM AFTER A CERTAIN TIME AND THEN DECREASE TO ZERO. THE VALUES OF MAXIMUM PRESSURE AND THE REQUIRED TIME TO REACH THIS PRESSURE WERE MEASURED FOR EACH EXPERIMENT, AND GRAPHS WERE DRAWN SHOWING THE INFLUENCE OF THESE PAPAMETERS ON THE MAXIMUM PRESSURE AND THE REQUIRED TIME. SUMMMARIZING THE EXPERIMENTALLY OBTAINED RESULTS, GENERAL EQUATIONS WERE DERIVED FOR THE FOLLOWING: (1) PRESSURE-TIME CURVES, (2) VALUES OF MAXIMUM PRESSURE DEVELOPED BY SAND-ICE LAYER, AND (3) PERIOD OF TIME REQUIRED BY THE SAND-ICE LAYER TO REACH ITS MAXIMUM PRESSURE. /AUTHOR/

Seismic pressure distribution in earth retaining walls

Abstract: AN INVESTIGATION IS DESCRIBED INTO THE EARTH PRESSURE DISTRIBUTION IN RETAINING WALLS SUBJECTED TO EARTHQUAKE FORCES. RUPTURE SURFACE IS TAKEN AS BEING LINEAR, AS ASSUMED BY COULOMB IN HIS WEDGE THEORY. EARTHQUAKE FORCE IS TAKEN AS THE EQUIVALENT STATIC HORIZONTAL FORCE OBTAINED BY MULTIPLYING THE MASS WITH THE SEISMIC COEFFICIENT ACTING AT THE CENTER OF THE MASS. SOLUTIONS ARE DEVELOPED FOR INCLINED RETAINING WALLS HAVING COHESIONLESS INCLINED BACKFILL. A COMPARISON IS MADE BETWEEN CALCULATED AND OBSERVED PRESSURE DISTRIBUTION. /TRRL/

Earth pressure acting on steel arch supports and lining concrete in swelling rocks

Abstract: AT THE "KAMUI" TUNNEL (L=4,523M), CONSTRUCTUED THROUGH A SERPENTINE FORMATION NOTED FOR SWELLING PHENOMENA, THE EARTH PRESSURE WAS MEASURED ON A LARGE SCALE TO INVESTIGATE THE CAUSE OF SWELLING, THE AMOUNT OF SWELLING, AND THE STRONG EARTH PRESSURE ANTICIPATED. THE MAIN ITEMS OF MEASUREMENT WERE THE STRESSES OCCURRING IN THE STEEL ARCH SUPPORTS AND THE LINING CONCRETE, THE EXTERNAL FORCE (I.E. THE EARTH PRESSURE) WORKING ON THE STEEL ARCH SUPPORTS, AND THE VOLUME OF SWELLING AT THE GROUND SURFACE. THE RESULTS OF THE MEASUREMENT SHOWED THAT THE SWELLING OF SERPENTINE WAS CAUSED BY THE EXPANSION AND MOVEMENT OF THE PLASTIC ZONE PRODUCED AROUND THE TUNNEL. MAXIMUM POSSIBLE EARTH PRESSURE AND THE DESIGN EARTH PRESSURE WERE CALCULATED TO FACILITATE THE DESIGNING OF STEEL ARCH SUPPORT AND THE LINING CONCRETE, APPLICABLE TO CERTAIN CASES CHARACTERIZED BY EARTH PRESSURE. THE ACTUALLY MEASURED VALUES OF THE SECTION FORCE PRODUCED IN THE STEEL ARCH SUPPORT AGREED WITH THE CALCULATED VALUES BASED ON THE ELASTICITY THEORY. /AUTHOR/

Spring analog model for flexible culvert behavior

Abstract: AN ANALOG MODEL CONSISTING OF PIN-JOINTED RIGID SEGMENTS IS USED TO SIMULATE THE SOIL-CULVERT INTERACTION OF A FLEXIBLE CIRCULAR CULVERT SUBJECTED TO EARTH LOADING. THE SOIL BEHAVIOR IS EXPRESSED IN TERMS OF THE CONSTRAINED MODULUS, WHICH SOME INVESTIGATORS HAVE INDICATED CAN BE DETERMINED FROM THE DRY DENSITY. THE FORCES DUE TO THE SOIL WEIGHT ARE APPLIED AT THE JOINTS BY MEANS OF CALIBRATED SPRINGS, WHERE THE STIFFNESSES OF THE SPRINGS ARE SET TO CORRESPOND WITH THE STRESS-STRAIN CHARACTERISTICS OF THE SURRONDING SOIL, AND THE EFFECT OF SETTLEMENT OF THE ADJACENT EMBANKMENT IS HANDLED BY MOVING THE SPRING SUPPORTS THROUGH CALCULATED DISTANCES. THE RESULTING RESPONSE OF THE MODEL IS MEASURED, AND THESE DATA, TOGETHER WITH A MODIFICATION FACTOR TO ACCOUNT FOR RING STIFFNESS, ARE SUGGESTED FOR POSSIBLE USE IN DETERMINING DIRECTLY THE RING FORCES AND DEFORMATIONS OF THE CULVERT FOR A WIDE RANGE OF FIELD CONDITIONS. /AUTHOR/