Showing papers on "Lateral earth pressure published in 1972"

Expansion of Cavities in Infinite Soil Mass

Abstract: A GENERAL SOLUTION IS PRESENTED TO THE PROBLEM OF EXPANSION OF SPHERICAL AND CYLINDRICAL CAVITIES IN AN INFINITE SOIL MASS. THE SOIL IS ASSUMED TO BEHAVE AS AN IDEAL ELASTIC-PLASTIC SOLID, FOLLOWING THE COULOMB-MOHR FAILURE CRITERION AND EXHIBITING VOLUME CHANGES IN A PLASTIC REGION SURROUNDING THE CAVITY. BEYOND THE PLASTIC REGION THE SOIL IS ASSUMED TO BEHAVE AS AN ISOTROPIC, LINEARLY DEFORMABLE SOLID. IT IS SHOWN THAT THE PRINCIPAL PARAMETERS AFFECTING THE ULTIMATE CAVITY PRESSURE ARE: THE INITIAL GROUND STRESS, STRENGTH AND VOLUME CHANGE CHARACTERISTICS OF THE SOIL, AND AND THE RIGIDITY INDEX OF THE SOIL (DEFINED AS THE RATIO OF SHEAR MODULUS TO INITIAL SHEAR STRENGTH). NUMERICAL EXAMPLES SHOW THE USE OF THE DERVIED SOLUTIONS FOR COMPUTATION OF ULTIMATE CAVITY PRESSURE, EVALUATION OF PRESSUREMETER TESTS AND COMPUTATION OF POREWATER PRESSURE CAUSED BY PILE DRIVING. /ASCE/

Freezing and heaving of saturated and unsaturated soils

Abstract: ANALYSIS OF THE BEHAVIOR OF AIR--WATER, ICE--WATER, AND AIR--ICE INTERFACES SHOWS THAT THE APPARENT CONTACT ANGLE BETWEEN AN AIR--ICE INTERFACE AND THE WALL OF A SOIL PORE OUGHT TO VARY RAPIDLY WITH CHANGES IN PORE WATER PRESSURE AND ICE PRESSURE. THIS PAPER GIVES THE EXPECTED RELATIONSHIP AND SHOWS THAT COOLING OF FAIRLY DRY SOIL, WITH FREEZING NUCLEATED AT ONE SPOT, SHOULD CAUSE CERTAIN PORES TO FILL ABRUPTLY WITH ICE, THUS DEPLETING THE WATER CONTENT OF THE SURROUNDING SOIL. THIS CONCLUSION AGREES WITH AVAILABLE DATA. IT IS SUGGESTED THAT THE ICE PRESSURE IS SLIGHTLY GREATER THAN ATMOSPHERIC PRESSURE WHEN PORES FILL. LIMITED DATA AVAILABLE IN THE LITERATURE INDICATE THAT A GIVEN MOIST SOIL MAY OR MAY NOT HEAVE; WHEN IT DOES, THE ICE LENSES APPARENTLY FORM SOME DISTANCE BEHIND THE FREEZING FRONT. TO EXPLAIN THIS, THE CONCEPTS OF PRIMARY AND SECONDARY HEAVING ARE PROPOSED FOR SATURATED SOIL. PRIMARY HEAVING OCCURS WHEN THE BASE OF THE GROWING ICE LENS COINCIDES WITH THE LIMIT OF FREEZING, AND THE RATE OF HEAVING IS LIMITED BY THE RATE OF HEAT EXTRACTION. SECONDARY HEAVING IS BELIEVED TO OCCUR WHEN THE FREEZING EXTENDS BELOW THE NOMINAL BASE OF THE (VISIBLE) ICE LENS. ICE IN THE FROZEN PORES CAN MOVE, RELATIVE TO THE PARTICLES, AS AN INTEGRAL PART OF THE GROWING LENS. A SOLUTION MODEL OF SECONDARY HEAVING IS USED TO ILLUSTRATE AN INCREASE OF ICE PRESSURE FROM THE FREEZING FRONT TO THE BASE OF THE ICE LENS, WHICH WILL OCCUR AT A POINT WHERE ICE PRESSURE IS EQUAL TO THE OVERBURDEN PRESSURE. IT IS CONTENTED THAT SECONDARY HEAVING PRODUCES LARGER HEAVING PRESSURES THAN PRIMARY HEAVING AND EXPLAINS WHY PREVIOUS THEORIES UNDERSTIMATED THE MAXIMUM HEAVING PRESSURE OF SATURATED SOIL. IT IS INFERRED THAT WHENEVER HEAVING OCCURS AS THE FREEZING FRONT IS DESCENDING THROUGH THE SOIL, THE PROCESS MUST BE SECONDARY HEAVING. IT IS SUGGESTED THAT THE DEVELOPMENT OF SIGNIFICANT HEAVING PRESSURES BY UNSATURATED SOIL WILL ORDINARILY INVOLVE SECONDARY HEAVING AND THAT THE PRESSURE DEVELOPED IS LESS THAN THAT DEVELOPED BY THE SAME SOIL WHEN IT IS SATURATED. /AUTHOR/

Expansion of Cylindrical Probes in Cohesive Soils

Abstract: The present study shows that the cylindrical expansion tests can not only solve foundation problems by empirical method but are also a means to study the undrained behavior of cohesive soils. On theoretical grounds, it has been shown that the undrained stress-strain curve of the soil can be derived from the pressure meter curve. New testing techniques have been developed, much more sophisticated than the classical ones. The following information has been obtained on a few cohesive soils: horizontal at rest pressure; undrained stress-strain curve of the undisturbed soil for strains up to 5% and in situ undrained cohesion, which appears higher than those determined by classical methods.

State of the art of soft-ground tunneling

Abstract: THE PRESENT TREND IS TOWARD USING SHIELDS THAT HAVE NOT SIGNIFICANTLY IMPROVED IN DESIGN IN RECENT YEARS AND EXCAVATING MACHINES IN WHICH THE GREATEST ADVANCES HAVE BEEN MADE IN MUCKING AND LINING SYSTEMS. ALTHOUGH SAFETY HAS BECOME OF PRIMARY IMPORTANCE, SOME OF THE SKILLS PREVIOUSLY USED IN SOFT-GROUND TUNNELING SUCH AS HAND MINING ARE NOT PRACTICED BY TODAY'S WORKMAN. BASED ON SCHMIDT'S METHOD (1969), THE SHAPE OF THE SETTLEMENT CURVE CAN BE DETERMINED BY PROBABILITY FUNCTIONS IF SUCH PARAMETERS AS THE GROUND SURFACE, TUNNEL DIAMETER, ETC. ARE CONSIDERED. THE SETTLEMENTS ASSOCIATED WITH CONSTRUCTION MAY INVOLVE SOIL MOVEMENT TOWARD THE WORKING FACE AND INTO ANNULAR SPACES SURROUNDING THE TUNNEL LINING THUS RESULTING IN THE REMOVAL OF THE ORIGINAL STRESSES WITHIN THE SOIL MASS. THE DESIGN OF TUNNEL LININGS IS CLASSSIFIED INTO (1) FLEXIBLE LINERS, WHICH INTERACT FULLY WITH THE SOIL, MUST BE DESIGNED TO REGISTER OVERALL STRESS DISTRIBUTIONS, TO WITHSTAND BENDING MOMENTS, AND TO PREVENT BUCKLING; AND (2) RIGID LINERS, IN WHICH THE COEFFICIENT OF EARTH PRESSURE AT REST CAN BE ESTIMATED ALONG WITH THE MOMENTS AND THRUSTS SINCE THE SOIL IS AN ASSUMED LOAD. A GENERAL METHOD FOR DETERMINING THE STIFFNESS OF A TUNNEL LINER SYSTEM THAT INTERACTS WITH THE SOIL IS PROPOSED. IN THIS METHOD OF BURNS AND RICHARDS (1964) AND HOEG (1968), THE COMPRESSIBILITY RATIO IS SEEN AS A PART OF THE EXTENSIONAL STIFFNESS; THE STIFFNESS MEASUREMENT IS OBTAINED BY SUBJECTING A SECTION TO UNIFORM EXTERNAL PRESSURE THUS RESULTING IN NO CHANGE OF SHAPE AND YET DIAMETRIC STRAINS ARE RECORDED BY USING YOUNG'S MODULUS AND POISSON'S RATIO. THE FLEXIBILITY RATIO, BEING THE SECOND PART OF THE ABOVE METHOD, REFLECTS THE RESISTANCE OF THE TUNNEL SECTION AND THE LINEAR TO A CHANGE IN SHAPE UNDER A STATE OF PURE SHEAR. FOR BOTH TYPES OF RATIO, SLIPPAGE BETWEEN THE SOIL INTERFACE, THE STRUCTURAL LINERS, AND THE TUNNEL SECTION MUST BE ACCOUNTED FOR: EQUATIONS FOR SLIPPAGE OF A DEEPLY BURIED TUNNEL ARE GIVEN FOR CROWN AND INVERT AND FOR THE SPRINGLINE. FOR MORE COMPLEX CONDITIONS, SUCH AS TUNNEL LINERS DESIGNED FOR OVERCONSOLIDATED CLAYS INCLUDING HIGH BENDING MOMENTS AND HIGH THRUSTS AT THE CROWN AND INVERT, FINITE-ELEMENT METHODS ARE APPROPRIATE.

In-situ measurement of lateral pressures in clay

Abstract: THIS PAPER DEALS WITH A SIMPLE METHOD OF IN-SITU MEASUREMENT OF THE LATERAL EARTH PRESSURE IN NORMALLY CONSOLIDATED CLAYS. THE METHOD DEVELOPED IS BASED ON THE PRINCIPALS OF HYDRAULIC FRACTURING. A VERTICLE CRACK IS INITIATED IN THE SOIL AROUND A PIEZOMETER TIP. THE WATER PRESSURE AT WHICH THE CRACK CLOSES IS MEASURED, AND THIS PRESSURE IS BELIEVED TO BE IDENTICAL TO THE TOTAL STRESS ACROSS THE CRACK. FROM THIS THE COEFFICIENT OF EARTH PRESSURE AT REST (K SUB 0 VALUE) CAN BE CALCULATED. THE METHOD IS USED K SUB 0 VALUES AT SIX SITES. AT TWO OF THESE THE CLAY IS QUICK, AND AT THE OTHER FOUR NON-QUICK LEAN OR PLASTIC. THE K SUB 0 VALUES ARE FOUND TO BE IN THE RANGE 0.40-0.50 FOR THE QUICK AND 0.50-0.60 FOR THE NON-QUICK CLAYS. BENEATH A FILL AN INCREASE IN THE HORIZONTAL STRESSES IS MEASURED. A COMPARISON OF THE K SUB 0 VALUES OBSERVED IN THE FIELD WITH THOSE MEASURED IN THE LABORATORY INDICATES THAT IN A CLAY DEPOSIT K SUB 0 INCREASES WITH TIME. /AUTHOR/

Lateral pressures on basement wall. results from full-scale tests

Abstract: THE TEST RESULTS INDICATE THAT HIGH LATERAL EARTH PRESSURES CAN DEVELOP DURING THE PLACEMENT OF A GRANULAR BACKFILL BEHIND A BASEMENT WALL. THE RESULTS ALSO SHOW THAT THE EARTH PRESSURE DISTRIBUTION WILL BE APPROXIMATELY LINEAR IF THE SOIL IS PLACED LOOSELY WITHOUT COMPACTION. THE MEASURED LATERAL EARTH PRESSURE CORRESPONDED K = 0.35 FOR A GRAVELLY SAND AND K = 0.31 FOR A SILTY FINE SAND. THE MEASUREMENTS SHOWED THAT A REDISTRIBUTION OF EARTH PRESSURES TOOK PLACE WITH TIME IN THE SILTY FINE SAND, AND THAT THE EARTH PRESSURES INCREASED CONSIDERABLY WHEN THE BACKFILL MATERIAL FROZE. THE LATERAL EARTH PRESSURE WAS APPROXIMATELY RECTANGULARLY DISTRIBUTED IN THE COMPACTED BACKFILL OF GRAVELLY SAND. IN THE COMPACTED SILTY FINE SAND, THE EARTH PRESSURE WAS CONSIDERABLY HIGHER CLOSE TO THE SURFACE OF THE BACKFILL THAN AT THE BOTTOM. THE TOTAL LATERAL PRESSURE FOR THE COMPACTED BACKFILL WAS IN SOME CASES LESS THAN THAT OF THE LOOSELY PLACED MATERIAL. AN EXTERNAL LOAD ACTING ON THE SURFACE OF THE BACKFILL CAUSED A LARGE INCREASE OF THE LATERAL EARTH PRESSURE IN THE LOOSELY PLACED MATERIAL, WHILE THE PRESSURE INCREASE IN THE COMPACTED MATERIAL WAS SMALL. /TRRL/

Soil failure under inclined loads

Abstract: THE MOST COMMON EXAMPLE OF THE APPLICATION OF INCLINED LOADS TO THE SOIL IS THE PLATE-GROUSER THIS CONSISTS OF A STRIP FOOTING WITH A VERTICAL ARM AT ONE END THE MOST USUAL LOADING ARRANGEMENT IS ONE IN WHICH A FIXED VERTICAL LOAD IS APPLIED AND THEN THE HORIZONTAL LOAD IS INCREASED UNTIL FAILURE OCCURS A THEORY HAS BEEN DEVELOPED WHICH WILL PREDICT THE MAXIMUM HORIZONTAL FORCE, ASSUMING THAT THE SOIL IS DENSE ENOUGH TO BE REASONABLY DESCRIBED BY THE COULOMB EQUATION THE THEORY IS BASED ON SLIP LINE FIELDS INCLUDING WEDGES OF SOIL THAT ARE NOT FAILING THESE SLIP LINE FIELDS VARY SYSTEMATICALLY WITH THE INTERFACE ANGLE AND THE ANGLE OF INTERNAL SHEARING RESISTANCE OF THE SOIL AND THEY ARE A FUNCTION OF THE DIRECTION OF MOTION OF THE INTERFACE A COMPUTER PROGRAM IS PROVIDED WHICH WILL SOLVE THE PROBLEM DIRECTLY IF THE DIRECTION OF MOTION IS GIVEN IT WILL ALSO SOLVE THE MORE PRACTICAL SITUATION DESCRIBED ABOVE BY AN ITERATIVE PROCEDURE THE POSTULATED SLIP LINE FIELDS HAVE BEEN SHOWN TO BE CORRECT BY MEANS OF GLASS BOX PHOTOGRAPHS GIVING EXCELLENT AGREEMENT WITH THE THEORY THE PREDICTIONS OF PASSIVE PRESSURE HAVE BEEN VERIFIED BY A SERIES OF FORCE MEASUREMENTS ON QUITE LARGE GROUSERS DRIVEN INTO SATURATED CLAY, DRY SAND AND AN INTERMEDIATE LOAM /AUTHOR/

Earth pressures on flexible structures

Abstract: THE STATE OF KNOWLEDGE REGARDING EARTH PRESSURES ON SHEETPILE WALLS AND EXCAVATION BRACING SYSTEMS IS REVIEWED WITH A VIEW TOWARD DEVELOPING AN IMPROVED UNDERSTANDING OF THE FACTORS GOVERNING THE MAGNITUDES AND DISTRIBUTIONS OF THE EARTH PRESSURES ON FLEXIBLE STRUCTURES. THE BEHAVIOR OF ANCHORED SHEETPILE WALLS IS EXAMINED IN LIGHT OF MODEL TESTS, FIELD OBSERVATIONS, AND THEORETICAL ANALYSES. THESE PROVIDE A CLEAR PICTURE OF THE EFFECTS OF WALL DEFLECTION, ANCHOR YIELD, AND ARCHING. REVIEW OF AVAILABLE FIELD OBSERVATIONS INDICATES THAT THE TOTAL PRESSURES ON EXCAVATION BRACING SYSTEMS GENERALLY IS CONTROLLED BY THE SHEAR STRENGTH OF THE SOIL, WHILE THE DISTRIBUTION OF EARTH PRESSURES IS DETERMINED BY ARCHING. THESE CONSIDERATIONS, TOGETHER WITH RECENT ADVANCES IN MEASURING THE SHEAR STRENGTH OF CLAYS, CAN EXPLAIN THE ANOMALOUSLY HIGH STRUT LOADS IN SOME EXCAVATIONS IN WEAK CLAYS. THE USE OF THE FINITE ELEMENT METHOD IS DISCUSSED AND ILLUSTRATED, BY ANALYSES OF SHEETPILE WALLS AND AN EXCAVATION BRACING SYSTEM. /AUTHOR/

Earth pressure measurement on a braced slurry-trench wall in soft clay

Abstract: EARTH PRESSURE CELLS WERE PLACED ON THE OUTSIDE OF A FOUNDATION WALL, 20 M HIGH AND 1 M THICK, THAT WAS CONSTRUCTED BY THE SLURRY-TRENCH METHOD IN SOFT CLAY. THE MAGNITUDE AND DISTRIBUTION OF TOTAL EARTH PRESSURE ON THE WALL WERE MEASURED BEFORE, DURING, AND AFTER EXCAVATION OF THE SOIL ON ONE SIDE OF THE WALL. DURING EXCAVATION THE WALL WAS SUPPORTED AT THREE LEVELS AND AT THE BOTTOM WHERE IT WAS KEYED INTO THE BEDROCK. THIS ARTICLE SUMMARIZES THE EARTH PRESSURE MEASUREMENTS AS WELL AS RELATED OBSERVATIONS OF GROUND SETTLEMENT, DEFLECTION OF THE WALL, PORE PRESSURE CHANGES AND STRESSES IN THE REINFORCING STEEL IN THE INSTRUMENTED PANEL. /AUTHOR/

Earth pressures on flexible structures (state of the art report)

Abstract: THE STATE OF KNOWLEDGE OF EARTH PRESSURE ON SHEET PILE WALLS AND EXCAVATION BRACING SYSTEMS IS DESCRIBED WITH A VIEW TO DEVELOPING AN IMPROVED UNDERSTANDING OF THE FACTORS GOVERNING THE MAGNITUDE AND DISTRIBUTION OF EARTH PRESSURES ON FLEXIBLE STRUCTURES. THE BEHAVIOR OF ANCHORED SHEET PILE WALLS IS EXAMINED IN THE LIGHT OF MODEL TESTS, FIELD OBSERVATIONS, AND THEORETICAL ANALYSES. THESE PROVIDE A CLEAR PICTURE OF THE EFFECTS OF WALL DEFLECTION, ANCHOR YIELD, AND ARCHING. REVIEW OF AVAILABLE FIELD OBSERVATIONS INDICATES THAT THE TOTAL PRESSURES ON EXCAVATION BRACING SYSTEMS GENERALLY IS CONTROLLED BY THE SHEAR STRENGTH OF THE SOIL, WHILE THE DISTRIBUTION OF EARTH PRESSURES IS DETERMINED BY ARCHING. THESE CONSIDERATIONS, TOGETHER WITH RECENT ADVANCES IN MEASURING THE SHEAR STRENGTH OF CLAYS, CAN EXPLAIN THE ANOMALOUSLY HIGH STRUT LOADS IN SOME EXCAVATIONS IN WEAK CLAYS. THE USE OF THE FINITE ELEMENT METHOD IS DISCUSSED AND ILLUSTRATED BY ANALYSES OF SHEET PILE WALLS AND AN EXCAVATION BRACING SYSTEM. /TRRL/

Lateral earth pressure on a bridge abutment

Abstract: THE LATERAL EARTH PRESSURES ON THE ABUTMENTS OF A 110M LONG REINFORCED CONCRETE FRAME BRIDGE HAVE BEEN MEASURED DURING THE COMPACTION OF THE BACK FILL AS WELL AS AFTER THE COMPLETION OF THE BRIDGE. THE BACK FILL CONSISTED OF SANDY GRAVEL AND MEDIUM SAND, WHICH WAS COMPACTED IN LAYERS BY A 3.0 TON VIBRATORY ROLLER AND BY A 140KG VIBRATORY PLATE COMPACTOR. MODERATELY HIGH EARTH PRESSURES WERE MEASURED DURING THE COMPACTION OF THE BACK FILL MATERIAL, WHICH INCREASED APPROXIMATELY LINEARLY WITH DEPTH. THE LATERAL EARTH PRESSURES VARIED APPRECIABLY DURING THE YEAR AS THE BRIDGE EXPANDED AND CONTRACTED DUE TO TEMPERATURE VARIATIONS AND SHRINKAGE. THE HIGHEST EARTH PRESSURES WERE MEASURED DURING THE SUMMERS WHEN THEY WERE APPROXIMATELY EQUAL TO THOSE IMMEDIATELY AFTER COMPACTION OF THE BACK FILL. THE LOWEST EARTH PRESSURES WERE MEASURED DURING THE WINTER WHEN THE BRIDGE CONTRACTED. LARGE DAILY VARIATIONS OF THE LATERAL EARTH PRESSURES CAUSED BY EXPANSION AND CONTRACTION OF THE BRIDGE WERE ALSO OBSERVED. /TRRL/

Influence of wall stiffness and anchor prestressing on earth pressure distribution

Abstract: EXAMPLES OF A TIRED-BACK RETAINING WALL IN SAND JUST TOUCHING THE BEDROCK ARE PRESENTED. A 'FLEXIBLE' SHEET PILE- WALL AND A 'STIFF' CAST-IN-SITU DIAPHRAGM ARE CONSIDERED IN A FINITE-ELEMENT-ANALYSIS PERMITTING THE CALCULATION OF STRESS REDISTRIBUTION AFTER LOCAL FAILURE. THE RESULTS SHOW THE IMPORTANT INFLUENCE OF THE WALL FLEXIBILITY ON THE EARTH PRESSURE DISTRIBUTION, NOTABLY ON THE MOBILIZATION OF EARTH RESISTANCE AND THE END- RESTRAINT-EFFECT AT THE TOP. THE ANCHOR PRESTRESSING FORCE IS SEEN TO INFLUENCE VERY EFFECTIVELY THE GROUND AND WALL MOVEMENTS AND CONSEQUENTLY THE DANGER OF DAMAGES AT ADJACENT STRUCTURES. IT IS SHOWN THAT THE INCREASE OF THE ANCHOR FORCE WITH PROCEEDING EXCAVATION DIMINISHES RAPIDLY AT HIGHER PRESTRESSING LEVELS. /TRRL/

Scale-dependent plasticity analysis for sand

Abstract: NUMERICAL PROCEDURES FOR TWO DIMENSIONAL PLASTICITY ANALYSIS OF ZONAL FAILURE IN SAND HAVE BEEN MODIFIED TO INCLUDE THE CURVATURE OF THE MOHR-COULOMB ENVELOPE WITH PRESSURE. THE PROCEDURES ARE APPLIED TO PASSIVE RETAINING WALLS, SURFACE FOOTINGS AND DEEP STRIP FOOTINGS. THEY SHOW HOW THE ANGLE OF SHEARING RESISTANCE VARIES IN INDIVIDUAL FAILURE ZONES AND HOW ITS DISTRIBUTION CHANGES WITH SIZE OF STRUCTURE. IT IS CONCLUDED THAT FAILURE LOAD PARAMETERS SHOULD BE DIRECTLY RELATED TO STRUCTURE SIZE AND INITIAL SAND DENSITY.

Lateral Pressures from Soft Clay

Abstract: FOLLOWING CESSATION OF RETAINING WALL MOVEMENT EARTH PRESSURES FROM SOFT CLAY HAVING LIQUIDITY INDICES EQUAL TO OR GREATER THAN UNITY CREEP BACK TO THE AT-REST VALUE. THE RIGID MODEL RETAINING WALL TESTS INDICATE THAT REDUCTIONS IN THE LATERAL PRESSURE OCCUR IMMEDIATELY WHEN WALL MOVEMENTS ARE INDUCED. THE CONVENTIONAL ACTIVE PRESSURE DISTRIBUTION IS PRODUCED WHEN THE WALL IS SUBJECTED TO A HORIZONTAL DISPLACEMENT OF APPROXIMATELY 5% OF THE WALL HEIGHT. IMMEDIATELY AFTER THE WALL MOVEMENTS ARE TERMINATED THE LATERAL PRESSURE INCREASES, WITH THE LONG TERM PRESSURE EQUALLING THE LATERAL PRESSURE ACTING BEFORE WALL MOVEMENT WAS INITIATED. THIS LONG TERM PRESSURE CAN BE CALCULATED BY MEANS OF AN EXPRESSION WHICH IS SIMILAR TO THE CONVENTIONAL LONG TERM ACTIVE PRESSURE EXPRESSION, BUT WITH THE RELAXED SHEAR STRENGTH BEING CONSIDERED AS THE MOBILIZED SHEAR STRESS IN THE BACKFILL. THE RELAXED SHEAR STRENGTH MAY BE MEASURED IN TORSION SHEAR TESTS. ALTERNATIVELY THE LONG TERM PRESSURE MAY BE CALCULATED FROM VALUES OF THE REST COEFFICIENT WHICH CAN BE MEASURED THROUGH TESTS IN A SPECIAL TRIAXIAL CELL. /ASCE/

Lower and upper bounds for stability of earth-retaining structures

Abstract: TWO COLLAPSE THEOREMS OF PLASTICITY THEORY ARE APPLIED TO THE PLANE STRAIN CASE OF EARTH-RETAINING STRUCTURES. INTERNAL KINEMATIC CONDITIONS (FLOW RULES) ARE TAKEN INTO ACCOUNT. THE THEOREMS ARE FORMULATED FOR PURELY COHESIVE AND PURELY FRICTIONAL DILATING SOILS. FOR GETTING LOWER LIMITS USE IS MADE OF RECTILINEAR STRESS DISCONTINUITIES. FOR UPPER LIMITS, FAILURE MECHANISMS CONSISTING OF VELOCITY DISCONTINUITIES ARE PROPOSED. THE NECESSITY OF MORE REFINED FAILURE MECHANISMS THAN THE USUAL SLIP CIRCLE IS PROVED BY THE EXAMPLE OF AN ANCHORED BULKHEAD IN PURELY COHESIVE SOILS. FOR DILATING FRICTIONAL SOILS THE ADMISSIBLE SLIP LINES ARE STRAIGHT LINES OR SPIRALS. THE FRICTIONAL RESISTANCE DEPENDS ON THE ANGLE OF FRICTION AND THE ANGLE OF DILATANCY. THE INFLUENCE OF EXTERNAL AND INTERNAL KINEMATIC CONDITIONS IS SHOWN IN THREE SIMPLE EXAMPLES OF EARTH PRESSURE. FINALLY, TYPICAL FAILURE MECHANISMS FOR RETAINING WALLS WITH COHESIONLESS BACKFILL ARE PRESENTED. /TRRL/

Earth pressure on retaining walls

Abstract: 1. The earth pressure diagrams observed in the field on retaining walls and on the walls of lock chambers with discontinuous bottom slabs may be obtained by adding the basic pressure and the backfill pressure. 2. A method for determining the backfill pressure is presented in this article, as applied to the model of a foundation of finite thickness by considering the variable modulus of deformation of the backfill, corresponding to the different depths, which permits obtaining design earth pressures close to those observed in the field. 3. The analysis of the walls of lock chambers and of retaining walls with the inclusion of the backfill pressure makes it possible to design adequately the elements of these structures and to avoid possible failures.

Braced cuts in sand and clay

Abstract: The excavation and bracing of cuts with depth of less than 20 feet merely require close adhesion to existing empirical rules. The earth pressure against the bracing of such cuts is a factor of secondary importance, because it is more economical to use one of the standard systems of bracing at the price of some excess material than to adapt the bracing to local soil conditions. On the other hand, the bracing of deep and wide cuts accounts for a considerable part of the total cost. Furthermore, substantial savings can often be realized by various departures from the standard methods of bracing, such as providing for a large unobstructed working space between the bottom of the cut and the lowest row of struts. In order to comply with the requirements of both safety and economy, it is necessary to make a thorough soil survey and to prepare the plans on the basis of the results of earth-pressure computations. Experience has shown that the magnitude of the total earth pressure against the bracing of cuts in sands and soft to medium saturated clays can be computed reliably on the basis of earth-pressure theories, providing the cut is not underlain by a deep deposit of clay with a metastable structure in which the maximum shear strength is exceeded as a result of the excavating operations. On the other hand, the distribution of load among struts arranged vertically cannot be predicted by earth-pressure theory. The loads for which the struts should be designed may be computed by the methods described under the preceding subheading. The application of theory or of similar procedures to the design of bracing systems for cuts in other types of soil should be carried out with caution until the reliability of the results is demonstrated by field measurements.

Earth pressures at a junction between an embankment dam and a concrete dam

Abstract: IN COMPOSITE DAMS, CONSISTING PARTLY OF EMBANKMENT AND PARTLY OF CONCRETE, IT IS NECESSARY TO FORM JUNCTIONS BETWEEN THE TWO TYPES OF SECTIONS. IF THE RISK OF CRACKING OF THE EMBANKMENT CORE AT THE JUNCTION IS TO BE AVOIDED, THE CORE MUST EXERT A MINIMUM EARTH PRESSURE ON THE CONCRETE WHICH IS RELATED TO THE RESERVOIR PRESSURE AT THE COW GREEN DAM. A JUNCTION WAS FORMED PARTLY BY BUTTING THE CORE AGAINST THE END FACE OF THE CONCRETE GRAVITY SECTION AND PARTLY BY THE CORE OVERLAPPING THE UPSTREAM FACE OF THE CONCRETE. THE CORE-CONCRETE INTERFACES WERE INSTRUMENTED WITH EARTH PRESSURE CELLS AND PIEZOMETERS AND IT WAS FOUND THAT THE EARTH PRESSURE ON THE END FACE WAS EQUAL TO 73% OF THE VERTICAL WEIGHT OF SOIL, WHEREAS ON THE UPSTREAM FACE IT WAS ONLY EQUAL TO 30%. /TRRL/

Behavior of anchored sheet-pile wall exposed to frost action

Abstract: A SHEET-PILE WALL WAS BUILT IN THE AUTUMN OF 1968. DURING THE WINTER OF 1968/69 SOME OF THE ANCHOR TIE-RODS FAILED DUE TO FROST ACTION. AFTER TEMPORARY STRUTTING, NEW RODS WERE INSTALLED. THE NUMBER OF RODS WAS ALSO INCREASED. DURING THE SUMMER OF 1969, VERTICAL SAND DRAINS EQUIPPED WITH ELECTRICAL CABLES FOR HEATING WERE INSTALLED. THE BEHAVIOR OF THE WALL HAS CONTINUOUSLY BEEN FOLLOWED SINCE NOVEMBER 1969. DURING THE WINTER OF 1969/70 VERY HIGH STRESSES WERE MEASURED, AND HEATING WAS FOUND NECESSARY TO REDUCE THE STRESSES. DURING THE SUMMER OF 1970 THE STRESSES AND STRAINS WERE NORMAL. HOWEVER, THE STRESS IN THE RODS INCREASED AGAIN DURING THE WINTER OF 1970/71, BUT NO HEATING WAS NECESSARY. IT WAS CONCLUDED THAT LATERAL EARTH PRESSURE DOES NOT AGREE WITH THE RANKINE THEORY IN THE BEGINNING BUT MAY DO SO WITH TIME. FROST ACTION INCREASES THE PRESSURE CONSIDERABLY, BUT CAN IN A FAIRLY SHORT TIME BE REDUCED BY HEATING, WHICH CAN BE DONE INTERMITTENTLY. /TRRL/

The influence of model retaining wall displacement on active and passive earth pressures in sand

Abstract: THE PAPER PRESENTS DATA ON THE EXPERIMENTAL INVESTIGATION INTO THE INFLUENCE OF THE DIFFERENT KINDS OF MOVEMENT AND DEFORMATION OF A SEMI-FLEXIBLE MODEL RETAINING WALL ON THE VALUES AND THE DISTRIBUTION OF LATERAL ACTIVE AND PASSIVE PRESSURES EXERTED AGAINST THE WALL BY DRY SAND BACKFILL WITH AN UNLOADED AND LOADED HORIZONTAL SURFACE. THE INFLUENCE OF THE FLEXIBILITY OF THE WALL, STRESS-STRAIN HISTORY, KINEMATICAL CONDITIONS, WALL FRICTION, VOLUME CHANGES PRODUCED BY SHEAR, TIME AND BOUNDARY RESTRAINING EFFECT ON THE VALUES AND THE DISTRIBUTION OF SAND PRESSURES ARE STATED. /TRRL/

Total pressure measurements

Abstract: THE AUTHORS RECALL THAT TOTAL PRESSURE CELLS OF THE GLOZL TYPE ARE EXTENSIVELY USED IN INVESTIGATIONS INTO THE BEHAVIOUR OF SOIL UNDER FOUNDATIONS (FOOTINGS, PILES, EMBANKMENTS ON COMPRESSIBLE SOIL) AND GIVE THE PRINCIPLE ON WHICH THE CELL IS BASED (FLEXIBLE MEMBRANE PLACED IN A PLANE ENCLOSED SPACE FILLED WITH OIL; PRESSURE IS APPLIED ON THAT SPACE AND THE OIL IS PUMPED OUTSIDE UNTIL THE MEMBRANE IS LOOSENED). THE DISADVANTAGES OF THESE CELLS, IN PARTICULAR THEIR LACK OF SENSITIVITY, ARE MENTIONED. THESE DISADVANTAGES LED TO A MODIFICATION OF THE MEASUREMENT METHOD. DETAILS ARE GIVEN OF THE PNEUMATIC EQUIPMENT USED FOR STATIC MEASUREMENTS IN WHICH AN OPENING IS KEPT PERMANENTLY OPENED DURING MEASUREMENT. IN THE HYDRAULIC EQUIPMENT USED FOR STATIC AND DYNAMIC MEASUREMENTS, CONSTANT FLOW IS MAINTAINED IN THE CIRCUITS BY MEANS OF AN INCOMPRESSIBLE FLUID. EXAMPLES ARE GIVEN OF MEASUREMENTS CARRIED OUT WITH THE HYDRAULIC EQUIPMENT (PILE UNDER HORIZONTAL STRESS, PLATE BEARING TESTS).

Pressure at rest of cohesive soils

Abstract: USING JAKY'S EQUATION FOR THE DETERMINATION OF THE PRESSURE OF LOOSE SOILS AT REST WHEN ONLY PART OF THE SHEARING STRENGTH IS MOBILIZED, THIS STATE OF STRESS FOR THE ANGLE OF STATIC FRICTION WAS DERIVED. TO DETERMINE THE PRESSURE AT REST OF COHESIVE SOILS THE ANGLE OF STATIC FRICTION AND COHESION AT REST ARE USED TO DERIVE, BY MEANS OF MOHR'S CIRCLE, ONE EQUATION FOR DETERMINATION OF THE PRESSURE OF COHESIVE SOIL AT REST. THE AUTHOR'S THEORY IS COMPARED WITH THE MEASURED PRESSURES OF SOILS AT REST AND IN THE CASE OF CLAY, THESE PRESSURES ARE LOW, DUE TO COHESIVENESS, THAN THOSE CALCULATED ACCORDING TO JAKY. /TRRL/

Earth pressure measurements

Abstract: RESULTS OF EARTH PRESSURE MODEL TESTS ARE PRESENTED. THE TESTS WERE MADE WITH ARTIFICIAL EMERY, USING A BOX WITH OVERALL DIMENSIONS 2.1, 5.1, 2M. THE BACK WALL OF THE BOX COULD BE ROTATED AROUND ANY HORIZONTAL AXIS IN THE PLANE OF THE WALL. PASSIVE EARTH PRESSURE VALUES ARE GIVEN FOR THREE KINDS OF ROTATION; THE GENERAL PICTURE FOR ANY POSITION OF THE AXIS OF ROTATION COULD ALSO BE GIVEN. MODEL TESTS WITH THE CANTILEVER TYPE OF ROTATING WALLS REVEALED THE EFFECT OF THE SHAPE OF THE WALL. /TRRL/

Lateral forces on an experimental section of the madrid subway

Abstract: IN A SECTION OF THE NEW URBAN UNDERGROUND RAILWAY IN MADRID, MEASURING DEVICES HAVE BEEN MOUNTED IN THE CONCRETE TUNNEL LINING TO MEASURE ACTUAL STRESSES WITHIN THE CONCRETE AND DIRECT EARTH PRESSURES AGAINST THE LINING, USING VENTILGEBER INSTRUMENTS. THE STRESS DISTRIBUTION IN THE CONCRETE VAULT PROVED TO BE EXACTLY THE OPPOSITE OF WHAT WAS EXPECTED. THERE WAS A HIGH COMPRESSION IN THE INTRADOS AT THE CROWN AND HAUNCHES. THE POSSIBLE CAUSES OF THIS PHENOMENON WERE STUDIED, AND IT WAS CONCLUDED THAT THIS IS PROBABLY DUE TO THE LATERAL PRESSURES ORIGINATED BY THE EXPANSIVE CHARACTERISTICS OF THE CLAYS AND TO THE RESIDUAL HORIZONTAL STRESSES THAT MAY EXIST IN THE GROUND, CAUSED BY THE OROGENIC MOVEMENTS OF THE SIERRA DEL GUADARRAMA MOUNTAINS WHICH HAVE PRODUCED NUMEROUS FAULTS IN THE SOIL. A STUDY IS ALSO MADE OF THE ADEQUATE DIMENSIONS AND LAY OUT OF THE PRESSURE BLOCKS FOR A DIRECT MEASUREMENT OF LATERAL EARTH PRESSURES AGAINST THE WALLS. /TRRL/

Limit analysis solutions of earth pressure problems, May 1972 73-64

Abstract: The upper bound technique of limit analysis is used to obtain the active and passive limit earth pressures for a cohesionless soil retained by a rigid wall of varying roughness. The soil is treated as a perfectly plastic medium obeying the Mohr-Coulomb yield criterion and its associated flow rule. Various assumed failure mechanisms are evaluated. The resulting solutions are found to favorably agree with known solutions including those obtained by

The method of associated fields of stress and velocity and its application to earth pressure problems

Abstract: THIS PAPER DESCRIBES A FINITE DIFFERENCE METHOD OF DETERMINING THE NATURE OF THE STRESS AND STRAIN OF A SOIL MASS UNDER PLANE STRAIN CONDITIONS. THE METHOD APPLIES THE THEORY OF CHARACTERISTICS TO BOTH THE STRESS AND VELOCITY FIELDS THROUGH THE LAWS OF STRESS-STRAIN BEHAVIOR OF THE SOIL. THE EVOLUTION IN THESE FIELDS IN ACCORDANCE WITH THE VARIATION IN BOUNDARY CONDITION AND THE STRESS EQUILIBRIUM AND KINEMATIC COMPATIBILITY, IS STUDIED. AN EXAMPLE IS GIVEN OF THE APPLICATION OF THE METHOD TO THE CASE OF A RETAINING WALL ROTATING ABOUT ITS BASE INTO A SAND MASS, UNDER PASSIVE CONDITIONS. /TRRL/

Pressure-time relationship in laterally stressed frozen granular soils.

Abstract: A FROZEN SAND--ICE LAYER, WHEN SUBJECTED TO LATERAL PRESSURE AT A CONSTANT TEMPERATURE SHOWS REDUCTION IN STRESS WITH TIME. INVESTIGATIONS WERE CARRIED OUT TO STUDY THE GENERAL TENDENCY OF THIS REDUCTION IN LATERAL STRESS AND ALSO TO INVESTIGATE THE EFFECTS OF CERTAIN PARAMETERS INFLUENCING THIS BEHAVIOR. TWO DIFFERENT TYPES OF SAND WERE USED TO PREPARE THE SAND--ICE SPECIMENS WITH A VAREITY OF INITIAL POROSITY AND DEGREE OF ICE SATURATION. THEY WERE TESTED AT VARIOUS CONSTANT TEMPERATURE UNDER SELECTED INITIAL PRESSURES. THE MAGNITUDE OF PRESSURE RETAINED BY A FROZEN SAND SAMPLE AT ANY TIME, AFTER COMMENCEMENT OF THE EXPERIMENT, WAS MEASURED BY MEANS OF A PRESSURE GAUGE ATTACHED TO THE "PRESSURE UNIT." THE REDUCTION IN LATERAL STRESS, EXPRESSED AS A PERCENTAGE OF INITIAL PRESSURE APPLIED TO A FROZEN SAND LAYER, WAS STUDIED AS A FUNCTION OF FIVE VARIABLES: INITIAL PRESSURE, THE INITIAL POROSITY OF THE SAND, THE DEGREE OF ICE SATURATION, TEMPERATURE OF SAMPLE, AND TIME ELAPSED AFTER THE APPLICATION OF INITIAL PRESSURE. EXPERIMENTAL RESULTS WERE PLOTTED IN THE FORM OF PRESSURE--TIME CURVES TO STUDY THE TIME-DEPENDENT BEHAVIOR OF THE SAND--ICE SYSTEM UNDER APPLIED LOAD. ALSO, REDUCTION IN STRESS WAS PLOTTED AGAINST EACH OF THE PREVIOUSLY MENTIONED VARIABLES TO SHOW THEIR INFLUENCE ON THE REDUCTION IN LATERAL STRESS. A GENERAL EQUATION TO PREDICT THE VALUE OF LATERAL PRESSURE RETAINED BY THE SAND--ICE LAYER AT ANY TIME AFTER THE APPLICATION OF A KNOWN INITIAL PRESSURE WAS DERIVED EMPIRICALLY IN TERMS OF THE FIVE VARIABLES.