Showing papers in "Canadian Geotechnical Journal in 1972"

Coupled Horizontal and Rocking. Vibration of Embedded Footings

Abstract: The prediction of the coupled response to horizontal forces is of major importance for the design of footings exposed to dynamic effects. The theory of surface footings greatly overestimates the re...

An Engineering Theory of Creep of Frozen Soils

Abstract: Most of the existing theories of creep have been developed from two different viewpoints: micromechanistic and macroanalytical. The former deal with events occurring at the atomic level and provide...

Down-drag on piles in clay due to negative skin friction

Abstract: In Part I of this report the results are given from 43 months of measurements of forces and bending moments on two instrumented precast piles driven through 40 m (130 ft) of soft clay and 15 m (50

The Bearing Capacity of Rigid Piles Under Inclined Loads in Sand. I: Vertical Piles

Abstract: The bearing capacity of rigid vertical and batter piles under inclined loads in sand has been determined for model piles of different depth/diameter ratios. The first part of this paper deals with ...

Limitations of the Driving Formulas for Predicting the Bearing Capacities of Piles in Sand

Abstract: It has often been shown by previous investigators that the existing pile driving formulas yield bearing capacities which usually do not stand in good correlation to the actual bearing capacities of...

In-situ Determination of Undrained Stress-strain Behavior of Sensitive Clays with the Pressuremeter

Abstract: A theory originally proposed by Gibson and Anderson (1961) has been extended to enable a direct determination of the whole undrained stress-strain curve of the clay from the pressure-expansion curve obtained in a conventional pressuremeter test.When applied to some pressuremeter tests carried out in Leda clay in the Ottawa area, the method enabled us to determine the undrained stress-strain behavior of the clay up to axial strains of about 20%. It is thought that, when properly performed, the test is able to furnish the data on the undrained stress-strain and strength properties of sensitive clays comparable to the laboratory test results obtained on block samples. Its particular feature is that it also furnishes a true picture of the post-peak strength decrease in terms of shear strain which is usually difficult to obtain by any other type of test.

Strength Anisotropy and Time Effects of Two Sensitive Clays

Abstract: A COMPREHENSIVE EXPERIMENTAL INVESTIGATION WAS PERFORMED ON BLOCK SAMPLES OF TWO SENSITIVE CLAYS TAKEN FROM THE SITES TO RECENT SLIDES IN QUEBEC. BOTH ISOTROPICALLY CONSOLIDATED DRAINED AND UNDRAINED TRIAXIAL TESTS WERE CARRIED OUT ON SPECIMENS TRIMMED AT VARIOUS ANGLES FROM THE VERTICAL DIRECTION. DIRECT AND INDIRECT DRAINED TENSION TESTS WERE ALSO PERFORMED SO AS TO COVER THE ENTIRE STRESS RANGE FROM TENSILE TO COMPRESSIVE STRESSES BEYOND THE PRECONSOLIDATION PRESSURE. RESULTS OF THIS STUDY SHOWED THAT THE EFFECTIVE STRESS STRENGTH ENVELOPES ARE PRONOUNCEDLY NON-LINEAR AND STRONGLY ANISTROPIC IN THE WORKING STRESS RANGE USUALLY ENCOUNTERED. THE RATIO OF MINIMUM STRENGTH TO STRENGTH OF VERTICAL SAMPLES VARIES FROM 0.54 TO 0.70. THE DRAINED TENSILE STRENGTH IS ALSO ANISTROPIC, THE VALUE OBTAINED FOR FRACTURE ACROSS STRATIFICATION IS ABOUT THREE TIMES THAT ALONG STRATIFICATION. THE TIME TO FAILURE HAS AN IMPORTANT EFFECT ON THE PEAK STRENGTH. THE POST-PEAK BEHAVIOR WAS STUDIED AND IT IS SHOWN THAT THE STRENGTH AT LARGE STRAINS MAY BE DEDUCED FROM RESULTS OF CIU AND CID TESTS. THE MODULUS OF DEFORMATION VARIES WITH CONSOLIDATION PRESSURE IN A MANNER SIMILAR TO THAT OF THE PEAK STRENGTH ENVELOPE. IT IS ESSENTIALLY ISOTROPIC, BUT DECREASES WITH STRAIN RATE. FINALLY, APPLICATION OF THESE RESULTS TO SLOPE STABILITY PROBLEMS IS DISCUSSED.

A Study of Anchorages for Transmission Tower Foundations

Abstract: A number of uplift tests have been conducted on anchors proposed for use to support high voltage transmission line towers both for the conventional four legged structure and for the guyed-type stru...

Downdrag Measurements on a 160-Ft Floating Pipe Test Pile in Marine Clay

Abstract: Large negative skin friction loads were observed on a 160 ft (49 m) steel pipe test pile floating in marine clay. The test pile was driven, open-ended, on the centerline of a 30 ft (9 m) high granular approach fill on the Quebec Autoroute near Berthierville. Since the installation was made in 1966 the fill has settled 21 in. (53 cm), dragging the pile down with it. Negative skin friction acting along the upper surface of the pile was resisted by positive skin friction acting along the lower end as it penetrated the underlying clay. Under these conditions the pile compressed about (2 cm). Analysis of the axial strains indicated that a peak compressive load of 140 t developed at the inflection point between negative and positive skin friction 73 ft (22 m) below the top of the pile. Negative and positive skin friction acting on the upper surface of the pile exceeded the in situ shear strength and approached the drained strength of the soil where excess pore water pressures had dissipated. At the lower end wh...

Design and Performance of an Expressway Constructed Over Peat by Preloading

Abstract: This paper presents the complete record of the laboratory investigations and field observations made in conjunction with the construction of expressway embankments built by preloading over a muskeg...

Surface Settlement of a Deep Elastic Stratum Whose Modulus Increases Linearly with Depth

Abstract: An examination has been made of the behavior of a half space of elastic material of constant Poisson's ratio, whose Young's modulus increases linearly with depth, and which is subject to a strip or...

An Approach to the Problem of Progressive Failure

Abstract: In this paper, the different factors that contribute to progressive failure are briefly reviewed, and the necessary conditions for its occurrence delineated.Experiments on specimens trimmed from block samples of several clays were performed to study the post-peak stress deformation behavior. It is shown that the stiffness of the testing system has an important influence on the post-peak characteristics. A method of obtaining the effective 'residual' angle of friction from drained triaxial tests is developed.Because of the localization of deformation in the failure zone, both in the laboratory and in the field, the laboratory nominal post-peak stress–strain relationship cannot be directly applied to field problems. Based on laboratory and field observations on the mechanism of deformation, the ratio of the shear modulus of the failure zone to that of the pre-peak range is proposed as a deformation parameter to be used in analysis of progressive failure.A simplified theory for the solution of the problem of...

A Simple Ko Triaxial Cell

Abstract: The need to reproduce the same stress path in the laboratory as in the field is emphasized, especially for initial consolidation, which in most cases is under Ko conditions. A simplified Ko triaxia...

The Behavior of Piles Driven in Clay. I. An Investigation of Soil Stress and Pore Water Pressure as Related to Soil Properties

Abstract: THIS PAPER OUTLINES RESEARCH ON LARGE MODEL PILES AND SOME FULL-SCALE PILES DRIVEN INTO INSENSITIVE CLAY TO STUDY THE PHENOMENA OF LOAD TRANSFER AND THE EFFECT OF PILE DRIVING ON THE SOIL. IT IS DIVIDED INTO TWO PARTS. PART I DEALS WITH THE STRESS FIELD SET UP BY DRIVING A LARGE MODEL PILE INTO AN INSTRUMENTED CLAY BED AND THE STRESSES MEASURED FOR SOME FULL-SCALE TIMBER PILES. PART II PRESENTS AN EVALUATION OF THE LOAD CARRYING CAPACITY OF THE MODEL PILE AND COMPARES THE RESULTS WITH FULL-SCALE PILE LOAD TESTS. THE SOIL PROPERTIES ARE EVALUATED IN TERMS OF EFFECTIVE STRESS FOR AN ESTIMATE OF THE BEARING CAPACITY OF THE PILES. THE MEASURED SOIL DISPLACEMENTS NEAR THE SHAFT AND BASE AGREE WELL WITH PLASTIC THEORY, WHILE THE OBSERVED MAGNITUDE OF THE PORE PRESSURES IN THE CLAY DUE TO DRIVING ARE SMALLER AND THE RATE PORE PRESSURE DISSIPATION IS GREATER THAN EXPECTED THEORETICALLY. THE MAGNITUDE OF THE TOTAL AND EFFECTIVE RADIAL STRESSES SURROUNDING THE PILE IS MAINLY RELATED TO THE STRESS CHANGES IN THE SOIL DUE TO PLACING THE PILE, AND SUBSEQUENT STRESS CHANGES ARE RELATIVELY SMALL. ON THE OPTHER HAND, THE TANGENTIAL AND VERTICAL STRESSES VARY APPRECIABLY WITH TIME AND THE LATTER STRESSES DEPART CONSIDERABLY FROM ESTIMATES BASED ON ELASTIC THEORY, DUE TO LOCK-IN-SOIL STRESSES. AN APPROXIMATE THEORY IS PRESENTED TO ESTIMATE THE AVERAGE EFFECTIVE RADIAL STRESS ON THE PILE SHAFT IN CONNECTION WITH THE ULTIMATE SHAFT CAPACITY. THIS PROPOSED APPROACH IS SUPPORTED BY OBSERVATIONS IN SOME CLAYS OF LOW SENSITIVITY, BUT REQUIRES FURTHER RESEARCH IN OTHER TYPE OF CLAYS.

Field Tests of Grouted Rod Anchors in Permafrost

Abstract: The use of guyed towers for power transmission and communication systems in northern Canada has received increased attention in recent years. In many cases perennially frozen ground (permafrost) poses special problems. The resistance of frozen soil to uplift forces must be evaluated for the design of anchors of guyed structures built on permafrost. There is little experience or information available, however, concerning the behavior of frozen soil in response to uplift forces or the capacity of various types of anchors. A field study of anchors in permafrost was therefore undertaken by the Division of Building Research of the National Research counci l of Canada to evaluate, in particular, the displacements associated with long-term creep of frozen soil under load. initial appraisal of various kinds of anchors suggested that grouted rod anchors were a type that should be investigated. Early in 1967 a total of 18 such anchors (nine at each site) were installed in permafrost at Thompson and Gillam, Manitoba. This paper describes the installation and testing procedures and the results of the test programs conducted on the anchors at both sites. In the analysis of the results the creep behavior of grouted anchors is related to U basic creep parameters of frozen soil, taking into account the effects of temperature and normal pressure. The theory employed allows field creep data to be used for estimating the long-term adfreeze strength of frozen soil, information that is required in the design

Deformation Characteristics of Granular Materials Under Hydrostatic Compression

Abstract: The deformation characteristics of sand and other granular materials under hydrostatic compression are studied in the conventional triaxial apparatus using 4 × 4 in. (10 × 10 cm) specimens. Modifications have been made for measuring small axial strains and free end platens were used. The errors in testing have been estimated and their effect was evaluated. Different kinds of granular materials were tested to study the effect of the physical properties of the material on its deformational behavior.The results showed that the total deformation of a mass of sand subjected to a hydrostatic compression is generally not recoverable, and can be divided into elastic (recoverable) and sliding (irrecoverable) components. It has also been found out that for a dense specimen of sand most of the total deformation is recoverable, since the sliding component of deformation represents only a small fraction of the total deformation. The results also showed that for the very dense specimen axial and radial strains were nea...

Effects of Pile Driving in Clays

Abstract: This study summarizes the information given in the literature as well as observations made by the author. The effects of driving piles on remolding, stresses, and properties of the clay are conside...

In-situ determination of undrained stress-strain behavior of sensitive clays with the pressure meter

Abstract: A THEORY ORIGINALLY PROPOSED BY GIBSON AND ANDERSON (1961) HAS BEEN EXTENDED TO ENABLE A DIRECT DETERMINATION OF THE WHOLE UNDRAINED STRESS-STRAIN CURVE OF THE CLAY FROM THE PRESSURE-EXPANSION CURVE OBTAINED IN A CONVENTIONAL PRESSUREMETER TEST. WHEN APPLIED TO SOME PRESSUREMETER TESTS CARRIED OUT IN LEDA CLAY IN THE OTTAWA AREA, THE METHOD ENABLED US TO DETERMINE THE UNDRAINED STRESS-STRAIN BEHAVIOR OF THE CLAY UP TO AXIAL STRAINS OF ABOUT 20%. IT IS THOUGHT THAT, WHEN PROPERLY PERFORMED, THE TEST IS ABLE TO FURNISH THE DATA ON THE UNDRAINED STRESS-STRAIN AND STRENGTH PROPERTIES OF SENSITIVE CLAYS COMPARABLE TO THE LABORATORY TEST RESULTS OBTAINED ON BLOCK SAMPLES. ITS PARTICULAR FEATURE IS THAT IT ALSO FURNISHES A TRUE PICTURE OF THE POST-PEAK STRENGTH DECREASE IN TERMS OF SHEAR STRAIN WHICH IS USUALLY DIFFICULT TO OBTAIN BY ANY OTHER TYPE OF TEST.

Clay Layer Fabric and Oedometer Consolidation of a Soft Varved Clay

Abstract: The oedometer consolidation properties of the clay layers of varved sediments from New Liskeard, Ontario have been presented and interpreted with reference to current ideas on soil fabric, bonding, and environment of deposition. The sensitive, brittle nature of the clays is expressed by Cc values as high as 1.35 and "S" shaped consolidation curves. Preconsolidation above any previous possible overburden pressure is explained by bonding of a net random, flocculated fabric as measured by X-ray diffraction methods. Rates of secondary consolidation up to 4.5%/log cycle at loads close to the preconsolidation pressure reflect structural breakdown of the soil fabric within a very critical range of stress and strain.The flocculated soil structure at New Liskeard is compared with the more parallel fabric of the compositionally similar stratified glacial clays at Welland, Ontario. It is suggested that both deposits developed flocculated soil structures during deposition but that the Welland clays were deposited and...

On the causes of natural cementation in sensitive soils

Abstract: A unique characteristic of many naturally cemented sensitive soils is that they are made up of finely ground fresh rock debris, "rock flour", much of which is very susceptable to chemical weatherin...

A thermal analysis for structures on permafrost

Abstract: A REVIEW OF THE COMPLEXITIES IN THE SOLUTION OF THERMAL PROBLEMS ON FREEZING AND THAWING SOILS IS PRESENTED. THE DIFFERENTIAL EQUATIONS GOVERNING THE CONDUCTION OF HEAT, IN WHICH LATENT HEAT IS CONSIDERED AS A HEAT SOURCE, ARE STATED. AN EQUIVALENT CONVOLUTION VARIATIONAL THEOREM IS USED TO CONSTRUCT A TWO-DIMENSIONAL FINITE ELEMENT MODEL WITH LINEAR VARIATION OF TEMPERATURE WITHIN THE ELEMENT. TWO TIME STEP IDEALIZATIONS OF THE EQUATIONS ARE DESCRIBED, AND ALTERNATIVE FORMS OF THE LATENT HEAT MATRIX ARE DERIVED. SOME RESULTS OBTAINED WITH THE SIMPLEST LATENT HEAT MATRIX ARE PRESENTED TO ILLUSTRATE THE VERSATILITY OF THE TECHNIQUE. /RATAOC/

Field loading tests on muskeg

Abstract: RESULTS OF TESTS PERFORMED USING A 1.8-M (6-FT) DIAMETER FLEXIBLE BASED TANK CAPABLE OF BEING FILLED WITH 3.6-M (12-FT) OF WATER ARE PRESENTED. TWO SERIES OF TESTS WERE PERFORMED ON A MUSKEG WITH AN UNDRAINED SHEAR STRENGTH OF 5-7.5 KN/SQ. M (100-150 LB/SQ.FT). THE FIRST CONSISTED OF FILLING THE TANK ALONE AND THE SECOND WITH THE TANK POSITIONED AT THE CENTER OF A 4.5-M (15-FT) DIAMETER 0.6-M (2-FT) HIGH FLEXIBLE BASED RESERVOIR. THE RESULTS THUS SIMULATE THE COMPARISON OF THE EFFECT OF BERMS ON THE STABILITY OF EMBANKMENTS. CONSIDERATION IS GIVEN TO THE SHORT TERM EFFECT OF BERMS WHERE THEY ARE CONSTRUCTED RAPIDLY AT THE SAME TIME AS THE CENTRAL FILL AND THE LONG TERM EFFECT WHERE THEY AND THE CENTRAL FILL ARE CONSTRUCTED SLOWLY. THE RESULTING VERTICAL MOVEMENTS WERE MEASURED USING A TORPEDO SETTLEMENT GAUGE. THE HORIZONTAL MOVEMENTS WERE MEASURED USING AN INCLINOMETER AS WELL AS A HORIZONTAL MOVEMENT DEVICE. THE PORE PRESSURES WERE MEASURED USING FINE STONED PIEZOMETERS. IN ADDITION SUITABLE LABORATORY TESTS WERE CONDUCTED TO COMPARE PREDICTED AND MEASURED RESULTS.

Analytical Study of a Braced Excavation in Weak Clay

Abstract: Analysis of the problem of braced excavations is complicated by the large number of variables involved and by the complex interaction and behavior of the soil and the supporting materials. For this...

Passive Pressure Coefficients for Sand

Abstract: Values of Kp for a horizontal bed of sand acting against a vertical wall have been computed using Terzaghi's logarithmic spiral method. The results compare favorably with other theories.

The Performance of Tied-Back Sheet Piling in Clay

Abstract: In Ottawa in 1969 a tied-back sheet pile wall was installed to provide temporary support in one side of a 12 m deep excavation through Champlain Sea deposits to shale bedrock. The wall was designed...

Design of Deep Socketed Caissons Into Shale Bedrock

Abstract: Deep sockets into bedrock are often used to achieve large capacities for caissons. Most of the available design methods are mainly empirical with little or no relationship to the in situ quality of rock. Bearing pressures and socket skin friction values adopted seem to be conservative in the absence of reliable field information. This paper deals with the problems associated with the design of deep socketed caissons.A concise review of the regional case histories and available design methods involving deep sockets into bedrock are presented. Various methods of testing rock in the laboratory and in the field for obtaining the desired design parameters are discussed. The application of laboratory and field test results in design are given. Problems associated with the construction and inspection of the caissons are summarized.

Stabilite des culees de ponts etablies sur des pieux traversant une couche molle.

Abstract: ON A ANALYSE LE COMPORTEMENT DE 15 PONTS POUR LESQUELS DES MOUVEMENTS HORIZONTAUX DES CULEES ONT ETE OBSERVES LES CULEES SONT ETABLIES SUR PIEUX, LES PIEUX TRAVERSENT UNE COUCHE MOLLE, ILS ONT ETE MIS EN PLACE AVANT DE CONSTRUIRE LES REMBLAIS OU DES LEUR CONSTRUCTION EN TENANT COMPTE DES CARACTERISTIQUES DES PIEUX, DE LA COMPRESSIBILITE ET LA GEOMETRIE DE LA COUCHE MOLLE, ON DONNE LES CONDITIONS POUR LESQUELLES L'OCCURRENCE DE TELS MOUVEMENTS EST TRES PROBABLE DANS LE CAS DE CULEES ETABLIES A MI-NIVEAU DES REMBLAIS, SUR DES PIEUX D'ACIER, UNE BORNE SUPERIEURE AUX MOUVEMENTS HORIZONTAUX EST PROPOSEE PLUSIEURS SOLUTIONS SONT SUGGEREES AFIN D'EVITER LE COUVEMENT DES CULEES

Microstructure of a Laboratory Sedimented Flocculated Illitic Sediment

Abstract: Scanning electron microscope study of the fabric of air dried laboratory sedimented flocculated illite reveals a network of randomly oriented flakes or groups of flakes. The author hopes the results will provide a useful point of reference in considering fabric changes induced in consolidated clays.

Some Observations at le Coteau Landslide, Gatineau, Quebec

Abstract: In April 1971, landslide activity developed in a 100-ft (30.5-m) high clay slope in a housing development. This note describes the landslide and discusses the pore-water pressure measurements made at the site.