Showing papers in "Geotechnique in 1951"

The Ultimate Bearing Capacity of Foudations

Abstract: Synopsis In the first part of the article a theory of bearing capacity is developed, on the basis of plastic theory, by extending the previous analysis for surface footings to shallow and deep foundations in a uniform cohesive material with fntemal friction. The theoretical results are represented by bearing capacity factors in terms of the mechanical properties of the soil, and the physical characteristics of the foundation. The base resistance of foundations in purely cohesive material is found to increase only slightly with foundation depth; for deep foundations the skin friction is, therefore, large compared with the base resistance. In cohesionless material, however, the base resistance increases rapidly with foundation depth and depends to a considerable extent on the earth pressure coefficient on the shaft; for deep foundations the base resistance is the predominant feature and the shin friction is relatively small. In the second part of the article the main results of laboratory and field loading ...

Effect of Rate of Loading on the Strength of Clays and Shales at Constant Water Content

Abstract: Synopsis Investigations performed at Harvard University during the past three years show that some types of brittle undisturbed clays and clay shales creep under a sustained load, and that they ultimately fail under a sustained load appreciably less than the strength indicated by a normal laboratory compression test. The shear strengths of six such soils were found to be reduced to 40–80 per cent. of their normal values in thirty days. This may explain some slides which have developed on slopes that stood for many years without noticeable movement. In contrast, it was found that two laboratory compacted soils, and one undisturbed soil which was not fully saturated, tended to become stronger and stiffer under sustained loads, even though water content was kept constant. These results may prove of value in connexion with the design of embankments. Des recherches effectuees a 1'Universite de Harvard, au cours de ces trois dernieres annees, montrent que quelques types d'argiles et de schistes argileux friable...

Testing The Shear Strength of Clay in Sweden

Abstract: Synopsis In this Paper an account is given of some apparatuses for testing shear strength which have previously been described only in Swedish. The routine methods used in Sweden for testing shear strength are also outlined, and their dependability is discussed. Finally, the reliability of the triaxial test is considered. Dans cette etude on rend compte de quelques appareils pour essayer la resistance au cisaillement qui n'ont ete decrits prealablement qu'en suedois. On indique aussi les methodes de routine utilisees en Suede pour essayer la resistance au cisaillement, et la croyabilite de ces methodes est soumise a discussion. Enfin, on examine la veracite de l'essai triaxial.

Computation of Load Stresses in a Three-Layer Elastic System

Abstract: Synopsis In a recent Paper two methods were used to determine the stresses in a two-layer road system, caused by the application of uniform load over a circular area on the top surface. By the first method, due to Burmister, formulae were obtained, and evaluated by numerical quadrature, for the stresses on the axis of the applied load, while the relaxation method of Southwell was used to compute the off-axial stresses. Here Burmister's method is applied to the three-layer case, and results are given for a wide range of the parameters involved. The variables are the radius of the loaded area, the thicknesses of the two top layers, and the elasticities of the three layers, equivalent to four independent parameters. Formulae are given for the horizontal and vertical stress components, and the results are presented in tabular form. No use is made of relaxation, since the labour of producing results of the required accuracy is prohibitive. Dans une recente etude on avait employe deux methodes pour determiner l...

Investigation and Measurements of the Shear Strengths of Saturated Cohesive Soils

Abstract: Synopsis Methods for the determination of the shear strength of cohesive soil have been in process of development since 1935 in the Laboratory for Soil Mechanics at the Federal Institute of Technology in Zurich, and the combined use of the ring shear apparatus and the triaxial apparatus has been specially studied. Through a division of the shear strength in friction and cohesion, and based on tensile tests and cone tests with artificially consolidated samples, it is proved that the cohesive part increases linearly with the pressure. For conditions without stressed pore water the relationship between shear strength and consolidation pressure (a-line) is set up in parallel to the relationship between shear strength and water content. The special conditions which must be observed during shear tests with relieved samples are dictated by the change in volume which takes place during the test. As a complement to the shear strength the residual shear stress is introduced. Through a number of tests. the theoretic...

Fundamental Considerations On The Shear Strength Of Soil

Abstract: Synopsis In this Paper attention is drawn to the importance of the water content in relatidn to the shear strength of saturated clay. Following Hvorslev, the shear strength is divided into a true cohesion, which is merely a function of the water content at the point considered, and an internal friction, determined by the effective normal stress on the plane under consideration. It is suggested in the shear-strength diagram (Fig. 1) that the cohesion be plotted as a function of the equivalent consolidation pressure; a curve then appears which indirectly establishes the relationship between cohesion and water content. For normally consolidated saturated clay it can be stated that an interdependence exists between water content and effective major principal stress— that is, the water content depends solely on the magnitude of the effective major principal stress and, conversely, if the external stresses are changed under undrained conditions, the effective major principal stress remains unaltered at the valu...

Les Mesures De Cisaillement Dans Les Laboratoires Français

Abstract: Synopsis Dans cet expose, l'auteur rappelle rapidement les methodes de mesure du cisaillement appliquees dans les laboratoires francais. I1 passe ensuite a la description des essais faits a I'occas...