A New Ring Shear Apparatus and Its Application to the Measurement of Residual Strength

Abstract

Synopsis This Paper describes both the design and principles of operation of a new ring shear apparatus, and its application to the measurement of the residual strength of undisturbed and remoulded samples. As the test results differ significantly from those obtained in multiple reversal direct shear box tests, a critical examination is made of all possible sources of error in both measurement and interpretation. The results of tests on five soils, blue London Clay, brown London Clay, Weald Clay, a Norwegian clay and the Cucaracha Shale from Panama, are presented and discussed in relation to other published residual strength data from tests on these materials. The factors controlling the brittleness of soils tested under drained conditions are examined. Cet article décrit à la fois la conception et les principes d'opération d'un nouvel appareil de mesure du cisaillement circulaire par torsion, et de son application à la mesure des résistances résiduelles d'échantillons non pertubés et remoulés. Comme les résultats des essais diffèrent d'une manière significative de ceux obtenus lors d'essais multiples effectés dans une boîte de cisaillement renversé direct, on donne une analyse critique de toutes les sources d'erreurs possibles à la fois dans les mesures et dans leur interprétation. Les résultats d'essais sur cina sols: arsdle bleu de Londres, argile brun de Londrks, argile de Weald, argile Norvégien et schiste Cucaracha de Panama, sont présentés et discutés par rapport aux autres résultats d'essais de résistance résiduelle publiés sur ces matériaux. On examine les facteurs qui contrôlent la fragilité de ces sols dans des conditions de drainage.

On the Particle Size Distribution of a Basaltic Till

“…Isotropic compression tests were conducted in a high pressure triaxial apparatus and in a rock permeameter, and one-dimensional compression tests were carried out using an oedometer cell that had been modiˆed to enable pressures up to 17 MPa to be applied. Because the eŠec-tive stresses in situ are low, it is likely that the particle size distribution of the sediment results mostly from shearing processes, and therefore shearing tests were performed in the triaxial apparatus as well as in a Bishop-type ring shear apparatus to reach very high strains more typical of the in-situ strains (Bishop et al, 1971). The results obtained from the triaxial tests are described and analysed in more details in Altuhaˆet al (2010).…”

“…The cell pressure was monitored in two ways: by a pressure gauge and by an inline transducer, which logged the data to the computer. (iv) Ring shear apparatus A Bishop-type ring shear apparatus (Bishop et al, 1971) was used to study the crushability of the Langj äokull glacial sediment deformed to high strain levels. The specimens, about 22 mm in thickness and a mean radius of about 62 mm, were sheared by rotating the platen in contact with the base of the specimen at a controlled rate with a variable-speed electric motor and gear boxes while keeping the upper platenˆxed.…”

Seismic Risk Evaluation of Irrigation Tanks: A Case Study in Ibigawa-Cho, Gifu Prefecture, Japan

“…This allows for the full orientation of the clay particles parallel to the direction of shear and the development of a true residual strength condition [3]. To determine the shear strength parameters (residual frictional angle ∅ , cohesion in a residual strength situation, peak frictional angle ∅ and cohesion under a peak strength situation), among the multiplicity of ring shear apparatuses reported by scientists [4], [5], the Bromhead ring shear apparatus developed by Bromhead is becoming widely used due to its simplicity in operation, its reasonable cost and its availability compared to previous models. Stark and Eid [6] also showed that the drained residual strength values measured with the Bromhead apparatus are in excellent agreement with the back-calculated values for landslides at Warden Point in the United Kingdom and at a site in Southern California.…”

State-of-the-art report: GCL shear strength and its measurement – ten-year update

“…The measurement of residual shear strength is unaffected by non-uniform displacement across the specimen. For data reduction purposes, shear displacement is taken at the average radius of the specimen and the average shear stress is calculated from specimen geometry and the applied moment (Bishop et al 1971;Bromhead 1979). Values of peak strength measured from ring shear tests are usually in agreement with those measured from direct shear tests if the diameter ratio exceeds 0.7 (Stark and Poeppel 1995).…”