scholarly journals Coefficient of Earth Pressure at Rest in Granular Material with Consideration of Stress History

1976 ◽  
Vol 25 (274) ◽  
pp. 627-631
Author(s):  
Kazuya YASUHARA
Keyword(s):  
Granular Material ◽  
Earth Pressure ◽  
Stress History

The effect of the earth pressure coefficients on the runout of granular material

2007 ◽  
Vol 22 (10) ◽  
pp. 1437-1454 ◽  
Author(s):  
Marina Pirulli ◽  
Marie-Odile Bristeau ◽  
Anne Mangeney ◽  
Claudio Scavia
Keyword(s):  
Granular Material ◽  
Earth Pressure ◽  
Pressure Coefficients ◽  
The Earth

scholarly journals The pressure exerted by granular material: an application of the principles of dilatancy

1931 ◽  
Vol 131 (816) ◽  
pp. 53-89 ◽  
Keyword(s):  
Granular Material ◽  
Coefficient Of Friction ◽  
Flat Surface ◽  
Small Difference ◽  
Fundamental Property ◽  
Earth Pressure ◽  
Essential Factor ◽  
Friction Couple ◽  
Simple Experiment ◽  
The Coefficient Of Friction

The author had spent about three years endeavouring unsuccessfully to obtain experimental confirmation of the recognised theories of earth pressure and was attempting to measure the “ coefficient of friction ” of sand (on which all the theories are based) when a research student engaged on this work, Mr. C. P. R. de Villiers, called his attention to a remarkable phenomenon. This was recognised as an example of Dilatancy as described by Osborne Reynolds, and quickly led to the recognition of dilatancy as the fundamental property of granular material on which its behaviour and the forces it exerts ultimately depend. Two well known methods were being used to measure the coefficient of friction; the apparatus is shown in figs. 1 and 2. The outer vessels contained sand and the couples to rotate the disc (fig. 1) and the cylinder (fig. 2) were measured. With neither apparatus could repeat results be obtained. The impossibility of getting repeat results had been the fundamental trouble in all our work. But while making these tests Mr. de Villiers observed that the surface of the sand heaved up at the instant when rotation of the disc or cylinder began. This was particularly surprising in the disc apparatus (fig. 1) in which the moving disc was about 6 inches below the surface of the sand. To check whether the sand was really expanding, as it appeared to be, a simple experiment was made with the cylindrical apparatus (fig. 2). The cylinder was completely filled with sand while it was gently tapped ; no ramming was applied and the hole in the top through which it was filled was left open. When an attempt was made to rotate the inner cylinder it was found to be locked, and when the cylinder was finally forced round the couple required was 270 times the ordinary friction couple. When the sand was emptied out a lot of fine dust was found with it showing that rotation had not occurred until the sand was crushed. These experiments showed that the closeness of packing of the grains of sand was an essential factor in determining its behaviour and furnished the key to the irregular results of all our previous experiments. Small changes in packing may produce large effects. To illustrate the magnitude of the effect of closeness of packing a simple experiment on foundation pressures may be quoted. A small flat plate was laid on the flat surface of sand in a large box, and the force was measured to cause the plate to sink into the sand. When the sand was loosely poured into the box and trickled off level the force was only about one-tenth of that required when the sand was shaken and rammed to get it into the close-packed con­dition. (The densities of the sand in the two conditions were about 91 and 110 lb. per cubic foot; this small difference offers no explanation of the large difference in bearing pressure.)

Earth Pressures at Rest Related to Stress History

1965 ◽  
Vol 2 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Elmer W Brooker ◽  
Herbert O Ireland
Keyword(s):  
Axial Stress ◽  
Earth Pressure ◽  
Lateral Strain ◽  
Cohesive Soils ◽  
Stress History ◽  
Chicago Clay ◽  
Liquidity Index ◽  
Shearing Resistance ◽  
History Of ◽  
London Clay

The influence of stress history on the coefficient of earth pressure at rest of remoulded cohesive soils was studied experimentally. A one-dimensional compression test cell and auxiliary controls which enabled the measurement of radial stresses under a condition of zero lateral strain was developed for this purpose. Radial pressures were measured throughout all stages of consolidation up to a maximum axial stress of 2,200 psi and subsequent rebound to zero stresses.Five cohesive soils, the properties of which are well documented, were selected for this study. These soils were: Chicago Clay, Goose Lake Flour, Weald Clay, London Clay, and Bearpaw Shale. 'The selected soils range in plasticity from low to high and cover a range of drained angles of shearing resistance from 15.5 degrees to 27.5 degrees. For testing purposes all soils were remoulded at a liquidity index of 0.5.For a pre-consolidation load of 2,200 psi and various values of the over-consolidation ratio, it was found that the coefficient of earth pressure at rest is related to both the drained angle of shearing resistance and the plasticity index. The coefficient of earth pressure at rest during rebound was found to be a function of the stress history of the soil as defined by the pre-consolidation load and over-consolidation ratio.

Ultra-Rapid Freezing of Isolated Skeletal Muscle Fibers

1977 ◽  
Vol 35 ◽  
pp. 576-577
Author(s):  
Joachim R. Sommer ◽  
Nancy R. Wallace
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Granular Material ◽  
Nuclear Envelope ◽  
Intracellular Calcium ◽  
Ruthenium Red ◽  
Threshold Concentration ◽  
Rapid Freezing ◽  
Frog Skeletal Muscle ◽  
Electrical Isolation

After Howell (1) had shown that ruthenium red treatment of fixed frog skeletal muscle caused collapse of the intermediate cisternae of the sarcoplasmic reticulum (SR), forming a pentalaminate structure by obi iterating the SR lumen, we demonstrated that the phenomenon involves the entire SR including the nuclear envelope and that it also occurs after treatment with other cations, including calcium (2,3,4).From these observations we have formulated a hypothesis which states that intracellular calcium taken up by the SR at the end of contraction causes the M rete to collapse at a certain threshold concentration as the first step in a subsequent centrifugal zippering of the free SR toward the junctional SR (JSR). This would cause a) bulk transport of SR contents, such as calcium and granular material (4) into the JSR and, b) electrical isolation of the free SR from the JSR.

Effect of Some Metabolic Inhibitors on Vinblastine-Induced Ribosomal-Granular Material Complexes

1971 ◽  
Vol 29 ◽  
pp. 548-549
Author(s):  
Awtar Krishan ◽  
Dora Hsu
Keyword(s):  
Granular Material ◽  
Rna Synthesis ◽  
Culture Medium ◽  
Actinomycin D ◽  
Metabolic Inhibitors ◽  
Protein And Rna Synthesis ◽  
Apparent Reduction ◽  
Plant Alkaloids ◽  
In Cells

Cells exposed to antitumor plant alkaloids, vinblastine and vincristine sulfate have large proteinacious crystals and complexes of ribosomes, helical polyribosomes and electron-dense granular material (ribosomal complexes) in their cytoplasm, Binding of H3-colchicine by the in vivo crystals shows that they contain microtubular proteins. Association of ribosomal complexes with the crystals suggests that these structures may be interrelated.In the present study cultured human leukemic lymphoblasts (CCRF-CEM), were incubated with protein and RNA-synthesis inhibitors, p. fluorophenylalanine, puromycin, cycloheximide or actinomycin-D before the addition of crystal-inducing doses of vinblastine to the culture medium. None of these compounds could completely prevent the formation of the ribosomal complexes or the crystals. However, in cells pre-incubated with puromycin, cycloheximide, or actinomycin-D, a reduction in the number and size of the ribosomal complexes was seen. Large helical polyribosomes were absent in the ribosomal complexes of cells treated with puromycin, while in cells exposed to cycloheximide, there was an apparent reduction in the number of ribosomes associated with the ribosomal complexes (Fig. 2).

Stress fields in granular material and implications for performance of robot locomotion over granular media

2015 ◽  
Vol 8 (1) ◽  
pp. 2005-2009
Author(s):  
Diandong Ren ◽  
Lance M. Leslie ◽  
Congbin Fu
Keyword(s):  
Mechanical Properties ◽  
Granular Material ◽  
Granular Media ◽  
Rotation Frequency ◽  
Legged Locomotion ◽  
Working Environment ◽  
Navier Stokes ◽  
Maximum Speed ◽  
Sigmoid Curve ◽  
Multi Body

 Legged locomotion of robots has advantages in reducing payload in contexts such as travel over deserts or in planet surfaces. A recent study (Li et al. 2013) partially addresses this issue by examining legged locomotion over granular media (GM). However, they miss one extremely significant fact. When the robot’s wheels (legs) run over GM, the granules are set into motion. Hence, unlike the study of Li et al. (2013), the viscosity of the GM must be included to simulate the kinematic energy loss in striking and passing through the GM. Here the locomotion in their experiments is re-examined using an advanced Navier-Stokes framework with a parameterized granular viscosity. It is found that the performance efficiency of a robot, measured by the maximum speed attainable, follows a six-parameter sigmoid curve when plotted against rotating frequency. A correct scaling for the turning point of the sigmoid curve involves the footprint size, rotation frequency and weight of the robot. Our proposed granular response to a load, or the ‘influencing domain’ concept points out that there is no hydrostatic balance within granular material. The balance is a synergic action of multi-body solids. A solid (of whatever density) may stay in equilibrium at an arbitrary depth inside the GM. It is shown that there exists only a minimum set-in depth and there is no maximum or optimal depth. The set-in depth of a moving robot is a combination of its weight, footprint, thrusting/stroking frequency, surface property of the legs against GM with which it has direct contact, and internal mechanical properties of the GM. If the vehicle’s working environment is known, the wheel-granular interaction and the granular mechanical properties can be grouped together. The unitless combination of the other three can form invariants to scale the performance of various designs of wheels/legs. Wider wheel/leg widths increase the maximum achievable speed if all other parameters are unchanged.

Sign in / Sign up

Export Citation Format

Share Document