Suction Measurements on a Saskatchewan Soil Using a Direct-Measurement, High-Range Suction Sensor

1997 ◽  
Vol 1596 (1) ◽  
pp. 84-92
Author(s):  
Delwyn G. Fredlund ◽  
Julian K-M. Gan ◽  
Yun Guan ◽  
Neil Richardson
Keyword(s):  
Tensile Strength ◽  
Direct Measurement ◽  
Negative Pressure ◽  
Laboratory Data ◽  
Matric Suction ◽  
Bridge Site ◽  
Cavitation Nuclei ◽  
The Town ◽  
High Range

A tensiometric-type suction sensor capable of direct measurement of matric suctions greater than 100 kPa has recently been developed. The sensor has been used to measure matric suctions up to 1250 kPa. The sensor makes use of the tensile strength of water for the measurement of matric suction. The cavitation of water in conventional tensiometers occurs at a negative pressure approaching 1 atmosphere because of the presence of cavitation nuclei. In the absence of cavitation nuclei, the tensile strength of water can be on the order of several atmospheres. The direct-measurement, high-range suction sensor has been used for the measurement of matric suction on borehole samples obtained during a soils investigation at a bridge site near the town of Outlook, Saskatchewan, Canada. The method has proven to be fast and simple to use. Matric suction measurements of the samples from the Outlook bridge site are presented, along with an interpretation of the laboratory data.

Calibration of tensiometer for direct measurement of matric suction

Géotechnique ◽  
2003 ◽  
Vol 53 (1) ◽  
pp. 137-141 ◽  
Author(s):  
A. Tarantino ◽  
L. Mongiovì
Keyword(s):  
Direct Measurement ◽  
Matric Suction

Failure Analysis on the Collapsed Tubing of High Pressure and High Production Gas Well in the Process of Testing and Production

2014 ◽  
Vol 1035 ◽  
pp. 198-203 ◽  
Author(s):  
Ji Jun Xue ◽  
Bin Zhao ◽  
He Zhao
Keyword(s):  
High Pressure ◽  
Tensile Strength ◽  
Multiphase Flow ◽  
Failure Analysis ◽  
Chemical Property ◽  
Negative Pressure ◽  
Gas Well ◽  
Test Study ◽  
High Production ◽  
Macroscopic Analysis

The split, fall, collapse and severe diapirism of tube body happened on one of the tubing used in the gas well of high pressure and high production in the process of the trial extraction. This paper aims to explore the reason of its occurrence through the research of the macroscopic analysis, mechanical and chemical property test and microscopic metallographic test study. The result of the research shows that the multiphase flow of gas, liquid and solid in the tubing may produced an instantaneous negative pressure and increased the possibility of the tubing being collapsed in the process of gas testing and production.Then it resulted in clogging, severe ablation, thinning wall and piercing in tube and finally the tube broke because of the low tensile strength.

Model for predicting tensile strength of unsaturated cohesionless soils

2018 ◽  
Vol 55 (9) ◽  
pp. 1313-1333 ◽  
Author(s):  
Penghai Yin ◽  
Sai K. Vanapalli
Keyword(s):  
Tensile Strength ◽  
Characteristic Curve ◽  
Experimental Studies ◽  
Friction Angle ◽  
Matric Suction ◽  
Degree Of Saturation ◽  
Engineering Practice ◽  
Cohesionless Soils ◽  
Proposed Model ◽  
Earth Structures

The influence of tensile strength on the behaviour of cohesionless soils is typically ignored in geotechnical engineering practice. However, the tensile cracking and subsequent failure characteristics of earth structures, such as dams, slopes and embankments, are significantly influenced by the tensile strength. For this reason, a semi-empirical model is proposed for predicting the variation of the tensile strength of unsaturated cohesionless soils with the degree of saturation, using the soil-water characteristic curve (SWCC) as a tool. The proposed model is capable of predicting the tensile strength arising from matric suction and surface tension, which are related to saturated pores and to the air–water interface associated with water bridges around interparticle contacts in unsaturated pores, respectively. Information about (i) the matric suction (ua– uw), the capillary degree of saturation (Sc), and the residual degree of saturation (Sr) derived from the SWCC; (ii) the mean particle size (d50) and the coefficient of uniformity (Cu) from the grain-size distribution curve; (iii) the void ratio (e); and (iv) the friction angle ([Formula: see text]) at low normal stress level is required to employ this model. The proposed model is validated by comparing the prediction results with measured tensile strength of 10 different unsaturated cohesionless soils (including five sandy soils and five silty soils). The proposed model is promising for use in engineering practice applications as it only requires conventional soil properties, alleviating the need for cumbersome experimental studies for the determination of tensile strength of unsaturated cohesionless soils.

scholarly journals NEGATIVE PRESSURE GENERATED BY OCTOPUS SUCKERS: A STUDY OF THE TENSILE STRENGTH OF WATER IN NATURE

1991 ◽  
Vol 157 (1) ◽  
pp. 257-271 ◽  
Author(s):  
ANDREW M. SMITH
Keyword(s):  
Tensile Strength ◽  
Hydrostatic Pressure ◽  
Negative Pressure ◽  
Pressure Transducer ◽  
Sea Water ◽  
Pure Water ◽  
Cavitation Threshold ◽  
Negative Pressures ◽  
The Difference

The decrease in hydrostatic pressure generated by octopus suckers adhering to wettable and non-wettable surfaces was measured using a flush-mounted miniature pressure transducer. The cavitation thresholds, or lowest sustainable pressures, of sea water on the same surfaces were also measured and were compared with the pressures generated by octopuses. It is shown that suckers can generate hydrostatic pressures below OMPa on moderately wettable surfaces. This disprovesthe commonly repeated assumption that suckers cannot produce pressures below a vacuum and suggests that the importance of suction in attachment mechanisms may have been overlooked. On epoxy, the lowest recorded pressure was −0.168MPa (0.268MPa or 2.66atm below ambient), and the octopus generated negative pressure in 35% of the pulls that were considered maximal efforts. The suckers never generated negative pressures on non-wettable surfaces. These results are in agreement with the range of pressures that sea water can sustain on the same surfaces. It is suggested, therefore, that cavitation, the failure of water in tension, limits the attachment force of suckers. The difference between the cavitation threshold of water in nature and the cavitation threshold of pure water is discussed.

The nature of the mechanical impedance to seedlings by soil surface seals

Soil Research ◽  
1965 ◽  
Vol 3 (1) ◽  
pp. 45 ◽  
Author(s):  
W Arndt
Keyword(s):  
Tensile Strength ◽  
Soil Properties ◽  
Direct Measurement ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Mechanical Impedance ◽  
Modulus Of Rupture ◽  
Single Index ◽  
Soil Cohesion ◽  
Structural Parts

The nature of seedling emergence through soil surface seals under a variety of field and model situations is described. In this process the importance of the shear and compressive strengths of the seal has been demonstrated. Resistance to emergence has been shown to be also due to gravity, soil cohesion, and friction between structural parts. The mechanics of seedling emergence is too variable and complex to be expressed by a single index, such as the tensile strength of free samples, as in the modulus of rupture determinations of Richards (1953). Direct measurement of mechanical impedance is preferable to refining the use of such indices, and provides a basis for a better understanding of the relation between seedlings and soil properties influencing emergence.

scholarly journals Cavitation inception from bubble nuclei

2015 ◽  
Vol 5 (5) ◽  
pp. 20150006 ◽  
Author(s):  
K. A. Mørch
Keyword(s):  
Tensile Strength ◽  
Tap Water ◽  
Time History ◽  
Experimental Investigations ◽  
Cavitation Inception ◽  
Pressure Time ◽  
History Of ◽  
Cavitation Nuclei ◽  
Pressure Changes ◽  
Surrounding Liquid

The tensile strength of ordinary water such as tap water or seawater is typically well below 1 bar. It is governed by cavitation nuclei in the water, not by the tensile strength of the water itself, which is extremely high. Different models of the nuclei have been suggested over the years, and experimental investigations of bubbles and cavitation inception have been presented. These results suggest that cavitation nuclei in equilibrium are gaseous voids in the water, stabilized by a skin which allows diffusion balance between gas inside the void and gas in solution in the surrounding liquid. The cavitation nuclei may be free gas bubbles in the bulk of water, or interfacial gaseous voids located on the surface of particles in the water, or on bounding walls. The tensile strength of these nuclei depends not only on the water quality but also on the pressure–time history of the water. A recent model and associated experiments throw new light on the effects of transient pressures on the tensile strength of water, which may be notably reduced or increased by such pressure changes.

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