Deformation and strength properties of some rocks in southern Ontario

1979 ◽  
Vol 16 (1) ◽  
pp. 108-120 ◽  
Author(s):  
K. Y. Lo ◽  
M. Hori

Uniaxial compression tests were performed on sedimentary rocks of five different geological formations at various sites in southern Ontario. The deformation behaviour is analysed in terms of the cross-anisotropic elastic theory and typical sets of five independent parameters for each rock unit have been obtained. It is shown that some of the rock types are significantly anisotropic both in deformation and strength behaviour. The practical relevance of the results in the analysis and design of underground structures in these rocks is discussed.

2021 ◽  
Vol 11 (23) ◽  
pp. 11506
Author(s):  
Parvesh Kumar ◽  
Amit Kumar Shrivastava

This paper presents a new testing method for the problems encountered in field testing. To this end, single-tunnel and twin-tunnel small-scale rock models are prepared in the laboratory. A new methodology is proposed to encounter problems that are faced during field testing. The test results show that rock strength characteristics, overburden pressure, and tunnel spacing have important effects on the stability of underground structures. For rocks with poor strength properties, the damage degree is greater. When the strength property of rock changes, the deformation value of unlined tunnels changes from 21.05% to 27.58%, while that of lined tunnels changes from 11% to 21.42%. Also, in the twin tunnel, the deformation value reduces from 20% to 15.78% when the spacing between the tunnels is increased. For the measurement of stress and deformation in tunnels, the results obtained from experiments are analyzed. The method adopted in this study helps determine the tunnel’s design parameters to make it safe under overlying static loads. Finally, the key factors affecting the stability of underground structures are determined by simulating the field conditions through experimental research.


2014 ◽  
Vol 566 ◽  
pp. 158-163 ◽  
Author(s):  
A. Yosimoto ◽  
Hidetoshi Kobayashi ◽  
Keitaro Horikawa ◽  
Keiko Watanabe ◽  
Kinya Ogawa

In order to clarify the effect of strain rate and test temperature on the compressive strength and energy absorption of polyimide foam, a series of compression tests for the polyimide foam with two different densities were carried out. By using three testing devices, i.e. universal testing machine, dropping weight machine and sprit Hopkinson pressure bar apparatus, we performed a series of compression tests at various strain rates (10-3~103s-1) and at several test temperatures in the range of room temperature to 280 ̊C. At over 100 s-1, the remarkable increase of flow stress was observed. The negative temperature dependence of strength was also observed.


2019 ◽  
Vol 38 (2019) ◽  
pp. 168-177 ◽  
Author(s):  
Liu Shi-feng ◽  
Shi Jia-min ◽  
Yang Xiao-kang ◽  
Cai Jun ◽  
Wang Qing-juan

AbstractIn this study, the high-temperature deformation behaviour of a TC17 titanium alloy was investigated by isothermal hot compression tests in a wide range of temperatures (973–1223 K) and strain rates (0.001–10 s−1). Then, the constitutive equations of different phase regimes (α + β and single β phases) were developed on the basis of experimental stress-strain data. The influence of the strain has been incorporated in the constitutive equation by considering its effect on different material constants for the TC17 titanium alloy. Furthermore, the predictability of the developed constitutive equation was verified by the correlation coefficient and average absolute relative error. The results indicated that the obtained constitutive equations could predict the high-temperature flow stress of a TC17 titanium alloy with good correlation and generalization.


2017 ◽  
Vol 54 (2) ◽  
pp. 248-257 ◽  
Author(s):  
Hayder Mohammed Salim Al-Maamori ◽  
M. Hesham El Naggar ◽  
Silvana Micic

Queenston shale is a rock formation located in southern Ontario in Canada that exhibits time-dependent deformation behaviour induced by water penetration. Microtunnelling is an efficient technique that can be used to construct pipelines and tunnels in Queenston shale. In this technique, lubricant fluids, such as bentonite solution and polymer solution, are utilized, which can have a significant impact on the time-dependant deformation (i.e., swelling) of Queenston shale within their depth of influence. A test procedure was developed in this research to investigate the depth of penetration of lubricant fluids and water in Queenston shale. These fluids were applied under pressure, similar to that used in the microtunnelling process, on Queeenston shale specimens. The depth of penetration of these fluids into the test specimens was monitored with time. It was concluded that the penetration depth varied for the various fluids considered. Water had the deepest penetration into Queenston shale. Based on the observed results, an equation is developed to predict the depth of penetration of various fluids in the Queenston shale mass. Results of this research can assist in evaluating the depth of influence of various fluids in Queenston shale and the associated swelling zone can be predicted.


1990 ◽  
Vol 112 (1) ◽  
pp. 62-68
Author(s):  
M. G. Karfakis

The in-situ deformability of rocks and the state-of-stress must be known for the analysis and design of surface and underground structures. This paper presents a method for determining the in-situ deformability of rock-masses using friction gages. Friction gages utilize the friction between the gage and the rock surface for detecting the strain changes. The method involves impressing friction gages on two opposite quadrants of the borehole wall, then radially loading the other two quadrants over 45-deg contact with a self-equilibrating pair of forces of sufficient magnitude to initiate and propagate tensile fractures. While loading, the friction gages detect the tangential strains on the borehole wall before, during and after fracturing of the rock. From the linear portion of the tangential stress-strain data, the elastic properties of the rock can be determined using the appropriate relationships. Furthermore, from the failure and post-failure portions of the tangential stress-strain data the tensile strength of the rock-mass and the in-situ state-of-stress can also be estimated. The theoretical basis of the method, and the fabrication, calibration and testing of the friction gage system, are described. Furthermore, practical field applications of the method are given.


2019 ◽  
Vol 92 ◽  
pp. 01008
Author(s):  
Giorgia Di Remigio ◽  
Irene Rocchi ◽  
Varvara Zania

Paleogene clays are highly plastic, stiff clays deposited between 65.5 and 43 millions of years ago, frequently met in northern Europe. As they were deposited before the Quaternary, they experienced the glacial cycles that occurred in that period. The evolution and movement of the ice masses above the Paleogene clays highly influenced their stress history. During the interglacial periods the glaciers melted, unloading the underlying formations while during the glacial periods the glaciers mass loaded the Paleogene clays and sheared their shallower layers. Previous studies examined the compressibility and swelling of Danish Paleogene clays, and showed an early preconsolidation stresses, lower than that associated with the overburden pressure. This phenomenon was attributed to the effects of the glaciers movements. Other factors that have not been investigated yet and influence the deformation behaviour, can be associated with the micro and nano structure, meaning the particle orientation, and the mineralogical composition of the clays. This study focuses on a Danish Paleogene Formation called Røsnæs clay and the aim is to investigate the macromechanical swelling behaviour and its relation with particle rearrangement. A combination of 1D compression tests, microscopy imaging, mercury intrusion porosimetry and X-ray diffraction tests were performed on reconstituted and undisturbed samples in order to investigate the fabric, the pore structure and the mineralogy of the soil. A synthetic saline solution reproducing the in situ water was used to prepare the reconstituted samples and for the water bath. Variations with the swelling index were correlated with the clay particles rearrangement taking in to account the mineralogical composition. The compression curves and the scanning electron microscope micrographs were correlated with the mercury intrusion porosimeter results.


1980 ◽  
Vol 17 (1) ◽  
pp. 74-88 ◽  
Author(s):  
V. R. Parameswaran

Uniaxial unconfined compression tests were carried out on frozen saturated Ottawa sand containing about 20% by weight of water, at temperatures between −2 and − 15°C, and at strain rates varying between 10−7 and 10−2 s−1. The compressive strength and the initial tangent modulus increased with increasing strain rate and with decreasing temperature. At −2°C, values of strength and modulus were considerably lower than those predicted by linear extrapolation of the values observed at lower temperatures, on a log–log scale. This could be due to the presence of unfrozen water in the samples at −2°C.


2008 ◽  
Vol 45 (3) ◽  
pp. 367-376 ◽  
Author(s):  
Adriano Virgilio Damiani Bica ◽  
Luiz Antônio Bressani ◽  
Diego Vendramin ◽  
Flávia Burmeister Martins ◽  
Pedro Miguel Vaz Ferreira ◽  
...  

This paper discusses results of laboratory tests carried out with a residual soil originated from the weathering of eolian sandstone from southern Brazil. Parent rock features, like microfabric and particle bonding, are remarkably well preserved within this residual soil. Stiffness and shear strength properties were evaluated with consolidated drained (CID) and consolidated undrained (CIU) triaxial compression tests. Undisturbed specimens were tested with two different orientations between the specimen axis and bedding surfaces (i.e., parallel (δ = 0°) or perpendicular (δ = 90°)) to investigate the effect of anisotropy. When CID triaxial tests were performed with δ = 0°, the yield surface associated with the structure was much larger than when tests were performed with δ = 90°. Coincidently, CIU tests with δ = 0° showed peak shear strengths much greater than for δ = 90° at comparable test conditions. Once the peak shear strength was surpassed, CIU tests followed collapse-type effective stress paths not shown by corresponding tests with remolded specimens. A near coincidence was observed between the yield surface determined with CID tests and the envelope of collapse-type effective stress paths for δ = 0° and δ = 90°.


2011 ◽  
Vol 48-49 ◽  
pp. 483-486
Author(s):  
Cheng Liang Hu ◽  
Zhen Zhao ◽  
Ying Zhang ◽  
Xiang Long Xu

40Cr steel is categorized as quenched-tempered steels and is widely used in gears, bolts, couplings, spindles, etc. To study the plastic deformation behaviour of the steel after quenching and tempering, compression and double-pass compression tests have been carried out. The quenched samples are tempered at the temperature of 540oC, 580oC, 600oC and 630oC, and the microstructures, compression load, hardness after compression and load of double-pass compression are investigated. The compression peak load is higher when the tempering temperature is lower. The hardness average and its increase amplitude decrease with the tempering temperature. An interesting phenomenon of the double-pass compression load can be well explained by the microstructures.


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