Experimental study on creep deformation and long-term strength of unloading-fractured marble

Under low stress conditions, when the load exerting on the mined-out areas roof is less than the rock long-term strength, the rock roof will generate some creep deformation. In order to prevent the roof of the mined-out areas suddenly collapse, and to ensure the operator and construction equipment above the mined-out areas safety, it is an important security technical problem to reveal the creep characteristics of the shallow mined-out areas roof. Taking the mined-out areas of Antaibao Surface Mine as background, considering the rheological properties of rock roof, and assuming the roof was a rectangular thick plate, the creep characteristics of mined-out areas roof were analysed by applying the thick plate theory and Kelvin creep model. The regression equation of the roof deflection increment over time was given, and the creep characteristics of the shallow mined-out areas roof were revealed also.

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An experimental study of the tenacity time of samples made of high-chromium rotor steel for assessing its long-term strength

Thermal Engineering ◽

10.1134/s0040601508020043 ◽

2008 ◽

Vol 55 (2) ◽

pp. 116-121 ◽

Cited By ~ 1

Author(s):

V. I. Gladshtein ◽

A. V. Pchelintsev ◽

L. D. Chistyakova

Keyword(s):

Experimental Study ◽

Rotor Steel ◽

Term Strength ◽

High Chromium

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Triaxial Creep Behavior of Red Sandstone in Freeze-Thaw Environments

Geofluids ◽

10.1155/2020/6641377 ◽

2020 ◽

Vol 2020 ◽

pp. 1-20

Author(s):

Yongjun Song ◽

Yongxin Che ◽

Leitao Zhang ◽

Jianxi Ren ◽

Shaojie Chen ◽

...

Keyword(s):

Stress Level ◽

Creep Deformation ◽

Transverse Shear ◽

Shear Plane ◽

Confining Pressure ◽

Term Strength ◽

Red Sandstone ◽

Freeze Thaw ◽

Viscoelastic Strain

To investigate the time-dependent mechanical properties of rock masses in cold regions under the effects of freeze-thaw cycling and long-term loading, triaxial multilevel loading and unloading creep tests were performed on saturated red sandstone samples subjected to different numbers of freeze-thaw cycles. The effects of freeze-thaw cycles and confining pressure on the creep properties, long-term strength, and creep failure mode of the rock were analyzed. The effect of freeze-thaw cycles on the microstructure of the rock was analyzed using scanning electron microscopy. The results showed that as the number of freeze-thaw cycles increased, the rock particle boundaries became more distinct, and more pores formed. The effect of freeze-thaw cycles on the creep deformation of red sandstone was related to the loading stress level. At low stress levels, the rock viscoelastic strain increased gradually and almost linearly with an increasing number of freeze-thaw cycles; in contrast, at high stress levels, the rock viscoelastic strain increased nonlinearly. The viscoplastic strain increased almost linearly with increasing freeze-thaw cycles. The fourth loading stress level (70% σ c ) corresponded to the transition of the creep deformation of the red sandstone. When the confining pressure was low, a higher stress level caused the confining pressure to have a more significant effect on the creep strain. However, as the confining pressure continued to increase, the effect of the confining pressure on the creep strain eventually disappeared. The long-term strength of the red sandstone decreased approximately linearly with an increase in the number of freeze-thaw cycles. When the number of freeze-thaw cycles and the confining pressure were high, the rock samples formed a transverse shear plane and were more fragmented than those without a transverse shear plane. These results provide a reference for construction in rock mass engineering and long-term stability analysis in cold regions.

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Experimental Research on Coupling of Swelling Rock between Swelling and Creep

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.353-356.293 ◽

2013 ◽

Vol 353-356 ◽

pp. 293-302

Author(s):

Qiu Yan Fan ◽

Mei Qian Wang ◽

Xian Li ◽

Bo Zhang

Keyword(s):

Creep Deformation ◽

Residual Deformation ◽

Swelling Pressure ◽

Initial Water Content ◽

Term Strength ◽

Compression Tests ◽

Initial Water ◽

Multi Stage ◽

Swelling Rock

Swelling rock has the properties of swelling and creep. Researches on coupling between swelling and creep have not yet been carried out. The expansive Paleogene mudstone is used to laboratory uniaxial compression tests, to find the coupling regularity between swelling and creep under different initial water contents, influent modes and loading methods. For coupling, the creep curves show similar characteristic of non-coupling. The creep deformation increases obviously and the long-term strength decreases comparing with non-coupling. With increasing initial water content, the creep deformation increases for coupling. The creep deformation increases with the enlargement of water-absorption area during the coupling creep. For single-stage and multi-stage loading, the creep regularity is similar to non-coupling. The sample will have a permanent residual deformation when unloaded at the second stable creep stage. The long-term strength of swelling rock is greater than the swelling pressure and the long-term strength is lower than that of non-coupling.

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Experimental Study of Influences of Initial Temperature on Cement Grout Performance

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1095.242 ◽

2015 ◽

Vol 1095 ◽

pp. 242-247 ◽

Cited By ~ 1

Author(s):

Jin Chao Yang ◽

Wan Peng Wang ◽

Shu Guang Wang ◽

Jian Hua Chen ◽

Wei Yang

Keyword(s):

Experimental Study ◽

Initial Temperature ◽

Setting Time ◽

Cement Grout ◽

Curing Temperature ◽

Term Strength ◽

Bleeding Rate ◽

Early Strength

Through the experiment, this paper studies and analyzes influence of different initial temperatures on cement grout performance. The results show initial temperature has influences on grout fluidity, bleeding rate, setting time and early strength. Under guaranteed curing temperature, initial temperature has no influence on long-term strength of grout.

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An Experimental Study on the Frictional Property and Long-Term Performance of GT/HDPE Composites

Materials Science Forum ◽

10.4028/www.scientific.net/msf.539-543.1043 ◽

2007 ◽

Vol 539-543 ◽

pp. 1043-1046

Author(s):

Jung Min Seo ◽

Han Yong Jeon ◽

Beong Bok Hwang ◽

Y.H. Lee ◽

H.S. Koo

Keyword(s):

Experimental Study ◽

Creep Deformation ◽

High Performance ◽

Reduction Factor ◽

Frictional Property ◽

Needle Punching ◽

Punching Process ◽

Long Term Performance ◽

Term Performance

This paper is concerned with the long-term performance of geo-textile (GT) composites in terms of creep deformation and frictional properties. Composites of PVA GT and HDPE GM were made to investigate the advanced properties of long-term performance related to waste landfill applications. The same experiments were also performed for typical polypropylene and polyester GT and compared to PVA GT/HDPE GM composites. The main purpose of this study is to develop high performance GT composites with GM by using PVA GT which is capable of improving frictional property and thus enhances long-term performance of GT composites. In the present experiments, GT composites of PVA GT/HDPE GM, PVA GT of 600, 1000, 1500, 2000g/m2 and HDPE GM were prepared in thermal bonding process. Polyester and polypropylene GT were also made in needle punching process. The creep deformation of GT composites was measured and evaluated in accordance with ASTM D5262. Frictional characteristics of GT composites tested in this study were conducted with compact direct shear apparatus in accordance with ASTM D5321. It was concluded from the present experimental study that friction coefficient of GT composites is relatively large compared with those of polyester and polypropylene non-woven GT as long as the friction media has similar size to the particles of domestic standard earth. In the event that 20% of the maximum tensile strength was added to polypropylene and polyester non-woven geo-textiles, creep deformation reached to 10% or higher, making it even impossible to find reduction factor.

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