Experimental Study on Creep of Highly-Weathered Breccia

Mechanical property of rock is the main research object of rock mechanics. In order to further learn the rheological characteristics of soft fractured rock mass, the creep test of highly-weathered breccia with different water content of 0.65%, 1.88%, 4.03% using low-intensity uniaxial creepmeter developed by Shandong University is processed, and the strain-time curves under different water conditions and the corresponding variation of creep curves with different stress levels and moisture states are obtained. The experimental results show that the higher water content is, the larger creep deformation is and the longer time of creep deformation reaching stable is, in other words, the influence of water content on the rheological characteristics of rock mass is also significant. Finally, the conclusion that softening critical load (long-term strength) and softening critical depth of soft rock are greatly reduced due to the effect of water on rock structure and mechanical parameters is obtained to provide the fundamental reference for the follow-up tests and similar engineering.

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Rheological Characteristics of Weak Rock Mass and Effects on the Long-Term Stability of Slopes

Rock Mechanics and Rock Engineering ◽

10.1007/s00603-013-0527-z ◽

2013 ◽

Vol 47 (6) ◽

pp. 2253-2263 ◽

Cited By ~ 15

Author(s):

Tianhong Yang ◽

Tao Xu ◽

Hongyuan Liu ◽

Chunming Zhang ◽

Shanyong Wang ◽

...

Keyword(s):

Rock Mass ◽

Weak Rock ◽

Rheological Characteristics ◽

Term Stability ◽

Long Term Stability ◽

Stability Of Slopes ◽

Weak Rock Mass

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Study on the Creep Constitutive Model of a Sandstone Rock under the Water-Rock Interaction

Advances in Civil Engineering ◽

10.1155/2021/6648421 ◽

2021 ◽

Vol 2021 ◽

pp. 1-10

Author(s):

Zuosen Luo ◽

Zuoxiang Zhu ◽

Jianlin Li ◽

Lehua Wang ◽

Qiao Jiang ◽

...

Keyword(s):

Rock Mass ◽

Constitutive Model ◽

Nonlinear Creep ◽

Rock Interaction ◽

Long Term Stability ◽

Sandstone Rock ◽

Influence Of Water ◽

Creep Constitutive Model ◽

Water Rock Interaction

With the continuous construction of large-scale geotechnical engineering, more and more attention has been paid to the long-term stability of rock mass engineering, especially the problem of rock creep under the influence of water. Combined with the author’s previous research on the triaxial creep characteristics of sandstone under water-rock interaction, a nonlinear creep constitutive model was established to capture the degradation behavior of a sandstone rock due to cyclic wetting and drying of the reservoir water. Due to the limitations of the visco-elastoplastic model, a thorough modification was done to account the effect of the water-rock interaction on the mechanical degradation of the sandstone rock. Finally, the predicted results were proved to be in a good agreement with the experimental results. Moreover, the strong correlations between the predicted results and the experimental results show the effectiveness of the modified model to scrutinize the nonlinear creep behavior of sandstone rock. Relevant research results have important theoretical significance for the accurate prediction and effective control of the long-term stability of rock mass engineering under the influence of water-rock interaction.

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The December 2008 Crammont rock avalanche, Mont Blanc massif area, Italy

Natural Hazards and Earth System Science ◽

10.5194/nhess-11-3307-2011 ◽

2011 ◽

Vol 11 (12) ◽

pp. 3307-3318 ◽

Cited By ~ 32

Author(s):

P. Deline ◽

W. Alberto ◽

M. Broccolato ◽

O. Hungr ◽

J. Noetzli ◽

...

Keyword(s):

Rock Mass ◽

Fractured Rock ◽

Back Analysis ◽

Rock Avalanche ◽

Western Alps ◽

Seepage Water ◽

Permafrost Degradation ◽

Rock Wall ◽

Air Temperatures ◽

Rock Structure

Abstract. We describe a 0.5 Mm3 rock avalanche that occurred in 2008 in the western Alps and discuss possible roles of controlling factors in the context of current climate change. The source is located between 2410 m and 2653 m a.s.l. on Mont Crammont and is controlled by a densely fractured rock structure. The main part of the collapsed rock mass deposited at the foot of the rock wall. A smaller part travelled much farther, reaching horizontal and vertical travel distances of 3050 m and 1560 m, respectively. The mobility of the rock mass was enhanced by channelization and snow. The rock-avalanche volume was calculated by comparison of pre- and post-event DTMs, and geomechanical characterization of the detachment zone was extracted from LiDAR point cloud processing. Back analysis of the rock-avalanche runout suggests a two stage event. There was no previous rock avalanche activity from the Mont Crammont ridge during the Holocene. The 2008 rock avalanche may have resulted from permafrost degradation in the steep rock wall, as suggested by seepage water in the scar after the collapse in spite of negative air temperatures, and modelling of rock temperatures that indicate warm permafrost (T > −2 °C).

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Seepage Evolution Model of the Fractured Rock Mass under High Seepage Pressure in Dam Foundation

Advances in Civil Engineering ◽

10.1155/2021/8832774 ◽

2021 ◽

Vol 2021 ◽

pp. 1-18

Author(s):

Erfeng Zhao ◽

Yufeng Jiang

Keyword(s):

Rock Mass ◽

Fractured Rock ◽

Constitutive Models ◽

Storage Period ◽

Creep Damage ◽

Fractured Rock Mass ◽

Dam Foundation ◽

Compression Creep ◽

Seepage Characteristics

The seepage of the fractured rock mass in dam foundations involves complex fluid-structure coupling behavior, due to practical hydrogeological conditions. In this work, the seepage characteristics of the fractured rock mass and their correlations with the structural permeable mediums are experimentally explored to reveal the cracking effect on the hydromechanical properties firstly. Subsequently, the tangential and the compression creep damage constitutive models are, respectively, established by introducing a nonlinear viscoplastic body to improve the Nishihara model. Afterwards, an innovative evolution equation of the permeability coefficient considering the creep damage is proposed. It can indicate the time effect of the porosity, the permeability, and damage variables of the fractured rock mass under the long-term infiltration action of the hydraulic pressures. Ultimately, the proposed methods are applied to the seepage simulation on the dam foundation of the Longyangxia hydropower station and the significantly increased leakage is in good agreement with the measured values during the storage period. It was further confirmed that the crack expansion and penetration in the rock masses can be constantly intensified by the seepage pressures. The research results can provide a reference for engineering repair and supervision through controlling the permeability performance for long-term operations.

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Influence of water content on seismic activity of rocks mass in apatite mining in Khibiny

Gornyi Zhurnal ◽

10.17580/gzh.2021.01.06 ◽

2021 ◽

pp. 31-36

Author(s):

A. A. Kozyrev ◽

◽

S. A. Zhukova ◽

A. S. Batugin ◽

◽

...

Keyword(s):

Rock Mass ◽

Water Content ◽

Snow Melting ◽

Mining Operations ◽

Principal Mechanism ◽

Rockburst Hazard ◽

Tectonic Disturbances ◽

Weakened Rock ◽

Influence Of Water ◽

Seismic Background

The authors analyze connection between the rock mass water content due to surface water (precipitation, snow melting and water bodies) and rock bursts in mines. The seismological monitoring performed from 2001 at the surroundings of the Apatite Circus and Rasvumchorr Plateau apatite deposits identified fluctuation of the general seismic background from year to year and seasonably. For these deposits, increased water content of rocks is seen as a natural trigger for rock mass seismicity during intensive rains and snow melting. The 15 year-long seismic monitoring of the apatite deposits under study has revealed regularity in a seasonal growth of seismicity during snow melting and precipitations, mainly in spring months. Particularities of geodynamical event occurrence allow a conclusion on the ultimately stress state of the upper earth’s crust in whole in the deposits’ vicinities. Reactivation of tectonic disturbances and weakened rock mass zones occurring due to relief of normal compression during infiltration can be a potential principal mechanism of seismic activation of the rock mass during the increased water content periods. The origin of the events observed is linked with the dynamic release of ultimate rock mass stresses when geomechanical conditions change under the action of hydrostatic pressure on tectonically disturbed zones. The authors make a conclusion on necessity to apply the revealed regularities of impact of natural factors on rockburst hazard when planning mining operations and performing geomechanical monitoring.

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DISTRIBUTION OF SULFATE WATER IN GRASBERG BLOCK CAVE (GBC) MINE, PAPUA, INDONESIA

RISET Geologi dan Pertambangan ◽

10.14203/risetgeotam2017.v27.440 ◽

2017 ◽

Vol 27 (1) ◽

pp. 77

Author(s):

Jaka Satria Budiman ◽

I Gde Basten ◽

Hendri Silaen ◽

Rahardian Ryan Ruthman ◽

Fari Fathiardi Putra ◽

...

Keyword(s):

Water Content ◽

Fractured Rock ◽

Chemical Compounds ◽

Sulfate Attack ◽

Underground Mine ◽

Chemical Information ◽

Geological Data ◽

Ground Support ◽

Ore Body

Grasberg Block Cave (GBC) underground mine, which is operated by PT Freeport Indonesia, located at High Land of Papua which has intensity of rainfall (average 4000 mm/year) and causing water inflow through the fractured rock, and flowing inside the underground mine. The water occurrence inside the underground mine could be in seepage form and water flow from diamond drilling hole. Water seepage inside underground mine contain many chemical compounds such as sulfate (SO42-). Sulfate has ability to cause acid water and sulfate attack, which can be a problem for ground support existing. Water from seepages of existing drift during development were collected and sent to laboratory to obtain detail chemical information. By correlating with geological data (formation and its content), distribution of water sulfate can be known. In the ore body of GBC, sulfate water content is higher than other lithologies. These data can be used for long term ground support planning in the future.AbstrakTambang bawah tanah Grasberg Block Cave (GBC) yang dioperasikan oleh PT Freeport Indonesia, berlokasi di dataran tinggi Papua mempunyai curah hujan yang tinggi (rata-rata 4000 mm/tahun) dan menyebabkan adanya aliran air melewati rekahan batuan dan mengalir menuju ke dalam tambang bawah tanah. Keberadaan air di dalam tambang bawah tanah dapat berupa rembesan dan aliran air yang mengalir dari dalam lubang pengeboran. Rembesan air di dalam tambang bawah tanah mengandung banyak senyawa kimia seperti senyawa yang memiliki sulfat (SO42-). Sulfat mempunyai kemampuan untuk menyebabkan air asam dan sulfate attack, yang notabene bisa menjadi masalah terhadap ground support yang ada. Air yang terdapat di terowongan tambang bawah tanah, diambil dan dikirim menuju laboratorium untuk mendapatkan informasi kimia secara rinci. Dengan melakukan korelasi terhadap data geologi (formasi dan kandungan mineralnya), distribusi dari air sulfat bisa diketahui. Di dalam tubuh bijih utama GBC, air mengandung sulfat lebih tinggi dibandingkan dengan di area litologi lainnya. Data-data ini bisa digunakan untuk perencanaan pemasangan penyangga batuan di masa yang akan datang.

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Creep Fracture Characteristics of Fractured Rock Mass Strengthened with Toughened Epoxy Resin

Advances in Civil Engineering ◽

10.1155/2021/1582745 ◽

2021 ◽

Vol 2021 ◽

pp. 1-8

Author(s):

Jun Wang ◽

Junjie Xu ◽

Zhipeng Nie ◽

Lin Liu ◽

Min Qin ◽

...

Keyword(s):

Rock Mass ◽

Epoxy Resin ◽

Fractured Rock ◽

Creep Model ◽

Term Strength ◽

Fractured Rock Mass ◽

Opening Displacement ◽

Toughened Epoxy ◽

Powder Content

For improving the toughness and long-term strength of the fractured rock mass reinforced with epoxy resin and reducing the opening displacement of the crack tip, three types of converging cracks are established according to the deformation and failure characteristics of the rock mass, structural planes, and epoxy resin composite structure. The stress intensity factor of the type II compound crack and the analytical formula of the crack surface tip opening displacement are obtained. An improved Kelvin nonlinear creep model is proposed. Through the creep isochronous curve, the time and long-term strength of accelerated creep failure are obtained, as well as creep rupture coupling characteristics. The ductile plastic deformation is used to characterize the toughness, and the toughness of epoxy resin is enhanced by adding mud powder, and the relationship between toughness and long-term strength is established. Combined with experimental verification, when the drying mud powder content is 20%, the toughness of the epoxy resin has a good correlation with the long-term strength; when the mud powder content exceeds 30%, its ductility and long-term strength decrease, and at the same time the toughness effect is significantly weakened. The research results can provide a useful reference for toughened epoxy resin to strengthen fractured rock mass engineering.

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