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Earth Systems and Cycles
Published in Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough, Earth Materials, 2019
Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough
Metamorphic rocks are igneous, sedimentary, or preexisting metamorphic rocks that have been squeezed, heated, or otherwise substantially altered without melting. Most metamorphic rocks that we see are formed over a range of pressures up to, perhaps, 10,000 atmospheres. Higher pressure rocks generally only form deep within Earth (>30 km) and, as a consequence, are rare at Earth’s surface. Metamorphic temperatures are generally between 200 °C and 750 °C (400 °F to 1400 °F) because at higher temperatures, melting is likely to occur, creating a magma and thus an igneous rock. Heat and pressure, typically due to burial or mountain building, are the main agents of metamorphism. Chemically active fluids, too, may cause metamorphism. Less commonly, shearing associated with movement of active faults produces a special kind of metamorphic rock called a cataclastic rock.
Elastoplastic modelling the creep behaviour of cataclastic rock under multi-stage deviatoric stress
Published in European Journal of Environmental and Civil Engineering, 2018
Y. Zhang, X.D. Zhang, J.F. Shao, Y. Jia, Y.L. Wang
Weak cataclastic rocks are frequently encountered in various engineering applications; the description of creep behaviours of such soft rocks is very important for the analysis of various hydro-mechanical problems, such as dam foundation stability, reservoir subsidence, tunnel support design and hydraulic fracturing.(Chen & Hu, 2003, Zhang, Shao, Xu, Jia, & Zhao, 2015). In general, cataclastic rock is generally characterised by a loose textual structure, a high moisture content, poor physical mechanical properties and poor cemented contacts (Burgi, Parriaux, Franciosi, & Rey, 1999; Gudmundsson, Simmenes, Belinda, & Sonja, 2010; Habimana, Labiouse, & Descoeudres, 2002). Due to difficulties in getting undisturbed specimens and in performing laboratory tests, the creep behaviours of such rocks are so far poorly understood and further experimental investigations are still needed. In the framework of a hydropower construction project in Southwest China, several tectonically fractured zones were encountered. This gave to the present study a good opportunity for modelling the creep behaviours of the cataclastic rocks.