China 
Africa 
Explore chapters and articles related to this topic
Geomechanical characterization of the upper carboniferous under thermal stress for the evaluation of a High Temperature-Mine Thermal Energy Storage (HT-MTES)
Published in Vladimir Litvinenko, EUROCK2018: Geomechanics and Geodynamics of Rock Masses, 2018
Florian Hahn, Theresa Jabs, Rolf Bracke, Michael Alber
Based on the failure criteria, it can be stated that, with the exception of claystone, all of the other tested rock types exhibit a decrease in their rock strength between 28 and 51%, regarding the initial and final measurements after 30 heating cycles. The results of the coarse grained sandstones have not been taken into consideration for this evaluation, as the variances in their results do not display any clear trends. Interestingly, the claystone shows an increased rock strength of up to 46% after the conclusion of the test series. This can be explained by the fact that the thermal cyclic loading induces shear stress within the sample and hence a reduction of the attractive forces between the clay particles takes place, resulting in compaction. Overall, this leads to a structure densification, which enables the claystone to withstand higher loading rates (Cekerevac and Laloui 2004).
Diagenesis and Properties of Sedimentary Rocks
Published in Aurèle Parriaux, Geology, 2018
We use the term claystones (or mudstones) for argillaceous rocks, thus reserving the name clay for recent loose sediments (other definitions exist in the literature). Claystones (Fig. 10.13) are detrital rocks composed primarily of clay particles; accessory minerals are quartz (silty claystones) and calcite (transition to marls). In outcrop, claystones often have a layered appearance caused by the parallel organization of clay minerals during sedimentation and compaction (thus equivalent to the term “shale” used by Anglo-Saxons). These rocks generally indicate sedimentation relatively far from the mouths of rivers.
Diagenesis and Properties of Sedimentary Rocks
Published in Aurèle Parriaux, Geology, 2018
We use the term claystones (or mudstones) for argillaceous rocks, thus reserving the name clay for recent loose sediments (other definitions exist in the literature). Claystones (Fig. 10.13) are detrital rocks composed primarily of clay particles; accessory minerals are quartz (silty claystones) and calcite (transition to marls). In outcrop, claystones often have a layered appearance caused by the parallel organization of clay minerals during sedimentation and compaction (thus equivalent to the term “shale”). These rocks generally indicate sedimentation relatively far from the mouths of rivers.
Excavation induced over pore pressure around drifts in the Callovo-Oxfordian claystone
Published in European Journal of Environmental and Civil Engineering, 2023
Minh-Ngoc Vu, Lina María Guayacán Carrillo, Gilles Armand
First, a qualitatively analysis is performed, based in a closed-form solution of stress field around an elliptical opening, embedded in a transversely isotropic rock. The results show that the elliptical shape of fractured zone and the elastic anisotropy induce a compression in the horizontal direction of the cross section and an extension on the vertical one. The pore pressure relates to the volumetric strain based on the equivalence between a purely mechanical problem and a hydromechanical one under undrained condition. Accounting a low permeability of claystone, the excavation is performed in a quasi-undrained condition. Accordingly, a compressive volumetric strain generates an overpressure n the horizontal direction, while an extensional volumetric strain provokes a depression in the vertical one. Moreover, it has been observed that, higher ratio between the major and minor axes of the elliptical opening, results in an increase in magnitude of the overpressure inside the rock.
Mechanical properties of clayey soil relevant for clogging potential
Published in International Journal of Geotechnical Engineering, 2018
Yolanda Alberto-Hernandez, Chao Kang, Yaolin Yi, Alireza Bayat
The geology of Edmonton has been defined by the northern Beverly Valley, the surrounding Rocky Mountains and the Saskatchewan River. Generally, it consists of bentonitic sandstone, siltstone, claystone, coal seams with bentonite beds and glacial lake sediments (Bayrock and Berg 1966). In the zones where the soil was sampled, the deposits can be summarised as glacial lake Edmonton sediments, glacial till, preglacial Saskatchewan sands and gravels, and a bedrock made up of sandstone, shale and coal of the Edmonton formation (Bayrock and Berg 1966). Bayrock and Hughes (1962) sampled soil at different locations and depths in Edmonton. At each specified depth, several samples were collected and sieve analyses were carried out for each of them. Particle size distribution can be obtained after sieving using US standard screens (Bayrock 1955). For material finer than 0.062 mm, it was dried and sedimentation analyses were carried out by pipette method as stated by Toogood and Peters (1953). Six samples were collected and analysed by Bayrock and Hughes (1962) at the depth at which the authors sampled the soil in this study. Results show that average percentages of each composition are 44, 30 and 26%, respectively. The samples, collected from the tunnel sites on the south side of Edmonton, are classified as till. In order to appropriately evaluate their consistency index in the field, fresh samples were placed immediately in the moisture room. They were selected because till has caused clogging during tunnel excavation in the city. Currently, construction staffs use water and foam to reduce the stickiness of soil.
Integration of SPOT-5 and ASTER satellite data for structural tracing and hydrothermal alteration mineral mapping: implications for Cu–Au prospecting
Published in International Journal of Image and Data Fusion, 2018
Reyhaneh Ahmadirouhani, Mohammad-Hassan Karimpour, Behnam Rahimi, Azadeh Malekzadeh-Shafaroudi, Amin Beiranvand Pour, Biswajeet Pradhan
In the band ratio of 6/7, 5/6 and 4/6 in RGB (Figure 6(b)), the areas in yellow to orange colour represent the high abundance of the mixture of Al-OH minerals (mostly phyllic and argillic zones) and Fe-OH minerals (jarosite). In this transformation, phyllic alteration zone is strongly enhanced in the resultant image map (Figure 6(b)) due to the effect of high Al-OH and Fe-OH absorption features in bands 6 and 7 of ASTER. In this image map, unaltered lithologies and limestone appear as blue to purple colour, which enhances due to the contribution of band ratio of 4/6. The green colour pixels (related pixels to band ratio of 5/6) are mostly alluvial deposits, sedimentary rocks (slate, conglomerate, phyllite and sandstone) and other igneous rocks with low content of Al-OH altered minerals. Sedimentary rocks, such as mudstone, shale, claystone and litharenite sandstones contain large amounts of detrital clays, such as montmorillonite, illite and kaolinite (Mars and Rowan 2006). Hence, they are manifested as the green tone in the image map (Figure 6(b)).