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Harunur Rashid - One of the best experts on this subject based on the ideXlab platform.
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slope instability on a shallow contourite dominated continental margin southeastern grand banks eastern canada
Marine Geology, 2017Co-Authors: Harunur Rashid, Kevin Mackillop, J Sherwin, David J W Piper, B Marche, M VermootenAbstract:Abstract Submarine sediment failures and related mass-transport deposits (MTDs) are widespread on the eastern Canadian continental slope settings and in general, have been related to ice sheets crossing the outer shelf. The southeastern Grand Banks margin was not glaciated in the last 10 5 years and has a deep shelf break. As a result, the upper continental slope consists principally of sediment transported from the north by the Labrador Current. High-resolution seismic profiles and 10-m long piston cores show widespread sediment failure and MTDs in a plastered contourite drift from 500 to 1000 m water depth. This study documents the stratigraphy of the past 48,000 years and the record of sediment failure events. Heinrich layers H1 to H5 have been recognized from distinctive petrology, physical properties, and bulk geochemistry and are constrained by numerous 14 C-AMS dates. The geotechnical analysis shows that the latest Quaternary sediment section is mildly underconsolidated, perhaps related to high sedimentation rates (up to 0.5 m/ka) enhanced by some leakage of deep fluids. Nevertheless, factor of safety calculations using Su/P 0 and friction angles from triaxial testing suggest the slope is statically stable up to gradients of 9°. Atterberg Limit measurements of silty contourite sediments indicate susceptibility to liquefaction under cyclic loading. There is evidence that apparently synchronous failure occurred over many tens of kilometres of the slope, probably as a result of rare passive margin earthquakes. These shallow water contourite deposits have a higher sand and coarse silt content, much less biogenic material, and more rapid variations in sediment and geotechnical properties than those of the deep-water equivalents, all of which make them more susceptible to sediment failure.
M Vermooten - One of the best experts on this subject based on the ideXlab platform.
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slope instability on a shallow contourite dominated continental margin southeastern grand banks eastern canada
Marine Geology, 2017Co-Authors: Harunur Rashid, Kevin Mackillop, J Sherwin, David J W Piper, B Marche, M VermootenAbstract:Abstract Submarine sediment failures and related mass-transport deposits (MTDs) are widespread on the eastern Canadian continental slope settings and in general, have been related to ice sheets crossing the outer shelf. The southeastern Grand Banks margin was not glaciated in the last 10 5 years and has a deep shelf break. As a result, the upper continental slope consists principally of sediment transported from the north by the Labrador Current. High-resolution seismic profiles and 10-m long piston cores show widespread sediment failure and MTDs in a plastered contourite drift from 500 to 1000 m water depth. This study documents the stratigraphy of the past 48,000 years and the record of sediment failure events. Heinrich layers H1 to H5 have been recognized from distinctive petrology, physical properties, and bulk geochemistry and are constrained by numerous 14 C-AMS dates. The geotechnical analysis shows that the latest Quaternary sediment section is mildly underconsolidated, perhaps related to high sedimentation rates (up to 0.5 m/ka) enhanced by some leakage of deep fluids. Nevertheless, factor of safety calculations using Su/P 0 and friction angles from triaxial testing suggest the slope is statically stable up to gradients of 9°. Atterberg Limit measurements of silty contourite sediments indicate susceptibility to liquefaction under cyclic loading. There is evidence that apparently synchronous failure occurred over many tens of kilometres of the slope, probably as a result of rare passive margin earthquakes. These shallow water contourite deposits have a higher sand and coarse silt content, much less biogenic material, and more rapid variations in sediment and geotechnical properties than those of the deep-water equivalents, all of which make them more susceptible to sediment failure.
Kusnianti Neni - One of the best experts on this subject based on the ideXlab platform.
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PEMANFAATAN MINERAL ASBUTON SEBAGAI BAHAN STABILISASI TANAH
Direktorat Bina Teknik Jalan dan Jembatan, 2018Co-Authors: Kusnianti NeniAbstract:Asbuton is natural asphalt from Buton Island with great deposits and can beutilized, as a road material because it contains not only bitumen but also mineral with high lime content (CaCO3). The development of pure asbuton product, as a result of separation between bitumen and its mineral, so that mineral asbuton will be an environmental problem, if it is not utilized properly. Therefore, research is required to utilized the asbuton mineral as an alternative material for soil stabilization. The purpose of this research is to evaluate soil characteristics by laboratory test after stabilized with mineral asbuton and to find out the right proportion of mineral asbuton to improve soil support. In this research,soil characteristics stabilized mineral asbuton is compare with unstabilized soil to find out soil characteristics changes. The characteristics tested are Atterberg Limit, gradation, density based on standard proctor density, CBR and unconfined compressive strength (UCS). Key words : asbuton mineral, soil stabilisati on, soil characteristics, CBR, UCSAsbuton merupakan aspal alam dari di Pulau Buton dengan deposit yang sangat besar dapat dimanfaatkan sebagai bahan jalan karena disamping mengandung bitumen, mineralnya pun memiliki kandungan kapur (CaCO3) yang cukup tinggi. Dengan dikembangkannya produk asbuton murni sebagai hasil pemisahan antara bitumen dengan mineralnya, maka mineral asbuton tersebut dimasa yang akan datang apabila tidak dimanfaatkan akan mengganggu lingkungan. Oleh karena itu perlu adanya penelitian untuk memanfaatkan mineral tersebut sebagai alternatif bahan stabilisasi tanah. Adapun tujuan dari penelitian ini adalah untuk mengevaluasi karakteristik tanah setelah distabilisasi mineral asbuton melalui pengujian di laboratorium, sehingga didapatkan proporsi mineral asbuton yang sesuai untuk meningkatkan daya dukung tanah. Pada penelitian ini, karakteristik tanah hasil stabilisasi tanah dengan mineral asbuton dibandingkan dengan tanah aslinya untuk mengetahui perubahan karakteristik yang terjadi. Karakteristik yang diuji adalah: batas Atterb erg, gradasi, kepadatan berdasarkan standar Proctor, CBR dan kuat tekan bebas (Unconfined Compressive Strength, UCS). Kata kunci: mineral asbuton, stabilisasi tanah, karakteristi tanah, CBR, kuat tekan bebas
Thaveesak Vangpaisal - One of the best experts on this subject based on the ideXlab platform.
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investigation of the effects and degree of calcium exchange on the Atterberg Limits and swelling of geosynthetic clay liners when subjected to wet dry cycles
Geotextiles and Geomembranes, 2007Co-Authors: Abdelmalek Bouazza, Stephan Jefferis, Thaveesak VangpaisalAbstract:Abstract In the field, particularly in landfill cover system applications, a geosynthetic clay liner may be exposed to inorganic cations such as calcium, magnesium and aluminium which can alter the performance of the GCL bentonite component especially if accompanied by drying and re-wetting as a result of seasonal changes in temperature and rainfall. To investigate the impacts of wetting and drying, the Atterberg Limits of the GCL bentonite component and swelling of the GCL were determined under wet–dry cycling with calcium chloride solution used for the wetting cycles. From the quantities of calcium chloride added at each wetting stage, estimates were made of the degree of ion exchange of calcium for sodium on the clay. The authors recognise that there is a substantial literature on the effects of inorganic salts such as calcium chloride on the behaviour of bentonite. However, so far as they are aware, the results of such tests involving cation exchange have not been investigated in terms of the degree of exchange achieved. In the tests two calcium chloride solutions were used: 0.0125 and 0.125 M. This allowed a detailed investigation of the effects of the degree of sodium–calcium exchange on the bentonite and some, though more Limited, consideration of the effects of ionic strength of the pore fluid. It is shown that for Atterberg Limit tests, even using 0.125 M calcium chloride solution, full calcium exchange could not be achieved as the amount of liquid added to bring the bentonite to the liquid or plastic Limit did not contain sufficient calcium ion for full exchange. For the swell tests, much higher liquid-to-solid ratios were used so that near full exchange could be achieved though only after several wet–dry cycles. Using these data the paper develops a methodology for estimating the position of the cation exchange equilibrium and shows how complex this analysis can become. It also shows that on occasion only Limited cation exchange may be achieved in laboratory tests whereas near full exchange may occur in the field. If the effects of full/near full exchange are to be investigated, laboratory procedures must be specially designed to achieve high degrees of exchange, for example, by using multiple exchange cycles, large liquid-to-solid clay ratios or by permeating the clay with the cation exchange liquid—though such permeation procedures may take a very substantial time.
B Marche - One of the best experts on this subject based on the ideXlab platform.
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slope instability on a shallow contourite dominated continental margin southeastern grand banks eastern canada
Marine Geology, 2017Co-Authors: Harunur Rashid, Kevin Mackillop, J Sherwin, David J W Piper, B Marche, M VermootenAbstract:Abstract Submarine sediment failures and related mass-transport deposits (MTDs) are widespread on the eastern Canadian continental slope settings and in general, have been related to ice sheets crossing the outer shelf. The southeastern Grand Banks margin was not glaciated in the last 10 5 years and has a deep shelf break. As a result, the upper continental slope consists principally of sediment transported from the north by the Labrador Current. High-resolution seismic profiles and 10-m long piston cores show widespread sediment failure and MTDs in a plastered contourite drift from 500 to 1000 m water depth. This study documents the stratigraphy of the past 48,000 years and the record of sediment failure events. Heinrich layers H1 to H5 have been recognized from distinctive petrology, physical properties, and bulk geochemistry and are constrained by numerous 14 C-AMS dates. The geotechnical analysis shows that the latest Quaternary sediment section is mildly underconsolidated, perhaps related to high sedimentation rates (up to 0.5 m/ka) enhanced by some leakage of deep fluids. Nevertheless, factor of safety calculations using Su/P 0 and friction angles from triaxial testing suggest the slope is statically stable up to gradients of 9°. Atterberg Limit measurements of silty contourite sediments indicate susceptibility to liquefaction under cyclic loading. There is evidence that apparently synchronous failure occurred over many tens of kilometres of the slope, probably as a result of rare passive margin earthquakes. These shallow water contourite deposits have a higher sand and coarse silt content, much less biogenic material, and more rapid variations in sediment and geotechnical properties than those of the deep-water equivalents, all of which make them more susceptible to sediment failure.
