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Soil Mechanics
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
Sediments, which contain loose grains, are unconsolidated materials. Rocks, in contrast, are consolidated, meaning that grains are cemented or otherwise connected to each other to provide rock strength. Rock strength is variable and some rocks, such as poorly cemented shale, have little strength. Shale may break and crush easily and at the surface may weather quickly to punk rock or rotten rock that has properties akin to a sediment. Often, weathered shale can be excavated with a shovel, unlike harder rocks such as granite. Yet, at depth in Earth’s crust, shale can be a good barrier to fluid flow and can resist deformation, even considering its low strength properties. So, is weathered shale a rock or a sediment? When rocks weather at the surface, they eventually become unconsolidated material and perhaps develop soil horizons, but exactly when the transitions occur is often unclear.
Diagenesis and Properties of Sedimentary Rocks
Published in Aurèle Parriaux, Geology, 2018
Several general definitions will be useful: Unconsolidated sediments (or “soils” for geotechnical engineers): masses of particles that are not bound, or are only loosely bound, to each other.Diagenesis: the group of processes that transform unconsolidated sediment into rock. A synonymous term is lithification. In contrast to metamorphism (Chap. 11), the mineralogical modifications that occur with diagenesis involve modest changes of temperature and pressure.Sedimentary rock: a mass of particles sufficiently bound together to behave as a single solid mass.
Basic Principles
Published in Kathleen Sellers, Fundamentals of Hazardous Waste Site Remediation, 2018
A layer of fill covers many sites in developed areas. Fill, which may comprise soil, ashes, and/or mixed debris, was placed at many sites to fill in a wetland and make usable land, to level natural ground contours, or to dispose of waste. Natural geologic formations include unconsolidated deposits and rocks. Unconsolidated deposits are soils originally deposited by glaciers, water (such as river sediments), or wind (such as sand dunes). Unconsolidated deposits include materials such as gravel, sand, silt, and clay. These materials are characterized by their particle size, as indicated in Table 2.6. Rock formations include consolidated sedimentary rocks such as sandstone, shale, and limestone, igneous rocks, and metamorphic rocks such as granite, basalt, slate, or gneiss.
A review on the potential sources and health implications of fluoride in groundwater of Sub-Saharan Africa
Published in Journal of Environmental Science and Health, Part A, 2020
Tobiloba Onipe, Joshua N. Edokpayi, John O. Odiyo
Malawi consists majorly of the Precambrian and Lower Paleozoic crystalline basement rocks which includes gneiss, granulite with some granite. The South-Eastern part of the country is underlined by the Younger Karoo alkaline granitic and syenitic intrusions of the Chilwa complex. The North and extreme south of the country is underlained with the Karoo sediments. The plains around Lakes Nyasa and Chilwa are occupied with Quaternary alluvium, colluvium and lacustrine deposits.[79] The alluvium came from erosion of rock materials majorly from the Rift valley escarpment slopes. The sediments, partly faulted as tectonism along the Rift Valley is still active. The Quaternary deposits consist of unconsolidated mixed clays, silts, sands and gravels.
Seismic performance of an immersed tunnel considering random soil properties and wave passage effects
Published in Structure and Infrastructure Engineering, 2018
Zhiyi Chen, Sunbin Liang, Chuan He
The geological investigations of the project site indicate that the immersed tunnel is constructed on the marine deposits of Zhujiang Estuary plain, which is a fairly flat topography. The strata under the immersed tunnel mainly include two parts. The upper part is unconsolidated sediments that are composed of silt, clay, silty sand, medium sand and gravel sand. The underlying bedrock is made of granite mostly and schist locally. In situ measurements and geotechnical tests are used to determine the basic properties and dynamic characteristics of the soils at the tunnel site. The results of those measurements and tests are presented in Tables 1 and 2.
Geotechnical site characterization of the Lake Urmia super-soft sediments using laboratory and CPTu records
Published in Marine Georesources & Geotechnology, 2020
Abolfazl Eslami, Davood Akbarimehr, Esmail Aflaki, Mohammad Mahdi Hajitaheriha
One of the most accurate and validated tests to determine the shear strength of clayey soils is triaxial testing. Unconsolidated undrained triaxial tests (UU) using undisturbed samples were used to obtain undrained shear strength (Su) of sediments in laboratory experiments (ASTM D2850). Table 2 shows the results of the triaxial experiments and the wet unit weight of the specimens at different depths.