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Soils, rocks, and groundwater
Published in Rodrigo Salgado, The Engineering of Foundations, Slopes and Retaining Structures, 2022
Soil is created from the weathering of rocks. Weathering is the physical breakdown of rocks and/or the chemical transformation of rock minerals into other minerals. Chemical weathering is enhanced by relatively high temperatures and humidity, such as those that exist in tropical and subtropical areas. In arid regions, physical weathering predominates. Physical weathering usually precedes and facilitates chemical weathering, as it opens up fractures and other pathways for water to penetrate the rock and facilitate mineral degradation. For example, plant roots may penetrate some of the vertical fractures existing in granite due to the stress relief caused by erosion and in basalt from the fast cooling, opening them up for penetration of large amounts of water. The water is usually slightly acidic, reacting with the rock minerals to produce other minerals that are more chemically stable.
Basic Geology and Hydrogeology
Published in Jimmy H.C. Wong, Chin Hong Lim, Greg L. Nolen, Design of Remediation Systems, 2020
Jimmy H.C. Wong, Chin Hong Lim, Greg L. Nolen
The earth has a crust of granitic and basaltic rock 40 to 130 ft thick. Overlying this solid rock is a relatively thin layer of variable thickness of unconsolidated materials called soil. These materials can vary in size from submicroscopic mineral particles to huge boulders. These unconsolidated materials were formed as a result of weathering and other geologic processes acting on the rocks near the earth’s surface. There are basically two types of weathering processes, physical weathering and chemical weathering.
Groundwater Problems for Excavations in Rock
Published in Pat M. Cashman, Martin Preene, Groundwater Lowering in Construction, 2020
As a general rule, weathering degrades rock and reduces strength. However, the spatial distribution and nature of weathering can vary greatly. Weathering profiles are controlled by many factors, including the original rock type, geological structures, groundwater conditions, topography and climate. Further background on weathered rock can be found in Price (1995) and Hencher and McNicholl (1995).
Data-Driven Multi-Scale Study of Historic Urban Environments by Accessing Earth Observation and Non-Destructive Testing Information via an HBIM-Supported Platform
Published in International Journal of Architectural Heritage, 2023
Georgios Artopoulos, Paris Fokaides, Vasiliki Lysandrou, Marissia Deligiorgi, Panos Sabatakos, Athos Agapiou
In Figure 14, indicative data analytics of input related to weathering mechanisms is presented. This information was extracted by the analysis of the 19 pilot buildings under study. The weathering mechanisms were recognized in accordance with the EIR procedures developed for the purpose of the platform. Weathering refers to the natural phenomenon of the breakdown or dissolution of rocks and minerals, and this can cause deterioration of building materials, provoking the following mechanisms: wet and dry expansion, frost-induced weathering, salt crystallization, biological degradation, chemical weathering, mechanical weathering, and thermal expansion deterioration. This data allows for further forecasting of restoration needs of heritage buildings, as well as the development of a risk assessment for the structural integrity of building assets under study.
Improving geological logging of drill holes using geochemical data and data analytics for mineral exploration in the Gawler Ranges, South Australia
Published in Australian Journal of Earth Sciences, 2021
E. J. Hill, A. Fabris, Y. Uvarova, C. Tiddy
More subtle mineral alteration affects many of the units intersected by MSDP11. Zones of weak pervasive sericite and chlorite alteration are common but do not result in significant chemical variation and therefore are not classified as separate units. Where alteration intensity increases, such as between 260 and 290 m, associated with a zone of chloritised metamorphic biotite within the meta-diorite (Fabris et al., 2017), a distinct sub-domain is evident at a scale of ∼4. However, it is unclear whether changes in Fe, K, Ca and Ti across this interval are directly related to mineral alteration or subtle primary lithological variation. Another form of mineral alteration overprint on primary lithology is the effect of weathering. Weathering involves the chemical breakdown of rocks owing to near-surface processes and is a common overprint that can result in significant chemical modification and therefore make it difficult to differentiate from lithological change (e.g. McQueen & Scott, 2008). In drill hole MSDP11, weathering mainly effects a felsic igneous protolith and results in primary feldspar being replaced by kaolinite to varying degrees down to a depth of 74.5 m. This weathering effect is mapped chemically by a progressive reduction in K and the near total removal of Ca (Figure 17). Even the immobile elements Ti and Nb show some modification. Weathering results in a distinct domain at a scale of ∼40 (between 30 and 70 m); however, confidently distinguishing change owing to weathering rather than primary lithological difference remains a challenge.
Geochemical evolution and quality assessment of groundwater resources at the downstream section of the Kano-Challawa River system, Northwest Nigeria
Published in International Journal of River Basin Management, 2021
Adamu Mustapha, Balarabe Sarki Sagagi, Mohammed Mala Daura, Adamu Idris Tanko, Philip Ogbonnia Phil-Eze, Hamza Ahmad Isiyaka
The high loading on the cations, salinity, conductivity, turbidity and dissolved constituents of groundwater in the study area may be due to the geochemical cycle, which starts with the weathering of basement complex rocks. Weathering breaks up rock minerals and releases elements that react with water and enter into solution. In addition, the vegetative litter releases organic and mineral substances to the soil and groundwater as part of the biochemical cycle. The weathering is more intense in the warm and humid climate of the Kano Region. Rocks can be broken up either by mechanical forces or transformed by chemical reactions. The disintegration of rocks by physical weathering increases the infiltration capacity. The quality of groundwater varies from site to site and season to season due to the variation in chemical composition which is highly dependent on the topography, climate, and mineralogical composition of the bed rock (Salve et al.2011). The long residence time and incomplete flushing of soluble minerals produce groundwater, which generally comprises sodium chloride (Singh et al.2012).