Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Engineering geology of residual soil derived from mudstone in Zimbabwe
Abstract As increasing amounts of civil engineering work are carried out on mudstone-derived residual soils, it has become important to systematically assess their geological engineering properties. Thus, the properties of mudstone-derived residual soils were evaluated in this study via a series of comprehensive laboratory tests to assess physical, mechanical, mineralogical, and microstructural variations. Results show that the physical properties of these soils are inadequate in terms of engineering applications; these soils can be classified as highly plastic clays that are hard to compact. Natural mudstone-derived residual soils undergo severe disintegration underwater while remolded examples are similar but tend to exhibit more stable responses. Natural mudstone-derived residual soils behave in a structured way when subjected to shear and compression; these soil types possess superior natural shear resistance but their strength decreases significantly following saturation as well as in wetting and drying cycles. Data show that the microstructures of mudstone-derived residual soils are characterized by the presence of aggregations with fissures; although iron-bearing cementation between these aggregations is responsible for high soil strength, bonds can be damaged, or even destroyed, when samples are saturated or subjected to wetting and drying cycles leading to a reduction in shear strength. The results of this research provide clear parameters for related engineering applications and enhance our understanding of residual mudstone-derived soils.
Highlights Peculiar features are explained from the aspects of microstructure and mineralogy. Disintegration behavior is quantitatively investigated. The influence of water and wetting-drying cycles are evaluated. Iron-bearing cementation is responsible for high shear strength.
Engineering geology of residual soil derived from mudstone in Zimbabwe
Abstract As increasing amounts of civil engineering work are carried out on mudstone-derived residual soils, it has become important to systematically assess their geological engineering properties. Thus, the properties of mudstone-derived residual soils were evaluated in this study via a series of comprehensive laboratory tests to assess physical, mechanical, mineralogical, and microstructural variations. Results show that the physical properties of these soils are inadequate in terms of engineering applications; these soils can be classified as highly plastic clays that are hard to compact. Natural mudstone-derived residual soils undergo severe disintegration underwater while remolded examples are similar but tend to exhibit more stable responses. Natural mudstone-derived residual soils behave in a structured way when subjected to shear and compression; these soil types possess superior natural shear resistance but their strength decreases significantly following saturation as well as in wetting and drying cycles. Data show that the microstructures of mudstone-derived residual soils are characterized by the presence of aggregations with fissures; although iron-bearing cementation between these aggregations is responsible for high soil strength, bonds can be damaged, or even destroyed, when samples are saturated or subjected to wetting and drying cycles leading to a reduction in shear strength. The results of this research provide clear parameters for related engineering applications and enhance our understanding of residual mudstone-derived soils.
Highlights Peculiar features are explained from the aspects of microstructure and mineralogy. Disintegration behavior is quantitatively investigated. The influence of water and wetting-drying cycles are evaluated. Iron-bearing cementation is responsible for high shear strength.
Engineering geology of residual soil derived from mudstone in Zimbabwe
Zhang, Xianwei (Autor:in) / Liu, Xinyu (Autor:in) / Chen, Cheng (Autor:in) / Kong, Lingwei (Autor:in) / Wang, Gang (Autor:in)
Engineering Geology ; 277
27.07.2020
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
Mudstone residual soil , Engineering geological characteristics , Shear strength , Microstructure , Mineralogy , Iron-bearing cementation , <italic>B</italic> , Skempton pore pressure coefficient , <italic>C</italic> , cohesion , <italic>C</italic> <inf>c</inf> , compression index , <italic>c</italic>'<inf>cu</inf> , effective cohesion , <italic>c</italic> <inf>r</inf> , residual cohesion , <italic>C</italic> <inf>t</inf> , disintegration index , <italic>C</italic> <inf>v</inf> , disintegration rate , <italic>D</italic> , particle diameter , <italic>e</italic> <inf>0</inf> , void ratio , <italic>G</italic> <inf>s</inf> , specific gravity , <italic>i</italic> , hydraulic gradient , <italic>I</italic> <inf>c</inf> , collapse potential , <italic>I</italic> <inf>p</inf> , plasticity index = <italic>w</italic> <inf>L</inf> − <italic>w</italic> <inf>p</inf> , <italic>I</italic> <inf>v</inf> , void index , <italic>k</italic> <inf>v</inf> <italic>, k</italic> <inf>h</inf> , permeability coefficient in the vertical and horizontal direction, respectively , <italic>P</italic> <inf><italic>c</italic></inf> , apparent pre-consolidation pressure for mudstone residual soil , <italic>q</italic> , deviatoric stress , <italic>q</italic> <inf>u</inf> , unconfined compression strength , <italic>s</italic> , horizontal displacement in direct test , <italic>S</italic> <inf>r</inf> , saturation , <italic>t,</italic> Δ<italic>t</italic> , elapsed time , <italic>u</italic> , pore water pressure , <italic>w</italic> , water content , <italic>w</italic> <inf>L</inf> , liquid limit , <italic>w</italic> <inf>p</inf> , plastic limit , <italic>w</italic> <inf>opt</inf> , optimum water content , Δ<italic>e</italic> , wetting-induced variation of void ratio , <italic>δ</italic> <inf>ef</inf> , free swelling ratio , <italic>δ</italic> <inf>cp</inf> , swelling ratio with load 50 kPa , <italic>ε</italic> <inf><italic>a</italic></inf> , axial strain in triaxial test and unconfined compression test , <italic>ρ</italic> , density , <italic>ρ</italic> <inf>dmax</inf> , maximum dry density , <italic>σ</italic> <inf>3</inf> , cell pressure , <italic>σ'</italic> <inf>v</inf> , vertical effective stress , <italic>ϕ</italic>'<inf>cu</inf> , effective internal friction angle , <italic>ϕ</italic> <inf>r</inf> , residual internal friction angle
Engineering in Mercia mudstone
| TIBKAT | 2001
Effect of Shearing Speed on Residual Shear Strength of Natural Soil Obtained from Mudstone
| British Library Conference Proceedings | 2011
The development of a residual soil profile from a mudstone in a temperate climate
| Online Contents | 2004