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Soils, rocks, and groundwater
Published in Rodrigo Salgado, The Engineering of Foundations, Slopes and Retaining Structures, 2022
Carbonaceous rocks, such as limestone and dolomite, are sedimentary rocks resulting most commonly from the diagenesis of calcareous soils and sometimes from precipitation of calcite or dolomite from solution. These rocks are extremely soluble rocks, which frequently lead to the formation of karst. Karst is a term originally used to describe the landscape characteristic of the Karst region of Yugoslavia (Goodman 1992). In the United States, karst is found, for example, in southern Indiana, Kentucky, and parts of Florida. Karstic terrain presents challenges to the foundation engineer, particularly when it is in its advanced stage, when it usually contains underground cavities that can sometimes collapse, forming sinkholes. The process of site exploration in such terrains is very important, as it is desirable to learn as much as possible about the likelihood of existence of caverns and cavities and to assess the likelihood that their roof will not collapse. Another feature of karstic terrain is that the residual soil overlying rock can present very marked variations in elevation, with pinnacles of rock alternating with cavities. Figure 3.5 shows a typical mature karst terrain, where a cavity has collapsed.
A probabilistic approach to assess the risk of liner instability when tunnelling through karst geology using geotechnical baseline reports
Published in Daniele Peila, Giulia Viggiani, Tarcisio Celestino, Tunnels and Underground Cities: Engineering and Innovation meet Archaeology, Architecture and Art, 2020
K. Yau, C. Paraskevopoulou, S. Konstantis
Limestone is a good medium for tunnelling but when karstified it can deteriorate the construction process. Karst can be described as a type of landscape that occurs from the dissolution of highly soluble rocks, such as limestone and gypsum by water movement. This process forms extensive water networks made up of cavities and discontinuities that induce secondary porosity (fractures) and tertiary porosity (conduits). The latter contributes to spatial uncertainty as the formation of pathways is both a function of rock dissolution rate and the geological structure. In addition, karst systems continually evolve over time because of the feedback loop between the dissolution and material property. Continual flow can erode pathways and wash out fines, leading to material degradation (Marinos, 2001).
Studying the effects of gypsum karst cavities in tunneling
Published in Daniele Peila, Giulia Viggiani, Tarcisio Celestino, Tunnels and Underground Cities: Engineering and Innovation meet Archaeology, Architecture and Art, 2020
Karsts are topographies formed through the dissolution of the bedrock caused by surface or groundwater. Sinkholes, caves, large springs, dry valleys and sinking streams are typical features of karst landscapes. These features cannot be easily detected at the surface, but they generally occur within certain bedrock-geologic formations such as Carbonate rocks (limestone, marble, dolomite) and evaporate rocks (gypsum and rock salts) (Veni, 2001; Williams, 2008). Gypsum is one of the most soluble common rocks, for instance when gypsum is subjected to water flow, it dissolves 100 times faster than limestone. Even though the karst features that form within gypsum are typically the same as the ones that form within limestone or dolomite, the main difference is that those features form more rapidly within gypsum, i.e. within a matter of weeks or years. This higher solubility of gypsum, as well as, the fact that voids within gypsum layers could occur at any depth, poses a threat to infrastructure development. Voids within gypsum formation are openings where groundwater can be stored, and if connected provide pathways for groundwater flow. In Abu Dhabi, the existence of the presence of gypsum that occurs within the tertiary bedrock, as persistent quasi-horizontal bands, at different depths, poses a threat to construction. In fact, the dissolution of gypsum is also a cause for cavities that can be found within this formation in greater Abu Dhabi (Figure 1 and 2).
Improvement of karst soil nutrients by arbuscular mycorrhizal fungi through promoting nutrient release from the litter
Published in International Journal of Phytoremediation, 2021
Qiyu Tan, Jianpeng Si, Yuejun He, Ying Yang, Kaiping Shen, Tingting Xia, Liling Kang, Zhengyuan Fang, Bangli Wu, Yun Guo, Xu Han
Karst topography, a special landscape shaped by the dissolution of carbonate rocks (e.g., limestone or dolomite), accounts for approximately 20% of the land area (Jiang et al. 2014). The karst terrain of south-western China covers a land of 0.51 million km2 and suffers from serious rocky desertification (Li et al. 2016). Karst habitat is characterized by soil layer with severe soil erosion and nutrients deficiency (Zhang et al. 2015). In this nutrient-deficient habitat, litter decomposition represents an important ecological process controlling the nutrients availability and carbon (C) balance (Ge et al. 2013). The return of nutrients through plant litter decomposition may be a crucial mechanism to support high diversity in the karst area (Zhu et al. 2021).
Basin-wide hydrological system assessment under climate change scenarios through conceptual modelling
Published in International Journal of Digital Earth, 2020
Cenk Donmez, Suha Berberoglu, Ahmet Cilek, Peter Krause
Even though, the model performance was satisfying in our study, consisting of such uncertainties is a main problem for such modelling studies. This is due to unaccountable water deviations in karst regions. Those regions such as Goksu Watershed generate significant amount of runoff. Karst topography usually forms in regions of plentiful rainfall where bedrock consists of carbonate-rich rock, such as limestone, gypsum, or dolomite, that is easily dissolved. Surface streams are usually absent from karst topography. Since %30 of the region is consisted of the karst system unmeasured runoff are defined that might have negative and unaccountable deviations, even though an ideal calibration process is greatly facilitated in the study. In this case, the model application represents different discharge components which have improved insight into the hydrological dynamics of the region. The model results consisted that the basin has reasonable amount of RG1 and RG2 that can be helpful to express the water allocation in a karstic system. Moreover, the hydrograph suggested higher overland flow than expected. It contributes about 32% to the streamflow. This contribution of overland flow is attributed to intense rainfall during the spring that might cause the saturation of soil out of the karstic areas in the region.
Efficiency of local minima and GLM techniques in sinkhole extraction from a LiDAR-based terrain model
Published in International Journal of Digital Earth, 2019
Péter Enyedi, Melinda Pap, Zoltán Kovács, László Takács-Szilágyi, Szilárd Szabó
Field survey, topographic maps and aerial images represent the most important database for karst-related research and monitoring (e.g. Bárány-Kevei and Mezősi 1993; Kaufmann and Quinif 2002). Beside the commonly used remote sensing technics and GIS applications, digital elevation models (DTMs) represent a great step forward in the mapping of surface land karst forms. Satellite derived digital surface models (SRTM, ASTER) have also provided important data in the identification of macro scale land karst forms since 2003, but their geometric resolution can be inappropriate for detailed analyses (de Carvalho et al. 2014; Theilen-Willige et al. 2014). The development of aerial remote sensing technologies including the application of active airborne sensors was a particularly important step in opening new dimensions in fast and accurate spatial data production for the topographic mapping of large areas (Bekő et al. 2016; Szabó et al. 2017). Airborne laser scanning technology provides accurate spatial topographical data for large-scale analyses (Kraus and Pfeifer 2002; Mücke et al. 2013). The most relevant feature of the LiDAR technology allows us to acquire spatial information under densely covered areas due to multiple returns of laser beam; i.e. this technique is able to produce DTMs while other approaches (e.g. stereo photogrammetry) provide only digital surface models (DSMs) (Hodgson and Bresnahan 2004; Zlinszky et al. 2015). Thus, karst morphology analysis, considering that vegetation covers landforms, can only be efficient with LiDAR-based DTMs.