scholarly journals Case Study in The Northern Cape (Loopeng Area), South Africa, Confirming Occurrence of a Collapsible Soil Structure in Transported Soils

2021 ◽  
Author(s):  
Frederik Daniël Jacobus Stapelberg
Keyword(s):  
South Africa ◽  
Soil Profile ◽  
Soil Structure ◽  
Soil Conditions ◽  
Collapsible Soil ◽  
Local Conditions ◽  
Geotechnical Characteristics ◽  
Structure Description ◽  
Northern Cape

Abstract Testing was performed on transported soils belonging to recently deposited sandy-silty soil deposits occurring in the Northern Cape Province, South Africa in order to determine the occurrence and order of magnitude of a collapsing sand soil structure. Various empirical geotechnical characteristics including: in situ soil profile structure description, particle grading curve and clay content, soil classification, soil density and void ratio were compared to collapse potential values determined with oedometer testing in order to judge the success with which the empirical characteristics can be utilized to predict the occurrence of a collapsible soil structure.From the results it is clear that a collapsing sand structure exists in the transported soils and the empirical descriptors mostly correctly indicate the occurrence or the particular soil structure when compared to previous studies on collapsing sands. The one descriptor which reflects a relatively poor correction between the descriptor and the soil structure (in situ soil profile structure description) is considered to be a poor indicator of the collapsible soil structure due to erroneous or poor in situ soil structure observations resulting from unfavourable local conditions namely dry, dusty soil conditions and very brief intact standup time of test pit side walls.

scholarly journals Microstratigraphic evidence of in situ fire in the Acheulean strata of Wonderwerk Cave, Northern Cape province, South Africa

2012 ◽  
Vol 109 (20) ◽  
pp. E1215-E1220 ◽  
Author(s):  
F. Berna ◽  
P. Goldberg ◽  
L. K. Horwitz ◽  
J. Brink ◽  
S. Holt ◽  
...  
Keyword(s):  
South Africa ◽  
Northern Cape

scholarly journals The Rehabilitation of Structures on the National Route 10 Section 12 between Upington Km 0.0 and Nakop Km134.17

2018 ◽  
Vol 199 ◽  
pp. 10003
Author(s):  
Tiago Massingue ◽  
Bennie Zietsman
Keyword(s):  
South Africa ◽  
Compressive Strength ◽  
Bridge Management ◽  
Bridge Management System ◽  
Existing Structures ◽  
Floor Slabs ◽  
Deck Slabs ◽  
Northern Cape ◽  
Materials Used

National Route 10 Section 12 is situated between Upington and Nakop at the border between South Africa and Namibia in the Northern Cape Province. As part of SANRAL’s Bridge Management System, three bridges and twenty four major in-situ cast culverts were identified to be in need of rehabilitation and/or strengthening. This paper details the condition of the existing structures as well as the methods and materials used to repair and strengthen the structures to be in a safe and serviceable condition. Due to the harsh environmental conditions, as well as the remoteness of the structures, the methods and materials for repair had to be carefully considered. In this regard, special reference is made to the use of carbon fibre strips to increase the bearing capacity of the bridgeand culvert deck slabs. The method for the strengthening of the floor slabs and internal walls of a number of culverts, for which the compressive strength of the existing concrete was found to be in the order of 1.0 MPa, is also discussed.

A geometallurgical characterization study of the Crystalkop Reef at the Great Noligwa Mine, Klerksdorp Goldfield, South Africa

2017 ◽  
Vol 120 (3) ◽  
pp. 303-322
Author(s):  
D. Pienaar ◽  
B.M. Guy ◽  
C. Pienaar ◽  
K.S. Viljoen
Keyword(s):  
South Africa ◽  
Treatment Plant ◽  
Processing Parameters ◽  
Processing Plant ◽  
Small Contribution ◽  
Gold Cyanide ◽  
Three Samples ◽  
Characterization Study ◽  
Different Sources

Abstract Mineralogical and textural variability of ores from different sources commonly leads to processing inefficiencies, particularly when a processing plant is designed to treat ore from a single source (i.e. ore of a relatively uniform composition). The bulk of the Witwatersrand ore in the Klerksdorp goldfield, processed at the AngloGold Ashanti Great Noligwa treatment plant, is derived from the Vaal Reef (>90%), with a comparatively small contribution obtained from the Crystalkop Reef (or C-Reef). Despite the uneven contribution, it is of critical importance to ensure that the processing parameters are optimized for the treatment of both the Vaal and C-Reefs. This paper serves to document the results of a geometallurgical study of the C-Reef at the Great Noligwa gold mine in the Klerksdorp goldfield of South Africa, with the primary aim of assessing the suitability of the processing parameters that are in use at the Great Noligwa plant. The paper also draws comparisons between the C-Reef and the Vaal Reef A-facies (Vaal Reef) and attempts to explain minor differences in the recovery of gold and uranium from these two sources. Three samples of the C-Reef were collected in-situ from the underground operations at Great Noligwa mine for mineralogical analyses and metallurgical tests. Laboratory-scale leach tests for gold (cyanide) and uranium (sulphuric acid) were carried out using dissolution conditions similar to that in use at the Great Noligwa plant, followed by further diagnostic leaching in the case of gold. The gold in the ore was found to be readily leachable with recoveries ranging from 95% to 97% (as opposed to 89% to 93% for the Vaal Reef). Additional recoveries were achieved in the presence of excess cyanide (96% to 98%). The recovery of uranium varied between 72% and 76% (as opposed to 30% to 64% for the Vaal Reef), which is substantially higher than predicted, given the amount of brannerite in the ore, which is generally regarded as refractory. Thus, the higher uranium recoveries from the C-Reef imply that a proportion of the uranium was recovered by the partial dissolution of brannerite. As the Vaal Reef contain high amounts of chlorite (3% to 8%), which is an important acid consumer, it is considered likely that this could have reduced the effectiveness of the H2SO4 leach in the case of the ore of the Vaal Reef. Since the gold and uranium recoveries from the C-Reef were higher than the recoveries from the Vaal Reef, the results demonstrate that the processing parameters used for treatment of the Vaal Reef are equally suited to the treatment of the C-Reef. Moreover, small processing modifications, such as increased milling and leach retention times, may well increase the recovery of gold (particularly when e.g. coarse gold, or unexposed gold, is present).

scholarly journals Effect of Earthing Enhancing Compound (EEC) on Improving Tower Footing Resistance of a 500 kV Tower in a Rocky Area

2021 ◽  
Vol 11 (12) ◽  
pp. 5623
Author(s):  
Nur Alia Farina Mohd Nasir ◽  
Mohd Zainal Abidin Ab Kadir ◽  
Miszaina Osman ◽  
Muhamad Safwan Abd Rahman ◽  
Ungku Anisa Ungku Amirulddin ◽  
...  
Keyword(s):  
Electromagnetic Field ◽  
Comparative Analysis ◽  
Transmission Line ◽  
Structure Analysis ◽  
Current Distribution ◽  
Soil Profile ◽  
Soil Structure ◽  
Soil Resistivity ◽  
Transmission Towers ◽  
Rocky Soil

This paper presents a comparative analysis of different earthing designs’ performances, with particular interest on the use of earthing enhancing compound (EEC) for a selected earthing design of 500 kV transmission towers in a rocky soil, using the SESCAD tool of the Current distribution, electromagnetic field grounding and soil structure analysis (CDEGS) software. The simulation included the interpretation of soil profile and comparison between designs A, B and C, which are currently used for the 500 kV tower footing resistance (TFR) improvement. Results showed each design had reduced the TFR by 66%, 54.7% and 63.2% for the towers T42, T48 and T50, respectively. In some cases, further improvement of TFR is required, especially in the rocky area where the soil resistivity (SR) value is of more than 500 Ω⋅m. In this case, EEC was used in Design C, encasing both the vertical and horizontal electrodes, and it reduced the TFR further by 16% to 20%. The characteristics of the soil and earthing arrangement design play an important role in achieving a low TFR value, which is directly proportional to the backflashover occurrence and thus to the transmission line performance.

scholarly journals Global earthworm distribution and activity windows based on soil hydromechanical constraints

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Siul A. Ruiz ◽  
Samuel Bickel ◽  
Dani Or
Keyword(s):  
Soil Structure ◽  
Mechanistic Model ◽  
Biophysical Model ◽  
Ecosystem Functions ◽  
Soil Conditions ◽  
Agricultural Systems ◽  
Occurrence Patterns ◽  
Additional Constraints ◽  
Earthworm Activity ◽  
Good Agreement

AbstractEarthworm activity modifies soil structure and promotes important hydrological ecosystem functions for agricultural systems. Earthworms use their flexible hydroskeleton to burrow and expand biopores. Hence, their activity is constrained by soil hydromechanical conditions that permit deformation at earthworm’s maximal hydroskeletal pressure (≈200kPa). A mechanistic biophysical model is developed here to link the biomechanical limits of earthworm burrowing with soil moisture and texture to predict soil conditions that permit bioturbation across biomes. We include additional constraints that exclude earthworm activity such as freezing temperatures, low soil pH, and high sand content to develop the first predictive global map of earthworm habitats in good agreement with observed earthworm occurrence patterns. Earthworm activity is strongly constrained by seasonal dynamics that vary across latitudes largely due to soil hydromechanical status. The mechanistic model delineates the potential for earthworm migration via connectivity of hospitable sites and highlights regions sensitive to climate.

Micromorphology of soil structure - Description, quantification, application

Soil Research ◽  
1991 ◽  
Vol 29 (6) ◽  
pp. 777 ◽  
Author(s):  
AJ Ringrose-Voase
Keyword(s):  
Soil Structure ◽  
Pore Space ◽  
Structural Parameters ◽  
Thin Sections ◽  
Physical Measurements ◽  
Undisturbed Samples ◽  
Structure Description ◽  
Management Techniques ◽  
Pore Types ◽  
Soil Behaviour

Micromorphological observation can provide insights into soil structure and aid interpretation of soil behaviour. Undisturbed samples are taken in the field and impregnated. They are used to prepare thin sections or images of the macropore structure using fluorescent photography. Sections can also be obtained at macro, meso and submicroscopic scales. The various elements of soil structure observed micromorphologically can be classified into pore space, physical, distribution and orientation fabrics, and associated structures. Examples of the importance of features in each category are given. Image analysis, especially when computerized, provides a way of parameterizing micromorphological observations. To date it has been used primarily on images of macropore space at the meso and microscopic scales. Such images can be digitized and segmented to show pore space and solid. The pore space can be allocated to pore types. This aids the estimation of 3-D parameters from I-D and 2-D measurements made on the image using stereology. Various ways of using structural parameters to compare structures are discussed. Applications for micromorphological observations, especially when quantitative, include comparison of structures formed by different management techniques. Structural measurements can aid interpretation of soil behaviour as described by physical measurements. They also have a role in estimating the representative elementary volume, on which physical measurements should be made, and in calibrating field estimates of soil structure.

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