Detection of Cracks in Clay Soil Using Quasi-3D Electrical Resistivity Tomography Method: Numerical and Experimental Study

Soil cracks affect the geotechnical characteristics of clay soils frequently used in engineered earth structures. In this work, numerical simulation and laboratory tests using Wenner- Schlumberger array of Electrical Resistivity Tomography (ERT) method are adopted to detect soil cracks in compacted clay soil. 3D numerical simulation showed that air-filled cracks have an anomalous high resistivity signature that can be differentiated from the background due to the high resistivity contrast between cracks and the surrounding soil. Depth, geometry, and extension of the simulated cracks are reasonably indicated. At the laboratory scale, quasi-3D ERT experiment was conducted. The results showed that soil resistivity is significantly affected by an artificially introduced crack as the crack forms a barrier that disturbs the flow of electricity in the soil. Similarly, depth, geometry, and extension of the crack are detected. Both numerical and experimental findings demonstrated that ERT method can effectively be used to identify cracking in clay soils. It is suggested that ERT, as a non invasive method, can be adopted with other traditional geotechnical methods for detecting cracks in clay soils.

Geotechnical Characteristics of Benin Formation, Owerri Imo State, Nigeria

A good road network consists of a constant stretch of asphalt laid down for a smooth ride. The spot in the smooth ride on the pavement is commonly referred to as "pavement failure." Soil type, load bearing capacity of materials, zone of vulnerability, resistance to permeation, compressibility, shrinkage limit, and other details are frequently required in order to construct a very good and solid foundation for the planned bridge site. In Nigeria, numerous factors contribute to the failure of road construction projects. They are primarily insufficient research on subgrade and other pavement materials (sub-base and base courses) prior to the start of road projects; flawed engineering, including a poor drainage system and supervision throughout road construction; and shoddy workmanship that was superimposed with asphaltic concrete to improve strength. Within the Niger Delta basin, the study area is located between latitude 5.485°N and longitude 7.035°E. The Benin Formation underpins the study area. It is composed primarily of friable sands, conglomerates, very coarse sandstone, and isolated gravel units, as well as intercalation of Pliocene to Miocene shale/clay lenses. Natural Moisture Content (NMC), Linear Shrinkage (LS), Particle Size Distribution, and California Bearing Ratio were among the laboratory tests performed on samples collected at failed and stable sections of some selected road segments (CBR). When compared to the stable sections, the NMC along the failed sections was on the high side (ranging from 13.11 percent to 26.89 percent) (ranging from 11.11 percent to 16.40 percent). The majority of the tested soils passed the 0.075mm sieve with a percentage greater than the Federal Ministry of Works and Housing's maximum of 35% for subgrade materials. The maximum dry density (MDD) for the samples at failed and stable sections was 1550 kg/m3 to 1860 kg/m3; 1650 kg/m3 to 1980 kg/m3; and the Optimum Moisture Content (OMC) was 8.30% to 20.30%. The soaked CBR values ranged from 2 to 17 percent, while the unsoaked values ranged from 4 to 25 percent.

A State-of-the-Art Review on Suitability of Granite Dust as a Sustainable Additive for Geotechnical Applications

The increase in infrastructure requirement drives people to use all types of soils, including poor soils. These poor soils, which are weak at construction, must be improved using different techniques. The extinction of natural resources and the increase in cost of available materials require us to think of alternate resources. The usage of industry by-products and related methods for improving the properties of different soils has been studied for several years. Granite dust is an industrial by-product originating from the primary crushing of aggregates. The production of huge quantities of granite dust in the industry causes severe problems from the handling to the disposal stage. Accordingly, in the civil engineering field, the massive utilization of granite dust has been proposed for various applications to resolve these issues. In this context, the present review provides precise and valuable content on granite dust characterization, its effect as a stabilizer on the behavior of different soils, and its interaction mechanisms. The efficacy of the granite dust in replacing sand in concrete is explored followed by its ability to improve the geotechnical characteristics of clays of varying plasticity are explored. The review is even extended to study the effect of binary stabilization on clays with granite dust in the presence of calcium-based binders. The practical limitations encountered and its efficiency over other stabilizers are also assessed. This review is further extended to analyze the effect of the granite dust dosage for various field applications.

Characteristics of Carbonate Rocks and Environmental Conditions of Some Caves, Northern Iraq

Six caves were studied in north Iraq, which is the Beeston and Shanidar in Erbil, Garston, Swaratuka, and Ain Ishky in Duhok Governorate, Al-Naqut in Nineveh Governorate. All these caves are located within geological formations of carbonate rocks, limestone, and dolostone. Geotechnical and geometrical measurements were made for these caves, and rocks were sampled from different areas inside and outside the caves. The slake durability of the rocks was measured and thin sections were made, in addition to measuring the percentage of insoluble residues and analyzing the mineral constituents of the collected samples by using X-ray diffraction. By reviewing the geotechnical characteristics and environmental conditions, the Beeston Cave was found to be the oldest of the caves studied because its size is greater than that of the other caves and its rocks have better geotechnical characteristics than the other caves, which means that the time required for it to form is longer. The Al-Naqut Cave was also found to be the newest among these six caves because, in addition to its small size, it has the lowest durability value after the Shanidar Cave and has the lowest value of compressive strength.

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

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.

ENGINEERING GEOLOGICAL AND GEOTECHNICAL CHARACTERISTICS OF LANDSLIDE IN GORNJI HRGOVI, MUNICIPALITY OF SREBRENIK

Natural disasters during May 2014 caused a flood of water outside the unregulated bed of the river Tinja in the local area of Gornji Hrgovi. The flood effect affected the undermining and destruction of the foot part of the slope, reactivation and regressive development of the landslide, which was manifested by further secondary "breaking" of the sliding body towards the hypsometrically top part of the slope and intersection of the primary water pipeline. Gravitational displacement of the colluvial material resulted in significant degradation of the agricultural land surface in the central part of the unstable slope, while in the accumulation zone the accumulated slide mass destroyed the earth road communication. Based on the conducted geotechnical researches, determined engineering-geological and hydrogeological composition and properties of the terrain, the zoning of the terrain according to the degree of stability was performed, important recommendations and conditions of the landslide remediation method were presented.