GEOTECHNICAL INVESTIGATION OF THE PROPOSED IFE DAM SITE AT KAJOLA VILLAGE, ILE-IFE, SOUTHWESTERN NIGERIA

Geological and geophysical investigations were conducted to assess the competence and structural integrity of the foundation site of the proposed Ife-dam at Kajola Village, Ile-Ife, Southwestern Nigeria. Geological investigation along the two (2) proposed dam axes revealed that the overburden material is loose to dense with angular shearing resistance (ɸ) of 27o to 41o. The soils are predominantly elastic silts; cohesive with considerable strength and stability. Geophysical investigation involving the Schlumberger Vertical Electrical Sounding delineated four (4) lithologies namely: topsoil with resistivity of 69 – 558 Ωm and thickness between 1.5 and 4.0 m; weathered sandy layer with resistivity from 123 – 586 Ωm and thickness between 6.5 and 20.4 m; partially weathered/ fractured basement with resistivity from 60 – 220 Ωm and thickness between 6.5 and 14.0 m; and the fresh basement rock with resistivity from 1337 – 10683 Ωm. There are indications of fractures at a depth of 32 m beneath Axis B extending to Axis A at a depth of 35 m. The subsurface materials are suitable to host a dam. Axis B is more appropriate for the dam axis, although the fracture zone should be factored into the design of the dam to prevent water seepage.

GEOSPATIAL APPROACH FOR GEOLOGICAL INVESTIGATION AT DISTRICT OF MERSING

Effective geological information evaluation is essential for accurate site characterization. A major concern in geological mapping is to locate the accurate location of the geological information. The geoinformation approach such as precise GPS surveying and UAV mapping could be integrated with other geospatial information to augment the geological information. This research aims to integrate the geoinformation approach into geological structure mapping. To achieve the overall purpose of the study, the objective identified was the establishment of a high-precision control point by using Precise GPS measurement in the study area. Therefore, the establishment of GPS data observations involves the establishment of primary networks and several GPS controls points within the study area. Subsequently, the GPS positioning has been processed to produce a topographic information map and to support the collection of geological data in the study area. It is hoped that the integration of the geoinformation approach has been provided a significant increase in geological information at the district of Mersing.

Research on the Controlling Effect of NPR Cables for Anti-Dip Slope Based on the Numerical Simulation

As the scale and depth of mines increase, large deformations of high-steep slopes progressively become prominent. Compared with the ordinary cables, negative Poisson’s ratio (NPR) cables can provide a constant resistance force and high deformation inhibition during slope deformation, avoiding the occurrence of slope instability hazards. Consequently, the control effects on the toppling failures of slopes were necessary to be researched. Changshanhao open-pit gold mine was taken as an example; based on the field geological investigation and rock mechanics testing, a three-dimensional engineering geological model of open-pit mine was constructed. Subsequently, the stability of open pit in current situation and final boundary situation was estimated with FLAC3D software, for the potential slope vulnerable areas to be comprehensively identified. Finally, the control effects of ordinary cables and NPR cables on the instable W13 slope section were compared and studied through FLAC3D simulations, and the reinforcement effects of NPR cable on the anti-dip slope were proved as significant; meanwhile, the corresponding reinforcement methods in the failure mine areas were proposed, laying a reference for the instability failure control and reinforcement of similar anti-dip slopes.

Evaluation of potential liquefaction based on Cone Penetration Test (CPT) data

An earthquake can inflict a liquefaction hazards which can damage buildings and infrastructure. Furthermore, earthquakes are difficult to predict when and where earthquakes will occur and happen suddenly without being preceded by signs. Therefore, we must do a geological investigation before building a construction to evaluate the potential liquefaction in that area. Evaluation of the potential liquefaction using Cone Penetration Test (CPT) is one method can be used because repeatable, provided a continuous profile, and economic. This method needs peak ground acceleration (amax) value at an interval of 0.1 g to 0.6 g and earthquake magnitude of 6.2 scale richter. Based on the results of the research was obtained in this research area, there were potential liquefactions when the peak ground acceleration (amax) value was above 0.3 g.

Investigation of Rawa Dano Volcanic Deposits and Its Paleotopography Using Ground-Penetrating Radar

The detailed mechanisms of volcanic eruptions happened around Rawa Dano, Banten, Indonesia, remain undiscovered. One of the key features to this geological event is the presence of a 13.7 km × 6.5 km caldera-like morphology in the middle of Banten tuff deposits. Surface geological investigation in the area indicates that the eruptions are massive and occurred in several periods. Low-frequency ground-penetrating radar (GPR) signals are used as an aid to identify the unexposed part of the deposits in this volcanological study. Common-offset GPR surveys were carried out along three measurement lines traversing over the deposit outcrops. An outcrop which is exposed after sand mining activities at one of the survey locations shows dipping interfaces between the upper pyroclastic flow deposits, pumice-rich deposits, paleosol, and the lower pyroclastic fall deposits. These stratigraphic contacts are detected as well under the surface which are clearly recognizable in radar images. The GPR cross-section also shows some other reflections due to different deposit types. The overall results of the GPR profiles give the idea about the thickness of each type of volcanic deposits and the paleotopography in the surrounding area.

Geochemistry and mineralogy of the Truc Thon Clay, Hai Duong Province, North Vietnam: implication for paleoclimatic and provenance analysis

During the Miocene-Pleistocene, generally sub-tropical to tropical warm and humid paleoclimate prevailed in Southeast Asia with a gradual cooling trend. The Truc Thon clay (TTC) mine presents interesting outcrops for sedimentological and provenance analysis. The present study uses results of geological investigation in 16 outcrops and wells at the clay mine Truc Thon. The TTC has lens-shaped geometry, filled with two clay bodies, including grey-white clay and multicolor clay. Bulk mineralogy indicates the predominance of quartz and a relatively high amount of pyrophyllite. Clay mineralogy shows the presence of main kaolinite, followed by illite and mixed-layer illite-smectite. These may interpret a warm, humid paleoclimatic condition in the source areas. Illite may be inherited from basement rocks. The bulk rock geochemistry supports intense chemical weathering with the Chemical Index of Alteration (CIA) in the TTC ranged ca. 80.6-98 (average = 90.4). In combination with the geochemical proxies and the mineralogical composition of the TTC, the chemical weathering intensity indicated warm/hot, semi-humid/humid tropical paleoclimate in the source area. A combination of mineralogical and geochemical analyses with regional geological features show that the Hon Gai Triassic rocks are the main source for the TTC. Source materials are originally related to silicic rocks of granitic-granodioritic composition. Paleoclimatic conditions favored intense chemical weathering of the Hon Gai Triassic rocks and surrounding rocks, creating a ceramic mine of great industrial value.

Detailed investigation algorithm for hydrocarbons deposits exploration in terms of the Shebelynske gas-condensate field

In order to elaborate the neotectonic structure and improve the searching algorithm of new hydrocarbon traps at prospective areas, detailed airspace geological investigation has been carried out. For this study, the selected cross-section Dniprovsko-Donetska depression is the regional seismic profile Lozova-Shebelinka-Staropokrovka within the Shebelinska structure zone.In particular, the investigations consisted of structural and geomorphological analysis, analysis of the hourly seismic profile Lozovaya-Shebelinka-Staropokrovka and analysis of thermal anomalies and structural interpretation by using satellite images. This approach allowed to explore the Shebelinska structure zone and the East-Shebelinska depression for hydrocarbon traps feature properties detecting in Paleozoic sediments.Based on the results of the initial data processing, we established that Paleozoic complex cannot create hydrocarbon deposits, both due to low reservoir properties and due to insufficiently studied structure. Neotectonically, the Shebelinskaya structure looks like a dome-shaped uplift. This uplift is divided by a ravine-gully network into neotectonic blocks. Productive wells are located within the most active blocks.