Geological,geophysical and Geotechnical Investigations

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Geophysical and Geotechnical Investigations of a proposed Site for Afijio Local Government Stadium Ilora, Southwestern Nigeria.

Geophysical and Geotechnical Investigations of a proposed Site for Afijio Local Government Stadium Ilora, Southwestern Nigeria.

Abstract- Stadium disasters due to inappropriate multiple engineering/geological errors have been part of history of the world necessitating pre construction site investigation using geotechnical and geophysical evaluation of a proposed Site for Afijio Local Government Stadium Ilora, Southwestern Nigeria. gGeotechnical aspect of this research involved, diging of three trial pits and seven samples were taken per pit at interval of 0.5m. The samples were taken to the laboratory for grain size analysis and consistency limits determination following the standards specified by ASTM D6913-04. Furthermore, five points on the proposed site were occupied employing Schlumberger electrode array, with a maximum current electrode spacing (AB/2) of 100m. The data obtained were interpreted using partial curve matching technique and RESIST software. Results of the geotechnical investigation revealed that the soil samples from the proposed site have plastic limit that ranged from 50 – 95 (av. 69), liquid limit from 5 – 25 (av. 15.43) while the plasticity index ranged between 30 and 70 (av.53.57). The soil samples from the proposed site are in the intermediate to high plasticity class, poorly graded and with high percentage finer passing 0.075 mm (av. 96.12%).. Electrical resistivity survey of the study area revealed three geoelectric curves (H, QH and Q) indicative of the preponderance of the combined weathered and fractured layer (unconfined) aquifers system. Five different subsurface lithologic sequences namely; lateritic topsoil, sandy clay, weathered basement, fractured basement and fresh basement were delineated with overburden thickness ranging from 1 to 60m. Geo-electric layers of the VES stations revealed generally, partially weathered/fractured subsurface Geotechnical assessment revealed that, the average percentage of the finer exceeded 35% approved maximum standard for a foundation material and also the site being underlain by poorly graded soil that did not meet engineering specification for foundation render the site unsuitable such massive structure while the electrical resistivity survey revealed partially weathered/fractured terrain which further confirmed its unsuitability. Except, there is constrain of space, if this site must be used, further investigation must be done using other geotechnical approaches to better understand engineering strength characteristics of the underlying soil for well engineered foundation design to ensuring safety of the proposed structure.

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Geophysical and Geotechnical Investigations of a Landslide in Kekem Area, Western Cameroon

Geophysical and Geotechnical Investigations of a Landslide in Kekem Area, Western Cameroon

compressible. The causes of the sliding of Kekem are varied: they are internal and external. The internal causes are the characteristics specific to the slope. It is about lithology, the structural disposition and the value of the angle of the slope. The external factors as for them de- stabilize by their actions the internal structures of the formations of the slope and cause their movement. It is of the climate, basal undercutting and the anthropogenic action. Water is the worsening factor of the landslides; it is the engine and the catalyst of the majority of the ac- tions of the other factors. Under the action of water, the mechanical deformation of clays which form the domi- nant fraction of the geological units of the slope is the main cause. The geological formations rich in clays are generally impermeable with water, however, the struc- tural disposition and the human intervention amplified the density of the zones of weakness which allowed an in-depth imbibitions. When all the factors are present, only gravity is required to provoke the sliding. This ac- tion of gravity was facilitated by basal undercutting by the river Ngoum at the foot of the hill.

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Geological And Geotechnical Investigations Of Axum Dam Site, Tigray, Northern Ethiopia

Geological And Geotechnical Investigations Of Axum Dam Site, Tigray, Northern Ethiopia

Abstract: Geological and geotechnical study was conducted in concrete gravity dam which is planned to be constructed in the Maychew River 40 km south of Axum town for the purpose of water supply for the town. The objectives of this research were: to map geology of the area, to characterize geological defects within and around dam site, to evaluate the water tightness of the dam site, and to determine the bearing capacity of the dam foundation. The research involved: review of different literatures, lithological and structural mapping, characterizing rock masses by using different rock mass classification methods, interpretation of subsurface data (geophysical, core drilled data, test pit data etc.). Results of the study indicate that the area is underlain by Quaternary sediments, metasedimentary and metavolcanic rocks. The Quaternary sediments are characterized by low permeability, low plasticity and are poorly graded nature. Metasedimentary rocks are found covering the right abutment of the dam whereas at reservoir area it is found intercalating with metavolcanic rocks. These rocks are moderately jointed and sheared with faulting and folding noticed; due to these they have a relatively high permeability. Metavolcanic rocks which are found covering the left abutment are strong, less permeable and fractured. Most of discontinuities such as fractures, bedding and foliation in the study area are oriented E-W, NNW-SSE and NNE-SSW. The VES, tomography and drilled core result revealed that the potential problems (seepage/leakage) could occur due to presence of faults, joints, karstified black limestone, lithological variations, groundwater depth and topography at right abutment. Differential settlements may also occur because empirically estimated moduli of deformation (Ed) of rock masses indicate that for right abutment much less than left abutment and different geological defects across the dam axis. To minimize these problems contact grouting and consolidation grouting are recommended as mitigation measurements.

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Integration of Geophysical and Geotechnical Soil Characteristics for Local Site Seismic Design in Georgia

Integration of Geophysical and Geotechnical Soil Characteristics for Local Site Seismic Design in Georgia

In the presented manuscript one engineering project location was selected as the case study. For this location high rise building construction was planned (more than 12 floors). For this location complex survey was applied such as geological and geotechnical investigations, geophysical survey (seismic profiling and downhole test in wells), seismic hazard assessment, site-dependent seismic ha- zard assessment. All needed data for probabilistic seismic hazard assessment such as active faults, seismic source zones, seismic catalogues and seismic para- meters, ground motion attenuation models, etc. were collected and reviewed. At the end all investigations were merged and final conclusions were done.

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Integrated Geological, Geophysical and Geotechnical Assessmentof Building Failurein Lagos;a Case Studyof Ogudu Lagos South Western Nigeria

Integrated Geological, Geophysical and Geotechnical Assessmentof Building Failurein Lagos;a Case Studyof Ogudu Lagos South Western Nigeria

Early detection and discovery of the causes of building collapse via the mandatory, periodic or conditional structural integrity assessment go a long way in preventing incessant building collapse and eliminate the attendant loss of life and other properties.Geophysical and geotechnical investigations have been carried out to probe the subsoil conditions of abuilding at risk in Ogudu area of Lagos in order to establish its engineering characteristics and the appropriate foundation suitable for the site. The occurrence of low resistivity, incompetent peat and organic clay within the depth range of 1 to 9 m implies that shallow foundation will was not be suitable for thebuilding, the imposed load resulted to differential settlement of the building. From the subsoil strata revealed in the completed borehole, considering the storey building and the subsoil/water conditions as revealed in the completed

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Structure and nature of the Palaeozoic basement based on magnetic, gravimetric and seismic investigations in the central Upper Rhinegraben

Structure and nature of the Palaeozoic basement based on magnetic, gravimetric and seismic investigations in the central Upper Rhinegraben

The second and most prominent heat contribution is attributed to the composition of the upper crust, in particular to the elevated concentration of heat-producing elements (HPE) in Palaeozoic granitoids (Vilà et al. 2010). Already in the 1970s, the magnetic sur- veys at the ground level of the graben between Strasbourg–Lahr and Wissembourg– Baden-Baden had shown a clear correlation of the magnetic anomalies with temperature anomalies in the Soultz and Eschau ridge areas (Edel et al. 1980). In the northern Vosges, Baden-Baden area, Odenwald and Spessart massifs, the geophysical investigations revealed that these strong magnetizations are related to arc magmatic granites, grano- diorites, diorites and associated volcanites (Edel and Weber 1995) emplaced in the range 340–330  Ma above the southeast dipping subduction of the Rhenohercynian ocean (Krohe 1991; Oncken 1997; Altherr et al. 1999) (Figs. 1b, 4). The 500-km long, 80-km wide magnetic belt consists of a succession of narrower kilometric anomalies. Three of such magnetic belts cross the Palaeozoic northern Vosges and continue towards the NE beneath the sedimentary cover of the Rhinegraben. Baillieux et al. (2013) suggest that

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M5-02 - SITE INVESTIGATION NOTE

M5-02 - SITE INVESTIGATION NOTE

Site Investigation fieldwork is undertaken to gain information on groundwater levels, geological strata, bedrock depth etc. Samples, which are later sent to laboratories for testing, can also be obtained. Investigation of detailed geology and sub-surface soil conditions using surface surveys (land surveys), trial pits, boreholes, soundings (CPT, etc), geophysical methods, etc.

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Connecting hazard analysts and risk managers to sensor information

Connecting hazard analysts and risk managers to sensor information

1. Vecchia, V. A unified approach to probabilistic risk assessments for earthquakes, floods, landslides, and volcanoes. In Proceedings of a multidiscipilinary workshop held in Golden, Colorado November 16–17 1999, Open-File Report 01-324, U.S. Geological Survey; 2001. 2. Douglas, J. Methods and tools for risk evaluation, RISK-NAT. Module 4. Progress report. RP-

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Characterisation of weathered clayey soils responsible for shallow landslides

Characterisation of weathered clayey soils responsible for shallow landslides

Site investigations were made aiming at characterising the soil colluvium and the bedrock within each landform. A de- tailed stratigraphical description was also carried out: weath- ered soil profile description, also in correspondence of land- slide bodies; bedrock characterisation; the presence or ab- sence of ground-water seeps was also recorded. The soil pro- file was established on the basis of a limited number of out- crops and more than 100 trench pits and trench drains with a mean depth of 5–6 m (see Fig. 1 for the location). During the site investigation, samples for laboratory tests were also collected.

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Integrated Hydrogeological and Hydrogeophysical Exploration for Groundwater in parts of Gidan Kwano and Gidan Mangoro, North central Nigeria

Integrated Hydrogeological and Hydrogeophysical Exploration for Groundwater in parts of Gidan Kwano and Gidan Mangoro, North central Nigeria

An integrated geological and geophysical exploration technique is more suited for efficient and successful groundwater potential studies in Basement Complex Terrain such as Gidan-kwano, Gidan-Mangoro, North-central Nigeria than any geophysical method. The hydrogeological and hydrogeophysical investigation of Gidan-Kwano and Gidan-Mangoro was executed in this study. The H-type curve is the dominant curve type in the area. Three lithologic layers were consisting of highly resistive top soil, low resistivity middle layer of weathered/fractures zone and the highly resistive dry fresh basement rock. This signature was consistent in VES curves, geo-electric section and analyzed borehole strata-log. The effectiveness geological and geophysical techniques in delineating subsurface signatures have been demonstrated in this study and it is recommended that this synergy should be sustained.

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Predictive Map of Geoelectric Sections of North and South America

Predictive Map of Geoelectric Sections of North and South America

The electrical characteristics of the study regions were shown to be typical of the continental crust; they show a regular spatial variation and depend on the type of geoelectric structure (depression, massif, fault zone, etc.) and their association with a particular complex of crystalline and sedimentary rocks [11]. Geoelectric mapping also showed that the transition from one geological section to another is accompanied by a change in electrical properties, i.e., geoelectric and geological boundaries usually coincide [11]. In some of the areas mapped, the problem of the boundaries of the inferred regions and the values of ρ j and h j ascribed to

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Geotechnical and Hydrological Characterization of Subsurface for Metallic Minerals Mining Operations in Punjab, Pakistan

Geotechnical and Hydrological Characterization of Subsurface for Metallic Minerals Mining Operations in Punjab, Pakistan

The deformation analysis of the open pit mine slopes is performed using the Rocscience finite element based software Phase 2. The result of the analysis is shown in Figure 10 which shows quite rational patterns of deformation. The maximum deformation is likely to be in order of as high as 700 mm for individ- ual slope riser whereas in the range of 300 to 400 mm for the overall slope. These numbers should become more representative with expanding the geotechnical database for the project and carrying out numerous such analyses with excava- tion stages since the modulus to elasticity in both soils and rocks is not a con- stant rather depend on the changing stress and strain.

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Ownership Not Required: The Expansion of Section 167(h) in CGG Americas, Inc. v. Commissioner

Ownership Not Required: The Expansion of Section 167(h) in CGG Americas, Inc. v. Commissioner

32. See, e.g., Rev. Rul. 83-105, 1983-2 C.B. 51, 51 (“In addition to illustrating, by example, how the various geological and geophysical costs are to be allocated, what constitutes an abandonment as a potential source of mineral production is explained. Rev. Rul. 77­ 188 amplified.”); Rev. Rul. 82-9, 1982-1 C.B. 39, 39 (“The taxpayer previously deducted the costs of obtaining the items as intangible drilling and development costs and has a zero basis in them. Therefore, the taxpayer’s charitable contribution deduction is zero.”); Rev. Rul. 80-342, 1980-2 C.B. 99, 99 (“The drilling expenses are not intangible drilling and development costs subject to the elective provisions of sections 1.263(c)-1 and 1.612­ 4(a) of the regulations; they are capital expenditures allocable to any leases that may be acquired based on information obtained from the well.”); Rev. Rul. 80-153, 1980-1 C.B. 10, 10 (“A ‘bottom hole’ contribution is includible in the recipient’s gross income and must be treated as capital expenditure by the payor.”).

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Evalution Of The Different Foundation Beds At Barwa Area By Using Geophysical And Geotechnical Studies.

Evalution Of The Different Foundation Beds At Barwa Area By Using Geophysical And Geotechnical Studies.

This research involves the geotechnical properties of different foundation beds of Barwa area. The study area is characterized by very gentle topography and lack of sharp relief and is covered by Miocene, Oligocene and Eocene deposits which are mainly composed of sands and gravels intercalated with clay lenses. The investigation results of sands at foundation levels reveal that the average value of effective diameter is 1.59, uniformity coefficient is 25.98, coefficient of curvature is 1.88, friction angle average is 36°.

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Foundation Investigations for the Bhaunrat Dam Project – A Case Study

Foundation Investigations for the Bhaunrat Dam Project – A Case Study

Abstract: The geotechnical investigations play an important role in economic viability and structural stability of a dam project. The geotechnical investigation for dam project involves the borrow area investigations and foundation investigations. The borrow area locations and characteristics decide the economic viability of earthen dam project. Borrow area investigations characterizes the construction material in the vicinity of dam site, depth of construction material, extent of construction material. The foundation investigation is carried out to evaluate the compactness for foundation and abutments for the dam project, treatment to be given to foundation and depth of excavation of foundation. The extent of foundation investigation depends upon the site conditions but it provide the information regarding type of the soil or rock strata in the foundation or abutment at dam site, depth of rock, water table and locations of buried channels, seams, joints and fissures etc. The foundation investigations decide the structural safety of a dam project. The present paper presents the foundation investigations carried out for construction of Bhaunrat Dam Project, Uttar Pradesh.

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ASSESSMENT OF GEOTECHNICAL AND HYDROGEOLOGICAL PROPERTIES OF SELECTED GULLY EROSION SITES IN IKWUANO AREA, SOUTHEASTERN NIGERIA.

ASSESSMENT OF GEOTECHNICAL AND HYDROGEOLOGICAL PROPERTIES OF SELECTED GULLY EROSION SITES IN IKWUANO AREA, SOUTHEASTERN NIGERIA.

ABSTRACT An assessment of the geotechnical and hydrogeological properties as agents in the formation and expansion of gullies in Ikwuano area is presented. Field geological study of the area revealed that it is covered by sedimentary rocks. The soils are lateritic and are the product of intensive weathering that occurs under tropical and subtropical climatic conditions resulting in accumulation of hydrated iron and aluminium oxides. Results of sieves analysis show that the soils at the gully sites have sorting values ranging between 0.42 and 2.3, coefficient of uniformity values ranging between 3.0 and 10, and the coefficient of curvature values ranging between 0.2 and 1.3. These indicate that the soils are fair to well sorted in places. The plasticity indices values ranging between 11.0 and 29 with mean value of about 20 indicate soils of moderate to high plasticity, slight dry strength and easily friable. Value of maximum dry density ranges between 1.83g/cm 3 and 2.12g/cm 3 at optimum moisture contents of between 7.4% and 11.3% reveals that the soils were generally loose. The hydraulic conductivity and transmissivity values as determined from statistical grain size method range between 3.8 ×10 - 4 cm/s to 6.4 × 10 2 cm/s and 3.8 ×10 -2 cm 2 /s to 9.6 ×10 4 cm 2 respectively. These indicate moderate seepage fluxes and adverse pore pressures and are thus easily erodible. From the geotechnical analysis results, recommendations for erosion control such as aforestration, construction of drainages and concrete rip-raps were suggested. KEYWORDS: Hydrogeological, geotechnical, transmissivity, plasticity, Ikwuano area, Nigeria.

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Geological and Geotechnical Assessment of Selected Gully Sites in Sangere Loko Area NE Nigeria

Geological and Geotechnical Assessment of Selected Gully Sites in Sangere Loko Area NE Nigeria

1 ABSTRACT An assessment of geological and geotechnical parameters of selected gully sites in Sangere Loko Area of northeastern Nigeria is presented. Field geological study revealed that the area is underlain by basement rocks consisting of granites and granite gneiss which has been intruded by the Tertiary basaltic rocks. The soils in the area are product of insitu weathering of the underlying basement rocks giving rise to clays, silts, laterites and sand deposites occurring more than 3 meters in depth. Results of sieve analysis indicate that soils at the gully sites have sorting values ranging from 0.204 to 1.434 showing well to poorly sorted soils. Furthermore the mean hydraulic conductivity values of 4.89 x 10 -3 cm/s and mean transmissivity value of 1.24 x 10 -4 cm 2 /s indicate relatively moderately permeability, seepage fluxes and pore pressures which will likely reduce the shear strength of the soils. The plastic limits of the soils vary from 13.15% to 21.90 % whereas the plasticity index varies from 12 % to 21.30 % revealing soils of low to moderate plasticity as well as friable, poorly cohesive soils that are susceptible to gully erosion. The compaction test display maximum dry density values of 1.78 kg/m 3 to 2.21 kg/m 3 with an optimum moisture content values of 6.10 % to 10.20 % revealing generally loose soils that are susceptible to gully erosion. The results of the study were used to infer the surface and subsurface processes that contribute to the formation and expansion of gullies as well as recommendations on how to control the menace of gully erosion in the area were made. Keywords; Geological and geotechnical parameters, basement rocks, insitu weathering, Sangere Loko Area, Northeastern Nigeria

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Prospecting for safe (low fluoride) groundwater in the Eastern African Rift: the Arumeru District (Northern Tanzania)

Prospecting for safe (low fluoride) groundwater in the Eastern African Rift: the Arumeru District (Northern Tanzania)

Abstract. A multidisciplinary research effort, including ge- ological, hydrogeological, hydro-chemical, geophysical and hydrological investigations, was aimed at locating a source of safe groundwater for a district of northern Tanzania, within the western branch of the East Africa Rift Valley, where wa- ter shortage is common and much of the surface water car- ries unacceptable levels of dissolved fluoride. The 440 km 2 study area lies in the northern part of Arumeru district and is dominated by Mt. Meru (4565 m a.s.l.). The local climate is semi-arid, with distinct wet and dry seasons. Four hy- drogeological complexes were identified, occurring within different volcanic formations, either alone or superimposed upon one another. The groundwater flow system was inter- preted from the spatial distribution of the springs, combined with a lithology- and geometry-based reconstruction of the aquifers. The dominant pattern consists of a multi-directional flow from the higher elevations in the south towards the lower areas in the north, but this is complicated by structures such as grabens, faults, lava domes and tholoids. After the identi- fication of the major fluoride source, an interference pattern between groundwater and high fluoride surface water was drawn. Finally, vertical electrical soundings were performed to define the location of aquifers in regions where release of fluoride was prevented. The methodological approach for the prospecting of safe water in a semi-arid, fluoride polluted re- gion was validated by the drilling of a 60 m deep well capable of supplying at least 3.8 l/s of low fluoride, drinkable water.

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Geophysical investigations of Tasmania at multiple scales

Geophysical investigations of Tasmania at multiple scales

CPDs is directly related to geothermal gradient correlating with some factors such as geological history and tectonic evolution, type of the crust (continental or oceanic), and magnetic minerals present within subsurface features. Shallow CPDs are expected in regions linked to geothermal potential, young volcanism and also thinned crust (Abd El Nabi, 2012). Deep CPDs correlate with areas of low heat flow associated with plate cooling (e.g. northwestern Pacific off northeast Japan), while regions characterised by high heat flow coincide with shallow CPDs (e.g. Japan Trenches; Tanaka et al., 1999; Yoshii, 1979). Tanaka et al. (1999) summarised CPD values for different regions correlating with dominating tectonic characters. According to Tanaka et al. (1999), the CPD across geothermal and volcanic areas is ~10 km or less and increases in island arcs and back-arc rift ridges to 15—25 km, it exceeds 20 km depth at continental plateaus and Trenches have the highest CPDs (> 30 km depth). The CPD is generally deeper in continental areas compared to regions of oceanic crust (Tanaka et al., 1999). The CPD in subduction zones correlates with the boundary between the brittle and ductile crustal regime (Doser and Kanamori, 1986). Based on Harrison (1976) and Arkanihamed (1991), the lower crust in the oceanic domain is magnetic as well as the uppermost mantle. There is a correlation between the age of tectonic settings and surface processes reflecting the tectonic stabilisation of the crust: high heat flow rates are observed in younger orogens (e.g. Cermak and Hurtig, 1979) and typically older regions show a lower heat flow (e.g Abd El Nabi, 2012). In addition, Stacey and Banerjee (1974) showed that the Curie temperature estimation depends on the magnetic minerals present within subsurface rocks. Magnetic sources concentrate in one tectonic setting and change the CPD in that area. For example, Jenning (1997) showed that deeper magnetic sources are located under Precambrian lithologies in California.

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Determining of Geotechnical Domain Based on Joint Density and Fault Orientation at Batu Hijau Mine,West Sumbawa-Indonesia (TECHNICAL NOTE)

Determining of Geotechnical Domain Based on Joint Density and Fault Orientation at Batu Hijau Mine,West Sumbawa-Indonesia (TECHNICAL NOTE)

The research area is located at Batu Hijau Mine – PT Amman Mineral Nusa Tenggara, administratively located at the southwestern of Sumbawa, West Nusa Tenggara Province – Indonesia. The research area is controlled by tectonism in accordance to close with the active tectonic plate at southern part of this island. The presence of the active tectonic regime causes of the rich deposit of ore mineralization and intensive of geological structure in this region. The study was focused on how to develop geotechnical domain which is an important aspect for developing of open pit mine design. The data collecting methods are obtaining by the window and scanline geotechnical mapping in line with excavation stage to execute pit slope design. The research result shows that the geological information is very useful to determine the geotechnical domain. It can be used for guidance on developing pit slope design parameter in open pit mining, and other geotechnical purpose such as defining probability of failure, slope movement guidance, and risk assessment.

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