scholarly journals Peat stratigraphy mapping using ground penetration radar and geotechnical engineering implications

2017 ◽  
Vol 5 (2) ◽  
pp. 46
Author(s):  
Godfrey Akpabio ◽  
Ubong Johnson ◽  
Calrlos Vargas Cana ◽  
Okechukwu Agbasi
Keyword(s):  
Geotechnical Engineering ◽  
Young Modulus ◽  
Silty Sand ◽  
Silty Clay ◽  
Fibrous Peat ◽  
Field Samples ◽  
Dahomey Basin ◽  
Sampling Window ◽  
Survey System ◽  
Peat Stratigraphy

A Combined Land and Marine Ground Penetrating Radar (GPR) surveys was carried out in Southwestern part of Lagos, Badia, Nigeria with a view of delineating the subsurface peat stratigraphy that would aid geotechnical engineering design of the appropriate soil stability processes. The GPR study was conducted along eight parallel traverses trending East-West, using the Geophysical survey system incorporated (GSSI) SIR-3000 200MHZ Monostatic shielded antenna. Geographically, the study area is approximately between latitude 715000N and 716000N and longitude 538600E and 540300E of the universal traverse Mercator. The antenna was present with three gain points in order to improve the scans during data acquisition while 33 scans per meter were taken (representing 3cm station spacing) with a sampling window of 400ns with offset of +25ns.The topography is generally flat with localized undulations due to sand heaps from canals dredging and sand filling activities in the area. The peat depth was found to vary from 1.5m to 6m and the thicknesses from traverse one (1) to eight (8) on chainage 625m to 1100m. The area belongs to Dahomey Basin which is also known as Dahomey Embayment or Benin Benin or as West Nigeria Basin. The mineralogy, micro-fabrics and Morphology of the delineated stratigraphy was determined using the Scanning Electron Microscope (SEM) and X-Ray diffraction (XRD) methods. The results obtained revealed the presence of five subsurface (Topsoil/ sand filled Layer, Silty Clay, Peat, sandy Clay and Silty Sand) geological Layers, distinct geomorphological features, and high, moderate and low amplitudes, to continuous and discontinuous planer relax Facies structures. SEM and XRD analyses of the field samples obtained showed the dominance of Kaolinite, illite and quarts minerals in the clay/peat mapped. The derived engineering parameters suggest that the peat found in the study area are “fibrous peat” with low strength and medium to low bedding stress. It is observed that the peat generally depict high compressibility value, low internal frictional angle, they exhibit low elastic properties such as low shear modulus, low bulk modulus and young modulus values. The findings confirm the efficacy and relevance of GPR technique for pre-construction engineering investigation.

A Destructive Field Study on the Behavior of Pile under Ten

2010 ◽  
Vol 163-167 ◽  
pp. 4524-4528
Author(s):  
Shi Min Zhang ◽  
Gang Wei
Keyword(s):  
Skin Friction ◽  
Load Test ◽  
Silty Sand ◽  
Silty Clay ◽  
Test Results ◽  
Bored Pile ◽  
Tip Resistance ◽  
Stress States ◽  
Sand And Gravel ◽  
Different Soils

This paper involves a destructive full-scale load test on long bored pile instrumented with strain gauges along the shaft. The load-displacement response, the distribution of axial force, and the thresholds of displacement for fully mobilizing the skin resistances in different soils in tension case were discussed in this paper. The field test results show that the measured tip resistance in the pile under tension is near zero during the whole loading, and the softening is accompanied with a reduction in skin friction when the skin friction is fully developed. It also can be investigated that the threshold of displacement for fully mobilizing skin friction is different even if in the same soil type due to different soil stress states. Generally speaking, the thresholds of relative pile-soil displacement for fully mobilizing skin frictions in the sandy silt, silty sand mixed silt, silty clay, silty clay mixed sand and gravel are about 4 mm, 11 mm, 7 mm, 6 mm, and 5.5 mm, respectively.

REFLECTION COEFFICIENTS AND BOTTOM LOSSES AT NORMAL INCIDENCE COMPUTED FROM PACIFIC SEDIMENT PROPERTIES

Geophysics ◽  
1970 ◽  
Vol 35 (6) ◽  
pp. 995-1004 ◽  
Author(s):  
Edwin L. Hamilton
Keyword(s):  
Normal Incidence ◽  
Silty Sand ◽  
Reflection Coefficients ◽  
Silty Clay ◽  
Sediment Properties ◽  
Compressional Waves ◽  
Sea Floor ◽  
Sediment Types ◽  
The Pacific ◽  
Clayey Silt

Rayleigh reflection coefficients and bottom losses of compressional waves at normal incidence on the water‐sediment interface are computed with values of density and velocity measured in sea‐floor sediment samples; main sediment types in three major environments of the Pacific and adjacent areas are included. Some typical average computed values of acoustic bottom loss at normal incidence in db are (1) continental shelf: sands, 8; silty sand, 10; sandy silt, 14; silty clay, 16; (2) abyssal plain: clayey silt, 17; silty clay and clay, 21; and (3) abyssal hill: silty clay and clay, 17. Comparisons with actual measurements at sea by several investigators demonstrate the validity of the approach.

Evolution of Tidal Flats in the Northern Part of the Po Delta (Italy):  A Strategy for Future Buiding-with-Nature Management

2021 ◽  
Author(s):  
Riccardo Brunetta ◽  
Paolo Ciavola
Keyword(s):  
Tidal Flat ◽  
Central Area ◽  
Tidal Flats ◽  
Silty Sand ◽  
Nature Management ◽  
Silty Clay ◽  
Po River ◽  
Sediment Distribution ◽  
Clayey Silt ◽  
River Floods

<p>In the period 1950s-60s, the Po river Delta (Northern Italy) was hit by several floods. Agricultural fields were covered by water and many of them remained submerged since. As a consequence of the massive sediment injection into the system, this lead to the birth of new tidal flats around the tip of the Delta. The evolution of these environments over 50 years was studied, as they may be taken as an example for future reconstruction of intertidal areas. The sediment distribution and the morphological evolution of a young tidal flat of about 10 ha located in the Northern part of the Po della Pila branch were studied by undertaking fieldwork since October 2018, including detailed topographic surveys using a UAV, sedimentological analyses, and a study of sediment deposition rates. An extended crevasse splay covers the central part of the flat. The granulometry is predominately fine (Silty clay and Clayey silt), except for the central area, where the sand percentage increases (Loam and Silty sand). This surface distribution is uniform down to ~10 cm; the sand percentage increases instead within the sediment column from ~10 to 25 cm next to the mouths of the channels. The tidal flat experienced a positive sediment budget and it was characterized by higher rates of accretion after the Po river floods. These observations suggest that the tidal channels are fed by sediment from the Po River branch. Orthophotos from the 1950s show that the tidal flat is about 17 - 20 years old and its formation was influenced by human intervention and river floods. The work aims at finally comparing this case study with other tidal flats and salt marshes worldwide characterized by similar and different tidal regimes, to identify the optimal elevation for vegetation to establish and flourish, to support the future restoration of these environments.</p>

Numerical Analysis of Slot Stability during the Supper-Deep Diaphragm Wall Construction

2013 ◽  
Vol 438-439 ◽  
pp. 1043-1047
Author(s):  
Bao Zhu Yang ◽  
Shu Chao Zhang ◽  
Kai Yun Luan
Keyword(s):  
Specific Gravity ◽  
Numerical Models ◽  
Silty Sand ◽  
Diaphragm Wall ◽  
Silty Clay ◽  
Soil Cement ◽  
Guide Wall ◽  
Wall Construction ◽  
Subway Stations ◽  
The Stability

Two subway stations of line Z1 were built in Tianjin cultural center and Tianjin Yujiapu traffic hub. The diaphragm wall depth of the two stations was more than 60 m. The geological and hydraulic conditions were different in the two site. Keeping stability of slot wall was the key of supper-deep diaphragm wall construction to the both stations. Two 3D numerical models were built by ABQUS software to simulate the grooving process. The conditions of different slurry specific gravity and grooving depth were calculated. The deformation laws of the slot wall and ground settlement around the slot wall were studied. The results showed the upper soft silty clay and deeper silty sand layers were easy collapse. Finally, some technologies such as "] [" type guide wall, properly improving slurry specific gravity, soil cement mixing reinforcement were suggested to improve the stability during the diaphragm wall construction of the two stations.

scholarly journals Peat stratigraphy mapping using ground penetrating radar and geotechnical engineering implications

2014 ◽  
Vol 2 (2) ◽  
Author(s):  
Adekunle Adepelumi ◽  
John Akindulureni ◽  
Christian Agih ◽  
Babakayode Olubodun ◽  
Isaac Evinemi
Keyword(s):  
Ground Penetrating Radar ◽  
Geotechnical Engineering ◽  
Ground Penetrating ◽  
Peat Stratigraphy

scholarly journals Distribution and diversity of cumacean assemblages in Admiralty Bay, King George Island

2011 ◽  
Vol 32 (4) ◽  
pp. 341-354 ◽  
Author(s):  
Krzysztof Pabis ◽  
Magdalena Błażewicz-paszkowycz
Keyword(s):  
Abundant Species ◽  
Silty Sand ◽  
Silty Clay ◽  
Central Basin ◽  
Depth Range ◽  
King George Island ◽  
Admiralty Bay ◽  
Core Species ◽  
Sandy Clay ◽  
Key Species

Distribution and diversity of cumacean assemblages in Admiralty Bay, King George IslandEleven species of cumaceans were found in 105 samples collected in Admiralty Bay (King George Island) in the summers of 1984/85 and 1985/86, from 20 to 500 m depth range. Four cumacean assemblages were distinguished using the multivariate analysis. They were characterized by the dominance of one or two species often with low density values. Two assemblages were found in open waters of Admiralty Bay. The first inhabited on sandy-clay-silt and silty-clay-sand bottom deposits in the depth range from 140 to 330 m, withCampylaspis maculata(1.6 ± 2.1 ind./0.1m2; F = 72.4%) andLeuconsp. (1.4 ± 1.6 ind./0.1m2; F = 68.9%) as key species. The second assemblage was found in the depth range from 50 to 120 m with silty-sand sediments, and it was characterized by the presence of Vauthompsonia inermis (6.5 ± 6.6 ind./0.1m2; F = 92.0%). A third assemblage was found in shallow waters influenced by glaciers in the bottom area of Ezcurra Inlet. It was characterized by sandy-clay-silt sediments and the presence ofEudorella splendida(14.6 ± 9.4 ind./0.1m2; F = 100.0%) as a core species. The last assemblage was found in the shallow sublittoral (50-100 m) of Ezcurra Inlet and the central basin, withDiastylis anderssoni armata(1.5 ± 1.1 ind./0.1m2; F = 85.7%) andDiastylopsis goekei(1.1 ± 1.0 ind./0.1m2; F = 71.4%) as the most frequent and abundant species.V. inermisis considered a eurytopic species with high frequency in the whole material, and was present in all four distinguished assemblages.E. splendidaandD. goekeiwere also recorded in each of the assemblages, but their total frequency was lower.

scholarly journals The use of Geoeletric Methods for Post-foundation Assessments of Distressed Buildings in Ebute-meta, Mainland Local Government Area of Lagos State

2021 ◽  
pp. 104-119
Author(s):  
O. J. Airen
Keyword(s):  
Soft Clay ◽  
Maximum Depth ◽  
Silty Sand ◽  
Silty Clay ◽  
Clayey Sand ◽  
Near Surface ◽  
Cone Resistance ◽  
Sandy Clay ◽  
Geotechnical Investigations ◽  
Support Engineering

Geophysical and geotechnical investigations were combined to investigate the immediate causes of the distresses and foundation failures of buildings in Ebute-Meta area of Lagos, south-west Nigeria. Six (6) traverses were mapped in the study area across which six (6) 2D Wenner ERI, and fourteen (14) VES geophysical data were acquired. One (1) boring and five (5) CPT geotechnical data were also acquired. 2D ERI results reveal that resistivity values vary from 4.62 – 293 Ωm across the study area. Three resistivity structures were identified which denoted peat/clay, sandy clay, clayey sand and sand. The resistivity of the peat/clay varies from 4.62 – 27.9 Ωm with thickness varying from 12 - 25 m. The sandy clay varies in resistivity and thickness values from 26 – 86 Ωm and 8 – 29 m respectively. The clayey sand from 84.4 – 182 Ωm and 10 -15 m, and sand, having resistivity and thickness values of 293 Ωm and 3 – 5 m. The VES reveals similar results to the 2D ERI, delineating six geoelectric layers which are the topsoil, peat, clay, sandy clay, clayey sand and sand at maximum depth of 35.8 m. The borehole (BH) reveals a maximum boring depth of 45 m with eight zones comprising dark grey sandy clay, firm to stiff silty clay, soft, dark organic silty peaty clay, grey silty sand, dark grey silty sandy clay, dark grey organic peaty clay, grey silty sandy clay and medium dense to dense grey sand with occasional gravels. The CPT, which penetrated a maximum depth 15.8 m reveal that the cone resistance values vary progressively from 0 – 162 kg/cm2indicating very soft clay to soft clay near-surface and medium dense to dense geologic material at deeper depth. The peat/clay delineated by the 2D ERI and VES at 5 – 25 m depth with resistivity value varying from 4.62 -17 Ωm in the study area, and also revealed in the BH at 5.75 – 27.75 m depth as soft, dark organic silty peaty clay, having cone resistance values varying from 0 – 20 kg/cm2 is laterally extensive and incompetent to support engineering foundation.

scholarly journals Prediction of Compaction Parameters of Khon Kaen Loess Soil

2020 ◽  
Vol 17 (12) ◽  
pp. 1367-1378
Author(s):  
Prinya CHINDAPRASIRT ◽  
Apichit KAMPALA ◽  
Anukun ARNGBUNTA ◽  
Suksun HORPIBULSUK
Keyword(s):  
Loess Soil ◽  
Silty Sand ◽  
Unit Weight ◽  
Soil Parameters ◽  
Silty Clay ◽  
Fine Grained ◽  
Dry Unit Weight ◽  
Khon Kaen ◽  
Fine Grained Soil ◽  
Compaction Energy

Soil stratum in Khon Kaen province, located in Northeast of Thailand, is well-known as a wind-deposited fine-grained soil (i.e. silty sand and silty clay). It is normally called “Loess or Khon Kaen Loess”.  This soil in disturbed stage is usually extracted from the borrow pit and subsequently compacted for infrastructure applications. The compaction resulted in silty sand or silty clay aggregation with unpredictable properties. Although required for infrastructure design, studies on Khon Kaen Loess are limited. Thus, this research examines the compaction behavior and predicts soil parameters at various clay contents under a series of compaction energy on Khon Kaen Loess. The results showed that the maximum dry unit weights of samples could be related to the dry unit weight at plastic limit (PL), while the optimum water content (OWC) was correlated linearly with the PL. The samples with higher PL presented the higher OWC. In addition, the maximum dry unit weight and OWC of samples could be estimated using the developed equations validated with the other research results.

scholarly journals Analisis Potensi Likuefaksi dan Perbaikan Tanah dengan Stone Column: Studi Kasus pada Coal Shelter PLTU Lontar, Banten

2021 ◽  
Vol 17 (1) ◽  
pp. 27-35
Author(s):  
Yuli Fajarwati ◽  
Rama Indera Kusuma
Keyword(s):  
Safety Factor ◽  
Soil Improvement ◽  
Silty Sand ◽  
Stone Columns ◽  
Stone Column ◽  
Silty Clay ◽  
High Demand ◽  
Research Site ◽  
New Generation ◽  
Liquefaction Analysis

ABSTRACT The high demand for electricity needs requires the availability of new generation sites. The new plant developed is a PLTU in Lontar. The condition of coal shelter as a research site dominated by silty clay and silty sand and located in the earthquake zoning is high that the planning of the coal shelter area must accordance with the feasibility of building establishment, it is necessary to analyze the potential liquefaction and improvement methods. Soil improvement efforts to reduce the potential for liquefaction include soil improvement with stone columns. The method of liquefaction analysis in this study uses the method developed by Idriss and Boulanger. The results of the analysis of the potential for liquefaction at BH-1 occurred at a depth of 3-16 m and at BH-3 the potential for liquefaction occurred at a depth of 4-24 m. Potential of the thickest layer for liquefaction is at BH-3 with a depth of 24 m. Improvement with a stone column can reduce the potential for liquefaction and can increase the value of the safety factor against the potential for liquefaction at the coal shelter location. Improvement analysis with a stone column using Plaxis software, the value of the safe factor after installing the stone column at BH-1 FS 2.89, at BH-3 FS became 2.65. ABSTRAKBanyaknya permintaan kebutuhan listrik yang tinggi diperlukan ketersediaan lokasi pembangkit baru. Pembangkit baru yang dikembangkan yaitu PLTU Batubara di Lontar. Kondisi coal shelter sebagai lokasi penelitian yang didominasi oleh lapisan tanah lempung kelanauan dan pasir kelanauan serta berada pada zonasi gempa cukup tinggi sehingga perencanaan area coal shelter harus memenuhi syarat kelayakan pendirian bangunan, maka perlu dilakukan analisis potensi likuefaksi serta metode perbaikannya. Upaya perbaikan tanah untuk mengurangi potensi likuefaksi yaitu perbaikan tanah dengan stone column (kolom batu). Metode analisis likuefaksi pada penelitian ini menggunakan metode yang dikembangkan oleh Idriss dan Boulanger. Hasil analisis potensi likuefaksi pada titik BH-1 terjadi di kedalaman 3-16 m dan pada titik BH-3 potensi likuefaksi terjadi pada kedalaman 4-24 m. Lapisan yang paling tebal mengalami potensi likuefaksi ada pada titik BH-3 dengan kedalaman 24 m. Perbaikan dengan stone column dapat mengurangi potensi likuefaksi dan mampu meningkatkan nilai faktor keamanan terhadap potensi likuefaksi di lokasi coal shelter. Analisis perbaikian dengan stone column menggunakan software Plaxis, nilai faktor aman setelah dipasang stone column pada titik BH-1 FS 2,89, pada titik BH-3 FS menjadi 2,65.

Using Paper as Reinforcement in Silty Sand

2012 ◽  
Vol 535-537 ◽  
pp. 1397-1401
Author(s):  
Amin Chegenizadeh ◽  
Hamid Nikraz
Keyword(s):  
Aspect Ratio ◽  
Modulus Of Elasticity ◽  
Civil Engineering ◽  
Geotechnical Engineering ◽  
Reinforced Soil ◽  
Silty Sand ◽  
Compression Tests ◽  
Unconfined Compression ◽  
Pavement Engineering ◽  
Grade Material

Reinforced soil has been among the most effective soil modification materials. Its use has been expanded rapidly into civil engineering, geotechnical engineering and pavement engineering. Reinforcing subgarde in pavement systems has always been an issue. This study focuses on effect of paper inclusion on the modulus of elasticity of subgrade material. Paper was used for this investigation. Paper contents and aspect ratio have been changed during these tests. The paper percentage varied from 0 % (for unreinforced samples) to 20%. Silty sand was used as sub grade material. Unconfined compression tests were carried out to investigate behaviour of the composite under different condition. The paper reinforcment length and paper reinforcment content found to play important rule on the modulus of elasticity of paper reinforced samples. Furthermore it was observed that ductility of sample increased by paper inclusion.

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