Undrained Shear Strength of Normally Consolidated and Overconsolidated Clays from Pressuremeter Tests: A Case Study

Undrained shear strength (s_u) of foundation soil of Marquette interchange near Milwaukee, Wisconsin was evaluated from the results of a number of pressuremeter tests conducted on normally consolidated (NC) organic silts and overconsolidated (OC) silty clay. The s_u-values were interpreted from traditional closed-form methods. The pressuremeter geometry and test sequence as well as response of the soil profiles were also simulated using axisymmetric finite element (FE) method with Cam-Clay soil model. The Cam-Clay model parameters were estimated from laboratory tests on undisturbed soil samples. Results show that the s_u estimated from the rate of cavity pressure change with volumetric strain (referred to as direct traditional method) is almost twice the s_u estimated from an indirect traditional method that estimates s_u from shear modulus, in situ horizontal stress, and ultimate cavity pressure obtained from the cavity pressure curves. The s_u-values predicted from the FE models are lower than those estimated from the traditional methods and shows that the assumption of infinite pressuremeter length in traditional methods results in overprediction of undrained shear strength by a factor of 1.5 for NC clay and 2.2 for OC clay. The results of finite element analysis considering Cam-Clay soil model and finite length for pressuremeters suggest the undrained shear strength of 63 ± 7 kPa for NC organic silt and 259 ± 68 kPa for OC silty clay.     

First Evidence of Lamprophyric Magmatism from the Konya Region,Turkey: a Genetic Link to High-K Volcanism

In the vicinity of Konya （Turkey）,mafic,micro-porphyritic sub-volcanic rocks intrude into the Mesozoic units,which represents the only example of such a rock type in the region.40Ar/39Ar dating of two whole rock samples from the sub-volcanics gave ages of 13.72±0.13 and 12.40±0.11 Ma,suggesting temporal association to the Late Miocene-Pliocene high-K calc-alkaline volcanism in the region.The mineral chemistry and geochemical data permit us to classify the rocks as ＂minette＂ lamprophyres.They include diopside and phlogopite phenocrysts in a microcrystalline groundmass composed of sanidine,phlogopite,diopside and titano-magnetite.Segregation and ocelli-like globular structures occur commonly in the samples.In terms of major elements,the lamprophyres are calcalkaline,and potassic to ultrapotassic rocks.All the lamprophyres display strong enrichments in LILE （Rb,Ba,K,Sr）,radiogenic elements （Th,U） and LREE （La,Ce） and prominent negative Nb,Ta,and Ti anomalies on primordial mantle-normalized trace element diagrams.Geochemical data suggest that the lamprophyres and high-K calc-alkaline rocks in the region derived from a subduction-modified lithospheric mantle source affected by different metasomatic events.Lamprophyric magmatism sourced phlogopite-bearing veins generated by sediment-related metasomatism via subduction,but high-K calc-alkaline magmas are possibly derived from a mantle source affected by fluid-rich metasomatism.     

A tectonic escape structure: Erciyes pull-apart basin,Kayseri, central Anatolia,Turkey

Abstract

A large sinistral intracontinental transcurrent structure, the Central Anatolian Fault Zone (CAFZ), is located between Erzincan in the northeast and offshore of Anamur county in the southwest of Turkey. Northeastern and southwestern segments of the fault zone are linked to each other by an intervening and approximately N-S-trending transtensional structure, the Erciyes pull-apart hasin (EPB). The Krzihrmak-Erkilet and Dökmeta? segments of the CAFZ bend southwards at about 45°-50° near Kayseri and result in a releasing double bend, which has nucleated both the EPB and its main feature, the Erciyes stratovolcano complex (ESVC) since Middle Pliocene time. The EPB is a ~35-km-wide, 120-km-long, 1.2-km-deep, lazy S-shaped and actively-growing depression with the ESVC forming a high-standing central barrier between the northern and southern parts of the basin. Hence, the EPB appears as two separate basins, namely the ‘Sultansazh?i and Kayseri-Sarimsakli depressions’. However, this is not correct, because development of the EPB and ESVC has been coeval with the volcanic activity producing the ESVC continuing into prehistoric times. Development of the EPB is continuing as indicated by faulted, uplifted and terraced Pleistocene-Early Holocene palaeolake beach deposits, and historical to recent earthquakes. Accumulative throws on the eastern and western margin-bounding faults of the EPB are 1225 m and 720 m respectively and show that basin development has been asymmetrical. © 2001 Éditions scientifiques et médicales Elsevier SAS     

Hydrogeochemistry and arsenic contamination of groundwater in the Rayen area, southeastern Iran

High As contents in groundwater were found in Rayen area and chosen for a detailed hydrogeochemical study. A total of 121 groundwater samples were collected from existing tube wells in the study areas in January 2012 and analyzed. Hydrogeochemical data of samples suggested that the groundwater is mostly Na–Cl type; also nearly 25.62 % of samples have arsenic concentrations above WHO permissible value (10 μg/l) for drinking waters with maximum concentration of aqueous arsenic up to 25,000 μg/l. The reducing conditions prevailing in the area and high arsenic concentration correlated with high bicarbonate and pH. Results show that arsenic is released into groundwater by two major phenomena: (1) through reduction of arsenic-bearing iron oxides/oxyhydroxides and Fe may be precipitated as iron sulfide when anoxic conditions prevail in the aquifer sediments and (2) transferring of As into the water system during water–acidic volcanic rock interactions.     

Comparison of wave equation migration in logpolar and elliptic coordinates

We extend Riemannian wavefield extrapolation to pre- and post-stack migration using 2D logpolar coordinate system in order to enhance imaging of subsurface structures with imaging of dipping reflectors and turning waves. The logpolar coordinate is a coordinate system adequate for propagating both the source and receiver wavefields. The logpolar extrapolation wavenumber introduces an isotropic slowness model stretch to the single square root operator that enables the use of Cartesian finite-difference extrapolators for propagating wavefields in logpolar meshes. Wavefield extrapolation in this coordinate does not require any ray tracing at all and it can be readily extended to high-order finite-difference schemes since it is an analytic extrapolation operator. Two migration examples illustrate the advantages of the logpolar coordinate for imaging complex geological structures. We compared results of post- and pre-stack depth migration in logpolar and elliptic coordinate systems and we found that steeply dipping events can be better imaged in logpolar coordinate than in elliptic coordinate.     

Evaluating the effectiveness of bank infiltration process in new Aswan City, Egypt

Riverbank filtration (RBF) is an efficient and low-cost natural alternative technology for water supply application in which surface water contaminants are removed or degraded as the infiltrating water moves from the river to the pumping wells. In this study, a full-scale RBF site consisting of three vertical wells installed 50 m from Nile bank was investigated. The RBF systems are particularly well suited for providing better water quality than withdrawal directly from the Nile River to produce drinking water for New Aswan city. The study is carried out by taking samples over 1 year from riverbank filtrates wells, Nile River (as induced surface water), and some production wells were collected and analyzed. Physicochemical and microbiological measurements such as turbidity, dissolved oxygen, total suspended solids, total organic carbon, total dissolved solids, electrical conductivity, pH, Fe, Mn, NH₃, NO₂, NO₃, PO₄, Ca, Mg, Na, K, HCO₃, SO₄, Cl, total bacteria, and total coliform were carried out. The results of bank filtrate were compared with those of the natural groundwater and previous reported Nile water. Chemical and bacterial quality parameters of RBF are under the allowable limits for drinking water. Moreover, bank filtration is simultaneously improved the ambient groundwater and cleaned Nile water in the studied area. Result of this full-scale RBF plant showed the effectiveness of riverbank filtration as a proven treatment technique in Nile Valley with a fraction of cost comparing to conventional surface treatment plants.     

Removal of zinc(II) from aqueous solutions using modified agricultural wastes: kinetics and equilibrium studies

In recent years, the need for safe and economical methods to eliminate heavy metals from contaminated waters has necessitated research on the production of low-cost alternatives to commercially available activated carbon. In the present work, in order to enhance the removal of heavy metals from contaminated water, Zizyphus vulgaris wastes were modified chemically to produce an adsorbent rich in carboxylic groups to enhance the removal of heavy metals from contaminated water. Adsorption of Zn(II) ions on the produced adsorbent was then optimized. The optimal ratio for esterification involved the treatment of Z. vulgaris wastes (1 g) with 0.0037 mmol malic acid in the presence of a very small amount of water for 2 h at 140 °C. The maximum values for adsorption capacity, q _max, were 28.7 and 164.6 mg/g on native and modified Z. vulgaris wastes, respectively, at pH 5 and 30 °C with a contact time 2 h and an initial metal ion concentration of 400 mg/L. The equilibrium data were well fitted by the Langmuir and Freundlich adsorption models and demonstrated the significant capacity for Z. vulgaris wastes in the removal of Zn(II) ions from aqueous solutions.     

Bench blasting design based on site-specific attenuation formula in a quarry

This research was performed on the quarry that will be opened to produce aggregates and rock filling material at Catalagzi region at Zonguldak province in Turkey. However, there are some structures which can be adversely affected by blasting at the quarry. These structures are a methane exploration drill hole and a house at the distances of 340 and 390 m, respectively. One of the main goals of this study is to perform a preliminary assessment of possible damage effect of ground vibrations induced by blasting on these structures by risk analysis based on ground vibration measurements. In order to propose a preliminary blast design models separately for aggregate and rock filling material production, six test shots with different maximum charge per delay were planned and fired at the quarry. In these shots, 90 events were recorded. To predict peak particle velocity (PPV), the relationship between the recorded peak particle velocities and scaled distances were investigated. During this investigation, the data pairs were statistically analyzed and a PPV prediction equation specific to this site with 95% prediction line were obtained. And also, this equation was used in the derivation of the practical blasting charts specific to this site as a practical way of predicting the peak particle velocity and maximum charge per delay for future blasting. A risk analysis was performed by using this equation. In the light of this analysis, preliminary blast design models were proposed to be used in this quarry for aggregate and rock filling material production.     

Impacts of human activities and natural inputs on heavy metal contents of many coral reef environments along the Egyptian Red Sea coast

In order to monitor the heavy metals effect coming from both human activities and natural inputs on coral reef environments of the Egyptian Red Sea coast, metal concentrations in thirty- eight coral reef species and nearby sediment samples collected from seven studied sites were analyzed. Four sites represent impacted areas; included from south to north Hamrawein, Safaga and Hurghada Harbours and Ras El-Behar Area. Wadi El-Gemal represents natural input area while Qola'an and Kalawye Reefs are the control areas. Heavy metal contents were measured in both coral skeletons and nearby marine sediments. Both impact areas as well as natural inputs area recorded the highest values of metals compared with the control ones. However, heavy metal contents recorded high values in sediments of Hamrawein Harbour, while coral species recorded high values in Wadi El-Gemal area. Generally, metal variations in coral reef species reflect natural conditions and human activity. On the other hand, there are no clear relationships between concentrations of heavy metals in coral reef species and those in sediments.