A field application for lime stabilization   总被引：2，自引：0，他引：2  

Aydın Kavak  Adnan Akyarlı 《Environmental Geology》2007,51(6):987-997

This study presents the improvements achieved as a result of the lime stabilization application conducted by the joint effort of the Turkish Association of Lime Industrialists and the General Directorate of Rural Services on the 200 m long section of the Ankara Province Yukar? Yurtçu Village road where green and brown clays are dominant. The study also numerically demonstrates the impacts of these improvements on the road section based on the results of various laboratory and field tests. The lime stabilization in field conditions was performed with 5% lime for both clays and was applied as a 30 cm thick single layer. In the soaked California bearing-ratio (CBR) tests conducted in the laboratory, increases that reach up from 16 and 21 times compared to initial soaked CBR values were observed in green and brown clays, respectively, at the end of 28 days. The high increases observed in soaked CBR values would reduce the upper layer thickness of the roads. The similar improvements are also achieved in unconfined compression and plate loading tests. The comparisons performed with the plate loading tests clearly demonstrated the behavior of the surface to lime and its cure impact.  相似文献   

Identification of Microfabric of Kaolinite Clay Mineral Using X-ray Diffraction Technique     

Ajanta Sachan  Dayakar Penumadu 《Geotechnical and Geological Engineering》2007,25(6):603-616

A new method is introduced in this study to identify the microfabric (geometric arrangement of platelets) of cohesive soil using standard X-ray diffractometer. Various sampling techniques are used to prepare the Kaolinite clay samples with different microfabrics to assess the consistency and versatility of the proposed method. This method is based on identifying the presence of basal and prism peaks from the X-ray diffraction pattern and corresponding relative intensity values. The present study also demonstrates the conditions for which Scanning Electron Micrographs (SEM) are not capable of accurately identifying the microfabric of cohesive soils. The method proposed in this study uses relative amplitudes of basal and prism peaks avoiding difficult sample and surface preparation procedures, as used by previous researchers in their microfabric identification methods. The proposed method is found to be a rapid and accurate method for identifying the microfabric of Kaolinite clay and should prove to be valuable for routine implementation for studying structured natural clays.  相似文献   

Evidence for the silicate source of relict soils on the Edwards Plateau, central Texas     

M. Jennifer Cooke  Libby A. Stern  Jay L. Banner 《Quaternary Research》2007,67(2):275-285

Relict soils provide insights into Quaternary soil formation and erosion on the Edwards Plateau of central Texas and into soil-forming processes in karst terranes. Late Quaternary climate-driven soil erosion produced a mosaic of thick and thin soils on the Edwards Plateau landscape. Thick soils on uplands of the Edwards Plateau are interpreted to be relicts of a formerly more extensive soil cover that was eroded during the late Pleistocene to middle Holocene. The relict, thick soils are silicate-rich and most commonly overlie the relatively silicate-poor Cretaceous Edwards Limestone, which supports the idea that the thick soils did not form from weathering of the underlying limestone. Other potential sources of silicates for the relict soils include dust, alluvial sediments, and the Del Rio Clay, a stratigraphically higher but locally eroded clay-rich unit. Here we investigate the geographic distribution, texture, clay-sized mineralogy, rare earth element geochemistry, and neodymium isotope composition of the relict soils. We have found that the relict, thick soils are deeply weathered soils that occur dominantly over the Edwards Limestone and have a high clay content and a neodymium isotope composition that is similar to that of the Del Rio Clay. Thus, we propose that in situ weathering of the Del Rio Clay, along with partial weathering of the upper portion of the underlying Edwards Limestone produced thick chert- and clay-rich soils over resistant limestone. In areas like the Edwards Plateau, where pure limestones are interbedded with clay-rich strata, the overlying clay-rich strata must be considered as a possible silicate source to soils on pure limestone bedrock.  相似文献   

粘土矿物碱耗协同效应研究   总被引：4，自引：0，他引：4  

陈忠  高晓勇 《岩石学报》2000,16(3):459-464

选择蒙脱石,高岭石,伊利石等三种在储层中最党风的储层粘土矿物,两两分别按２Ｌ：０,１：１,０：２质量配比组成复配物系列;在３０℃、５０℃温度下按１：５,１：８,１：１０（ｇ／ｍｌ）固／液比分别与１．６％的Ｎａ２ＣＯ３深液反应８ｈ,３６０ｈ;监测反应前后碱液浓度的变化;计算了各条件下各自的绝对碱耗量。结果表明三种粘土矿物中蒙脱石耗碱最大,高蛉石的耗碱量与伊利石的接近;随着固／液比减小和温度升高,矿物  相似文献   

Geochemical compositional changes at the Pliocene–Pleistocene transition in fluviodeltaic deposits in the Tegelen-Reuver area (southeastern Netherlands)     

D. J. Huisman  G. T. Klaver  A. Veldkamp  B. J. H. van Os 《International Journal of Earth Sciences》2000,89(1):154-169

2 O contents, which can be attributed to the Alpine source supplying fresh, sodic plagioclase-rich material instead of the local, strongly weathered sediments. Increasing K₂O/Al₂O₃ can be attributed to a similar decrease in degree of weathering. However, this trend is disturbed by the loss of K from clay minerals during weathering in organic-rich layers. Local high TiO₂ anomalies, caused by preferential sorting and concentration, are found in most Pliocene sections, but they are absent in the Upper Pliocene and Lower Pleistocene Alpine-derived deposits. This change is probably due to a change in the energy of the fluvial system. Finally, (pyrite-) S contents drop (siderite-) Fe contents rise. Micromorphological observations indicate that the Pliocene pyrite was formed when freshwater deposits were flooded with seawater during short-term events. The decrease in S, and the increase in siderite-Fe, can be attributed to decreasing marine influence, as a result of the marine regression at the Pliocene–Pleistocene transition. Received: 28 August 1999 / Accepted: 2 November 1999  相似文献   

A comparative study of representative 2D microstructures in Shaly and Sandy facies of Opalinus Clay (Mont Terri,Switzerland) inferred form BIB-SEM and MIP methods     

《Marine and Petroleum Geology》2014

A combination of Broad-Ion-Beam (BIB) polishing and Scanning Electron Microscopy (SEM) has been used to study qualitatively and quantitatively the microstructure of Opalinus Clay in 2D. High quality 2D cross-sections (ca. 1 mm²), belonging to the Shaly and Sandy facies of Opalinus Clay, were investigated down to the nanometre scale. In addition Mercury Intrusion Porosimetry (MIP) and X-Ray powder Diffraction experiments have been used to extend characterization of the microstructure to the mm–cm scale on bulk volume sample material. Interestingly, both end-member samples of the Opalinus Clay show qualitatively similar mineralogy and pore characteristics as well as a comparable pore size distribution and pore morphology within the different mineral phases and mineral aggregates. Differences between the facies are mainly due to variations in mineral size and mineral amount present in the alternating layers of the different facies. Six different porous mineral phases have been identified and the pores have been subdivided into ten different pore types. Pores visible in the SEM images are most abundant in the clay matrix and these seem to follow a power law distribution with a power law exponent of ca. 2.25 independent of the sample location. Furthermore, all common mineral grains show characteristic porosity, pore shape and pore size distribution in 2D and are proposed to be considered as elementary building blocks for Opalinus Clay. Combined these homogeneous elementary building blocks make up the heterogeneous fabric of the different facies of Opalinus Clay. Based on extrapolation of the power law size distribution in the clay matrix below SEM resolution results in a porosity of 10–25% for clay rich layers (60–90% of clay matrix), whereas sand and carbonate layers show an extrapolated porosity of 6–14%. These extrapolated porosities are in agreement with water-loss and physical porosity measurements performed on bulk material of comparable samples.  相似文献   

New findings on the tectono-metamorphic history of the western Rhenish Massif (Germany) by K–Ar dating of metasedimentary illite     

Rolf Nierhoff  Norbert Clauer  Gerhard Spaeth 《Journal of Geodynamics》2011

Metapelites, clay-rich sandstones and volcanics from Cambrian, Ordovician and Lower Devonian strata of the western Rhenish Massif underwent a complex regional Variscan tectono-thermal evolution, as shown by mineralogical and K–Ar isotopic analyses of the illite to mica components from three NW-SE transects. The metamorphic degree extended from an anchimetamorphic to an epimetamorphic intensity during two major episodes of illite crystallization at 328 ± 6 and 282 ± 12 Ma. A further late orogenic or post-orogenic extensional activity could also be detected, but not precisely, around 270 Ma, probably recorded by the precipitation of illite in new or reactivated extensional faults with upward moving heat flows.  相似文献   

Prediction of long-term settlement on soft clay using shear wave velocity and damping characteristics     

Mohamad Nor Omar  Colin Peter Abbiss  Mohd. Raihan Taha  Khairul Anuar Mohd. Nayan 《Engineering Geology》2011,(4):259

This paper presents a method of calculating long-term settlement of a loaded pad on soft clay at Klang, Selangor, Malaysia where the soil model is treated as an anelastic material of viscoelastic property. Initially, an elastic shear modulus (G) value from shear wave velocity profiles of the seismic tests from spectral analysis of surface wave (SASW) and continuous surface wave (CSW) tests was obtained. A value of damping (D) at an equivalent elastic strain is then calculated from the hysteresis of the plate load tests corrected to equivalent strain using the Damping–Strain formula. The calculated elastic settlement and its equivalent damping are then used to calculate the long-term settlement by applying the generalised viscoelastic formula. Comparisons to traditional methods of settlement predictions were made and the viscoelastic formula has shown better agreement to the observed settlement. Further modification of the settlement formula is introduced to improve the settlement accuracy to 10%.  相似文献   

Sensitive grain-size records of Holocene East Asian summer monsoon in sediments of northern South China Sea slope   总被引：3，自引：0，他引：3  

Jie Huang  Anchun Li  Shiming Wan 《Quaternary Research》2011,75(3):734-744

Changes in paleoenvironments over the last 17,500 yr have been documented by a high-resolution clay mineralogy and grain–size records of Core KNG5 from the northern slope of the South China Sea. Our results indicate that clay minerals are mainly from the Pearl River from 17,500 to12,500 cal yr BP, and the South China Sea modern current system began to form since 12,500 cal yr BP, as a result, Taiwan turns to be the major contributor of clay minerals after 12,500 cal yr BP. Two grain-size populations with high variability through time were identified in the 13–28 μm and 1–2.2 μm grain-size intervals. The 1–2.2 μm grain-size population are mainly controlled by provenance supply and current transport. The 13–28 μm grain-size fraction could be controlled mainly by the sea-level change. The 1–2.2 μm grain-size population record demonstrates that East Asian Summer Monsoon intensity generally follows changes in insolation and that the response is similar for a large area of China and other northern low-latitude records, implying the globality of the monsoon evolution since Holocene. The anomalous environmental conditions in the northern South China Sea may imply intensified ENSO activity during the late Holocene.  相似文献   

Numerical analysis of an embankment built on soft soil reinforced with deep mixing columns: Parametric study     

Paulo J. Venda Oliveira  João L.P. Pinheiro  António A.S. Correia 《Computers and Geotechnics》2011

The behaviour of an embankment built on normally consolidated soft soil reinforced with deep mixing columns is studied using a coupled soil–water formulation. The numerical predictions are analysed in terms of settlements, increments in vertical effective stresses and excess pore pressures. Firstly, the effectiveness of the use of deep mixing columns is studied. Afterwards, a parametric analysis is performed to study the influence on the soil-columns system of the replacement ratio (columns’ spacing), the deformability of the embankment and columns, and the coefficient of vertical permeability of the columns.  相似文献