Hard Clay Research Articles

The palynology of the First Hard Clay Layer (late Pleistocene) from the Yangtze delta, China

This paper reports on palynomorphs of environmentally diagnostic significance that were recovered from the First Hard Clay Layer, a widely distributed stratigraphic unit of late Pleistocene age in the Yangtze delta and adjacent areas in China. The palynomorphs represent the Last Glacial Maximum (LGM) and provide the first palynological evidence for reconstructing the sedimentary environment. The high abundance of the algal palynomorph Concentricystes indicates that the Hard Clay Layer is a freshwater deposit. Dinoflagellate cysts occur in low abundance suggesting that the area had minor marine influence. Spore and pollen assemblages show that the regional upland vegetation of the Yangtze delta and adjacent areas was a broadleaved and coniferous mixed forest with meadows present in the riverine wetlands and on the floodplains. The forest taxa are indicative of a temperate climate and show that the LGM was not a continuously cold and dry period, but was punctuated by relatively warm and relatively wet periods. The palynomorph assemblages indicate that the First Hard Clay Layer in the Yangtze delta and adjacent areas is of lacustrine-fluvial origin, rather than aeolian origin as some researchers have suggested.

Characteristics of aquifer system deformation in the Southern Yangtse Delta, China

Excessive groundwater pumpage has caused regional cones of depression and severe land subsidence in the Southern Yangtse Delta, China. The characteristics of aquifer system compaction are complex because of the difference in the types, compositions and structures of the soils that the hydrostratigraphic units are composed of, and in the histories of groundwater level change the hydrostratigraphic units have experienced. Based on the data measured from extensometer groups and observation wells, the characteristics of deformation for individual hydrostratigraphic units are analyzed. The results show that different hydrostratigraphic units have different kinds of deformation and that an identical unit may also present different deformation characteristics, such as elasticity, elasto-plasticity, and visco-elasto-plasticity, at different sites of the cone of depression or in different periods. If the groundwater level rises continuously and remains constant later, the aquifers and the aquitard units that consist of hard clay primarily exhibit elastic behaviour, but the aquitard units that consist of soft clay deform plastically and by creep and exhibit visco-elasto-plastic behaviour. If the groundwater level falls but is much higher than the previous lowest value, aquifers and aquitards consisting of hard clay exhibit elasto-plastic behaviour. If the groundwater level falls below the previous lowest value, aquifers and aquitards consisting of hard clay deform plastically and by creep and exhibit visco-elasto-plastic behaviour.

Rheological characterization of a sedimentary formation from a stress profile inversion

SUMMARY Detailed stress measurements have been carried out within a sedimentary sequence composed of a hard-clay formation laying horizontally between two limestone units, in the eastern Paris basin (France). Orientations of the minor and major horizontal principal stresses are found to be in good agreement with the direction of major shortening that prevailed during the last tectonic stage. However, their magnitudes exhibit an intriguing evolution with depth. While the magnitude of the maximum horizontal stress slowly but regularly increases with depth, the magnitude of the minimum horizontal one is larger in the hard-clay formation than in the surrounding limestone units, contrary to expectation from simple elastic considerations. An analytical calculation demonstrates that the genesis of the current stress state may be reproduced by taking into account horizontal strains in two different directions and simulating erosion of part of the overburden with a viscoelastic model for the hard clay and an elastic behaviour for the limestone. However, the elastic constants that are derived for the limestone in order to fit the measured stress field correspond to a material that is more deformable and has a lower Poisson's ratio than predicted by laboratory tests. This discrepancy may be explained by a slow, long-term, deformation process in the limestone, possibly associated with pressure solution.

Evaluation of ground information with respect to EPB tunnelling for the Thessaloniki metro, Greece

The Thessaloniki Metropolitan Railway comprises two separate ~6 m diameter parallel tunnels with an ~8 km stretch each and 13 stations. The geology of the urban area of Thessaloniki is characterised by the presence of Neogene and Quaternary deposits. The base formation for the project area is a very stiff to hard red clay, dating to Upper Miocene-Pliocene. Upon this formation, Quaternary sediments have been deposited, most of which comprise sand and/or gravel in a clay-silt dominated matrix, covered in places by anthropogenic fill. Ground investigation campaigns incorporated a significant number of sampling boreholes and in situ and laboratory testing. This information was elaborated in order to obtain a better geological understanding and a geotechnical zonation of the ground with respect to mechanized tunnelling. EPB M appears to be the reasonable choice for the project in all aspects of tunnel safety and tunnelling performance. The characteristics and parameters of the soils and the hydrogeological regime directed towards this selection and it is expected that all the objectives, such as settlement and ground movements control, water table level maintenance and adequate performance, will be met by an EPBM provided it is properly operated

Quasi-Solid Dye-Sensitized Solar Cells Containing Nanoparticles Modified with Ionic Liquid-Type Molecules

Gel electrolytes for quasi-solid dye-sensitized solar cells (QDSC) are reported. The gel electrolyte consists of ionic liquids and nanoparticles modified with imidazolium cations. Ionic liquid-type gel electrolytes containing nanoparticles are well-known. The difference between previous reports and this report is that imidazolium cations are bonded to nanoparticles through Ti–O–CO–bonds and long alkyl chains. The role of the long alkyl chains turns out to be critical for high performances. When unmodified nanoparticles are added into ionic liquids until the gel becomes of clay-like hardness, the photovoltaic performances decrease with an increase in the bare nanoparticle content. However, the decreases in photovoltaic performances are retarded when surface-modified nanoparticles are added. Photovoltaic performances increase with an increase in the chain lengths connecting nanoparticles and imidazolium cations. When the chain length becomes 12 and counter anion is , solidification occurs without losing the performance of DSCs having the parent liquid electrolytes. The photocurrents of QDSCs do not decrease even when the ratio (nanoparticles/ionic liquids) increases to 0.9 and the feature looks like hard clay. Ionic paths between nanoparticles are discussed.

Dye Sensitized Solar Cells Consisting of Ionic Liquid and Solidification

Two crucial research items on dye sensitized solar cells (DSC), increasing photovoltaic performances and solidification of liquid electrolytes, are reported. A direction to increasing photo-voltaic performances of DSCs is proposed. An interface between TiO2/dye and an electrolyte layer is focused on. It is proved that better coverage of TiO2 layers with dye molecules increases photovoltaic performances. The results are discussed by using electron diffusion coefficient and electron life time in TiO2 layers. Another crucial research item is solidification. Liquid electrolytes are quasi-solidified without decreasing the parent liquid type DSCs, where Grotthuss type mechanism are introduced to the solidified electrolytes. Because of this, charge carrier can move swiftly even in the hard clay like electrolytes.

Effect of mechanical site preparation and fertilisation on early growth and survival of a black pine plantation in northern Greece

Pine plantations on selected sites in the extensive zone of degraded oak coppice of northern Greece are deemed necessary for increasing wood production in the area and suitable site preparation may accelerate early tree growth. Seven site preparation treatments including raking (R), with sub-soiling (RS), disc harrowing (RD), tine ploughing (RT) and their combinations (RSD), (RDT) and (RSDT) were compared for the establishment of black pine (Pinus nigra Arn) in an oak coppice site, of conglomerate parent material at Anthrakia, northern Greece. The randomised blocks trial of three replications and 110 trees per treatment, half of which were fertilised with 150 g NPK per plant, was assessed at the age of 15 years for diameter, dominant tree height and survival. There was no significant difference between the treatments in any of the traits examined, nor did the fertilisation had any effect. Only the fertiliser × treatment interaction was found significant at p<0.001 for dominant height, accounting for 37% of the observed variation in this trait. The lack of response to site preparation treatments may be attributed to the hard Bt3 clay horizon, extending beyond cultivation depth (50 cm), that prevents the roots penetration into deeper moist soil layers. The F × T interaction, where the combination of (RSDT) treatment and fertiliser was found to accelerate tree height growth in relation to the same treatment without fertiliser, indicates that thorough soil cultivation is needed for fertilisation to be effective in such sites.

Procedure for Determination of the Long-Term Creep Rate and Creep Deformation of Semi-Hard and Hard Clayey Soils

A procedure is proposed for determination of the creep rate and creep deformation at any time from results of short-term tests of the single-plane shear or uniaxial crushing of semi-hard and hard clays. Calculations performed from proposed formulas indicated completely satisfactory convergence of creep parameters with parameters observed in long-term tests. This enables us to recommend these calculations for the design and construction of appropriate structures.

Middelalderlige kirkelader i Danmark

Middelalderlige kirkelader i Danmark

Engineering geological properties of Miocene hard clays along the middle line of the North?South Diversion Water Project in China

Miocene hard clays are widely distributed in eastern China and are associated with extensive damage to engineering structures. This paper presents the engineering geological properties of Miocene hard clays along the middle line of the North–South Diversion Water Project (NSDWP), including areas of the Nanyang Basin as well as the Fangcheng-Baofeng and Handan-Yongnian regions. Results of laboratory testing show that beneath the weathering zone the Miocene hard clays have similar engineering geological properties, including a high clay fraction with significant montmorillonite, high physico-chemical activity, high water content and high to very high shrink/swell. The effects of wetting and drying cycles on the swelling potential of the hard clays are summarized and attention drawn to the importance of these when considering excavation and construction.

Geotechnical classification and distribution of the quaternary deposites in basrah city south of iraq

as due to the strategic importance of basrah city, south of iraq, the architectural development of the city requires a great deal of studies of the geo technical properties .engineering behaviors and classification of the soil bearing strata represented by the quaternary deposites for such purposes a number of (121) sites distibuted randomly all around the city through (491) boreholes of depths (10-48) M below mean sea level are studied. the data are obtained from the test results of (SPT), grain size distribution and the atterberg's limits the quaternary deposites are classified into two main groups : firstly is the cohesive deposites represented by the recent clay and silty clay as well as alhammar formation deposits. secondly is the cohesionless deposits represented by sands of dibdiba formation according to the consistency of cohensive deposits and the compactness of the cohesionless deposits, ten strata can be identified starting from the ground surface , as follows. hard brown silty clay, very stiff brownish-grey silty clay or clayey slit, stiff grey clayey slit, medium stiff grey clayey slit laminated with slit, soft grey clayey slit laminated with slit, medium stiff grey clayey slit, stiff grey clayey slit, very stiff grey clayey slit & sandy clayey slit, hard brown clayey slit and very dense grey sand with slity sand

模型実験に基づく,中間土中のNon-displacement pileの先端支持力

Model tests of Non-displacement piles in hard cohesive soil and sand were performed in which void ratio and drained shear strength were adopted as factors. The results of these model tests and the model tests in hard clay which were published in 1998(cf.Ref. 1) led to the following conclusions,: (1) The void ratio which changes greatly the relationship between the point bearing capacity and settlement of the pile exists between 0.7 and 1,0. It is very important to the behavior of the pile tip (2)The proposed approach for estimating settlement less than about 20% of pile diameter is generally consistent with model test results.

Life in Minor League Baseball As a Chicago Cub Recruit--Half a Century Ago

My entry into Minor League Baseball came during the Second World War, just before D-Day 1944. There were only eleven Minor Leagues in operation at that time, including the independent Mexican League. By 1948, the year I left the Cubs organization, the minors had fifty-two leagues in operation, from Class-D ball all the way to triple-A. There were 5,000 Minor League players assigned to the teams in these leagues. Shortly after graduation from DePaul University, I signed a contract with the Chicago Cubs on the recommendation of an old Cubs fan, William K. Fred, who had seen me play sixteen-inch softball in Chicago's Windy City League. He told Jack Sheehan, the director of the Chicago Cubs Minor League operations, that he thought I would be a good prospect for the Cub organization. Sheehan agreed to give me a tryout. He called and asked me to come down to Wrigley Field early one afternoon when the Cubs were in town. I reported, and he showed me to the Cubs locker room and had the club houseboy provide me with a uniform. The Cubs were finished with their batting practice and were taking infield. The outfielders were catching fly balls and throwing to different bases. I was told to go out there and throw in with Andy Pafko, the great Cubs center fielder. I caught some fly balls and threw to third and home, did some wind sprints, and it was time for the game to start. I came in, took my shower, and reported to the Cubs office. After I talked to Jack for a bit, he proceeded to tell me that he thought I might have some possibilities and, if I agreed, he would sign me to a Cubs contract and have me report to their Class-D Minor League affiliate in Tennessee at a magnificent $100 a month. I went home and talked to my parents, who consented to let me play, and I signed. It was early June, and Minor League teams had been in operation since May. I packed my bag and went down to Union Station and bought my ticket for Erwin, Tennessee. Jack Sheehan had already advised Jim Poole, the Cubs manager in Erwin, when I would arrive and had assured me that I would be reimbursed for my fare. Since gloves were not used in Chicago Windy City Softball, it was necessary for me to purchase a glove. Baseball gloves, during this period, were not oversized and in the form of first basemen's mitts as they are today. My glove was small and did not have any form of connection between the fingers. Upon my arrival, Jim met me at the station and asked if I had any preferences as to where I would like to room. I said as long as it was clean, I didn't care. He took me to a little old cottage, just down the main street in town, and introduced me to the owner. The owner proceeded to tell me the room rent would be $2.50 every two weeks and I would be sharing the room and double bed with someone else. That someone happened to be a left-handed pitcher by the name of Ed Van Nordheim, from Lincoln, Nebraska, a nice enough guy, except that I soon learned he passed wind more than anyone I ever knew-especially at night in bed. Jim Poole told me they had a game that night and I was to report to the ballpark clubhouse for an early-afternoon workout prior to the game. Jim was a former Major League first baseman who played a short time with the Philadelphia Athletics from 1925 to 1927. He also played a number of years in the Minor Leagues. His nickname was Easy. However, I soon found out he would not be easy with me. When Ed and I got ready to go to the ballpark, I put my spikes, glove, jockstrap, sanitary socks, and T-shirt in my bag, and we took off. Well, the park was something to see! The old Works Progress Administration had cut this diamond out of the side of a mountain, and the left-field wall happened to be part of the mountain. The infield was hard clay, with no grass. The lights, if you can call them that, would have to go a long way to compare with those I played under in my Windy City softball days in Chicago. …

Archaeological Investigation of an Oil Well Pad Disturbance at the Tom Moore Site (41PN149), Panola County, Texas

The Tom Moore site (41PN149) is situated on the east slope of a circular-shaped landform at the highest point of a steeply-sloping upland in the Irons Bayou valley in Panola County, Texas. Irons Bayou, 1.2 km to the west of the site, flows east to its confluence with the Sabine River. A small tributary of Irons Bayou is 600 m to the south. Soils here are a brown sandy loam overlying a very hard red clay B-horizon. Like most of East Texas, the land has been farmed previously, as indicated by old plow furrows, and it has reforested naturally in pine and mixed hardwoods in the last 30 years. The site's upland setting is similar to other Middle Caddoan sites in the Sabine River basin in East Texas. An oil field employee, J. W. Golden of Kilgore, Texas, located the Tom Moore site. He noticed a cache of seven large celts that had been disturbed by construction equipment preparing a well site. The oil well construction consisted of two wells and three associated storage tanks. Approximately 2 acres had been disturbed during the leveling process, and part of the hill was used to form the level well pad. A cultural resources management survey had not been required by the Railroad Commission of Texas prior to construction. Mr. Golden described the celts as occurring in a group with the blade ends up. The heavy equipment had grazed them and caused some damage. He collected the celts and informed the authors. We visited the site, made a surface collection, noted a midden area at one end of the disturbance, and collected soil samples for flotation (these materials were submitted to S. Eileen Goldborer of Paleoethnobotanical Services, Austin, Texas) as well as OCR dates. No testing was conducted by the authors to determine the extent of the site. A small, circular mound is located in the wooded area adjacent to the well pad.

Porosity influence on the shear strength of granular material–clay mixtures

Materials forming part of rock fill dams, glacial tills, mudflows, debris flows, solifluction sheets, residual and colluvial soil deposits have a distinct structure, consisting of a mixture of large particles (gravel or hard clay fragments) and a soft matrix of clay. In order to analyze the stability of slopes made of granular material–clay mixtures, a measure of their shear strength is needed. Laboratory tests on these types of mixtures have indicated that their shear strength will depend upon the relative concentrations of the large particles and the clay. If the percentage by weight of the granular material in the granular material–clay mixture was >75%, the shear strength of the mixture was basically that of the granular material alone. When the concentration by weight of the granular material in the mixtures was <40%, the shear strength of the mixtures was basically that of the clay that surrounded the granular material. For the case in which the percentage of the granular materials in the solids mixture was between 40 and 75%, the shear strength of the mixtures was partially controlled by the granular phase. To date, no explanation has been put forward to account for why these limits of granular material in the mixtures exist at which it either controls, partially controls or has no control at all on the shear strength of the mixtures. This study presents an explanation for the existence of these limits. This explanation is based upon the resulting porosity of the mixtures.

Predesign Foundation Load Test Program for US-17 (Wilmington) Bypass over Northeast Cape Fear River

The North Carolina Department of Transportation is currently conducting a predesign foundation load test for a new bridge over the Northeast Cape Fear River near Wilmington, North Carolina. The primary purpose of the load test program is to determine whether concrete piles can penetrate a very dense and cemented sand layer and what side friction and tip bearing capacities should be used for the design of the drilled piers. Significant cost savings could be realized if pile foundations instead of drilled piers could support the approach spans of the bridge. For this determination, three concrete piles will be installed 30 m into the ground. Significant cost savings could also be realized by making a more accurate determination of the drilled pier capacities. For this determination, the side friction and tip bearing capacities of the dense Peedee sands and the underlying hard marine clays will be determined with Osterberg cell tests on two 2130-mm-diameter drilled piers. The different subsurface layers (muck, alluvial sands, and Peedee sands) will also be tested laterally with both static and statnamic testing to assist in the foundation design. The load test program incorporates an NCHRP research program on pile groups. The program includes testing a reusable instrumented steel pile group and frame at various sites in various soil conditions around the United States. The load test program results to date, the effect of the results on the foundation design, and the construction, testing, and instrumentation of the drilled piers are described.

Bonding between epoxidized natural rubber and clay in presence of silane coupling agent

Based on the results of bound-rubber determination, Monsanto rheometric studies, solvent swelling, measurement of physical properties, and infrared spectroscopic studies, it is revealed that epoxidized natural rubber (ENR) and hard clay interact chemically to form Si–O–C bond during high-temperature (180°C) molding. It is also observed that addition of the silane coupling agent N-3-(N-vinyl benzyl amino)ethyl-γ-amino propyl trimethoxy silane monohydrogen chloride enhances the extent of the chemical interaction with the formation of coupling bonds of Si–O–Si type between clay and the coupling agent and C–N bonds between ENR and the coupling agent. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1895–1903, 1999

Point Bearing Capacity of Non-Displacement Piles in Hard Clay

This paper discusses the factors used to determine the point bearing capacity of non-displacement piles in hard clay, and proposes a new approach based on a failure mechanism for estimating settlement of a non-displacement pile with tip in hard clay. Model tests were performed in which void ratios as well as undrained shear strength, confining pressure, pile diameters and settlement rates were adopted as the factors determining the point bearing capacity of non-displacement piles in hard clay. The results of the model tests led to the following conclusions.: (1) The point bearing pressure-settlement behavior can be divided into three phases. In the first phase, it is linear elastic and can be expressed by the elastic solution for a rigid punch. In the second phase, the hard clay under the pile tip failed in punching shear and in the third phase, it is practically defined to be ultimate; (2) Void ratio as well as undrained shear strength is one of the factors determining the point bearing capacity because it seriously affects point bearing capacity in the second and third phases. Point bearing capacity doesn’t vary significantly however with confining pressure, pile diameters and settlement rates; and (3) The proposed approach for estimating the settlement of the tip of a non-displacement pile in hard clay is generally consistent with the results of the model tests.

State of Miners' Health in Germany

Abstract Underground mining has a long tradition in Germany. While the mineral royalty created the basis for government mining inspectorates in the Middle Ages, the medical care of the miners and their families is also documented as early as 1225 in the Iglau Mining Act. In the last 20 to 30 years, iron ore mining has stopped in western Germany; only hard coal, salt, potassium, and clay are still mined underground, in addition to some isolated mining of rare minerals. The main activity consists of hard coal mining, with 100,000 miners underground in the Saar and Ruhr coalfields. In eastern Germany, uranium mining employed approximately 400,000 to 600,000 miners between 1945 and 1990. These mines are no longer active, but the high incidence of lung cancer in this mining population calls for specific medical supervision and care. The former copper mines of the Mansfeld area in eastern Germany have created similar health problems for the miners involved. The medical care of all German miners is regulated by ...

Design Method for Drilled Shafts in Soft Argillaceous Rock

A simple, rational method for predicting load-movement behavior of axially loaded drilled shafts in argillaceous intermediate geomaterials (hard clays and soft rocks) is presented. The method is based on a parametric finite element study that is described in detail in a companion paper. The method emphasizes the importance of the value of initial concrete pressure and roughness of the borehole. A numerical example is presented, and four diverse case histories are summarized that illustrate applications of the method to realistic geological and construction situations. Parameters that are included in the method include geomaterial compressive strength and modulus, borehole roughness, borehole smear, concrete pressure in the socket, and angle of sliding friction at the interface. The method is applicable to cohesive intermediate geomaterials that exhibit drained (c= 0) interface behavior, which can be assumed to be nonporous, argillaceous (clay-based) hard soil and soft rock.