SMALL SCALE PARALLEL FLOW CONTACT EROSION TEST BETWEEN SAND AND SILTY CLAY LAYERS

The historical evolution of an ancient forest that developed at Gaoyao, south China, can be divided into 4 stages of radiocarbon intervals (1.1–1.5, 2.0–3.5, 3.6–4.0, and 4.3–4.9 ka) in which the last 3 stages all developed in a wetland and formed humic layers of 2.0, 0.5, and 0.7 m depth, respectively. The humic layers were interrupted by 2 white-gray silty clay layers that most likely formed during climate fluctuations. Four drought events were identified during the evolution of the ancient forest, occurring around 4.3, 3.6, 2.0, and 1.1 ka, respectively, with durations of ∼1000 14C yr. These events are consistent with other records both in low- and high-latitude areas, in particular with the little ice ages occurring since the mid-Holocene. Precipitation likely increased from 5.0 to 3.6 ka in south China, then decreased, which is probably the main cause for the development as well as the demise of the ancient forest.

Download Full-text

Forming conditions of the Graikas lignite, N. Peloponnese

Bulletin of the Geological Society of Greece ◽

10.12681/bgsg.17183 ◽

2001 ◽

Vol 34 (3) ◽

pp. 1195 ◽

Cited By ~ 6

Author(s):

Σ. ΚΑΛΑΪΤΖΙΔΗΣ ◽

Σ. ΠΑΠΑΖΗΣΙΜΟΥ ◽

Κ. ΧΡΗΣΤΑΝΗΣ

Keyword(s):

Influence Factor ◽

Volatile Matter ◽

Low Rank ◽

Early Pleistocene ◽

Silty Clay ◽

Inorganic Matter ◽

Pyrite Content ◽

Marine Influence ◽

Clay Layers ◽

Coal Petrography

In Northern Péloponnèse (southern Greece) several lignite seams occur, many of which were exploited in the past decades. In the small Graikas basin, in the upland Aigialia, a 2.5-m-thick lignite seam outcrops within the Pliocene/ Pleistocene sediments. The pre-Neogene margins and the basement of the basin consist of radiolarites, pelagic limestones, and flysch of the Pindos isopic zone. The sediments filling the basin include marly, sandy and clay layers, which deposited under marine, brackish and lacustrine conditions, during the rifting of the Corinth graben (Late Pliocene-Early Pleistocene). The seam consists of lignite and clay-rich lignite layers, of matrix lithotype, with total thickness of 1.4 m, intercalating with thin marly, silty, clay and humic clay layers. Fourteen lignite samples were obtained for proximate and ultimate analyses and coal-petrography studies. The ash contents of the Graikas lignite range up to 46.2% on dry base revealing intense inorganic input. The total sulphur contents are also high up to 4%. The fixed carbon and volatile matter contents (33.2-46% and 53.9-66.8% on daf, respectively), as well as the H/C and O/C atomic ratios and the reflectance of Eu-ulminite Β (Rm 0.26-0.30%), indicate a low rank (soft brown coal, Weichbraunkohle). Micropetrographic studies revealed a Huminite content >73%, Liptinite <23%, and Inertinite <12%. Attrinite and Densinite are the most prevailing macérais, while Texto-ulminite A and Eu-ulminite A show moderate values. Inertodetrinite and Semi-fusinite dominate within the Inertinite macerai group. Cutinite and Liptodetrinite are the most abundant macérais of the Liptinite group. Mainly clay and carbonate minerals constitute the inorganic matter (7-30%). However, pyrite content is also significantly high, up to 10%, revealing anoxic marine influence. Factor analysis suggests that peat accumulation started under anoxic conditions and intense bacterial activity. The peat-forming vegetation was mostly herbaceous with minor contribution of arboreal vegetation. Moreover, negative correlation is revealed between the gelification degree and the inorganic input. Coal-facies diagrammes suggest low preservation of the organic tissues and highly scattered gelificationindeces. The peat in the Graikas basin started accumulating in a lagoonal environment under brackish conditions behind a barrier. Progressively, sea regraded and the conditions became limnic to limnotelmatic

Download Full-text

The interpretation and environmental significance of a buried Middle Pleistocene soil near Ipswich Airport, Suffolk, England

Philosophical Transactions of the Royal Society of London Series B Biological Sciences ◽

10.1098/rstb.1987.0067 ◽

1987 ◽

Vol 317 (1186) ◽

pp. 365-391 ◽

Cited By ~ 22

Keyword(s):

Land Surface ◽

Large Scale ◽

Mineral Weathering ◽

Middle Pleistocene ◽

Small Scale ◽

Minor Role ◽

Silty Clay ◽

Environmental Reconstruction ◽

Frozen Ground ◽

Fine Clay

A buried Middle Pleistocene soil at Ipswich Airport, Suffolk, England, was studied by using macromorphological, textural, mineralogical, chemical and micromorphological techniques. This soil, developed on a low-level terrace surface in the Kesgrave Sands and Gravels, and buried beneath solifluction deposits and the Barham Sands and Gravels, is a composite of the Valley Farm and Barham Soils which have been recognized over wide areas of East Anglia. Clay illuviation, gleying, rubification (haematite formation) and periglacial disruption were the major pedogenic processes active during its formation; mineral weathering and temperate pedoturbation appear to have played only a minor role. After deposition of the Kesgrave Sands and Gravels and establishment of a stable land surface, clay was translocated from the eluvial horizons into the lower illuvial horizons. Initially, this process consisted solely of fine clay but as the environment deteriorated, coarser and more poorly sorted clay was translocated. Biotic, shrink—swell or frost turbation processes led to localized disruption of some limpid (fine) clay coatings before, or simultaneous with, commencement of this phase of coarser clay illuviation. However, most fragmentation of coatings occurred later when the environment had deteriorated to one characterized by seasonally frozen ground. At this stage, silt grains were translocated and small-scale contraction cracks or microscale cryogenic features (silty clay cappings and duplex textural lamellae features) formed. Further deterioration of climate led to formation of large-scale contraction cracks and soil (or incipient ice) wedges, truncation of the soil and deposition of two solifluction deposits. The older sediment contains components of the eroded eluvial horizons, whereas the other solifluction deposit and the overlying (glacifluvial) Barham Sands and Gravels contain minerals derived from the Anglian ice sheet. The soil at Ipswich Airport is developed in the Waldringfield Member of the Kesgrave Formation, which is assumed to be of Beestonian age. As the overlying sediments were apparently deposited during the Anglian Stage, it appears that the soil probably formed during the Cromerian and early parts of the Anglian. Such a chronology would not be in dispute with the proposed environmental reconstruction derived largely from pedological evidence, which suggests a simple environmental deterioration from a temperate optimum to that of periglacial conditions. However, much depends on the significance of the first disruption phase. If the fragmentation of limpid clay coatings represents a sharp climatic oscillation, the environmental reconstruction and stratigraphic implications of this soil may be more complex.

Download Full-text

Flame propagation in a small-scale parallel flow

Combustion Theory and Modelling ◽

10.1080/13647830601173174 ◽

2007 ◽

Vol 11 (5) ◽

pp. 697-714 ◽

Cited By ~ 5

Author(s):

J. Daou ◽

P. Sparks

Keyword(s):

Flame Propagation ◽

Parallel Flow ◽

Small Scale

Download Full-text

Mineral Tanah sebagai Indikator Stabilitas Tanah pada Daerah Berlereng: Studi Kasus Tombolopao Kabupaten Gowa

Jurnal Ecosolum ◽

10.20956/ecosolum.v7i1.5214 ◽

2018 ◽

Vol 7 (1) ◽

pp. 33

Author(s):

Asmita Ahmad ◽

Christianto Lopulisa ◽

A.M Imran, ◽

Sumbangan Baja

Keyword(s):

Clay Minerals ◽

Soil Texture ◽

Clay Content ◽

Small Scale ◽

Soil Stability ◽

Silty Clay ◽

Soil Mineral ◽

Forming Process ◽

Soil Movement ◽

Physical And Chemical

Soil forming process can influence soil stability, especially on a sloping area, which is currently related to landslides. This research aims to study mineral content in the soil as an indicator to evaluate soil stability in slope area. Soil texture analyzed with hydrometer and soil mineral analyzed with Kerr method. Soil parent rock comes from Tpbv (Tertiary Pliocene Baturape Volcanic) Formation that consists of lava, breccia, tuff, and conglomerate. Soil texture in A horizon dominated with silty clay loam and in B horizon with silty clay. Clay content in A horizon to B horizon increase ranges from 2-6%. Soils mineral have been weathering on the physical and chemical, which caused cracking on minerals lattice and formed clay minerals inside it. The presence of clay minerals between soil mineral particles can cause mutual repulsion force and cause friction particles that triggering the movement of particles in a small scale when soil saturated by water and triggers soil movement (landslide).

Download Full-text

Seismites in the Kathmandu basin, Nepal

Journal of Nepal Geological Society ◽

10.3126/jngs.v18i0.32204 ◽

1998 ◽

Vol 18 ◽

Author(s):

A. P. Gajurel ◽

P. Huyghe ◽

C. France- Lanord ◽

J. L. Mugnier ◽

B. N. Upreti ◽

...

Keyword(s):

Sandy Loam ◽

Hanging Wall ◽

Coarse Sand ◽

Small Scale ◽

Seismic Events ◽

Silty Clay ◽

Lacustrine Deposits ◽

M Sequence ◽

Water Saturated ◽

Sandy Sediments

The Kathmandu valley is a large intermontane basin carried above the Himalayan major decollement. It is limited southward by the Mahabharat Range, which forms the hanging wall of the Mahabharat Thrust, and northward by the Shivapuri Range. The Kathmandu basin is filled with a very thick (500-600 m) sequence of fluvio-lacustrine Plio-Pleistocene sediments, which unconformably overlie the folded and faulted Precambrian-Palaeozoic Kathmandu Complex. These semi-consolidated deposits mainly consist of fine to coarse sand, sandy loam, sandy silty clay, and gravely conglomerate. New field data show that small-scale deformational structures occur in the lacustrine deposits of the central and southern parts of the Kathmandu basin. In Thimi section, these structures take place within sub horizontal clayey layers. They mainly consist of finely contorted and folded sandy layers which form balls and pillows of about 10-13cm thick. In a few places, the deformational structures are associated with small folds and micro-faults (normal and reverse faults), with micro-breccias and sand dykes. The convolute lamination structures show no preferential verging, thus, excluding shearing related to the influence of a palaeoslope. Such structures have been found in three different places and they were always confined to single stratigraphic horizons positioned between undisturbed parallel beds. The deformational structures described above show characteristics of seismites. The associated seismic events may be related to major earthquakes or movements along the active nearby faults. Earthquake-induced liquefaction and subtle variations in physiomechanical properties of water-saturated fine sandy sediments have probably controlled the deformational pattern.

Download Full-text

Effect of Rainfall Pattern and Crack on the Stability of a Red Bed Slope: A Case Study in Yunnan Province

Advances in Civil Engineering ◽

10.1155/2021/6658211 ◽

2021 ◽

Vol 2021 ◽

pp. 1-21

Author(s):

Zhenping Zhang ◽

Xiaodong Fu ◽

Qian Sheng ◽

Dawei Yin ◽

Yongqiang Zhou ◽

...

Keyword(s):

Plastic Zone ◽

Pore Water ◽

Yunnan Province ◽

Pore Water Pressure ◽

Limit Equilibrium ◽

Water Pressure ◽

Small Scale ◽

Silty Clay ◽

The Stability ◽

Red Bed

Red bed slopes in the southwest of China are associated with a grant number of geological hazards, such as landslides, mud-rock flows, and rock blocks falling, which are vital problems in geotechnical engineering. The damage can be induced or triggered due to a series of human and environmental activities, such as excavation, concentrated or long-term rainfall, earthquake, and fluctuation of groundwater level. According to the field observations and geological exploration results, a small-scale landslide was observed on January 10, 2016, after excavation along XiaoMo highway in Yunnan Province. A numerical model in actual size using GeoStudio software based on this typical red bed engineering slope was established in this study. Back analyses and laboratory tests were used to obtain the mechanical parameters of the geomaterial inside the slope. The historic rainfall data of Mengla County from July to September in 2016 was utilized as the flux boundary in analyzing the seepage variation features and the stability of the engineering slope in the rainy season. One major tension crack was set in the shallow region of the silty clay according to the geology survey to perform the disturbance of excavation on the geomorphology of the slope. Attempts were made to establish the anisotropic permeability of the crack induced by the complex fillings, and differences in the hydraulic response between the cracking and completed slope during the rainfall process were discussed. The result shows that the factor of safety of the slope without crack before the rainfall is 1.076, and the slope is considered in the state of the critical limit equilibrium, which is in accordance with the previous state of the slope under real conditions. The pore water pressure variations of the monitor points in the shallow region of the completed slope present close compliance with the rainfall intensity subjected to different rainfall patterns, which also controls the distribution of the plastic zone in the slope after rainfall. The comparisons in the seepage field and plastic zone between the cracking and completed slope reveal that the crack can shorten the infiltration path effectively, and the higher the permeability coefficient in the vertical direction is, the larger the pore water pressure increasing zone is and the higher the underground water level is, which should be paid more attention in highway constructions.

Download Full-text

Kaji efisiensi temperatur penukar panas dengan variasi aliran untuk aplikasi pengering

Jurnal POLIMESIN ◽

10.30811/jpl.v16i2.562 ◽

2018 ◽

Vol 16 (2) ◽

pp. 39

Author(s):

Syukran Syukran

Keyword(s):

Fluid Flow ◽

Heat Exchanger ◽

Heat Exchangers ◽

Cross Flow ◽

Fluid Phase ◽

Parallel Flow ◽

Small Scale ◽

Counter Flow ◽

Flow Type ◽

Temperature Efficiency

Abstrak Heat exchanger atau alat penukar panas adalah alat-alat yang digunakan untuk mengubah temperatur fluida atau mengubah fasa fluida dengan cara mempertukarkan panasnya dengan fluida lain. Pada sebuah penukar panas kemampuan mempertukarkan panas sangat ditentukan oleh tipe dan jenis aliran fluida yang melewati penukar panas. Secara garis besar penukar panas dibagi berdasarkan arah aliran fluidanya. Berdasarkan arah aliran fluida penukar panas dibedakan menjadi 3 (tiga) jenis aliran, yaitu aliran searah (parallel flow), aliran berlawanan (counter flow) dan aliran silang (cross flow). Saat ini penukar panas banyak dipakai dalam industri pengeringan produk-produk pertanian, perkebunan dan perikanan skala kecil dan menengah. Penggunaan penukar panas dalam bidang pengeringan saat ini sudah menjadi kebutuhan untuk mengatasi permasalahan produktifitas pengeringan. Umumnya penukar panas yang digunakan adalah tipe aliran berlawanan. Beberapa penelitian telah dilakukan untuk mengetahui efektifitas penukar panas tersebut yang umumnya berfokus pada jenis aliran berlawanan. Penelitian penelitian spesifik yang mengkaji perbandingan efisiensi penukar panas untuk ketiga jenis aliran belum ditemukan. Penelitian ini dilakukan untuk mengetahui efisiensi temperatur penukar panas untuk jenis aliran jenis aliran melintang, sejajar, dan berlawanan. Metode penelitian dilakukan fabrikasi 3 unit exchanger tipe gas-gas dengan dimensi 50 (P) x 10 (L) x 30 (T) dengan jumlah tube 17 susunan. Hasil penelitian menunjukkan bahwa efisiensi temperatur untuk ketiga jenis penukar panas tersebut adalah 21,3% aliran melintang, 17,3% aliran berlawanan dan 15,9% aliran sejajar. Hasil penelitian menyimpulkan bahwa efisiensi temperatur tertinggi diperoleh jenis penukar panas aliran melintang. Kata kunci : Penukar panas, aliran sejajar, aliran berlawanan, aliran silang, temperatur. Abstrack Heat exchangers or heat exchangers are the means used to change the temperature of the fluid or to change the fluid phase by exchanging heat with other fluids. In a heat exchanger the heat exchange ability is greatly determined by the type and type of fluid flow passing through the heat exchanger. Broadly speaking the exchanger is divided based on the direction of fluid flow. Based on the direction of fluid flow exchanger is divided into 3 (three) types of flow, namely parallel flow, counter flow and cross flow. Currently, heat exchangers are widely used in the drying industry of small and medium-sized agricultural and small-scale plantation and fishery products. The use of exchangers in the field of drying is now a need to overcome the problems of drying productivity. Generally the exchanger used is the opposite flow type (counter flow). Several studies have been conducted to determine the effectiveness of these exchangers which generally focus on the opposite type of flow. Specific research studies that reviewed the efficiency of exchangers for the three types of flow have not been found. This research was conducted to find out the efficiency of heat exchanger temperature for flow type of cross flow, parallel flow and counter flow type. The research method was fabricated 3 units of gas-gas exchanger type with dimension 50 (P) x 10 (L) x 30 (T) with the number of tubes 17 staggered arrangement. The results show that the temperature efficiency for the three types of heat exchanger is 21.3% cross flow flow, 17.3% flow counter flow and 15.9% parallel flow flow. The results concluded that the highest temperature efficiency obtained by cross flow flow type exchanger. Keywords: Heat exchanger, parallel flow, counter flow, cross flow, temperature

Download Full-text

Experimental study on mechanism for pumping-induced land subsidence

Proceedings of the International Association of Hydrological Sciences ◽

10.5194/piahs-382-387-2020 ◽

2020 ◽

Vol 382 ◽

pp. 387-390

Author(s):

Yun Zhang ◽

Guofeng He ◽

Jichun Wu ◽

Zhiduo Zhu ◽

Xuexin Yan ◽

...

Keyword(s):

Pore Water ◽

Model Test ◽

Land Subsidence ◽

Pore Water Pressure ◽

Water Pressure ◽

Physical Model Test ◽

Silty Clay ◽

Sand Layer ◽

Test Results ◽

Clay Layers

Abstract. Groundwater pumping can cause severe land subsidence, yet the mechanisms have not been completely clear. A laboratory physical model test was done to investigate the mechanism for pumping-induced land subsidence. In the model test, a model well was installed and pumpage through the well was taken. During and after pumping, the soil displacement and the pore water pressure were documented. The pore water pressure within the pumped sand layer decreased immediately after pumping and recovered immediately after stopping pumping, while the pore water pressure in the neighboring silty clay layers first increased and then decreased with pumping, and first decreased and then increased after pumping was stopped and groundwater level in the sand layer recovered. The duration within which the pore water pressure in the silty clay increased when pumping was increasingly great with the distance from the pumped sand layer. The compaction of the neighboring silty clay first occurred near the interface between the silty and sand layers, and the silty clay expanded vertically within some zones. The test results indicate that the mechanism for land subsidence is complex. Due to their low permeability, aquitard units may expand in a period when groundwater is withdrawn from the neighboring aquifer units, and they may compact when groundwater is recharged into the neighboring aquifer units. This is one of the reasons for the lagging compaction of aquitard units.

Download Full-text