The freeze-thaw cycling process considerably changes the composition, structure, and properties of soils. Since the grain size is the most important factor in determining soil characteristics, our current research pri...The freeze-thaw cycling process considerably changes the composition, structure, and properties of soils. Since the grain size is the most important factor in determining soil characteristics, our current research primarily aims to investigate dynamic changes of the soil fraction when exposed to freeze-thaw conditions. We observed two series of Moscow morainic clayey specimens (gQⅡm): (Ⅰ) the original series, and (Ⅱ) the remolded series. We subjected each series of soil specimens to different frequencies of freeze-thaw cycles (3, 6, 20, and 40 cycles), and we used granulometric tests to analyze both series before and after exposure to freeze-thaw conditions. As a result of our experiments, the granulometric compositions tended to be distributed evenly after 40 freeze-thaw processes (i.e., content of fraction for 0.1-0.05 mm was increased after 40 freeze-thaw cycles) because the division of coarse grains and the aggregation of fine grains were synchronized during the freeze-thaw process. The soil grains in both series changed bi-directionally. In the original series, changes of the sand grains were conjugated with the clay grains, and in the remolded series, changes of the sand grains were conjugated with the silt grains, because potential energy difference caused the division and aggregation processes to relate to the counteraction process. The even distribution of soil grain size indicated the state of equilibrium or balance. The granulometric compositions were altered the most during the sixth freeze-thaw cycle, because the coefficient of the intensity variation of the grain fineness (Kvar) had its maximum value at that time.展开更多
Rajmahal trap along with its Inter-trappean sedimentary rocks is found exposed in the eastern part of India (24°00'E - 25°15'N;87°20'E - 87°15'E). Ten representative samples of Inte...Rajmahal trap along with its Inter-trappean sedimentary rocks is found exposed in the eastern part of India (24°00'E - 25°15'N;87°20'E - 87°15'E). Ten representative samples of Inter-trappean sandstone selected from the study area have been subjected to granulometric analysis. The result of the grain size analysis indicates that these sandstone specimens are very fine to fine grained with unimodal grain size distribution. They are dominantly fine skewed and generally mesokurtic in nature. The linear discriminant function plots of various grain size parameters suggest that these sandstones appear to have been deposited either in shallow marine or lacustrine environment. On multigroup multivariate discriminant functions V1 - V2 diagram majority of the samples fall in the beach depositional environment, indicating that most of the sediments were reworked by wave processes before deposition. The C-M pattern diagram shows that the sediment deposition took place in beach environment by rolling or suspension of sediments;hence the clastics were deposited in low energy condition.展开更多
The role of number of grain size fractions on structural and mechanical properties of uniaxially com- pressed granular packings with a uniform particle size distribution in terms of number of particles and with variou...The role of number of grain size fractions on structural and mechanical properties of uniaxially com- pressed granular packings with a uniform particle size distribution in terms of number of particles and with various particle size dispersities was studied using the discrete element method. The study addressed packing density, coordination number, contact forces, global stress, and energy dissipation in assemblies composed of frictional spheres. Packing density was found to change with increasing num- ber of granulometric fractions in mixtures with a small ratio of the diameters of the largest to smallest particles. Results indicated a certain value of particle size ratio below which the number of particle size fractions strongly affected packing density. The average coordination number decreased with increasing number of fractions. Detailed analysis of the effect of particle size dispersity on mechanical coordination number, including particles with no less than four contacts, revealed that, contrary to the average coordi- nation number, the mechanical coordination number increased with increasing ratio of the diameters of the largest to smallest particles in the sample. The composition of polydisperse samples strongly affected stress distribution and energy dissipation in granular packings.展开更多
The study area lies in the subaqueous delta, which came into being in 1964 - 1976. Oneoil-field road has been built for exploring petroleum to form a wave barrier. The hydrodynarnic conditions on the north side of the...The study area lies in the subaqueous delta, which came into being in 1964 - 1976. Oneoil-field road has been built for exploring petroleum to form a wave barrier. The hydrodynarnic conditions on the north side of the road are relatively violent, on the contrary the hydrodynarnic conditions on the south side of the road are nearly placid. This makes the study area a natural laboratory for studying the influence of the hydrodynarnic conditions on the fractal characteristics of the tidal flat. Selecting an area is named Case Ⅰ on the side of stronger hydrodynarnic activities and an area is named Case Ⅱ on the other side. Measuring the topography and sampling and analyzing the granulometrical composition, it is found that the hydrodynarnic conditions have fatal influence on the surface fractal dimensions and the granulometrical fractal dimensions of the area. In Case Ⅰ , which has strong hydrodynarnic conditions, the surface fractal dimensions are obviously larger than those of Case Ⅱ , and the granulometrical fractal dimensions are relatively smaller than those of Case Ⅱ , the surface fractal dimensions of Case Ⅰ decrease quickly with the increase of grid size; the granulometrical fractal dimensions are disperse, while the hydrodynarnic conditions of Case Ⅱ are just reverse. A sampling line and a core sampling on each side of the road are selected. It is found that on the south side of the road the granulometrical fractal dimensions vary regularly in the line and with the depth, the farther apart from the road, the smaller the fractal dimensions, and the deeper the sampling position the larger the fractal dimensions, while granulometrical fractal dimensions on the north side of the road have no such regularity pattern. The mechanism of the influence of the hydrodynarnic conditions on the fractal characteristics is discussed.展开更多
Based on the log-normal distribution of the grain size density function derived earlier for the entire zone of mineral disintegration, a unified granulometric taxon of perennially frozen soils is proposed which genera...Based on the log-normal distribution of the grain size density function derived earlier for the entire zone of mineral disintegration, a unified granulometric taxon of perennially frozen soils is proposed which generalizes the existing soil classifications.展开更多
The distribution, optically stimulated luminescence dating and granulometric properties suggest that the loess on the northern flank of Tian Shan should be divided into two types. One which is like mantle and is named...The distribution, optically stimulated luminescence dating and granulometric properties suggest that the loess on the northern flank of Tian Shan should be divided into two types. One which is like mantle and is named type A, is located on the windward slopes and dated to about 54.5±5.73 Ka. The other, called type B, lies flatly on the terraces of the rivers or low hills and penetrated 30.8±2.05 Ka ago. Here we study the origin and the age of two types of loess, and a model of loess formation is proposed. The dust was entrained from the Gobi Desert located to the north of Tian Shan by the monsoon from Mongolia, obstructed by the high mountains and deposited on the windward slopes of the mountains. The rivers and flows then transported the aeolian loess to low terraces and piedmont alluvial plains.展开更多
Granulometric analysis of Ngrayong sandstone samples from Rembang area of NE Java (Indonesia) has been carried out to examine the textural characteristics and elucidate depositional environment. The result data from t...Granulometric analysis of Ngrayong sandstone samples from Rembang area of NE Java (Indonesia) has been carried out to examine the textural characteristics and elucidate depositional environment. The result data from the grain size analysis indicates that the Ngrayong sediments are classified as sand or muddy sands. They are very fine- to medium-grained (phi values: 1.67 to 3.35), moderately- to well-sorted (standard deviation: 0.19 to 0.57), strongly fine-skewed to strongly coarse-skewed (skewness values: 4.82 to −5.97), and very platykurtic to very leptokurtic (kurtosis values: 0.36 to 2.41). Sandstone samples show unimodal grain size distribution. The sediments are interpreted to be transported in all three modes-traction, saltation and suspension, however, suspension and rolling are the major processes during transportation. Discriminant functions indicate diversity in the depositional environment for the sandstones. However, shallow marine is regarded as the dominant depositional environment. The preponderance of fine-grained sediments and lack of coarse sands suggest low to moderate energy conditions during deposition of Ngrayong sediments.展开更多
The Ouladine lagoon has an irregular bottom lined with different substrates. The lithological characteristics make it possible to observe sediments ranging from silts to sands and mixed sediments of variable color. Th...The Ouladine lagoon has an irregular bottom lined with different substrates. The lithological characteristics make it possible to observe sediments ranging from silts to sands and mixed sediments of variable color. These different fractions have varying proportions. The coarse fraction (>63 μm) has percentages ranging from 0 to 77% and the fine fraction ( μm) from 22.46 to 100% in the different sediments collected. The minority fraction of fine sands occupies the northern banks where the greatest depths of the section parallel to the coastal strip are observed. On the other hand, the sandy fractions occupy the southern shore up to the vicinity of the Azuretti mangrove island. This sandy fraction is also present on almost the entire section from the Comoé-Ebrié lagoon confluence to the closed mouth. The grain size characters of the sediments, such as the diagram of the classification coefficient So and the mean Mz, show well-classified sands. These sediments are deposited in a slightly agitated environment coming mainly from dunes and rivers. The sands of the estuarine complex were emplaced by saltation for most samples and by rotation.展开更多
<span style="font-family:Verdana;">In this study, the possibility of using corn cobs as an organic aggregate in producing lightweight concrete ha</span><span style="font-family:Verdana;&q...<span style="font-family:Verdana;">In this study, the possibility of using corn cobs as an organic aggregate in producing lightweight concrete ha</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> been investigated. First, some important physical properties of corn cob have been determined in the laboratory. These properties are as follows: weight to volume ratio (unit weight), water absorption rate and granulometric analysis. Later on, 4 concrete mixtures have been prepared according to </span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">workability of concrete and standar</span><span style="font-family:Verdana;">d</span><span style="font-family:;" "=""><span style="font-family:Verdana;">s specified in Turkey. After that, unit weight, heat transmissibility coefficient and 28-day pressure strength of these 4 concrete samples have been determined using machines measuring these properties. The 28-day pressure endurance value has been found between 1.4 - 56.25 kgf/cm</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">,</span></span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">heat transmissibility coefficient ha</span><span style="font-family:Verdana;">s</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> been found between 0.19 - 0.35 Kcal/m<span style="white-space:nowrap;">∙</span></span><span style="font-family:Verdana;">h<span style="white-space:nowrap;">∙</span><span style="white-space:nowrap;">˚</span>C and unit weight of samples have been found between 800 - 1520 kg/m</span><sup><span style="font-family:Verdana;">3</span></sup><span style="font-family:Verdana;">. Lastly</span></span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> these properties of concrete samples have been compared with other lightweight materials being used in </span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">construction of buildings.</span>展开更多
基金supported in part by the National Natural Science Foundation of China(No.41301070)the West Light Program for Talent Cultivation of Chinese Academy of Sciencesthe project sponsored by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry,which granted to Dr.Ze Zhang
文摘The freeze-thaw cycling process considerably changes the composition, structure, and properties of soils. Since the grain size is the most important factor in determining soil characteristics, our current research primarily aims to investigate dynamic changes of the soil fraction when exposed to freeze-thaw conditions. We observed two series of Moscow morainic clayey specimens (gQⅡm): (Ⅰ) the original series, and (Ⅱ) the remolded series. We subjected each series of soil specimens to different frequencies of freeze-thaw cycles (3, 6, 20, and 40 cycles), and we used granulometric tests to analyze both series before and after exposure to freeze-thaw conditions. As a result of our experiments, the granulometric compositions tended to be distributed evenly after 40 freeze-thaw processes (i.e., content of fraction for 0.1-0.05 mm was increased after 40 freeze-thaw cycles) because the division of coarse grains and the aggregation of fine grains were synchronized during the freeze-thaw process. The soil grains in both series changed bi-directionally. In the original series, changes of the sand grains were conjugated with the clay grains, and in the remolded series, changes of the sand grains were conjugated with the silt grains, because potential energy difference caused the division and aggregation processes to relate to the counteraction process. The even distribution of soil grain size indicated the state of equilibrium or balance. The granulometric compositions were altered the most during the sixth freeze-thaw cycle, because the coefficient of the intensity variation of the grain fineness (Kvar) had its maximum value at that time.
文摘Rajmahal trap along with its Inter-trappean sedimentary rocks is found exposed in the eastern part of India (24°00'E - 25°15'N;87°20'E - 87°15'E). Ten representative samples of Inter-trappean sandstone selected from the study area have been subjected to granulometric analysis. The result of the grain size analysis indicates that these sandstone specimens are very fine to fine grained with unimodal grain size distribution. They are dominantly fine skewed and generally mesokurtic in nature. The linear discriminant function plots of various grain size parameters suggest that these sandstones appear to have been deposited either in shallow marine or lacustrine environment. On multigroup multivariate discriminant functions V1 - V2 diagram majority of the samples fall in the beach depositional environment, indicating that most of the sediments were reworked by wave processes before deposition. The C-M pattern diagram shows that the sediment deposition took place in beach environment by rolling or suspension of sediments;hence the clastics were deposited in low energy condition.
文摘The role of number of grain size fractions on structural and mechanical properties of uniaxially com- pressed granular packings with a uniform particle size distribution in terms of number of particles and with various particle size dispersities was studied using the discrete element method. The study addressed packing density, coordination number, contact forces, global stress, and energy dissipation in assemblies composed of frictional spheres. Packing density was found to change with increasing num- ber of granulometric fractions in mixtures with a small ratio of the diameters of the largest to smallest particles. Results indicated a certain value of particle size ratio below which the number of particle size fractions strongly affected packing density. The average coordination number decreased with increasing number of fractions. Detailed analysis of the effect of particle size dispersity on mechanical coordination number, including particles with no less than four contacts, revealed that, contrary to the average coordi- nation number, the mechanical coordination number increased with increasing ratio of the diameters of the largest to smallest particles in the sample. The composition of polydisperse samples strongly affected stress distribution and energy dissipation in granular packings.
基金This study was supported by the National Natural Science Foundation Project of China under contract No. 141720888the Natural Science Foundation Project of Shandong Province under contract No. Q99E10.
文摘The study area lies in the subaqueous delta, which came into being in 1964 - 1976. Oneoil-field road has been built for exploring petroleum to form a wave barrier. The hydrodynarnic conditions on the north side of the road are relatively violent, on the contrary the hydrodynarnic conditions on the south side of the road are nearly placid. This makes the study area a natural laboratory for studying the influence of the hydrodynarnic conditions on the fractal characteristics of the tidal flat. Selecting an area is named Case Ⅰ on the side of stronger hydrodynarnic activities and an area is named Case Ⅱ on the other side. Measuring the topography and sampling and analyzing the granulometrical composition, it is found that the hydrodynarnic conditions have fatal influence on the surface fractal dimensions and the granulometrical fractal dimensions of the area. In Case Ⅰ , which has strong hydrodynarnic conditions, the surface fractal dimensions are obviously larger than those of Case Ⅱ , and the granulometrical fractal dimensions are relatively smaller than those of Case Ⅱ , the surface fractal dimensions of Case Ⅰ decrease quickly with the increase of grid size; the granulometrical fractal dimensions are disperse, while the hydrodynarnic conditions of Case Ⅱ are just reverse. A sampling line and a core sampling on each side of the road are selected. It is found that on the south side of the road the granulometrical fractal dimensions vary regularly in the line and with the depth, the farther apart from the road, the smaller the fractal dimensions, and the deeper the sampling position the larger the fractal dimensions, while granulometrical fractal dimensions on the north side of the road have no such regularity pattern. The mechanism of the influence of the hydrodynarnic conditions on the fractal characteristics is discussed.
文摘Based on the log-normal distribution of the grain size density function derived earlier for the entire zone of mineral disintegration, a unified granulometric taxon of perennially frozen soils is proposed which generalizes the existing soil classifications.
基金sponsored by the National Key Basic Research Program of China(2007CB411305) to Z.J.Guo
文摘The distribution, optically stimulated luminescence dating and granulometric properties suggest that the loess on the northern flank of Tian Shan should be divided into two types. One which is like mantle and is named type A, is located on the windward slopes and dated to about 54.5±5.73 Ka. The other, called type B, lies flatly on the terraces of the rivers or low hills and penetrated 30.8±2.05 Ka ago. Here we study the origin and the age of two types of loess, and a model of loess formation is proposed. The dust was entrained from the Gobi Desert located to the north of Tian Shan by the monsoon from Mongolia, obstructed by the high mountains and deposited on the windward slopes of the mountains. The rivers and flows then transported the aeolian loess to low terraces and piedmont alluvial plains.
文摘Granulometric analysis of Ngrayong sandstone samples from Rembang area of NE Java (Indonesia) has been carried out to examine the textural characteristics and elucidate depositional environment. The result data from the grain size analysis indicates that the Ngrayong sediments are classified as sand or muddy sands. They are very fine- to medium-grained (phi values: 1.67 to 3.35), moderately- to well-sorted (standard deviation: 0.19 to 0.57), strongly fine-skewed to strongly coarse-skewed (skewness values: 4.82 to −5.97), and very platykurtic to very leptokurtic (kurtosis values: 0.36 to 2.41). Sandstone samples show unimodal grain size distribution. The sediments are interpreted to be transported in all three modes-traction, saltation and suspension, however, suspension and rolling are the major processes during transportation. Discriminant functions indicate diversity in the depositional environment for the sandstones. However, shallow marine is regarded as the dominant depositional environment. The preponderance of fine-grained sediments and lack of coarse sands suggest low to moderate energy conditions during deposition of Ngrayong sediments.
文摘The Ouladine lagoon has an irregular bottom lined with different substrates. The lithological characteristics make it possible to observe sediments ranging from silts to sands and mixed sediments of variable color. These different fractions have varying proportions. The coarse fraction (>63 μm) has percentages ranging from 0 to 77% and the fine fraction ( μm) from 22.46 to 100% in the different sediments collected. The minority fraction of fine sands occupies the northern banks where the greatest depths of the section parallel to the coastal strip are observed. On the other hand, the sandy fractions occupy the southern shore up to the vicinity of the Azuretti mangrove island. This sandy fraction is also present on almost the entire section from the Comoé-Ebrié lagoon confluence to the closed mouth. The grain size characters of the sediments, such as the diagram of the classification coefficient So and the mean Mz, show well-classified sands. These sediments are deposited in a slightly agitated environment coming mainly from dunes and rivers. The sands of the estuarine complex were emplaced by saltation for most samples and by rotation.
文摘<span style="font-family:Verdana;">In this study, the possibility of using corn cobs as an organic aggregate in producing lightweight concrete ha</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> been investigated. First, some important physical properties of corn cob have been determined in the laboratory. These properties are as follows: weight to volume ratio (unit weight), water absorption rate and granulometric analysis. Later on, 4 concrete mixtures have been prepared according to </span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">workability of concrete and standar</span><span style="font-family:Verdana;">d</span><span style="font-family:;" "=""><span style="font-family:Verdana;">s specified in Turkey. After that, unit weight, heat transmissibility coefficient and 28-day pressure strength of these 4 concrete samples have been determined using machines measuring these properties. The 28-day pressure endurance value has been found between 1.4 - 56.25 kgf/cm</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">,</span></span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">heat transmissibility coefficient ha</span><span style="font-family:Verdana;">s</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> been found between 0.19 - 0.35 Kcal/m<span style="white-space:nowrap;">∙</span></span><span style="font-family:Verdana;">h<span style="white-space:nowrap;">∙</span><span style="white-space:nowrap;">˚</span>C and unit weight of samples have been found between 800 - 1520 kg/m</span><sup><span style="font-family:Verdana;">3</span></sup><span style="font-family:Verdana;">. Lastly</span></span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> these properties of concrete samples have been compared with other lightweight materials being used in </span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">construction of buildings.</span>