共查询到20条相似文献，搜索用时 325 毫秒
1.
Xiaoqing Chen Kai Hu Jiangang Chen Wanyu Zhao 《Geotechnical and Geological Engineering》2018,36(2):885-896
Wide-grading gravelly soils are often encountered in debris flow source areas. To perform stability analyses under rainfall conditions, the soil–water characteristic curves (SWCC) are significant. However, the studies for SWCC of wide-grading gravelly soils are rare. In order to investigate the effects of initial dry density and grain size distribution on the SWCCs of wide-grading gravelly, a large-scale osmotic column, allowing the measurement of both volumetric water content and matric suction at various levels, was fabricated for a series of osmotic column tests. The test data were best-fitted to Van Genuchten equation using a least-squares algorithm and found that both the initial dry density and grain size distribution had a greater effect on the SWCCs. An increase in the initial dry density resulted in an increase in water retention capacity. The air entry value and residual volumetric water content increased linearly with increases in the initial dry density, whereas the maximum slope of SWCC decreased linearly with increases in the initial dry density. The air entry value and residual volumetric water content increased linearly with increases in the fine content (particle diameter <0.075), whereas the maximum slope increases linearly with increases in the effective size, d 10. 相似文献
2.
The factor of human projectactivity is often the immediate cause resulting in soil and water loss． The Baoji-Lanzhou second railway inconstruction is an example．The soil and water loss law caused by earth and stone mountain railway engineering construction in the northwestern China is studied systematically and that caused possibly by the road bed project，the road moat project，the field project，the tunnel project and the service road project inconstruction is probed．At the same time，the type，the intensity and influencing factor of soil and water loss in the northwest mountain railway construction are also studied． 相似文献
3.
Xinqing LEE Daikuan HUANG Wei JIANG Zhaodong FENG Hongguang CHENG Qian JIANG 《中国地球化学学报》2006,25(B08):278-278
Water samples from the Wujiang River, a typical karst river system, were analyzed for major ion concentrations and δ^34S values of dissolved sulfate in order to identify the sources of sulfate, quantify the sulfate export flux and understand the role of sulfur cycling in chemical weathering rate of carbonate. Spatial variations in sulfate concentration and sulfur isotopic composition of tributaries over the catchment area are obvious, allowing to decipher S sources between rocks and atmosphere. According to the variations in sulfate concentration and isotopic composition, it is inferred that sulfate ions in the upper-reach river waters may have three sources, rain water, sulfate resultant from oxidation of pyrite in coal, and sulfate from sulfide deposits. In the lower reaches, the S isotopic composition of the samples lies mainly on a mixing trend between evaporite sulfate and rainwater sulfate, the contribution of sulfate from oxidation of pyrite being lesser. A pronounced seasonal variation in both content and isotopic composition of sulfate characterizes the Wujiang River. The average sulfate concentration of the waters is 0.65 mmol/L in winter, 0.17 mmol/L higher than that in summer. River water δ^34S values range from -15.7‰ to 18.9‰ in winter, while the δ^34S values of river waters in summer vary to a lesser extent than in winter, from -11.5‰ to 8.3‰. The δ^34S values of the main stream range from -6.7‰ to -3.9‰ in summer, averaging 3‰ lower than in winter. This indicates that in summer, when the discharge increases, the contribution of a source enriched in light isotopes to the atmosphere or the oxidation of pyrite in coal is more important. 相似文献
4.
The factor of human project activity is often the immediate cause resulting in soil and water loss. The Baoji-Lanzhou second railway in construction is an example. The soil and water loss law caused by earth and stone mountain railway engineering construction in the northwestern China is studied systematically and that caused possibly by the road bed project, the road moat project, the field project, the tunnel project and the service road project in construction is probed. At the same time, the type, the intensity and influencing factor of soil and water loss in the northwest mountain railway construction are also studied. 相似文献
5.
6.
Doklady Earth Sciences - The content of polycyclic aromatic hydrocarbons (PAHs) in soil and snow cover near the carbon black plants in Moscow, Omsk, and Samara regions was studied. The differences... 相似文献
7.
This study aims to determine and to model the relationship of matric suction versus water content, known as soil?Cwater characteristic curve (SWCC), for a tropical soil profile at the southeastern Brazil. This soil profile consists of a colluvial, lateritic silty clay, with thickness of about 6.5?m. The filter paper and pressure plate techniques were used to determine the SWCC. Specimens were trimmed from the undisturbed soil samples collected along soil profile depth and submitted to drying paths. Impregnated thin-layer plates and a petrographic microscope were used to examine the structure and mineralogical composition of the soil samples. Mercury intrusion porosimetry tests were performed on some soil samples to obtain the frequency histogram of the pores. SWCC with bimodal pore-size distribution were obtained by the filter paper technique and SWCC with unimodal pore-size distribution were obtained by the pressure plate technique. The SWCC showed values of air-entry ranging from 1 to 3?kPa, depending on the technique used, resembling soils with macroporosity, as the lateritic soils. Combining both techniques, the SWCC could be fitted by a model that takes into consideration soils with macro and microporosity. 相似文献
8.
The effects of rate of strain on strength and deformation characteristics of soil–lime were investigated. Five strain rates (0.1, 0.8, 2.0, 4.0 and 7.0 %/min), five lime contents (0, 3, 6, 9 and 12 %) by dry soil weight and three cell pressures (100, 200 and 340 kN/m2) were carried. Triaxial tests, under unconsolidated condition, were used to study the effect of strain rate on strength and initial modulus of elasticity of soil and soil–lime mixture after two curing periods 7 and 21 days, respectively. A total of 405 triaxial specimens have been tested, where 225 specimens have been tested with first curing period (7 days). The testing program includes nine specimens for each strain rate, and each lime content was carried out, including natural soil with zero lime content. Another set of triaxial tests with a total of 180 specimens for the second curing period (21 days) was prepared at optimum moisture content, and the corresponding maximum dry density was also tested. The effects of strain rate and curing period on each of stress–strain behavior, type of failure, deviator stress at failure, cohesion and angle of internal friction and initial modulus of elasticity were studied thoroughly for the natural soil as well as soil–lime mixtures. For natural soil, the test results showed that the undrained shear strength, the initial modulus of elasticity and the cohesion increase significantly as the strain rate increase, while for soil–lime mixture at different curing periods, the undrained shear strength, initial modulus of elasticity and the cohesion increases to a maximum and then decreases as the strain rate and lime content increase. Also, the same variables and angle of internal friction increase with increasing curing period. 相似文献
9.
A residential building in Guilin City, China, underwent an up-and-down vibration with an amplitude of 2 cm. By eliminating several causes such as earthquake, wind and construction, in combination with the unique karst geological conditions of Guilin, it was inferred that the effect of turbulent karst water is the main contributor to the occurrence of this vibration. Therefore, a geophysical survey was undertaken on the vibration zone and its surroundings. The resutls suggest that the soil in the upper part of the karst grooves shows conspicuous traces of disturbance and the water content has low resistance. A comprehensive analysis indicates that there is a karst strong runoff zone beneath the area. According to the water level and water temperature data collected automatically by the instrument, it can be concluded that the groundwater level had changed significantly twice during this period, so it was determined that the denudation of groundwater strong runoff causes the overlying soil layer to collapse, forming a soil-water soft-flow material with mixed phase. Since the building in this area was supported by friction piles, the groundwater-soil soft-flow material with mixed phase has intense plasticity, and the up-and-down vibration resulted in the change of the friction piles, which caused the up-and-down vibration of the building structure. 相似文献
10.
At present, nearly 100 million tonnes of fly ash is being generated annually in India posing serious health and environmental problems. To control these problems, the most commonly used method is addition of fly ash as a stabilizing agent usually used in combination with soils. In the present study, high-calcium (ASTM Class C—Neyveli fly) and low-calcium (ASTM Class F—Badarpur fly ash) fly ashes in different proportions by weight (10, 20, 40, 60 and 80 %) were added to a highly expansive soil [known as black cotton (BC) soil] from India. Laboratory tests involved determination of physical properties, compaction characteristics and swell potential. The test results show that the consistency limits, compaction characteristics and swelling potential of expansive soil–fly ash mixtures are significantly modified and improved. It is seen that 40 % fly ash content is the optimum quantity to improve the plasticity characteristics of BC soil. The fly ashes exhibit low dry unit weight compared to BC soil. With the addition of fly ash to BC soil the maximum dry unit weight (γdmax) of the soil–fly ash mixtures decreases with increase in optimum moisture content (OMC), which can be mainly attributed to the improvement in gradation of the fly ash. It is also observed that 10 % of Neyveli fly ash is the optimum amount required to minimize the swell potential compared to 40 % of Badarpur fly ash. Therefore, the main objective of the study was to study the effect of fly ashes on the physical, compaction, and swelling potential of BC soils, and bulk utilization of industrial waste by-product without adversely affecting the environment. 相似文献
11.
Hang Lin Wenwen Zhong Hu Wang Wanzhong Xu 《Geotechnical and Geological Engineering》2017,35(6):2715-2726
Rainfall infiltration is the main factor that causes slope instability. To study the effect of hydraulic parameters on the final saturation line and stability of slopes, a numerical slope model is established with a saturated–unsaturated seepage analysis method. Analysis results show the following, (1) When parameter a increases, the effective rainfall duration decreases linearly, and the ultimate safety factor increases gradually; when parameter m increases, the effective rainfall duration increases linearly, and the ultimate safety factor decreases linearly; when parameter n increases, both the effective rainfall duration and the ultimate safety factor decrease first and then remain stable. (2) When the saturated permeability coefficient decreases, the effective rainfall duration presents a crescent trend, and the ultimate safety factor decreases first and then remains the same after rainfall intensity exceeds the saturated permeability coefficient of soil. (3) When rainfall intensity is less than the saturated permeability coefficient of soil, the location of the final saturation line rises as the saturated permeability coefficient decreases and is thus independent of parameters a, m, and n. 相似文献
12.
Acta Geotechnica - This paper presents an experimental investigation of the soil water retention curve (SWRC) and volume change curve over a large suction range (0–286.7 MPa), and... 相似文献
13.
Szegvi J sef Prokisch Per Marth Ba Kov s Zolt Gyi 《中国地球化学学报》2006,25(B08):195-195
The Soil Information and Monitoring System （TIM） is an independent subsystem of the integrated Environmental Information and Monitoring System in Hungary. Based on physiographical-soil-ecological units 1202 representative observation points were selected and exactly defined by geographical coordinates using GPS. The first sampling was done in 1992. Some soil parameters are measured every year, some others every 3 years or every 6 years depending on their changeability （stability）. Toxic element, heavy metal and rare earth element contents in soil samples were determined after hot and strong acid digestion by ICP-OES equipment. The rare earth elements were measured in TIM soil samples and some of them can be found in a relatively high amount, e.g. cerium and neodymium concentration are 3-4 times higher than the very often-measured copper concentration. Close correlation was found among some of the rare earth element concentrations. The Y-Yb correlation is the strongest, its r-value is higher than 0.95. The reason of difference among the yttrium concentrations of samples is not the deviation of ICP-OES measurement that is much smaller than the difference among the individual soil samples. Similar, close correlation was obtained between the soil yttrium and chromium concentration. The amount of chromium contamination can be calculated as the distance from the Y-Cr trend line. We call this method yttrium normalization. The principle of this method is described as follows： such elements than chromium and yttrium insist in the soil in a strongly bonded form. Therefore, in a non-contaminated area there is a close correlation between the yttrium and chromium concentrations. If the measured chromium concentration in a sample is not on the Cr-Y trend line than the distance it indicates the amount of antropogenic chromium. Contamination can be detected in that case of course if the contaminant does not contain yttrium. 相似文献
14.
Jagadish Kundu Kripamoy Sarkar P. K. Singh T. N. Singh 《Journal of the Geological Society of India》2018,91(4):418-424
This paper deals with the soil slope stability analysis along the road section (National Highway-05) near Luhri area, Himachal Pradesh, India. The area constantly experiences local as well as regional slides which enhances the siltation, reduce carrying capacity of the Sutlej river with time and further increases the water level on the banks of the slope. High traffic congestion puts the area at high risk zone and therefore, stability analysis was done using probabilistic as well as deterministic approach under static conditions through limit equilibrium method (LEM) and finite element method (FEM). FEM was used for stability analysis, mainly to obtain deformational characteristics, under static conditions and compared with LEM results. The results of both the methods help in identifying the zones of vulnerability in the case study. Further, the values of safety factor obtained from both the methods are in close approximation. The study also reveals that the slope is critically stable and a remedial measure has been suggested by modifying the geometry of the slope, which needs proper protection from any external factors like rainfall and earthquakes that may cause unforeseeable circumstances. 相似文献
15.
A total of 31 topsoil samples were systematically collected from the Panzhihuaminingarea including steel smelting,coal mining ,urban and rural districts.A normalization procedure was adopted to establish the environmental geochemical baseline models for this area.By using the above baseline models,the regional geochemical baseline values of As,Cr,Cu,Ni,Pb and Zn were determined.On the basis of the baselines,the enrichment factors were used to analyze the mechanism of trace metal pollution in topsoil from anthropogenic sources,and the results showed that the serious trace metal pollution is caused by human activities in coal mine,iron mine,smelting factory,tailing dam and other industrial districts in the Panzhihua area. 相似文献
16.
Guan Shaozeng 《《地质学报》英文版》1989,63(3):281-296
Since the coexistence of the Cretaceous and Palaeocene was ascertained in the Hengyang Basin of Hunan in the middle of the 1960's, the Cretaceous and Tertiary boundary has been discussed in several papers, but it still remains controversal. The points at issue are the connotation, stratigraphical position and lateral correlation of the Dongtang (or Chejiang) Formation. 相似文献
17.
The paper deals with the metallogenic conditions and regularities of the region ol the lower-middle reachesof the Changjiang River in China. The complicated structural network with the Changjiang (Yangtse) deepfracture as its trunk is the leading rock-and ore-controlling structure of the metallogenic belt. Thehigh-potassium granodiorites of the first magmatic sequence of the Mesozoic Yangtse syntexis type and thesodium-rich diorites of the second sequence are genetically related to the copper ore series and the iron ore se-ries respectively. and occur respectively in the block-faulted and-folded uplift area and the down-faulted vol-canic basin as well as the transitional zone between the two. The ore-hosting horizons show specific associa-tions of rocks and often contain ore beds basically of stratabound nature. 相似文献
18.
A simple mechanical model explaining the long-period (about 100-year) variations in the Earth’s rotational velocity is proposed. This model takes into account the gravitational interaction of the mantle with the solid core of the Earth and the fact that the core rotation leads that of the mantle. Well-known Earth parameters provide estimates of the gravitational torque that support the proposed model. The mathematical problem involved reduces to the classical problem of a nonlinear oscillator exposed to a constant torque. The well-known parameters of the core-mantle system result in a stable equilibrium and a stable limiting cycle on the phase cylinder of this oscillator. This equilibrium corresponds to a single angular velocity for the mantle and solid core, with no long-period oscillations in the length of the day. The limiting cycle corresponds to the core rotation leading the mantle rotation. In this case, the ellipsoidality of the gravitationally interacting bodies provides a periodic interchange of kinetic angular momentum between the mantle and solid core that results in long-period variations in the length of the day. The proposed model does not support the formerly widespread opinion that the core rotates more slowly than the mantle. 相似文献
19.
Zykina V. S. Zykin V. S. Volvakh N. Ye. Volvakh A. O. Murray A. S. Taratunina N. A. Kurbanov R. N. 《Doklady Earth Sciences》2021,500(2):870-874
Doklady Earth Sciences - We have analyzed the modern status of the chronostratigraphic differentiation of the loess–paleosoil series in southwestern Siberia and the results of luminescence... 相似文献
20.
Chronostratigraphy and Stratigraphic Classification of the Cretaceous of the Songliao Basin 总被引：3，自引：0，他引：3
Wang Pujun Du Xiaodi Wang Jun Wang Dongpo Geoenergy Department Changchun University of Earth Sciences Changchun Jilin Earth Sciences Department Nanjing University Nanjing Jiangsu 《《地质学报》英文版》1996,70(2):207-218
Isotopic ages of synsedimentary clay minerals were directly determined with the ultrasonicscattering-settlement separation-K-Ar dilution technique. The apparent age of black mudstoneis 123 Ma for the Quantou Formation, 111.9-89.0 Ma for the Qingshankou Formation and77.6-76.8 Ma for the upper part of the Nenjiang Formation. The Rb-Sr isochrone age of themuddy limestone-mudstone sequence of the lower part of the Nenjiang Formation is 81 Ma andthat of the muddy evaporite of the middle part of the Quantou Formation is 122.2 Ma. On thebasis of the above isotopic ages, the authors propose a modified scheme of stratigraphic classifi-cation of the Cretaceous of the Songliao basin. 相似文献