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101.
Xin Li Dongliang Wang Baoquan Liu Chunling Ren Jianying Guo Xuefeng Su Jian Wang 《中国地球化学学报》2008,27(4):412-419
The northern margin of the Qaidam Basin is one of the main oil-gas exploration areas in western China, where source rocks are composed mostly of Middle and Lower Jurassic dark mud shale, carbargillite and coal. A large number of subsurface and outcrop samples differing in lithology with different types of organic matter were selected for resource evaluation, research and calculation. And among them, 13 samples were used for simulation experiment on hydrocarbon generating potential of various source rocks. At first, two kinds of heating modes were compared through simulation experiment, including single temperature-step heating and continual heating. Perhaps, the process of hydrocarbon generation and expulsion occurred naturally between a close system and an open system. In addition, the first heating mode was convenient, and all its reaction products were involved in the whole thermal evolution, and the final simulation experimental results were basically in consistency with the natural evolution trend Therefore, the first heating mode was adopted and the hydrocarbon yield of every sample was worked out. According to the type and lithology of organic matter and the hydrocarbon yield of samples for simulation experiment, hydrocarbon generation and expulsion mode with three kinds of lithology and five types of source rock has been established to provide the basis for hydrocarbon generation evaluation, research and resource calculation. 相似文献
102.
根据考虑几何和材料非线性及温度沿杆件截面高度线性分布等因素对钢结构常温和高温响应影响的基本方程,用自行编制的计算程序对单层双跨钢框架进行结构非线性温度响应研究,分析了弯曲应变、屈强比、梁柱刚度比、初始弹性模量等因素对结构响应的影响,并研究了温度步长、保护层厚度对结构耐火时间的影响。由计算结果发现,弯曲应变、初始弹性模量、梁柱线刚度比对梁跨中挠度及边柱柱顶水平位移影响较大,而对柱顶竖向位移影响不明显;当结构有防火保护层时,时间步长对结构耐火时间的影响不大,而保护层厚度对结构耐火时间的影响较明显。 相似文献
103.
Tritium concentrations were measured in a survey of 24 lakes, 15 wetlands, and 133 groundwaters in the oil sands region of northeastern Alberta and compared with both recent precipitation and precipitation sampled during the 1960s tritium peak caused by atmospheric thermonuclear weapons testing. Water samples from lakes included a group of 14 thaw lakes that had higher runoff attributed to melting of permafrost in peat plateaus within their watersheds. While tritium in all lakes was found to be intermediate between recent and 1960s concentrations, the thaw lakes were found to be significantly enriched in tritium compared with other lakes, as were unfrozen wetlands characterized by a thick sequence of low‐hydraulic conductivity peat. The results provide further evidence of different water sources to the thaw lakes and may indicate that melting of modern permafrost in part formed since the 1950s is occurring in these systems. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
104.
通过对我国建筑结构用钢在拉伸和压缩两种方式下的恒载升温试验,进行了5次受拉试件和2次受压试件的对比研究,根据试验中材料的各自变形规律,对其破坏机理进行了理论分析;从材料屈服的定义出发,给出了恒载升温拉伸试验中的参数(对应温度下的临界荷载水平),并与恒载升温压缩试验中的参数项进行了对比,指出受压构件和受拉构件的高温屈服强度是不同的,因此在钢结构建筑的耐火设计中应分别取不同的安全系数。 相似文献
105.
Michiaki Sugita Akihiro Matsuno Rushdi M. M. El-Kilani Ahmed Abdel-Fattah M. A. Mahmoud 《水文科学杂志》2017,62(10):1618-1635
Eddy correlation measurements within the Nile Delta allowed the determination of evapotranspiration (E) for seven crops (rice, maize, cotton, sugar beet, berseem, wheat and fava beans) using basin irrigation (BI), furrow irrigation (FI), BI with increased intervals (BIi), FI with increased intervals (FIi), strip irrigation (SI) and drip irrigation (DI). Total E values over the cropping season for rice (BI, BIi) were the highest (>600 mm), while those for sugar beet (DI), maize (SI and DI) and berseem (BIi) were the lowest (<250 mm). The differences were due to a combination of atmospheric demand, soil moisture, the presence of surface standing water, root depth, and the length and timing of the cropping season. The DI and SI methods had the advantage for water saving, while the FIi and BIi methods were effective for crops with shallow root lengths. Estimated annual E was 566–828 mm/year (water-saving irrigation) and 875–1225 mm/year (conventional irrigation). 相似文献
106.
Effects of different spatial distributions of physical soil crusts on runoff and erosion on the Loess Plateau in China 总被引:1,自引:0,他引:1 下载免费PDF全文
The response of runoff and erosion to soil crusts has been extensively investigated in recent decades. However, there have been few attempts to look at the effects of spatial configuration of different soil crusts on erosion processes. Here we investigated the effects of different spatial distributions of physical soil crusts on runoff and erosion in the semi‐arid Loess Plateau region. Soil boxes (1.5 m long × 0.2 m wide) were set to a slope of 17.6% (10°) and simulated rainfall of 120 mm h?1 (60 minutes). The runoff generation and erosion rates were determined for three crust area ratios (depositional crust for 20%, 33%, and 50% of the total slope) and five spatial distribution patterns (depositional crust on the lower, lower‐middle, middle, mid‐upper, and upper slope) of soil crusts. The reduction in sediment loss (‘sediment reduction’) was calculated to evaluate the effects of different spatial distributions of soil crusts on erosion. Sediment yield was influenced by the area ratio and spatial position of different soil crusts. The runoff rate reached a steady state after an initial trend of unsteadily increasing with increasing rainfall duration. Sediment yield was controlled by detachment limitation and then transport limitation under rainfall. The shifting time of erosion from a transport to detachment‐limiting regime decreased with increasing area of depositional crust. No significant differences were observed in the total runoff among treatments, while the total sediment yield varied under different spatial distributions. At the same area ratio, total sediment yield was the largest when the depositional crust was on the upper slope, and it was smallest when the crust was deposited on the lower slope. The sediment reduction of structural crust (42.5–66.5%) was greater than that of depositional crust (16.7–34.3%). These results provide a mechanistic understanding of how different spatial distributions of soil crusts affect runoff and sediment production. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
107.
108.
A new elastoplastic model called loading memory surface based on the critical state concept and the multi‐surface framework is proposed for geomaterials. The model uses a hypoelastic formulation and two plastic mechanisms. The formulations of the model are made in three‐dimensional stress–strain space and work under both monotonic and cyclic loadings. A newly introduced formalism makes it possible to obtain the cyclic response directly from the monotonic loading one. This formalism gives a three‐dimensional generalization of the well‐known Masing rule. The model has been validated against test results of Hostun sand under several conditions: monotonic and cyclic, drained and undrained, tests in compression and in extension, and at different confining pressures and different densities. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
109.
常德市水文地质及电测深、电测井的资料反映了孔隙水含水层涌水量的大小与含水层厚度、颗粒组分及其结构的多因素的复杂组合──—厚度(M)与视电阻率(ρ_s)的乘积密切相关,据此可预测单井涌水量。 相似文献
110.
Edge loaded annular foundations have been analysed assuming the soil pressure at the contact to be non-uniform using the lower bound approach of Limit Analysis. Variable fixity at the edges has been allowed and the foundation slab is made to follow the Square yield criterion. Results presented in the form of curves can be readily used to obtain the locations of the yield hinge circles for the given slab and the corresponding collapse load. © 1997 John Wiley & Sons, Ltd. 相似文献