无纺土工织物保土应用中的概率设计准则   总被引：1，自引：0，他引：1  

佘巍  陈轮  王钊 《岩土力学》2007,28(10):2052-2054

保土准则是土工织物反滤准则的重要组成部分,但目前的设计准则保土有余,透水不足。介绍了无纺土工织物的两种孔洞分布曲线,计算了土颗粒透过织物的概率。在理论分析的基础上,提出了一种概率保土准则。该准则对土体中的骨架颗粒和小颗粒透过织物的概率分别加以限制,既能保持土体稳定,又能防止淤堵。  相似文献   

Integral equation solution for three-dimensional heat transfer in multiple-fracture enhanced geothermal reservoirs     

Dong Dong Liu  Yan Yong Xiang  Jin Lei Zheng 《国际地质力学数值与分析法杂志》2020,44(11):1511-1524

For the prediction of energy production from multiple-fractured geothermal reservoirs, previous models basically focused on the one-dimensional conduction in the rock containing evenly distributed fractures of equal scale. Here, a novel model is described to numerically investigate the three-dimensional heat transfer in geothermal reservoirs with unevenly spaced disc fractures of various sizes including the aperture and radius. In terms of the water flow through each fracture, an approximate analytical solution is obtained on the assumption that the water pressure disturbances, induced by the fracture margin and extraction (injection) operation, at the injection (extraction) well center and at different locations within the injection (extraction) well range were approximately equal. By the integral equation scheme for two-dimensional planar fractures, the three-dimensional problem of heat exchange is simulated without the reservoir discretization. The singular integral is analytically calculated in polar coordinates whereas the nonsingular integrand is numerically estimated by the Gaussian quadrature method in Cartesian coordinates. Compared with the one-dimensional simplification, the three-dimensional heat conduction remarkably alters the prediction of extraction temperature. In addition, the reservoir temperature field is also significantly influenced by the spacings and dimensions of fractures. The present model may be used for the estimation, design, and optimization of a geothermal reservoir.  相似文献   

Shallow groundwater dynamics and its driving forces in extremely arid areas: a case study of the lower Heihe River in northwestern China          下载免费PDF全文

Ping Wang  Jingjie Yu  Sergey P. Pozdniakov  Sergey O. Grinevsky  Changming Liu 《水文研究》2014,28(3):1539-1553

Shallow groundwater is an important source of water for the maintenance and restoration of ecosystems in arid environments, which necessitates a deeper understanding of its complex spatial and temporal dynamics driven by hydrological processes. This study explores the dominant hydrological processes that control the shallow groundwater dynamics in the Gobi Desert‐riparian‐oasis system of the lower Heihe River, a typical arid inland river basin located in northwestern China. The groundwater level and temperature were monitored in 14 shallow wells at 30‐min intervals during the 2010–2012 period. After combining this information with meteorological and hydrological data, a comprehensive analysis was conducted to understand the dynamic behaviour of the shallow groundwater system and to determine the dominant factors that control the groundwater flow processes. The results of the study indicate notably large temporal and spatial variations in both the groundwater level and temperature. Noticeable fluctuations in the groundwater level (0.5–1 m) and temperature (4–8 °C) were observed in the riparian zone, evidencing a clear river influence. In comparison, the groundwater fluctuations in the Gobi Desert were more stable (the annual variations of the water table were less than 0.5 m, and the water temperature varied by no more than 2 °C). Strong variations in the groundwater table (1.5–5.0 m/year) and temperature (1.5–6.5 °C), mainly caused by surface flood irrigation and groundwater pumping, were observed in the oasis area. The investigated sites were categorized into three types that reflect the dominant hydrological processes: (1) the riparian zone, dominated by riverbank filtration and groundwater evapotranspiration; (2) the Gobi Desert area, controlled by groundwater evaporation and lateral recharge; and (3) the oasis area, dominated by groundwater evapotranspiration as well as surface–groundwater interactions caused by human activities. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

增强型地热系统:潜力大、开发难   总被引：1，自引：0，他引：1  

廖志杰  万天丰  张振国 《地学前缘》2015,22(1):335-344

文中讨论了为什么要开发干热岩地热资源?什么是干热岩系统和增强型地热系统?中国干热岩系统的潜力,如何发展中国的EGS以及我们可供考虑的建议。随着常规能源的不断消耗,可再生能源日益受到人类的青睐。在可再生能源中,地热能的容量最大,地热发电提供的是基本负荷,但是由于诸多因素,开发滞后。尤其是对潜力大、开发难的增强型地热系统,中国更是从研究到开发,都刚刚起步。如果地热发电的规模要超过风能及太阳能等其他新能源,不能仅靠水热型地热系统的开发利用,而必须重视和利用干热岩资源,大力研发增强型地热系统。中国干热岩系统的潜势如何呢?中国科学院地质地球物理研究所利用921个大地热流数据编制了《中国大陆地区新版热流图》以及3~10km深处不同深度温度分布图,计算了不同深度干热岩地热资源量,总数为2.09×107 EJ;其中主要分布在青藏高原,占全国总资源量的五分之一。作者们认为,干热岩资源的开发和增强型地热系统的建立是一个系统工程,地热资源的开发是一项风险投资,亚经济型的EGS风险更甚。国家必须统一安排和投资。工程项目必须学习国外的经验和吸取开发的教训。要选择关键地区进行试验和研究。作者们建议可考虑选择羊八井地热田的北部作为试验地区。  相似文献   

ICP-MS测定甘肃某农场大气颗粒物中的铬、铜、砷、镉、铅含量     

胡小耕  高永宏 《甘肃地质》2011,(3):89-92

空气滤膜吸附采集甘肃某农场大气粉尘样品,采用盐酸—硝酸—氢氟酸—高氯酸溶解,电感耦合等离子体质谱法（ICP-MS）同时测定溶液中铬、铜、砷、镉、铅等重金属元素含量,分析农田环境大气颗粒中的重金属元素对农作物的影响,同时验证不同仪器工作参数对测定结果的影响。实验表明：在选定的实验条件下,分析元素的检出限低,准确性和精密度...  相似文献   

天然河床渗滤取水工艺的原理与特点研究——以浠水南城水厂为例     

宋凯  李晓  吴方燕 《地下水》2011,(1):106-108

渗滤取水净水机理主要是利用砂砾石层表面的泥膜及砂砾石层本身过滤作用、吸附作用,微生物的降解作用达到去除水中的悬浮物质、降低水的浊度、除菌的效果。以湖北浠水南城水厂渗滤取水工程为例,通过对渗滤工程特点和水质监测数据的研究,分析天然河床渗滤水水质及水源水水质的差异,以及渗滤水水质的可靠度。  相似文献   

Purification and characterization of acetylcholinesterase from brain tissues of Oreochromis aurea and its application in environmental pesticide monitoring     

YunHua Ding  XiaoMin Wu  JunBin Fang 《寒旱区科学》2011,3(4):0339-0343

Acetylcholinesterase (AChE) plays an important role in enzyme-based detection of pesticides in the environment. In this paper, AChE from the Triton X-100 extract of brain tissues of Oreochromis aurea was purified by (NH₄)₂SO₄ fractional precipitation, Sephadex G-100 gel filtration, and DEAE-cellulose ion exchange chromatography. Certain biochemical characterizations of the purified enzyme and inhibition of pesticides on the enzyme were also studied. The specific activity of this purified enzyme was 20.628 U/mg protein, fold of purification was 139, and recovery was 22.1%. The optimal temperature of this enzyme was between 35–40 °C, and optimal pH was between 7.5–8.0. The Michaelis constant (K_m) for acetylthiocholine iodide was 0.183 mmol/L. The enzyme activity was inhibited by excess substrate, and optimal substrate concentration was 6 mmol/L. Four pesticides (dichlorvos, phoxim, triazophos, and methomyl) exhibited strong inhibitions on this enzyme with IC₅₀ less than 5 μg/mL. This study suggests that Oreochromis aurea (tilapia) could be a good enzyme source for pesticide monitoring in water environments.  相似文献   

Geothermal Power Generation Potential in the Eastern Linqing Depression     

KANG Fengxin  ZHAO Jichu  TAN Zhirong  SUI Haibo  SHI Meng 《《地质学报》英文版》2021,95(6):1870-1881

China has been the leading country worldwide in direct geothermal utilization for a rather long time, which has contributed significantly to reducing carbon emissions. But the installed capacity of geothermal power generation in China is very small, and there are only a few geothermal power plants in China, specifically in Tibet, including the well-known Yangbajing geothermal power plant. Therefore, it is anticipated that more high-temperature geothermal resources will be discovered in order to promote China’s power generation. There is potential for high-enthalpy geothermal in the Eastern Linqing Depression in Shandong Province, where geothermal energy is stored in Ordovician and Cambrian carbonate strata. Based on the geothermal gradient in Cenozoic strata and the depth of the target geothermal reservoir, the temperature distribution pattern of the reservoir was analyzed, and two “sweet points” were identified in the Yucheng geothermal field and the Guanxian geothermal field, where the reservoir temperature is predicted to be higher than 200°C at a depth of less than 8000 m. Due to the low karst fissure ratio and the insufficient geothermal fluid in the geothermal reservoir, it is recommended that an enhanced geothermal system be set up, to increase the permeability of the natural fracture system in the carbonate formations and provide sufficient fluid for power generation through reinjection of used geothermal fluid. The power generation capacity of the two geothermal fields was estimated using a volumetric method, revealing a power generation capacity of 1621.02 MWe for the Yucheng geothermal field, and 1287.19 MWe for the Guanxian geothermal field.  相似文献   

Thermo-economic Investigation of an Enhanced Geothermal System Organic Rankine Cycle and Combined Heating and Power System     

WANG Lingbao  BU Xianbiao  LI Huashan 《《地质学报》英文版》2021,95(6):1958-1966

As a potentially viable renewable energy, Enhanced Geothermal Systems (EGSs) extract heat from hot dry rock (HDR) reservoirs to produce electricity and heat, which promotes the progress towards carbon peaking and carbon neutralization. The main challenge for EGSs is to reduce the investment cost. In the present study, thermo-economic investigations of EGS projects are conducted. The effects of geofluid mass flow rate, wellhead temperature and loss rate on the thermo-economic performance of the EGS organic Rankine cycle (ORC) are studied. A performance comparison between EGS-ORC and the EGS combined heating and power system (CHP) is presented. Considering the CO2 emission reduction benefits, the influence of carbon emission trading price on the levelized cost of energy (LCOE) is also presented. It is indicated that the geofluid mass flow rate is a critical parameter in dictating the success of a project. Under the assumed typical working conditions, the LCOE of EGS-ORC and EGS-CHP systems are 24.72 and 16.1 cents/kWh, respectively. Compared with the EGS-ORC system, the LCOE of the EGS-CHP system is reduced by 35%. EGS-CHP systems have the potential to be economically viable in the future. With carbon emission trading prices of 12.76 USD/ton, the LCOE can be reduced by approximately 8.5%.  相似文献   

地下水曝气-砂滤处理产生的废弃石英砂中铁砷含量与形态分布     

张耀强  胡冰冰  谢世伟  袁松虎 《地学前缘》2021,28(5):208-214

高铁高砷地下水严重威胁饮水质量,曝气-砂滤法因处理效果好且成本低在农村地区得到广泛应用。砂滤过程石英砂表面富集铁和砷后需定期更换,然而废弃石英砂堆置具有砷释放风险。本文以江汉平原某水厂砂滤池废弃石英砂为研究对象,采用激光剥蚀-等离子体质谱(LA-ICP-MS)、拉曼光谱(Raman)、X射线衍射(XRD)和分步化学提取等手段,研究了砂样中的Fe和As含量及形态分布。结果表明,砂粒表面形成了一层厚度为20100 μm的高铁砷薄层,薄层内部Fe和As含量显著高于两侧,Fe和As分布高度相关(R²=0.985)。砂样表面铁矿物以无定型/弱结晶型为主,同时检出赤铁矿和臭葱石等矿物。砂样中Fe和As总含量分别为20.1 mg/g和53.4 μg/g。砂样表面铁主要以易溶解态、碳酸盐结合态和易还原态为主,As主要吸附在铁矿物上。研究区降雨充沛,当废弃石英砂遭遇雨水冲刷或淹没时,可能导致铁砷薄层中As解吸或随Fe矿物还原溶解而释放。  相似文献