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71.
逯向阳 《沉积与特提斯地质》2008,28(4):14-17
烃源岩有机质丰度的恢复具有重要的现实和理论意义。笔者在对比多种方法的基础上,对大民屯凹陷的烃源岩的有机质丰度进行了恢复。 相似文献
72.
山区公路工程建设对地下水渗流的影响 总被引:1,自引:0,他引:1
分别就公路路堤、路堑、半挖半填等路基结构和隧道结构对周围岩土体的渗透性、渗流路径、地下水位等方面的影响进行了分析,以对公路工程建设对地下水环境的影响和与水文地质有关的灾害和损害的分析评价有所帮助。 相似文献
73.
Cheng-Shin Jang Chen-Wuing Liu Yeeping Chia Li-Hsin Cheng You-Ching Chen 《Hydrogeology Journal》2008,16(2):389-397
Changes in hydrogeological properties of the River Choushui alluvial fan aquifer before and after the 1999 Chi-Chi earthquake, Taiwan, have been identified using pumping tests. Three wells, SH2, YL2 and SC2, located in a compressional zone with high coseismic groundwater levels, were tested. The threshold of the aquifer deformation with respect to transmissivity (T) is greater than that with respect to storage coefficient (S). Decreases in the post-earthquake S are approximately 60% at SH2 and SC2, indicating aquifer compression after the Chi-Chi earthquake. Changes in the post-earthquake T range from 61% increase to 0.8% decrease. Moreover, results from anisotropy analysis of T at SC2 further illustrate that normal stresses induced by the Chi-Chi earthquake have consolidated soil particles. Soil particles dilated laterally after the earthquake, resulting in an increase of the equivalent T. The changes in hydrogeological properties have a considerable influence on spatiotemporal fluid pressure and horizontal groundwater movement, resulting in different amounts of drawdown during post-earthquake pumping. 相似文献
74.
鱼耳石中锶和钡富集的影响因素及其环境响应 总被引:4,自引:1,他引:3
鱼耳石中元素锶和钡主要来源于鱼类生存的水体,这两种元素通过腮或肠进入内耳淋巴液,继而以类质同象的方式沉淀在耳石晶格内部空位和晶格间隙中。耳石结晶沉淀的整个过程不仅受生物的调控作用,而且还受到外界环境,如水体元素浓度、盐度、温度等因素的影响,因此耳石中某种元素的浓度与其在水体中的浓度之比(元素富集系数)与鱼类所生存的环境之间具有一定的响应关系。在以上各种因素中,水体元素浓度对耳石元素富集系数的影响最为显著。一般来说,耳石中某种元素的含量与水体中相应的元素浓度呈正相关关系,而水体中元素之间就耳石中的富集过程也存在一定的相互促进或抑制作用,如Sr对Ba为协同作用,Ca对Sr、Zn为拮抗作用。另外,水体盐度或温度与元素富集系数之间不存在简单的线性相关关系,而是因鱼种、水体综合环境及元素种类不同而有所差异。研究结果表明:鱼种一定的情况下,耳石中元素富集系数与水体盐度和温度存在良好相关关系。基于以上相关性分析,可以认为耳石中元素富集系数与环境因子(水体元素浓度、盐度、温度)之间存在响应关系。因此,可以选用那些受环境影响大但对自身调控影响小的元素(如:Sr、Zn、Pb、Mn、Ba、Fe、Li、Ni、Cd)来建立耳石与水体环境之间元素富集系数的定量化模型,并利用这种响应关系及定量化模型进行生态环境监测和渔业管理。 相似文献
75.
A. Bongartz S. Schweighoefer C. Roose U. Schurath 《Journal of Atmospheric Chemistry》1995,20(1):35-58
The mass accommodation coefficient of ammonia gas on water has been determined by measuring the absorption rate of 50–200 ppm NH3 in one atm of air or helium into a liquid jet of 97 µm diameter as function of the exposed jet length, and comparing the results with numerical simulations which treat as the only free parameter. The model considers in detail transport of NH3 by molecular diffusion, penetration of the gas/water interface, hydrolysis in the acidified water, and transport of the solutes from the surface into the jet. A correction is applied for the time evolution of the jet surface speed, using literature data on the fluid mechanics of liquid jets. The result of nine sets of independent measurements is
相似文献
76.
W. Kirchner F. Welter A. Bongartz J. Kames S. Schweighoefer U. Schurath 《Journal of Atmospheric Chemistry》1990,10(4):427-449
A liquid jet of 90 m diameter and variable length has been utilized to determine absorption rates and, hence, mass accommodation coefficients , of atmospheric trace gases. The compounds investigated are HCl (0.01), HNO3 (0.01), N2O5 (0.005), peroxyacetyl nitrate (>0.001), and HONO (0.005). It is concluded that the absorption of these trace gases by liquid atmospheric water is not significantly retarded by interfacial mass transport. The strengths and limitations of the liquid jet technique for measuring mass accommodation coefficients are explored. 相似文献
77.
Performance of Mortar and Chemical Grout Injection into Surrounding Soil When Slurry Pipe-jacking Method is Used 总被引:1,自引:0,他引:1
Hideki Shimada Takashi Sasaoka Saeid Khazaei Yasuhiro Yoshida Kikuo Matsui 《Geotechnical and Geological Engineering》2006,24(1):57-77
Small-diameter shallow tunnels are often being built by using the slurry pipe-jacking method. This system involves the pushing
or thrusting of a drivage machine and concrete pipes into the ground. Chemical grout injection into the surrounding soil around
the tunnel is carried out after the drivage and pushing processes are finished. The purpose of the chemical grout injection
is to maintain permanent stability of the surrounding soil. However, the behavior of the chemical grouting material in the
surrounding soil around the tunnel and the amount of optimum injection is not clearly understood. From these points of view,
this paper discusses the performance of the chemical grouting material, when it is injected into the surrounding soil around
the tunnel, by means of 2-D Eulerian–Lagrangian seepage analysis. Moreover, the effectiveness of the chemical grout injection
was evaluated by using the non-linear finite element method. This investigation show when the range of the grouted zone is
designed; it is necessary that the relationship between Young’s modulus of the soil/grouted zone and the confining stress
be taken into consideration in order to establish effective, economical and safe chemical grout injection system. Understanding
the performance of the seepage/dispersion behavior of the chemical grout and the characteristics of soil/ grouted zone is
also important. 相似文献
78.
Tingting Yao Craig Calvert Tom Jones Glen Bishop Yuan Ma Lincoln Foreman 《Mathematical Geology》2006,38(1):51-62
Spectral simulation has gained application in building geologic models due to the advantage of better honoring the spatial continuity of petrophysical properties, such as reservoir porosity and shale volume. Distinct from sequential simulation methods, spectral simulation is a global algorithm in the sense that a global density spectrum is calculated once and the inverse Fourier transform is performed on the Fourier coefficient also only once to generate a simulation realization. The generated realizations honor the spatial continuity structure globally over the whole field instead of only within a search neighborhood, as with sequential simulation algorithms. However, the disadvantage of global spectral simulation is that it traditionally cannot account for the local information such as the local continuity trends, which are often observed in reservoirs and hence are important to be accounted for in geologic models. This disadvantage has limited wider application of spectral simulation in building geologic models. In this paper, we present ways of conditioning geologic models to the relevant local information. To account for the local continuity trends, we first scale different frequency components of the original model with local-amplitude spectrum ratios that are specific to the local trend. The sum of these scaled frequency components renders a new model that displays the desired local continuity trend. The implementation details of this new method are discussed and examples are provided to illustrate the algorithm. 相似文献
79.
许多大坝的失事是由于高地下水位引起坝肩失稳所致。绕坝渗流是影响坝肩高地下水位的主要因素。为此通常将大坝基础防渗帷幕延伸到坝肩岸坡内一定距离,以减小绕坝渗流影响。而防渗帷幕运行性态随时间变化,为了评价坝肩防渗帷幕和地下水位的运行性态,首先分析了地下水位观测资料和水位、降水、温度、时效等时空影响因素及其表达式,随后基于岸坡地下水位观测资料,利用最小二乘法建立了大坝岸坡地下水位的时空分布模型。通过比较模型剩余标准差和测点的剩余标准差,可以确定坝肩地下水位的异常测点,分析岸坡防渗薄弱部位,掌握坝肩岸坡渗流场时空分布规律,监控绕坝渗流的性态。 相似文献
80.
为了对三峡工程二期高土石围堰防渗设施的布置方案及其阻渗效果进行比较,采用有限元法对二期高土石围堰在不利的运行工况下的渗流场进行数值分析.比较了双排混凝土防渗墙方案、单排塑性混凝土低防渗墙加土工膜斜墙和单排厚塑性混凝土防渗墙等3种方案,分别采用恒定与非恒定模型计算,对立面二维和三维绕渗及防渗墙局部开裂等不利工况分别进行了数值模拟.结果表明:三方案均可有效抑制渗流场,双排混凝土防渗墙的防渗效果最好;墙体的局部开裂仅对局部区域的流场有影响.非恒定数值分析表明,堰体、基础不均匀沙石料及基坑抽水速度对渗流场影响极大,为保证堰体稳定,应限制基坑水位降落速度小于2 m/d. 相似文献
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