Installation of a vertical slurry wall around an Italian quarry lake: complications arising and simulation of the effects on groundwater flow   总被引：1，自引：0，他引：1  

D. A. De Luca  M. Lasagna  A. Morelli di Popolo e Ticineto 《Environmental Geology》2007,53(1):177-189

Slurry walls are non-structural barriers that are constructed underground to impede groundwater flow or manage groundwater control problems. The study area is in the Piemonte plain (Italy), close to the River Po. Quarrying works carried out below the piezometric surface created two big quarry lakes. The local groundwater system is characterized by a lower semi-confined aquifer, which is overlain by a semi-permeable bed of clayey peat (aquitard) and an upper unconfined aquifer. Locally, the peat fades away and the granulometry of this horizon becomes silty sandy. A planned enlargement of the quarry will increase the size and depth of the quarry lakes. So the aquitard bed between the two aquifers will be damaged, creating a mixing rate of groundwater. Such a procedure would not be compatible with the presence of two municipal wells upstream from the quarries. Consequently, the installation of a vertical diaphragm (slurry wall) is recommended to separate the aquifers and to act as a filter for the groundwater flowing from the unconfined to the semi-confined aquifer. To predict the consequences caused by the installation of the vertical diaphragm separating the unconfined aquifer and the semi-confined one, a specifically adjusted finite-difference model was used. The model showed a maximum rising of the water table equal to 12 cm, just upstream of the diaphragm and for a distance of about 100 m, and a maximum lowering of 2 cm just downstream of the diaphragm. However, the slurry wall would not cause any change in the piezometric head in the area where there are municipal wells and, hence, will not have any negative effect on the functionality of the municipal wells. Moreover, the migration of water from the unconfined aquifer through the vertical diaphragm will stimulate a series of attenuation and auto-depuration processes of eventual contaminants. These processes are due to the higher crossing time that the groundwater flow takes to go through the vertical barrier (t _a = 96.5 days, whereas for the horizontal semi-permeable layer t _a = 9.6 days). So, the vertical diaphragm can be a resolutive element, representing a mediation and separation factor between the unconfined and the semi-confined aquifers along the border of the quarrying areas, and a protective barrier for the water quality of the quarry lake and the semi-confined aquifer.  相似文献   

高空急流入口区次级环流在一次突发性强降水过程中的作用     

覃庆第 《气象研究与应用》2001,22(4):20-22

通过对 1999年秋季一次突发性降水过程高空急流的分析 ,发现急流入口区南侧辐散 ,其低层辐合上升 ,当低层有印缅槽活动的时候 ,对流加强 ,印缅槽发展 ;急流入口区北侧辐合 ,其低层辐散下沉 ,有向南的非地转风  相似文献   

山东南墅地区孔兹岩系变质矿物的成因及演化   总被引：3，自引：0，他引：3  

周喜文  董永胜  魏存弟 《吉林大学学报(地球科学版)》2001,31(2):116-121

南墅地区孔兹岩系的变质矿物具有多成因、多世代的特征 ,其经历三阶段五幕的变质作用 ,形成了以Sil+Gt +Cord +Bi +Kf +Pl+Q为代表的共生矿物组合。通过对主要变质矿物成因及演化特征的分析 ,结合温压计估算 ,确定该区孔兹岩系峰期变质作用温度为 70 0～ 75 0℃ ,压力为 0 .6～0 .7GPa ,变质程度达角闪麻粒岩相。确立 pTt轨迹具顺时针演化特点 ,反映一种陆 -陆碰撞造山带式构造演化模式。  相似文献   

地地震多参数BP神经网络预测煤层厚度     

韩万林  张幼蒂  李梁 《煤田地质与勘探》2001,29(4):53-54

依据煤层反射波运动学和动力学特征，提取出了波峰波谷振幅A1、平均频率Fa、主频带能量Qf1、低频带宽能量Qf和峰值频率Fmain等5个地地震特征参数。选取8组学习样本，利用4层BP（Back Propagation)人工神经网络模型，采用动量法和自适应调整的改进算法，训练BP网络，用训练好的BP网络预测煤层厚度。经实例验证，地震多参数BP网络预测煤层厚度精度高，是一种有效的煤厚预测方法。  相似文献   

Ein Pollendiagramm aus dem Untergrund des Zürichsees     

Lüdi Von Werner  ZH Zollikon 《Aquatic Sciences - Research Across Boundaries》1957,19(2):523-564

Zusammenfassung Im Sommer 1952 wurden von Prof.Otto Jaag im Zürichsee cine Reihe von Tiefenbohrungen ausgeführt. Ein Bohrkern von 830 cm L?nge, der in 140 m Seetiefe entnommen worden war, wurde pollenanalytisch durchge-gearbeitet. Der See erreicht an dieser Stelle seine gr?sste Tiefe, und sein Boden ist auf einer Fl?che von 1000 m Breite und 7000 m L?nge ganz flach, was dafür Gew?hr bietet, dass die Sedimentation ungest?rt vor sich gehen konnte. Der Bohrkern bestand aus tonreichem Mergel oder unreiner Soekreide, mit einzelnen Einlagerungen von Sand (Abb. 2). Er reichte bis in die waldfreie Zeit des Sp?tglazials hinab. Die Ergebnisse der Pollenanalyse sind in den Abbildungen 2 und 3 zusammengestellt. In Abbildung 2, rechts aussen, wird versucht, die Ablagerung nach den Zeitstufen vonBlytt-Sernander undFranz Firbas zu gliedern. Dabei ergaben sich Schwierigkeiten, und es ist fraglich, ob die natürlichen Grenzen in unserm Diagramm mit der zeitlich festgelegten Periodeneinteilung der oben genannten Forscher immer in übereinstimmung gebracht werden k?nnen. Auch wenn die gleiche Waldfolge gefunden wird, so dürften die Waldzeiten im Alpenvorland teilweise wesentlich früher in Erscheinung getreten sein als weiter gegen Norden hin.

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Summary During the summer of 1952 several deep boring into the underground of the Zürich-see were carried out by Prof. Dr.O. Jaag. One boring core with a length of 830 cm obtained under 140 m lake water was carefully investigated by pollenanalysis. In the spot from where this core originated, the lake reaches its greatest depth and its bottom is entirely flat within an area of 1000 m to 7000 m, which guarantees that the sedimentary process could continue without disturbance. The boring core consisted of loamy marl or lake-lime (Seekreide) with very few sandy layers (Fig. 2). The eldest samples date from woodless late-glacial time. Results of pollenanalysis are summarized in Figures 2 and 3. In Figure 2 (right outside) it was tried to divide the deposit into time-periods according toBlytt-Sernander andF. Firbas. However there arose certain difficulties and it remains doubtful, whether the natural limits in our diagram agree in each case with the fixed periods of the above named authors. Even where the same sequence of forest-development is found it is likely that some of the same forestperiods were realized considerably earlier in the foreland of the Alps than in northernmore parts of Europe.

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Die vorliegende Studie bildet einen Bestandteil der von Prof. Dr.O. Jaag organisierten Sediment-Untersuchung im Zürichsee. Die Durchführung der Bohrungen, die im Jahre 1952 stattfanden, wurde erm?glicht dank grosszügiger finanzieller Unterstützung durch dieVolkart-Stiftung, Winterthur, durch dieKulturkommission der Gemeinde Zollikon ZH sowie durch dieBeh?rden der Stadt und des Kantons Zürich. Bisher wurde ver?ffentlicht:H. Züllig,Sedimente als Ausdruck des Zustandes eines Gew?ssers, Schweiz. Z. Hydrol.18 (1956).  相似文献   

Un procedimento per l'aggiustamento delle grandi triangolazioni     

Dr. Carlo di Bernasconi 《Pure and Applied Geophysics》1955,30(1):1-7

Riassunto In una nota diA. Marussi è stato rilevato che se, dopo aver compensato una triangolazione con le sole condizioni intrinseche, si impongono ulteriori condizioni come la coincidenza di alcuni vertici in punti prefissati, è possible determinare con sufficiente precisione le coordinate dei rimanenti vertici attraverso corrispondenze analitiche che soddisfino le condizioni di contorno e col requisito di limitare gli errori lineari e angolari. — L'Autore della presente nota propone una nuova corrispondenza, cioè quella atta a rappresentare le deformazioni di una membrana o rete elastica sottoposta ad assumere una data configurazione; stabilisce le equazioni per la rete elastica piana e sferica; mette in evidenza come il principio fisico della minima energia e quello matematico dei minimi quadrati conducano alle medesime equazioni.

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Summary A. Marussi has pointed out that if, after having compensated a triangulation with the intrinsic conditions only, we impose further conditions as the coincidence of some vertex in prefixed points, we can determinate the coordinates of the other vertex: that happens through analytical connections fulling contour conditions and limiting linear and angular errors.The present Author proposes a new connection, which is apt to represent the deformations of an elastic network which is to get a given configuration. He fixes the equations for the spherical and plane networks; points out how the physical principle of the least energy and the mathematical one of the least squares may give the same equations.

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Structural physical parameter identification based on evolutionary-simplex algorithm and structural dynamic response   总被引：1，自引：0，他引：1  

杜修力  曾迪 《地震工程与工程振动(英文版)》2003,2(2):225-236

Evolutionary computation based on the idea of biologic evolution is one type of global optimization algorithm that uses self-adaptation, self-organization and random searching to solve optimization problems. The evolutionary-simplex algorithm is introduced in this paper. It contains floating encoding which combines the evolutionary computation and the simplex algorithm to ovcrcomc the problems encountered in the genetic algorithm and evolutionary strategy methods.Numerical cxpcrimcnts arc performed using seven typical functions to verify the algorithm. An inverse analysis method to identify structural physical parameters based on incomplete dynamic responses obtained from the analysis in the time domain is prcscntcd by using the evolutionary-simplex algorithm. The modal evolutionary-simplex algorithm converted from the time domain to the modal domain is proposed to improve the inverse efficiency. Numerical calculations for a 50-DOF system show that whcn compared with other methods, the evolutionary-simplex algorithm offers advantages of high precision,cfficient searching ability, strong ability to resist noise, independence of initial value, and good adaptation to incomplete information conditions.  相似文献   

佛坪自然保护区植物群落物种多样性与海拔梯度的关系   总被引：35，自引：4，他引：31  

岳明  张林静  党高弟  辜天琪 《地理科学》2002,22(3):349-354

用多元统计分析方法研究了佛坪自然保护区植物群落多种性及群落各生长型多样性特征沿海拔梯度的变化。结果表明：1）植物群落的Shannon指数与Simpson指数及物种丰富度与海拔梯度均呈显著负相关关系;2）乔木层的物种多样性沿海拔梯度的变化则体现了“中国高度膨胀”的规律,即中等海拔高度上多样性高而低海拔和高海拔多样性较低;3）灌木层丰富度指数在1600-1700m之间有个很不明显的峰值,而其它4个指标沿海拔呈单调的下降趋势;4）草本层植物多样性呈先降后升的趋势,在中等海拔高度较低。  相似文献   

Neogene and quaternary volcanism of the Bijar Area (Western Iran)     

M. Boccaletti  F. Innocenti  P. Manetti  R. Mazzuoli  A. Motamed  G. Pasquare  F. Radicati di Brozolo  E. Amin Sobhani 《Bulletin of Volcanology》1976,40(2):121-132

In the Bijar region (Western Iran) two distinct volcanic cycles have been recognized. The first, of Upper Miocene age, consists of high-K cale-alkaline volcanic rocks interpreted as final products of the cale-alkaline Tertiary phase of central Iran. The second volcanic cycle, mostly of Pleistocene age (0.5–1.3 m.v.) consists of undersaturated, mainly potassic, alkaline products. As the lavas of this last phase are slightly fractionated, the chemical differences shown by these rocks have been interpreted as primitive features related to the physical conditions governing the partial melting in the mantle and/or the mantle heterogeneity. In a volcanic center (Sarajukh volcano) contemporaneous basic and acid magmas have been found, and interpreted as derived from two different and independent sources. The alkaline basic volcanism is considered as an expression of disjunctive processes that have affected the western margin of the Iranian plate after the Pliocene.  相似文献   

The geological significance of the manganese-ore mineral facies in the Miocene of the Matese Mountains (Central-Southern Apennines,Italy)     

M. Boni  S. di Nocera 《Mineralium Deposita》1977,12(3):281-292

The geologic significance of the Mn-ore existing in sediments of Serravallian and/or Tortonian age of The Matese Mts. (Central-Southern Appennines) has been reinvestigated, according to more recent criteria. Such deposits originated under the influence of peculiar environments, where the instability of the sedimentary basin, preluding to greater tectonic movements, should have created conditions cyclically euxinic, very similar to those occurring in the strata located between Longano and Pietraroia Formations. Unequal tectonics acting upon Miocene sediments after their deposition, should have caused the secondary remobilisation of Mn-minerals, resulting in irregular patterns of lenses and layers of various thickness.  相似文献