土建專(zhuān)業(yè)畢業(yè)設(shè)計(jì)外文翻譯----地下水

1、<p><b>　　外文資料</b></p><p>　　The Ground-water</p><p>　　The ources of water which supply water front below the earth's surface are called sub-surface sources or ground-water

2、source.Groundwater storage is considerably in excess of all artificial and nature surface storage in the United States.Groundwater distribution may be generally categorize into zones of aeration and asterisked. The satur

3、ated zone ia one in which all the voids are filled with water under hydrostatic pressure.The aeration zone in whiche the interstices are filled partly with air an</p><p>　　The water that can be drained from

4、a soil by gravity is known as the specific yielding. It is expressed as the ratio of the volume of water that can be drained by gravity to the gross volume of the soil.Values of specific yield are dependent on soil parti

5、cle size average, shape and distribution of pore, and degree of completion of the soiled. Average values of specific yield for alluvial aquifers range frome 10% to 20%.</p><p>　　An aquifer is a water-bearing

6、 stratum or formation capble of transmitting water in quantities sufficient to permit development.Aquifers may be considered as falling into two categorise,confined and unconfined,depending on whether or not a wate

7、r table or free within an aquifer is change whenever water is recharged to or discharged from an aquifer.For saturated,confined aquifer,pressure changes produce only slight changs in storage volume.In this cases, the wei

8、ght of the overburden is suppos</p><p>　　Any circumstance that alters the pressure imposed on underground water will also cause a variation in the groundwater level.Seasonal factorshare, change in stream and

9、 river stages,evapotranspiration,atmospheric pressure change, windsor, ides, external load,various forms of withdrawal and recharge,and earthquakes all may produce fluctuations in the level of the water table or the piez

10、ometric surface,depending on whether the aquifer is free or confined.It is important that the engineer concerned w</p><p>　　The rate of movement of water through the ground is of an entirely different magnit

11、ude than that through natural or artificial channels or canddits.Typical value range from 5 fr/day to a few feet per year.The collection of groundwater is accomplished primarily through the construction of wells or infil

12、tration galleries.Numerous factors are involved in the numerical estimation of the performance of these collection works.Some cases are amenable to solution through the utilization of relatively si</p><p>　　

13、Groundwater quantity is influenced considerably by the quality of the source.Changes in source waters or degraded quality of source source supplies may seriously impair the quality of the groundwater supply.Municipal and

14、 industrial wastes entering an aquifer are major sources of organic and inorganic pollution.Large-scale organic pollution of groundwater is infrequent,however,since signficant quantities of organic wastes usually cannot

15、be easily introduced underground.The problem is quite differ</p><p>　　The volumes of groundwater replaced annually through natural mechanisms are relatively small because of the slow rates of movement of gro

16、undwaters and the limited opportunity for surface waters to penetrate the earth's surface.To supplement this natural recharge process,a recent toward artificial recharge has been developing.</p><p>　　In

17、California,for example,artificial recharge is presently a primary method of water conservation.Numerous methods are employed in artificial recharge operation.One of the most common plans is the utilization of holding bas

18、is.The usual practice is to impound the water in a series of reservoir arranged so that the overflow of one will enter the next,and so on.These artificial storage works are generally formed by the construction of dikes o

19、r levee.A second method is the modified streambed,which m</p><p>　　Where slopes are relatively flat and uniform,floodiing provides an economical means of recharge.Normal practice is to spead the recharge wat

20、er over the ground at relatively small depths so as not to disturb the soil or native vegetation.An additional method is the use of injection wells.Recharge rates are normally less than pimping rates for the same head co

21、ndition,however,because of the clogging that is often encountered in the area adjacent to the well casing.Clogging may result from the entra</p><p><b>　　地下水</b></p><p>　　從地表下面提供水的水源叫

22、做地下水。在美國(guó)地下水的儲(chǔ)量相當(dāng)大，以至于超過(guò)了所有人工地上水與自然地上睡的儲(chǔ)量，一般來(lái)說(shuō)，地下水的分布可分為通氣層和水飽和層兩類(lèi)。在水飽和層，由于吸濕作用，所有的孔隙杯水充滿(mǎn)者。而在通氣層中，孔隙中充滿(mǎn)著部分空氣和部分水。通氣層可細(xì)分為三層。（1）濕土層。他從地表開(kāi)始往下延伸到主干層。濕土層的總深度是不斷變化的并取決于土壤類(lèi)型及其植被。在濕土層除了重滲透外，是不能達(dá)到飽和的。在這一層，水可以分為以下三類(lèi)：從空氣中吸收而來(lái)的濕水；由表面

23、張力保持的毛細(xì)管水。還有從土壤中吸取的大量的重力水。（2）中間層從濕土層底部一直延伸到毛細(xì)管作用層的頂部。并且從不存在到幾百英尺的厚度不斷變化。中間層是近地面地區(qū)和近地下水位區(qū)的一個(gè)重要連接環(huán)。滲透水就是從這一環(huán)節(jié)通過(guò)。（3）毛細(xì)管作用層從地下水位延伸到一定的厚度，這一厚度取決于從土壤中吸收毛細(xì)管的高低。毛細(xì)管作用層的厚度隨土質(zhì)的變化而變化，不僅因地域不同而變化還可能在同一地方其厚度也會(huì)不同。</p><p>　

24、　由于重力作用，從土壤中吸收的水叫給水度。給水度可以表示為由重力汲取水量與土壤總量之比。給水度的值取決于土壤顆粒的大小，形狀孔隙分布的密度及土壤的壓實(shí)程度。含水層的給水度的平均值在10%到20%之間。</p><p>　　含水層是一個(gè)能保持水的巖層或者說(shuō)是一個(gè)能夠傳輸足量的水以供水的流動(dòng)和循環(huán)的形成層。含水層可以被看做兩種：受限制的和不受限制的。這取決于在大氣壓下地下水或者自由水面是否存在。</p>

25、<p>　　在含水層，水可能得到補(bǔ)給或者從含水層排出。每當(dāng)這時(shí)含水層的儲(chǔ)水量的細(xì)微變化。在這種情況下，覆蓋層的重量部分是由流體靜壓力支撐，部分是由含水層的固體物質(zhì)支撐。受限的含水層中的流體靜壓力由于用泵抽水或其他方法而降低，那么含水層的負(fù)荷就會(huì)增加。造成了含水層的壓縮。導(dǎo)致一些水從受限含水層中排出。降低流體靜壓力還會(huì)造成受限含水層微小的膨脹。其結(jié)果是導(dǎo)致另一些水分的流失。對(duì)于受限含水層來(lái)說(shuō)，給誰(shuí)的容積度是由儲(chǔ)水系數(shù)來(lái)表示的。

26、這個(gè)存儲(chǔ)系數(shù)可以被定義為含水層所存儲(chǔ)的水的容積或含水層每單位表面積、垂直于地面的水頭的每單位變化釋放的水量。</p><p>　　除了能夠提供讓人滿(mǎn)意的給水度率的持水巖層外，還有不持水巖層和不透水巖層。隔水層就是一種不透水巖層，可以容納大量的水，但是他沒(méi)有足夠的導(dǎo)水速率以使的水得到高效發(fā)展和利用。無(wú)水層是一種不透水并且不含水的底層。</p><p>　　在任何情況下，只要改變壓在地下水上的

27、壓力，就會(huì)導(dǎo)致地下水位的變化。季節(jié)因素，江河水位變化，蒸發(fā)，大氣壓變化，風(fēng)力，潮汐，外部壓力，抽水及補(bǔ)水的各種形式以及地震，所有這些都可以引起地下水位的變化或測(cè)壓水面的變化。這取決于巖層的自由還是受限的。對(duì)于一個(gè)從事有關(guān)地下水供給的發(fā)展和利用工程師說(shuō)，時(shí)刻注意這些因素非常重要，工程師還應(yīng)該能夠判斷庫(kù)操作的重要關(guān)系。上訴因素與具體地下水。</p><p>　　水在地下流動(dòng)的速率與水在自然或人工制成餓水渠和水管中流動(dòng)

28、的速率具有完全不同的重要性。具體的速率值從每天5英尺到每年幾英寸不等。地下水的收集最初是通過(guò)修建水井和滲透坑來(lái)完成的。在這些收集工作能力的數(shù)字評(píng)估涉及到很多因素，有些適用于用相對(duì)簡(jiǎn)單的數(shù)學(xué)表達(dá)式來(lái)解決的。系統(tǒng)考慮起來(lái)，可能要有三部分組成。井的結(jié)構(gòu)，抽水機(jī)和排水管道系統(tǒng)。就井自身而言，它就包含一個(gè)敞開(kāi)的部分進(jìn)入井內(nèi)并且通過(guò)管被輸送到地表，敞開(kāi)的部分通常是一個(gè)表面有許多小孔餓管或者是開(kāi)有溝槽餓鐵板，這塊鐵板允許水流進(jìn)入的同時(shí)也阻止了小孔的破

29、損。有時(shí)候一些沙礫在井管的底部堆積沒(méi)把鐵板圍住。當(dāng)從井中抽水，水就立刻從鐵板附近的含水層中流出。然后水流就在離井有一段距離的地方變得固定起來(lái)，以確保對(duì)這次抽水的補(bǔ)給。由于土壤對(duì)水流的阻力，抽水會(huì)有很多損失并且附近抽水井的量壓面就會(huì)凹陷。這被稱(chēng)作降混漏斗。降混漏斗會(huì)一直擴(kuò)大直到均衡的狀況達(dá)到穩(wěn)定餓環(huán)境確定為止。</p><p>　　地下水的質(zhì)量受源地的影響特別大。水源的變化或是源地供水的降級(jí)質(zhì)量都可能?chē)?yán)重地?fù)p害地下

30、供水的質(zhì)量。進(jìn)入含水層的城市和工業(yè)廢棄物是有機(jī)污染和無(wú)機(jī)污染餓主要來(lái)源。然而，由于大量的有機(jī)廢物通常不易進(jìn)入到地下，所以大規(guī)模的地下水有機(jī)污染不會(huì)經(jīng)常發(fā)生。而有關(guān)無(wú)機(jī)污染的問(wèn)題就不同了，這是因?yàn)闊o(wú)機(jī)污染會(huì)很容易穿梭于土壤并且一旦進(jìn)入土壤就會(huì)費(fèi)很大勁才能被清除。另外，這種無(wú)機(jī)污染的不良影響會(huì)無(wú)限期地進(jìn)行，因?yàn)橄♂尫浅Ｂ?，并且人工沖洗或處理往往是行不通或者是造價(jià)太高。當(dāng)水流從土壤中流過(guò)，溶解鹽的數(shù)量會(huì)大大增加，降水和水流會(huì)造成土壤餓風(fēng)蝕和侵

31、蝕，然后形成可溶物，這些溶解鹽被這些可容物吸收。從大水漫灌的下游地區(qū)可以發(fā)現(xiàn)，澆灌的水太咸，而達(dá)不到令人滿(mǎn)意餓莊稼收成。這些含鹽的污染物很難控制，因?yàn)轵?qū)除方法過(guò)于昂貴。一個(gè)可能解決辦法就是用含鹽污染物較低的水來(lái)稀釋?zhuān)ɡ?，廢水處理工廠(chǎng)的污水）。這樣通過(guò)混合產(chǎn)出的平均鹽度的水適合于灌溉。消除廢棄物，保護(hù)地下水儲(chǔ)量免于不可治愈的傷害，還需要大量的努力。</p><p>　　由于地下水流動(dòng)速度相當(dāng)緩慢以及極少有地表水入

32、滲到地球內(nèi)部，每年地下水中只有一部分才得以通過(guò)自然物理過(guò)程得以替換。為了彌補(bǔ)這種自然回灌過(guò)程的不足，近年興起一種人工回灌的新潮流。</p><p>　　例如，在加利福尼亞，人工回灌是現(xiàn)在蓄水餓一種主要方式。人們?cè)谌斯せ毓嗖僮鲿r(shí)采用很多方法，其中最常見(jiàn)的方法之一就是使用蓄水池蓄水。通常的做法是把水?dāng)r截到一連串事先已建好的蓄水池中，因此水從一個(gè)蓄水池里流出來(lái)將會(huì)進(jìn)入下一個(gè)蓄水池，以此類(lèi)推。這些人工蓄水工程通常得挖建溝

33、壕或者筑堤。另一種方式是改良河床，這種方式運(yùn)用的是自然水供給。人們將河床拓寬，整平毀掉，或者是采用一系列方法去增加它的蓄水量。溝和槽在這里是被應(yīng)用：溝梁布設(shè)的基本類(lèi)型有等高線(xiàn)型，即溝梁沿地表面等高線(xiàn)布設(shè)；側(cè)向型，即把水從側(cè)向進(jìn)入,引入許多小溝梁中：樹(shù)枝狀貨分支型，即把水從生河道引入連接在一起餓較小渠和溝中。</p><p>　　當(dāng)坡度相對(duì)平緩和一致是，洪水就是一種經(jīng)濟(jì)的回灌方式。通常的做法是將相對(duì)較少的回灌水撒于