-土木工程專(zhuān)業(yè)畢業(yè)設(shè)計(jì)外文翻譯---地下空間的利用-建筑結(jié)構(gòu)

1、地下空間的利用全球城市化進(jìn)程的加快將會(huì)對(duì)人類(lèi)將來(lái)的生存方式產(chǎn)生重大影響。隨著全球人口的增長(zhǎng)以及更多國(guó)家要求提高生活水平，世界必須提供更多食物，能源以及礦物資源來(lái)維持此增長(zhǎng)趨勢(shì)。解決這一難題的辦法有三大渠道復(fù)合而成：農(nóng)業(yè)用地的保護(hù)從而得到更深入的利用；日益增長(zhǎng)的全球城市人口；對(duì)保護(hù)和改善環(huán)境日益增長(zhǎng)的關(guān)注，特別是關(guān)于全球氣候變暖以及人口增長(zhǎng)帶來(lái)的影響。地下空間的利用，作為本章要描述的內(nèi)容，將提供針對(duì)這些趨勢(shì)的解決辦法。通過(guò)將特殊器材設(shè)備置于地下，城市地表可被更有效地利用，這樣就可釋放出空間供農(nóng)業(yè)和娛樂(lè)使用。類(lèi)似的，在陡峭的山坡上使用階地掩土住宅會(huì)有助于在多山地區(qū)保護(hù)寶貴的可耕平地。利用地下空間也

2、可以提高人們?cè)谌丝诟呙芗サ木幼∈孢m度，改善生活質(zhì)量。一城市或當(dāng)?shù)厮疁?zhǔn)，地下設(shè)施的利用正日益滿(mǎn)足當(dāng)今社會(huì)對(duì)于改善環(huán)境的需求。例如不論城市還是農(nóng)村都需要提高運(yùn)輸，實(shí)用以及娛樂(lè)服務(wù)。世界上許多城市的交通堵塞問(wèn)題已經(jīng)處在滿(mǎn)足人類(lèi)基本生存需求的臨界點(diǎn)上，并且在不破壞地表環(huán)境的基礎(chǔ)上不增加新設(shè)施或是不重新規(guī)劃現(xiàn)有土地及周邊地帶上的建筑的基礎(chǔ)上想要解決這一難題是十分困難的。以世界上許多國(guó)家的國(guó)家水平，全球化的趨勢(shì)導(dǎo)致對(duì)煤炭，石油，天然氣的開(kāi)采已達(dá)到更深的地層以下，觸及更難以讓人接受或是更敏感的區(qū)域。這些趨勢(shì)同樣導(dǎo)致針對(duì)能源繁衍存貯系統(tǒng)以及用于處理危險(xiǎn)廢料（包括化學(xué)，生物以及放射性廢料）的國(guó)家設(shè)施設(shè)計(jì)的改善

3、和提高，同樣也改善了國(guó)家高速運(yùn)輸體系。所有這些發(fā)展均涉及地下工程。用地壓力將設(shè)施置于地下是緩解由于世界人口增長(zhǎng)所帶來(lái)的城市化問(wèn)題的一種有希望的辦法。雖然世界平均人口密度并不大，但人口分布卻極不均勻。世界人口密度圖顯示世界上大部分地方根本不適合居住。這些大方大部分是沙漠山區(qū)，或是極度嚴(yán)寒地帶等人類(lèi)不易居住區(qū)。以中國(guó)為例，平均人口密度大概是每平方公里100人，但是10億多的絕大部分人口居住在少于20%的國(guó)土上。這是那些可以提供糧食產(chǎn)品的肥沃土地。然而，由于人口增長(zhǎng)和城市化，這些土地同樣要被用于創(chuàng)建更廣闊的運(yùn)輸系統(tǒng)，被用于工商業(yè)的發(fā)展，以及日益增長(zhǎng)的住房需求。隨著人口和經(jīng)濟(jì)的增長(zhǎng)，農(nóng)業(yè)用地減少，向城

4、市人口運(yùn)送食物和原材料的問(wèn)題日益增長(zhǎng)。據(jù)估計(jì)，到2000年，世界人口的70%將居住在城市。同樣的問(wèn)題在日本也很明顯，大約80%的土地是山區(qū)，90%的人口居住在海邊平原經(jīng)濟(jì)發(fā)展集中在幾個(gè)相關(guān)的經(jīng)濟(jì)中心。平原通常是最肥沃的土地，從歷史上看也是人類(lèi)的定居地。其他附加于人口密度的因素包括：傳統(tǒng)低層的建筑模式，而且日本法律規(guī)定必須建造靠近陽(yáng)光的堅(jiān)固的維護(hù)設(shè)施。同樣，為了保護(hù)家庭糧食生產(chǎn)能力，日本政府保護(hù)農(nóng)業(yè)用地。這些歷史，政策因素導(dǎo)致大量商業(yè)，個(gè)人向經(jīng)濟(jì)中心移民造成了巨大的土地使用壓力。結(jié)果是市中心土地價(jià)格驚人昂貴（高達(dá)50萬(wàn)美圓/平米）并且很難為人們提供住房，交通，設(shè)施服務(wù)。普通公司雇員無(wú)法承擔(dān)住在他

5、們工作的市中心附近而不得不搭乘公汽單程花1.2個(gè)小時(shí)從他們負(fù)擔(dān)的起的住處到公司。為了為日益擴(kuò)大的大城市區(qū)域提供服務(wù)，市政當(dāng)局必須升級(jí)道路并且興建新的交通線和設(shè)施。東京市中心的土地價(jià)格如此昂貴以至于用于購(gòu)買(mǎi)土地的花費(fèi)可能會(huì)占到工程總花費(fèi)的95%。土地使用壓力和由于高土地使用價(jià)格帶來(lái)的相關(guān)經(jīng)濟(jì)影響使得對(duì)地下空間的潛在利用的研究變得相當(dāng)有趣。當(dāng)?shù)乇硗恋匾驯焕么M，地下空間將變成可開(kāi)發(fā)的區(qū)域之一。這為不需深度破壞地表環(huán)境而附加需要設(shè)備提供了一種可能。雖然沒(méi)有高額地價(jià)，但是建造地下設(shè)施的高額花費(fèi)將是地下空間利用的一大攔路虎。因?yàn)榈叵略O(shè)施不具有經(jīng)濟(jì)競(jìng)爭(zhēng)力，因此在考慮建造前必須在美學(xué)，環(huán)境或者是社會(huì)效應(yīng)方

6、面給予綜合評(píng)估，除非是一些有特殊標(biāo)志性意義的設(shè)施否則將會(huì)造成現(xiàn)階段國(guó)家無(wú)法承擔(dān)或是很勉強(qiáng)承擔(dān)的奢侈浪費(fèi)。地下空間規(guī)劃對(duì)地下空間利用的有效規(guī)劃是發(fā)展地下設(shè)施的前奏。這個(gè)計(jì)劃必須是為長(zhǎng)遠(yuǎn)考慮的，并根據(jù)人們理想的工作和居住環(huán)境重構(gòu)城市建筑格局。如果地下空間開(kāi)發(fā)可以提供最具價(jià)值的長(zhǎng)期效益，那么對(duì)這些資源的有效計(jì)劃就應(yīng)得以實(shí)施。不幸的是，在世界范圍內(nèi)，靠公眾權(quán)力來(lái)開(kāi)發(fā)近地表空間已經(jīng)太遲了。紊亂的設(shè)施網(wǎng)絡(luò)司空見(jiàn)慣歸咎于缺乏協(xié)調(diào)以及使用設(shè)施的歷史性變革以及交通系統(tǒng)的發(fā)展。地下空間具有如此特征導(dǎo)致要做一個(gè)好的規(guī)則需要特別注意一些問(wèn)題1.一旦開(kāi)始地下開(kāi)挖，土地將被永久改變。地下建筑不象表面建筑那樣容易拆掉。2.

7、開(kāi)挖一片地下空間需要一大片土地作為開(kāi)挖加固區(qū)。3.土地的地理構(gòu)成極大地影響了地下設(shè)施的種類(lèi)，形式以及開(kāi)銷(xiāo)。但現(xiàn)有關(guān)于地表建筑的知識(shí)僅有很有限的內(nèi)容與此相關(guān)，因此需要查閱鉆探資料和以前的記錄。4.大型地下工程需要大量調(diào)查，涉及更大的建造問(wèn)題，工期拖延以及預(yù)算超支等風(fēng)險(xiǎn)。5.傳統(tǒng)規(guī)則技術(shù)主要側(cè)重于對(duì)于城市地形區(qū)域的二維描述。這基本上僅適合地表及上部結(jié)構(gòu)但并不適合建造在處于復(fù)雜三維地理環(huán)境中的地下結(jié)構(gòu)。用同一種模式來(lái)描述這種三維信息并立刻反映到規(guī)則評(píng)估中是件非常困難的事例如，在東京，第一條地鐵（Ginza線）是在現(xiàn)存地表層設(shè)施下作為一個(gè)影子工程線路（10m深）建成的。隨著填加更多的地鐵線，在更深土層

8、中才會(huì)發(fā)現(xiàn)比較規(guī)整的區(qū)域。在東京，新的KeiyoJR線深達(dá)40m。一條從Marunouchi到Shinjuku的高速干線已被設(shè)計(jì)到50m深。作為比較在倫敦最深的設(shè)施大約70m深，其主要復(fù)雜部分以及排水設(shè)施至少超過(guò)25m綜合日益增長(zhǎng)的需要，有一個(gè)事實(shí)就是這類(lèi)新型運(yùn)輸服務(wù)（例如日本的新干線子彈頭列車(chē)或是法國(guó)的TGV）通常需要大量交叉隧道，筆直的隊(duì)列以及平坦性。如果地下空間不是此類(lèi)用途，那么城市下面將會(huì)產(chǎn)生非常無(wú)效率的布局。環(huán)境利益另一個(gè)利用地下空間的主要策略是全球日益增長(zhǎng)的對(duì)環(huán)境問(wèn)題的關(guān)注，并導(dǎo)致人們重新考慮城市的將來(lái)和工業(yè)的發(fā)展。在關(guān)注維持生態(tài)平衡和環(huán)境惡化以及全球有限的自然資源要考慮以下幾個(gè)問(wèn)

9、題：在提高經(jīng)濟(jì)增長(zhǎng)保持工業(yè)模式的同時(shí)保護(hù)環(huán)境，延長(zhǎng)地球上資源的壽命即使不是一個(gè)不可能的問(wèn)題也是一個(gè)很復(fù)雜的問(wèn)題。無(wú)論如何，高生活標(biāo)準(zhǔn)和高國(guó)內(nèi)生產(chǎn)總值（GDP）不需要和資源的消耗和環(huán)境的惡化程度成比例。地下空間的利用能從幾種途徑解決環(huán)境/資源的窘境。地下設(shè)施以其自身特點(diǎn)成為一種典型的儲(chǔ)能設(shè)施。更重要的是，通過(guò)地下空間的利用，城市人口密度會(huì)提高但對(duì)環(huán)境的影響會(huì)減少。相對(duì)于保護(hù)綠地及耕地等的明顯好處，附加于此的好處是-有充分證據(jù)顯示高城市密度可以減少礦物燃料的消耗。將來(lái)地下空間的發(fā)展雖然在全世界范圍內(nèi)現(xiàn)有的地下設(shè)施為將來(lái)地下空間的發(fā)展提供了一些范例，但他們都在尺寸上，用途上或者對(duì)于城市整體環(huán)境缺乏考

10、慮。作為更佳細(xì)致規(guī)劃和研究的補(bǔ)充，未來(lái)的規(guī)劃者和設(shè)計(jì)者已提出對(duì)大范圍地下結(jié)構(gòu)甚至從整個(gè)城市的角度綜合考核，將是非常有用的。90年代地理一個(gè)1990年4月在日本舉行的研討博覽會(huì)，主要是一個(gè)關(guān)于日本地下工業(yè)情況的論壇。一大堆關(guān)于地下的概念展示出來(lái)從典型的運(yùn)輸使用設(shè)施到展望中的用于災(zāi)難時(shí)刻保護(hù)通訊網(wǎng)絡(luò)的地下走廊。這類(lèi)走廊對(duì)于在城市地鐵站和中心生產(chǎn)去附近以及市區(qū)外安置地點(diǎn)間運(yùn)送廢棄物和能源也十分有效。這一點(diǎn)不僅緩解了堵塞而且提供了更加有效的能源衍生和廢物循環(huán)。這些概念都是針對(duì)城市建筑的升級(jí)，將最終導(dǎo)致地表形成更開(kāi)闊的空間以及更高效更吸引人的全局環(huán)境。當(dāng)展望將來(lái)城市建設(shè)時(shí)，地下建筑會(huì)成為主要因素這是建筑

11、師Paolo Soleri在過(guò)去30年的幻想杰作。在科幻小說(shuō)里，未來(lái)城市常被描繪成自我供養(yǎng)的，氣候可控制的單位，且常常位于地下以避免來(lái)自危險(xiǎn)或環(huán)境污染等因素的侵襲。在這種情況下，地球上的地下城市略不同于以月球或其他孤立環(huán)境為基礎(chǔ)創(chuàng)建的城市。高層建筑前 沿高層建筑的定義很難確定?？梢哉f(shuō)2-3層的建筑物為底層建筑，而從3-4層地10層或20層的建筑物為中層建筑，高層建筑至少為10層或者更多。盡管在原理上，高層建筑的豎向和水平構(gòu)件的設(shè)計(jì)同低層及多層建筑的設(shè)計(jì)沒(méi)什么區(qū)別，但使豎向構(gòu)件的設(shè)計(jì)成為高層設(shè)計(jì)有兩個(gè)控制性的因素：首先，高層建筑需要較大的柱體、墻體和井筒；更重要的是側(cè)向里所產(chǎn)生的傾覆力矩和剪力變

12、形要大的多，必要謹(jǐn)慎設(shè)計(jì)來(lái)保證。高層建筑的豎向構(gòu)件從上到下逐層對(duì)累積的重力和荷載進(jìn)行傳遞，這就要有較大尺寸的墻體或者柱體來(lái)進(jìn)行承載。同時(shí)，這些構(gòu)件還要將風(fēng)荷載及地震荷載等側(cè)向荷載傳給基礎(chǔ)。但是，側(cè)向荷載的分布不同于豎向荷載，它們是非線性的，并且沿著建筑物高度的增加而迅速地增加。例如，在其他條件都相同時(shí)，風(fēng)荷載在建筑物底部引起的傾覆力矩隨建筑物高度近似地成平方規(guī)律變化，而在頂部的側(cè)向位移與其高度的四次方成正比。地震荷載的效應(yīng)更為明顯。對(duì)于低層和多層建筑物設(shè)計(jì)只需考慮恒荷載和部分動(dòng)荷載時(shí)，建筑物的柱、墻、樓梯或電梯等就自然能承受大部分水平力。所考慮的問(wèn)題主要是抗剪問(wèn)題。對(duì)于現(xiàn)代的鋼架系統(tǒng)支撐設(shè)計(jì)，

13、如無(wú)特殊承載需要，無(wú)需加大柱和梁的尺寸，而通過(guò)增加板就可以實(shí)現(xiàn)。不幸的是，對(duì)于高層建筑首先要解決的不僅僅是抗剪問(wèn)題，還有抵抗力矩和抵抗變形問(wèn)題。高層建筑中的柱、梁、墻及板等經(jīng)常需要采用特殊的結(jié)構(gòu)布置和特殊的材料，以抵抗相當(dāng)高的側(cè)向荷載以及變形。如前所述，在高層建筑中每平方英尺建筑面積結(jié)構(gòu)材料的用量要高于低層建筑。支撐重力荷載的豎向構(gòu)件，如墻、柱及井筒，在沿建筑物整個(gè)高度方向上都應(yīng)予以加強(qiáng)。用于抵抗側(cè)向荷載的材料要求更多。對(duì)于鋼筋混凝土建筑，雖著建筑物層數(shù)的增加，對(duì)材料的要求也隨著增加。應(yīng)當(dāng)注意的是，因混凝土材料的質(zhì)量增加而帶來(lái)的建筑物自重增加，要比鋼結(jié)構(gòu)增加得多，而為抵抗風(fēng)荷載的能力而增加的材

14、料用量卻不是呢么多，因?yàn)榛炷磷陨淼闹亓靠梢缘挚箖A覆力矩。不過(guò)不利的一面是混凝土建筑自重的增加，將會(huì)加大抗震設(shè)計(jì)的難度。在地震荷載作用下，頂部質(zhì)量的增加將會(huì)使側(cè)向荷載劇增。無(wú)論對(duì)于混凝土結(jié)構(gòu)設(shè)計(jì)，還是對(duì)于鋼結(jié)構(gòu)設(shè)計(jì)，下面這些基本的原則都有助于在不需要增加太多成本的前提下增強(qiáng)建筑物抵抗側(cè)向荷載的能力。1. 增加抗彎構(gòu)件的有效寬度。由于當(dāng)其他條件不變時(shí)能夠直接減小扭矩，并以寬度增量的三次冪形式減小變形，因此這一措施非常有效。但是必須保證加寬后的豎向承重構(gòu)件非常有效地連接。2. 在設(shè)計(jì)構(gòu)件時(shí)，盡可能有效地使其加強(qiáng)相互作用力。例如，可以采用具有有效應(yīng)力狀態(tài)的弦桿和桁架體系；也可在墻的關(guān)鍵位置加置鋼筋；

15、以及最優(yōu)化鋼架的剛度比等措施。3. 增加最有效的抗彎構(gòu)件的截面。例如，增加較低層柱以及連接大梁的翼緣截面，將可直接減少側(cè)向位移和增加抗彎能力，而不會(huì)加大上層樓面的質(zhì)量，否則，地震問(wèn)題將更加嚴(yán)重。4. 通過(guò)設(shè)計(jì)使大部分豎向荷載，直接作用于主要的抗彎構(gòu)件。這樣通過(guò)預(yù)壓主要的抗傾覆構(gòu)件，可以使建筑物在傾覆拉力的作用下保持穩(wěn)定。5. 通過(guò)合理地放置實(shí)心墻體及在豎向構(gòu)件中使用斜撐構(gòu)件，可以有效地抵抗每層的局部剪力。但僅僅通過(guò)豎向構(gòu)件進(jìn)行抗剪是不經(jīng)濟(jì)的，因?yàn)槭怪傲河凶銐虻目箯澞芰Γ扔脡蛐睋涡枰嗖牧虾褪┕すぷ髁俊?. 每層應(yīng)加設(shè)充足的水平隔板。這樣就會(huì)使各種抗力構(gòu)件更好地在一起工作，而不是單獨(dú)工作

16、。7. 在中間轉(zhuǎn)換層通過(guò)大型豎向和水平構(gòu)件及重樓板形成大框架，或者采用深梁體系。應(yīng)當(dāng)注意的是，所有高層建筑的本質(zhì)都是地面支撐的懸臂結(jié)構(gòu)。如何合理地運(yùn)用上面所提到的原則，就可以利用合理地布置墻體、核心筒、框架、筒式結(jié)構(gòu)和其他豎向結(jié)構(gòu)分體系，使建筑物取得足夠的水平承載力和剛度。本文后面將對(duì)這些原理的應(yīng)用做介紹。剪力墻結(jié)構(gòu)在能夠滿(mǎn)足其他功能需求時(shí)，高層建筑中采用剪力墻可以經(jīng)濟(jì)地進(jìn)行高層建筑的抗側(cè)向荷載設(shè)計(jì)。例如，住宅樓需要很多隔墻，如果這些隔墻都設(shè)計(jì)為實(shí)例的，那么他們可以起到剪力墻的作用，既能抵抗側(cè)向荷載，又能承受豎向荷載。對(duì)于20層以上的建筑物，剪力墻極為常見(jiàn)。如果給與足夠的寬度，剪力墻能夠有效地

17、抵抗30-40層甚至更多的側(cè)向荷載。但是，剪力墻只能抵抗平行于墻平面的荷載（也就是說(shuō)不能抵抗垂直于墻的荷載）。因此有必要經(jīng)常在兩個(gè)相互垂直的方向設(shè)置剪力墻，或者在盡可能多的方向布置，以用來(lái)抵抗各個(gè)方向的側(cè)向荷載。并且，墻體設(shè)計(jì)還應(yīng)考慮扭轉(zhuǎn)的問(wèn)題。在設(shè)計(jì)過(guò)程中，兩片或者更多的剪力墻會(huì)布置成L型或者槽形。實(shí)際上，四片內(nèi)剪力墻可以被聯(lián)結(jié)成矩形，以更有效地抵抗側(cè)向荷載。如果所有外部剪力墻都連接起來(lái)，整個(gè)建筑物就像是一個(gè)筒體，將會(huì)具有很強(qiáng)的抵抗水平荷載和抵抗扭矩的能力。通常混凝土就剪力墻都是實(shí)體的，并在有要求時(shí)開(kāi)洞，而鋼筋剪力墻常常是做成桁架式。這些桁架上可能布置成蛋單斜撐、X斜撐及K斜撐。在側(cè)向力作用

18、下這些桁架的組合構(gòu)件受到或拉或壓力。從強(qiáng)度和變形控制角度來(lái)說(shuō)，桁架有著很好的功效，并且管道可以在構(gòu)件之間穿過(guò)。當(dāng)然，鋼桁架墻的斜向構(gòu)件在墻體上要正確放置，以免妨礙開(kāi)窗、循環(huán)以及管道穿墻。如上所述，電梯強(qiáng)、樓梯間及設(shè)備豎井都可以形成筒狀體，常常用它們既抵抗豎向荷載又抵抗水平荷載。這些筒的橫斷面一般駛矩形或圓形，由于筒結(jié)構(gòu)作用，筒狀結(jié)構(gòu)能夠有效地進(jìn)行各個(gè)方向上的抗彎和抗剪。不過(guò)在這樣的結(jié)構(gòu)設(shè)計(jì)中存在的問(wèn)題是，如何保證在門(mén)洞口和其他孔洞的強(qiáng)度。對(duì)于鋼筋混凝土結(jié)構(gòu)，通過(guò)使用特殊的鋼筋配置在這些孔洞的周?chē)?duì)于鋼剪力墻，則要求在開(kāi)洞處加強(qiáng)節(jié)點(diǎn)連接，以抵抗洞口變形。對(duì)于很多高層建筑，如果墻體和筒架進(jìn)行合理

19、地安排與連接，會(huì)起到很好的抵抗側(cè)向荷載的作用。還要求由這些結(jié)構(gòu)分體系提供的剛度在各個(gè)方向上應(yīng)大體對(duì)稱(chēng)?？蚣芙Y(jié)構(gòu)在建筑物結(jié)構(gòu)設(shè)計(jì)中，用于抵抗豎向和水平荷載的框架結(jié)構(gòu)，常作為一個(gè)重要且標(biāo)準(zhǔn)的型式而被采用。它適用于低層、多層建筑物，亦可用于70-100層高的高層建筑物。同剪力墻結(jié)構(gòu)相比，這種結(jié)構(gòu)更適合在建筑物的內(nèi)部或者外圍的墻體上開(kāi)設(shè)矩形孔洞。同時(shí)它還能充分利用建筑物內(nèi)在任何情況下都要采用的梁和柱的剛度，但當(dāng)柱子與梁剛性連接時(shí)，通過(guò)框架受彎來(lái)抵抗水平和豎向荷載會(huì)使這些柱子的承載能力變得更大。大多情況下，框架的剛度不如剪力墻，因此對(duì)于細(xì)長(zhǎng)的建筑物將會(huì)出現(xiàn)過(guò)度變形。但正是因?yàn)槠淙嵝裕沟闷渑c剪力墻結(jié)構(gòu)相

20、比具有更大的延性，因而地震荷載下不易發(fā)生事故。例如，如果框架局部出現(xiàn)超應(yīng)力時(shí)，那么其延性就會(huì)允許整個(gè)結(jié)構(gòu)出現(xiàn)倒塌事故。因此，框架結(jié)構(gòu)常被視為最好的高層抗震結(jié)構(gòu)。另一方面，設(shè)計(jì)得好的剪力墻結(jié)構(gòu)也不可能倒塌。對(duì)于混凝土框架結(jié)構(gòu)，還存在較大的分歧。的確。如果在混凝土框架設(shè)計(jì)時(shí)不進(jìn)行特殊的延性設(shè)計(jì)，那么他將很難承受比設(shè)計(jì)標(biāo)準(zhǔn)值大很多倍的地震荷載的沖擊。因此，很多人認(rèn)為它不具備鋼框架所具備的超載能力。不過(guò)最新的研究i和實(shí)驗(yàn)表明，當(dāng)混凝土中放入充分的鋼箍和節(jié)點(diǎn)鋼筋時(shí) ，混凝土框架框架也能表現(xiàn)出很好的延性。新建筑規(guī)范對(duì)所謂延性混凝土框架有專(zhuān)門(mén)的規(guī)定。然而，這些規(guī)范往往要求在框架的某處增設(shè)過(guò)多的鋼筋，這就增加

21、了施工的難度。盡管這樣，混凝土框架設(shè)計(jì)還是具備既經(jīng)濟(jì)又實(shí)用的特性。當(dāng)然，還可以在建筑結(jié)構(gòu)設(shè)計(jì)中，將框架結(jié)構(gòu)和剪力墻結(jié)構(gòu)結(jié)合起來(lái)使用。例如，在房屋建筑上使用框架，而在另一方向上可以使用剪力墻。結(jié)論以上所述就是高層建筑最普通的結(jié)構(gòu)形式。在設(shè)計(jì)過(guò)程中，應(yīng)盡可能經(jīng)濟(jì)實(shí)用地選擇合理的形式。Underground Space UtilizationThe rapid growth of world civilization will have a significant impact on the way humans live in the future. As the global populatio

22、n increases and more countries demand a higher standard of living, the difficulty of doing this is compounded by three broad trends: the conversion of agricultural land to development uses; the increasing urbanization of the worlds population; and growing concern for the maintenance and improvement

23、of the environment, especially regarding global warming and the impact of population growth. Underground space utilization, as this chapter describes, offers opportunities for helping address these trends.By moving certain facilities and function underground, surface land in urban areas can be used

24、more effectively , thus freeing space for agricultural and recreational purpose. Similarly, the use of terraced earth sheltered housing. Using underground space also enables humans to live more comfortably in densely populated areas while improving the quality of live.On an urban or local level, the

25、 use of underground facilities is rising to accommodate the complex demands of todays society while improving the environment . For example, both urban and rural areas are requiring improved transportation, utility, and recreational services. The state of traffic congestion in many urban areas of th

26、e world is at a critical level for the support of basic human living, and it is difficult if not impossible to add new infrastructure at ground level without causing an unacceptable deterioration of the surface environment or an unacceptable relocation of existing land uses and neighborhoods.On a na

27、tional level in countries around the world, global trends are causing the creation and extension of mining developments and oil or gas recovery at greater depths and in more inaccessible or sensitive locations. Three trends have also led to the developments of improved designs for energy generation

28、and storage systems as well as national facilities for dealing with hazardous waste (including chemical, biological, and radioactive waste ), and improved high-speed national transportation systems .All these developments involve use of the underground .Land Use Pressures Placing facilities undergro

29、und is a promising method for helping ease land use pressures caused by the growth and urbanization of the worlds population. Although the average population density in the world is not large, the distribution of population is very uneven. A map of population density in the world is not large ,areas

30、 of the world are essentially uninhabited . These areas are for the most part deserts ,mountainous regions, or regions of severe cold that do not easily support human habitation.If one examines China ,for example ,the average population density is approximately 100 persons per square kilometer, but

31、the vat majority of the one billion-plus population lives on less than 20 percent of the land area. this is the fertile land that can support food production. However, due to population growth, urbanization, and economic growth, this same land must now support extensive transportation systems, indus

32、trial and commercial development, and increasing demands for housing, As the population and economy grow, the land available for agriculture shrinks, and the problems of transporting food and raw materials to an urban population increase. By the year 2000 it is estimated that 70 percent of the world

33、s population will inhabit urban areas.The same trend are evident in Japan, where approximately 80 percent of the land area is mountainous,90 percent of the population lives on the coastal plains, and economic development is concentrated in relatively few economic development is concentrated in relat

34、ively few economic centers .The flat-lying land is generally the most fertile and is historically the region of settlement . Other factors adding to population density include the traditional building style , which is low-rise , and Japanese law that contain strong provisions for maintenance of acce

35、ss to sunlight .Also ,to retain domestic food production capability , the Japanese government has protected agricultural land from development. The combination of these historical and political factors together with a strong migration of businesses and individuals to the economic centers has created

36、 enormous land use pressure. The result is an astronomically high cost of land in city centers (as high as US $500,00 per square meter) and difficulty in an providing housing, transportation, and utility services for the population. Typical business employees cannot afford to live near the city cent

37、er where they work and may have to commute one to two hours each way from an affordable area. To service the expanding metropolitan area, public agencies must upgrade roads and build new transit lines and utilizes. Land costs for such work are so high that in central Tokyo, the cost of land may repr

38、esent over 95 percent of the total cost of a project.The problem of land use pressures and related economic effects of high land prices are of great interest in the study of the potential uses of underground space. When surface space is fully utilized, underground space becomes one of the few develo

39、pment zones available. It offers the possibility of the adding needed facilities without further degrading the surface environment. Without high land prices, however, the generally higher cost of constructing facilities underground is a significant deterrent to their environmental, or social grounds

40、-luxuries which many developing nation cannot afford at present and which developed nations are reluctant to undertake except in areas of special significance. Planning of Underground Space Effective planning for underground utilization should be an essential precursor to the development of major un

41、derground facilities. This planning must consider long-term needs while providing a frame work for reforming urban areas into desirable and effective environments in which to live and work. If underground development is to provide the most valuable long-term benefit possible , then effective zones b

42、eneath public rights-of-way in older cities around the world. The tangled wed of utilizes commonly found is due to a lack of coordination and the historical evolution in utility provision and transit system development. The underground has several characteristics that make good planning especially p

43、roblematical:l Once underground excavations are made, the ground is permanently altered. Underground structures are not as easily dismantled as surface buildings.l An underground excavation may effectively a large zone of the stability of the excavation.l The underground geologic structure greatly a

44、ffects the type, size, and costs of facilities that can be constructed, but the knowledge of a regions can only be inferred from a limited number of site investigation borings and previous records.l Large underground projects may require massive investments with relatively high risks of construction

45、 problem, delay, and cost overruns.l Traditional planning techniques have focused on two-dimensional representations of regions and urban areas . This is generally adequate for surface and aboveground construction but it is not adequate for the complex three-dimensional geology and built structures

46、often found underground . Representation of this three-dimensional information in a form that can readily be interpreted for planning and evaluation is very difficult.In Tokyo, for example, the first subway line (Ginza Line) was installed as a shallow line (10 meters deep) immediately beneath the ex

47、isting layer of surface utilities. As more subway lines have been added, uncluttered zones can only be found at the deeper underground levels. The new Keiyo JR line in Tokyo is 40 meter deep. A new underground super highway from Marunouchi to Shinjuku has been proposed at a 50-meter depth. For compa

48、rison, the deepest installations in London are at approximately a 70-meter depth although the main complex of works and sewers is at less than 25 neters. Compounding these issues of increasing demand is the fact newer transportation services (such as the Japanese Shinkansen bullet trains or the Fren

49、ch TGV) ofen require larger cross-section tunnels, straighter alignments, and flatter grades. If space is not reserved for this type of use, very inefficient layouts of the beneath urban areas can occur.Environmental Benefits Another major trigger for under ground space usage is the growing internat

50、ional concern over the environment, which has led to attempts to rethink the future of urban and industrial development. The major concerns in balancing economic development versus environmental degradation and world natural resource limitations revolve around several key issues. These are:l The inc

51、reasing consumption of energy compared to the limited reserves of fossil fuels available to meet future demand.l The effect on the global climate of burning fossil fuels.l The pollution of the environment from the by-products of industrial developmentl The safe disposal of hazardous wastes generated

52、 by industrial and military activites.Preserving the environment from the by-products of industrial development economic growth and maintaining individual life styles will be complex if not impossible. However, a high standard of living and high gross domestic product do not have to be proportionate

53、ly dependent on resource consumption and environmental degradation.Underground space utilization can help solve the environmental/resource dilemma in several ways . Underground facilities are typically energy conserving in their own right. More importantly, by using addition to the obvious benefit o

54、f preserving green space and agricultural land, there is strong evidence that higher urban density can lower fuel resource consumption The Future of Underground Space Development Although existing underground facilities throughout the world provide some models for future development, they are all li

55、mited in scale, in their lack of a comprehensive vision for the total city environment. As a complement to more detailed planning and research studies, it is useful to examine the visions of extensive underground complexes, even entire cities, that have been proposed by futuristic planners and desig

56、ners.Geotech90, a conference and exhibition held in Tokyo in April 1990, was a major forum for the underground industry in Japan. More than a dozen underground concepts were displayed, ranging from the typical transit and utility uses to underground corridors that are envisioned as places for a comm

57、unication network protected during disasters. Such corridors could also effectively transport both waste and energy between substations in the city and central generation and disposal sites outside the city. This approach not only relieves congestion but also can provide more efficient energy genera

58、tion and recycling of waste materials. These concepts are all intended to permit a major upgrade of the city infrastructure that will eventually enable the surface to be rebuilt with more open space and a more efficient, attractive overall environment.When completely new cities are envisioned for th

59、e future, the underground often is a major component, as illustrated by the work of the architect Paolo Soleri over the last 30 years. In science fiction future cities often are depicted as self-contained, climate-controlled units frequently located underground for protection from the elements and pos