《工程地質(zhì)》緒論

1、 一，工程地質(zhì)學(xué)的定義及任務(wù) 工程地質(zhì)學(xué)：工程地質(zhì)學(xué)是研究與人類工程建筑活動有關(guān)的地質(zhì)問題的學(xué)科，是地質(zhì)學(xué)的一個分支。 工程地質(zhì)學(xué)的目的在于查明建設(shè)地區(qū)或建筑場地的地質(zhì)條件，分析、預(yù)測和評價可能存在和發(fā)生的工程地質(zhì)問題，及其對建筑物和地質(zhì)環(huán)境的影響和危害，提出防治不良地質(zhì)現(xiàn)象的措施，為保證工程建設(shè)的合理規(guī)劃、建筑物的正確設(shè)計、順利施工和正常使用，提供可靠的地質(zhì)科學(xué)依據(jù)。 美國地質(zhì)研究所的定義：engineering geology is the application of the geological sciences to engineering practice for the purp

2、oses of assuring that the geologic factors affecting the location, design, construction, operation and maintenance of engineering works are recognized and adequately provided for. 美國更一般的定義是：Engineering Geology is the application of geology to human endeavor and projects. It is that field of applied

3、geology which relates to investigation and analysis of the geologic basis for safe and appropriate design, construction, and operation of engineering works. It includes providing a geologic rationale for locating structures, land use planning, conservative use of ground water, and waste disposal. En

4、gineering Geology activities are therefore paramount in public health, safety and welfare, and in safeguarding the geologic aspects of the environment. 工程地質(zhì)學(xué)主要研究建設(shè)地區(qū)和建筑場地中的巖體、土體的空間分布規(guī)律和工程地質(zhì)性質(zhì)，控制這些性質(zhì)的巖石和土的成分和結(jié)構(gòu)，以及在自然條件和工程作用下這些性質(zhì)的變化趨向；制定巖石和土的工程地質(zhì)分類。 工程地質(zhì)學(xué)要分析和預(yù)測在自然條件和工程建筑活動中可能發(fā)生的各種地質(zhì)作用和工程地質(zhì)問題，例如：地震、滑坡、

5、泥石流，以及誘發(fā)地震、地基沉陷、人工邊坡和地下洞室圍巖的變形，因破壞、開采地下水引起的大面積地面沉降、地下采礦引起的地表塌陷，及其發(fā)生的條件、過程、規(guī)模和機制，評價它們對工程建設(shè)和地質(zhì)環(huán)境造成的危害程度。研究防治不良地質(zhì)作用的有效措施。 工程地質(zhì)學(xué)包括工程巖土學(xué)、工程地質(zhì)分析和工程地質(zhì)勘察三個基本的部分。 工程巖土學(xué)是研究巖土的工程地質(zhì)性質(zhì)、性質(zhì)的形成及它們在自然和人類活動影響下的變化。 工程地質(zhì)分析是研究工程活動的主要地質(zhì)問題，研究這些問題產(chǎn)生的地質(zhì)條件、力學(xué)機制和發(fā)展規(guī)律，以便正確評價并提出相應(yīng)的防治措施。 工程地質(zhì)勘察的任務(wù)是探討調(diào)查研究方法，查明有關(guān)工程活動的地質(zhì)因素，調(diào)查研究和分析評

6、價建筑場地和地基的工程地質(zhì)條件，為建筑選址、設(shè)計、施工提供基本資料。 另外還包括區(qū)域工程地質(zhì)學(xué)，環(huán)境工程地質(zhì)學(xué)。 工程地質(zhì)學(xué)密切相關(guān)的主要學(xué)科有： 巖石力學(xué)、土力學(xué)、工程力學(xué)、地質(zhì)力學(xué)、構(gòu)造地質(zhì)力學(xué)、巖石學(xué)、礦物學(xué)、水文地質(zhì)學(xué)、動力地質(zhì)學(xué)、地貌學(xué)、第四紀地質(zhì)學(xué)、地史學(xué)等。 工程地質(zhì)學(xué)的基本任務(wù)是查明工程建筑的地質(zhì)條件，保障工程建筑物的安全和正常運轉(zhuǎn)。 工程地質(zhì)條件：是指與工程建設(shè)有關(guān)的地質(zhì)條件的總和，它包括土和巖石的工程性質(zhì)、地址構(gòu)造、地貌、水文地質(zhì)、地質(zhì)作用、自然地質(zhì)現(xiàn)象和天然建筑材料等方面。 工程地質(zhì)學(xué)的研究方法：首先是自然歷史分析法，然后在此基礎(chǔ)上輔以力學(xué)分析法、實驗法和類比法。 工程地

7、質(zhì)工作者往往在地質(zhì)方面或在工程方面曾接收過基本訓(xùn)練，而且似乎一般公認這兩種訓(xùn)練方式各有其優(yōu)缺點，K.約翰（Klaus John，1974）很好地總結(jié)了一般的感受：地質(zhì)學(xué)家喜歡直接地、或間接地探索一個問題，且一般說來使用定性的術(shù)語，往往傾向于將探討問題置于比得出結(jié)果更為優(yōu)先的地位，強調(diào)問題的復(fù)雜性，而對問題的簡化只能遲疑地接收；而工程師的情況是為了能對一個問題進行數(shù)值分析，往往有過分不適當?shù)暮喕瘍A向，他們受過依據(jù)理論分析問題的訓(xùn)練，因而他們信賴數(shù)據(jù)，信賴自然條件的抽象化，這是由于教育和環(huán)境的影響，他們受到重視結(jié)果的思想支配。 工程地質(zhì)學(xué)產(chǎn)生于地質(zhì)學(xué)的發(fā)展和人類工程活動經(jīng)驗的積累中。17世紀以前，

8、許多國家成功地建成了至今仍享有盛名的偉大建筑物，但人們在建筑實踐中對地質(zhì)環(huán)境的考慮，完全依賴于建筑者個人的感性認識。17世紀以后，由于產(chǎn)業(yè)革命和建設(shè)事業(yè)的發(fā)展，出現(xiàn)并逐漸積累了關(guān)于地質(zhì)環(huán)境對建筑物影響的文獻資料。第一次世界大戰(zhàn)結(jié)束后，整個世界開始了大規(guī)模建設(shè)時期。1929年，奧地利的太沙基出版了世界上第一部工程地質(zhì)學(xué)；1937年蘇聯(lián)的薩瓦連斯基的工程地質(zhì)學(xué)一書問世。50年代以來，工程地質(zhì)學(xué)逐漸吸收了土力學(xué)、巖石力學(xué)和計算數(shù)學(xué)中的某些理論和方法，完善和發(fā)展了本身的內(nèi)容和體系。在中國，工程地質(zhì)學(xué)的發(fā)展基本上始自50年代。 我國歷史悠久，人民勤勞智慧，修建了許多舉世聞名的大型工程： 鴻溝公元前722

9、年，自河南榮陽，引黃入淮； 伍堰公元前506年，在江蘇高淳縣，溝通太湖與長江； 長城和都江堰，都修建于戰(zhàn)國時期，距今2000多年。 上世紀五十年代以來，我國工程地質(zhì)學(xué)得到了飛速的發(fā)展。 數(shù)以百計的巨型大壩：新安江、新豐江、三門峽、劉家峽、青銅峽、葛洲壩、三峽等。 鐵路、地鐵。 核電站。 橋梁。 我國幅員遼闊，有不同活動程度和發(fā)展趨勢的大地構(gòu)造單元，有不同性質(zhì)的自然地理區(qū)域。 北方：黃土； 南方：紅土、膨脹性和裂隙發(fā)育的粘土。 巖溶。 工程地質(zhì)學(xué)主要解決兩個方面的問題： 一是區(qū)域穩(wěn)定問題； 二是地基穩(wěn)定問題。 具體概括起來主要解決以下問題: The investigation of founda

10、tions for all types of major structures, such as dams, bridges, power plants, airports, large buildings, and towers; The evaluation of geologic conditions along tunnel, pipeline, canal, railway, and highway routes; The exploration and development of sources of rock, soil and sediment for use as cons

11、truction material; 1.The investigation and development of surface and groundwater resources; groundwater basin management; protection and remediation of groundwater resources; 5. Evaluation of geologic conditions (including groundwater) affecting residential, commercial, and industrial land use and

12、development; 6. Construction geology, including slope stability, dewatering, subdrains, grouting considerations, and excavatability; 7. Safe disposal of waste to the Earth; 8. The evaluation of geologic hazards such as landslides, faults and earthquakes, radon, asbestos, subsidence, expansive and co

13、llapsible soils, expansive bedrock, cavernous rock, and liquefaction; 9. Engineering Geologists participate in land-use planning, environmental impact report research, mined land reclamation, timber harvest planning, and insurance and forensic investigations. 二，工程地質(zhì)在土木工程中的作用1，建筑場地與地基的概念建筑場地是占有指工程建設(shè)所

14、直接并使用的有限面積的土地，大體相當于廠區(qū)、居民點和自然村的區(qū)域范圍的建筑物所在地。建筑物地基是指由于承受由基礎(chǔ)傳來的建筑物荷載而使土層或巖層一定范圍內(nèi)原有應(yīng)力狀態(tài)發(fā)生改變的土層或巖層。基礎(chǔ)建筑物地面以下擴大的以減少建筑物與土層或巖層接觸部分壓力的結(jié)構(gòu)。 地基包括持力層和下臥層。 持力層是指直接與基礎(chǔ)接觸的土層。 下臥層是指持力層下部的土層。 天然地基是指未經(jīng)加固處理、直接支撐基礎(chǔ)的地基。 軟地基是指地基主要由淤泥、淤泥質(zhì)土、松散的砂土、充填土、雜填土或其他高壓縮性土層所構(gòu)成。 人工地基當?shù)鼗翆虞^軟，建筑物的荷重又較大時，需要對地基進行人工加固處理，這種地基稱為人工地基。 2，工程地質(zhì)在土木

15、工程中的作用 重大工程建設(shè)中出現(xiàn)的災(zāi)害性事故與工程地質(zhì)有著很大的比例。 據(jù)不完全統(tǒng)計，一百年來，世界上僅水壩這一種建筑物破壞事件就發(fā)生了500多起，其中相當大的比例是由地質(zhì)原因造成的。1)，ST. FRANCIS DAMbuilt by the City of Los Angeles Bureau of Water built by the City of Los Angeles Bureau of Water Works and Supply in 1925-26 as a curved Works and Supply in 1925-26 as a curved concrete gra

16、vity dam, approximately 600 feet concrete gravity dam, approximately 600 feet long, 200 feet high in San Francisquito Canyon, long, 200 feet high in San Francisquito Canyon, about 5 miles northeast of what is now Magic about 5 miles northeast of what is now Magic Mountain, California. Mountain, Cali

17、fornia. The dam The dam with a 12.5 billion-gallon capacity failed failed catastrophically upon its first full filling, near catastrophically upon its first full filling, near midnight on March 12/13, 1928 , smidnight on March 12/13, 1928 , sending a 180-foot-high wall of water crashing down San Fra

18、ncisquito Canyon, , killing at least 450 people killing at least 450 people in the San Francisquito and Santa Clara River in the San Francisquito and Santa Clara River valleys. it was the greatest American civil valleys. it was the greatest American civil engineering failure in the twentieth century

19、. engineering failure in the twentieth century. The right abutment (foundation) of the dam was in mica schist, which is landslide-prone, and the left abutment was in red sandstone and conglomerate. The contact between the two rock types was an inactive fault zone of crushed rock about five feet thic

20、k. Later it was found that the fault zone and the sandstone contain considerable gypsum, which is soluble in water. Indeed, these were not desirable foundation conditions for a dam. No geologic examination was performed before the dam was built, and therefore the fault was not identified, but the ro

21、cks were tested dry and found to have adequate strength. 2), Vaiont Dam The Vaiont dam, at the time the tallest concrete arch dam in the world at some 260 m high, was built at the entrance to a very narrow and deep valley tributary to the Piave river valley in the Tyrolean Alps of NE Italy. As the v

22、alley filled with water after completion of the dam in 1960, an ancient landslide on its upper southern side, adjacent to the dam, began to move again, in episodes of slow creeping movement. It was later established that this was due to groundwater, unable to escape into the floor of the now - flood

23、ed valley, saturating a layer of clay within the rocks beneath it. This accumulation of water high in the slope was most marked during periods of heavy rain, although the association of heavy rainfall and creep went unnoticed. However, the presence of the impermeable clay layer in the bedrock was al

24、so not recognized at the time and it was assumed that the movement was due to local saturation of the rocks below the level of water in the reservoir, at the toe of the creeping landslide, rather than accumulation of water pressure in the entire mountainside. It was therefore proposed to regulate th

25、e movement of the landslide, and thus allow it to settle to a new equilibrium, by lowering the level of water in the lake when an episode of creep was in progress, until the toe of the landslide was no longer saturated and the creeping stopped The reservoir was then allowed to refill and the drainag

26、e cycle repeated whenever creeping movement occurred again. Remarkably, the dam withstood the weight of rock piling up behind it and it remains largely intact to this day. However, the landslide displaced as much as 50% of the water within the lake: a tsunami wave traveled east up the reservoir, dest