《工程地质》绪论

1、 一，工程地质学的定义及任务 工程地质学：工程地质学是研究与人类工程建筑活动有关的地质问题的学科，是地质学的一个分支。 工程地质学的目的在于查明建设地区或建筑场地的地质条件，分析、预测和评价可能存在和发生的工程地质问题，及其对建筑物和地质环境的影响和危害，提出防治不良地质现象的措施，为保证工程建设的合理规划、建筑物的正确设计、顺利施工和正常使用，提供可靠的地质科学依据。 美国地质研究所的定义：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. 美国更一般的定义是：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. 工程地质学主要研究建设地区和建筑场地中的岩体、土体的空间分布规律和工程地质性质，控制这些性质的岩石和土的成分和结构，以及在自然条件和工程作用下这些性质的变化趋向；制定岩石和土的工程地质分类。 工程地质学要分析和预测在自然条件和工程建筑活动中可能发生的各种地质作用和工程地质问题，例如：地震、滑坡、

5、泥石流，以及诱发地震、地基沉陷、人工边坡和地下洞室围岩的变形，因破坏、开采地下水引起的大面积地面沉降、地下采矿引起的地表塌陷，及其发生的条件、过程、规模和机制，评价它们对工程建设和地质环境造成的危害程度。研究防治不良地质作用的有效措施。 工程地质学包括工程岩土学、工程地质分析和工程地质勘察三个基本的部分。 工程岩土学是研究岩土的工程地质性质、性质的形成及它们在自然和人类活动影响下的变化。 工程地质分析是研究工程活动的主要地质问题，研究这些问题产生的地质条件、力学机制和发展规律，以便正确评价并提出相应的防治措施。 工程地质勘察的任务是探讨调查研究方法，查明有关工程活动的地质因素，调查研究和分析评

6、价建筑场地和地基的工程地质条件，为建筑选址、设计、施工提供基本资料。 另外还包括区域工程地质学，环境工程地质学。 工程地质学密切相关的主要学科有： 岩石力学、土力学、工程力学、地质力学、构造地质力学、岩石学、矿物学、水文地质学、动力地质学、地貌学、第四纪地质学、地史学等。 工程地质学的基本任务是查明工程建筑的地质条件，保障工程建筑物的安全和正常运转。 工程地质条件：是指与工程建设有关的地质条件的总和，它包括土和岩石的工程性质、地址构造、地貌、水文地质、地质作用、自然地质现象和天然建筑材料等方面。 工程地质学的研究方法：首先是自然历史分析法，然后在此基础上辅以力学分析法、实验法和类比法。 工程地

7、质工作者往往在地质方面或在工程方面曾接收过基本训练，而且似乎一般公认这两种训练方式各有其优缺点，K.约翰（Klaus John，1974）很好地总结了一般的感受：地质学家喜欢直接地、或间接地探索一个问题，且一般说来使用定性的术语，往往倾向于将探讨问题置于比得出结果更为优先的地位，强调问题的复杂性，而对问题的简化只能迟疑地接收；而工程师的情况是为了能对一个问题进行数值分析，往往有过分不适当的简化倾向，他们受过依据理论分析问题的训练，因而他们信赖数据，信赖自然条件的抽象化，这是由于教育和环境的影响，他们受到重视结果的思想支配。 工程地质学产生于地质学的发展和人类工程活动经验的积累中。17世纪以前，

8、许多国家成功地建成了至今仍享有盛名的伟大建筑物，但人们在建筑实践中对地质环境的考虑，完全依赖于建筑者个人的感性认识。17世纪以后，由于产业革命和建设事业的发展，出现并逐渐积累了关于地质环境对建筑物影响的文献资料。第一次世界大战结束后，整个世界开始了大规模建设时期。1929年，奥地利的太沙基出版了世界上第一部工程地质学；1937年苏联的萨瓦连斯基的工程地质学一书问世。50年代以来，工程地质学逐渐吸收了土力学、岩石力学和计算数学中的某些理论和方法，完善和发展了本身的内容和体系。在中国，工程地质学的发展基本上始自50年代。 我国历史悠久，人民勤劳智慧，修建了许多举世闻名的大型工程： 鸿沟公元前722

9、年，自河南荣阳，引黄入淮； 伍堰公元前506年，在江苏高淳县，沟通太湖与长江； 长城和都江堰，都修建于战国时期，距今2000多年。 上世纪五十年代以来，我国工程地质学得到了飞速的发展。 数以百计的巨型大坝：新安江、新丰江、三门峡、刘家峡、青铜峡、葛洲坝、三峡等。 铁路、地铁。 核电站。 桥梁。 我国幅员辽阔，有不同活动程度和发展趋势的大地构造单元，有不同性质的自然地理区域。 北方：黄土； 南方：红土、膨胀性和裂隙发育的粘土。 岩溶。 工程地质学主要解决两个方面的问题： 一是区域稳定问题； 二是地基稳定问题。 具体概括起来主要解决以下问题: 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，工程地质在土木工程中的作用1，建筑场地与地基的概念建筑场地是占有指工程建设所

14、直接并使用的有限面积的土地，大体相当于厂区、居民点和自然村的区域范围的建筑物所在地。建筑物地基是指由于承受由基础传来的建筑物荷载而使土层或岩层一定范围内原有应力状态发生改变的土层或岩层。基础建筑物地面以下扩大的以减少建筑物与土层或岩层接触部分压力的结构。 地基包括持力层和下卧层。 持力层是指直接与基础接触的土层。 下卧层是指持力层下部的土层。 天然地基是指未经加固处理、直接支撑基础的地基。 软地基是指地基主要由淤泥、淤泥质土、松散的砂土、充填土、杂填土或其他高压缩性土层所构成。 人工地基当地基土层较软，建筑物的荷重又较大时，需要对地基进行人工加固处理，这种地基称为人工地基。 2，工程地质在土木

15、工程中的作用 重大工程建设中出现的灾害性事故与工程地质有着很大的比例。 据不完全统计，一百年来，世界上仅水坝这一种建筑物破坏事件就发生了500多起，其中相当大的比例是由地质原因造成的。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