Expert: Dr D.Venkat Reddy - 5/7/2007

Question
plz tell me importance of engineering geology in our daily life in detail also if u can give me any link i would appericiate that.

Answer
GEOLOGY IN CIVIL ENGINEERING
BY
Dr D.Venkat Reddy-Geology section .NITK Surathkal-Srinivasanagar-575025-Mangalore -DK
email dvr1952@yahoo.co.in
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You will get information how engineering geology useful in daily life-refer the below mentione data-Dr DVREDDY-NITK-INDIA

   Geology stands to civil engineering in the same relation as faith to works. The success or failure of   onshore and offshore civil engineering structure undertaking depends largely on the physical conditions, which fall within the province, or geology and the works of an engineer should be based on the faith to geologist.
   Engineering geology is the branch of earth science studying the geological conditions of the construction   and utilization of engineering structures. The main practical purpose of engineering geology is to provide solution for safe designing, construction of civil engineering structures.
   The engineering geologist has to observe and record geological information and then translate this data to practical engineering design, construction and maintenance of civil engineering projects.
   The application of geology to civil engineering, that is to the preliminary exploration, design construction, operation and maintenance of engineering structures such as dams, tunnels highways, canals and buildings, results in better and less costly engineering structures. This is because such structures are built on rocks and soils, because rocks and soils frequently are the principal materials of construction, and because all the geological conditions at structures sites influence the engineering problems, which must be surmounted. These things must have geological interpretation before the engineer can choose the most appropriate site and design and build the most appropriate structure (Roger Rhoades, 1946)
    The geological aspects of the civil engineering site have to be studied in detail before commencement of the project. The civil engineer and the engineering geologist have to work together in the field in initial planning stage. In some stages they work separately, in others jointly, based on field and project work requirements. Civil engineers require field training in geology to understand the natural geological conditions and their influence on civil engineering structures/constructions. A civil engineer must be in a position to understand the geological map of the project area with due practical knowledge for assessing the data. Generally, engineering geologist of the project site will approach to the project civil engineer executive to present field geological maps, geological cross-sections of the construction site, borehole data details etc. for taking final approval for commencement of the project. In adverse geological conditions of the project site, geologist   may reject site or suggest for another alternative site on the basis of geological setting of the region. In such alternatives civil engineer executive should be in a position to study all submitted engineering geological data for taking final decision of the project. Civil engineer must take field training in geology to understand geological settings particularly identification of lithological units, outcrop pattern, attitudes of geological formations, field recognition of faulted, displaced zones, assessment of weatherability pattern of the region etc. In addition, he must be in a position to read surface and subsurface geological map of the region. Engineering geology is a multi disciplinary subject having interrelation with other disciplines such as hydrogeology, rock mechanics, soil mechanics, remote sensing, photo grammetry, exploration geology, geophysics, geochemistry, drilling, blasting, etc. A trained civil engineer understands all field geological problems and interpret the submitted geological documents to take further effective action for early clearance or approval or rejection  of the project. Geological Survey of India, Government of India, organization and training division conducts field trainings on various aspects of geology including engineering geology. Few university earth science departments and Geological Society of India also undertakes field geological camps and trainings in selective areas with highly qualified and experienced geologists. In addition All India Council of Technical Education (AICTE), which is a premier body for engineering and technical education in the country, has undertaken up the responsibility of organising the short term training programmes through the premier national level institutions on topics of current interest including engineering geology.

Responsibility and nature of work of civil engineer and geologist in civil engineering projects - in brief
   The function of the engineering geologist to interpret the character of structure sites and prospective natural construction materials, thus supplying information essential-plan and specifications must effectively reconciling the engineering objective with natural conditions (Roger Rhoades, 1946)
   The civil engineer’s responsibility to define what kind of information he needs concerning materials and surface and sub-surface conditions; it is engineering geologist’s responsibility to obtain and interpret that information. The burden of geologic interpretation rests with the geologist; the burden of engineering interpretation and application rests with the engineer. The geologist must assimilate the data and present conclusions and recommendations to the engineer in a concise, practical form. (Roger Rhoades, 1946)  
   Civil engineer and engineering geologist work together in major civil engineering projects in different levels starting from planning stage to construction and maintenance stage. Generally a major civil engineering project site will be selected on the basis of field investigations. The stage in this task starts from reconnaissance stage to construction and maintenance. In a few fields the responsibility of civil engineer and geologist are listed below.

1. Geological Mapping:  Engineering geologist has to prepare a regional geological map of the project site on the basis field studies, of aerial and satellite data interpretation. In selective areas sub-surface geological maps is also required. Geological map of the project site is the first hand document for geologist and civil engineers to take further action for detailed exploration.

2.Exploration: In this stage project geologist will undertake selective exploration techniques for recognition of the geological feasibility and conformation of the site for civil engineering project. Selective geophysical exploration techniques are also utilised for the conformation of sub-surface geological conditions. However, it depends upon the type of the project and nature of the field conditions. In addition detailed petrological, structural, rock mechanical properties of insitu rocks are also conducted in the field for determination of strength properties of rocks.

3.Project Planning: Project planning is the most important aspect in civil engineering. Every civil engineering project requires systematic planning of the project and executive methodologies to be carried out in each stage based on the type of civil engineering works. For instance road planning differs from selecting site for major reservoir. Each type of civil engineering project requires planning that suits the design of the construction. In general, civil engineering executive requires a feasibility report of the project that he wants to undertake. Engineering geologist will prepare a basic project report on the basis of the geological/exploration investigations taking into all field aspects into consideration. In addition civil engineer prepares report based on the technical/geological report and then prepares further project planning schedule taking into civil engineering parameters, finance resources, environmental and ecological considerations and social conditions of the region.

4.Hydrological/Surface water maps: Most of the civil engineering projects require in detailed information about the surface water of the project site. A civil engineer prepares a detailed hydrological map incorporating available surface water conditions of the region. The reservoir/dam construction projects require hydrographs of the river basins before commencement of the work.  Flood data, hydrometeorological data (if available, for the past 100years) to asses the river basin character of past and plan for reservoir in keeping for (100years schedule) for life of the project. The volume of total run-off, drainage characteristics, sedimentary process, wetherability, erosion potential estimate are required before planning for major reservoirs and dams.

5.Hyrogeological Maps: Groundwater is one of the major problems in most of the major civil engineering works, in particularly in tunnel excavation, underground excavations, underground rail lines, underground mining, deep water foundations, oil and natural gas extraction structures, dams and reservoir etc which cut across the groundwater table. Hydrogeological parameters such as porosity, permeability, specific capacity, specific retention, specific yield, aquifer parameters etc. are to be studied in detail before execution of sub-surface civil engineering structures. Groundwater flow depends upon local hydro-geological conditions and structural controls of the region. Generally engineering geologist also prepares structural frequency diagram to asses the movement of subsurface water.

6.Slope Stability/Landslide/Land Slip: Landslides are the major sliding activity of rock or soil mass along slopes. Stability of slopes is the important factor for all civil engineering projects or developmental activities. All slopes have tendency to move. In planning for road network in steep hilly terrains a detailed geological, geomorphological, structural geological map of the terrain required. Geotechnical engineer asses the nature and extent of slide on the basis of strength parameters of the rock mass, and geological, hydrological, meteorological and structural etc. conditions of the terrain before adopting suitable landslide preventive measures.

7.Hydraulic structures/dams & reservoirs: Selection of suitable site for major dams and reservoirs is a major challenge for an engineering geologist. Engineering division, Geological survey of India generally undertakes field geological investigations of major reservoirs/dams in our country. Generally two to three sites are initially selected for projects. Detailed geological, geotechnical and geophysical surveys will be conducted for conforming surface and sub-surface geological conditions of that terrain. Detailed reports will be prepared incorporating all determined field data and submitted to the top civil engineer executive for final approval.  Geological organisation recommends and suggest suitable site based on their investigation.  Civil engineer and geologist will discuss technical details of the site on the basis of the field data. Every report requires in depth study and interpretation of the field data before final selection of the site. In addition, both civil engineer and geologist will conduct insitu test for foundation materials and supervise the construction methods and monitor the structure after completion

8.Seismic hazards/Seismicity: Among the various natural hazards that our earth is subjected to, an earthquake happens to be the most devastating natural impact, resulting in huge loss of human life and materials. More than 650 earthquakes in excess of magnitude 5.0 have been recorded since 1890 in our country. It is estimated that over 50 percent of the Indian mass is subjected to varying degrees of earthquake shocks.  Peninsular India is also vulnerable to earthquake shocks. Major civil engineering constructions require in depth study of the seismcity of site before execution of the project. Geophysists, seismologists and earthquake engineers usually determine the measure to which the seismcity will affect the project site before execution of the work. Presently the entire country seismic zoning maps are available with National Geophysical Research Institute, Hyderabad for user agencies. Presently seismometer, recording instruments, were installed in all major meteorological departments, national seismological observatories at Delhi, Shillong, Pune, Kodiakanal, National Geophysical Research Institute, Bhabha Atomic Research Centre, Wadia Institute of Himalayan Geology and in several other organisations in the country like Geological Survey of India, Central Water and Power Research Station, and state governments in Maharashtra, Karnataka, Gujurat, Andhrapradesh, Assam, Uttar Pradesh and in few universities. Few more seismic recording stations are under different stages of construction in specified locations in our country.

9.Environmental Impact Assessment: Each   civil engineering project must get ecological clearance from the government. It is a must for state government/central government civil engineering divisions to get approval of Department of Environment and Forest, before commencement of the project. Each project must accompany a detailed environmental assessment report incorporating environmental and ecological aspects of the region before construction of the civil engineering structure. In addition, a detailed precautionary or preventive measure for reduction on the environment and reclamation measures also to be incorporated. Civil, environmental and geotechnical engineer and engineering geologist are required to study all ecological problems of the region before starting of the project and also the expected ecological problems after the completion of the project and suggestive remedial measures to protect the environment of the region.
   The civil engineer and engineering geologist must work together in field from the reconnaissance stage to the completion of the project in different stages with good co-ordination to identify the field problems and suggest possible remedial measures in case of specific geo-engineering problems.

Development and use of engineering geology and geotechnology in India-in brief
  In India, the great epic of Mahabharata, Vedas and other ancient classical literature                 contain numerous references about irrigation and water supply. Archaeological remains of innumerable temples, canals and tanks bear ample testimony to the high skill of engineering and application of geological knowledge as understood then in ancient India.
  In India, the earlier known application of geotechnology to the construction of buildings is the ‘Taj Mahal’, built during the period of 1632-1650, in which the principle of transfer of load to depth, using piles has been successfully utilised. Thus, this monument has been built on cylindrical well foundation sunk into the soil at close intervals. The soundness of the design is time testified, since even after four centuries of its existence, the lines and angles of the structure are as accurate as they were on production.
  Thomas Oldham of the Geological Survey of India is considered as one of the pioneering engineering geologist. He had analysed, as early as in 1852, the geological factors influencing the choice of the proposed railway alignment between Calcutta and Patna, a distance of 500 kms.
  India was one of the few countries in the world that had appreciated the value of applying geological principles to engineering problems as early as in the second half of the 19th century. Since the last part of 19th century, the responsibility of engineering geology investigations in India has solely rest with Geological Survey of India (G.S.I.), the pioneer organisation engaged in the pursuit of geological sciences.
  R. D. Ohdman of G. S. I undertook studies on effects of earthquake phenomena on civil engineering structures first time in our country. In the late 19th century, which laid the foundation of engineering and seismology. Oldman studied the Great Assam Earthquake of 12th June 1897. He published catalogue of Indian earthquakes from the earliest times to the end of 1896 A.D. the first seismograph in India was installed by Moosal-Bombay in 1869. The Indian Meteorological Department (IMD) set up a network of seismological observations at Simla, Calcutta, Kodiakanal, Agra and Hyderabad. In India the activities in the field of geophysics began in 1947.
  The geophysical research wing at the Geological Survey of India, Calcutta came into existence from 1961. The wing was then transferred to the Council for Scientific and Industrial Research (CSIR) in 1964 and was renamed as the National Geophysical Research Institute (NGRI). The institute then transferred to Hyderabad, Andhrapradesh. Ever since from its inception NGRI has taken bridge site investigations throughout the country.
  A strategic branch of geology was opened within GSI in 1942 to look after the problems related to defence requirements of the country. A full-fledged branch dealing with Engineering Geology and Groundwater was established in 1945 under the leadership of J. B. Auden, who was responsible fro laying the modern practice of engineering geology used in our country. Many sub divisions were established in 1957 at regional centres of GSI to meet the increasing demand in the field of engineering geology.
  The methods, techniques and tools of engineering geological investigations vastly improved during the period 1950 – 1980. Standardisation of the methodology and techniques of geotechnical investigations of river valley projects has been generated during this period by the Indian Standards. Facilities for research and teaching in engineering geology and geotechnology have increased in Indian universities and institutions and special technological centres dealing earthquake resistant design and construction of structures, roads and building constructions have been established (Krishnaswamy, 1982).
  A group of interested geologists from Australia, France, India, Turkey and United States of America, who had gathered for the 22nd International Geological Congress in 1964 formally accepted to form International Association of Engineering Geology. The association is a non-government, independent body that is free from political influence and governmental policies. Its objectives are to generate research; to diffuse knowledge; and to promote international co-operation in the field of engineering geology for the benefit of mankind and to support and encourage the exchange of views on the application of the science of geology for the engineering constructions and industrial activities.
  The Indian Society of Engineering Geology founded in 1965 and actively conducting several conferences, symposia relating different types of engineering development in the country. ISEG has been publishing journal of Engineering Geology.

   Various geoscientists have reviewed the engineering geological problems and development of engineering geology and geotechnology in India. Among few experts are Balasundaram and Rao (1972) who studied the history and development of engineering geology in India; Hukku, Raju and Sarama (1972) dealt with the problems of engineering geology in India; Krishnaswamy (1972) dealt with systematic geotechnical studies in the country; Ramachandran and Gangopadhyaya (1972) studied engineering geological features of soft rock areas; Srinivasan, Chalapathi Rao and Bansode (1972) and Ray, Mehta and Ashraf (1972) studied construction materials available in India and their utilisation in engineering problems in recent years (till date)

Departments dealing the subject:
   Engineering division of Geological Survey of India is actively involved and being involving various major civil engineering projects in different geological terrains in our country.
Engineering and geotechnical division had been modernised and procured all latest equipments, instrumentation and computational devises to take difficult geological problem to solve the them and to suggest it to the civil engineer from the planning stage to construction maintenance stage. In addition, technical study is also carried out in marine geotechnology. Marine wing of Geological Survey of India is looking all marine geotechnical problems and mapping of ocean floor. GSI is giving technical assistance and consultancy to state government agencies, other required firms after getting approval from Director general, GSI. Standard geological map of India, mineral and geological map of each state, engineering geological maps of major dams and reservoirs, other civil engineering sites etc. were prepared by this organisation. Required user agencies, research scholars, students, faculty those involved in the field of engineering geology, civil engineering, geotechnical engineering and earth science fields can get these published maps and reports after getting permission from director general GSI.
    A separate Granite Dimension Stone cell also established by GSI for preparation of basic granite and ornamental stone deposit maps of different states. This unit of GSI already prepared the commercial ornamental rock deposits of many states. Detailed reserves and resources of commercial rocks data and maps are available for user agencies. India is one of the leading exporters of granite/ornamental rocks to the other countries. For technical consultancy and procurement of geological maps, reports etc one can contact Director General, Geological Survey of India, 27 Jawaharlal Nehru Road, Calcutta-700016, e-mail: gsi@gems.vsnl.net.in
   In addition Department of Science and Technology collaborated organisations, Indian Institute of Technologies, National Institute of Technologies (former Regional Engineering Colleges), Anna University, Centre for Geo Engineering, other university earth science departments are also involved in the research and development fields of engineering geology, marine geotechnology, commercial rock deposits. Department of Ocean Development Central government, established National Institute of Ocean Technology, Chennai, Tamil Nadu for carry out exclusive study of marine /ocean technology in the field of marine structures oceanography, marine engineering and geological investigations, marine archaeological investigations. NIOT also funds to carrying out the research and development in the field of thrust areas in the ocean technology and related areas. Research scholars, faculty, technical universities to contact the Director, National Institute of Technology, (IIT Chennai campus), Chennai-600036, Tamil Nadu or the   Secretary, Department of Ocean Development, Govt of India, New Delhi.  
   The National Institute of Rock Mechanics (NIRM) is one of the premier institutes for rock mechanics studies and design of excavations. Recently a granite mining cell, first of its kind in the country, has been set-up at NIRM by the Ministry of Mines to assist the granite industry for scientific exploration. NIRM will provide all scientific and technical services for characterisation of the deposits and scientific design of quarries for granite/dimensional stones. The rock testing facilities are available at the institute of international standards and these are being augmented to meet the diverse requirement of the industry. NIRM also undertakes civil engineering project investigations, tunnel excavations, reservoirs, dams, canal works, drilling and blasting designs of civil engineering sites. Civil/miming/earth science students, research scholars, faculty, private and public organisations who require the technical know how of in the field of rock mechanics can contact the organisation to get more information. Contact address is Director, National Institute of Rock Mechanics, PO: Champion Reefs, Kolar Gold Fields-563 117, Karnataka. Email:  nirm@giasbgo1.vsnl.net.in.
   University Grants Commission (UGC); Department of Science and Technology(DST); Engineering and Science division, Science and Technology division, Ministry of Human Resource Department(MHRD);  Research and development division, All India  Council for Technical Education (AICTE); are some of the agencies that are giving financial supports to the research projects in the field of thrust  areas of geo-engineering, exploration methods in geo resources evaluation, material engineering, civil and geotechnical engineering. These organisations frequently change their policies keeping in view of our country priorities.  In UGC, DST and AICTE recently few schemes are drafted for benefiting to students to get financial assistance for higher education, research funding and the interested students and research faculty can download more information from the respective websites. In addition, many other central government organisations also actively supporting by funding the research projects in the field of engineering geology, geotechnical engineering and environmental geotechnical engineering. Few international   research-funding agencies are also supporting the developing countries in the field of engineering and geotechnology.

Few case studies:
  The knowledge of engineering geology and geotechnology play vital role in civil engineering projects (Venkat Reddy, 1995). Few of the typical Indian examples, which throw light on the knowledge of engineering geology of Indians, are listed below (extracts from Krishnaswamy et. al. 1974 & 1982)  
1.   The longest dam in the world is at Hirakud, Orissa, with 5 kilometres of main dam made of concrete/masonry/earth and about 20 km of low earthen dykes to form the reservoir. Geological investigation was carried out before the construction of dam started in 1948. The dam was completed in 1957. The project area exposed the Archaean metamorphic rocks, sedimentaries belonging to Gondwanas and Cuddapahs and post-Cuddapah intrusives. In the right concrete dam area, the 150 m wide fault zone between the Archaeans and Cuddapahs lay towards the right extremity of the power dam section and continued transversely over the entire foundation area. The entire fault zone excavation was done under difficult execution conditions. Consolidated grouting of the mylonites in the fault zone was carried out over the entire dam base. To control heavy seepage in the power plant foundation 20 tons of cement were injected.
2.   One of the very high straight gravity concrete dam in the world – Bhakra, Himachal Pradesh – founded on soft rocks and medium hard rocks which were riddled with fault zones cutting across the foundations and abutments in different attitudes. Geological investigations of the project were carried out and construction was carried out during 1948 – 1963. The remedial treatment to the problems incurred with was depended on the nature, orientation and extent and position of the structure causing that problem in the foundation.
3.   One of the fairly high cyclopean dams in the world, constructed across river Koyna at Deshmukhwad, Maharastra, survived a major earthquake that was very close to that location. Minor horizontal and vertical hairline cracks were noticed in the dam and the dam then strengthened by grouting pre-stressed anchoring and enlargement of the dam section by concrete backing in 1969-70. Geological investigation of the project started in 1956 and the dam was completed in 1961.
4.   The first major arch dam constructed in our country lies in Idukki, Kerala. Charnockites and associated granites, pegmatites and biotite hornblede gneisses of Peninsular Gneissic Complex (Archaean) constitute the main rock type of the area. The v-shaped Idukki gorge with a chord-high ratio of 2:1 and massive rocky abutments with no major adverse geological features offers a natural site for an arch dam. Geological investigation at the project site started prior to commencement of contruction in 1966. The dam was completed in the year 1974.
5.   The highest stone-masonry dam in the world – the Nagarjuna Sagar, Andhra Pradesh – has been constructed across the river Krishna. The rock type exposed at the dam site and its vicinity are the granitic gneisses of the Peninsular Gneissic Complex (Archaean) overlain unconformably by   quartzites and hales of the Srisailam Group of the Cuddapah Super Group. The project area lies very close to the eastern faulted contact of Archaeans and Cuddapah sediments. The main geotechnical problem encountered at the dam site relates to treatment of fault and shear zones in the granites exposed at the foundation and treatment of sedimentaries on the abutments to render them watertight. The construction of the Nagarjunsagar multipurpose project was taken up in 1956 and the project was completed in 1965. The GSI Engineering Geology division carried out the geotechnical investigations throughout the construction stage.
6.   The Srisailam dam has been constructed across Krishna River, the second largest river in the peninsular India. The Srisailam dam is located on the extreme northwestern corners of the Cuddapah basin. At the dam site, the quartzites and interbedded shale lie deceptively flat and undisturbed. However, older argillaceous sediments occurring around the dam site are exposed in a highly disturbed and contoured state having been repeatedly folded and faulted. Few portions posed problems of settlement and sliding. The remedial measures were adopted against sliding were to mobilise the frictional resistance on either side of the deep channel by slightly arching the axis of the dam. The physical characteristics of the bedrock units are determined to establish strength characters. GSI had been associated with the geotechnical investigations of the project from time to time (Mahendra, 1974)
7.   One of the earliest earthen cum masonry dam in India at Ukai, Gujarat. The entire dam site area is covered by a thick clay overburden and subsurface geology in the area had deciphered from 390 borehole aggregation to 11.7 km were drilled for evaluation of subsurface geological structures and bedrock configuration. En-echelon shear zones 15 to 90 m wide occur at the dam site. The earth dam section occurred seepage through foundation, particularly along the shear ones and riverbed. Geotechnical investigations were carried out extensively and to minimise seepage through the shear zones, which extend into the reservoir, chemical grouting employed sodium silicate – monosodic phosphate sodium silicate – aluminate grout mixes was carried out. GSI, Engineering Geology division carried out geological/geotechnical investigations prior to commencement of construction in the year 1964. The dam was completed in 1972
8.   One of the longest inter-river diversions in the world, the Beas-Sutlej Link Project (Pondoh dam) has been constructed across Beas River near Pondoh in Mandi District, Himachal Pradesh, for diverting the water from Beas to Sutlej River along a 33.7 km. long tunnel. Some portion of the tunnel had to negotiate very difficult flowing and squeezing conditions. Special tunnelling techniques were adopted in crushed kaolinised area and crushed granites and adequate drainage was provided with grouting. Geological investigations at the project site started prior to the commencement of construction in the year 1965. The dam was completed in 1977.
9.   One of the successful reservoirs on fairly cavernous Precambrian limestone is at Obra dam, Uttarpradesh. The Obra dam was constructed on the shale with interbeds of limestone underlying the Kajrahat limestones. The existence of solution cavities in the limestone interbeds within the shale occurring in the foundations and the Kajrahat limestone in the reservoir gave rise to twofold problems of settlement of the foundations of civil engineering structures and leakage of the reservoir water from the dam foundation and through the left and right rims of the reservoir. Elaborate remedial treatment was resorted to tackle reservoir leakage, piping, settlement and sliding of the foundation such as grout curtain has been provided along the concrete rock main dam, below the bedrock. No significant post-construction problem has been recorded so far during the last 25-30 years of the operation. Geological and geotechnical investigations at the project site were carried out prior to construction in 1964.

References and further reading:   

Balasundaram, M. S, and G.S.M. Rao (1972) History and development of engineering geology,
   India Records, GSI, 104 (2), pp 1-22
Engineering geology case histories (1975) GSI miscellaneous publication, Calcutta, No.
   29, Part I.
Geotechnical features of major dams in India (1982). International association of
   engineering geology, New Delhi.
Hukku, B. M., K. C. C. Raju and S. B., Sarma (1972) Problems of engineering geology, India
    Records,GSI,104(2), pp 31-44.
Krishnaswamy, V. S. (1974) History and development of engineering geology and
   geotechnics, Mimeographed report, proceedings of summer school, History of
   science. Indian national science academy, New Delhi.
Krishnaswamy, V.S. (1982) History and development of engineering geology and geotechnology
   in India. Proc. Internat. Assoc. Engineering Geology, vol. VIII, pp. 361-369.
Legget (1978) Cities and geology.
Mahendra, A. R. (1974) The low shear strength foundations and design of Srisailam dam,
   A. P., India. Proceedings of International association of engineering geology,
   Brazil, P iiii 25.1 – 25.10.
Ramachnadran, B. and B. Gengopadhyaya (1972) Engineering geological features of soft rock
   areas. Indian Records, GSI, 104 (2), pp. 65-84.
Roger Rhoades (1946) Geology in Civil Engineering, Second Pan American Congress of Mining
   Engineering and Geology, Bureau of Reclamation, United States department of the
   Interior, pp 1-10.
Srinivasan, P.B., R.V. Chalapathi Rao and R. S. Bansode (1972) Engineering geological
    problems of hard rock areas. Indian Records, GSI 104 (2), pp 45-64.
Venkat Reddy, D. (1995) Engineering geology for civil engineers. Oxford and IBH
    Publishers, New Delhi.