A. Topographic/surface methods.

Regional Geologic and Site Reconnaissance Investigations

Regional geologic and site reconnaissance investigations are made to develop the project regional geology and to scope early site investigations.

The initial phase of a geologic and site reconnaissance investigation is to collect existing geologic background data through coordination and cooperation from private, State, and local agencies.

 

Geologic information collected and analyzed to determine its validity and identify deficiencies недостатки.

Geologic data should also be analyzed to determine additional data requirements, such as ground water and seismicity, that will require advance planning and early action.

A geologic field reconnaissance should be conducted to examine important geologic features and potential problem areas identified during collection of background data.

Field observations are used to supplement background data and identify the need to collect additional data.

 

a. Geologic model. Geologic background and field data should be used to construct a geologic model for each site. The model, which will require revisions as additional information is obtained, should indicate possible locations and types of geologic features that would control the selection of project features.

 

Preliminary geologic, seismic, hydrologic, and economic studies should be used to indicate the most favorable sites before preliminary subsurface investigations are started. Proper coordination and timing of these studies, and incorporation into a GIS, can minimize costs and maximize confidence in the results.

 

b. Small projects. Many civil works projects are too small to afford a complete field reconnaissance study.

For smaller projects, emphasis should be placed on compilation and analysis of existing data, remote sensing imagery, and subsurface information derived from on-site drilling and construction excavations.

A geologist or geotechnical engineer should be available to record critical geotechnical information that comes to light during investigations.

An extensive photographic and video record taken by personnel with some background in geology or geotechnical engineering can serve as a reasonable proxy for onsite investigations.

 

шлих - heavy mineral concentrate,
шлиховое опробование - heavy mineral concentrate sampling,
россыпь, россыпное месторождение - placer, placer deposit

ПЗ-4 Map Studies and Remote Sensing Methods

Map Studies

Various types of published maps, such as topographic, geologic, mineral resource, soils, and special miscellaneous (смешанный; разнообразный ) maps, can be used to obtain geologic information and develop regional geology prior to field reconnaissance and exploration work.

a. Project base map. Spatial components typically used to define a GIS referenced base map include: topographic maps, aerial photographs (digital orthophotos), monumentation/survey control maps, surface/subsurface geology maps, land use maps, bathymetry maps, and various forms of remotely sensed data. Project-specific planimetric maps, digital terrain models (цифровые модели рельефа DTMs), and digital elevation (высота) models (DEMs) are produced through photogrammetric methods and can be generated using a GIS. A DTM may be used to interpolate and plot a topographic contour map, generate two-dimensional (2-D) (contour) or three-dimensional (3-D) (perspective) views of the modeled surface, determine earthwork quantities, and produce cross sections along arbitrary alignments произвольные выравнивания.

(1) Geotechnical parameters resulting from surface and subsurface explorations can be georeferenced можно привязать to a DTM resulting in a spatial пространственная data base capable of producing geologic cross sections and 2- and 3-D strata surface generation. Georeferencing spatial data requires that the information be precisely located. Global Positioning System (GPS) techniques offer a rapid and reliable way to accomplish this. Even with a GPS however, surveyed monuments and benchmarks must be identified and used as control points in the survey. (2) A GIS can be used to streamline and enhance рационализации и повышения regional or site-specific geotechnical investigations by: (a) Verifying which information is currently available and what new data must be obtained or generated to fulfill requirements for the desired level of study; (b) Sorting and combining layers of information to evaluate the commonality of critical parameters and compatibility of proposed alternatives/sites; and (c) Assigning quantitative Присвоение количественных values and relational aspects of data combinations and classifications, e.g., computing the probability of correctly assigning a given liquifaction potential for a proposed foundation construction method at a given site location. In this respect, a geotechnically augmented дополненная GIS database can be used to quantify reliability and uncertainty for specific design applications and assumptions. Burrough (1986), ESRI (1992), Intergraph (1993), and Kilgore, Krolak, and Mistichelli (1993) provide further discussions of GIS uses and capabilities.

b. Topographic maps. Topographic maps provide information on landforms, drainage patterns, slopes, locations of prominent (видный, выдающийся, заметный, именитый) springs and wet areas, quarries, man-made cuts (for field observation of geology), mines, roads, urban areas, and cultivated areas. Requirements for topographic mapping and related spatial data are outlined in EM 1110-1-1005. If older topographic maps are available, especially in mining regions, abandoned shafts заброшенных штолен, filled surface pits (ямы, шурфы, котлованы), and other features can be located by comparison with later maps. Many topographic maps are available in digital format for computer analysis and manipulation. Image files of an entire (полнота) 7-1/2 min (1:24,000) topographic map, for example, can be purchased можно приобрести. Digital elevation maps (DEM) provide a regular grid of elevation points that allow the user to reproduce the topography in a variety of display formats.

(1) Optimum use of topographic maps involves the examination of large- and small-scale maps. Certain features, such as large geologic structures, may be apparent on small-scale maps only. Conversely [ˈkɔnvɜːslɪ] наоборот, напротив

(versa, on the contrary), the interpretation of active geomorphic processes will require accurate, large-scale maps with a small-contour interval. As a general rule, the interpretation of topographic maps should proceed from small-scale (large-area) maps through intermediate-scale maps to large-scale (small-area) maps as the geologic investigation proceeds from the general to the specific.

(2) Certain engineering geology information can be inferred from topographic maps by proper interpretation of landforms and drainage patterns. Определенную техническую информацию геологии может быть выведено из топографических карт по правильной интерпретации рельефа и моделей дренажа.

Topography tends to reflect the geologic structure, composition of the underlying rocks, and the geomorphic processes acting on them. Рельеф, как правило, отражает геологическое строение, состав подстилающих горных пород и геоморфологических процессов, воздействуя на них.

The specific type of geomorphic processes and the length of time they have been acting on the particular geologic structure and rock type will control the degree to which these geologic features are evident on the topographic maps.

Определенный тип геоморфологические процессы и продолжительность времени они действовали на особенности геологического строения и типа пород будет контролировать, в какой степени эти геологические особенности проявляются на топографических картах.

Geologic features are not equally apparent on all topographic maps, and considerable skill and effort are required to arrive at accurate geologic interpretations.

Геологические особенности не столь очевидны на всех топографических картах, а также значительных навыков и усилий требуется для того, чтобы приехать на точной геологической интерпретации.

Analysis of aerial photographs in combination with large-scale topographic maps is an effective means to interpret the geology and geomorphology of a site. Information of geotechnical significance that may be obtained or inferred from aerial photographs and topographic maps includes physiography, general soil and rock types, rock structure, and geomorphic history.

Анализ аэрофотоснимков в сочетании с топографических карт крупного масштаба является эффективным средством для интерпретации геологии и геоморфологии участка. Информация геотехнических значения, которые могут быть получены или выведены из аэрофотоснимков и топографических карт включает физиография, общее почвы и горных пород, структура горных пород, и история геоморфологии

c. Geologic maps. Surficial and “bedrock” geologic maps can be used to develop formation descriptions, formation contacts, gross structure, fault locations, and approximate depths to rock. Maps of 1:250,000 scale or smaller are suitable for the development of regional geology because they can be used with remote sensing imagery of similar scale to refine regional geology and soils studies. Large-scale geologic maps (1:24,000) are available for some areas. State geologic surveys, local universities, and geotechnical and environmental firms may be able to provide detailed geologic maps of an area. Large-scale geologic maps provide information such as local faults, orientations of joints, detailed lithologic descriptions, and details on depth to rock.

Поверхностные и “основой” геологические карты могут быть использованы для разработки описаний формаций, контакты, образование, грубые структуры, места неисправности и приблизительную глубину до скальных пород. Карты Масштаб 1:250,000 или меньше подходят для развития региональной геологии, поскольку их можно использовать с изображений дистанционного зондирования подобного масштаба для уточнения региональной геологии и исследований почв. Крупномасштабные геологические карты (1:24,000) доступна для некоторых областей. Государственные геологические службы, местные университеты, и инженерно-геологические и экологические фирмы могут представить подробную геологическую карты местности. Крупномасштабные геологические карты содержат такую информацию, как локальные разломы, ориентация трещины (отдельность, (примыкания, разломов, шарниры), подробное описание литологических и детали на глубину до камня.

d. Mineral resource maps. Mineral resource maps produced by the state geological services are important sources of geologic information. For example, the State coal resources evaluation program includes preparation of geologic maps (7.5-min quadrangle areas) to delineate the quantity, quality, and extent of coal on Federal lands. The USGS and state geologic service maps provide information on oil and gas lease areas and metallic mineral resource areas. Mineral resource maps also include information on natural construction materials such as quarries and sand and gravel deposits. These maps can be used in estimating the effects of proposed projects on mineral resources (such as access for future recovery, or reduction in project costs by recovery during construction).

e. Hydrologic and hydrogeologic maps. Maps showing hydrologic and hydrogeologic information provide a valuable source of data on surface drainage, well locations, ground water quality, ground water level contours, seepage patterns, and aquifer locations and characteristics. The state geologic surveys, local universities, and geotechnical and environmental firms may provide this information.

f. Seismic maps. code of rules (OCP - 1997) Ulomov show the distribution of seismic source areas for the Russia and potential magnitude of earthquakes associated with each zone. Maps showing the timing and location of >4.5 magnitude earthquakes in Russia Карты сейсмического районирования ОСР-2016 в масштабе 1: 8 000 000 Год издания: 2016 Автор: Уломов В.И., Богданов М.И. (сост.)

Комплект карт ОСР-2016 (A, B, C, D) для территории Российской Федерации является нормативным документом, позволяющим оценивать степень сейсмической опасности в средних грунтовых условиях для объектов разных сроков службы и категорий ответственности, на трех уровнях, отражающих расчетную интенсивность I сейсмических сотрясений в баллах шкалы MSK-64, ожидаемую на данной площади с заданной вероятностью P (%) в течение определенного интервала времени t:
Карта ОСР-2016-А соответствует 10%-ной вероятности превышения расчетной интенсивности в течение 50 лет или среднему периоду Т повторяемости сотрясений один раз в 500 лет;
Карта ОСР-2016-В соответствует 5%-ной вероятности превышения расчетной интенсивности в течение 50 лет или среднему периоду Т повторяемости сотрясений один раз в 1000 лет;
Карта ОСР-2016-С соответствует 1%-ной вероятности превышения расчетной интенсивности в течение 50 лет или среднему периоду Т повторяемости сотрясений один раз в 5000 лет;
Карта ОСР-2016-D соответствует 0.5%-ной вероятности превышения расчетной интенсивности в течение 50 лет или среднему периоду Т повторяемости сотрясений один раз в 10000 лет.

 

https://www.youtube.com/watch?v=gISEdPNVme8 – Документальный фильм Джасура Исхакова о Ташкентском землетрясении 1966 г. – 1 час

 

 

(1) The Applied Technology Council (1978) published a seismic coefficient map for the United States for both velocity-based and acceleration-based coefficients. Seismic coefficients are dimensionless units that are the ratio between the acceleration associated with a particular frequency of ground motion and the response in a structure with the acceleration of the ground (Krinitzsky 1995). For the same ground motion frequency, seismic coefficients systematically vary for different types of structures (e.g., dams, embankments, buildings). These coefficients include a judgmental factor, representing experience on the part of structural engineers.

(2) Spectral Acceleration (%g) Maps for various periods of ground motion are being generated to assess seismic hazard potential. The Building Seismic Safety Council will publish updated seismic hazard potential maps in 1997 that will be in the form of spectral values for periods of 0.3 and 1.0 sec (E. L. Krinitzsky, personal communication 1996).

g. Engineering geology maps. An engineering geology map for the conterminous United States has been published by Radbruch-Hall, Edwards, and Batson (1987). Regional engineering geology maps are also available. More detailed maps may be available from state geologic surveys. Trofimov VT, Krasilova NS (2007) describes the principles of engineering geologic mapping.

 

Remote Sensing Methods

Conventional aerial photographs and various types of imagery can be used effectively for large-scale regional interpretation of geologic structure, analyses of regional lineaments, drainage patterns, rock types, soil characteristics, erosion features, and availability of construction materials (Rasher and Weaver 1990, Gupta 1991). Geologic hazards, such as faults, fracture patterns, subsidence, and sink holes or slump topography, can also be recognized from air photo and imagery interpretation, especially from stereoscopic examinations of photo pairs. Technology for viewing stereoscopic projections on the PC is available. Detailed topographic maps can be generated from aerial photography that have sufficient surveyed ground control points. Remote sensing images that are in digital format can be processed to enhance geologic features (Gupta 1991). Although it is normally of limited value to site-specific studies, satellite imagery generated by Landsat, Sky Lab, the Space Shuttle, and the French Satellite Pour l’Observation de la Terre (SPOT) satellites are useful for regional studies. Remote sensing methods listed below can be used to identify and evaluate topographic, bathymetric, and subsurface features:

a. Topographic/surface methods.

(1) Airborne photography (mounted on helicopter or conventional aircraft).

(2) Airborne spectral scanner (mounted on helicopter or conventional aircraft).

(3) Photogrammetry (for imagery processing or mapping of airborne/satellite spectral scanned data).

(4) Satellite spectral scanner (e.g., Landsat).

(5) Satellite synthetic aperture radar (SAR).

(6) Side-looking airborne radar (SLAR).