A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Geologic Considerations for Setting a Geotechnical Baseline Report: Intact Rock Strength Parameters
Uniaxial compressive strength (UCS) of intact rock is a key geotechnical baseline report (GBR) parameter affecting selection of construction methods and equipment, cost and schedule, and performance parameters for rock excavations, as well as design of underground structures. Project rock laboratory test results are typically not sufficiently complete to fully characterize the strength properties of intact rock to be encountered in excavations. By considering the available laboratory test data in their geologic context and supplementing the available data with field observations, local and regional geologic information, field geophysical data, supplemental index tests, and petrographic analyses, GBR baselines and ranges can be developed that more completely reflect intact rock strength and its variability. This study reviews the geologic setting and UCS and other testing performed on igneous, sedimentary, and metamorphic rock for four tunnels in New York, New Jersey, and Maryland. It examines potential factors not normally considered in compilation of UCS test results, but which could influence selection of GBR baseline values for UCS, including weathering grade, fracture spacing, saturation level, mineralogy and mineral grain characteristics, deformational history, and microscopic-scale fabrics. It considers possible sources of sampling and testing bias and provides suggestions for compensating for those biases. Finally, it evaluates the fundamental variability of the igneous, sedimentary, and metamorphic rock series at the four tunnel locations to assess the relative uncertainty and risk inherent in each type of geologic setting.
Geologic Considerations for Setting a Geotechnical Baseline Report: Intact Rock Strength Parameters
Uniaxial compressive strength (UCS) of intact rock is a key geotechnical baseline report (GBR) parameter affecting selection of construction methods and equipment, cost and schedule, and performance parameters for rock excavations, as well as design of underground structures. Project rock laboratory test results are typically not sufficiently complete to fully characterize the strength properties of intact rock to be encountered in excavations. By considering the available laboratory test data in their geologic context and supplementing the available data with field observations, local and regional geologic information, field geophysical data, supplemental index tests, and petrographic analyses, GBR baselines and ranges can be developed that more completely reflect intact rock strength and its variability. This study reviews the geologic setting and UCS and other testing performed on igneous, sedimentary, and metamorphic rock for four tunnels in New York, New Jersey, and Maryland. It examines potential factors not normally considered in compilation of UCS test results, but which could influence selection of GBR baseline values for UCS, including weathering grade, fracture spacing, saturation level, mineralogy and mineral grain characteristics, deformational history, and microscopic-scale fabrics. It considers possible sources of sampling and testing bias and provides suggestions for compensating for those biases. Finally, it evaluates the fundamental variability of the igneous, sedimentary, and metamorphic rock series at the four tunnel locations to assess the relative uncertainty and risk inherent in each type of geologic setting.
Geologic Considerations for Setting a Geotechnical Baseline Report: Intact Rock Strength Parameters
Ciancia, Mala R. (author)
Geo-Congress 2014 ; 2014 ; Atlanta, Georgia
Geo-Congress 2014 Technical Papers ; 2273-2289
2014-02-24
Conference paper
Electronic Resource
English
Geologic Considerations for Setting a Geotechnical Baseline Report: Intact Rock Strength Parameters
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