What is a seismic piezocone penetration test?
Horizontally-oriented geophones within the penetrometer can be employed to measure the arrival times from surface-generated shear waves and provide the magnitude of downhole shear wave velocity (Vs). Seismic cone penetration systems provide rapid, repeatable, near continuous, measurements of multiple parameters that can be used to assess soil properties. To analyse earthquake hazards, an understanding of each soil behavioural parameter available from various cone penetration tests is necessary. The resultant hybrid testing contains geotechnical, hydrological, and geophysical data, termed the seismic piezocone test (SCPTu), and offers an expedient and efficient means to collect a wealth of geotechnical information with depth from a single sounding.
The measured readings from the SCPTu can be interpreted using a variety of theoretical, analytical, and statistical methods towards establishing a suite of geotechnical engineering parameters that are needed in the analysis and design of construction projects. Soil parameters are many and may include: unit weight, soil type, relative density, friction angle, dilatancy angle, pre-consolidation stress, undrained shear strength, lateral stress coefficient, elastic modulus, permeability, and other variables. In certain relationships, a single measurement may provide an estimate of a particular soil parameter, while in other cases, two or more readings may be required. Moreover, with multiple methods available, it is possible to have corroborating evaluations from two different approaches, yet also plausible to find conflicting estimates where two approaches do not agree. In the latter case, perhaps this represents the situation of a “red flag” or warning that additional testing (laboratory tests on undisturbed samples; or alternate in-situ pressure meter or flat dilatometer tests) is warranted to resolve the issue.
Horizontally-oriented geophones within the penetrometer can be employed to measure the arrival times from surface-generated shear waves and provide the magnitude of downhole shear wave velocity (Vs). Seismic cone penetration systems provide rapid, repeatable, near continuous, measurements of multiple parameters that can be used to assess soil properties. To analyse earthquake hazards, an understanding of each soil behavioural parameter available from various cone penetration tests is necessary. The resultant hybrid testing contains geotechnical, hydrological, and geophysical data, termed the seismic piezocone test (SCPTu), and offers an expedient and efficient means to collect a wealth of geotechnical information with depth from a single sounding.
The measured readings from the SCPTu can be interpreted using a variety of theoretical, analytical, and statistical methods towards establishing a suite of geotechnical engineering parameters that are needed in the analysis and design of construction projects. Soil parameters are many and may include: unit weight, soil type, relative density, friction angle, dilatancy angle, pre-consolidation stress, undrained shear strength, lateral stress coefficient, elastic modulus, permeability, and other variables. In certain relationships, a single measurement may provide an estimate of a particular soil parameter, while in other cases, two or more readings may be required. Moreover, with multiple methods available, it is possible to have corroborating evaluations from two different approaches, yet also plausible to find conflicting estimates where two approaches do not agree. In the latter case, perhaps this represents the situation of a “red flag” or warning that additional testing (laboratory tests on undisturbed samples; or alternate in-situ pressure meter or flat dilatometer tests) is warranted to resolve the issue.