BCE s mission is to provide our clients around the world with state-of-the-art which allow for better and faster diagnostics of the sub-

Transcription

1 Seismic CPT Hardware & Software BCE s mission is to provide our clients around the world with state-of-the-art which allow for better and faster diagnostics of the sub- seismic data acquisition and analysis systems, surface. The company provides state-of-the-arseismic engineering applications. If necessary, we will customize our products to suit the hardware and software solutions for a wide variety of requirements of our clients even better. BCE's products and services consist of Seismic Data Acquisition and Signal Conditioning Hardware Seismic Data Processing Software Applied Seismology Consulting Services Seismic Data Processing Professional Seminars This brochure provides an overview of the components required to perform seismic cone penetration testing (SCPT) successfully.

2 Seismic adapter The seismic CPT acquisition is conducted with a seismic adapter that is attached to the back of a CPT cone. In SCPT two types of sensors are typically used: velocity (i.e. geophones) and acceleration (i.e. accelerometers). For a good definition of the frequency spectrum of the recorded signal, i.e. to avoid smearing, the BCE recommends that seismic adapter is equipped with accelerometers (1 Hz - 10 khz) instead of geophones (typically Hz). The BCE uni-axial seismic adaptor uses a uni-axial, high sensitivity, miniature (2 gm), ceramic shear accelerometer with the following characteristics: Sensitivity (±10 %) 100 mv/g Measurement Range ±50 g pk Frequency Range (±5 %) 0.5 to Hz Frequency Range (±10 %) 0.3 to Hz Frequency Range (±3 db) 0.2 to Hz Resonant Frequency 35 khz Phase Response (±5 ) (at 21 C - 70 F) 2 to 6000 Hz Broadband Resolution g rms Non-Linearity 1 % Transverse Sensitivity 5 % Temperature Range (Operating) -54 to +93 C -65 to +200 F The tri-axial adapter uses a triaxial, high sensitivity, ceramic shear accelerometer, with the following characteristics: Sensitivity (±10 %) 100 mv/g Measurement Range ±50 g pk Frequency Range (±5 %) 2 to 5000 Hz Frequency Range (±10 %) 1.4 to 6500 Hz Resonant Frequency 25 khz Broadband Resolution (1) g rms Non-Linearity 1 % Transverse Sensitivity 5 % Temperature Range (Operating) -54 to +121 C -65 to +250 F Page 2

3 Signal Conditioning Boards BCE offers highly configurable seismic data acquisition systems (SDASs). These systems are based upon a Plug and Play (PnP) philosophy where systems with a large number of channels are easily assembled from uniaxial and triaxial signal conditioning boards (SCBs). The signal conditioning boards are also designed to simultaneously acquire data from passive geophone and/or high precision active accelerometer sensors depending on the job requirements. BCE's Signal Conditioning boards contain a differential pre-amplifier stage, a programmable gain amplifier, a programmable low pass filter and a trigger unit with programmable gain. BCE s signal conditioning board has the following characteristics: Power Supply Requirements 6-18V/400mA AC or DC Differential pre-amplifier specifications Noise Gain Common Mode Suppression <10ηV/ Hz 3.5dB >90dB System Gain specifications (full scale signal +/- 10V 0 84 db (adjustable in 6dB increments) Frequency range 1Hz 10 khz +/- 3dB User selectable 2nd and 4th order low pass filter anti-aliasing filters Programmable Filter Dynamically adjustable anti-aliasing filter based on 1/3 sampling frequency Trigger Adjustable trigger level. Page 3

4 SCPT Data Acquisition Software SC1-DAC and SC3-DAC are software programs that facilitate the data acquisition of uniaxial and tri-axial SCPT time series data respectively. The data can then be analyzed in more detail using the BCE seismic data analysis software. BCE s standard seismic data acquisition software packages include the following features: 1. Configurable for either geophones or accelerometers. 2. Configurable for either contact Switch or Sensor Triggers. 3. Suitable for P-Wave and S-wave. 4. Option for a time delay in collecting data. 5. Maximized data sampling rate. 6. Option for Data Stacking. Page 4

5 SCPT Data Acquisition Software The Pro series of the BCE data acquisition software allow better and faster diagnostics of the sub-surface during data acquistion. In the current release preliminary estimates of right and left side SH-wave interval velocities are generated automatically during a Seismic Cone Penetration Test (SCPT). Future releases of this software will also provide the user with automatic estimates of the absorption values (QS and QP), interval P-wave velocities, and the interval low-strain elastic constant. The Pro version of the data acquisition software includes the following features: 1. Bandpass, high pass, low pass, and notch digital filters. 2. Automatic full waveform SH-wave interval velocity estimates (SC3-DAC Pro only). 3. Displays of peak particle accelerations, velocities, and displacements. 4. VSPs with trend line estimation. 5. 3D Displays of VSP Profiles. Page 5

6 SCPT Data Acquisition Software The microseis version of the data acquisition software facilitates the autonomous data acquisition of seismic cone time series data. It utilizes passive (micro-)seismic monitoring technology where a dedicated trigger channel remotely discerns whether an event or trigger has occurred. When such an "event" or trigger is detected the SCPT seismic data is stored to file at the user specified sampling rate and time. SC1-μSeis and SC3-µSeis allow for a Contact or Sensor trigger. The Sensor trigger is based on BCE s so-called SEED (Signal Enhancement and Event Detection) algorithm, which uses real time Bayesian Recursive Estimation (BRE) digital filtering techniques to analyze in real-time the raw trigger data. The microseism version of the data acquisition software includes the following features: 1. Configurable for either geophones or accelerometers. 2. Configurable for either Contact or Sensor trigger. 3. Implementation of the SEED (Signal Enhancement and Event Detection) algorithm, which uses real time Bayesian Recursive Estimation (BRE) digital filtering techniques to analyze in real-time the raw trigger data. 4. Short term average / long term average (STA/LTA) event detection. 5. Automatic data gain setting. 6. Suitable for P-Wave and S-wave. 7. Maximized data sampling rate. 8. Ability to save trigger channel and pre-trigger data to file. 9. Functionality to convert acquired seismic data into the SC1,3-RAV data format. 10. Option for post Data Stacking. 11. Bandpass, high pass, low pass, and notch digital filters. 12. Automatic full waveform SH-wave interval velocity estimates. 13. Displays of peak particle accelerations, velocities, and displacements. 14. VSPs with trend line estimation D Displays of VSP Profiles. Page 6

7 SCPT Data Analysis Software SC1-RAV and SC3-RAV are software programs that facilitate comprehensive SCPT data reduction, analysis, and display. The user is provided with an extensive set of mathematical tools and patented algorithms to derive DST interval velocities and to quantify vertical seismic profiles. In addition, these programs allow the review of frequency spectra, the comparison of both unfiltered and digitally filtered traces, and the plotting of interval velocity profiles. The programs include the following features: Ability to process not only data obtained with BCE data acquisition systems, but also SEG2 seismic data ( while retaining important Meta Data Descriptors). Configurable for either geophones or accelerometers. Extensive frequency spectrum analysis. Bandpass, high pass, low pass, and notch digital filters. Patented P-Wave and S-wave velocity estimation algorithm. Batch job processing. Source wave arrival time estimation. Linear least squares regression interval velocity estimation. Reverse Polarity Technique. Forward Modeling Downhill Simplex Method (FMDSM) in estimating interval velocities. Display of Vertical Seismic Profiles (VSP) with trend line specification. Display of peak particle accelerations, velocities, and displacements. 3D Displays of VSPs. Calculation of interval Gmax values. The ability to carry out data interpolation to increase the time series resolution. Post data stacking. Signal decay function to minimize the effect of source wave multiples. Display of calculated interval velocities. Page 7

8 SCPT Data Analysis Software SC3-RAV, the tri-axial analysis software, also includes the following features: Polarization analysis. Ability to rotate the X, Y, and Z source wave responses onto a single full waveform axis. Ability to rotate the X, Y, and Z responses onto the P-SV-SH raypath coordinates. Seismic source wave incident angle estimation. Attenuation analysis and absorption estimation. Three independent velocity estimates for the X, Y, and Z components. Velocity estimate for the full waveform (i.e. incident wavelet, ρ = x 2 + y 2 + z 2 ). For more information about these products (incl. a copy of the user manuals for the various software packages) please visit our website ( or contact our offices: info@bcengineers.com phone: Canada: (604) USA: (903) Page 8