Description
Masw Refraction Reflection Seismograph Borehole Seismic Survey Instrument 24channels Seismometer Engineering Seismograph With Seismic GeophoneMASW is an acronym of Multichannel Analysis of Surface Waves. It is a seismic exploration technique. It evaluates ground stiffness by measuring shear-wave velocity (Vs) of subsurface in 1-D, 2-D, and 3-D for various types of geotechnical engineering projects in the most common depth range of 0-30 meters.
MASW first measures seismic surface waves generated from various types of seismic sources-such as sledge hammer-analyzes the propagation velocities of those surface waves, and then finally deduces shear-wave velocity (Vs) variations below the surveyed area that is most responsible for the analyzed propagation velocity pattern of surface waves. Shear-wave velocity (Vs) is one of the elastic constants and closely related to Young's and shear moduli. Under most circumstances, Vs is a direct indicator of the ground strength (stiffness) and therefore commonly used to derive load-bearing capacity.
Overall procedure to produce a typical 2D S-velocity (Vs) cross section consists of collecting multichannel seismic records at multiple locations as illustrated below. Each record then generates a 1-D (depth) velocity (Vs) profile, multiple of which will construct the final 2D cross section.
| Channel number 24 |
| Sample stations 1024, 2048, 4096, 8192, 16384 |
| Sample frequency |
| a, Generally, 10μs, 25μs, 50μs, 100μs, 200μs, 500μs, 1ms, 2ms, 5ms, 10ms,20ms |
| b, For micro-tremor survey, 1ms ~ 200ms selectable |
| A/D converter 24 bit |
| Signal stack and amplification 32 bit |
| Dynamic range 140dB |
| Frequency bandwidth 0.1Hz ~ 4000Hz |
| Noises 1μV(full-frequency state) |
| Amplitude consistency ±0.2% |
| Phase consistency ±0.01ms |
| Time lapse 0~9999ms |
| Date format SEG-2 |
| Working temperature 0ºC~50ºC, 90%RH |
| Storage temperature -20ºC ~ +60ºC |
In shallow seismic exploration, the commonly used methods are refracted wave exploration method, reflected wave exploration method and surface wave exploration method. The refracted wave exploration method is a long-term and mature method. It uses a large seismic source, can quickly cover a long distance to detect near-surface targets, and can characterize uplift structures with obvious velocity contrasts. It has the advantages of simple operation and high work efficiency. , the first arrival wave is easy to identify, easy to explain and other advantages, these are incomparable to the reflected wave method.
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