MASW is a seismic tool for determining the shear-wave velocity distribution, which can be used to determine the overburden and bedrock arrangement. It examines how surface waves disperse (usually the fundamental-mode Rayleigh waves). An array of geophones, similar to other seismic methods, is used to detect seismic waves. Surface waves for MASW can be produced using an active source such as a sledgehammer. The shear wave (Vs) profile is given in one of two formats: 1D (depth) or 2D (depth and surface distance). The results can be used to evaluate soil and rock strength (stiffness), map subsurface geology (lateral and vertical variations), map low velocity layers, determine IBC Vs100 (Vs30) site classification.
The seismic cross-hole geophysical tests provide measurements of the propagation times of longitudinal elastic waves (p waves) and shear waves (s waves) between two or more boreholes along direct trajectories at different depths.The trend along the depth of the seismic wave velocities and the elastic parameters characteristic of the material being investigated can be described by the travel times and the distance between the measurement points. When the time of arrival of the seismic waves has been determined and the distance between these two points has been determined the velocities of the compressional (vp) and transverse (vs) waves are calculated, and the transmitter and receiver boreholes are known (obtained by inclinometric survey).
The results are diagrams of velocity and depth. The poisson’s ratio, the average material density, and the dynamic elastic modules ED and GD can all be calculated from the vp and vs velocities (elastic modulus and cutting module). This form of investigation is also suitable for different transmitter and receiver configurations on site, and can therefore be processed by specific 2D scanners.This kind of investigation is also suitable for different transmitter and receiver configurations on site, and thus for tomographic results to be processed by specific 2D software.
The propagation velocities of p waves and s waves in materials crossed by a single hole are determined using the down-hole technique. The travel times that elastic pulses (p and s waves) produced at the surface near the borehole employ to reach one or more geophones in the borehole at different depths are measured in the Testing Process. Velocities are calculated as the ratio of the difference in the recorded times and the difference in the paths, related to a range of depths.
During each measurement, the receiver contains three part geophones (2 horizontals and one vertical) that are firmly clamped to the borehole wall. The seismic trigger is normally surface hammering. By obtaining two shear wave records striking the plank in opposite directions horizontally As a result, the shear wave reports. The polarity of the results has been reversed. The P-wave record is obtained by measuring the P-wave produced by striking the ground with a sledge hammer. The compression and shear wave velocities can be calculated using the P-wave and S-wave records. The interval velocity is calculated by dividing the distance between the geophone locations by the arrival times difference. Following that, it’s plotted as a function of depth. As a result, the elastic properties of the encountered layers can be measured up to the borehole’s necessary depth (30m).
Electrical Resistivity Tomography (ERT) is a sophisticated geophysics technique that uses ground surface measurements to assess the subsurface resistivity distribution. An automatic multi-electrode resistivity meter is used to collect ERT data quickly. A modeled cross-sectional (2-D) plot of resistivity (Ω•m) versus depth makes up ERT profiles. The geometry, lithology, hydrology, and/or petrology of subsurface geologic formations are accurately represented by ERT interpretations, which are confirmed by borehole data or alternative geophysical data.