GEOPHYSICS FOR TRENCHLESS PROJECTS
The use of Geophysics in Trenchless projects has been maturing over the past few years. Major construction projects often use geophysics to image the sub-surface along the proposed route to detect changes in soil and rock stratigraphy, locate buried utilities and map fracture zones. The ability of geophysics to mitigate risks associated with unexpected delays has often resulted in significant cost savings. A variety of geophysical complementary methods are employed on projects of this nature. More...
Benefits and Limitations of Geophysics
Geophysical investigation is an indirect approach for investigation subsurface or structures. Various physical properties of subsurface like conductivity, hardness, presence of anomalies, dielectric properties, moisture content, density, interfaces etc., can be determined using various techniques like seismic refraction, seismic reflection, electrical imaging, ground penetrating radar, EM, VLF, Borehole geophysics etc. It is even possible to determine dynamic modulus like shear modulus, bulk modulus, Poisson’s ratio etc., using geophysical techniques. Interpretation of geophysical survey data usually requires some prior knowledge of the underlying geological structure. For optimum interpretation of geophysical data it is important that adequate direct information is available, which can be provided by boreholes or trial pits for example. More...
Geophysical Techniques
There are various techniques of geophysics which can be applied depending primarily in anticipated contrast in physical properties of the material being investigated. Various techniques of geophysics include Ground Penetrating Radar, Seismic Refraction, Seismic Reflection, Seismic Tomography, Crosshole/ Downhole seismic, Electrical Imaging, Gravity, Magnetic, EM, VLF etc. Appropriates techniques should be chosen based on the objective of investigations and nature of anomalies and host rock. Present document discusses few of the most commonly used geophysical techniques used for Trenchless projects. More...
Geophysical Surveys for Trenchless Projects
| Geophysical Surveys for Trenchless Projects | ||||
| Method | Sensitive To... | Typical Applications | Advantages | Typical Environment |
| Seismic Refraction | More... | More... | More... | More... |
| Resistivity Imaging | More... | More... | More... | More... |
| ReMi (Refraction Micro-tremor) | More... | More... | More... | More... |
| Crosshole/ downhole/ uphole | More... | More... | More... | More... |
| Seismic Reflection | More... | More... | More... | More... |
| Ground Penetrating Radar | More... | More... | More... | More... |
* Courtesy Parsan Overseas (P) Limited