The Study Of Combine Nuclear Magnetic Resonance And Transient Electromagnetism Method For Interpretation

The Nuclear Magnetic Resonance(NMR) has its unique disadvantage in the fieldof detecting as an exceptional geophysics method. It achieves the aim by receiving theelectromagnetic signal when the atom core precession in the geomagnetic field,However, it is just a short time it introduced to our country, it is not be familiar withthe worker of geophysics widespread, so this paper will recommend the theory andtechnique. In the process of tunnel/colliery excavation, the inundation ahead is thecommon disaster, this paper offer the resistivity distribution ahead the face based onthe fluctuate thin plat. preparing for the inverse of water content.This paper start from the calculation of magnetic field arouse by the loop in thehomogenous half-space of frequency domain, offer the process of calculatingmagnetic field in in the homogenous half-space, layered medium at any point.in thisprocedure, we account the problem of integral of double Bessel function, because themagnetic field expression stimulate by the direct current loop is the same as the formwe need to solve, we numeration the double Bessel integral with the method ofcomputing direct current loop, solving the problem of calculation the magnetic inhomogenous half-space and layered medium, at last, having an attempt of describingthe distribution of magnetic field in the three dimension media. computing the defeatangle in the space. finished the response of one dimension, two dimension and threedimension NMR.Translation the measured signal to the geological parameter we need is theultima goal of geophysics detecting, we inversed the model when the groundwaterdistribution as one dimension, two dimension and three dimension with the algebraicplane technique with the forward modeling curve. the inverse result is in accord withthe model designed before. Combine with the lining case, inverse the signal record ina survey of groundwater in xin jiang,the result is in accordance with the NUMISsystem.The NMR can just offer the information of groundwater distribution, as to thespread of resistivity of medium, the TEM method is very perfect, it has great significance to combine the two method to know more about the underground.However, the distribution of resistivity effect the NMR at the same time. especially inthe work of tunnel prediction ahead, the distribution of resistivity ahead the face isnecessary. before the mature of TEM inverse for three dimension situation, it makesthe three dimension resistivity tomography based on fluctuate thin plat a practical skill.Design the initial model based on the resistivity, inversing the forwarding response,the result is according to the model.Both the theory and practical date prove that it is possibility to combine the twotechniques, make a prepare for the next unity explain of tunnel prediction.