Research on Electrical Resistivity Prospection for Archeology

1. 一种新型考古目标电阻率测量系统研制了一种新型考古目标电阻率测量系统，该系统由双相锁相放大器、交流恒流源、电极选择器和自动采集数据的手持式计算机组成。最大电极数为256个。该系统适用于日本的考古遗址。假设电极之间的位移在1米到几米的范围内。那么合适的找矿深度为10米以下。锁相放大器的引入降低了噪声水平，缩短了测量时间。曲面不规则性的反问题分析与补偿。2-1。开发高效的计算方法。如果地面平坦、光滑，则可以采用边界元法和图像法相结合的方法将地面从系统中剔除。在这种情况下，没有必要考虑……的边界条件，更多的是地面上很远的地方。从而缩短了计算时间，提高了计算精度。地面不平整的补偿。大安古坟位于福岛县的Kouriyama市，是一座四边形后丘的锁孔墓。尽管土丘几乎是平坦的，但在土丘顶部有许多直径约为1至2米的凹坑。结果表明，这些凹陷对视电阻率值影响较大。因此，试图消除凹坑的影响。具有半球凹度的平面上的视电阻率值可以从理论上计算出来。然后，用电阻率实测值除以计算值，很容易消除凹凸度的影响。结果表明，补偿后仍存在视电阻率低于周边的地方。事后，堀山市教育委员会的挖掘发现，就在这里有一具涂有粘土的木棺。少

1. A new type electrical resistivity prospecting system for archeological targetsWe have developed a new resistivity measuring system for archeological prospection which is composed of the dual phase lock-in amplifier, constant ac current source, electrodes selectors, and a hand held computer for automatic data acquisition. Maximum number of electrodes is 256. This system is suitable for japanese archeological sites. Displacement between electrodes is asumed to be in the range of 1 meter to several meters. Then suitable depth for prospection is less than ten meters. The lock-in amplifier is introduced to reduce noise level and measuring time.2. Inverse problems analysis and a compensation of surface irregularities.2-1. Delopment of efficient caluculation method.If ground surface is flat and smooth, ground surface can be eliminated from the system by combinning a boundary element method and a method of images. In this case, it is not necessary to take into account boudary conditions for … More very far places on the ground. Then the calculation time becomes shorter and the accuracy of calculation increases.2-1. Compensation of ground surface irreguralities.Ooyasuba-Kofun is an keyhole tomb with quadrangular rear mound, located at Kouriyama city in Fukushima prefecture. There were many concavities about one to two meters in diameters on the mound top, even though it is almost flat. It was found that these concavities deeply affected the apparent resistivity values. Thus, it was tried to eleminate effects of concavities. Apparent resistivity values on the flat surface with a hemispheric concavity can be calculated theoretically. Then, it is easy to aliminate the effect of concavity, if we devide measured resistivity values by caluculated values. It was found that there was place whose apparent resistivity was lower than that of surounding area even after compensations. Afterword, itwas found that there was a clay coated wood coffin just at this place by the excavation of the Kouriyama city's board of education. Less