The preliminary research result of electromagnetic prospecting with the near field(transition region) of infinite-length line source in frequency domain is presented in this paper.
本文对频率域无限长线源近区（过渡区）测深的理论基础进行了探索性研究。
According to the law of geologic work, feasibility study may be divided into detailed prospecting feasibility study, preliminary exploring feasibility study and detailed exploring feasibility study.
根据地质工作的规律，可行性研究可划分为详查可行性研究、初勘可行性研究和详勘可行性研究。
Firstly, based on the preliminary evaluation for environment of dangerous source at the prospecting stage, the risk factors effect and construction of risk reduction can be determinated.
首先，据勘察资料对隧道突涌水的孕险环境进行初步评价，以确定隧道不同区段降低致险因子影响度的施工对策；
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