矿井瞬变电磁法接收端单向屏蔽

矿井瞬变电磁法由于受到全空间效应的影响,无法实现井下的定向探测,目前尚无从根本上解决该问题的方法。对采集信号进行单向屏蔽有望从根本上突破矿井瞬变电磁法定向探测的难题。本文通过理论计算、仿真模拟对不同材料和不同结构单向屏蔽装置的电磁场响应特征进行定量分析,确定单向屏蔽装置材料及结构设计参数,并通过物理实验验证屏蔽装置的单向电磁屏蔽效果。研究表明：通过仿真模拟得到锥形结构的坡莫合金屏蔽罩相对其他结构屏蔽装置有更好的单向屏蔽效果,能够在有效压制非探测方向干扰信号的同时,突出探测方向的有效信号；在锥形屏蔽罩高度不变的情况下,锥形屏蔽罩顶角越大,单向屏蔽效果越好。此外,仿真模拟得到的屏蔽方案经物理实验证实具有明显的单向屏蔽效果。

Study on one-way magnetic shielding at the receiver of mine transient electromagnetic method

Due to the influence of the full-space effect, the mine transient electromagnetic method cannot achieve downhole directional detection. One-way shielding of collected signals is expected to fundamentally break through the problem of directional detection of mine transient electromagnetic method. This paper quantitatively analyzes the electromagnetic field response characteristics of different materials and different structures of unidirectional shielding devices through theoretical calculations and simulations, determines the material and structural design parameters of the unidirectional shielding device, and verifies the unidirectional electromagnetic shielding effect of the shielding device through model experiments. The research shows that the permalloy shielding cover with the conical structure obtained by simulation has a better unidirectional shielding effect than other structural shielding devices. It can effectively suppress the interference signal in the non-detection direction while highlighting the effective signal in the detection direction; When the height of the tapered shield is constant, the larger the top angle of the tapered shield, the better the one-way shielding effect. The shielding scheme obtained by simulation also has obvious unidirectional shielding effect after physical experiment verification.