地质力学磁力模型试验磁场梯度研究

Study of Magnetic Field Gradient in Geomechanical Model Test

地质力学磁力模型试验与离心机模型试验的核心思想类似,都是通过施加外加力场来达到增加试验材料应力水平的目的.本文根据磁性颗粒的磁场力公式,指出磁场梯度为恒定值是磁性材料受力均匀的必要条件之一.根据磁滞回试验测得的磁性材料的磁化强度,推导获得了均匀力场的磁场梯度下限值.采用数值模拟方法,计算了单圆台线圈、两同向电流对接线圈、两反向电流对接线圈这3种磁场生成方案的磁场梯度,比较分析该3种磁场梯度的均匀性,研究表明单线圈磁场生成方案所产生的磁场梯度较均匀且磁场空间较大,因此选择单线圈为磁力模型试验的磁场生成方案.

Geomech field to increase the ses on the magnetic anical model test based on electromagnetic force is a method that utilizes external force stress level of the test materials as similar as the centrifugal model test. This paper focufield gradient which is a dominant factor in the magnetic force formula of the magnetic ma- terials in magnetic field, presenting the constant value requirements and the MFG lower limit which is calculated according to the magnetization measured in the hysteresis loop tests. The uniformity of the Gradient Magnetic Field, which is created by single truncated cone shape coil, two opposite truncated cone shape coils energized same direction current and two opposite truncated cone shape coils energized reverse direction current, is studied with numerical simulaion method. The research of uniformity shows that the magnetic field created by single truncated cone shape coil generates a relatively large magnetic fiele with relatively uniform gradient, so the single truncated cone shape coil is choosed as the magnetic field generated scheme in the model test.