Theoretically, the change of the SRC length reflects the diversification of the vertical magnetic, so there will be obvious change on the magnetic gradient along the axial direction of the SRC.

• 理论上，钢筋笼长度的变化反映了竖向磁性物理量的变化，因此沿钢筋笼轴向的磁梯度将产生明显的变化。