基于磁处理法的隧道永磁体排水管防结晶试验

为预防隧道排水管结晶堵塞，提出永磁体排水管关键技术指标，通过自制的永磁体排水管开展室内试验和现场试验，研究磁场强度、流量、磁体布置间距对永磁体排水管内结晶的影响，根据不同条件下结晶物的质量变化和SEM图像进行试验分析。结果表明： 1）磁场强度为0.1~0.3 T时永磁体排水管具有较好的防结晶效果，磁场强度超过0.2 T后防结晶效果逐渐降低，当磁场强度为0.4 T时永磁体排水管内结晶量反而大于普通排水管； 2）随着试验管段内溶液流量增大，永磁体排水管的防结晶效果增强，但当流量超过450 mL/s之后，防结晶效果不再随流量增大而增强； 3）经永磁体处理后，管道内的结晶物由规则的立方体形状转变为粗糙松散的不规则体，由硬质块状转变为粉末状，有从方解石向文石、球霞石转化的趋势； 4）随着管道永磁体布置间距减小，管道内最终结晶量呈下降趋势，在10、40、70 cm 3种永磁体布置间距中，最佳布置间距为40 cm。

Anticrystallization Test of a Permanent Magnet Drainage Pipe in Tunnel Based on Magnetic Treatment Method

To prevent a tunnel drainage pipe from crystal clogging, the primary technical indices of a permanent magnet drainage pipe are proposed. Then, an indoor and field test is conducted on a self made permanent magnet drainage pipe to examine the influence of magnetic field intensity, flow rate, and magnet spacing on the crystallization of a permanent magnet drainage pipe. Finally, experimental analysis is conducted according to the mass variation of crystals under various conditions and using scanning electron microscopic images. The results demonstrate the following: (1) When the magnetic field intensity ranges from 0.1 to 0.3 T, the permanent magnet drainage pipe has a good anticrystallization effect. When the magnetic field intensity exceeds 0.2 T, the anticrystallization effect gradually decreases. When the magnetic field intensity exceeds 0.4 T, the crystallization effect on the permanent magnet drainage pipe is greater than that in an ordinary drainage pipe. (2) With increasing solution flow rate in the test pipe section, the anticrystallization effect of the permanent magnet drainage pipe will be enhanced. When the flow rate exceeds 450 mL/s, the anticrystallization effect will not be enhanced with an increasing flow rate. (3) After the permanent magnetic treatment, the crystallites in the pipeline change from regular cube shaped objects to rough and loose irregular objects, and subsequently, from hard blocks to powder, with a tendency to transform from calcite to aragonite and bulgonepheline. (4) As the placement spacing of permanent magnets decreases, the final crystallization amount in the pipeline shows a downward trend. Among placement spacings of 10, 40, and 70 cm for permanent magnets, 40 cm is the optimal placement spacing.