针对A，B，C，D四种改良型中深孔爆破，详细计算这四种改良类型的爆炸荷载时长，并与相对应的普通类型进行对比。通过非对称三角形荷载的频谱分析，发现荷载时长与频率成反比例关系。在此基础上，研究表明改良型中深孔爆破在一定程度上提高了爆破振动频率，降低了建筑物发生共振的几率，实现了增频降幅的目的。以大连市辛寨子地铁明挖车站为例，该工程项目采用浅孔和A、C改良型中深孔联合爆破技术，达到了降低造价、缩短工期的目标。

For the A, B, C, D four kinds of modified middle-deep hole blasting, detailed calculating the blasting load length of the four styles and comparing with normal middle-deep hole blasting. By spectrum analysis of asymmetric triangular load, drawing the conclusion of inverse proportional relationship between load duration and frequency. On the base of it, the study shows modified styles improve blasting vibration frequency to some extent, reduce the chance of building resonance, and achieve the goal of increasing frequency and decreasing amplitude. Take the engineering program of open-cut subway station at Xinzhaizi of Dalian city which uses joint blasting technology of combining the shallow hole with modified middle-deep hole of A and C styles for example. The program achieves the aim of reducing cost and shorting the time limit.