Small-clear-distance up-down crossing tunnel construction method

The invention discloses a small-clear-distance up-down crossing tunnel construction method. The small-clear-distance up-down crossing tunnel construction method comprises the steps of preparing for construction, examining a tunnel structure by using a radar, researching a blasting vibration theory, simulating a numerical value of a blasting vibration effect, designing a blasting technique, performing the blasting construction, performing the circular construction and the like. An SIR-3000 geological radar and a 400MHz high-frequency shielding antenna are used for detecting a condition behind a tunnel lining, data is acquired in a continuous sectional recording way, a measurement mark is made every 5 meters, a recording length is 40ns (nanometer per millimicrosecond), and a sampling rate is 512 sample points at every time of scanning. The small-clear-distance up-down crossing tunnel construction method has the beneficial effects that a small-clear-distance crossing tunnel is built on the basis of the existing tunnel, the existing tunnel is detected by using the radar, the damage situation of the existing tunnel can be accurately detected, so that the damage on the existing tunnel is avoided when in construction, the safety of the existing tunnel is guaranteed, and the normal operation of the existing tunnel is prevented from being influenced.