Abstract: Aiming at the problems of high pollution,high vibration hazard and uneven fragmentation of "peninsula rock
mass" in traditional explosive blasting in open-pit mines,a limestone mine in Hebei Province was taken as the engineering
background. By designing the liquid oxygen phase change expansion blasting system,optimizing the hole network parameters
and carrying out block analysis and vibration monitoring,the rock breaking law and environmental effect of the technology under
the special working conditions of the "peninsula rock mass" open-pit mine with three empty faces were systematically revealed.
The test results show that the liquid oxygen blasting drives the tensile failure of rock mass through quasi-static expansion
pressure,forming a uniform block distribution dominated by medium blocks with a diameter of 0. 3-1. 0 m. The block rate
is significantly lower than that of traditional blasting and does not require secondary crushing. The peak value of vibration velocity
is lower than 1. 7 cm/ s. The vertical vibration energy is regularly distributed due to the difference of rock mass structure.
The horizontal vibration attenuates rapidly with the increase of distance,which verifies its low disturbance characteristics to the
slope and surrounding environment. The technical system has the advantages of environmental protection without flying stone
and dust emission reduction,which meets the needs of green mine construction. The research results provide a reproducible
technical paradigm for open-pit blasting under complex geological conditions,and have guiding significance for promoting the
engineering application of non-explosive rock breaking technology.

Key words: liquid oxygen phase change blasting,open-pit mine,fragmentation analysis,vibration monitoring,green blasting