| The drilling and blasting procedure was still the present main construction method of coalmine, along with the exploitation scale expansion, detonation charge of blasting construction work and the intensity of vibration also increases, the frequent blasting vibration has had influence to security of roadway wall rock and the support structures. For many years, domestic and foreign researchers had did massive research work on the direction law of blasting vibration, the harm mechanism and the control countermeasure and so on, has yielded substantial result, mainly concentrates in the ground project blasting vibration effect influence on the peripheral buildings, blasting vibration effect of tunnel (including road, railroad and hydraulic tunnel) construction to the neighboring tunnel and the wall rock influence, as well as damage caused by excavates blasting vibration effect of large-scale building foundation and underground workshop construction to the wall rock, open-air mine mining blasting vibration and so on, and research of blasting seismic effect on the roadway stability rarely. In the foundation of domestic and foreign correlation research material consults, through vibration monitor on dissimilar conditions of coal mine roadway excavation blasting and deep hole loose blasting, applies the HHT and Wavelet Packet Transform based on the Matlab software, researched questions about vibration characteristic of coal mine construction blasting, it’s influence on roadway wall and support structures and so on. Main researched work and achievements of this paper are as follows:Analysis formation, spread rule and influence factors of blasting energy distribution and blasting seismic wave by theoretically. Establish blast hole decoupling charge blasting model, pressure peak value of blasting stresswave and velocity of blasting vibration on different decouple medium and coefficient were tested and analysised, pressure peak value of blasting stresswave and velocity of blasting vibration decreased along with increasing of decouple coefficient, and both value of water-decouple charge were greater than air-decouple charge.According to the different situation of blasting construction, blasting vibration monitoring and analysis has been carried on, discovered that peak value of horizontal radial direction (roadway moves towards direction) component was the biggest of three direction components in the vibration velocity three, obtained attenuation rule of vibration resultant velocity and its components in all directions, and difference to blasting on ground.Comparative analysis of typical vibration signal by the HHT Transform and Wavelet Packet Transform respectively, obtained frequency spectrum, obtained under the different demolition condition to vibrate the signal the frequency spectrum, energy distribution characteristic of vibration signal under different conditions:master vibration frequency of soft rock roadway excavation in90-260Hz, and the main energy concentrates in160-260Hz, the vibration duration was about150ms. For short-delay blasting, the vibration instantaneous energy appears many peak values, corresponds with the particle vibration peak value, the biggest instantaneous energy was caused by detonated breakage-hole charge. Vibration velocity of deep hole loose blasting only have a peak value, master vibration frequency o in40-80Hz, the frequency of vibration velocity value bigger than1cm/s distributed in two scopes:45-60Hz and70-100Hz; and the EMD decomposition indicated that, main energy concentrates in50-100Hz, according to the relative energy value, the entire frequency range can be divided into three "sub-frequency band", and internal energy value of each frequency band experiences three stages:wave troughâ†'wave crestâ†'new wave trough.According to the roadway construction actual situation and the rock physics mechanics performance test results, two roadway computation models under the blasting dynamic load had established by FLAC3D, obtained stress and deformation characteristic of roadway wall rock and support structure of different initial ground stress, cross section size and support structure conditions under blasting dynamic load. The result indicated that, under blasting dynamic load, stress and displacement of wall rock has increases, increased range in15%～20%; stress and deformation of wall rock increases along with increases of initial ground stress and the roadway section size, reduces along with the increases of support anchor rod length, shotcrete thickness have micro influence to stress and distortion of wall rock. The wall rock plastic area size is most related with the roadway cross section and the initial ground stress, the bigger cross section, the higher ground stress, plastic area scope is bigger; the roadway arch is at the elastic condition, but before has received cutting and tension failure, the side wall is at shearing failure condition, and the floor receives cuts and stretch dual function, certain depth only receives shear action; regarding high ground stress condition, arch of wall rock mainly shear action; thickness of shotcrete affect wall rock plastic area development. The biggest deformation of shotcrete appear in the arch, distribution reduce along the roadway gradually, and the smallest deformation appear in straight wall down corner of latest excavates section; the most flexural stress appear in the latest excavates section, influenced by shearing stress SXY.Loose scope of wall rock tested by sound wave and analyzed, proved influence of blasting vibration effect on wall rock loose scope of soft rock roadway on the other hand. For the researched roadway, the wall rock loose scope in1.6-1.65m after excavates, has increased about0.2m under the blasting vibration effect, it was about10%.According to the decay laws, effect factors and influence of roadways of explosion energy and blasting seismic wave, control plan were given from two aspects of blasting energy control and surrounding rock, supporting structure in detaile. |
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