Experimental Study On Micro-characteristic Of Rock Blasting Damnification

With the rapid development of national economic construction, rockma ss blasting technique has been widely used i n ma ny fie lds li kepetroleum, transportation, hydraulic and hydropower, mi ning and militarya ffairs which have brought e nor mo us ec onomic a nd s ocial bene fits.However, the deve lopme nt of modern blasting tec hni que ma kes blasti ngprogramme strict er. Many more r esear chers attach greater i mportance t ohow t o c o ntrol t he locati on a nd directi on of t he crack in blasting, how tocontr ol t he lengt h of t he crack, and how t o control fracture sur faceprecisely. Fragmentation eff ect includes micr ocos mic and macr oscopicparts wit hin t he blast load. The fea ture of fracture da mage not onl yconcerns wit h the char act eristic of blast l oad, but also wi th themicrostructure parameter of rock ma ss. So, i t i s s i g n i f icant to make aresearch on t he char acteristic and mechanism of r ock mass da mage fr acturefr o m t he mic r oc os mic a spe c t. Wi t h s u c h rationale, this thesis di d a n i ndoorrock blasting fract ure exper i me nt and mi cros copic te s t of s ecti ons o ngranit e te st bl oc k, and the re search fi ndings are as follows:Firstly, this thesis is concerned with a blasting experiment and itsnumeri cal analysi s. Firstl y, it got related intensity coeffi cients through thephysical me cha nic s test of gra nite test bl oc k; a nd it summari zed t h emacroscopic feat ure of bl a sting fra cture by blasti ng expe ri ment. Thefra c t ur e a r oun d t he bla st h o l e i s t he mo st apparently and then becomelower and lower al ong t he dia meter. The t est bloc k is divided i nto fourparts by the fiss ur es i n the middle of each border, but t he c or ne r s a r eal most complete. Secondly, this thesis anal yses the r ule of effecti ve stre ss displ aye d inthe nephogram and rule of characteristi c effective ele me nt str e ss wit hi n t heANSYS/LS-DYNA numerical value which simulate a granite blasting test.Come t o t he conclusion: th e wal l a r ou nd t he bl a st hole i s a ff e c t e d b y t h estress wa ve grea tly and gra d ually decr eases fr om the i nsi de t o the outsi de.And lines in the middle are greatly affected but t he four corners are hardl ybeen i mp acted; the bla sting exper i me nt is the result of e ffect s of stre sswa ve and blasti ng gas. It c an be found that those test results are consistentwith the s tress wave pr opa ga tion la w, i ndicating that it is the stress waverather than the blasting gas plays a l e ading r ol e in t he blasti ng fractureproce ss of granit e or other hard rock. Then, stress wave propagat i on la wprov ides evidences for microscopic test of secti o ns when do themicr oscopic obser vation comp arison.Final ly, on the ba si s of t he bl astin g experi ment, t he a uthor has ma de aresearch on t he r ock secti on and done a micr oscopic test on broken se ctions.Furt her more, the author has studi ed on the fract ure dama ge mechanism an drule of blasting fracture medium pr operties fr om the mi cr ocos mic aspect.Then by t he compar ison of mi crocosmic i ma ge of bloc k se ct ion i n di ff erentparts it can be summari zed t hat: Blast ing l oad brings about an ob vi ous hurtfor rock f racture, a nd t he da ma ge me c hani s m is various as the di ffer ence ofce ment ati on st rengt h and i nt ensit y of crystal particles. Usuall y, da ma gesstart fr om the part of inferior structure then ext end to th e crac k or fis sur ewhi ch wit h a hig he r i nt en si t y, t he y a re te nd t o for m a s uperi or cr ack orma croscopic fissure through inferior l ocat i ons; t he o ccurr e nce a nddevel opment of cra ck or fiss ure is closely ti ed to stre ss wa ve, which i smainly reflected at the distance to the blast hole, th e near er to it t h e hi gherthe density is; it is also connected wit h pri mar y crack, the rock i s easier tofor m ne w fi ssures and crac ks with ri ch pri mar y crack. It confir ms the theor y of guidi ng of roc k defect da mage; t he concl usi on of micr osco pictest of se ctions de eply proves stre ss wa ve’s l e adi n g rol e i n t he grani t eblasti ng da mage from the mic rocos mic aspec t.