Adverse effects on the environment during the exploitation of rock mass by blasting in a quarry

U čvrstim i vrlo čvrstim stijenama eksploatacija uglavnom počinje bušenjem minskih bušotina i miniranjem. S druge strane, miniranje je poznato po negativnim utjecajima na okoliš. Vibracije tla, razbacivanje komada stijene i zračni udar, najznačajniji su primjeri takvih utjecaja. Kod detonacije eksplozivnog punjenja oslobađa se velika količina energije. Jedan dio raspoložive energije pretvorbom prelazi u kinetičku energiju, odnosno energiju seizmičkih valova, a manji dio u energiju zračnih valova. Takvi oblici energije štetni su i mogu izazivati oštećenja na obližnjim objektima. Kako bi se radovi bušenja i miniranja koji se provode u svrhu eksploatacije tehničko-građevnog kamena odvijali bez štetnih posljedica, potrebno je prilikom svakog miniranja izvoditi kontrolna mjerenja veličina oscilacija tla i zračnog udara. Mjerenje se provodi pomoću malih prijenosnih seizmografa čije su ulazne jedinice trokomponentni geofon i mikrofon. Mikrofon mjeri tlak zračnog udarnog vala, a trokomponentni geofon mjeri veličine oscilacija tla, odnosno pomak, brzinu, ubrzanje i frekvenciju seizmičkih potresnih valova. Kako bi nepoželjni efekti miniranja ostali unutar normom propisanih granica, potrebno je pravilno projektirati parametre miniranja poput dubine i promjera minskih bušotina, duljine čepa, intervala otpucavanja među bušotinama i sl. Kroz ovaj rad bit će prikazan postupak terenskog mjerenja i analize rezultata s praktičnom primjenom na primjeru proizvodnog miniranja na kamenolomu u Ljubešćici. Na temelju rezultata mjerenja izrađen je proračun dopuštenih količina eksploziva po stupnju paljenja, s obzirom na to da se pokazalo kako je smanjenje količine eksploziva najbolji način reduciranja vibracija tla prilikom miniranja.In solid and very solid rocks, exploitation usually begins with the drilling of blast holes and blasting. On the other hand, blasting is known for its adverse effects on the environment. Ground vibrations, fly rock, and air blast are the most significant examples of such influences. The detonation of an explosive charge releases a large amount of energy. One part of the available energy is converted into kinetic energy, i.e. the energy of seismic waves, and a smaller part is converted into the energy of airwaves. Such forms of energy are harmful and can cause damage to nearby buildings. In order to avoid negative consequences of drilling and blasting works which are carried out for the purpose of exploiting a technical-building stone, it is necessary to perform control measurements of ground vibrations and air blast during each blasting. The measurement is performed by using small portable seismographs, whose input units are a three-component geophone and a microphone. The microphone measures the pressure of an air blast wave, and a three-component geophone measures ground vibrations, i.e. the velocity, displacement, acceleration, and frequency of seismic waves. To keep the undesirable effects of blasting within the limits prescribed by a norm, it is necessary to properly design the parameters of blasting such as the depth and diameter of boreholes, the stemming length, the firing interval between boreholes, etc. The thesis presents the procedure of field measurement and the analysis of results with their practical application on the example of production blasting at the quarry in Ljubešćica. Based on the measurement results, a calculation of the allowable quantities of explosive charge detonated per delay was made, since it became evident that reducing the amount of explosive charge is the best way to reduce ground vibrations during blasting