BLASTING, Volume. 41, Issue 2, 51(2024)
Design and Practice of Rock Plug Blasting in Cryogenic Environment
The Yinsong Water Diversion Project is a largescale water diversion project aimed at solving the urban water supply problem in the central region of Jilin Province.The rock plug blasting at the intake is a key control engineering aspect of the project.The rock plug has a trumpetshaped opening with a top width of 28.4 m,bottom width of 7.0 m,and thickness of 15.76 m.The construction site is located in a cold zone with temperatures ranging from -10℃ to -15℃ during the freezing period,resulting in an ice cover thickness of approximately 0.5 m.There are limited reference cases for implementing rock plug blasting operations under such lowtemperature frozen conditions.To address the technical challenges faced,both 1∶1 scale rock plug blasting tests and lowtemperature tests on explosive materials were conducted.The results of the 1∶1 scale rock plug blasting test were consistent with the original design,as confirmed through postblast inspections which showed that the shape and dimensions of the intake met design requirements and achieved expected goals.This verified the feasibility of groove excavation hole layout,charge structure,amount of explosives used,and initiation network as planned in the design.The lowtemperature test on explosive materials resolved issues related to phase separation and loss of sensitizing bubbles for ordinary emulsion explosives under lowtemperature frozen environments.It also examined reliability by using physically treated solid particles for sensitized highwaterresistant emulsion explosives; experimental measurements met technical requirements.All communication,timing synchronization,and networking functions for highprecision digital electronic detonators operated normally.The highenergy detonation of the explosive charge was effectively controlled by implementing protective measures such as setting end caps and using epoxy resin.The sensitivity to detonation did not show any significant changes.Through a comparison with conventional blasting holes,it was observed that the equipment subjected to lowtemperature testing met the design requirements satisfactorily.Based on the results of these two experiments,optimization of the blasting scheme was carried out.During actual operations,issues such as protruding ice formations on the inner walls of boreholes and difficulties in loading explosive charges were successfully resolved.The initiation network employed three main lines encircling the lining connection section,each distinguished by a different color.Electronic detonators were grouped according to their corresponding colorcoded main line connections.This circular arrangement of blast initiation lines effectively prevented water leakage at low temperatures,ensuring waterproof integrity within connecting components and facilitating subsequent drilling and charging operations.To alleviate pressure buildup after blasting,relief holes were excavated in the upper ice layer above rock plugs for pressure release purposes.The resulting crosssection after blasting closely matched the design specifications without any noticeable collapse at tunnel entrances or excessive vibration levels at critical monitoring points during blasting operations.This study demonstrates that effective control over blast vibrations and environmental protection can be achieved through wellexecuted rock plug blasting techniques.
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CHI Xiang, YAO Chun-yu. Design and Practice of Rock Plug Blasting in Cryogenic Environment[J]. BLASTING, 2024, 41(2): 51
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Received: Mar. 1, 2023
Accepted: --
Published Online: Aug. 29, 2024
The Author Email: Xiang CHI (653085512@qq.com)