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Cai J.,University of Science and Technology Beijing | Cai J.,Guangdong Hongda Blasting Engineering Co. | Zheng B.,Guangdong Hongda Blasting Engineering Co. | Wang X.,University of Science and Technology Beijing | Li P.,Guangdong Hongda Blasting Engineering Co.
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2012

According to problems of different dimensions stones mining of many engineering requirements, on the background of the Tielu port quarry, the site investigation, engineering test, mathematical model prediction and blasting control technique are used to study efficient blasting mining techniques. Before construction, the blasting area is divided into different sizes stones in the mining region according to investigating result and blasting crater test, drawing fragmentation map of different sizes stones mining and improving the efficiency of the specifications stone mining. With Kuz-Ram mathematical model, the relation between the blasting design parameters and the percentage of different sizes block stones after blasting is established. Based on the relation, blasting fragmentation and blasting effect can be predicted by blasting parameters. Simultaneously, the blasting parameters are optimized by the prediction results. The decoupling and nonuniform charge collapse blasting to reduce the rate of ore powder is studied during construction; and the mechanism is analyzed. The collapse blasting of the decoupling and nonuniform charge structure can reduce the ore powder and cost, by comparing the blasting effects of coupling charge, the hole charge and the decoupling and nonuniform charge structure. The field application shows that these techniques can meet the engineering requirements and bring economic benefits. Source


Zhang G.,University of Science and Technology Beijing | Zhang G.,Guangdong Hongda Blasting Engineering Co. | Du Z.,Qingdao Metro Corporation | Song J.,Guangdong Hongda Blasting Engineering Co. | And 3 more authors.
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2012

Zhongshan Park Station of Qingdao subway line No.3, which is constructed by arch cover method, locates in soil-rock composite layer. The maximal excavation depth is about 27.24 m. Upper overburden is composed of quaternary and highly weathered granite, and the lower part is consisted of medium-slightly weathered granite and granite-porphyry. The thickness of partially highly weathered rock layer is large and the medium-slightly weathered rock surface is partly steep, which makes the contact surface unstable. To ensure the excavation work, the ground subsidence was monitored and analyzed at the station. Results indicate that the subsidence emerges before the tunnel working face reaches to about 20 m in front of monitoring sections when the arch cover method was adopted. With the decrease of distance between the tunnel working face and monitoring sections, the subsidence velocity continues to increase. Generally, the value of subsidence is 7-15 mm when the excavation face was going through the monitoring sections. The velocity of ground subsidence increases to the maximum until the working face passes through the monitoring sections for 5-10 m. After the working face passes through the monitoring section for more than 10 m, the subsidence velocity begins to fall. Most of observation points have the trend to be stable after the working face passes through the monitoring sections for about 20 m. Supporting should be exerted and closed as early as possible to make sure that the supporting can play a good role. In addition, there is a interrelationship between the left and right pilot tunnels. It is indicated that the appropriate distance between the left and right pilot tunnels should be 2.5 times of the diameter of pilot tunnel. According to the monitoring and analysis results, a series of control measures are put forward, which are proved to be feasible and effective by practice. Source

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