1 Â G Â
   The blasting project is an isolated mountain with large fluctuations in terrain, belonging to the southeastern edge of the low hills of western Liaoning, and southeast of Liaodong Bay. The bedrock in the blasting excavation area is generally exposed directly, and the cover layer is thin. The lithology is mainly composed of andesite , which is moderately weathered. In this project, the mountain is blasted and excavated to the designated landfill around the mountain.
2 Â Main engineering quantity
   The main contents of the project are the cleaning and outbound transportation of earthwork and vegetation in the excavation area, the blasting and excavation of the mountain body, the blasting excavation of the foundation pit and the excavation and construction. The total amount of the project earthwork 9.96 million m, where dredging topsoil 500,000 m. The blasting stone is 9.46 million m . And more rock blasting particle size, grading requirements and demand vary, wherein the maximum particle diameter of ≤ 10cm, quantities 120,000 m; maximum particle diameter of ≤ 25 cm, quantities 230,000 m. The maximum particle size is ≤ 40 cm , the engineering volume is 1.28 million m , the uneven coefficient Cu>5 , the curvature coefficient Cc=1 ～ 3 ; the maximum particle size ≤ 80 12133 , the engineering volume is 6.74 million m , and the uneven coefficient Cu >10 ; The diameter specification does not require a project quantity of 1.08 million m . The following specification stones refer to stone materials with particle sizes less than 40 cm and 80 cm . The rest of the stone materials for blasting mining are described in detail and will not be described in detail here.
3 Â Â Key points and difficulties
   There are many characteristics of this project that are different from previous projects. They are both the difficulty of this project and the focus of this project.
   1) The amount of engineering is large, and the amount of excavation of stone blasting reaches 9.46 million m ;
   2) The construction period is tight and the construction preparation time is tight. The owner's preparation time is only 8 days ( including the 2009 Spring Festival ) , 9.46 million m . Blasting to be completed within five months, the average monthly stonework completed digging shipped 1.89 million m, the average amount of stonework complete blasting Transportation 63,000 m per day. , A day to reach the peak of 100,000 m, tight deadlines;
   3) There are many personnel and equipment, and the coordination is large. This blasting construction site staff of 500 people, 70 to 80 digging machines, drilling rig 25, more than 300 vehicles. The blasting area and the reclamation area have a wide range of access, many construction units, many types and quantity of mechanical equipment, interpenetrating and mutual interference, frequent blasting construction in the construction area, difficulty in blasting, time-consuming, and many safety hazards. The construction site is close to the villagers, and the blasting construction is often blocked by nearby villagers. Blasting and excavation are subject to many external constraints, blasting and digging are not uniform, and the distribution of excavation and transportation is unbalanced. It is often limited by the cycle of filling and the fluctuation of transportation engineering. Therefore, there are many coordination interfaces, and poor coordination will affect the overall progress of the project;
   4) There are many specifications for stone materials, and the stone sizes used in the packing area have strict requirements. There are different requirements for the maximum particle size of less than 10cm , 25cm , 40cm and 80cm , and the unevenness coefficient and curvature coefficient have corresponding strict requirements, and the rock blasting technology requirements are very high;
   5) the bottom plate processing area, the processing area of 700,000 m. The bottom plate control requirements are high. The bottom plate treatment allows the flatness to be 0 to -20 cm of the design elevation , and the part exceeding -20 cm is backfilled to the design elevation according to the construction drawing design, and undercut is not allowed. Moreover, the floor elevation control is not on the same level, there are both vertical and horizontal slopes, and the floor of the channel area is lower than the floor of the lawn area by 80 cm . Finally , the foundation pits with a depth of 5 cm , a width of 60 m and a length of 70 m need to be blasted separately. deal with. The treatment of the floor plate greatly affects the progress of the stone step blasting;
   6) There are many construction processes, each process is supervised and reviewed, and the approval procedures are complicated. Blasting construction procedures include topsoil stripping, stripping acceptance, cleaning of shots, blasting engineer holes, measurement engineer blasthole measurement, hole depth calculation, drill hole drilling, blasthole acceptance, blasting construction design and review ( explosive and detonator usage calculation) Priming design), blasting construction design and supervision to be approved by the owner, according to the design parameters blasting charge, on-line, notify the on-site supervision and supervision, charge, within the time-line post-blasting is completed, in a defined work area Be a good guard, in accordance with the established warning signal and detonation procedures, detonation, blasting effect inspection, de-alerting, digging, square calculation, and floor inspection after the blasting command is issued. The owner and the supervisor not only require the blasting result, but also the blasthole parameters of each gun are required to operate strictly according to the design.
4 Â Main technical measures
    The project has a large amount of engineering, tight construction period, strict construction procedures and strict requirements. For the characteristics of this project, we should start from the overall situation, mainly to improve road layout, step division, blasting quality control, node construction period, blasting safety, and floor treatment. Great work. In order to achieve the final quality and schedule requirements, the following main technical measures were taken during the construction process.
  1) Read through the construction drawings to find out the excavation boundary and the floor elevation, especially the floor elevation, which runs through the entire construction process. In the initial stage, it is related to the planning of the main transportation road, the division of the steps and the selection of the height of the steps. The choice of the step height and the control of the bottom plate.
   2) Dividing the steps, mainly the selection of the step height, the selection principle: the height of each step is controlled at about 15m , and the height of the last step is controlled within 10m . The fewer the number of steps, the better, to minimize road maintenance and transportation distance.
3) Exploiting the working surface: except for the bottom layer, the working surface of each floor starts to be lower than the step floor to control the elevation of 1 to 2 m , so that in the future advancement, the bottom plate is pushed from low to high without the threshold When the working surface is opened, the first shot needs to be slanted, as shown in Figure 1. Otherwise, the first shot often has a sill on the side of the free surface, which is not conducive to the operation of the transport vehicle, reducing the efficiency of the dredging and also the loss of the vehicle. serious.
Figure 1 step opening processing diagram
Fig.1 Method of bench open
4) Transportation road planning: including major transport trunks and urinary roads. The main roads for transportation are mainly for discharging, the quality of the trunk roads is good, and the transportation distance should be reasonably optimized to the shortest. It is necessary to ensure that the main road is no more than 200 to 300 m from each excavation surface . The blasting mountain is an isolated mountain head. The three main roads around the mountain are located on the elevation of the floor of the three steps, and several trunk roads are connected between the three loops. The road plan is shown in Figure 2 . The main road is 12 to 15 m wide and has a high construction cost. Therefore, it cannot be changed at will, and it should be kept for at least 1 to 2 months. The urinals are mainly built to facilitate the access of mechanical equipment such as digging machines, drilling rigs , oil guns, and fuel trucks. The use time is short, and the construction is flexible and convenient, but it also needs to be used for 1 to 2 weeks.
Figure 2 Construction road planning plan
Fig . 2 Plan sketch of construction roading
5) Personnel allocation: The project divides the blasting area into three zones. The blasting engineers are divided into three groups, each of which is responsible for one blasting zone. The main responsibility of the blasting engineer is to be responsible for the blasthole arrangement of the blasting zone. , lifting gun treatment, pay attention to the blasting effect of this explosion area, and adjust the next blasting parameters according to the blasting effect. When the blasting work intensity is not uniform, the blasting auxiliary workers are mutually coordinated and the blasting auxiliary personnel are allocated reasonably. The measurement tasks are also cumbersome, and the content is relatively large and relatively detailed. The main work contents include the measurement of the position and depth of each hole, the measurement of the blasting quantity and the excavation quantity, the tracking of the floor elevation and the monitoring of the floor treatment. Therefore, according to the different division of labor, the measurement group is also divided into three groups, which are responsible for measuring the blasthole, stone measurement and floor treatment. Because of the relatively large area of the mountain, the team dug shipped more (up to as many as 15), the dispatcher back and forth to mobilize further away, so dispatchers by region is divided into five teams, each responsible for scheduling work in the region It mainly controls the cleaning of the guns in the area, stone excavation, large stone treatment, and floor treatment.
   6) The main technology of the specification stone production: 1 reduce the front row resistance line, create and form a good blasting air surface, avoiding the front row extrusion effect is too large, causing the explosion energy release to be blocked and causing the rock crushing and breaking. 2Adjust the unit consumption of explosives to improve the yield of stone. 3 Reduce or increase the number of single blasting rows and increase the number of blasting holes to reduce or increase the blasting collision and extrusion during blasting, and improve the yield of the specification material. 4 The charging structure adopts the uncoupled charging structure, and the uncoupling coefficient is appropriately adjusted to reduce the powder slag rate. 5 The spacer charge structure is adopted, the dosage is evenly arranged, and the crushing effect of the concentrated drug pack on the rock is reduced. 6 Using a single-row segmented chorus, the detonating network with a delay of increasing delay is used to guide the explosive energy to form a parallel thrust, causing the rock mass to tilt forward as a whole.
   7) Parameters of blasting hole network: Different hole network parameters are adopted according to the rock properties of each blasting area. The hole network parameters of each blasting area are continuously adjusted according to the blasting effect of the former blasting. The diameter of the step blasting borehole is all Ф 140 mm . According to the hole depth, the pore network parameters are mainly as follows: 3 m × 3 m , 3 m × 4 m , 3 m × 4 . 5 m , 3 m × 5 . 5 m , 3 . 5 m × 6 . 5 m , 4 m × 7 m , the local rock properties changed, and the pore network parameters were adjusted accordingly. Deep Ultra 10% by controlling the height of a step, clogging of hole depth of about 7m above 3 m, 14 m or more deep hole interval charge 1. 5 ~ 2 m , single consumption is 0 . 4 ~ 0 . 5kg/m . Control, using the initiation of detonation or V -type detonation. According to the blasting practice of the whole project, this paper summarizes the correspondence table of the pore network parameters according to the stone specification and rock explosiveness, as shown in Table 1 to Table 4 .
8) Control measures for large blocks of stone: Correct selection of the parameters of the hole network is the key to the production of the specification stone. The front cannon is not blasted well, which will affect the subsequent processes such as excavation, slag removal and drilling, and less impact for 3 to 5 days. It is 10 days and a half months, but the blasting effect is good or bad. It is also a comprehensive and complicated system engineering with the accuracy of drilling, charging and detonating network. Regardless of how accurate the placement of the mesh parameters is, it is often inevitable that there are some large blocks. If it is found that there is an oversized large block of stone, the dispatcher first prohibits the excavator from loading the large block, and then dispatches the oil gun machine to concentrate the crushing. Sometimes the blasting is just finished, and there are more large stones on the explosive pile. The oil gun machine can First break the big stone on the pile. At the beginning, the excavator did not have an intuitive concept of the size of the stone. It is often impossible to grasp the size of the stone. For this phenomenon, the standard size stone can be stacked in multiple places on the site, and the size is specified as the specification. Stone model. In the landfill area, it is sometimes found that the oversize is large. At this time, the oil cannon should be dispatched in time for timely processing.
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   9) Root control measures: Since there is no uniformity in the initial step height division, the control of the bottom plate of the 45 m platform varies greatly, and the variation range is between 40 and 45 m . The root of the platform is also relatively large and relatively large. In addition to the difference in the nature of the rock in each blast zone, the low precision of the borehole is the common cause of the root sill. Therefore, controlling the verticality of the borehole within 3 % is the key to controlling the root canal; in addition, the row-by-row initiation is changed to the V -type detonation, which can also play a role in reducing the root canal.
Table 4 Explosive 40 stone material L network parameter table
Table 4 Parameter list of hole grid for stone
Easy to blast less 40 cm
   10) Blasting mountain body penetration: This project is an isolated mountain head. It is long around the main road and has uneven distribution of stone materials. It lengthens the transportation distance of stone materials. In the process of blasting construction, it consciously accelerates the passage of narrow sections. The distance of the transportation road can be reduced in advance, the speed of discharging can be accelerated, and the blasting working surface can be increased. The project carried out 4 times of blasting work surface penetration, each time greatly speeding up the progress of blasting construction, creating favorable conditions for the completion of node engineering.
5 Â Conclusion
   During the expected construction period, the project completed the stone blasting task according to the quality of the owner according to the requirements of the owner. In particular, several node construction periods were completed on time, but it was the first time that such high strength and various specifications were encountered. The large-scale blasting project of the stone, therefore, there have been many unconsidered places in the whole construction process, resulting in the progress of the project is not very smooth, mainly the following points, for reference for similar projects.
   1) Failure to read through the construction drawings and rushing construction, resulting in unreasonable layout of the main roads, resulting in a passive situation in which the last step is too high and the bottom plate is difficult to control;
   2) The adverse effects of shallow holes on cost control are not fully estimated in advance, resulting in too many shallow holes, increasing a large part of the drilling cost, reducing the length of the blasting and increasing the unit consumption. To minimize the shallow hole, you need to try to consume the shallow hole of the step, you can plan the shallow hole of the upper step to the next step of the hole;
3) There is no inclined hole in the opening step, the step is left with the door sill, the step opening is higher than the step bottom plate, and the transportation vehicle is inconvenient to transport, which reduces the transportation efficiency;
4) The last step is too high, the average hole depth is 16 ~ 17 m , which is not conducive to the control of the bottom plate. The height of the last step should be controlled within 10 m , which can effectively control the bottom plate and reduce the workload of the secondary treatment of the bottom plate. .
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 References
[1] Â Yu Yalun. Engineering blasting theory and technology [M] . Beijing: Metallurgy Industry Press, 2007.
[2] Liu Dianzhong, Yang Shichun. Practical Manual for Engineering Blasting [M] . Beijing: Metallurgical Industry Press. 2004 .
[3] Sun Baoping, Xu Quanjun, Shan Haibo. Research on control of rock fragmentation in deep hole blasting [J] . Blasting, 2004 , 3 : 28 — 31
[4] Li Pingfeng, Liao Xinxu, Luo Guoqing. Experimental analysis of deep hole blasting parameters in large quarry [J] . Blasting, 2004, 2: 28 - 30.
[5] Cheng Yuquan. Countermeasures for improving the effect of deep hole blasting [J] . Blasting, 2002, 4: 16 - 18.
[6] Yu Zhibin, Li Jian, Gao Bo. Open Millisecond multistage deep blasthole network design optimization parameter [J]. Blasting, 2003 , 2 : 24 — 28.
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