At present, the roadway excavation construction can be divided into two types, namely, construction in the upper mountain and construction outside the mountain, depending on whether the personnel enter the chute or the work in the mountain. The construction in the mountain can be divided into common law construction, hanging tank construction and tank climbing construction. Class [1-4]. There is no need for personnel to go into the mountains for construction outside the mountain. It can be divided into two types: blasting construction and drilling method.

The common law, the hanging tank method and the climbing tank method are required because the personnel need to work in the mountain, the working personnel have high labor intensity, the working environment is bad, the safety is poor, the cost is high, and the efficiency is low. Drilling method generally uses a large-diameter rotary drilling rig to drill full-section in the full depth of the mountain. Although the operation is safe and the work efficiency is high, the operation cost is high, and the rock mass coefficient (f) is required to be high (generally required f< 6), so this method is difficult to promote reference in the mine. The construction of the blasting method overcomes the shortcomings of the common law, the hanging tank method and the climbing tank method. The operator does not need to enter the mountain, and has high safety. Compared with the drilling method, the utility model has the advantages of low construction cost and wide application range.

Taking the Houzhuang mining area as an example, this study uses deep hole blasting once-forming technology to carry out the construction of the well and the mountain.
1 Project Overview
Houzhuang ore is iron ore subsidiary of Shandong Gold bell of an underground mine, built in 1992, with an annual designed production capacity of 500,000 t. The Houzhuang deposit occurred in the contact zone between the limestone of the Ordovician Majiagou Formation and the Mesozoic Yanshanian diorite and skarn. It is a hydrothermal contact metaphysical skarn type magnetite with clear boundaries and occurrences. The shape is controlled by contact with the belt. The upper plate is crystalline limestone with fissure development and good stability. The Platts coefficient is 8-10. Most of the lower plate is diopside , garnet skarn and diorite with different thicknesses. The Platts coefficient is 8-10. In order to improve the construction safety and construction efficiency of the mine, the construction of the mountain, and reduce the construction cost, the construction plan of the well and the uphill mountain is studied.
2 blasting design
2.1 groove method
Deep hole blasting should be comprehensively considered when selecting the well grooving method: 1The sump form is as simple as possible; 2There is a larger groove surface area and higher blasthole utilization; 3 blast holes should be configured more Or larger holes; 4 deep hole mechanical configuration and the blasting technology level of the work team; 5 patio size and geological conditions. The large-diameter cylindrical gutter of Houzhuang Mine is shown in Figure 1.

2.2 gun hole parameters
(1) Crack hole diameter. In general, the larger the diameter of the slit hole, the better, but under the condition that the charge can be completed, the larger the pore size is selected, the smaller the pressure of the explosive on the pore wall is, and the same crushing strength is required to increase the charge. The explosive unit consumption has also increased [5-6]. The diameter of the crack hole in Houzhuang Mine is 100mm.
(2) Hole diameter. The diameter of the hole is related to the size of the cross section of the patio, the depth and the requirement of the compensation coefficient and the free surface of the slotted hole. The use of large-diameter holes facilitates the formation of the cavity and prevents the cavity from "squeezing", but the drilling time is long, the cost is high, and the performance of the drilling machine is limited. The Houzhuang Mine uses the KQJ-100D deep hole rock drill, and the selected hole diameter is 150mm.
(3) The hole spacing is determined. The arrangement of the groove of the groove should ensure that the rock in the cavity is fully broken, and that the broken rock in the cavity is prevented from "squeezing". In Fig. 2, the 1# groove has the hole wall as the free surface, and the condition is inferior to the subsequent groove hole, so the distance from the 1# groove to the hole should be small. After calculation, the distance from the 1# slot to the hole is
442mm, in this study, based on the drilling error of deep hole construction, the value is corrected to 450mm, and the final determined hole arrangement is shown in Figure 3.

2.3 blast section height
Due to the blasting caused by rock blasting, in order to ensure the blasting space required for blasting, when the patio is too high, segmental blasting is generally adopted. Increasing the segment blasting height helps to save materials and shorten the auxiliary working time, and improve the driving efficiency. However, the segment height is too high and the blasting failure occurs. To ensure a well-forming effect, it is important to choose a segment height.
The height of the section blasting is mainly related to the nature of the rock, the size of the section of the patio, and the size of the compensation space. After repeated trials, it is concluded that when the height of the patio is greater than 8m, segmental blasting is required, and the segment height should not be greater than 5m; when the patio height is less than 8m and the upper and lower ports have free faces, a blast can be performed.
2.4 Blasting sequence and crater length
In this study, the blasting operation uses viscous ammonium oil particle emulsion explosive and millisecond delay detonator blasting. The blasting sequence is shown in Figure 3, that is, the 2# hole is a segment, the 4# hole is a second segment, and the 3# hole is a three segment, 5#. The 9# hole is four segments, and the 7# and 11# holes are five segments. In the study, the pores and the bottom of the well were blocked by yellow mud, and the length of the blockage was 0.5 m (Fig. 4).

3 conclusions
(1) The section where the joint development or wet water has water will not only cause the explosive gas to escape prematurely, but also cause the dynamic pressure to be desensitized, causing the adjacent hole to smash. Therefore, the position of the well and the mountain should be selected as much as possible. Hard and dense lithology.
(2) When laying the well and going up the mountain, it is necessary to carry out smooth blasting. The top plate and the two gangs cannot be kept with umbrellas, which creates favorable conditions for deep hole construction.
(3) If perforation occurs during deep hole construction, the hole should not be blindly filled. After all the deep holes have been finished, detailed blasting scheme design is required.
(4) When designing the blasting scheme, the distribution of the deep hole at the position of the venting will change. The blasting scheme shall be adjusted according to the actual deep hole construction. The happy eye of the above blasting may become the peripheral eye in the next blasting.
(5) Before loading the drug, be sure to measure the actual depth of each hole and record it. When charging, the charging height of the orifice (upper end) is ensured to be in the same horizontal plane.
(6) During the construction process, attention should be paid to improving the precision of deep hole construction. The blasting length should be minimized during blasting to achieve the best blasting effect, achieving the purpose of reducing cost, improving efficiency and ensuring safety.

references
[1] Li Xibing, Wang Yujie, Tu Xiaoli. Rock drilling and blasting engineering [M]. Changsha: Central South University Press, 2011.
[2] Zhang Qi, Li Jiaqing. Application of deep hole blasting into wells in Zhaokou Mine [J]. Shandong Metallurgy, 2009 (4): 38-39.
[3] Liu Hongqiang. A well blasting technology and construction technology research [D]. Qingdao: Shandong University of Science and Technology, 2012.
[4] Wang Chengsheng. Well Longhole Blasting Blasting Technology at Dongguashan copper mine [J]. Mining Technology, 2010 (6): 82-84.
[5] Deng Tao, Chi Enan, Zhang Xiuyu. Accident tree analysis of open-air deep hole blasting blind cannon [J]. Modern Mining, 2015 (12): 144-145.
[6] Xue Hui, Zhou Keping, Wang Wenfeng, et al. Research on one-time blasting technology of Meishan iron mine chute [J]. Mining Engineering, 2011 (3): 50-52.
Article source: "Modern Mining", 2017.3
Author: Gang Kou, Wu Huiming, stone advanced; Shandong Jinling Mining Co., Ltd. Copyright:

1     The electrical system used by the machine has reliable control performance and strong anti-interference ability.