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Welcome to pay attention and search Cable official account: [tunnel early bus] what is the problem when we meet with difficulties? As an indispensable building material, the importance of concrete in engineering construction is self-evident
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However, the tunnel engineering encountered special geological structure, and the concrete consumption was serious
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Let’s first take a look at the following situation, what should we do? The geological structure is complex, affected by the structure, the rock mass is weak and broken, the joints and fissures are developed, the stability after excavation is poor, the block falls seriously, the slump is frequent, and the deformation is large, which leads to the serious over consumption of shotcrete and secondary lining concrete in the early stage
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The average over consumption of shotcrete is as high as 199%, and the average over consumption of secondary lining concrete is 28%
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Face up to the difficulties! On the premise of ensuring the quality of the project, only by focusing on intelligence, carrying out reasonable and efficient project cost management, saving energy and reducing consumption, can we create efficiency and reputation
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Yes, this is what the project has done
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At present, the over consumption of Shotcrete in the tunnel has been reduced to about 122% and that of secondary lining concrete has been reduced to about 10%
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So, how is it done? In the face of the problems, find out the reasons: first, the surrounding rock of the tunnel is poor, the change is fast, the soft and hard parts are uneven, the excavation is difficult to control, and the sliding and falling blocks cause the concrete to exceed the square; second, the blasting control is poor, and the blasting parameters cannot be adjusted in time according to the actual situation and blasting effect of the surrounding rock; third, the control measures are not implemented in place, and the site management is improper
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Strengthen the technical training of on-site management personnel
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1
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Through the internal selection of the hole with over or under excavation and well controlled concrete consumption, conduct internal observation and exchange to improve the construction level
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2
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Invite the owner’s professional engineers with rich construction experience for training
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3
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Make full use of the opportunities of technical experts to guide and inspect the project, invite them for training, and hold the “tunnel construction technology training meeting” in the construction project
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2、 In view of the rapid change of soft surrounding rock, broken rock mass and the collapse of the face after excavation, the consolidation method and the strengthening of advance support control are mainly adopted
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Three step construction technology monitoring and measuring point layout, advance small pipe setting angle and overlapping control of soft surrounding rock advance small pipe control effect 3
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Smooth blasting of soft surrounding rock tunnel blasting technology is to determine the degree of disturbance to soft surrounding rock
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If the blasting causes overbreak, not only increase the amount of slag, further expand the loose circle of surrounding rock, easy to cause deformation of surrounding rock, affect the construction Construction progress, more serious is caused by shotcrete consumption, increase the construction cost
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Smooth blasting should be done well to give full play to the self-supporting capacity of surrounding rock, so that the surrounding rock around the tunnel will not be damaged or less damaged, and it is not easy to fall or collapse
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1
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It is necessary to firmly establish the idea that smooth blasting is adopted for all kinds of surrounding rock
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According to the characteristics of weak and broken surrounding rock, strictly control the spacing of surrounding holes, control the charge amount, and charge in sections
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2
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The “seven fixed” principle is adopted: fixed personnel, fixed position, fixed machine, fixed quantity, fixed consumption, fixed reward and punishment standard
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(1) Personnel and positioning is to arrange each excavation personnel in the fixed position of the bench, so that they can adapt to the parameters of the hole direction, hole depth and so on for a long time
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Let everyone study their own position for a long time, so as to improve the drilling accuracy and blasthole forming of the excavators
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(2) Fixed machine is that each excavation personnel uses a fixed wind gun, and is responsible for the maintenance and repair of their own wind gun
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(3) Quantitative means that each excavation personnel completes the specified number of blastholes according to the location in advance, and follows the principle that each excavation personnel completes the drilling at the same time
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(4) Timing is to specify the excavation time of each shot
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(5) In order to improve the blasting effect, charge must be carried out in strict accordance with the blasting design, and the blasting design should be adjusted according to the surrounding rock condition
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(6) The evaluation standard is mainly for the excavation and forming
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The surveyors measured the overbreak and underbreak of each hole in the previous shot when setting out the blast hole
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Assess the excavators according to the measurement results
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3
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Fill in the daily report of “hole layout parameters and overbreak and underbreak data” in time after blasting, assign special personnel to adjust the blasting parameters, and track them in place; 4
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According to the rapid change of surrounding rock, “special personnel and special hole” should be done when drilling
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In the process of drilling, the drillers judge the surrounding rock in front according to the drilling speed, and adjust the charge amount in time according to the drilling speed during the charging operation
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4、 Strictly control the quality of accelerator, strictly control the quality of accelerator, select appropriate shotcreting equipment to reduce the rebound of shotcrete
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5、 Strengthen the analysis of monitoring measurement data, strengthen the analysis of monitoring measurement data, timely adjust the reserved deformation of initial support, and control the over consumption of secondary lining concrete
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6、 According to the phased control objectives of the project, the assessment method of shotcrete (Provisional) is formulated and issued
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The data of concrete over consumption is analyzed every month
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The rewards and punishments are linked with the work area and operation team
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The rewards and punishments are increased and the advanced are commended in time
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According to the actual situation, it should be revised in time, and the excessive consumption of shotcrete should be assessed once a month, and the reward and punishment documents should be issued
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The control of concrete over consumption is not only a technical problem, but also a management problem
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Closely around a series of measures, we focus on the core and wisdom, actively explore and further strengthen the control
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At present, the control of tunnel concrete over consumption has achieved phased results, but there is still room for excavation
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In the next step, the focus will be extended to assess and motivate the front-line staff, tap the construction enthusiasm of the staff, stimulate the work potential, implement the technology and management measures of concrete over consumption control, and comprehensively improve the project efficiency! Stamp“
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