Construction method for excavation of auxiliary shaft extension project of Panlong lead-zinc mine

1 Project Overview

Lead zinc mine Auxiliary dragon wellhead elevation + 64.6m, shaft excavation cross section length × width = 3.9m × 3.4m, the thickness of the support is 250mm, the net cross section of the support of length × width = 3. 4m × 2.9m; the first phase of the wellbore was constructed to -183m at the end of 2013, the cage was operated to the middle section of -170m, and the auxiliary well extension guide was constructed to the middle section of -320m.
In 2015, in order to meet the needs of personnel, the middle section of the auxiliary shaft service was extended to the middle section of -320m, the bottom elevation was -335m, the wellbore was 152m, the wellbore support was from -170m to -335m, and the support was 165m. The support is made of reinforced concrete.
2 construction organization plan
2.1 Overall plan of construction
The auxiliary shaft extension project adopts the method of guiding well back excavation, the wellbore is digging and expanding, and the short excavation and short building method. The overall construction plan is as follows: the first stage is to use the hanging tank method to complete the well guiding construction, and the tunneling in the middle section of -220m The construction of the auxiliary shaft in the construction chamber is being excavated and hoisted, and the construction method of short excavation and short masonry is adopted - 220~-335m middle section wellbore. In the second stage, the middle section of the auxiliary shaft cage service was moved up to the middle section of -120m, the stable vehicle was installed on the surface, the installer and the material lifting winch were installed in the middle section of -170m, and the load-bearing platform (reconstructed by the sealing disc) was set in the middle section of the -220m section. Construction method of short excavation and short masonry construction - 170~-220m middle section wellbore.
2.2 Construction method
2.2.1 Hanging tank anti-well method construction guide
The guiding wells of this project are firstly drilled, and the wells are drilled according to the underground well development method. The wells in the section of 220--270m and -270～-320m are upgraded by the JD-3 swimming winch installed at the wellhead. Hua-II hanging tanks, personnel in the hanging tanks for eye-catching operations, blasting meteorites from the bottom of the well using scrapers and mining trucks for loading and transport. The blasthole arrangement, blasting parameters and expected blasting effect of the hanging tank backhole method are shown in Figure 1, Table 1 and Table 2, respectively.

The operation method of the hanging tank anti-well method is divided into two types: early and middle shifts. Under normal circumstances, one tunneling cycle can be completed per shift. The footage of each cycle is 2m (blasting utilization rate is 89%), and the footage is 4.0m per day.
2.2.2 Forward expansion of the wellbore
Since the wellbore is square, the accuracy of the wellbore position is high, and the phenomenon of “torsion angle” is not allowed. Therefore, it is advisable to use a forward expansion brush, and use an infrared laser projector to lower the wellbore control line and calibrate the section outline according to the size of the wellbore. Two YT-28 air-leg rock drills were used to simultaneously drill the eye, and the peripheral eye and the auxiliary eye were arranged along the contour of the section, and the well was used as the blasting free surface for rock drilling and blasting, and the forward brushing was carried out on the wellbore.
Also, according to the relevant provisions of "non-ferrous metals for construction of underground heading," the two dug an approach must be taken in the wellbore Enlargement process of pouring concrete supporting wall were closed and when the surrounding rock, eliminate ballast stone fall Damage to the workers. When the sneeze is used, the sprayer is arranged at the wellhead, and the suspended air supply pipe is also used as the sneeze feed pipe to temporarily sneeze the wall of the well; the thickness of the spray is 50mm, and the anchor net is sprayed. The thickness is 100mm and the smoldering soil strength rating is C20.
The project is expanding the brush to use the horizontal stable installation of the steady lifting of the wellbore and the sealing plate. The single-layer hanging plate is used as the working plate as the safety protection plate. The two-hole method is used for the construction from top to bottom. , the wellbore is expanded to the specified section size.
2.3 Auxiliary shaft lining support construction method and process
The auxiliary shaft wall is made of C25 double-layer bidirectional reinforced concrete support. In order to facilitate the arrangement and installation of the steel bars, the method of centralized support from the bottom to the top is adopted. When the concrete is poured in the -220～-320m section of the wellbore, the mixing station is arranged near the middle section of the -220m well; the agitated concrete is transported to the working face by the concrete conveying pipe suspended in the well-220m or less; when -170 When the concrete is poured into the well of ~-220m section, the mixing station is arranged in the middle section of -170m. When watering, it should be operated along the well pattern by circular layered watering to prevent the local deformation caused by the template extrusion or squeezing the template. The thickness of each layer should not exceed 300mm, and the vibrating rod should be vibrated. .
2.4 Lifting auxiliary system

Due to the small amount of auxiliary shaft excavation work and limited space for equipment arrangement in the wellbore, the lifting auxiliary system should try to select simple construction equipment with small size, convenient lowering and quick installation. Auxiliary well construction - When the wellbore is below 220m, install 3 JM-10 and 1 JM-5 winch horizontally at the middle of the -220m Matoumen and the junction, and use the upper chamber to arrange the sky wheel platform. One of the JM-5 lifts a stable hanging basket for a person and material up and down, two JM-10 lifts the stable car to hang a double-layer work plate and suspension hydraulic template, and one JM-10 stabilizes the car. A 10t hanging hoist suspends Φ159mm×3.5mm concrete conveying pipe, Φ65mm steel braided air supply pipe and Φ25 glue water supply pipe (the air supply pipe is also used as a sneezing safety support feeding pipe) to fix the bolt along the well wall The power cable and signal cable are lowered with the hanging plate. During the construction of the 170--220m section of the wellbore, the -170m horse head door does not have the conditions for expanding the brush. Therefore, a small number of small lifting and hanging facilities are arranged there, and the large facilities are suspended by two JM-10 stable vehicles on the surface. See Table 3 for installation equipment.

3 security measures
3.1 Enhancing the safety and reliability of the auxiliary system is the guarantee of construction safety
(1) It is required to design and upgrade the layout plan of the auxiliary system. If the space is insufficient, it must be properly expanded and topped to ensure sufficient construction safety distance.
(2) The two strings of the stable steel wire ropes arranged on the ground surface are not allowed to be entangled with the cage lifting wire rope and the brake rope, so as to avoid affecting the safe operation of the cage and avoiding the high-voltage cable in the wellbore.
(3) After the installation of the auxiliary equipment is completed, it is required to notify Party A to organize the relevant departments to pass the acceptance before use.
(4) Every shift of the excavation construction must check whether the auxiliary system is normal, and it is forbidden to construct if there is any problem.
3.2 Shaft construction fall prevention is the key to safety
(1) The wellhead requires the installation of a fixed or active safety barrier. The operation of the wellbore requires the safety belt to be installed to prevent the danger of the wellbore falling.
(2) Wellbore construction, steel, equipment, and other materials must be required to have special lifting containers. After being installed on the wellhead sealing plate, it is allowed to be lowered. It is forbidden to unload the lifting container or to lower the material at the horse head door without the working platform.
(3) The movable wellhead cover is required to be flexible, so that many people can use manpower to move or remove the wellhead cover on the wellhead sealing plate.
(4) Shaft construction of the wells that have been constructed, and the anti-drop net under the working platform can effectively prevent falling.
(5) In order to ensure that the -220m load-bearing platform has sufficient carrying capacity, the platform is required to be paved with pine for buffering. The forklift slags out at the edge of the -220m auxiliary well sealing plate. It is required to set up a car block at the wellhead and hang a safety warning sign. When the slag is slag, the forklift wheel is prohibited from crossing the block to enter the sealing plate.
3.3 It is the key to ensure the safety of the cross-operation of the cage operation and the auxiliary shaft extension construction.
(1) Organize and coordinate relevant departments and construction units to move the auxiliary well cage up to -120m middle section, move the cage brake rope up to -130m elevation, and remove all signal, lighting and power systems in the -170m middle section auxiliary shaft junction to avoid The influence of the extension of the auxiliary shaft on the operation of the cage.
(2) Two safety protection platforms are installed between the operation of the cage and the extension of the auxiliary shaft to ensure that the operation of the cage and the extension of the auxiliary shaft do not interfere with each other to ensure safety.
3.4 Construction quality determines the fundamentals of permanent engineering safety
(1) The requirements for wellbore excavation shall be constructed according to the standard by smooth blasting and reasonable excavation construction organization to reduce over-excavation of the borehole wall.
(2) The wellbore operation requires waterproof measures, especially the waterproof measures at the construction site of -220m to reduce the loss of sand and concrete mud to the bottom of the well, resulting in the deterioration of the quality of the masonry and increasing the difficulty of cleaning the bottom of the well.
(3) The wellbore at the construction site of -220m has no lateral support of the rock mass. It is required to thicken the well wall to 0.5m to avoid the weak point of the wellbore and ensure the safety of the wellbore.
(4) After the construction of the steel pipe in the wellbore construction, it is required to notify the supervision or the site acceptance before the concrete pouring of the wellbore, and the pouring is allowed after the confirmation is passed. Otherwise, the construction is suspended, and the pouring is required after the design is rectified and accepted.
3.5 Personnel Management
(1) Construction requirements The corresponding safety person in charge shall be designated, and the materials, equipment handling and lifting requirements shall be checked and confirmed.
(2) Party A assigns a safety officer to the construction team for safety supervision. The construction must obey the correct instructions of Party A management personnel and safety personnel on safety issues.
4 Conclusion
According to the above method, the auxiliary shaft extension project was excavated for 6 months, and the construction was completed as expected. Throughout the construction process, the construction plan, technical requirements and safety measures are in place, and good construction results are achieved. It also shows the difficulty of vertical shaft excavation and extension construction. Among them, the following points are worth learning:
(1)Using the existing middle-level level, adopting the well-drilling back-excavation first, digging and expanding the brush, using the scraper to slag at the bottom of the well, the well-drilling and the wellbore are digging and expanding, the slag is simple and fast. .
(2) The construction organization of short excavation and short masonry can effectively avoid excessive over-excavation of the wellbore, and the temporary support of sneezing can improve the safety factor of excavation construction. In addition, the short-drilling, short-drilling and excavation alternate construction organization forms a comprehensive professional construction team integrating the wellbore excavation, exiting, steel installation, vertical mould and concrete pouring, and the construction efficiency is greatly improved.
(3) The wellbore with high measurement accuracy or need to be built is not suitable for square wellbore. The utilization of square wellbore is large, but it is not conducive to construction precision control. The utilization of circular wellbore section is small, but it is easy to control measurement accuracy and easy to construct.
(4) In order to ensure the impact on the operation of the auxiliary well cage, it is necessary to use the independent lifting auxiliary system construction, and move up the middle section of the cage service and install the safety protection platform to ensure that the extension of the auxiliary shaft is not affected by the operation of the cage and ensure the construction safety. And the impact of the upper and lower tank cage transport personnel during construction can be minimized.
references:
[1]GB50653-2011. Non-ferrous metal mine roadway construction specification [S].
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[3] Liu Zhiqiang. Research on key technologies of large diameter anti- drilling rig [D]. Beijing: Beijing University of Science and Technology, 2015.
[4] Li Laiyun. Anti-well method to extend the vertical shaft example [J]. Mining Research and Development, 1999 (S1): 8-9, 13.