0 Introduction
During the construction of the shaft, due to geological conditions, seasonality and engineering quality, there will be water inrush or water seepage in the wellbore wall. The water in the well wall will not only worsen the working environment, affect the construction progress, but also corrode the well support lining and wellbore equipment. Affect the wellbore safety and stability [1-2]. At present, domestic water supply control for shaft wells usually adopts measures such as post-grouting water shut-off, wall front water cut-off, air duct cloth retaining water, well wall rework and well wall cofferdam water guiding [3-5], and the above measures exist. Long and large amount of engineering or passive prevention. Case for the small section of shaft construction period of tension but also has a wall of water gushing problem, a number of construction dark shaft Dahongshan iron ore pass-breaking innovation system uses a segmented wall after water cut guide prevention and control technology, making the shaft wall shower gushing water problem It has been effectively solved, construction investment is small, and the treatment effect is remarkable.
1 Project Overview
Yuxi Dahongshan Iron ore zone I, copper 1,500,000 t / a slip Mining Engineering breaking system 1 # hoistway square shaft, located on the south side chute, which is a cross-sectional wellbore net 3.7m × 3.2m, design 300mm Thick concrete, the height of the wellbore is about 200m. The elevator shaft adopts short section excavation. Considering that the height of the wellbore is large and the upper and lower joints of the wellbore have been formed, the construction method of the small well guiding boring machine is adopted. According to the drilling data of the anti- drilling rig , the surrounding rock of the elevator shaft is mostly dolomite marble slate , schist, massive, thin layer, slightly weathered, poor rock quality, and the rock mass is mostly massive. The development of joint fissures, including bedrock weathering fissures, abundant water, continuous gushing point distribution length of about 100m, the type of gushing water is mainly bedrock fissure water, and the hydraulic connection with the chute and 380 horizontal roadway is tight, and the average water inflow of the whole wellbore is predicted. Up to 20m3/h.
Considering that the length of the gushing section of the elevator shaft is large and the gushing point is scattered, the post-grouting and water-blocking period is long. Therefore, it is decided to use the segmented wall and intercepting water prevention technology to introduce the surrounding rock water into the 140 water tank to ensure the wellbore concrete. Support quality.
2 Shaft section interception water prevention and control program
The length of the gushing section of the 1# elevator shaft of Dahongshan Iron Mine Slip System is long. In order to ensure the effect of preventing water, the sectioned water interception is adopted for the wellbore of the gushing water section. The height of each 8~10m is a section, the bottom of each section. An annular trough is arranged in the entire circumference of the well wall outside the design excavation section, and the water in each section flows into the bottom trough of the section, and then the centralized water main pipe is buried in the trough to guide the water in the annular trough. Outside the concrete, and connected with the water pipe outside the concrete, Figure 1 is the section of the elevator shaft intercepting water. When the construction hanging plate falls to the segment, the upper and lower segmental water pipes are connected, and the water in the well wall is led down to the water tank at the bottom of the elevator shaft 140 according to the above method.
3 Shaft section intercepting water construction technology
3.1 Layout ring intercepting trough
Starting from the position where the wellbore has water inrush, the wellbore is constructed by short-drilling and short-span method. Each wellbore is divided into 8~10m sections. After the section of the wellbore is completed, the surrounding rock behind the wellbore wall at the bottom of each section is completed. A ring-shaped trough with a height of 600mm×depth of 800mm (excluding the thickness of 300mm of concrete) is set in the circle, and the working face of the bottom of the elevator shaft should be kept at a distance of more than 2m.
3.2 laying operation platform
After the annular trough is formed, the Φ50mm steel pipe and the fastener are used to erect the steel pipe frame from the bottom of the elevator shaft to the starting position of the segment. The arrangement spacing of the pipe rack is 1m×1m. A platform is laid on the top of the steel pipe frame (length 2000 mm × width 300 mm × thickness 50 mm) as an operating platform for installing the water barrier.
3.3 Making a water barrier
In order to ensure the quality of the concrete and minimize the leakage of water from the wellbore wall, a 30mm thick pine board covered with a 3mm thick steel plate is used to isolate the concrete from the rock wall as a water barrier.
The pine board aquifer can introduce this piece of water into the bottom annular trough. In order to prevent the water from seeping out from the gap between the lap joints of each piece of water-repellent board, a lap joint of not less than 400 mm wide is used on both sides of the lap joint of the pine board to close the gap, and the two pieces are overlapped. The wooden boards are connected together, and the overlapping length between the pine wood board and the two overlapping wooden boards is not less than 200 mm, and the overlapping wooden boards are fixed on the well wall by Φ14 mm×120 mm expansion bolts, and the spacing between each expansion bolt is 200 mm. The upper and lower spacing of the expansion bolts is 600 mm.
A Φ32mm water diversion steel pipe is buried in the concentrated water inrush point, and a 5-inch water diversion hose is directly introduced into the annular trough water tank, as shown in Fig. 2. Because the connection between the upper and lower adjacent segments is inconvenient to use the wooden board to reserve the connection, the connection between the adjacent segments is connected by a rubber joint with a thickness of 5 mm × a width of 1000 mm × a length of 3000 mm, and the rubber head is fixed with a steel nail on the previous one. On the pine board at the bottom of the section, the other end is reserved 300m outside the concrete retaining wall to connect with the lower layer of pine wood, and the overlap of each rubber is not less than 300mm.
After the water-repellent layer is completed, the concrete support of the shaft wall is carried out from the bottom to the top. When the support is to the position of the intercepting trough, a 240 mm wide concrete wall is first built in the trough near the wellbore to prevent the concrete wall from being built. Enter the trough and lay a layer of 300mm thick concrete on the bottom of the trough to shape the bottom of the trough.
3.4 Installation of the water conduit
A Φ159mm steel pipe is pre-embedded in the annular trough at the stairwell side of the permanent building of the elevator shaft as a water conduit, and the water in the annular trough is led to the outside of the well wall. The length of the water guiding pipe is 800mm, and the outer end of the well wall is reserved for the outer welded flange of the outer section of 100mm. The remaining length of 700mm is reserved in the wall of the shaft and in the annular intercepting trough. After the pilot pipe is completed, the segmented concrete is completely poured, and the height of each pouring in the section is 1 m.
After this section is completed, the aquifer is installed on the lower section of the well wall by the same method as described above. When the hanging plate falls to the lower section, the vertical water pipe of the upper section and the lower section is connected to the vertical guide pipe by using a vertical steel pipe of Φ159 mm. Install a Φ30mm mortar anchor on every 3m of the shaft wall on both sides of the vertical guide pipe and make a special steel pipe to fix the vertical guide pipe.
Use the above steps to gradually lead the vertical guide pipe into the 140 horizontal water tank. Table 1 shows the material consumption required for water interception construction per 100m water inrush section.
4 conclusion
The sectional wall intercepting water prevention and control technology is an active water control method for the shaft construction through the aquifer section. Compared with the domestic traditional well wall water control measures, it has the characteristics of simple construction and remarkable treatment effect, and the slipping system 1# elevator After the well is treated by this technology, the shaft wall of the shaft is basically waterless, which effectively solves the problem of water inrush in the well wall. The sectional wall intercepting water prevention and control technology arranges the annular intercepting trough inside the surrounding rock behind the borehole wall, and has high efficiency of water inflow into the aquifer, and the water control effect is directly effective, and the intercepting trough does not affect the normal use area of ​​the elevator shaft. It is beneficial to the shaft lifting; the technology is the advanced treatment of the wellbore water inrush, the related waterproofing facilities and the shaft wall of the shaft are built at the same time, there is no damage to the well wall, the added engineering quantity is small, and good economic and social benefits can be obtained.
references:
[1] Sun Bingshan, Zhang Yue, Zhu Hongli, et al. Station Street Coal Mine Shaft Construction on integrated water control technology [J]. Coal Technology, 2014, 33 (7): 248-250.
[2] Tong Hongchang, Li Guodong, Gu Ling. Post-wall grouting and water control technology under large and high water conditions in vertical shaft wellbore [J]. Well Construction Technology, 2008, 29(3): 7-9.
[3] Liu Yangping, Yan Lihong, Wang Shaowen. Application of the grouting Baoshan lead zinc ore skip main shaft construction [J]. Mining Technology, 2014, 14(4): 72-74.
[4] Wang's duties, Wu Xinguang. Pre-grouting construction of vertical shaft working face [J]. Well Construction Technology, 2014, 35(5): 16-18.
[5] Cai Lianjun, Kong Lingjie, Xie An. Application of water intercepting technology of annular water tank in treating wellbore water [J]. Zhongzhou Coal, 2011 (12): 83-84
Article source: Mining Technology; 2017.17(3)
Author: He Duanhua; new County of Hunan Province, Hunan Administration of Work Safety New County 422700;
Li Chuanming; Hunan Yushao Construction Engineering (Group) Co., Ltd. Loudi, Hunan 417000, China
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