AU2013354613A1

AU2013354613A1 - Method of local filling to control surface subsidence in worked-out area

Info

Publication number: AU2013354613A1
Application number: AU2013354613A
Authority: AU
Inventors: Xinqi CAO; Pan Li; Liqiang MA
Original assignee: China University of Mining and Technology CUMT
Current assignee: China University of Mining and Technology CUMT
Priority date: 2012-12-07
Filing date: 2013-12-05
Publication date: 2015-03-12
Anticipated expiration: 2033-12-05
Also published as: CN103016053A; WO2014086296A1; AU2013354613B2; ZA201500071B; CN103016053B

Abstract

A method of local filling to control surface subsidence in a gob. Metal nets are suspended at intervals from open-off cuts and on top plates behind a hydraulic bracket on a working surface along with coal cutting of a coal cutter and movement of the hydraulic bracket on the working surface, and filling bags are arranged; coal cutting is stopped after cutting is performed once by the coal cutter, and concrete is filled into the filling bags in the metal nets in sequence until a roof; cutting is continuously performed once by the coal cutter, metal nets are continuously suspended on top plates adjacent to the two sides of the filled area, filling is continuously performed to complete a filling cycle, and a row of filled bodies are formed in a gob parallel to the working surface; and coal cutting is continuously performed four to five times by the coal cutter, the following filling cycle is completed continuously, and the procedures are repeated until filling of the whole gob is completed and a plurality of rows of filled bodies are formed in the gob. The method is simple, and the filling cost is low. The top plates in the gob are supported uniformly at intervals; therefore, the stability of an overburden layer, in particular a key layer, can be improved, and surface subsidence and damage to buildings can be effectively prevented.

Description

Description Method of local filling to Control Surface Subsidence in Worked-out area Field of the Invention The present invention relates to coal mining field, in particular to a local filling method for controlling surface subsidence in worked-out areas where coil mining is carried out under railroads, water bodies, or constructions and the top plate of coal seam is stable. Background of the Invention In the coal mines production in China, the coal reserve under railroads, water bodies, and constructions is about 14 billion tons, which is enough for 10 mines with 10 million t/a annual yield to produce 140 years, wherein, the coal reserve under constructions is about 9 billion tons. How to mine the coal under constructions reasonably is always an important task for the coal mining enterprises in China. For surface subsidence control after mining, efforts are made in two aspects in China and foreign countries: subsidence-reduced mining and worked-out area roof overburden rock movement control. Subsidence-reduced mining techniques mainly include strip mining and board and pillar mining, wherein, strip mining is to divide a coal seam to be mined into regular strips, and then mine in alternate strips, so as to reduce surface subsidence. This technique is widely applied in China, the greatest advantage of it is that the existing mining process can still be used, the cost increase is small, the production control is easy, and the surface subsidence reducing effect is significant, the disadvantages mainly include low mining rate (usually 30%-50%) and severe resource loss. The board and pillar mining technique is a matured mining technique widely applied in USA, Australia, and South Africa, etc, it is a conventional mining method as well as a surface subsidence control means, and is applied in some mines in China, it can attain great economic benefit, but has disadvantages including low resource recovery rate and poor ventilation conditions, and is only applicable to coal seams where the geological conditions are relatively simple. Worked-out area roof overburden rock movement control techniques mainly include full filling technique, partial filling technique, separation seam grouting technique, and caving zone filling and grouting technique. The full filling technique is to fill a worked-out area with a filling material to form a filling body, so as to prevent roof caving and confine roof movement, it can effectively reduce surface subsidence and improve coal recovery rate, but has severe limitation owing to its high cost. The partial filling technique is to fill a worked-out area locally or fill separattion seam zones and caving zones and control mining subsidence by means of the key stratum structure of roof overburden rock, filling mass, and partial coal pillars in combination. The separation seam grouting technique is to determine the position of separation seam in the roof overburden rock on the basis of the basic law of movement in rock strata and drill from the surface to fill medium such as coal ash in the separation seam and thereby attain the purpose of surface subsidence control, with this method, surface grouting and underground mining can be carried out in parallel without interference with each other, but the application of this technique is limited, because it is difficult to ascertain the position and volume of separation seam. The caving zone grouting and filling technique is to fill grout to attain a filling and reinforcement effect before the caving gangues in a worked-out area is compacted, so as to support the roof overburden rock and thereby alleviate surface subsidence, but it is still in a research stage, and has not been widely applied yet. 1 Description Theoretically, filling the down-hole area with solid wastes such as gangue as the main filling material with fill mining techniques can reduce discharge of wastes such as gangue on one hand, and can alleviate mining subsidence on the other hand, so that the coal reserve under constructions can be mined, and the requirement for circular economy and green mining can be met. However, how to develop fill mining techniques that meet the characteristics and requirements of coal mines is still a question to be answered, wherein, how to reduce the cost of ill mining is the key problem to be solved for fill mining techniques in coal mines. The law of movement of stratified rocks in coal measures and the characteristics of control should be fully utilized in the study of fill mining techniques in coal mines. Relevant researches have shown: the main key stratum of roof overburden rock exercises control effect in the surface movement process, and fracture of the main key stratum will result in quick surface subsidence and severely increased subsidence, and the surface subsidence rate exhibits leap changes along with cyclic fractures of the main key stratum. Therefore, surface subsidence can be controlled effectively by controlling the main key stratum. Summary of the Invention Technical problem: the object of the present invention is to overcome the drawbacks in the prior art and provide a local filling method for controlling surface subsidence in a worked-out area, which is simple, easy to use, and low in cost. Technical solution: the local filling method for controlling surface subsidence in a worked-out area in the present invention comprises the following steps: a. arranging a concrete delivery pipeline in a hauling roadway of working face, installing a concrete delivery pump on the equipment train of the down-hole working face, hanging a filling pipeline connected to the concrete delivery pipeline on the tail beams of hydraulic bracket on the working face, arranging a plurality of filling areas at an interval between the hydraulic bracket at upper end and lower end of the working face, and arranging a discharge port on the filling pipeline at the position corresponding to each filling area; b. starting from the open-off cuts, hanging metal nets at an interval on the top plate behind the hydraulic bracket on the working face and arranging filling bags in the metal nets along with coal cutting of a coal cutter and movement of the hydraulic bracket on the working face; c. stopping coal cutting after the coal cutter completing a cut and advances obliquely, opening the concrete delivery pump and delivering concrete to the filling area through the concrete delivery pipeline via the filling pipeline; d. opening the discharge port on the filling pipeline in each filling area in sequence, filling concrete into the filling bags arranged in the metal nets till the concrete reaches the top plate, and sealing the filling bags; e. after the coal cutter completing the next cut, hanging metal nets on the top plates adjacent to two sides of the filled area, and arranging filling bags in the metal nets, then, repeating steps c and d to complete a filling cycle, in this way, a row of filling masses is formed in the worked-out area parallel to the working face; f. after the coal cutter completing 4-5 cuts continuously, repeating steps c, d, e to continue the next cycle of filling work, again and again, till the filling work is done in the entire worked-out 2 Description area and multiple rows of filling masses are formed in the worked-out area. Beneficial effects: based on a strip filling technique, the present invention employs a partial fill mining method, which is helpful for reducing the amount of filling material, filling workload, and filling cost. By changing the arrangement of filling masses, the top plate in the worked-out area is supported at an even interval, which is advantageous for stability of the top plate and key stratum. Since rectangular filling masses are arranged at an even interval in the worked-out area, the filling amount and filling cost are reduced, while the recovery rate is improved, in addition, the stability of the key stratum of roof overburden rock is improved, and thereby surface subsidence can be controlled effectively. The method is simple and low in cost. Brief Description of the Drawings Fig. lis a layout diagram of local filling in a worked-out area at a fully-mechanized mining working face according to the present invention. Among the figures: 1 - rail roadway on working face; 2 - hauling roadway on working face; 3 concrete delivery pipeline; 4 - filling pipeline; 5 - discharge port; 6 - scraper conveyer on working face; 7 - coal cutter; 8 - belt conveyer in hauling roadway; 9 - equipment train; 10 - filling mass. Detailed Description of the Embodiments Hereunder the present invention will be further detailed in an embodiment, with reference to the accompanying drawings: The local filling method for controlling surface subsidence in a worked-out area in the present invention is: a. first, arrange a concrete delivery pipeline 3 in a hauling roadway 2 on working face, install a concrete delivery pump on the equipment train 9 of down-hole working face, hang a filling pipeline 4 connected to the concrete delivery pipeline 3 on the tail beams of hydraulic bracket on the working face, arrange a plurality of filling areas at an interval between the hydraulic bracket at upper end and lower end of the working face, and arrange a discharge port 5 on the filling pipeline 4 at the position corresponding to each filling area; b. starting from the open-off cuts, hang metal nets at an interval on the top plate behind the hydraulic bracket on the working face and arrange filling bags in the metal nets along with the coal cutting of a coal cutter and movement of the hydraulic bracket on the working face , wherein, the length of the metal net on the sides perpendicular to the advance direction of the working face is 4-5m, and the width of the metal net on the sides parallel to the advance direction of the working face is 0.6-0.8m; c. stop coal cutting after the coal cutter completing a cut and advances obliquely, open the concrete delivery pump and deliver concrete to the filling area through the concrete delivery pipeline 3 via the filling pipeline 4 to the filling area; d. open the discharge port 5 on the filling pipeline 4 in each filling area in sequence, fill concrete into the filling bags arranged in the metal nets till the concrete reaches the top plate, and then seal the filling bags; e. after the coal cutter completing the next cut, hang metal nets on the top plates adjacent to two sides of the filled area, and arrange filling bags in the metal nets; then, repeat steps c and d to 3 Description complete a filling cycle in this way, a row of filling masses 10 is formed in the worked-out area parallel to the working face, wherein, the step length of the filling cycle is 1.2-1.6m, and can be adjusted according to the actual conditions of the on-site, so as to form filling masses 10 with appropriate strength; f. after the coal cutter complete 4-5 cuts continuously, the advance length is 2.4-4m and can be adjusted according to the actual conditions; repeat steps c, d, e to continue the next cycle of filling work, again and again, till the filling work is done in the entire worked-out area and multiple rows of filling masses 10 are formed in the worked-out area. 4

Claims

1. A local filling method for controlling surface subsidence in a worked-out area, comprising the following steps: a. arranging a concrete delivery pipeline (3) in a hauling roadway (2) on a working face, installing a concrete delivery pump on an equipment train on down-hole working face, hanging a filling pipeline (4) connected to the concrete delivery pipeline (3) on tail beams of hydraulic bracket on the working face, arranging a plurality of filling areas at an interval between the hydraulic bracket at upper end and lower end of the working face, and arranging a discharge port (5) on the filling pipeline (4) at a position corresponding to each filling area; b. starting from the open-off cuts, hanging metal nets at an interval on the top plate behind the hydraulic bracket on the working face and arranging filling bags in the metal nets along with coal cutting of a coal cutter and movement of hydraulic bracket on the working face; c. stopping coal cutting after the coal cutter completing a cut and advances obliquely, opening the concrete delivery pump and delivering concrete to the filling area through the concrete delivery pipeline (3) via the filling pipeline (4); d. opening the discharge port (5) on the filling pipeline (4) in each filling area in sequence, filling concrete into the filling bags arranged in the metal nets till the concrete reaches a top plate, and then sealing the filling bags; e. after the coal cutter completing a next cut, hanging metal nets on the top plates adjacent to two sides of the filled area, and arranging filling bags in the metal nets; then, repeating steps c and d to complete a filling cycle, in this way, a row of filling masses (10) is formed in the worked-out area parallel to the working face; f. after the coal cutter completing 4-5 cuts continuously, repeating steps c, d, e to continue the next cycle of filling work, again and again, till the filling work is done in the entire worked-out area and multiple rows of filling masses (10) are formed in the worked-out area. 5