A method for gas extraction in inclined shafts of extra-long highway tunnels

Abstract

The present invention discloses a method for constructing an inclined shaft gas extraction for an extra-long highway tunnel, the method comprising the following steps: step S1: before tunnel excavation, select a coal seam with a gas content that meets a predetermined amount, determine the inner diameter of the inclined shaft section communicating with the coal seam, and determine the angle θ between the inclined shaft section and the tunnel extension direction; step S2: according to the inner diameter and angle θ determined in step S1, drill from the mountainside stratum toward the direction close to the coal seam until reaching the communicating surface communicating with the coal seam, forming an inclined shaft section, and the tunnel excavation operation is synchronously carried out according to the construction schedule; step S3: start drilling from the communicating surface to the coal seam, forming a plurality of inclined shaft extraction holes extending into the interior of the coal seam; step S4: extract gas from the inclined shaft extraction hole and discharge it to the outside of the mountainside stratum. The present invention drills the tunnel and the inclined shaft section synchronously, and the construction personnel will reach the communicating surface one step earlier to extract gas, so that the gas on the coal seam can be extracted in advance before the tunnel passes through the coal seam, saving engineering investment.

Description

[Technical field]

[0001] The present application relates to the technical field of tunnel construction, and in particular to a method for constructing an inclined shaft for gas extraction in an extra-long highway tunnel. [Background technology]

[0002] With the continuous improvement of the scale and technology of tunnel and underground engineering construction in my country, long and large highway tunnels continue to emerge, especially tunnels with high gas content, which bring potential gas disaster risks to tunnel construction. The gas extraction method of the existing technology drills multiple well sections for gas extraction in high-content coal seams. However, during tunnel construction, construction workers will not start drilling well sections for gas extraction until they encounter coal seams. At this time, construction workers will stop tunnel construction to drill coal seams and extract gas, which seriously affects the construction period. For every day of delay in the construction period, the construction cost will increase exponentially. [Summary of the invention]

[0003] The invention proposes a gas extraction construction method for an inclined shaft of an extra-long highway tunnel, so as to solve the problem that the gas extraction method in the prior art affects the construction period.

[0004] To achieve the above object, the present invention provides the following technical solution: a method for gas extraction in an inclined shaft of an extra-long highway tunnel, the method comprising the following steps:

[0005] Step S1: before tunnel excavation, geological exploration is carried out to determine the location of the coal-bearing strata, select a coal seam whose gas content meets a predetermined amount, and determine the inner diameter of the inclined shaft section connected to the coal seam and the angle θ between the inclined shaft section and the extension direction of the tunnel according to geological exploration data;

[0006] Step S2: according to the inner diameter and angle θ determined in step S1, drilling is carried out from the mountainside stratum toward the direction close to the coal seam until reaching the communicating surface with the coal seam, forming the inclined shaft section, and the tunnel excavation operation is carried out synchronously according to the construction schedule;

[0007] Step S3: drilling into the coal seam from the communicating surface to form a plurality of inclined well drainage holes extending into the coal seam;

[0008] Step S4: extracting gas from the extraction hole of the inclined well and discharging it to the outside of the mountainside formation through the inclined well section.

[0009] As described above, in the inclined shaft gas extraction construction method for an extra-long highway tunnel, before step S3, the gas extraction control area is calculated and determined along its circumferential direction with the tunnel as the base point, and its position and volume at least cover the tunnel and the coal seam, and the inclined shaft extraction hole is located within the gas extraction control area.

[0010] In the above-mentioned inclined shaft gas extraction construction method for an extra-long highway tunnel, in step S3, the end point of the inclined shaft extraction hole is located on the edge of the coal seam or on the edge of the gas extraction control area.

[0011] As described above, in the inclined shaft gas extraction construction method for an extra-long highway tunnel, in step S1, the number of the inclined shaft extraction holes is not less than 4.

[0012] In the above-mentioned inclined shaft gas extraction construction method for an extra-long highway tunnel, in step S1, the angle θ does not exceed 90°.

[0013] As described above, in the inclined shaft gas extraction construction method for an extra-long highway tunnel, in step S4, after the gas is extracted, the gas extraction volume, concentration, pressure difference, temperature and air pressure need to be monitored.

[0014] The above-mentioned inclined shaft gas extraction construction method for an extra-long highway tunnel further includes the following steps after step S4:

[0015] Step S5, using a Marisan sealing bag formed by Marisan grouting material to seal the inclined well extraction hole.

[0016] Compared with the prior art, this application has the following advantages:

[0017] 1. The present invention realizes synchronous drilling of the tunnel and the inclined shaft section. Generally speaking, in the operation of an extra-long highway tunnel, the distance from the inclined shaft section to the coal seam is shorter than the distance from the tunnel to the coal seam, so the construction personnel will reach the communicating surface one step earlier to extract the gas, so that the gas on the coal seam can be extracted in advance before the tunnel passes through the coal seam. The process connection is compact, the operability is strong, the project investment is saved, and good conditions are provided for rapid and safe coal uncovering, which solves the problem that the gas extraction method in the prior art affects the construction period.

[0018] 2. The present invention drills into the mountainside stratum and extends to the coal seam. When the gas needs to be extracted, the gas is discharged outside the mountainside stratum. Most of the gas can be discharged directly to the top of the mountain before the gas enters the construction environment, avoiding the problem of traditional coal drilling discharge method of discharging gas into the tunnel construction environment, reducing the gas concentration in the construction environment, and reducing the risk of disasters caused by gas.

[0019] 3. The present invention realizes the centralized one-time pre-gas extraction of multiple coal seams in the coal-bearing stratum section through multiple divergent inclined well extraction holes, basically realizing the section-by-section elimination of coal-bearing strata gas. Compared with the traditional coal uncovering method which requires coal seam discharge one by one, it reduces the construction period and the amount of drilling construction.

Brief Description of the Drawings

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for describing the embodiments are briefly introduced below.

[0021] Figure 1 The invention discloses a gas extraction construction method for an inclined shaft of an extra-long highway tunnel;

[0022] Figure 2 yes Figure 1 A schematic diagram of the drilling structure in the method shown;

[0023] Figure 3 yes Figure 2 A is an enlarged view of the middle image. [Specific implementation method]

[0024] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0025] When the embodiments of the present invention mention ordinal numbers such as "first" and "second", unless they do express the meaning of order according to the context, they should be understood as being merely for the purpose of distinction.

[0026] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] like Figure 1-3 As shown, a method for extracting gas from an inclined shaft of an extra-long highway tunnel comprises the following steps:

[0028] Step S1: before excavating the tunnel 1, geological exploration is carried out to determine the location of the coal-bearing strata, and a coal seam 3 with a gas content that meets a predetermined amount is selected. Based on the geological survey data, the inner diameter of the inclined shaft section 2 communicating with the coal seam 3 is determined, and the angle θ between the inclined shaft section 2 and the extension direction of the tunnel 1 is determined;

[0029] Step S2: according to the inner diameter and angle θ determined in step S1, drilling is carried out from the mountainside stratum 7 toward the direction close to the coal seam 3 until reaching the communicating surface 5 communicating with the coal seam 3, forming the inclined shaft section 2, and the tunnel 1 excavation operation is carried out synchronously according to the construction schedule;

[0030] Step S3: drilling into the coal seam 3 from the communicating surface 5 to form a plurality of inclined well drainage holes 4 extending into the coal seam 3;

[0031] Step S4: extracting gas from the extraction hole 4 of the inclined well and discharging it to the outside of the mountainside formation 7 through the inclined well section 2.

[0032] In this embodiment, compared with the traditional coal mining construction of the extra-long tunnel 1, after the main tunnel of the tunnel 1 is excavated into the coal seam area, it is necessary to stop work for coal seam gas control, and excavation can be continued only after the control meets the standards. The present invention drills the tunnel and the inclined shaft section simultaneously. Generally speaking, in the operation of an extra-long highway tunnel, the distance from the inclined shaft section to the coal seam is smaller than the distance from the tunnel to the coal seam, so the construction personnel will reach the connecting surface one step earlier to extract the gas, so that the gas on the coal seam can be extracted in advance before the tunnel passes through the coal seam. The process connection is compact, the operability is strong, the project investment is saved, good conditions are provided for rapid and safe coal mining, and the problem that the gas extraction method in the prior art affects the construction period is solved.

[0033] In this embodiment, compared with the traditional coal drilling discharge that discharges gas into the tunnel construction environment, which easily causes the gas concentration in the construction environment to exceed the limit, the present invention directly extracts the gas to a high place outside the tunnel for discharge, reduces the ventilation time of the tunnel 1, greatly reduces the energy consumption of the equipment, and can effectively reduce the construction safety risk caused by the excessive gas in the tunnel 1.

[0034] In this embodiment, under accurate geological exploration, the parameters of the inclined well are determined, the inclined well is drilled in advance for gas extraction, and the gas parameters are monitored in real time during the gas extraction process to further ensure the safety of the gas extraction process. In addition, when selecting the specific coal seam 3, in addition to considering the coal seam gas parameters, it is also necessary to select a coal seam with a low water content in the roof or floor to avoid extracting only water when extracting gas.

[0035] Furthermore, before step S3, taking the tunnel 1 as a base point, a gas extraction control area 6 is calculated and determined along its circumferential direction, and its position and volume at least cover the tunnel 1 and the coal seam 3, and the inclined shaft extraction hole 4 is located within the gas extraction control area 6.

[0036] In this embodiment, when selecting the gas extraction control area 6, attention should be paid to the selected range, and the range should not affect the residual gas content in the tunnel 1 after gas extraction. The gas extraction control area 6 is equivalent to a horizontally placed cylinder, and its bottom surface can be circular, elliptical or irregular. However, when selecting the gas extraction control area 6, the contour line of the tunnel 1 should be used as the axis, and the distance between the left and right sides of the gas extraction control area 6 and the left and right sides of the contour line of the tunnel 1 should be controlled to be not less than 12m, and the gas extraction control area 6 should be controlled to be not less than 12m. The distance between the bottom of zone 6 and the bottom of the contour line of the tunnel 1 is not less than 12m, the distance between the arch that controls the gas extraction control zone 6 and the arch that controls the contour line of the tunnel 1 is not less than 12m, and the minimum normal distance from the gas extraction control zone 6 to the tunnel contour line is not less than 5m. The gas extraction control zone 6 is planned according to the above data. The larger the gas extraction control zone 6 is, the larger the range of gas extraction will be, and the residual content of gas in the tunnel 1 will be lower, but at the same time, the construction cost and construction period will also be affected.

[0037] Furthermore, in step S3 , the end point of the inclined shaft drainage hole 4 is located on the edge of the coal seam 3 or on the edge of the gas drainage control area 6 .

[0038] In this embodiment, the inclined shaft extraction and prevention holes 4 are of a blowout divergent type, and the starting points of every two inclined shaft extraction and prevention holes 4 are separated by a certain distance, and the starting point of the inclined shaft extraction and prevention holes 4 is actually a surface with a smaller area, but this area can be ignored for the communicating surface 5. It is defined as a point, and the end point of the inclined shaft extraction and prevention hole 4 only needs to reach a point on the edge of the coal seam 3 or a point on the edge of the gas extraction and prevention area 6, otherwise it will affect the construction period and increase the construction cost.

[0039] In this embodiment, when the tunnel 1 is about to be drilled into the coal seam 3, the construction must be carried out strictly in accordance with the four-in-one steps. This is to effectively prevent the gas content that may remain in the tunnel from causing a considerable risk of harm due to insufficient gas extraction, thereby ensuring the safety of construction workers.

[0040] Furthermore, in step S3, the number of the inclined well extraction holes 4 is not less than 4.

[0041] In this embodiment, the number of the inclined shaft pumping and prevention holes 4 will also affect the construction period. Too many holes will increase the construction cost, and too few holes will lead to insufficient gas extraction. After repeated calculations and practices, the number of the inclined shaft pumping and prevention holes 4 can be less than 4, which will neither affect the construction period nor cause insufficient gas extraction.

[0042] Furthermore, in step S1, the angle θ does not exceed 90°.

[0043] In this embodiment, most of the coal seams 3 exist in the form of inclined layers, and the vertical distance to the inclined layers is the shortest. The earlier the inclined shaft section 2 reaches the coal seam 3, the earlier the gas extraction can be carried out without affecting the progress of tunnel construction. At the same time, the vertical distance to the inclined layers will also enable the inclined layer extraction holes to extend more fully in the coal seam 3. After repeated calculations and practices, an angle θ exceeding 90° will affect the construction progress and prevent the inclined layer extraction holes from extending more fully in the coal seam 3.

[0044] Furthermore, in step S4, after the gas is extracted, the extraction volume, concentration, pressure difference, temperature and gas pressure of the gas need to be monitored.

[0045] In this embodiment, the purpose of monitoring various gas parameters is to confirm that the gas content in the tunnel is not high, thereby ensuring the safety of construction workers.

[0046] Furthermore, after step S4, the following steps are also included:

[0047] Step S5, using a Marisan sealing bag formed by Marisan grouting material to seal the inclined well extraction hole 4.

[0048] In this embodiment, after ensuring that the gas content is not high and the harm caused is not great, the inclined shaft pumping prevention hole 4 is sealed to stabilize the tunnel 1.

[0049] More preferably, only the inclined shaft drainage hole below the tunnel 1 is sealed, and the inclined shaft drainage hole above the tunnel 1 can be used for tunnel ventilation.

[0050] The working principle of the present invention is as follows:

[0051] Compared with the traditional coal mining construction of the extra-long tunnel 1, after the main tunnel of the tunnel 1 is excavated into the coal seam area, it is necessary to stop work for coal seam gas control, and excavation can be continued only after the control meets the standards. The present invention drills the tunnel and the inclined shaft section simultaneously. Generally speaking, for the operation of an extra-long highway tunnel, the distance from the inclined shaft section 2 to the coal seam 3 is smaller than the distance from the tunnel 1 to the coal seam 3, so the construction personnel will reach the connecting surface 5 one step earlier to drill the inclined shaft extraction and prevention hole 4 for extracting gas, so as to realize the advance extraction of gas on the coal seam 3 before the tunnel passes through the coal seam. When the excavation operation of the tunnel 1 is about to reach the coal seam, gas monitoring is no longer needed and excavation can continue in the direction close to the coal seam.

[0052] The above is an implementation method provided in combination with specific content, and it is not considered that the specific implementation of this application is limited to these descriptions. Any similarity or similarity with the method, structure, etc. of this application, or any technical deduction or replacement made on the premise of the concept of this application, shall be deemed to be within the scope of protection of this application.

Claims

1. A method for extracting gas from an inclined shaft in an extra-long highway tunnel, characterized in that: The method comprises the following steps: Step S1: before excavating the tunnel (1), geological exploration is carried out to determine the location of the coal-bearing strata, a coal seam (3) having a gas content that satisfies a predetermined amount is selected, and based on geological exploration data, the inner diameter of the inclined shaft section (2) communicating with the coal seam (3) is determined, as well as the angle θ between the inclined shaft section (2) and the extension direction of the tunnel (1) is determined; Step S2: according to the inner diameter and angle θ determined in step S1, drilling is performed from the mountainside stratum (7) in the direction close to the coal seam (3) until reaching the communicating surface (5) communicating with the coal seam (3), thereby forming the inclined shaft section (2), and the tunnel (1) excavation operation is performed synchronously according to the construction schedule; Step S3: drilling into the coal seam (3) from the communicating surface (5) to form a plurality of inclined well extraction holes (4) extending into the interior of the coal seam (3); Step S4: extracting gas from the extraction hole (4) of the inclined well and discharging it to the outside of the mountainside formation (7) through the inclined well section (2).

2. The method for gas drainage in an inclined shaft of an extra-long highway tunnel according to claim 1, characterized in that: Before step S3, taking the tunnel (1) as a base point, a gas extraction control area (6) is calculated and determined along its circumferential direction, and its position and volume at least cover the tunnel (1) and the coal seam (3), and the inclined shaft extraction hole (4) is located within the gas extraction control area (6).

3. The method for gas drainage in an inclined shaft of an extra-long highway tunnel according to claim 2, characterized in that: In step S3, the end point of the inclined shaft drainage hole (4) is located on the edge of the coal seam (3) or on the edge of the gas drainage control area (6).

4. The method for gas drainage in an inclined shaft of an extra-long highway tunnel according to claim 1, characterized in that: In step S3, the number of the inclined well extraction holes (4) is not less than 4.

5. The method for gas drainage in an inclined shaft of an extra-long highway tunnel according to claim 1, characterized in that: In step S1, the angle θ does not exceed 90°.

6. The method for gas drainage in an inclined shaft of an extra-long highway tunnel according to claim 1, characterized in that: In step S4, after the gas is extracted, the extraction volume, concentration, pressure difference, temperature and gas pressure of the gas need to be monitored.

7. The method for gas drainage in an inclined shaft of an extra-long highway tunnel according to claim 1, characterized in that: After step S4, the following steps are also included: Step S5, using a Marisan sealing bag formed by Marisan grouting material to seal the inclined well extraction hole (4).

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