Tunnel advance drilling harmful gas detection equipment and method

Abstract

The invention discloses tunnel advanced drilling harmful gas detection equipment and method, and relates to the technical field of tunnel construction. The tunnel advance drilling harmful gas detection equipment comprises a sleeve; a laser monitoring module is arranged on the sleeve and used for emitting laser in the sleeve in the axial direction of the sleeve and conducting distance measurement and monitoring the concentration of harmful gas. A shielding module is arranged on the sleeve and is used for periodically shielding laser emitted by the laser monitoring module; a gas flow rate monitoring module is arranged on the sleeve and used for monitoring the flow rate of harmful gas in the sleeve. The method can accurately detect the concentration of the harmful gas at the hole bottom of the advanced drill hole, and provides an accurate basis for evaluating the risk of the harmful gas in the tunnel.

Description

Technical Field

[0001] The present application relates to the technical field of tunnel construction, and in particular to a device and method for detecting harmful gases in advance drilling of a tunnel. Background Art

[0002] During tunnel construction, harmful gases often escape or gush out from the heading face or unsupported tunnel wall. When the harmful gases in the tunnel reach a certain concentration, they will cause a series of disasters, threaten the personal safety of workers, cause delays in construction, and even cause major engineering accidents.

[0003] In order to reduce the risk of harmful gases in tunnel construction, the method of advanced geological prediction is usually used to determine the danger of harmful gases in the tunnel before the formal excavation of the heading face.

[0004] There are two main methods for pre-detection of harmful gases in tunnels: one is to place sensors at the borehole mouth to detect the concentration of harmful gases; however, this detection method cannot accurately detect the concentration of harmful gases in the hole. The other is to seal the borehole for 24 hours after the pre-drilling is completed, and measure the concentration of harmful gases in the hole after 24 hours; however, this method cannot measure the actual concentration of harmful gases during excavation in the hole, and the construction efficiency is low, which affects the normal excavation and progress of the tunnel. Summary of the invention

[0005] The purpose of the present application is to provide a tunnel advance drilling harmful gas detection device and method to solve the problem that the concentration of harmful gases in the advance drilling cannot be accurately detected.

[0006] The technical solution adopted by this application to solve its technical problem is:

[0007] In a first aspect, a tunnel advance drilling harmful gas detection device is provided, comprising a casing; a laser monitoring module is provided on the casing, and the laser monitoring module is used to emit laser in the casing along the axial direction of the casing, and to measure the distance and monitor the concentration of harmful gases; a shielding module is provided on the casing, and the shielding module is used to periodically shield the laser emitted by the laser monitoring module; a gas flow rate monitoring module is provided on the casing, and the gas flow rate monitoring module is used to monitor the flow rate of harmful gases in the casing.

[0008] Furthermore, the laser monitoring module includes a laser gas sensor, a laser ranging sensor and a reflective prism arranged outside the casing. A laser hole is provided on the tube wall of the casing. The reflective prism is used to reflect the laser emitted by the laser gas sensor and the laser ranging sensor into the casing through the laser hole and propagate along the axial direction of the casing.

[0009] Furthermore, the laser monitoring module also includes a monitoring box connected to the sleeve, and the laser gas sensor, the laser ranging sensor and the reflective prism are arranged in the monitoring box.

[0010] Furthermore, the shielding module includes a driving member arranged outside the sleeve and a shielding member connected to the driving member. The tube wall of the sleeve is provided with an avoidance hole for avoiding the shielding member. The driving member is used to drive the shielding member to move and periodically shield the laser in the sleeve.

[0011] Furthermore, the gas flow rate monitoring module includes a flow rate monitoring box arranged outside the sleeve and a gas flow rate sensor arranged inside the flow rate monitoring box, and the flow rate monitoring box is communicated with the inner cavity of the sleeve.

[0012] Furthermore, it also includes a control module, which is connected to the laser monitoring module, the shielding module and the gas flow rate monitoring module respectively.

[0013] Furthermore, the sleeve is used to be sleeved on the drill rod, and the sleeve can move on the drill rod along the axial direction of the drill rod.

[0014] Furthermore, a water tank connected to the inner cavity of the sleeve is provided below the sleeve; the bottom of the inner cavity of the water tank has an upwardly extending water baffle, and forms a water outlet cavity and a sampling cavity located on both sides of the water baffle, a water outlet pipe connected to the water outlet cavity is provided at the lower end of the water tank, and a sampling tube connected to the sampling cavity is provided at the lower end of the water tank.

[0015] Furthermore, a horizontally arranged filter element is provided in the water tank above the water baffle, and a slag discharge door for opening and closing the chamber above the filter element is provided on the water tank.

[0016] In a second aspect, a method for detecting harmful gases in advance drilling of a tunnel is provided, using the device for detecting harmful gases in advance drilling of a tunnel provided in the first aspect, the method comprising:

[0017] S1. Connect one end of the casing to the orifice of the advance drilling hole;

[0018] S2, the laser monitoring module emits laser to the bottom of the advance drilling hole to obtain the concentration c1 of harmful gas from the laser monitoring module to the bottom of the advance drilling hole;

[0019] S3, after time t1, the shielding module shields the laser in the casing, the laser monitoring module emits laser to the shielding module, obtains the concentration c2 of harmful gas from the laser monitoring module to the shielding module and the distance d2 from the laser monitoring module to the shielding module, and the gas flow rate monitoring module monitors the flow rate v of harmful gas in the casing;

[0020] S4, after time t2, the shielding module releases the laser in the casing, and the laser monitoring module emits laser to the bottom of the advance drilling hole, and obtains the concentration c3 of harmful gas from the laser monitoring module to the bottom of the advance drilling hole;

[0021] S5. Calculate the concentration of harmful gases at the bottom of the advance drilling hole according to the data obtained in steps S2, S3, and S4.

[0022] Beneficial effects of this application:

[0023] The tunnel advance drilling harmful gas detection equipment and method provided in the embodiment of the present application can accurately detect the harmful gas concentration at the bottom of the advance drilling hole in real time with the drilling rig, thereby improving construction efficiency and providing an accurate basis for the evaluation of the harmful gas hazard in the tunnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 is a stereoscopic diagram of a tunnel advance drilling harmful gas detection device provided in an embodiment of the present application;

[0026] Figure 2 is a cross-sectional view of a tunnel advance drilling harmful gas detection device provided in an embodiment of the present application;

[0027] Figure 3 It is a partial enlarged view of the tunnel advance drilling harmful gas detection device provided in the embodiment of the present application;

[0028] Figure 4 This is a state diagram of the tunnel advance drilling harmful gas detection device provided in the embodiment of the present application when performing detection.

[0029] Reference numerals:

[0030] 10- casing;

[0031] 101-laser hole; 102-avoidance hole; 103-connecting hole;

[0032] 11-Laser monitoring module;

[0033] 111-laser gas sensor; 112-laser distance sensor; 113-reflection prism; 114-monitoring box; 115-power supply;

[0034] 12- occlusion module;

[0035] 121-driving member; 122-shielding member;

[0036] 13- Gas flow rate monitoring module;

[0037] 131-flow rate monitoring box; 132-gas flow rate sensor;

[0038] 14- control module;

[0039] 15-drill pipe;

[0040] 16- water tank;

[0041] 161-water outlet chamber; 162-sampling chamber;

[0042] 17-waterproof board;

[0043] 18-water outlet pipe;

[0044] 19- sampling tube;

[0045] 20- filter element;

[0046] 21-slag discharge door;

[0047] 22-Flow meter;

[0048] 23-sampling valve;

[0049] 24- Palm surface;

[0050] 25-Advance drilling;

[0051] 26-Flange assembly. DETAILED DESCRIPTION

[0052] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. In the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0053] In the description of this application, the terms "upper", "lower", "left", "right", "front", "back", "inside", "outside" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on this application. Unless otherwise specified, the above-mentioned directional descriptions can be flexibly set in the process of actual application under the condition that the relative positional relationship shown in the accompanying drawings is satisfied.

[0054] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" 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 direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0055] During tunnel construction, harmful gases often escape or gush out from the face or unsupported tunnel wall. When the harmful gases in the tunnel reach a certain concentration, they will cause a series of disasters, such as explosions caused by methane and hydrogen, poisoning caused by carbon monoxide, hydrogen sulfide, and sulfur dioxide, and suffocation caused by carbon dioxide, etc., threatening the personal safety of workers, causing delays in construction schedule, and even causing major engineering accidents.

[0056] In order to reduce the risk of harmful gases in tunnel construction, the method of advanced geological prediction is usually used to determine the danger of harmful gases in the tunnel before the formal excavation of the heading face.

[0057] The existing method for advanced detection of harmful gases in tunnels is mainly to arrange sensors at the openings of drill holes to detect the concentration of harmful gases. Among them, there are mainly two types of sensors: contact sensors and laser sensors based on laser absorption spectroscopy.

[0058] Due to the great depth of advance drilling, the deepest hole can reach hundreds of meters. When the harmful gases gushing out from the newly revealed strata flow to the hole mouth, the concentration difference between the hole mouth and the hole bottom is large, resulting in large errors in the method of using contact sensors to detect gas concentration at the hole mouth.

[0059] Although laser sensors based on laser absorption spectroscopy can solve the problem of long-distance detection of harmful gases, the concentration of harmful gases detected by this type of sensor is the average concentration per meter, in units of ppm·m; this means that even if the concentration of harmful gases at the bottom of the hole is very high, the detection result may not be high after being averaged over a distance of hundreds of meters, resulting in low accuracy.

[0060] Another existing method for advance detection of harmful gases in tunnels is to seal the borehole for 24 hours after the advance drilling is completed, and measure the concentration of harmful gases in the hole 24 hours later; however, this method cannot measure the actual concentration of harmful gases during excavation in the hole, and the construction efficiency is low, affecting the normal excavation and progress of the tunnel.

[0061] Based on this, the embodiment of the present application provides a tunnel advance drilling harmful gas detection device and method, which is used to accurately detect the concentration of harmful gases at the bottom of the advance drilling hole, and provide an accurate basis for the evaluation of the danger of harmful gases in the tunnel. Among them, harmful gases include but are not limited to methane, hydrogen, carbon monoxide, hydrogen sulfide, sulfur dioxide, carbon dioxide, etc.

[0062] See also Figure 1 , Figure 2 , Figure 3 The embodiment of the present application provides a tunnel advance drilling harmful gas detection device, including a casing 10; a laser monitoring module 11 is provided on the casing 10, and the laser monitoring module 11 is used to emit laser in the casing 10 along the axial direction of the casing 10, and to measure the distance and monitor the concentration of harmful gases; a shielding module 12 is provided on the casing 10, and the shielding module 12 is used to periodically shield the laser emitted by the laser monitoring module 11; a gas flow rate monitoring module 13 is provided on the casing 10, and the gas flow rate monitoring module 13 is used to monitor the flow rate of harmful gases in the casing 10.

[0063] See also Figure 1 , Figure 2 The casing 10 is a structure with a closed left end and an open right end. When in use, the open end of the casing 10 is connected to the orifice of the advanced borehole 25 to guide the harmful gas and groundwater in the advanced borehole 25 to flow into the casing 10. Of course, the casing 10 can also be a structure with open ends, which is not limited here.

[0064] Exemplarily, the casing 10 is used to be sleeved on the drill rod 15, and the casing 10 can move on the drill rod 15 along the axial direction of the drill rod 15. For example, the casing 10 can be connected to the drill rod 15 through a flange assembly 26, so that the casing 10 is installed and supported by the drill rod 15.

[0065] See also Figure 1 , Figure 2 The laser monitoring module 11 and the shielding module 12 are arranged on the casing 10 at intervals along the axial direction of the casing 10 .

[0066] The laser emitted by the laser monitoring module 11 can propagate in the casing 10, and the propagation direction of the laser in the casing 10 is parallel to the axial direction of the casing 10. The laser can not only realize distance measurement, but also realize the monitoring of harmful gas concentration based on the principle of laser absorption spectrum.

[0067] The shielding module 12 can achieve periodic shielding of the laser on the laser propagation path in the sleeve 10. That is, the shielding module 12 can regularly and regularly shield the laser so that the laser is completely blocked within a specific time interval.

[0068] The gas flow rate monitoring module 13 is disposed on the sleeve 10 to monitor the flow rate of harmful gas flowing into the sleeve 10. The gas flow rate monitoring module 13 can be disposed between the laser monitoring module 11 and the shielding module 12.

[0069] The laser monitoring module 11 may include a laser gas sensor 111 and a laser ranging sensor 112 disposed in the casing 10; the laser gas sensor 111 is used to emit laser along the axial direction of the casing 10 to monitor the concentration of harmful gases; the laser ranging sensor 112 is used to emit laser along the axial direction of the casing 10 to achieve ranging.

[0070] See also Figure 3 The laser monitoring module 11 includes a laser gas sensor 111, a laser distance sensor 112 and a reflective prism 113 arranged outside the casing 10. A laser hole 101 is arranged on the wall of the casing 10. The reflective prism 113 is used to reflect the laser emitted by the laser gas sensor 111 and the laser distance sensor 112 into the casing 10 through the laser hole 101 and propagate along the axial direction of the casing 10. Among them, the laser gas sensor 111 is used to monitor the concentration of harmful gases, and the laser distance sensor 112 is used to measure distance; the laser gas sensor 111 and the laser distance sensor 112 are located at the same position in the axial direction of the casing 10. Figure 3 The dotted line in the figure is the propagation path of the laser.

[0071] Accordingly, by arranging a laser gas sensor 111, a laser ranging sensor 112 and a reflective prism 113 outside the casing 10, and arranging a laser hole 101 on the wall of the casing 10, not only the entire laser monitoring module 11 is easy to install and maintain, but also the installation space inside the casing 10 is avoided to be occupied, and the groundwater and debris flowing into the casing 10 during the drilling process are prevented from contacting with the sensor and damaging the sensor, thereby improving the service life of the laser monitoring module 11.

[0072] See also Figure 3 The laser monitoring module 11 also includes a monitoring box 114 connected to the casing 10 , and the laser gas sensor 111 , the laser distance sensor 112 and the reflective prism 113 are arranged in the monitoring box 114 .

[0073] Accordingly, the monitoring box 114 can provide physical protection for the laser gas sensor 111, the laser ranging sensor 112 and the reflective prism 113, preventing damage to the equipment by dust, moisture, vibration and other environmental factors, thereby extending the service life. The monitoring box 114 can also reduce external electromagnetic interference and optical interference to ensure the measurement accuracy and stability of the sensor. Integrating all components in a monitoring box 114 makes the entire laser monitoring module 11 more compact, easy to install and maintain, and can also reduce the complexity and time of on-site installation.

[0074] See also Figure 3 The laser monitoring module 11 further includes a power supply 115 disposed in the monitoring box 114 , and the power supply 115 is connected to the laser gas sensor 111 and the laser ranging sensor 112 respectively.

[0075] Accordingly, integrating the power supply 115 into the monitoring box 114 can reduce the complexity of the external power supply line, simplify the wiring and installation process, and avoid the wiring problem of multiple power supply lines in the external environment. The design of the integrated power supply 115 makes the expansion of the laser monitoring module 11 more flexible. If more sensors or other components need to be added, they only need to be connected and matched in the monitoring box 114 without rewiring and installing an external power supply.

[0076] The shielding module 12 may be disposed in the sleeve 10 , and the shielding module 12 may be turned over, moved, rotated, and other functions to achieve periodic shielding of the laser.

[0077] See also Figure 3 The shielding module 12 includes a driving member 121 disposed outside the sleeve 10 and a shielding member 122 connected to the driving member 121. The wall of the sleeve 10 is provided with an avoidance hole 102 for avoiding the shielding member 122. The driving member 121 is used to drive the shielding member 122 to move and periodically shield the laser in the sleeve 10. The movement mode of the shielding member 122 can be moving, rotating, etc., which is not specifically limited here.

[0078] Exemplarily, the driving member 121 may include a motor, the shielding member 122 may include a shielding plate, and the output shaft of the motor is connected to the shielding plate. When in use, the output shaft of the motor drives the shielding plate to rotate, and then the shielding plate is used to periodically shield the laser in the sleeve 10. The driving member 121 may also include a linear drive, and the shielding member may include a shielding plate, and the piston rod of the linear drive is connected to the shielding plate; when in use, the piston rod of the linear drive extends and retracts to drive the shielding plate to move back and forth, and then the shielding plate is used to periodically shield the laser in the sleeve 10.

[0079] Accordingly, the shielding module 12 is integrated outside the casing 10 , which not only makes the entire shielding module 12 easy to install and maintain, but also avoids occupying the installation space inside the casing 10 .

[0080] The gas flow rate monitoring module 13 may include a gas flow rate sensor disposed in the sleeve 10. When the harmful gas flows into the sleeve 10, the gas flow rate sensor is used to monitor the flow rate of the harmful gas.

[0081] See also Figure 3 The gas flow rate monitoring module 13 includes a flow rate monitoring box 131 disposed outside the casing 10 and a gas flow rate sensor 132 disposed inside the flow rate monitoring box 131. The flow rate monitoring box 131 is connected to the inner cavity of the casing 10. Exemplarily, a connecting hole 103 is provided on the top of the tube wall of the casing 10. The flow rate monitoring box 131 is connected to the inner cavity of the casing 10 through the connecting hole 103. A plurality of overflow holes may be provided on the top of the flow rate monitoring box 131 so that the harmful gas in the casing 10 can overflow from the overflow holes.

[0082] Accordingly, the gas flow rate sensor 132 can be used to monitor the flow rate of harmful gases flowing into the casing 10. By arranging the gas flow rate sensor 132 outside the casing 10, it is not only easy to install and maintain, but also avoids occupying the installation space in the casing 10, preventing groundwater and debris flowing into the casing 10 during the drilling process from contacting the sensor and causing loss of the sensor, thereby increasing the service life of the gas flow rate sensor 132. The flow rate monitoring box 131 can also provide physical protection for the gas flow rate sensor 132, reduce the interference of the external environment on the gas flow rate sensor 132, and ensure the stability and reliability of the measurement.

[0083] In some embodiments, see Figure 1 The detection device of the present application further includes a control module 14, which is respectively connected to the laser monitoring module 11, the shielding module 12 and the gas flow rate monitoring module 13. An exemplary control module 14 may include a PLC controller, a computer, a control center, and the like.

[0084] Accordingly, the control module 14 can be used to centrally control the laser monitoring module 11, the shielding module 12 and the gas flow rate monitoring module 13, so as to realize automatic control, unified management and coordinated operation of the entire detection equipment, making the operation easier and reducing the complexity of operation and the probability of error. The control module 14 can also execute precise control algorithms according to the data fed back by the sensors to realize high-precision control. The control module 14 can also integrate the measurement data of each sensor, perform unified data processing and analysis, and generate a comprehensive monitoring report. For example, through the control algorithm, the concentration of harmful gases at the bottom of the hole can be accurately calculated to generate a harmful gas hazard assessment report.

[0085] In some embodiments, see Figure 1 , Figure 2, a water tank 16 connected to the inner cavity of the casing 10 is provided below the casing 10; the bottom of the inner cavity of the water tank 16 has a water baffle 17 extending upward, and forms a water outlet cavity 161 and a sampling cavity 162 located on both sides of the water baffle 17, a water outlet pipe 18 connected to the water outlet cavity 161 is provided at the lower end of the water tank 16, and a sampling tube 19 connected to the sampling cavity 162 is provided at the lower end of the water tank 16. Exemplarily, the top of the water tank 16 is connected to the bottom of the casing 10, a flow meter 22 is provided on the water outlet pipe 18, and a sampling valve 23 is provided on the sampling tube 19.

[0086] Accordingly, the water tank 16 can be used to collect groundwater gushing out from the advanced borehole. The water tank 16 is divided into a water outlet chamber 161 and a sampling chamber 162 by a water baffle 17, which can prevent the mutual interference of the water outlet and sampling processes. The water outlet chamber 161 directly discharges water through the water outlet pipe 18 to ensure the smooth and efficient water outlet process. The flow rate of groundwater can be measured by the flow meter 22. The sampling chamber 162 is dedicated to sampling. By opening the sampling valve 23, sampling can be performed through the sampling tube 19 for analyzing the content of soluble harmful gases in groundwater.

[0087] See also Figure 1 , Figure 2 A filter 20 is horizontally arranged above the water baffle 17 in the water tank 16, and a slag discharge door 21 for opening and closing the chamber above the filter 20 is provided on the water tank 16. Exemplarily, the filter 20 can be a grille, a filter screen, and the like.

[0088] Accordingly, the filter element 20 can filter the drilling debris that enters the water tank 16 along with the groundwater, and prevent the drilling debris from entering the water outlet cavity 161 and the sampling cavity 162 and blocking the water outlet pipe 18 and the sampling pipe 19. The design of the debris discharge door 21 allows the chamber above the filter element 20 to be easily opened, which is convenient for regularly cleaning impurities and sediments on the filter element 20, reducing maintenance time and cost.

[0089] See also Figure 4 The embodiment of the present application also provides a method for detecting harmful gases in advance drilling of a tunnel, using a device for detecting harmful gases in advance drilling of a tunnel, the method comprising:

[0090] S1. Connect one end of the casing 10 to the orifice of the advance drilling hole 25.

[0091] For example, after drilling according to the advanced geological drilling design requirements, the casing 10 is placed on the drill pipe 15 and between the face 24 and the drilling rig. The right end of the casing 10 is connected to the orifice of the advanced borehole 25, and the left end of the casing 10 is connected to the drill pipe 15 through the flange assembly 26. In this way, the groundwater and harmful gases in the advanced borehole 25 can be guided into the casing 10. To simplify the view, Figure 4 The structure of the drilling rig is not shown.

[0092] S2, the laser monitoring module 11 emits laser to the bottom of the advance drilling hole 25 to obtain the concentration c1 of harmful gases from the laser monitoring module 11 to the bottom of the advance drilling hole 25.

[0093] Exemplarily, the laser gas sensor 111 is used to emit a laser to the bottom of the advance borehole 25 to obtain the concentration c1 of harmful gas from the laser gas sensor 111 to the bottom of the advance borehole 25, where the unit of c1 is ppm·m. Of course, the laser distance sensor 112 can also be used to emit a laser to the bottom of the advance borehole 25 to obtain the distance d1 from the laser distance sensor 112 to the bottom of the advance borehole 25, where the unit of d1 is m.

[0094] S3. After time t1, the shielding module 12 shields the laser in the casing 10, and the laser monitoring module 11 emits laser to the shielding module 12 to obtain the harmful gas concentration c2 and the distance d2 from the laser monitoring module 11 to the shielding module 12, and the gas flow rate monitoring module 13 monitors the flow rate v of the harmful gas in the casing 10.

[0095] Exemplarily, after time t1, the shielding module 12 shields the laser so that the laser cannot propagate to the bottom of the advanced borehole 25; the laser gas sensor 111 is used to emit laser to the shielding module 12, and the concentration c2 of harmful gas from the laser gas sensor 111 to the shielding module 12 is obtained, and the unit of c2 is ppm·m. The laser ranging sensor 112 is used to emit laser to the shielding module 12, and the distance d2 from the laser ranging sensor 112 to the shielding module 12 is obtained, and the unit of d2 is m. The gas flow rate sensor 132 is used to measure the flow rate v of harmful gas in the casing 10, and the unit of v is m / s.

[0096] S4. After time t2, the shielding module 12 releases the laser in the casing 10, and the laser monitoring module 11 emits laser to the bottom of the advance borehole 25 to obtain the concentration c3 of harmful gases from the laser monitoring module 11 to the bottom of the advance borehole 25.

[0097] Exemplarily, after time t2, the shielding module 12 is removed so that the laser can propagate to the bottom of the advance borehole 25; the laser gas sensor 111 is used to emit laser to the bottom of the advance borehole 25 to obtain the harmful gas concentration c3 from the laser gas sensor 111 to the bottom of the advance borehole 25, and the unit of c3 is ppm·m.

[0098] Since the shielding module 12 shields the laser periodically, the shielding period is set to T, and the unit of T is s, then t=t1+t2.

[0099] Since the harmful gas at the bottom of the advanced borehole 25 will flow along the borehole toward the hole mouth, the distance d3 of the harmful gas flowing in the hole within the T period can be calculated by the following formula: d3 = v × T. The unit of d3 is m.

[0100] Since the harmful gas in the advanced borehole 25 is constantly flowing, some of the harmful gas will flow to the outside of the casing 10, and the harmful gas concentration c2 from the laser monitoring module 11 to the shielding module 12 obtained by the laser gas sensor 111 can be regarded as the average concentration of the harmful gas flowing out of the casing 10, and the concentration c4 of the harmful gas flowing out of the casing 10 can be calculated by the following formula: c4 = (c2 / d2)·d3. Wherein, the unit of c4 is ppm·m.

[0101] S5. Calculate the concentration of harmful gases at the bottom of the advance borehole 25 according to the data obtained in steps S2, S3 and S4.

[0102] During the T period, harmful gases in the advance borehole 25 are both gushing out and replenished. By subtracting the harmful gas concentration obtained in step S3 from the harmful gas concentration obtained in step S1, and adding the harmful gas concentration gushing out of the casing 10, the average concentration of harmful gases gushing out of the newly revealed stratum at the bottom of the advance borehole 25 within a distance of d3 can be obtained.

[0103] The concentration C of harmful gases emerging from the formation newly revealed at the bottom of advance borehole 25 can be calculated according to the following formula: C = (c3-c1+c4) / d3 = [c3-c1+(vTc2 / d2)] / (vT). The unit of C is ppm.

[0104] The tunnel advance drilling harmful gas detection equipment and method provided in the embodiment of the present application can follow the drill rod 15 to detect the harmful gas concentration at the bottom of the advance drilling hole in real time and accurately, providing an accurate basis for the tunnel harmful gas hazard assessment.

[0105] Example:

[0106] Methane was revealed during the construction of a tunnel, and it was necessary to detect the methane concentration in the unconstructed section for tunnel gas registration and tunnel harmful gas hazard.

[0107] The tunnel advance drilling harmful gas detection equipment provided in the embodiment of the present application is used for detection. The shielding period T of the shielding module 12 is 2s, and the detected data are: c1=200ppm·m, c2=100ppm·m, c3=220ppm·m, v=0.1m / s, d2=0.2m.

[0108] The calculated methane gas concentration in the newly revealed stratum at the bottom of advance borehole 25 is:

[0109] C=[220-200+(0.1×2×100) / (0.1×2)] / (0.1×2)=600ppm.

[0110] If the traditional detection method is used, the average concentration of methane gas in the hole can only be measured to be 200ppm·m~220ppm·m. It can be seen that the traditional detection method is difficult to accurately detect the concentration of harmful gases at the bottom of the hole.

[0111] During the drilling process, groundwater and cooling water of the drilling rig enter the water tank 16 through the casing 10. The inspectors collect the groundwater and cooling water of the drilling rig through the sampling tube 19, and test the collected water samples to analyze the content of soluble harmful gases in the groundwater.

[0112] The above are only specific implementation methods of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed in the present application should be covered within the protection scope of the present application.

Claims

1. A tunnel advance drilling harmful gas detection device, characterized in that: The invention comprises a casing (10); a laser monitoring module (11) is provided on the casing (10), and the laser monitoring module (11) is used to emit laser light in the casing (10) along the axial direction of the casing (10), and to perform distance measurement and monitor the concentration of harmful gases; The sleeve (10) is provided with a shielding module (12), and the shielding module (12) is used to periodically shield the laser emitted by the laser monitoring module (11); the sleeve (10) is provided with a gas flow rate monitoring module (13), and the gas flow rate monitoring module (13) is used to monitor the flow rate of harmful gases in the sleeve (10).

2. The tunnel advance drilling harmful gas detection equipment according to claim 1 is characterized in that: The laser monitoring module (11) comprises a laser gas sensor (111), a laser distance sensor (112) and a reflection prism (113) which are arranged outside the casing (10); a laser hole (101) is provided on the tube wall of the casing (10); and the reflection prism (113) is used to reflect the laser emitted by the laser gas sensor (111) and the laser distance sensor (112) into the casing (10) through the laser hole (101) and propagate along the axial direction of the casing (10).

3. The tunnel advance drilling harmful gas detection equipment according to claim 2 is characterized in that: The laser monitoring module (11) further comprises a monitoring box (114) connected to the casing (10), and the laser gas sensor (111), the laser distance sensor (112) and the reflective prism (113) are arranged in the monitoring box (114).

4. The tunnel advance drilling harmful gas detection equipment according to claim 1 is characterized in that: The shielding module (12) comprises a driving member (121) arranged outside the sleeve (10) and a shielding member (122) connected to the driving member (121); a evasion hole (102) for evading the shielding member (122) is provided on the tube wall of the sleeve (10); the driving member (121) is used to drive the shielding member (122) to move and periodically shield the laser within the sleeve (10).

5. The tunnel advance drilling harmful gas detection equipment according to claim 1 is characterized in that: The gas flow rate monitoring module (13) comprises a flow rate monitoring box (131) arranged outside the sleeve (10) and a gas flow rate sensor (132) arranged inside the flow rate monitoring box (131); the flow rate monitoring box (131) is in communication with the inner cavity of the sleeve (10).

6. The tunnel advance drilling harmful gas detection equipment according to claim 1 is characterized in that: It also comprises a control module (14), wherein the control module (14) is respectively connected to the laser monitoring module (11), the shielding module (12) and the gas flow rate monitoring module (13).

7. The tunnel advance drilling harmful gas detection equipment according to claim 1 is characterized in that: The sleeve (10) is used to be sleeved on a drill rod (15), and the sleeve (10) can move on the drill rod (15) along the axial direction of the drill rod (15).

8. The tunnel advance drilling harmful gas detection equipment according to claim 1 is characterized in that: A water tank (16) connected to the inner cavity of the sleeve (10) is provided below the water tank (10); the bottom of the inner cavity of the water tank (16) has a water baffle (17) extending upward, and forms a water outlet cavity (161) and a sampling cavity (162) located on both sides of the water baffle (17); a water outlet pipe (18) connected to the water outlet cavity (161) is provided at the lower end of the water tank (16); and a sampling tube (19) connected to the sampling cavity (162) is provided at the lower end of the water tank (16).

9. The tunnel advance drilling harmful gas detection equipment according to claim 8 is characterized in that: A horizontally arranged filter element (20) is provided in the water tank (16) above the water baffle (17), and a slag discharge door (21) for opening and closing the chamber above the filter element (20) is provided on the water tank (16).

10. A method for detecting harmful gases in tunnel advance drilling, characterized in that: Using the tunnel advance drilling harmful gas detection device according to any one of claims 1 to 9, the method comprises: S1, connecting one end of the casing (10) to the orifice of the advance drilling hole (25); S2, the laser monitoring module (11) emits laser light to the bottom of the advance drilling hole (25), and obtains the concentration c1 of harmful gas from the laser monitoring module (11) to the bottom of the advance drilling hole (25); S3, after time t1, the shielding module (12) shields the laser in the casing (10), the laser monitoring module (11) emits laser light to the shielding module (12), obtains the concentration c2 of harmful gas from the laser monitoring module (11) to the shielding module (12) and the distance d2 from the laser monitoring module (11) to the shielding module (12), and the gas flow rate monitoring module (13) monitors the flow rate v of harmful gas in the casing (10); S4, after time t2, the shielding module (12) releases the laser in the casing (10), and the laser monitoring module (11) emits laser to the bottom of the advance borehole (25), and obtains the concentration c3 of harmful gases from the laser monitoring module (11) to the bottom of the advance borehole (25); S5. Calculate the concentration of harmful gases at the bottom of the advance borehole (25) based on the data obtained in steps S2, S3 and S4.

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