A method and device for releasing stress of rock burst in horizontal hole over long distance

Abstract

The present invention provides a horizontal hole long-distance rockburst stress release method and device, including: using horizontal directional drilling to test the ground stress in front of the tunnel face to obtain the ground stress of the test area; setting a first threshold, judging whether it is a high ground stress area according to the relationship between the ground stress of the test area and the first threshold; for the high ground stress area, judging the rockburst level of the high ground stress area according to the ground stress of the high ground stress area; and releasing stress in the corresponding high ground stress area according to the rockburst level. The present invention can take into account both ground stress testing and stress release, and can achieve stress release in a long-distance high ground stress area.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel construction, and in particular to a method and device for releasing long-distance rock burst stress in a horizontal hole. Background Art

[0002] At present, my country has adopted a variety of effective strategies to deal with rock bursts, such as stress relief, improving the properties of surrounding rocks, strengthening construction support, cutting grooves to release stress in areas where rock bursts occur, and taking necessary protection for personnel and equipment during construction in rock burst areas. During tunnel excavation, the ground stress and geological conditions in the long distance area in front of the face are very important for tunnel excavation projects. By mastering the ground stress and geological conditions, the safety of tunnel excavation projects can be guaranteed, and the premise for further controlling the deformation of high ground stress tunnel surrounding rocks can be provided.

[0003] However, in the existing methods, for example, the advance drilling method is used to control the deformation of high-ground stress soft rock tunnels, but it is impossible to take into account both long-distance ground stress testing and stress release in high-ground stress areas at the same time, and there is no technology for simultaneous long-distance advanced geological forecasting. This makes the construction operation of tunnel excavation projects complicated (long-distance ground stress testing and stress release in high-ground stress areas, long-distance advanced geological forecasting are performed separately), resulting in low stress release efficiency and low construction efficiency. Summary of the invention

[0004] In view of the defects in the prior art, the purpose of the present invention is to provide a horizontal hole long-distance rockburst stress release method, which can release stress in remote high-ground stress areas while taking into account ground stress testing and stress release effects.

[0005] A first aspect of the present invention provides a method for relieving long-distance rockburst stress in a horizontal hole, comprising:

[0006] The ground stress test in front of the tunnel face is carried out by horizontal directional drilling to obtain the ground stress in the test area;

[0007] Setting a first threshold, and judging whether the test area is a high ground stress area according to the relationship between the ground stress of the test area and the first threshold;

[0008] For the high geostress area, judging the rockburst level of the high geostress area according to the geostress of the high geostress area;

[0009] Stress release is performed on the corresponding high ground stress area according to the rock burst level.

[0010] Optionally, a horizontal directional drill is used to conduct a ground stress test in front of the tunnel face to obtain the ground stress in the test area, including:

[0011] A horizontal directional drill is used, and a ground stress test module is installed on the horizontal directional drill;

[0012] The drill bit of the horizontal directional drill is used to drill a horizontal hole to reach a designated test area;

[0013] The geostress testing module is used to perform geostress testing in the test area to obtain the geostress in the test area.

[0014] Optionally, the horizontal directional drilling further includes a guidance and control module, and the guidance and control module is used to plan a drilling route of the drill bit and control the drill bit to reach a designated test area according to the drilling route.

[0015] Optionally, the guidance and control module controls the drill bit of the horizontal directional drill to drill along a line parallel to the central axis of the tunnel, and controls the drilling route of the drill bit to gradually approach the central axis of the tunnel, and finally controls the drilling route of the drill bit to coincide with the central axis of the tunnel and reach the designated test area.

[0016] Optionally, the geostress testing module further includes an in-hole geostress testing submodule;

[0017] Forming one or more ground stress test holes on the side wall of the borehole of the horizontal directional drill;

[0018] The in-hole in-situ stress testing submodule is extended into the in-situ stress testing hole to test the magnitude and direction of the in-situ stress at the in-situ stress testing hole.

[0019] Optionally, judging the rockburst grade of the high geostress area according to the geostress of the high geostress area includes:

[0020] Select the rockburst grade criterion;

[0021] Calculating a criterion value corresponding to the ground stress in the high ground stress area according to the rockburst grade criterion;

[0022] According to a set rockburst grade criterion threshold, determining the rockburst grade of the high ground stress area corresponding to the criterion value;

[0023] The rockburst levels include slight rockburst, moderate rockburst and severe rockburst.

[0024] Optionally, the step of releasing stress on the corresponding high ground stress area according to the rockburst level includes:

[0025] For minor rock bursts: use horizontal directional drilling to advance the drilling and use branch holes for stress relief;

[0026] For moderate rock bursts: Use horizontal directional drilling to advance holes around the tunnel face and use branch holes for stress relief;

[0027] For severe rock bursts: take preventive measures and use horizontal directional drilling to advance drill holes around and on the tunnel face, and use branch holes for stress relief.

[0028] Optionally, the method also includes: advanced geological prediction, the horizontal directional drill is provided with a guidance and control module; while the horizontal directional drill is used to conduct geostress testing on the tunnel, the drill bit of the horizontal directional drill is controlled by the guidance and control module to perform coring on one or more designated points in the test area, thereby realizing long-distance advanced geological prediction ahead of the tunnel construction.

[0029] A second aspect of the present invention provides a horizontal hole long distance rock burst stress release device, comprising:

[0030] Geostress testing unit: includes a horizontal directional drill capable of drilling horizontally over long distances, used to perform geostress testing on tunnels and obtain the geostress in the test area;

[0031] A first judgment unit: setting a first threshold value, and judging whether the test area is a high ground stress area according to the relationship between the ground stress of the test area and the first threshold value;

[0032] A second judgment unit: for the high ground stress area, judging the rock burst level of the high ground stress area according to the ground stress of the high ground stress area;

[0033] Stress release unit: performs stress release on the corresponding high ground stress area according to the rock burst level.

[0034] Optionally, the device also includes: an advanced geological prediction unit. While the geostress testing unit uses horizontal directional drilling to perform geostress testing on the tunnel, the advanced geological prediction unit controls the drill bit of the horizontal directional drill through the guidance and control module to perform coring on one or more designated points in the test area, thereby realizing long-distance advanced geological prediction ahead of tunnel construction.

[0035] Compared with the prior art, the embodiments of the present invention have at least one of the following beneficial effects:

[0036] The present invention simultaneously adopts ground stress test, high ground stress area and judgment of corresponding rock burst level, and can carry out ground stress test on the long distance area in front of the tunnel face during tunnel excavation. When it is collected that there is a high ground stress area in front of the tunnel face, stress release operation can be carried out in this area to prevent rock burst.

[0037] The present invention can carry out long-distance advanced geological prediction through horizontal directional drilling and its guidance and control module, with little impact on tunnel construction. For example, it can achieve advanced geological prediction of more than 1,000 meters, and correspondingly, it can also achieve ground stress testing and stress release operations at a distance of more than 1,000 meters. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0039] Figure 1 This is a flow chart of a method for releasing stress of a horizontal hole over a long distance rock burst in one embodiment of the present invention;

[0040] Figure 2 A schematic diagram of a working method of a geostress test in an embodiment of the present invention;

[0041] Figure 3 A schematic diagram of detailed rockburst levels and stress release in one embodiment of the present invention;

[0042] Figure 4 A schematic diagram of providing branch holes for stress release in one embodiment of the present invention;

[0043] Figure 5 It is a structural block diagram of a long-distance rockburst stress release device for a horizontal hole in one embodiment of the present invention. DETAILED DESCRIPTION

[0044] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0045] In the description of the present invention, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0046] The prior art cannot release stress in a high-stress area at a long distance, and cannot take into account both the ground stress test and the stress release effect. To address this problem, a method and device for releasing stress in a horizontal hole over a long distance of rock burst are proposed in an embodiment of the present invention.

[0047] Figure 1 The present invention is a flowchart of a method for releasing long-distance rockburst stress in a horizontal hole according to an embodiment of the present invention.

[0048] Reference Figure 1 As shown, the horizontal hole long-distance rockburst stress release method in this embodiment includes:

[0049] S100, uses horizontal directional drilling to test the ground stress in front of the tunnel face and obtains the ground stress in the test area;

[0050] S200, setting a first threshold, and judging whether the test area is a high ground stress area according to the relationship between the ground stress of the test area and the first threshold;

[0051] S300, for a high geostress area, judging the rockburst level of the high geostress area according to the geostress of the high geostress area;

[0052] S400: stress release is performed on the corresponding high ground stress area according to the rock burst level.

[0053] This embodiment simultaneously adopts geostress testing and determines the high geostress area and the rockburst level corresponding to each high geostress area according to the test results, so as to take into account both the geostress testing and stress release effect of the high geostress area, and perform stress release operation in the area to prevent rockburst. The whole method is simple to operate, and several technical problems can be solved through one horizontal directional drilling operation, which greatly improves the efficiency of tunnel construction and stress release.

[0054] In order to better complete the geostress test and obtain the geostress in the test area, in some possible implementations, a geostress test module is installed on the horizontal directional drill. Specifically, it may include:

[0055] S101, uses horizontal directional drilling, and the horizontal directional drilling is equipped with a ground stress test module;

[0056] S102, drilling a horizontal hole with a horizontal directional drill to reach a designated test area;

[0057] S103, performing a geostress test in the test area using a geostress test module to obtain the geostress in the test area.

[0058] In this embodiment, because a horizontal directional drill is used to perform the above-mentioned geostress test operation, the test of a specified distance can be completed by splicing the drill rod of the horizontal directional drill, including a long distance such as a geostress test of more than 1000 meters.

[0059] In order to enable the horizontal directional drill to reach the designated test area to complete the geostress test, in some possible implementations, a guide control module is also installed on the drill bit of the horizontal directional drill, and the guide control module is used to plan the drilling route of the drill bit and control the drill bit to reach the designated test area according to the drilling route. Preferably, in the specific drilling process, the guide control module controls the drill bit of the horizontal directional drill to drill along a line parallel to the central axis of the tunnel according to the drilling route, and controls the drilling route of the drill bit to gradually approach the central axis of the tunnel, and finally controls the drilling route of the drill bit to coincide with the central axis of the tunnel and reach the designated test area. The geostress obtained in this way coincides with the central axis of the tunnel, which can more accurately evaluate the geostress test results ahead of the tunnel construction, and further determine the specific stress release method based on the geostress.

[0060] Reference Figure 2 As shown, in some possible implementations, the geostress testing module further includes a borehole geostress testing submodule, which may specifically include:

[0061] S1011, forming one or more ground stress test holes on the side wall of the borehole of the horizontal directional drill;

[0062] S1012, extending the in-hole in-situ stress test submodule into the in-situ stress test hole to test the magnitude and direction of the in-situ stress at the in-situ stress test hole.

[0063] During the tunnel excavation process, the geostress data of the test area can be obtained by performing a geostress test through the above-mentioned operation of this embodiment; after obtaining the test results of the geostress test holes at multiple set positions on the tunnel excavation route, the distribution and change law of the geostress in the test area on the tunnel excavation route can be obtained by processing and analyzing the data of the multiple test holes.

[0064] In some embodiments, the geostress testing module and the in-hole geostress testing submodule may select existing technologies, such as borehole strain gauges, borehole rigid strain gauges, borehole piezomagnetic stress gauges, etc. For example, the borehole strain gauge is installed on the drill bit. During the test, the borehole rigid strain gauge is in close contact with the surrounding rock. By measuring the readings of the strain gauge or displacement gauge, the strain change around the borehole can be obtained. Since the geostress will cause the rock to produce strain, the magnitude and direction of the geostress can be inferred by measuring these strain data. For another example, the borehole strain gauge is installed on the drill bit and reaches the geostress test hole. The borehole strain gauge can use a flexible strain gauge so that it can adapt to the deformation of the stratum and measure the geostress more accurately. For another example, the borehole piezomagnetic stress gauge is composed of one or more magnetic elements. When the local stress acts on the rock, the rock will deform, which will cause the magnetism of the magnetic element to change. By measuring these magnetic changes, the magnitude and direction of the geostress can be inferred.

[0065] Reference Figure 3 As shown, after obtaining the specific ground stress magnitude of the designated test area, in order to achieve rockburst stress release, in this embodiment, it is necessary to further determine the rockburst level of the high ground stress area according to the ground stress of the high ground stress area. Generally speaking, the rockburst level can be divided into three levels according to the ground stress magnitude, namely, slight rockburst, strong rockburst, and moderate rockburst. Specifically, the rockburst level of the high ground stress area can be determined according to the following steps:

[0066] S201, select rockburst grade criterion;

[0067] S202, calculating a criterion value corresponding to the ground stress in the high ground stress area according to the rock burst grade criterion;

[0068] S203, according to the set rockburst grade criterion threshold, determine the rockburst grade of the high ground stress area corresponding to the criterion value obtained in S202. The rockburst grade can be divided into slight rockburst, moderate rockburst and severe rockburst according to the impact on the construction.

[0069] However, different criteria have different specific methods for determining the rockburst level. For example, in some embodiments, the rockburst level can be determined according to the following settings based on the ground stress:

[0070] The second threshold is set as the rockburst level criterion threshold, and the high ground stress area where the criterion value corresponding to the ground stress is between the first threshold and the second threshold is judged as a slight rockburst, or a slight rockburst and a moderate rockburst level; the high ground stress area where the criterion value corresponding to the ground stress is less than the second threshold is judged as a severe rockburst.

[0071] Of course, in other embodiments, a third threshold value may be further set, and a high ground stress area with a criterion value corresponding to the ground stress between the second threshold value and the third threshold value is judged as a moderate rock burst. Correspondingly, a high ground stress area with a criterion value corresponding to the ground stress less than the third threshold value is judged as a severe rock burst.

[0072] Specifically, the judgment of rock burst level can refer to a variety of criteria, and the rock burst level judgment threshold can be set according to the specific rock mass, actual engineering conditions and selected criteria. The judgment value corresponding to the ground stress is determined according to different criteria, such as using ground stress and rock compressive strength calculation to determine the corresponding judgment value.

[0073] For example, let σ c is the uniaxial compressive strength of rock, σ max is the maximum principal stress, σ θThe maximum tangential stress can be used to determine the rockburst grade according to the following criteria, including but not limited to the Barton criterion, the Engineering Rock Mass Classification Standard (GB50218-2014), and the Soviet Union HA. Dolchaninov criterion. The parameters used in each criterion are also different.

[0074] For example, for the Barton criterion, according to the criterion, the criterion value corresponding to the in-situ stress is σ c / σ max , the first threshold and the second threshold are 5 and 2.5 respectively, then:

[0075] When σ c / σ max >5, judged as no rock burst;

[0076] When 2.5≤σ c / σ max ≥5, judged as slight rockburst or moderate rockburst;

[0077] When σ c / σ max <2.5, it is judged as a strong rock burst.

[0078] For example, for the engineering rock mass classification standard (GB50218-2014), according to the criterion:

[0079] When σ c / σ max >6, judged as no rock burst;

[0080] When 3≤σ c / σ max ≥6, judged as slight rockburst or moderate rockburst;

[0081] When σ c / σ max <3, judged to be a strong rock burst.

[0082] For example, for the Soviet HA. Dolchaninov criterion, we have:

[0083] When σ θ / σ max ≤0.3, it is judged that there is no rock burst;

[0084] When σ θ / σ max =0.3~0.8, it is judged as slight rock burst or moderate rock burst;

[0085] When σ θ / σ max >0.8, it is judged as a strong rock burst.

[0086] The above are some examples of rock burst judgment. In actual applications, you can choose which judgment to use according to the situation.

[0087] In addition, there may be other classifications for rock burst levels, such as extremely strong rock burst, which has a greater impact than strong rock burst. These can be set according to actual needs.

[0088] Based on the rockburst level determined above, stress release is performed on the high ground stress area corresponding to the rockburst level, and different stress release methods can be used for different rockburst levels. Specifically, in a specific implementation, the following method can be referred to:

[0089] For minor rock bursts: use horizontal directional drilling to advance the drilling and use branch holes for stress relief;

[0090] For moderate rock bursts: Use horizontal directional drilling to advance holes around the tunnel face and use branch holes for stress relief;

[0091] For severe rock bursts: take preventive measures and use horizontal directional drilling to advance drill holes around and on the tunnel face, and use branch holes for stress relief.

[0092] In the above stress release method, the specific branch holes can be in various situations, such as multiple holes distributed in a triangle, or in a circle, or of course, in a pentagon, without limitation. Figure 4 In other embodiments, other stress release methods may also be used, and are not limited to the above embodiments.

[0093] In a possible implementation, in addition to judging the rockburst level by the criterion value and threshold value corresponding to the ground stress, other features can be further combined to judge the rockburst level. The more features there are, the more accurate the rockburst level and subsequent stress release will be. Specifically, these features include but are not limited to: one or more of sound features, movement features, rock block morphology features, fracture features, occurrence location, time-effect features, impact depth, and the magnitude of the harmful impact on the project. These features can be obtained through geological forecasting or obtained after further analysis based on the obtained data.

[0094] Exemplarily, in one embodiment, the rockburst level and corresponding stress release measures may be determined by referring to the following table:

[0095]

[0096] In the above table, R b is the saturated uniaxial compressive strength of rock (MPa), σ m is the maximum principal stress.

[0097] In other possible implementations, a horizontal directional drill is provided with a guide control module, and while performing stress testing, advanced geological prediction can also be achieved, that is: while using the horizontal directional drill to test the geostress of the tunnel, the guide control module is used to control the drill bit of the horizontal directional drill to take coring at one or more designated points in the test area, so as to achieve long-distance advanced geological prediction ahead of the tunnel construction. Preferably, an intelligent sensing device, such as a three-dimensional in-hole television, etc., is further provided on the drill bit or geostress test module of the horizontal directional drill to realize the perception of specific data and realize advanced geological prediction. These devices can also be used to collect and obtain various features in the above table.

[0098] This embodiment combines ground stress testing and advanced geological prediction to conduct comprehensive testing of the geological conditions in the long distance area ahead of the tunnel face to avoid possible geological risks during construction and provide a reliable basis for tunnel design and construction.

[0099] Based on the same technical concept, in another embodiment of the present invention, a horizontal hole long-distance rockburst stress release device is also provided, which is used to implement the above-mentioned horizontal hole long-distance rockburst stress release method. Figure 5 As shown, in this embodiment, the horizontal hole long-distance rock burst stress release device includes:

[0100] Geostress testing unit: includes a horizontal directional drill capable of drilling horizontally over long distances, used to perform geostress testing on tunnels and obtain the geostress in the test area;

[0101] A first judgment unit: setting a first threshold value, and judging whether the test area is a high ground stress area according to the relationship between the ground stress of the test area and the first threshold value;

[0102] The second judgment unit: for a high ground stress area, judging the rock burst level of the high ground stress area according to the ground stress of the high ground stress area;

[0103] Stress release unit: stress release is performed on the corresponding high ground stress area according to the rock burst level.

[0104] In a possible implementation, the horizontal hole long-distance rockburst stress release device also includes: an advanced geological prediction unit. While the ground stress testing unit uses a horizontal directional drill to perform a ground stress test on the tunnel, the advanced geological prediction unit controls the drill bit of the horizontal directional drill through the guidance and control module to take coring at one or more designated points in the test area, thereby realizing a long-distance advanced geological prediction ahead of the tunnel construction.

[0105] The units of the horizontal hole long-distance rockburst stress release device mentioned above in this embodiment correspond to the steps in the horizontal hole long-distance rockburst stress release method. If the specific implementation technology is not described in detail, the implementation process can be referred to the steps in the above method, which will not be repeated here.

[0106] All the drawings in the above embodiments are only for the convenience of explaining the technical content of the present invention; the technical features such as the numbers, positions of components, relationships between components and sizes of components used to constitute the optimal implementation method do not constitute a limitation on the technical solution itself, but should extend to the entire field covered by this technical field.

[0107] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various modifications or variations within the scope of the claims, which does not affect the essence of the present invention. The above preferred features can be used in any combination without conflicting with each other.

Claims

1. A horizontal hole long distance rock burst stress release method, It is characterized in that include: The ground stress test in front of the tunnel face is carried out by horizontal directional drilling to obtain the ground stress in the test area; Setting a first threshold, and judging whether the test area is a high ground stress area according to the relationship between the ground stress of the test area and the first threshold; For the high geostress area, judging the rockburst level of the high geostress area according to the geostress of the high geostress area; Performing stress relief on the corresponding high ground stress area according to the rock burst level; The method of using horizontal directional drilling to test the ground stress in front of the tunnel face to obtain the ground stress in the test area includes: A horizontal directional drill is used, and a ground stress test module is installed on the horizontal directional drill; The drill bit of the horizontal directional drill is used to drill a horizontal hole in front of the tunnel face to reach the designated test area; Performing a geostress test in the test area using the geostress test module to obtain the geostress in the test area; The step of releasing stress in the corresponding high ground stress area according to the rock burst level includes: For minor rock bursts: use horizontal directional drilling to advance the drilling and use branch holes for stress relief; For moderate rock bursts: Use horizontal directional drilling to advance holes around the tunnel face and use branch holes for stress relief; For severe rock bursts: take preventive measures and use horizontal directional drilling to advance holes around and on the tunnel face, and use branch holes for stress relief; The method also includes: advanced geological prediction, the horizontal directional drill is provided with a guidance and control module; while the horizontal directional drill is used to perform a ground stress test in front of the tunnel face, the drill bit of the horizontal directional drill is controlled by the guidance and control module to perform coring at one or more designated points in the test area, thereby realizing a long-distance advanced geological prediction in front of the tunnel construction.

2. The horizontal hole long distance rock burst stress release method according to claim 1, It is characterized in that The horizontal directional drilling comprises a guidance and control module, and the guidance and control module is used to plan a drilling route of the drill bit and control the drill bit to reach a designated test area according to the drilling route.

3. The horizontal hole long distance rock burst stress release method according to claim 2, It is characterized in that The guidance and control module controls the drill bit of the horizontal directional drill to drill along a line parallel to the central axis of the tunnel, and controls the drilling route of the drill bit to gradually approach the central axis of the tunnel, and finally controls the drilling route of the drill bit to coincide with the central axis of the tunnel and reach the designated test area.

4. The horizontal hole long distance rock burst stress release method according to claim 1, It is characterized in that The geostress testing module also includes a borehole geostress testing submodule; Forming one or more ground stress test holes on the side wall of the borehole of the horizontal directional drill; The in-hole in-situ stress testing submodule is extended into the in-situ stress testing hole to test the magnitude and direction of the in-situ stress at the in-situ stress testing hole.

5. The horizontal hole long distance rock burst stress release method according to claim 1, It is characterized in that The step of judging the rockburst level of the high geostress area according to the geostress of the high geostress area includes: Select the rockburst grade criterion; Calculating a criterion value corresponding to the ground stress in the high ground stress area according to the rockburst grade criterion; According to a set rockburst grade criterion threshold, determining the rockburst grade of the high ground stress area corresponding to the criterion value; The rockburst levels include slight rockburst, moderate rockburst and severe rockburst.

6. A horizontal hole long distance rock burst stress release device, used to implement the horizontal hole long distance rock burst stress release method according to any one of claims 1 to 5, It is characterized in that include: Geostress testing unit: includes a horizontal directional drill capable of drilling horizontally over long distances, used to perform geostress testing on tunnels and obtain the geostress in the test area; A first judgment unit: setting a first threshold value, and judging whether the test area is a high ground stress area according to the relationship between the ground stress of the test area and the first threshold value; A second judgment unit: for the high ground stress area, judging the rock burst level of the high ground stress area according to the ground stress of the high ground stress area; Stress release unit: performing stress release on the corresponding high ground stress area according to the rock burst level; The device also includes: an advanced geological prediction unit. While the ground stress testing unit uses a horizontal directional drill to perform a ground stress test in front of the tunnel face, the advanced geological prediction unit controls the drill bit of the horizontal directional drill through a guidance and control module to perform coring at one or more designated points in the test area, thereby realizing a long-distance advanced geological prediction ahead of the tunnel construction.

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