Multi-purpose exploration adit layout method

Abstract

The present invention discloses a multi-purpose exploration adit layout method. It includes the following steps: Step 1: Drafting the position of the longitudinal tunnel section DOC and determining the positions of points D, O, and C on the adit axis; Step 2: Drafting the position of the transverse tunnel section CB and determining the position of point B on the adit axis; Step 3: Drafting the position of the oblique tunnel section BA and determining the position of point A on the adit axis; Step 4: After the positions of points D, O, C, B, and A have been determined in sequence, the layout of the exploration adit is determined; during actual adit construction, the adit construction excavation is carried out in the reverse order of points A, B, C, O, and D, and the oblique tunnel section BA, transverse tunnel section CB, and longitudinal tunnel section DOC are excavated in this order. The present invention not only realizes the multi-purpose of landslide investigation, sampling, testing, drainage, etc. in the adit, but also has the advantages of safe construction, cost savings, and shortened construction period.

Description

Technical Field

[0001] The present invention relates to the field of geotechnical engineering exploration and engineering geological exploration technology, and more specifically, it is a multi-purpose exploration flat tunnel layout method. More specifically, it is a layout method that uses three continuous tunnel sections in the oblique, horizontal and vertical directions as an exploration flat tunnel. Background Art

[0002] Once a landslide occurs, it often causes enormous losses to construction projects, industrial and agricultural production, and the loss of life and property, sometimes even leading to devastating disasters. To improve landslide prevention and mitigation capabilities, it is essential to understand the spatial morphology, material composition, and stability of landslides. Exploration is a crucial means of gaining a detailed understanding of landslide characteristics.

[0003] In engineering practice, drilling and adit tunneling are commonly used methods for landslide exploration. While drilling can detect the sliding surface to a certain extent, due to limitations in drilling and coring technology, it is still difficult to accurately locate and obtain in-situ samples. Adit tunneling is the most intuitive and reliable exploration method. Through adit tunnels in the landslide body, the scale of the landslide, the location of the sliding surface, the geological structure of the landslide body, and samples of various levels can be accurately revealed. In addition, in-situ testing can be conducted, providing scientific, first-hand data for landslide stability analysis and evaluation. Conventional exploration adit tunnels are arranged with the entrance located on the landslide body. The tunnel is excavated into the landslide body until it passes through the sliding surface and reaches a certain depth in the stable rock and soil. The surrounding rock of adit tunnels in the landslide body is extremely unstable. In particular, large landslides require long adit tunnels, slow excavation speeds, heavy support work, and high costs. Construction is prone to production safety accidents, and safety management pressures are high.

[0004] To ensure landslide stability, lowering the groundwater level through drainage is one of the most effective treatment methods. Conventional exploration tunnels are typically deployed during the survey phase, with only temporary support measures typically employed during construction. By the time the landslide treatment phase begins, the tunnels have often collapsed and cannot be used as drainage tunnels.

[0005] Therefore, it is necessary to develop a multi-purpose exploration tunnel layout method that can realize landslide investigation, sampling, testing, drainage and other multi-purpose functions in the tunnel, and has the advantages of safe construction, cost saving and shortened construction period. Summary of the Invention

[0006] The purpose of the present invention is to provide a multi-purpose exploration flat tunnel layout method, which adopts three continuous tunnel sections of oblique, horizontal and vertical directions as the layout method of an exploration flat tunnel. Only the longitudinal tunnel section is partially located in the landslide surrounding rock with poor stability, and the surrounding rock of the other tunnel sections is generally stable. This method can realize the multi-purpose of landslide exploration, sampling, testing, drainage, etc. in the flat tunnel, and has the advantages of safe construction, cost saving and shortened construction period.

[0007] In order to achieve the above-mentioned purpose, the technical scheme of the present invention is: a multi-purpose exploration flat tunnel arrangement method, which is characterized in that: the arranged multi-purpose exploration flat tunnel consists of three continuous tunnel sections, which can be divided into an oblique tunnel section BA, a transverse tunnel section CB, and a longitudinal tunnel section DOC according to the mutual relationship between the flat tunnel axis and the main axis of the landslide (the flat tunnel axis and the main axis of the landslide have three relative position relationships: the flat tunnel axis and the main axis of the landslide are obliquely intersected, which is an oblique tunnel section; the flat tunnel axis and the main axis of the landslide are perpendicular, which is a transverse tunnel section; the flat tunnel axis and the main axis of the landslide are nearly parallel or coincident, which is a longitudinal tunnel section); the axis of the oblique tunnel section BA is obliquely intersected with the main axis of the landslide, the axis of the transverse tunnel section CB is perpendicular to the main axis of the landslide, and the axis of the longitudinal tunnel section DOC is consistent with the main axis of the landslide; A, B, C, O, and D are all points on the flat tunnel axis (such as Figure 1 、 Figure 2 As shown, Figure 1 Based on the landslide plan geological map, Figure 2 (drawn based on the geological cross-section of the main axis of landslide sliding);

[0008] The specific method includes the following steps:

[0009] Step 1: Plan the location of the longitudinal tunnel section DOC and determine the locations of points D, O, and C on the main axis of the landslide;

[0010] Step 2: Plan the location of the transverse tunnel section CB and determine the location of point B on the horizontal tunnel axis;

[0011] Step 3: Plan the location of the oblique tunnel section BA and determine the location of point A on the horizontal tunnel axis;

[0012] Step 4: The positions of points D, O, C, B, and A are determined in sequence, which also determines the layout of the exploration adit. During the actual adit construction, the adit construction is carried out in the reverse order of points A, B, C, O, and D, and the oblique tunnel section BA, the horizontal tunnel section CB, and the longitudinal tunnel section DOC are excavated in this order.

[0013] Through the exploration flat tunnel, further landslide investigation, sliding surface sampling test, in-situ mechanical test and other work can be carried out, and the multi-purpose exploration flat tunnel can be transformed into a landslide drainage tunnel; during the flat tunnel construction process, safety protection should be strengthened.

[0014] In the above technical solution, the cross-sectional shape of the multi-purpose exploration flat tunnel is a gate-shaped or rectangular shape, with a diameter or height d of 2 to 3 meters, so as to facilitate excavation, testing, etc. in the flat tunnel;

[0015] The slope ratio i of a multi-purpose exploration adit is generally 2% to 5%, and the elevation gradually decreases from points D, O, C, B to point A; this is conducive to drainage and safe slag discharge; and prevents the problem that the bottom plate of the adit is too flat and not conducive to drainage when the slope ratio i is less than 2%, and the slope of the adit is too large and not conducive to safe slag discharge when the slope ratio i is greater than 5%.

[0016] In the above technical solution, in step 1, the method for determining the position of the longitudinal tunnel section is:

[0017] Assume that the connecting point of the landslide sliding section l1 and the anti-slip section l2 on the sliding surface is point O; draw a straight line through point O toward the outside of the landslide on the sliding surface, with a slope ratio of i. The intersection of this straight line and the groundwater level is point D. The groundwater level 7 is the bottom of the exploration tunnel (the bottom refers to the bottom of the exploration tunnel relative to the tunnel entrance); extend the straight line DO toward the inside of the landslide on the sliding surface until the thickness h of the overlying rock mass on the straight line DO is equal to 5 times the tunnel diameter d, that is, h = 5d. This end point is point C; the line connecting points D, O, and C is the axis of the longitudinal tunnel section.

[0018] The straight line DOC is the axis of the longitudinal tunnel section of the horizontal tunnel. The horizontal tunnel is arranged at the intersection of the landslide sliding section and the anti-slip section and is located below the groundwater level. It is conducive to fully draining the groundwater in the landslide sliding section, which can effectively reduce the sliding force and improve the stability of the landslide. The overlying rock thickness h refers to the distance between the horizontal tunnel top plate and the landslide sliding surface. The overlying rock thickness h at point C is 5 times the horizontal tunnel diameter d. The main purpose is to minimize the total length of the exploration horizontal tunnel to reduce the excavation workload while maintaining the stability of the surrounding rock during construction.

[0019] In the above technical solution, in step 2, the method for formulating the position of the transverse tunnel section is: the tunnel axis CB, point C has been determined in advance, and the formulation of the position of the transverse tunnel section is to determine the position of point B; a straight line is drawn through point C perpendicular to the main axis of the landslide, and the intersection of this straight line and the landslide boundary is point B; the line connecting point B and point C is the axis of the transverse tunnel section.

[0020] In the above technical solution, in step 3, the method for formulating the position of the oblique tunnel section is as follows: the tunnel axis BA and point B have been determined in advance, and the formulation of the oblique tunnel section position is to determine the position of point A; point A is located at the entrance of the multi-purpose exploration tunnel, on the outside of the landslide on the sliding surface, and as close as possible to the landslide boundary to shorten the total length of the exploration tunnel and reduce the excavation workload. The entrance is selected in a gully or groove area with good topographic and geological conditions, which is conducive to the smooth drainage of groundwater after leaving the exploration tunnel; the elevation of point A is related to the elevation of point D at the bottom of the tunnel, the slope ratio of the tunnel, and the total length of the tunnel. The elevation of point A is the difference between the elevation of point D and the product of the total length of the multi-purpose exploration tunnel and the slope ratio of the multi-purpose exploration tunnel; the line connecting point B and point A is the axis of the oblique tunnel section; the total length of the multi-purpose exploration tunnel is the sum of the lengths of the three tunnel sections, namely the oblique tunnel section BA, the transverse tunnel section CB, and the longitudinal tunnel section DOC, that is, the length of the broken line ABCOD; Figure 1 Based on the landslide plan geological map, Figure 2 Based on the geological profile of the main axis of the landslide, the total length of the horizontal tunnel can be Figure 1 The elevation of point D can be measured at Figure 2 On measurement.

[0021] The multi-purpose exploration adit layout method provided by the present invention has the following beneficial effects compared with conventional exploration adit layout methods:

[0022] (1) Safe construction, cost savings, and shortened construction period; the surrounding rock of the multi-purpose exploration flat tunnel is generally stable, reducing the safety hazards of underground construction; in the multi-purpose exploration flat tunnel, except for the local landslide surrounding rock of the longitudinal tunnel section, the rest of the tunnel section basically does not require support or adopts weak support, which can save a lot of costs; although the multi-purpose exploration flat tunnel is long, the surrounding rock geological conditions are good, the excavation speed is fast, and a lot of support time is not required, so the construction period can still be significantly shortened relatively speaking;

[0023] (2) It can realize multi-purpose functions; during the landslide exploration stage, landslide exploration, sampling, testing and other work can be carried out in the multi-purpose exploration flat tunnel. Because the multi-purpose exploration flat tunnel can maintain long-term stability, it can also be used as a drainage hole and appropriately modified during the landslide control stage to effectively lower the groundwater level, which is conducive to enhancing the stability of the landslide. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the plan layout of the multi-purpose exploration flat hole of the present invention.

[0025] Figure 2 This is the cross-sectional view of the flat tunnel for exploring the main axis of landslide sliding according to the present invention.

[0026] Figure 3 It is a flow chart of the arrangement method of the present invention.

[0027] exist Figure 1 In the figure, DOC represents the longitudinal section axis of the multi-purpose exploration flat tunnel, CB represents the transverse section axis of the multi-purpose exploration flat tunnel, and BA represents the inclined section axis of the multi-purpose exploration flat tunnel.

[0028] exist Figure 2 In the figure, l1 is the sliding section of the landslide, l2 is the anti-slip section of the landslide, d is the diameter or height of the exploration adit, and h is the thickness of the overlying rock mass of the exploration adit.

[0029] In the figure, 1-landslide body, 2-landslide boundary, 3-exploration adit, 4-exploration adit axis, 5-main axis of landslide sliding, 6-landslide sliding surface, 7-groundwater level line, 8-ground topography line. DETAILED DESCRIPTION

[0030] The following detailed description of the embodiments of the present invention is given in conjunction with the accompanying drawings, which do not limit the present invention but are merely examples. The description makes the advantages of the present invention clearer and easier to understand.

[0031] The present invention is now described in detail by taking the application of the present invention to the horizontal tunnel arrangement in the geological survey of Huanglashi landslide in a certain reservoir area as an example, which can also provide guidance for the application of the present invention to the horizontal tunnel arrangement in geotechnical engineering survey and engineering geological survey in other areas.

[0032] In this example, the Huanglashi landslide in a certain reservoir area has a round chair-shaped plan view, with a front elevation of approximately 2,139 meters and a rear elevation of approximately 2,294 meters, resulting in a height difference of approximately 155 meters. Landslide body 1 is 310 meters long along its longitudinal axis, 280 meters wide, with an average thickness of 45 meters and a volume of approximately 3.9 million cubic meters, making it a large landslide. Landslide body 1 is located between the landslide sliding surface 6 and the ground topographic line 8; the sliding surface 6 is below the groundwater level 7. Landslide body 1 is composed of crushed rock and soil, and the underlying bedrock is sandy slate and marble (medium-hard and hard rock). Preliminary geological survey results for the landslide were obtained during the pre-feasibility study phase, including a plan view geological map of the landslide and a geological profile of the main sliding axis of the landslide.

[0033] The multi-purpose exploration flat tunnel arranged by the multi-purpose exploration flat tunnel arrangement method of the present invention in this embodiment is composed of three continuous tunnel sections ( Figure 1 ), according to the relationship between the horizontal tunnel axis 4 and the main axis of the landslide 5, it can be divided into the oblique tunnel section BA, the transverse tunnel section CB, and the longitudinal tunnel section DOC; the axis of the oblique tunnel section BA is oblique to the main axis of the landslide (the angle is 45 degrees), the axis of the transverse tunnel section CB is orthogonal to the main axis of the landslide, and the axis of the longitudinal tunnel section DOC is consistent with (coincides with) the main axis of the landslide; A, B, C, O, and D are all points on the horizontal tunnel axis (such as Figure 1 、 Figure 2 As shown, Figure 1 Based on the landslide plan geological map, Figure 2 (Drawn based on the geological profile of the main axis of the landslide).

[0034] In this embodiment, the cross-section of the adit is a gate-shaped tunnel. To facilitate excavation and testing within the adit, the diameter d is 2.5 meters. To facilitate drainage and safe slag removal, the slope i is 3%, with the elevation gradually decreasing from D, O, C, B, to A.

[0035] This embodiment adopts the present invention to carry out multi-purpose exploration flat hole layout, including the following steps:

[0036] (1) Determination of the longitudinal tunnel section position, that is, determining the positions of points D, O, and C on the tunnel axis. On the sliding surface 6, the connection point of the landslide sliding section l1 and the anti-slip section l2 is point O; a straight line is drawn through point O in the outward direction of the slope with a slope ratio of 3%. The intersection of this straight line and the groundwater level line 7 is point D, which is also the bottom of the exploration tunnel; the straight line DO is extended in the inward direction of the slope until the thickness h of the overlying rock mass on the straight line is equal to 5 times the diameter d of the tunnel, that is, h = 5×2.5 = 12.5 meters, and the end point is point C; the straight line DOC is the axis of the longitudinal section of the tunnel. The tunnel is arranged at the intersection of the landslide sliding section and the anti-slip section and is located below the groundwater level, which is conducive to fully draining the groundwater in the landslide sliding section, which can effectively reduce the sliding force and improve the stability of the landslide; the overlying rock mass thickness h refers to the distance between the tunnel top plate and the landslide sliding surface. The overlying rock mass thickness h at point C is 5 times the diameter d of the tunnel. The main purpose is to minimize the total length of the exploration tunnel to reduce the excavation workload while maintaining the stability of the surrounding rock during construction.

[0037] (2) Determination of the location of the transverse tunnel section. The tunnel axis CB and point C have been determined in advance, that is, the location of point B is determined. A straight line is drawn through point C perpendicular to the main axis 5 of the landslide. The intersection of this line and the landslide boundary 2 is point B.

[0038] (3) The location of the oblique tunnel section is planned. The tunnel axis BA and point B have been determined in advance, that is, the location of point A is determined. Point A is the entrance to the multi-purpose exploration tunnel. Considering that there is a gully about 30m east of the landslide boundary, the entrance is selected on the gully slope on the west side of the gully, where the bedrock is exposed and the terrain and geological conditions are good. After the tunnel is transformed into a drainage tunnel, the water in the tunnel can be directly discharged into the gully; there is usually no water at the bottom of the gully. Before the tunnel is constructed, a water guide wall is built to prevent the gully water from interfering with the tunnel construction during the rainy season. The elevation of point A is the difference between the elevation of point D and the product of the total length of the tunnel and the slope ratio of the tunnel. The elevation of point D at the bottom of the tunnel is Figure 2 The upper measurement is 2184 meters. The total length of the horizontal tunnel (the length of the broken line ABCOD) can be found in Figure 1 The upper measurement is 413 meters (the sum of the oblique tunnel section length of 161 meters, the horizontal tunnel section length of 142 meters, and the longitudinal tunnel section length of 110 meters). The slope ratio i is 3%. Therefore, the elevation of point A at the entrance to the tunnel = 2184-413×3% = 2171.61 meters, which is rounded to 2172 meters.

[0039] (4) Through the above process, the positions of points D, O, C, B, and A were determined, which also determined the layout of the exploration adit. During the actual adit construction, excavation was carried out in the reverse order of points A, B, C, O, and D, and the inclined tunnel section, horizontal tunnel section, and longitudinal tunnel section were excavated in turn.

[0040] Conclusion: This embodiment adopts the method of the present invention to arrange multi-purpose exploration flat tunnels, of which the overall stable bedrock tunnel sections account for 91.8% (this embodiment adopts the multi-purpose exploration flat tunnel described in the present invention. Except for the local tunnel sections that are unstable in the landslide body (such as the OD section), most of the other tunnel sections are located in the stable rock and soil body below the landslide body; it overcomes the defects of the existing conventional landslide exploration flat tunnels that most tunnel sections are within the landslide body, the surrounding rock is unstable, and strong support is required). The unstable landslide body tunnel sections account for only 8.2%, and the excavation time is 83 days; it overcomes the defects of the existing technology of using conventional flat tunnels, entering the tunnel from the landslide body and excavating into the slope. Because the surrounding rock stability is very poor and strong support is required, strong support is required while excavating, the progress is very slow, the support cost is high, it is labor-intensive and time-consuming, and there are great safety hazards.

[0041] During the feasibility study and investigation, this embodiment arranged an exploration flat tunnel and carried out landslide investigation, sampling, testing and other work in the tunnel. Later, the flat tunnel was appropriately modified and used as a drainage tunnel with good results. This overcomes the problem of the conventional flat tunnel used in the prior art, in which the flat tunnel is excavated during the early investigation period. When the landslide is controlled in the later period, due to the long time interval, even the flat tunnel with support will basically collapse and cannot be used as a drainage tunnel to play a drainage role. As a result, there is a defect that the flat tunnel cannot be used for multiple purposes such as landslide investigation, sampling, testing, and drainage.

[0042] The multi-purpose exploration tunnel layout method provided by this invention has been successfully tested in engineering geological surveys at a hydropower station and in a special geological survey of the Huanglashi landslide in a reservoir area. The results show that using this method to arrange landslide exploration tunnels, only a portion of the longitudinal tunnel section is located within the unstable landslide surrounding rock, while the surrounding rock of the remaining tunnel sections is generally stable. This method not only enables the tunnel to be used for multiple purposes such as landslide investigation, sampling, testing, and drainage, but also offers the advantages of safe construction, cost savings, and shortened construction schedules.

[0043] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

[0044] Other parts not described belong to the prior art.

Claims

1. A multi-purpose exploration adit arrangement method, characterized by: The arranged multi-purpose exploration flat tunnel consists of three continuous tunnel sections, which are divided into the oblique tunnel section BA, the transverse tunnel section CB, and the longitudinal tunnel section DOC according to the relationship between the flat tunnel axis (4) and the main axis of the landslide (5); the axis of the oblique tunnel section BA is oblique to the main axis of the landslide (5), the axis of the transverse tunnel section CB is orthogonal to the main axis of the landslide (5), and the axis of the longitudinal tunnel section DOC is consistent with the main axis of the landslide (5); A, B, C, O, and D are all points on the flat tunnel axis (4); The specific method includes the following steps: Step 1: Plan the location of the longitudinal tunnel section DOC and determine the locations of points D, O, and C on the main axis of the landslide (5); Step 2: Plan the location of the transverse tunnel section CB and determine the location of point B on the horizontal tunnel axis (4); Step 3: Plan the position of the oblique tunnel section BA and determine the position of point A on the horizontal tunnel axis (4); Step 4: Carry out horizontal tunnel construction in the order of points A, B, C, O, and D, and excavate the oblique tunnel section BA, the horizontal tunnel section CB, and the longitudinal tunnel section DOC in that order; Through the exploration adit, further landslide investigation, sliding surface sampling test, in-situ mechanical test and other work are carried out, and the multi-purpose exploration adit is transformed into a landslide drainage tunnel; The slope ratio i of the multi-purpose exploration adit is 2% to 5%, and the elevation gradually decreases from points D, O, C, B to point A; In step 1, the method for determining the location of the longitudinal tunnel section is as follows: Assume that the connecting point of the sliding section and the anti-slip section of the landslide on the sliding surface (6) is point O; draw a straight line through point O toward the outside of the landslide on the sliding surface (6), with a slope ratio of i. The intersection of this straight line and the groundwater level line (7) is point D, and the groundwater level line (7) is the bottom of the multi-purpose exploration tunnel; extend the straight line DO toward the inside of the landslide on the sliding surface (6) to point C. The thickness of the overlying rock mass at point C is equal to 5 times the diameter of the tunnel; the line connecting points D, O, and C is the axis of the longitudinal tunnel section of the tunnel.

2. The multi-purpose exploration adit arrangement method according to claim 1, characterized in that: In step 2, the method for determining the position of the transverse tunnel section is as follows: draw a straight line through point C perpendicular to the main axis of the landslide (5), and the intersection of this straight line and the landslide boundary (2) is point B; the line connecting point B and point C is the axis of the transverse tunnel section.

3. The multi-purpose exploration adit arrangement method according to claim 2, characterized in that: In step 3, the method for determining the position of the oblique tunnel section is as follows: point A is located at the entrance of the multi-purpose exploration flat tunnel, outside the landslide of the sliding surface (6); the elevation of point A is the difference between the elevation of point D and the product of the total length of the multi-purpose exploration flat tunnel and the slope ratio of the multi-purpose exploration flat tunnel; the line connecting point B and point A is the axis of the oblique tunnel section; the total length of the multi-purpose exploration flat tunnel is the sum of the lengths of the three tunnel sections, namely the oblique tunnel section BA, the transverse tunnel section CB, and the longitudinal tunnel section DOC, that is, the length of the broken line ABCOD.

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