Geographic recording method for structural plane of surrounding rock of underground cavern

Abstract

The invention mainly relates to the technical field of underground engineering, and provides a geological logging method for a surrounding rock structural plane of an underground cavern in order to efficiently and conveniently carry out geological logging under a non-contact condition. Spatial position parameters of a plurality of feature points on a surrounding rock structural surface are measured remotely in a non-contact mode, precise three-dimensional coordinates and geological occurrence of the feature points of the structural surface are automatically calculated in combination with calibration coordinates of a current stake mark bottom plate center point measured on site, and three-dimensional information is precisely projected to a two-dimensional expanded geological catalog map. Therefore, efficient, safe and accurate geological logging of the surrounding rock of the underground cavern is realized.

Description

Technical Field

[0001] This invention relates to the field of underground engineering technology, and in particular to a method for geological logging of the surrounding rock structure of underground caverns. Background Technology

[0002] Rock mass structural surfaces are discontinuous surfaces with specific geometric shapes and mechanical properties formed under the influence of tectonic stress, engineering disturbances, etc., including faults, joints, bedding, and fissures. The properties of rock mass structural surfaces directly determine the mechanical properties and deformation and failure modes of the surrounding rock, affecting the stability of the surrounding rock of tunnels. Therefore, accurate recording of information on surrounding rock structural surfaces is crucial for obtaining first-hand engineering geological data, and has important reference value for underground tunnel excavation and support, optimization of hydraulic tunnel design, and safety and quality acceptance of concealed works construction.

[0003] In practice, the logging of surrounding rock structural surfaces still relies primarily on manual on-site measurements. This requires several geological engineers to work together, using compasses and measuring tapes to log the surrounding rock structural surfaces at close range, conducting extensive data measurements and recording. This is not only time-consuming and labor-intensive, but also difficult to conduct geological logging work at designated locations when tunnels have large spans, high safety risks, or during construction operations. In recent years, technologies such as 3D LiDAR scanning modeling and point cloud interpretation, and photo-based intelligent structural surface recognition algorithms based on trained machine learning models have been widely adopted. However, these technologies are limited by the tunnel environment, such as large amounts of dust from blasting, turbid exhaust fumes from mechanical equipment, shotcrete support in the surrounding rock, and unclear visibility. This makes it difficult to achieve complete structural surface identification and interpretation for large areas of surrounding rock, and the modeling cycle is long, prone to data omissions, and inefficient.

[0004] Therefore, there is an urgent need to integrate an efficient, convenient and reliable geological logging method that allows geological engineers to collect detailed structural surface data from a safe location within the tunnel without directly contacting the surrounding rock conditions. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a method for geological logging of the surrounding rock structure of underground caverns, with the aim of performing geological logging efficiently and conveniently under non-contact conditions.

[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0007] A method for geological logging of the surrounding rock structure of an underground cavern, the method comprising:

[0008] Step S1: Select a survey station inside the tunnel and measure the coordinates of the center point of the tunnel floor corresponding to the previous station number as the calibration point;

[0009] Step S2: Using the measuring station as a reference, obtain the spatial position parameters of multiple non-collinear feature points on the target surrounding rock structure surface relative to the measuring station;

[0010] Step S3: Calculate the three-dimensional coordinates of each feature point based on its spatial location parameters;

[0011] Step S4: Calculate the attitude information of the structural surface based on the obtained feature point coordinates;

[0012] Step S5: Based on the three-dimensional coordinates of the feature points and the cross-sectional dimensions of the cavern, project the three-dimensional surrounding rock structural plane attitude onto the two-dimensional unfolded planar logging card, and combine the calculated actual dip and dip angle of the structural plane to perform visual geological logging.

[0013] Furthermore, in step S1, the coordinates of the measurement station are obtained using an RTK positioning system.

[0014] Furthermore, in step S2, at least three non-collinear feature points are obtained in terms of their spatial location parameters.

[0015] Furthermore, the spatial location parameters mentioned in step S2 include the azimuth, slope distance, and elevation angle of the feature point relative to the measuring station.

[0016] Furthermore, the three-dimensional coordinates of the feature points in step S3 for:

[0017] ;

[0018] in, To measure the coordinates of the station, For the coordinates of the calibration point, The horizontal distance between the feature point and the measuring station. , The vertical distance between the feature point and the measuring station. , The pitch angle, It is a horizontal angle. To measure the height difference between the station and the center of the base plate at the corresponding station number.

[0019] Furthermore, step S4 includes:

[0020] Step S41: Fit the optimal plane using the least squares method based on the feature points;

[0021] Step S42: Calculate the relative dip and dip angle of the structural surface based on the normal vector of the optimal plane;

[0022] Step S43: Based on the tunnel orientation, convert the relative dip angle into the actual dip with the tunnel orientation as the reference, and calculate the actual direction based on the actual dip.

[0023] Furthermore, step S42 includes:

[0024] The least squares method is used to fit the feature points of each structural plane. The plane with the minimum sum of the squares of the vertical distances from all feature points to the plane to be fitted is taken as the best fitting plane. The normal vector of the best fitting plane is determined, and the relative position dip and tilt angle of the structural plane are calculated based on the normal vector of the best fitting plane.

[0025] Furthermore, the actual tendency is as follows: ,in As a relative tendency, the actual trend is .

[0026] Furthermore, step S5 includes:

[0027] Step S51: Based on the dimensions of the cavern, obtain the unfolded projection of the cavern with the cavern direction as the center;

[0028] Step S52: Determine the position of the feature point based on its projection. If At that time, feature points Located on a vertical wall, if At that time, feature points Located in the top arch; among them, For feature points The coordinate on the Y-axis, where D is the width of the cavern;

[0029] Step S53: If the feature point is located on the top arch, calculate the corresponding arc length based on the coordinates of the feature point. .

[0030] Furthermore, the arc length is calculated in step S53 as follows: , ,in, Rounded corners Where is the radius of the arch line. Let Z be the central angle of the arch, and Z be the vertical height of the wall. For feature points The coordinates on the z-axis.

[0031] The beneficial effects of this invention are as follows: By locating the measuring station, measuring the distance between the feature points on the structural surface and the measuring station, and performing position conversion with the calibration point, remote, rapid, and automated data acquisition and processing of the surrounding rock structural surface is realized in complex tunnel environments, significantly improving the safety and efficiency of logging operations. At the same time, based on the calibration of the bottom plate center point and spatial geometric calculation, high-precision acquisition of the structural surface coordinates and attitude is ensured, overcoming the limitations of traditional manual logging caused by construction interference, inaccessibility of dangerous areas, and large subjective errors. Finally, standardized and visualized geological logging results are generated, providing a reliable basis for engineering design and construction safety. Attached Figure Description

[0032] Figure 1 This is a flowchart illustrating the implementation of a geological logging method for the surrounding rock structure of an underground cavern according to the present invention.

[0033] Figure 2 This is a schematic diagram of a method for acquiring structural surface feature data using a portable laser rangefinder;

[0034] Figure 3 This is a two-dimensional unfolded schematic diagram of the surrounding rock wall of an underground cavern;

[0035] Figure 4 This is a schematic diagram of the arc-length spatial location within an underground cavern;

[0036] Figure 5 This is a schematic diagram showing the arc length position and geometric relationship in the cross-section of an underground cavern;

[0037] Figure 6 This is a schematic diagram of the geological logging results of the surrounding rock structure of an underground cavern in an example project. Detailed Implementation

[0038] The core of the technical solution adopted by this invention to solve the above-mentioned technical problems is: selecting a safe measuring station in the tunnel, measuring the spatial position parameters of multiple feature points on the surrounding rock structure surface remotely in a non-contact manner, and combining the calibration coordinates of the current station number bottom plate center point determined on site to automatically calculate the precise three-dimensional coordinates and geological occurrence of the feature points on the structure surface, and accurately projecting the three-dimensional information onto a two-dimensional geological logging map, thereby achieving efficient, safe and accurate geological logging of the surrounding rock of underground caverns.

[0039] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Taking a ventilation and safety tunnel of a pumped storage power station under construction as an example, the geological logging method for surrounding rock structural surfaces of the present invention is illustrated below. The specific implementation steps are as follows:

[0040] like Figure 1 As shown, the geological logging method for the surrounding rock structure of an underground cavern, as described in this invention, includes the following steps.

[0041] Step S1: Select a station point inside the tunnel and measure the coordinates of the center point of the tunnel floor corresponding to the previous station number as the calibration point.

[0042] The measurement station should be located in a safe area with a wide, unobstructed view, ensuring clear observation of the distribution characteristics of the surrounding rock structure, while avoiding areas prone to construction interference and rockfall risks. Secure the portable laser rangefinder to a tripod or stable support device, ensuring the equipment is level and stable to prevent data deviations caused by equipment movement during measurement. Start the RTK positioning system and perform equipment linkage calibration with the portable laser rangefinder to obtain the three-dimensional coordinates of the measurement station.

[0043] In this embodiment, the coordinates of the survey station of a certain project obtained based on the RTK positioning system are: Furthermore, based on the current location and mileage, measure the center point of the tunnel floor at the current station number. As a calibration point for global coordinates, it is used as a reference for subsequent conversion of structural surface feature point coordinates (the subsequent calculation process uses the engineering data in this embodiment to explain the subsequent steps).

[0044] Step S2: Using the measuring station as a reference, obtain the azimuth, slope distance, and pitch angle of multiple non-collinear feature points on the target surrounding rock structure surface relative to the measuring station.

[0045] Test site Using the laser rangefinder as a reference point, aim at at least three non-collinear feature points on the target structure surface in sequence (the more feature points, the higher the plane fitting accuracy), measure and record the spatial position parameters of each feature point, including azimuth, slant range and elevation angle.

[0046] During this process, it is necessary to identify the target surrounding rock structure surface in advance on-site using the naked eye or auxiliary tools (such as a flashlight) and to identify its key feature points such as edges and inflection points.

[0047] The azimuth measurement specifically includes: adjusting the aiming direction of the rangefinder, recording the azimuth of the feature point relative to the measuring station (the angle rotated clockwise with due north as the reference), accurate to 0.01°;

[0048] Distance measurement specifically includes: recording the slope distance between the measurement station and the feature point. (Accurate to 0.001m);

[0049] Pitch angle measurement specifically includes: recording the pitch angle when the rangefinder is aiming at a feature point. (The angle between the line connecting the measuring station and the feature point and the horizontal plane, with upward being positive and downward being negative), accurate to 0.01°.

[0050] The measured spatial location parameters are automatically transmitted and stored on the mobile terminal via Bluetooth or data cable, and bound according to the corresponding structural surface number to form the original dataset. The mobile terminal establishes a database for the received spatial location parameters in the format of "measurement station coordinates-calibration point coordinates-structural surface number-feature point number-azimuth-slope distance-elevation angle", and classifies and binds each structural surface data.

[0051] Step S3: Calculate the three-dimensional coordinates of each feature point based on the coordinates of the measuring station and the azimuth, slope distance and elevation angle of the feature point relative to the measuring station.

[0052] Based on the coordinates of the measurement station The coordinates of each feature point on the structural surface are generated through spatial geometric calculations, taking into account the angle and distance to the feature points. This embodiment demonstrates... The process of calculating the three-dimensional coordinates, and the process of calculating the coordinates of the remaining feature points are the same. The same applies, and will not be repeated here. Specifically, feature points The calculation process specifically includes:

[0053] Step 3.1: Obtain the test station and feature points horizontal distance and vertical distance .like Figure 2 As shown, the formula is derived from geometric relationships as follows:

[0054] , ;

[0055] In the formula, The straight-line distance between the feature point and the measuring station. The pitch angle; by , , and thus ;

[0056] Step 3.2: Obtain feature points horizontal angle :

[0057] ;

[0058] Step 3.3: Based on the measurement station and feature points horizontal distance and vertical distance and feature points horizontal angle Obtain feature point coordinates :

[0059] In this embodiment, the center coordinates of the tunnel floor slab at the station number are... The elevation differences between the survey station and the center of the base plate at the corresponding station number are 621101.0730, 3446229.5360, and 24.212. The feature points are calculated. The coordinates are:

[0060] .

[0061] In this embodiment, feature points are calculated in the same way. Feature points and feature points The coordinates are as follows: , , .

[0062] Step S4: Based on the obtained feature point coordinates, fit and determine the plane equation where the structural surface is located, and calculate the relative attitude parameters of the structural surface based on the normal vector of the plane equation.

[0063] Step 4.1: Use the least squares method to fit the feature points of each structural surface to obtain the best-fit plane:

[0064] , ;

[0065] in, Let represent the perpendicular distance from the i-th feature point to the plane to be fitted, and let a, b, c, and d be the coefficients of the plane equation. Let be the sum of squared errors. By adjusting coefficients a, b, and c, we obtain the plane where the sum of the squares of the perpendicular distances from all feature points to the plane to be fitted is minimized. This plane is the best-fit plane.

[0066] Step 4.2: The fitted plane can be represented by the general form of the plane equation:

[0067] ;

[0068] Its normal vector direction can be converted into the dip and dip angle of the surrounding rock structural plane, and the specific formula is as follows: The direction cosine of the structural plane's attitude is determined by the following formula, in which... Due to relative positional tendency, The angle is denoted by , and in the Cartesian coordinate system, the Y-axis points due north, the X-axis points due east, and the Z-axis points directly above the XY plane.

[0069] ;

[0070] Step 4.3: Calculate the relative position and attitude: Calculate the relative position and dip of the structural planes according to the formulas in Steps 4.1 and 4.2. ,inclination .

[0071] Step 4.4: Actual attitude of the surrounding rock structural plane: In actual geological logging, the tunnel direction is generally used as the X-axis pointing due east (90°) and the Y-axis pointing due north. Therefore, the actual position dips... The conversion is as follows:

[0072] ;

[0073] In the formula, the actual tendency is... The range of values ​​is Actual trend The direction perpendicular to the actual tendency, i.e., the actual trend. (If the actual direction) Then subtract 360°). This yields the actual dip direction of the surrounding rock structural plane. Actual trend ;

[0074] Step S5: Based on the three-dimensional coordinates of the feature points and the cross-sectional dimensions of the cavern, project the three-dimensional surrounding rock structural surface information onto the two-dimensional unfolded planar logging card, and combine it with the calculated actual dip and dip angle of the structural surface to perform visual geological logging.

[0075] The three-dimensional curved surface of the surrounding rock of the underground cavern is unfolded onto a two-dimensional plane, and the calculated information of the surrounding rock structure is projected onto a geological logging card to complete the visualized geological logging record.

[0076] Step 5.1: Obtain the dimensions of the cavern: In this embodiment, the vertical wall height of the ventilation and safety cavern is Z=5.80 m, the cavern width is D=7.20 m, the arch radius is R=4.64 m, and the central angle of the arch is... =106.3°, arch length S=8.60 m, height at the arch crown 7.60 m, with the tunnel orientation of 179.31° as the right axis, as follows Figure 3 As shown, with the vaulted ceiling as the center line, the left arch and left wall are projected above the center line of the unfolded diagram, while the right arch and right wall are projected below the center line. The specific unfolded plane is as follows: Figure 6 As shown;

[0077] Step 5.2: Obtain feature points Projection: 1) When At that time, feature points Located on a vertical wall, at this time and Projected onto a two-dimensional rock wall unfolded diagram; 2) When When describing feature points Located at the top arch, such as Figure 4 At this point, the arc length needs to be obtained. ,Will and A projection onto a two-dimensional rock wall.

[0078] Feature points in this embodiment of Feature points Located on a vertical wall, therefore and Projected on Figure 6 The two-dimensional rock wall unfolded diagram shown; feature points of Feature points Located at the top arch, the arc length needs to be obtained. ,Will and A projection onto a two-dimensional rock wall.

[0079] Step 5.3: Convert characteristic points of surrounding rock structural surfaces Figure 5 The corresponding arc length Arc length Represented as:

[0080] ;

[0081] According to the geometric relationships of a circular arc, the arc length... corresponding central angle It can be represented as:

[0082] ,or ;

[0083] At the same time, taking into account and Influence, central angle Take the average of the two formulas above; calculate the characteristic points. corresponding central angle Corresponding arc length .

[0084] Step 5.4, based on feature points ( , , , (…), project the corresponding surrounding rock structural surfaces, and verify the relationship between the corresponding station information and the structural surface number and attitude. In the same way, record other structural surfaces to complete the production of the geological logging map.

[0085] In this embodiment, all 30 structural surface traces of the surrounding rock were finally plotted on the geological logging card, and the completed logging results are as follows: Figure 6 As shown.

Claims

1. A method for geological logging of the surrounding rock structure of an underground cavern, characterized in that, The method includes: Step S1: Select a survey station inside the tunnel and measure the coordinates of the center point of the tunnel floor corresponding to the previous station number as the calibration point; Step S2: Using the measuring station as a reference, obtain the spatial position parameters of multiple non-collinear feature points on the target surrounding rock structure surface relative to the measuring station; Step S3: Calculate the three-dimensional coordinates of each feature point based on its spatial location parameters; Step S4: Calculate the attitude information of the structural surface based on the obtained feature point coordinates; Step S5: Based on the three-dimensional coordinates of the feature points and the cross-sectional dimensions of the cavern, project the three-dimensional surrounding rock structural plane attitude onto the two-dimensional unfolded planar logging card, and combine the calculated actual dip and dip angle of the structural plane to perform visual geological logging.

2. The geological logging method for the surrounding rock structure of an underground cavern as described in claim 1, characterized in that, In step S1, the coordinates of the measurement station are obtained using an RTK positioning system.

3. The method for geological logging of the surrounding rock structure of an underground cavern according to claim 1, characterized in that, In step S2, at least three non-collinear feature points must be obtained in terms of their spatial location parameters.

4. The geological logging method for the surrounding rock structure of an underground cavern according to claim 3, characterized in that, The spatial location parameters mentioned in step S2 include the azimuth, slope distance, and elevation angle of the feature point relative to the measuring station.

5. The geological logging method for the surrounding rock structure of an underground cavern according to claim 1, characterized in that, The three-dimensional coordinates of the feature points in step S3 for: ； in, To measure the coordinates of the station, For the coordinates of the calibration point, The horizontal distance between the feature point and the measuring station. , The vertical distance between the feature point and the measuring station. , The pitch angle, It is a horizontal angle. To measure the height difference between the station and the center of the base plate at the corresponding station number.

6. The method for geological logging of the surrounding rock structure of an underground cavern according to claim 1, characterized in that, Step S4 includes: Step S41: Fit the optimal plane using the least squares method based on the feature points; Step S42: Calculate the relative dip and dip angle of the structural surface based on the normal vector of the optimal plane; Step S43: Based on the tunnel orientation, convert the relative dip angle into the actual dip with the tunnel orientation as the reference, and calculate the actual direction based on the actual dip.

7. A method for geological logging of the surrounding rock structure of an underground cavern according to claim 6, characterized in that, Step S42 includes: The least squares method is used to fit the feature points of each structural plane. The plane with the minimum sum of the squares of the vertical distances from all feature points to the plane to be fitted is taken as the best fitting plane. The normal vector of the best fitting plane is determined, and the relative position dip and tilt angle of the structural plane are calculated based on the normal vector of the best fitting plane.

8. A method for geological logging of the surrounding rock structure of an underground cavern according to claim 7, characterized in that, The actual tendency is: ,in As a relative tendency, the actual trend is .

9. A method for geological logging of the surrounding rock structure of an underground cavern according to claim 1, characterized in that, Step S5 includes: Step S51: Based on the dimensions of the cavern, obtain the unfolded projection of the cavern with the cavern direction as the center; Step S52: Determine the position of the feature point based on its projection. If At that time, feature points Located on a vertical wall, if At that time, feature points Located in the top arch; among them, For feature points The coordinate on the Y-axis, where D is the width of the cavern; Step S53: If the feature point is located on the top arch, calculate the corresponding arc length based on the coordinates of the feature point. .

10. A method for geological logging of the surrounding rock structure of an underground cavern according to claim 9, characterized in that, The method for calculating the arc length in step S53 is as follows: , ,in, Rounded corners Where is the radius of the arch line. Let Z be the central angle of the arch, and Z be the vertical height of the wall. For feature points The coordinates on the z-axis.

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