A large-fall geological disaster body deep settlement monitoring method

Abstract

The application discloses a kind of big fall geologic hazard body deep settlement monitoring method, belong to settlement monitoring technical field, can solve the low-precision problem of big fall geologic hazard body deep settlement monitoring result irregular fluctuation, cycle slip.The method comprises the following steps: S1, setting reference point at the periphery of geologic hazard body, and setting multiple monitoring points in the hole of geologic hazard body;S2, determine the triangular height difference of hole monitoring point relative to reference point, and according to the triangular height difference, determine the first level difference of the deepest monitoring point relative to hole monitoring point;S3, according to the triangular height difference and the first level difference, determine the height difference change of the deepest monitoring point in the current monitoring period;S4, determine the allowable error of the deepest monitoring point, and determine the elevation of all monitoring points in the current monitoring period according to the height difference change and the allowable error.The application is used for the deep settlement monitoring of big fall geologic hazard body.

Description

Technical Field

[0001] This invention relates to a method for monitoring deep subsidence of geological disaster bodies with large elevation differences, belonging to the field of subsidence monitoring technology. Background Technology

[0002] Currently, geological disasters are frequent in some major river basins, posing significant challenges to the safety of people's livelihoods and property, as well as engineering construction. In particular, geological disasters with large elevation differences in deep mountain and canyon areas have a more severe impact on the basin due to their complex geographical environment and the uncertainty of their timing, frequency, and severity. To better predict, manage, and prevent geological disasters, a series of explorations have been conducted on some large-elevation geological disaster bodies. Based on this, a series of monitoring points and devices have been deployed. Through continuous monitoring, the aim is to understand the trend and scale of the movement of large-elevation geological disaster bodies, analyze their displacement patterns, and ultimately achieve early warning and forecasting, as well as formulate effective protective measures.

[0003] For settlement monitoring inside tunnels of geological hazards with large elevation differences, leveling is usually used. However, due to the special topographical limitations of such geological hazards, the monitoring benchmark is often selected on the periphery of the geological hazard or even on the opposite bank. In the process of high-precision settlement monitoring, the benchmark is usually first transferred to the tunnel entrance using trigonometric leveling, and then leveling is used to collect data from each monitoring point inside the tunnel through the transfer point at the tunnel entrance. After data comparison and analysis, the reliability of this method depends heavily on the accuracy of the trigonometric leveling section from which the benchmark is transferred to the tunnel entrance. Neither the work efficiency nor the accuracy of the results is ideal, which has seriously restricted the relevant prediction and assessment work of geological hazards. Summary of the Invention

[0004] This invention provides a method for monitoring deep subsidence of geological disaster bodies with large elevation differences. It can solve the problems of irregular fluctuations and cycle slips in monitoring results caused by the instability of large elevation differences and long spans in trigonometric leveling during the monitoring process of deep subsidence of geological disaster bodies with large elevation differences.

[0005] This invention provides a method for monitoring deep subsidence of geological disaster bodies with large elevation differences, the method comprising:

[0006] S1. Set up benchmark points around the geological hazard body and set up multiple monitoring points inside the geological hazard body cave; the monitoring points include the cave entrance monitoring point, the deepest monitoring point inside the cave, and the remaining monitoring points;

[0007] S2. Determine the triangular elevation difference between the monitoring point at the tunnel entrance and the benchmark point, and based on the triangular elevation difference, determine the first leveling elevation difference between the monitoring point at the deepest point and the monitoring point at the tunnel entrance.

[0008] S3. Based on the triangular elevation difference and the first leveling elevation difference, determine the elevation difference change of the deepest monitoring point during the current monitoring period;

[0009] S4. Determine the allowable error of the deepest monitoring point, and determine the elevation of all monitoring points in the current monitoring cycle based on the elevation difference change and the allowable error.

[0010] Optionally, S3 specifically includes:

[0011] Based on the triangular elevation difference and the first leveling elevation difference, determine the total elevation difference of the deepest monitoring point relative to the benchmark point in each monitoring cycle;

[0012] The change in elevation of the deepest monitoring point in the current monitoring period is determined based on the total elevation difference of the deepest monitoring point in the current monitoring period and the total elevation difference in the previous monitoring period.

[0013] Optionally, based on the triangular elevation difference and the first leveling elevation difference, the total elevation difference between the deepest monitoring point and the benchmark point in each monitoring cycle is determined, specifically as follows:

[0014] The sum of the triangular elevation difference within each monitoring cycle and the first level elevation difference of the corresponding monitoring cycle is obtained as the total elevation difference of the deepest monitoring point relative to the benchmark point in the corresponding monitoring cycle.

[0015] Optionally, the change in elevation difference of the deepest monitoring point within the current monitoring period is determined based on the total elevation difference of the deepest monitoring point within the current monitoring period and the total elevation difference within the previous monitoring period, specifically as follows:

[0016] The difference between the total elevation difference of the deepest monitoring point in the current monitoring period and the total elevation difference in the previous monitoring period is obtained, and is used as the elevation difference change of the deepest monitoring point in the current monitoring period.

[0017] Optionally, the allowable error for determining the deepest monitoring point in S4 specifically includes:

[0018] Determine the triangulation error transmitted from the benchmark point to the monitoring point at the tunnel entrance, and determine the leveling error transmitted from the monitoring point at the tunnel entrance to the monitoring point at the deepest point;

[0019] Based on the trigonometric error and the leveling error, the allowable error of the deepest monitoring point is determined.

[0020] Optionally, in step S4, determining the elevation of all monitoring points within the current monitoring period based on the elevation difference change and the allowable error specifically involves:

[0021] When the change in elevation difference is less than or equal to the allowable error, the elevation of each monitoring point in the current monitoring period is determined based on the elevation of the deepest monitoring point in the previous monitoring period and the second level elevation difference of each monitoring point relative to the deepest monitoring point in the current monitoring period.

[0022] When the change in elevation difference is greater than the allowable error, the elevation of each monitoring point in the current monitoring period is determined based on the elevation of the benchmark point, the trigonometric elevation difference, and the third leveling difference of each monitoring point relative to the portal monitoring point in the current monitoring period.

[0023] Optionally, the elevation of each monitoring point in the current monitoring period is determined based on the elevation of the deepest monitoring point in the previous monitoring period and the second level difference between each monitoring point and the deepest monitoring point in the current monitoring period, specifically as follows:

[0024] The elevation of the deepest monitoring point in the previous monitoring period and the sum of the second level difference between each monitoring point and the deepest monitoring point in the current monitoring period are obtained as the elevation of the corresponding monitoring point in the current monitoring period.

[0025] Optionally, the elevation of each monitoring point in the current monitoring period is determined based on the elevation of the benchmark point, the trigonometric elevation difference, and the third leveling difference between each monitoring point and the portal monitoring point in the current monitoring period. Specifically, this includes:

[0026] The elevation of the benchmark point, the trigonometric elevation difference, and the sum of the third leveling difference of each monitoring point relative to the portal monitoring point within the current monitoring period are obtained, and used as the elevation of the corresponding monitoring point within the current monitoring period.

[0027] Optionally, the allowable error of the deepest monitoring point is determined based on the trigonometric error and the leveling error, specifically including:

[0028] Calculate the sum of the squares of the trigonometric errors and the squares of the leveling errors, and take the square root of the sum as the allowable error for the deepest monitoring point.

[0029] The beneficial effects that this invention can produce include:

[0030] This invention provides a method for monitoring deep subsidence in large-dip geological disaster bodies. The elevation is transferred from a benchmark point to a monitoring point at the tunnel entrance using trigonometric leveling. Then, leveling is used to observe the elevation from the tunnel entrance monitoring point to the deepest monitoring point inside the tunnel. Based on this, the elevation difference between the deepest monitoring point and the benchmark point is calculated and compared with the previous observation data. If the change in elevation difference is within the allowable error range (a combination of trigonometric and leveling errors), the deepest monitoring point is considered stable within the current monitoring cycle, and the elevation is not corrected; the previous results are used. Simultaneously, the results from other monitoring points inside the tunnel are calculated based on this deepest monitoring point for leveling transfer, ensuring that the results from other monitoring points in each period are based solely on leveling measurements, avoiding the instability of trigonometric leveling transfer affecting the final monitoring results. This invention has practical value and broad application prospects, and is suitable for high-precision monitoring of deep subsidence in large-dip geological disaster bodies. Attached Figure Description

[0031] Figure 1 A flowchart of a method for monitoring deep subsidence of geological disaster bodies with large elevation differences, provided in an embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram of a settlement monitoring operation scenario provided in an embodiment of the present invention;

[0033] Figure 3 This invention provides a cumulative settlement trend chart for 10 periods of monitoring points at the tunnel entrance, calculated from the deepest monitoring point as the starting point;

[0034] Figure 4 The cumulative settlement trend of the tunnel entrance monitoring point over 10 periods is calculated using the traditional monitoring method provided in this embodiment of the invention. Detailed Implementation

[0035] The present invention will now be described in detail with reference to the embodiments, but the present invention is not limited to these embodiments.

[0036] This invention provides a method for monitoring deep subsidence of geological disaster bodies with large elevation differences, such as... Figure 1 As shown, the method includes:

[0037] S1. Set up benchmark points around the geological hazard body and set up multiple monitoring points inside the geological hazard body cave; the monitoring points include the cave entrance monitoring point, the deepest monitoring point inside the cave, and the other monitoring points.

[0038] For monitoring deep settlement of large-dip geological hazards, leveling is typically used for elevation measurement to ensure high-precision monitoring of elevation settlement. The selection of benchmark points for vertical displacement monitoring within tunnels of large-dip geological hazards usually follows these principles: First, the benchmark point must not be located within the geological hazard area to ensure its stability; second, it must not be located on the opposite bank of the geological hazard. Considering the steep slope of large-dip geological hazards, the long-term presence of landslides and debris, and the frequency and cycle of monitoring, a geometric leveling method connecting the benchmark point on the opposite bank to the leveling point inside the tunnel is not feasible. Therefore, the benchmark point for vertical displacement monitoring within the tunnel is usually selected on the opposite bank of the geological hazard.

[0039] S2. Determine the triangular elevation difference between the monitoring point at the tunnel entrance and the benchmark point, and based on the triangular elevation difference, determine the first leveling elevation difference between the monitoring point at the deepest point and the monitoring point at the tunnel entrance.

[0040] Specifically, the trigonometric leveling method is used to determine the trigonometric elevation difference between the monitoring point at the tunnel entrance and the benchmark point, and based on the trigonometric elevation difference, the leveling method is used to determine the first leveling elevation difference between the monitoring point at the deepest point and the monitoring point at the tunnel entrance.

[0041] The trigonometric leveling from the benchmark point on the opposite bank to the monitoring point at the tunnel entrance is usually performed using a third-order trigonometric leveling method with single-trip double-measurement, and the trigonometric elevation difference is calculated. The calculation formula is as follows:

[0042] ;

[0043] In the formula, Atmospheric refractive index; The average radius of curvature of the Earth is taken as 6,371,572 m. The horizontal distance (m) between station A and station B; The zenith distance (°) between station A and station B; , The instrument height (m) at stations A and B; , The prism heights for stations A and B.

[0044] Leveling inside horizontal tunnels is usually done using second-order leveling, with equipment including electronic levels or optical levels.

[0045] S3. Based on the triangular elevation difference and the first level elevation difference, determine the elevation difference change of the deepest monitoring point during the current monitoring period.

[0046] Specifically, it includes:

[0047] (1) Based on the triangular elevation difference and the first leveling elevation difference, determine the total elevation difference between the deepest monitoring point and the benchmark point in each monitoring cycle;

[0048] Specifically: the sum of the triangular elevation difference within each monitoring cycle and the first level elevation difference of the corresponding monitoring cycle is obtained as the total elevation difference of the deepest monitoring point relative to the benchmark point in the corresponding monitoring cycle.

[0049] The elevation difference between the deepest monitoring point inside the tunnel and the external monitoring benchmark point is calculated using conventional methods during the current monitoring period (i.e., this period), as shown in the following formula:

[0050] .

[0051] (2) Determine the change in elevation of the deepest monitoring point in the current monitoring period based on the total elevation difference of the deepest monitoring point in the current monitoring period and the total elevation difference in the previous monitoring period.

[0052] Specifically: the difference between the total elevation difference of the deepest monitoring point in the current monitoring period (i.e., this period) and the total elevation difference in the previous monitoring period (i.e., the previous period) is obtained as the change in elevation difference of the deepest monitoring point in the current monitoring period.

[0053] The formula for calculating the change in elevation at the deepest monitoring point during the current monitoring period (i.e., this period) is as follows:

[0054] .

[0055] S4. Determine the allowable error for the deepest monitoring point, and determine the elevation of all monitoring points within the current monitoring cycle based on the elevation difference change and the allowable error.

[0056] The allowable error for determining the deepest monitoring point specifically includes:

[0057] (1) Determine the triangular error from the benchmark point to the monitoring point at the tunnel entrance, and determine the leveling error from the monitoring point at the tunnel entrance to the monitoring point at the deepest point;

[0058] The formula for calculating the allowable error (i.e., trigonometric error) of a single-trip double-measurement of third-order trigonometric leveling is as follows:

[0059] ;

[0060] In the formula, D is the length of the measuring side (in km).

[0061] When calculating the permissible error of a leveling section inside a tunnel, since it is currently not possible to achieve a closed route or loop in leveling within the tunnel, the discrepancy between the forward and backward measurements of second-order surveying is used to determine the permissible error (i.e., leveling error) of this section of leveling. The specific calculation is as follows:

[0062] ;

[0063] In the formula, L is the length of the route or section (in km), and L less than 100m is counted as 100m.

[0064] (2) Determine the allowable error of the deepest monitoring point based on the trigonometric error and the leveling error.

[0065] Specifically, according to the law of error propagation, the sum of the squares of the trigonometric errors and the squares of the leveling errors is calculated, and the square root of the sum is taken as the allowable error of the deepest monitoring point.

[0066] According to the conventional third-order trigonometric leveling transfer and second-order leveling surveying inside the tunnel, the formula for calculating the allowable error of the monitoring point at the deepest point inside the tunnel is as follows:

[0067] .

[0068] Specifically, the elevation of all monitoring points within the current monitoring period is determined based on the elevation difference change and allowable error, as follows:

[0069] (1) When the change in elevation difference is less than or equal to the allowable error, the elevation of each monitoring point in the current monitoring period is determined based on the elevation of the deepest monitoring point in the previous monitoring period and the second level elevation difference of each monitoring point relative to the deepest monitoring point in the current monitoring period.

[0070] Specifically, when the change in elevation difference is less than or equal to the allowable error, the elevation of the deepest monitoring point in the previous monitoring cycle and the sum of the second level elevation difference of each monitoring point relative to the deepest monitoring point in the current monitoring cycle are obtained as the elevation of the corresponding monitoring point in the current monitoring cycle.

[0071] like If the monitoring point at the deepest point in the cave is stable during the current monitoring period, then this monitoring point will be used as the starting point for other monitoring points in the cave, i.e.:

[0072] ;

[0073] In the formula, For monitoring points Elevation during the current monitoring period; The elevation of the deepest monitoring point during the previous monitoring period. For monitoring points The difference in level between the deepest monitoring point and the current monitoring period.

[0074] (2) When the change in elevation difference is greater than the allowable error, the elevation of each monitoring point in the current monitoring period shall be determined based on the elevation of the benchmark point, the trigonometric elevation difference and the third level elevation difference of each monitoring point relative to the monitoring point at the tunnel entrance in the current monitoring period.

[0075] Specifically, when the change in elevation difference exceeds the allowable error, the elevation of the benchmark point, the trigonometric elevation difference, and the sum of the third leveling difference of each monitoring point relative to the tunnel entrance monitoring point within the current monitoring period are obtained, and used as the elevation of the corresponding monitoring point within the current monitoring period.

[0076] like If the monitoring point at the deepest point inside the cave is unstable during the current monitoring period, it cannot be used as the starting point for other monitoring points inside the cave. The results of all monitoring points inside the cave will still be obtained using a combination of trigonometric leveling outside the cave and leveling inside the cave, i.e.:

[0077] ;

[0078] In the formula, For monitoring points Elevation during the current monitoring period; The elevation of the benchmark point; It is a triangular elevation difference; This refers to the difference in elevation between the monitoring point and the monitoring point at the tunnel entrance during the current monitoring period.

[0079] The existing monitoring scheme is as follows: First, the elevation is transferred from the benchmark point to the tunnel entrance using trigonometric leveling. Then, leveling is used to conduct observations at each monitoring point from the tunnel entrance to the tunnel interior. The specific connection diagram is as follows. Figure 2 As shown. Based on Figure 2 The method described above was used to monitor vertical displacement within the tunnel for multiple periods. It was found that the elevations of the monitoring points within the tunnel fluctuated significantly and irregularly in each period. However, the elevation differences between the monitoring points within the tunnel remained almost unchanged, especially the relative elevation differences between several monitoring points near the depths of the tunnel, which were almost identical across multiple monitoring periods (within 1 mm). Statistical comparative analysis revealed that the data fluctuations were mainly due to random errors caused by the trigonometric leveling measurements transferred from the benchmark point to the tunnel entrance. Since the vertical displacement monitoring within the tunnel was obtained by combining a trigonometric leveling measurement with a leveling measurement, each trigonometric leveling measurement introduced a larger error fluctuation compared to leveling. The elevations of the monitoring points within the tunnel all relied on the elevation differences measured by this trigonometric leveling measurement for absolute elevation calculation. This resulted in the apparent lack of significant change in the elevation differences between the monitoring points, while the absolute elevation fluctuated due to the random error of the first trigonometric leveling measurement, creating the illusion of overall data fluctuation.

[0080] To address this situation, the present invention employs the following method: Elevation is transferred from the benchmark point to the tunnel entrance using trigonometric leveling. Then, leveling is used to continue observations from the tunnel entrance to the deepest monitoring point within the tunnel. Based on this, the elevation difference between the deepest monitoring point and the benchmark point is calculated and compared with the previous observation data. If the difference is within the allowable error range (a combination of trigonometric leveling and leveling errors), the deepest monitoring point is considered stable during this observation period, and its elevation is not corrected; the previous results are used. Simultaneously, the leveling calculations for other monitoring points within the tunnel are based on this deepest monitoring point. After verification that the deepest point within the tunnel is stable, this method ensures that the results for other monitoring points are transferred solely based on leveling elevations, without trigonometric leveling participating in the elevation calculation. This eliminates the random errors introduced by trigonometric leveling and ensures the overall stability of the monitoring data.

[0081] The following example uses a specific deformation monitoring project in Tibet. The side length D of the trigonometric leveling distance is 850m, and the leveling route from the trigonometric leveling transfer point to the monitoring point at the deepest point inside the cave is 160m. Based on the above formula, the allowable error for this section is:

[0082] .

[0083] After comparing the monitoring data of 10 monitoring cycles (each monitoring cycle is 1 month), it was found that the change in elevation difference of the monitoring point at the deepest point in the tunnel in each period was within ±3mm, which is less than the allowable error of ±7.5mm. Therefore, it was determined that the monitoring point at the deepest point in the tunnel was stable in the 10 monitoring cycles. The initial value of this point can be used as the reference point, and the settlement of each monitoring point in each period can be calculated by leveling elevation difference.

[0084] Figure 3 To obtain the settlement trend map of the outermost monitoring point at the entrance of tunnel No. 3 over 10 periods using this method, and simultaneously, to obtain the settlement trend map of the outermost point at the entrance over 10 periods using traditional monitoring methods, combining trigonometric leveling and tunnel entrance leveling, as shown below. Figure 4 As shown.

[0085] From the above Figure 3 It can be seen that after optimizing the starting point scheme using this method, the cumulative settlement of a certain monitoring point over the past 10 monitoring periods shows a clear trend, and the data does not exhibit any cycle-slipping or repetitive phenomena; while Figure 4 Traditional elevation monitoring methods can obtain cumulative settlement monitoring data for a certain monitoring point over the past 10 periods. Although the overall settlement magnitude and trend can be seen, some data in the middle will show a bouncing phenomenon. This is because the error range of the trigonometric leveling transfer section exceeds the settlement change range of the point itself.

[0086] This invention analyzes and summarizes existing elevation transfer methods and the specific conditions of deep displacement within horizontal tunnels. It proposes a method to transform the monitoring starting point from an external reference point of the geological hazard to a stable point within the monitoring body. An algorithm is used to determine the stability of the starting point within the geological hazard body before subsequent monitoring calculations and analyses are performed. Through continuous monitoring engineering practices on multiple large-drop geological hazard bodies, this method can significantly improve the accuracy of deep settlement monitoring for large-drop geological hazard bodies, and its application prospects are broad.

[0087] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for monitoring deep subsidence in a geological hazard body with a large elevation difference, characterized in that, The method includes: S1. Set up benchmark points around the geological hazard body and set up multiple monitoring points inside the geological hazard body cave; the monitoring points include the cave entrance monitoring point, the deepest monitoring point inside the cave, and the remaining monitoring points; S2. Determine the triangular elevation difference between the monitoring point at the tunnel entrance and the benchmark point, and based on the triangular elevation difference, determine the first leveling elevation difference between the monitoring point at the deepest point and the monitoring point at the tunnel entrance. S3. Based on the triangular elevation difference and the first leveling elevation difference, determine the elevation difference change of the deepest monitoring point during the current monitoring period; S4. Determine the trigonometric error transmitted from the benchmark point to the tunnel entrance monitoring point, and determine the leveling error transmitted from the tunnel entrance monitoring point to the deepest monitoring point; calculate the sum of the squares of the trigonometric error and the squares of the leveling error, and take the square root of the sum as the allowable error of the deepest monitoring point. When the change in elevation difference is less than or equal to the allowable error, determine the elevation of each monitoring point in the current monitoring period based on the elevation of the deepest monitoring point in the previous monitoring period and the second leveling difference of each monitoring point relative to the deepest monitoring point in the current monitoring period; when the change in elevation difference is greater than the allowable error, determine the elevation of each monitoring point in the current monitoring period based on the elevation of the benchmark point, the trigonometric elevation difference, and the third leveling difference of each monitoring point relative to the tunnel entrance monitoring point in the current monitoring period.

2. The method according to claim 1, characterized in that, S3 specifically includes: Based on the triangular elevation difference and the first leveling elevation difference, determine the total elevation difference of the deepest monitoring point relative to the benchmark point in each monitoring cycle; The change in elevation of the deepest monitoring point in the current monitoring period is determined based on the total elevation difference of the deepest monitoring point in the current monitoring period and the total elevation difference in the previous monitoring period.

3. The method according to claim 2, characterized in that, Based on the triangular elevation difference and the first leveling elevation difference, the total elevation difference between the deepest monitoring point and the benchmark point in each monitoring cycle is determined, specifically as follows: The sum of the triangular elevation difference within each monitoring cycle and the first level elevation difference of the corresponding monitoring cycle is obtained as the total elevation difference of the deepest monitoring point relative to the benchmark point in the corresponding monitoring cycle.

4. The method according to claim 2, characterized in that, Based on the total elevation difference of the deepest monitoring point in the current monitoring period and the total elevation difference in the previous monitoring period, the change in elevation difference of the deepest monitoring point in the current monitoring period is determined, specifically as follows: The difference between the total elevation difference of the deepest monitoring point in the current monitoring period and the total elevation difference in the previous monitoring period is obtained, and is used as the elevation difference change of the deepest monitoring point in the current monitoring period.

5. The method according to claim 1, characterized in that, Based on the elevation of the deepest monitoring point in the previous monitoring cycle and the second level difference between each monitoring point and the deepest monitoring point in the current monitoring cycle, the elevation of each monitoring point in the current monitoring cycle is determined as follows: The elevation of the deepest monitoring point in the previous monitoring period and the sum of the second level difference between each monitoring point and the deepest monitoring point in the current monitoring period are obtained as the elevation of the corresponding monitoring point in the current monitoring period.

6. The method according to claim 1, characterized in that, Based on the elevation of the benchmark point, the trigonometric elevation difference, and the third leveling difference between each monitoring point and the portal monitoring point within the current monitoring period, the elevation of each monitoring point within the current monitoring period is determined, specifically including: The elevation of the benchmark point, the trigonometric elevation difference, and the sum of the third leveling difference of each monitoring point relative to the portal monitoring point within the current monitoring period are obtained, and used as the elevation of the corresponding monitoring point within the current monitoring period.

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