A method for measuring the slip surface of a geological disaster body based on the galvanic effect

Abstract

The application discloses a kind of based on the measurement method of geologic hazard body slip surface of induced polarization effect, comprising: drilling N work drill holes in the rear end of potential landslide body to be detected;High polarizability and lower viscosity slurry are injected into work drill hole;Using the werner device with equal electrode distance, apparent polarizability under several first electrode distances along the direction of landslide body is obtained;The distance of electrode is increased, and apparent polarizability under several second electrode distances along the direction of landslide body is repeatedly obtained;Apparent polarizability dataset is formed, and apparent polarizability pseudo-section is drawn according to apparent polarizability dataset;According to apparent polarizability pseudo-section, high polarizability distribution law is analyzed, and preliminary slip surface position is obtained;The apparent polarizability dataset is inverted, and apparent polarizability inversion section is obtained;According to apparent polarizability pseudo-section and apparent polarizability inversion section, the accurate slip surface position is obtained.

Description

Technical Field

[0001] This invention relates to the field of landslide and other geological disaster sliding surface measurement and disaster monitoring and early warning technology, and in particular to a method for measuring the sliding surface of a geological disaster body based on the induced polarization effect. Background Technology

[0002] Currently, conventional geophysical methods for detecting slip surfaces in geological disasters such as landslides mainly include direct current resistivity (DC) methods, magnetotelluric methods, and ground-penetrating radar methods. Among them, DC methods, for example, have low accuracy and are difficult to determine the location of slip surfaces. Furthermore, DC methods rely on only one parameter—the difference in electrical properties—making it difficult to determine the development of fractures within the landslide body.

[0003] For example, Xu Hongwu's "High-Density DC Resistivity Method for Detecting Landslide Overburden and Slip Surface" uses a high-density resistivity measurement system to detect landslides. It employs a grid-like survey line layout and combines fixed-section scanning measurement with variable-section continuous rolling scanning measurement. Another example is Liu Zhonggang's "Application of Ground-Penetrating Radar in Landslide Slip Surface Analysis." Yet another example is the Chinese invention patent "Patent Publication No.: CN106677151A, Title: A Method for Determining Slip Surfaces," which uses the slope of the total displacement vector at various monitoring points on the same profile to calculate the slip surface shape curve at a certain coordinate using the least squares method and regression iteration, thus determining the slip surface location. It then uses slope displacement vector angle iteration to approximate the true slip surface of any shape.

[0004] The above cases demonstrate that current technologies primarily rely on differences in electrical or physical properties for detection and analysis. However, the slip surface of typical landslides and other geological hazards is very small relative to the landslide body and is irregular. Existing methods are based on layered models, making detection difficult.

[0005] Therefore, there is an urgent need to propose a logically simple, accurate and reliable method for measuring the slip surface of geological hazard bodies based on the induced polarization effect. Summary of the Invention

[0006] To address the above problems, the present invention aims to provide a method for measuring the slip surface of a geological hazard body based on the induced polarization effect. The technical solution adopted by the present invention is as follows:

[0007] A method for measuring the slip surface of a geological hazard body based on the induced polarization effect, comprising the following steps:

[0008] N boreholes are drilled at the rear end of the potential landslide body to be detected; N is a natural number greater than or equal to 1 and less than 10.

[0009] Inject a cement-based grout with a water-cement ratio greater than 1.2, a viscosity less than 50s, and a polarization greater than 8% into the borehole until the grout fills the borehole and the cement-based grout migrates along the underground voids.

[0010] The apparent polarizability at several first electrode distances along the landslide direction was obtained using a Wenner device with equal electrode spacing.

[0011] Increase the distance between the electrodes and repeatedly collect the apparent polarization at several second electrode distances along the landslide direction;

[0012] A visual polarizability dataset is constructed by combining the visual polarizability at several first electrode distances and several second electrode distances; a pseudo-section diagram of visual polarizability is then drawn based on the visual polarizability dataset.

[0013] Based on the apparent polarizability pseudo-section map, the region with high polarizability located against a background of low apparent polarizability is selected to obtain the preliminary slip surface position;

[0014] The least squares method was used to invert the apparent polarizability dataset and the apparent resistivity dataset to obtain the apparent resistivity amplitude inversion cross-section and the phase angle inversion cross-section.

[0015] Based on the apparent polarizability pseudo-section map, apparent resistivity amplitude inversion section map, and phase inversion section map, regions with slip surface polarization characteristics are selected respectively; morphological analysis is used to analyze the distribution pattern of regions with slip surface polarization characteristics to obtain the precise slip surface location.

[0016] Furthermore, the Wenner device is equipped with a power supply electrode and a measuring electrode; when the landslide body is detected, a constant current is supplied to the landslide body to be measured using one end of the power supply electrode; when the potential difference between the measuring electrodes tends to saturate, that is, when the potential difference does not change with time; the power supply electrode is disconnected, and the potential difference between the measuring electrodes after the power is cut off is measured.

[0017] Preferably, the apparent polarizability η is expressed as:

[0018]

[0019] Where T represents the duration of a single charge, t represents the time for measuring the secondary field after power failure; ΔU(T) represents the potential difference between the measuring electrodes when they reach saturation after charging time T, and ΔU2(t) represents the potential difference between the measuring electrodes at time t after power failure.

[0020] Preferably, it further includes: obtaining the apparent integral polarizability M using formula (2). a Its expression is:

[0021]

[0022] Where t1 and t2 represent the measurement times, V p V(t) represents the voltage supplied by the power supply electrode to the ground, and V(t) represents the voltage change over time after the power is cut off.

[0023] Furthermore, based on the apparent polarizability pseudo-section map, regions with high polarizability located against a low apparent polarizability background are selected to obtain the preliminary slip surface location; the specific steps are as follows:

[0024] A linear search algorithm was used to identify large areas with polarizability values ​​less than 2%-5%, and to provide exploration background.

[0025] Find continuous regions corresponding to the polarizability values ​​of the exploration background that are twice or more, and select them by bounding box.

[0026] Furthermore, the least squares method is used to invert the apparent polarizability dataset and the apparent resistivity dataset to obtain the apparent resistivity amplitude inversion cross-sectional map and the phase angle inversion cross-sectional map. The specific steps are as follows:

[0027] Based on the relationship that the negative value of 1.3 times the apparent polarizability is approximately equal to the phase angle, the apparent polarizability dataset is converted into a phase angle dataset.

[0028] Preprocess the apparent resistivity dataset and phase angle dataset;

[0029] Inversion calculations are performed on the preprocessed apparent resistivity dataset and phase angle dataset to obtain apparent resistivity amplitude inversion cross-sectional plots and phase angle inversion cross-sectional plots.

[0030] Furthermore, based on the apparent polarizability pseudo-section map, apparent resistivity amplitude inversion section map, and phase inversion section map, regions with slip surface polarization characteristics are selected respectively; morphological analysis is used to determine the distribution pattern of these regions and obtain the precise slip surface location; the specific steps are as follows:

[0031] Obtain the absolute values ​​of the resistivity amplitude and phase angle of the exploration background; the absolute values ​​of the resistivity amplitude and phase angle of the exploration background are both average values, which are the average values ​​of multiple measurements;

[0032] On the apparent polarizability pseudo-section map, select the first continuous region corresponding to the polarizability value of the exploration background that is more than twice the polarizability value.

[0033] Select areas with resistivity amplitude less than [value missing] on the apparent resistivity amplitude inversion section diagram. The second continuous region of resistivity amplitude in the exploration background;

[0034] On the phase angle inversion profile, select the third continuous region where the absolute value of the phase angle is greater than twice the absolute value of the phase angle of the exploration background.

[0035] By using morphological analysis of the first, second, and third continuous regions, the regions with the same shape and overlapping with the first, second, and third continuous regions are obtained, which are the precise locations of the slip surface.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) This invention is based on the induced polarization effect of cement-based slurry materials with low resistivity and high polarizability, and uses the induced polarization effect for measurement. It does not need to consider the model and volume effect, and can accurately and reliably measure the slip surface directly.

[0038] (2) This invention involves drilling several boreholes at the rear end of the landslide body to be tested and injecting a grout with high polarizability and low viscosity. Due to the lubricity of the grout, it easily flows from the high point of the landslide body to the low point and invades the landslide body. This process mainly focuses on the sliding surface, slowly filling the voids in the sliding surface, so as to utilize the induced polarization effect of the grout material with low resistivity and high polarizability in the voids. The construction is simple and the measurement is efficient and reliable.

[0039] (3) The present invention ingeniously constructs a pseudo-section map of apparent polarizability and uses a linear search algorithm to pick out the region of high polarizability in the background of low apparent polarizability, and analyzes the distribution law of high polarizability to obtain the preliminary slip surface location. Its advantage is that the high polarizability feature is easily identified in the background of low polarizability, and the high polarizability location is the location where there is more slurry filling, that is, the location with large voids, which is the place where the geological disaster body slips.

[0040] (4) This invention ingeniously uses the least squares method to invert the apparent polarizability dataset and the apparent resistivity dataset to obtain the apparent resistivity amplitude inversion cross-sectional map and the phase angle inversion cross-sectional map. Based on the apparent polarizability pseudo-cross-sectional map, the apparent resistivity amplitude inversion cross-sectional map and the phase inversion cross-sectional map, regions with slip surface polarization characteristics are selected respectively. The distribution pattern of regions with slip surface polarization characteristics is obtained by morphological analysis to obtain the accurate slip surface position. The advantage is that the three reference regions jointly constrain a region with a high anomaly, effectively ensuring the accuracy and reliability of slip surface identification.

[0041] In summary, this invention has the advantages of simple logic, accuracy and reliability, and high measurement efficiency. It has high practical value and promotion value in the fields of landslide and other geological disaster sliding surface measurement and disaster monitoring and early warning technology. Attached Figure Description

[0042] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope of protection. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1This is a schematic diagram of the grouting principle of the present invention.

[0044] Figure 2 This is an amplitude distribution diagram of the forward model of the present invention.

[0045] Figure 3 This is a phase distribution diagram of the forward model of the present invention.

[0046] Figure 4 This is an amplitude distribution diagram of the forward model of the present invention after processing by the finite element method or the finite difference method.

[0047] Figure 5 This is a phase distribution diagram of the forward model of the present invention after processing by the finite element method or the finite difference method.

[0048] Figure 6 A schematic diagram for stimulating the polarization effect. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this application clearer, the present invention will be further described below with reference to the accompanying drawings and embodiments. The embodiments of the present invention include, but are not limited to, the following embodiments. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0050] In this embodiment, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0051] The terms "first" and "second," etc., used in the specification and claims of this embodiment are used to distinguish different objects, not to describe a specific order of objects. For example, "first target object" and "second target object," etc., are used to distinguish different target objects, not to describe a specific order of target objects.

[0052] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0053] In the description of the embodiments in this application, unless otherwise stated, "multiple" means two or more. For example, multiple processing units means two or more processing units; multiple systems means two or more systems.

[0054] like Figures 1 to 5 As shown, this embodiment provides a method for measuring the slip surface of geological hazards based on the induced polarization effect. This addresses the inaccuracy of existing technologies that rely primarily on differences in electrical or physical properties to determine the slip surface. The slip surface of conventional landslides and other geological hazards is very small and irregular relative to the landslide body. Existing technologies use layered models, which are difficult to detect. This embodiment is based on the induced polarization effect of materials, utilizing this effect for measurement. It does not require consideration of model and volume effects, and can accurately and reliably measure the slip surface directly.

[0055] First, it's necessary to introduce the principle of induced polarization (IP) measurement: IPI is an artificial source electrical exploration method based on the difference in polarizability of rocks and minerals. Its physical basis is the induced polarization effect, that is, when a steady current is supplied to the rock or mineral, the potential difference slowly increases and gradually approaches saturation as the power supply time increases. After the power is cut off, the potential difference will drop to a certain value at the moment of power failure, and then slowly decay over time until it gradually approaches zero. Figure 6 As shown, (a) represents the relationship between the steady current of the charging electrode and the connection time, and (b) represents the relationship between the potential obtained by the measuring electrode and time.

[0056] In this embodiment, to understand the approximate distribution of anomalies in the subsurface medium, a survey line perpendicular to the direction of the anomaly is selected for measurement. A Wenner device with equidistant electrode spacing is used, i.e., AM = MN = NB = a, where a increases with increasing exploration depth. The MN measuring electrode needs to be a non-polarized electrode. Power is supplied to the subsurface via the AB electrodes, and then, after a very short time following power failure, the MN electrode measures the potential difference.

[0057] In this embodiment, the apparent polarizability of the recorded point can be obtained using formula (1), and its expression is:

[0058]

[0059] Where T represents the duration of a single charge, t represents the time for measuring the secondary field after power failure; ΔU(T) represents the potential difference between the measuring electrodes when they reach saturation after charging time T, and ΔU2(t) represents the potential difference between the measuring electrodes at time t after power failure.

[0060] Alternatively, the apparent integral polarizability can be calculated using formula (2), which is expressed as follows:

[0061]

[0062] Where t1 and t2 represent the measurement times, t1 to t2 is the measurement time interval, and V p V(t) represents the voltage supplied by the power supply electrode to the ground, and V(t) represents the voltage change over time after the power is cut off.

[0063] In this embodiment, the method for measuring the slip surface of a geological hazard body based on the induced polarization effect includes the following steps:

[0064] First, several drilled holes are set at the rear end of the potential landslide body, and a cement-based grout with high polarizability and low viscosity (water-cement ratio greater than 1.2, viscosity less than 50s, polarizability greater than 8%) is injected into the holes. Due to the lubricity of the grout, it easily flows from the high point of the landslide body to the low point, and this process mainly focuses on the sliding surface, slowly filling the voids on the sliding surface. The viscosity of the grout is determined using the Marshall method, which requires a Marshall funnel, a measuring cup, and a mud cup. The specific test method is as follows: Mix the grout according to the design, pour 1500ml of grout through a sieve into the Marshall funnel using a measuring cup, and simultaneously block the outlet with your finger. Place a 946ml measuring cup below the outlet, release your finger, and start a stopwatch. Stop the stopwatch when the grout surface is tangent to the measuring cup surface. The time it takes for the grout to flow out is the viscosity of the grout, measured in seconds.

[0065] Until the voids in the sliding surface corresponding to the landslide are completely filled, starting from a certain position on the high part of the landslide surface, power supply electrode AB and measuring electrode MN (non-polarized electrode) are arranged. Select an electrode spacing with a shallow exploration depth and an appropriate power supply size, record the potential difference before the power supply is disconnected and the point difference at a certain time t after the power supply is disconnected, and calculate the apparent polarizability at the measurement position using the apparent polarizability formula (1). Move the measuring device from the high part to the low part of the landslide surface, repeat the above power supply disconnection measurement process, and collect a series of apparent polarizabilities at the same depth.

[0066] Increase the distance between the electrodes and repeat the power-off measurement process described above to obtain a series of apparent polarizabilities at another depth. Finally, a series of apparent polarizabilities at several different depths are obtained, which constitutes the apparent polarizability dataset.

[0067] Based on the apparent polarimetric dataset, a pseudo-section map of apparent polarimetrics is drawn. Using this map, a linear search algorithm is employed to select regions of high polarimetrics located against a low apparent polarimetric background. The distribution pattern of these high polarimetric regions is then analyzed to obtain the preliminary location of the slip surface. Alternatively, these regions can be selected manually.

[0068] Here, a linear search algorithm is used to identify large areas with polarizability values ​​less than 2%-5%, which are then designated as exploration backgrounds. Next, continuous areas corresponding to the polarizability values ​​of the exploration backgrounds, which are twice or more in value, are identified and selected.

[0069] In addition, the least squares method is used to invert the apparent polarizability dataset and the apparent resistivity dataset to obtain the apparent resistivity amplitude inversion cross-section and the phase angle inversion cross-section. The specific steps are as follows:

[0070] (1) Based on the relationship that the negative value of 1.3 times the apparent polarizability is approximately equal to the phase angle, the apparent polarizability dataset is converted into a phase angle dataset;

[0071] (2) Preprocess the apparent resistivity dataset and phase angle dataset, including: excluding values ​​with huge differences and inserting missing values, which is a conventional preprocessing method.

[0072] (3) Perform inversion calculations on the preprocessed apparent resistivity dataset and phase angle dataset to obtain the apparent resistivity amplitude inversion cross-section and the phase angle inversion cross-section.

[0073] In this embodiment, based on the apparent polarizability pseudo-section map, the apparent resistivity amplitude inversion section map, and the phase inversion section map, and by selecting regions with slip surface polarization characteristics, the precise slip surface position is obtained; specifically:

[0074] (1) Obtain the absolute values ​​of resistivity amplitude and phase angle of the exploration background. The absolute values ​​of resistivity amplitude and phase angle of the exploration background are average values ​​obtained through multiple measurements.

[0075] (2) Select the first continuous region on the apparent polarizability pseudo-section map that corresponds to the polarizability value of the exploration background that is more than twice the value of the polarizability value.

[0076] (3) Select the area with a resistivity amplitude less than a certain value on the apparent resistivity amplitude inversion section diagram. The second continuous region of resistivity amplitude in the exploration background;

[0077] (4) On the phase angle inversion section map, select the third continuous region where the absolute value of the phase angle is greater than twice the absolute value of the phase angle of the exploration background.

[0078] (5) Use morphological analysis of the first continuous region, the second continuous region and the third continuous region to find the region with the same shape and that overlaps with the first continuous region, the second continuous region and the third continuous region, which is the precise position of the slip surface.

[0079] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any changes made based on the design principles of the present invention, or any non-creative modifications made thereon, shall fall within the scope of protection of the present invention.

Claims

1. A method for measuring the slip surface of a geological hazard body based on the induced polarization effect, characterized in that, Includes the following steps: N boreholes are drilled at the rear end of the potential landslide body to be detected; N is a natural number greater than or equal to 1 and less than 10. Inject a cement-based grout with a water-cement ratio greater than 1.2, a viscosity of less than 50s, and a polarization rate greater than 8% into the borehole until the grout fills the borehole and the cement-based grout migrates along the underground voids. The apparent polarizability at several first electrode distances along the landslide direction was obtained using a Wenner device with equal electrode spacing. Increase the distance between the electrodes and repeatedly collect the apparent polarization at several second electrode distances along the landslide direction; A visual polarizability dataset is constructed by combining the visual polarizability at several first electrode distances and several second electrode distances; a pseudo-section diagram of visual polarizability is then drawn based on the visual polarizability dataset. Based on the apparent polarizability pseudo-section map, the region with high polarizability located against a background of low apparent polarizability is selected to obtain the preliminary slip surface position; The least squares method was used to invert the apparent polarizability dataset and the apparent resistivity dataset to obtain the apparent resistivity amplitude inversion cross-section and the phase angle inversion cross-section. Based on the apparent polarizability pseudo-section map, apparent resistivity amplitude inversion section map, and phase angle inversion section map, regions with slip surface polarization characteristics are selected respectively; morphological analysis is performed on the regions with slip surface polarization characteristics, and the distribution law of the regions with slip surface polarization characteristics is determined to obtain the precise slip surface position.

2. The method for measuring the slip surface of a geological hazard body based on the induced polarization effect according to claim 1, characterized in that, The Wenner device is equipped with a power supply electrode and a measuring electrode. When the landslide is detected, a constant current is supplied to the landslide using one end of the power supply electrode. When the potential difference between the measuring electrodes tends to saturate, that is, when the potential difference does not change with time, the power supply electrode is disconnected, and the potential difference between the measuring electrodes after the power is cut off is measured.

3. A method for measuring the slip surface of a geological hazard body based on the induced polarization effect according to claim 1 or 2, characterized in that, The apparent polarization The expression is: （1） Where T represents the duration of a single charge, and t represents the time for measuring the secondary field after power failure; This represents the potential difference between the measuring electrodes that reach saturation after a charging time T. This represents the potential difference between the measuring electrodes at time t after the power is turned off.

4. The method for measuring the slip surface of a geological hazard body based on the induced polarization effect according to claim 1, characterized in that, Based on the apparent polarizability profile, regions with high polarizability located against a low apparent polarizability background are selected to obtain the preliminary slip surface location; the specific steps are as follows: A linear search algorithm was used to identify large areas with polarizability values ​​less than 2%, which were then used as exploration background. Find the continuous region corresponding to the polarizability value of the exploration background that is greater than or equal to twice the polarizability value, and select it by box.

5. The method for measuring the slip surface of a geological hazard body based on the induced polarization effect according to claim 1, characterized in that, The least squares method is used to invert the apparent polarizability dataset and the apparent resistivity dataset to obtain the apparent resistivity amplitude inversion cross-section and the phase angle inversion cross-section. The specific steps are as follows: Based on the relationship that the negative value of 1.3 times the apparent polarizability is approximately equal to the phase angle, the apparent polarizability dataset is converted into a phase angle dataset. Preprocess the apparent resistivity dataset and phase angle dataset; Inversion calculations are performed on the preprocessed apparent resistivity dataset and phase angle dataset to obtain apparent resistivity amplitude inversion cross-sectional plots and phase angle inversion cross-sectional plots.

6. The method for measuring the slip surface of a geological hazard body based on the induced polarization effect according to claim 4, characterized in that, Based on the apparent polarizability pseudo-section map, apparent resistivity amplitude inversion section map, and phase angle inversion section map, regions with slip surface polarization characteristics are selected. Morphological analysis is used to determine the distribution patterns of these regions and the precise location of the slip surface. The specific steps are as follows: Obtain the absolute values ​​of the resistivity amplitude and phase angle of the exploration background; On the apparent polarizability pseudo-section map, select the first continuous region corresponding to the polarizability value of the exploration background that is more than twice the polarizability value. Select areas with resistivity amplitude less than [value missing] on the apparent resistivity amplitude inversion section diagram. The second continuous region of resistivity amplitude in the exploration background; On the phase angle inversion profile, select the third continuous region where the absolute value of the phase angle is greater than twice the absolute value of the phase angle of the exploration background. Morphological analysis is performed on the first, second, and third continuous regions to determine the regions with the same shape that overlap with the first, second, and third continuous regions. These regions are the precise locations of the slip surface.

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