Method for determining the diameter of carving tool head for multi-scale slip surface specimens of rock slopes

Abstract

The present invention discloses a method for determining the diameter of a carving tool head for a multi-scale slip surface specimen of a rock slope, comprising: establishing a series of scale slip surface surface morphology models; performing spectrum analysis based on the series of scale slip surface surface morphology models to determine the distribution characteristics of the logarithmic mean square value of the fluctuation height of the slip surface morphology of each scale in the frequency domain; determining the optimal frequency f corresponding to the logarithmic mean square value of the fluctuation height of the slip surface morphology that meets the test requirements; optimal ; Based on the optimal frequency f optimal Determine the optimal sampling interval SI to meet the test requirements optimal ; Based on the optimal sampling interval SI optimal Determine the diameter of the engraving tool head. The method for determining the diameter of the engraving tool head for a multi-scale slip surface specimen on a rock slope of the present invention performs spectral analysis on the slip surface surface morphology model to quantitatively determine the optimal frequency corresponding to the mean square value of the fluctuation height of the spectral components of the slip surface morphology to be retained. This method then obtains the optimal sampling spacing that matches the optimal frequency, providing quantitative guidance for selecting the engraving tool head diameter.

Description

Technical Field

[0001] The invention belongs to the technical field of geotechnical engineering, and particularly relates to a method for determining the diameter of an engraving tool head for a multi-scale slip surface sample of a rock slope. Background Art

[0002] The stability of rock slopes is controlled by a series of large, medium, and small-scale structural surfaces present in the rock mass. The combination of structural surfaces of different scales can form the potential slip surface of the rock slope. Accurately testing the shear strength of the potential slip surface of a rock slope is a fundamental prerequisite for stability evaluation. Due to the significant size effect of structural surfaces, that is, the mechanical properties of structural surfaces of different scales differ, their shear strength generally decreases with increasing scale. Therefore, it is necessary to carve and prepare multi-scale slip surface specimens. Through direct shear testing, the correlation mechanism between the shear strength of large, medium, and small-scale structural surfaces can be clarified, laying the foundation for the accurate determination of the potential slip surface of rock slopes.

[0003] The three-dimensional morphology of natural structural surfaces has certain spectral characteristics, which are composed of spectral components with different frequency characteristics. The wear evolution characteristics of different spectral components during the shearing process have a significant impact on the shear mechanism and shear strength of the structural surface. Therefore, in the process of carving and preparing multi-scale slip surfaces of rock slopes, it is necessary to focus on the spectral characteristics of slip surface samples of different scales. The slip surface samples prepared by carving must fully retain the spectral components related to shear strength. The smaller the sampling interval is usually used, the more complete the effective spectral components that can be retained. However, using too small a sampling interval faces two difficulties: (1) As the scale of the slip surface increases, the required point cloud data increases rapidly at a quadratic rate, and the data processing and storage costs are extremely high; (2) When using a rock carving machine to carve and prepare slip surface samples, the required carving head diameter is too small, making it difficult to carve rocks with higher hardness, and the carving time is too long, which significantly prolongs the entire experimental period.

[0004] Existing researchers typically use methods such as Fourier series, Gaussian filtering, wavelet transforms, and varying sampling accuracies to extract the spectral components of structural surfaces. However, existing methods have yet to propose quantitative indicators for the optimal frequency components to be retained for slip surfaces of varying scales. This makes it impossible to determine the optimal sampling spacing required for preparing slip surface samples at varying scales. Consequently, there is no quantitative standard for selecting engraving tool diameters, making it impossible to meet the requirements for engraving and preparing multi-scale slip surface samples for rock slopes. Summary of the Invention

[0005] The present invention provides a method for determining the diameter of a carving tool head for a multi-scale slip surface sample of a rock slope to solve the above-mentioned technical problems, specifically adopting the following technical solutions:

[0006] A method for determining the diameter of a carving tool head for a multi-scale slip surface sample of a rock slope, comprising:

[0007] Establish a series of scale slip surface morphology models;

[0008] Based on the series of scale slip surface morphology models, spectrum analysis is performed to determine the distribution characteristics of the logarithmic mean square value of the undulation height of each scale slip surface morphology in the frequency domain;

[0009] Determine the optimal frequency f corresponding to the mean square value of the undulation height of the sliding surface morphology that meets the test requirements optimal ;

[0010] Based on the optimal frequency f optimal Determine the optimal sampling interval SI to meet the test requirements optimal ;

[0011] Based on the optimal sampling interval SI optimal Determine the diameter of the engraving bit.

[0012] Furthermore, the specific method for establishing the series-scale slip surface morphology model is:

[0013] Carry out engineering geological survey of rock slopes, collect surface morphological data of slip surfaces along the shear direction, and establish a series of scale slip surface morphological models based on the collected morphological data.

[0014] Furthermore, the distribution characteristics of the logarithmic mean square value of the fluctuation height of the surface morphology of each scale slip surface determined based on spectrum analysis in the frequency domain are calculated by the following formula:

[0015]

[0016] Among them, RMS(f) is the mean square value of the fluctuation height of all frequency components greater than or equal to frequency f in the surface morphology of the slip surface, and PSD(f x ,f y ) is the two-dimensional power spectrum density of the slip surface morphology, f x and f y are the spatial frequencies of the frequency components of the slip surface morphology in the x-axis and y-axis directions, respectively, and f xmin and f xmax f x The minimum and maximum values ​​of f ymin and f ymax f y The minimum and maximum values ​​of .

[0017] Furthermore, the optimal frequency f corresponding to the mean square value of the undulation height of the sliding surface morphology that meets the test requirements is determined by the following formula: optimal :

[0018]

[0019] Furthermore, the value range of m is greater than or equal to 90 and less than or equal to 98.

[0020] Furthermore, m is 95.

[0021] Furthermore, based on the optimal frequency f optimal , determine the optimal sampling interval SI that meets the test requirements through the Nyquist sampling theorem optimal , the calculation formula is as follows:

[0022]

[0023] Furthermore, the optimal sampling interval SI optimal The specific method to determine the diameter of the engraving head is:

[0024] The diameter d of the engraving tool head ranges from SI optimal / 3≤d≤SI optimal / 2.

[0025] Furthermore, when the wall rock strength is greater than 30 MPa, the engraving tool head diameter d is determined to be S1 optimal / 2;

[0026] When the wall rock strength is less than or equal to 30MPa, the engraving head diameter d is determined to be SI optimal / 3.

[0027] Furthermore, the method for determining the diameter of a carving tool head for a multi-scale slip surface sample of a rock slope further comprises:

[0028] Slip surface samples of corresponding scale are prepared by using a rock engraving machine with an engraving tool head of corresponding diameter.

[0029] The benefit of the present invention lies in the method for determining the diameter of the engraving tool head for multi-scale slip surface specimens of rock slopes. By performing spectral analysis on the slip surface surface morphology model, the distribution characteristics of the fluctuation height of the slip surface morphology of each scale in the frequency domain are clarified, so that from the perspective of meeting the test requirements, the optimal frequency corresponding to the mean square value of the fluctuation height of the spectral components of the slip surface morphology to be retained is quantitatively determined. With the help of the Nyquist sampling theorem, a quantitative relationship between the optimal sampling spacing and the optimal frequency is established, which quantitatively guides the selection of the engraving tool head diameter and effectively engraves and prepares multi-scale slip surface specimens of rock slopes, thereby laying the foundation for accurately determining the shear strength of the slip surface of the rock slope. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 Schematic diagram of the method for determining the diameter of the engraving tool head for a multi-scale slip surface specimen of a rock slope according to the present application;

[0032] Figure 2 This is a surface morphology model of the slip surface of a typical tunnel entrance rock slope along the Ningxiang Line tunnel.

[0033] Figure 3 This is a characteristic image of the distribution of the mean square value of the logarithm of the surface morphology fluctuation height of the slip surface of the rock slope at a typical tunnel entrance along the Ningxiang Line Tunnel in the frequency domain. DETAILED DESCRIPTION

[0034] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0035] like Figure 1 The present invention shows a method for determining the diameter of a carving tool head for a multi-scale slip surface specimen of a rock slope, comprising:

[0036] S1: Establish a series of scale slip surface morphology models.

[0037] In the embodiment of the present application, the specific method for establishing the series-scale slip surface morphology model is:

[0038] Conduct an engineering geological survey of rock slopes, collect slip surface morphology data along the shear direction, and build a slip surface morphology model based on this data at a series of scales. This series of scales is determined based on research needs, typically 10 cm, 20 cm, 30 cm, ..., 100 cm, etc.

[0039] S2: Based on the series of scale slip surface morphology models, spectrum analysis is performed to determine the distribution characteristics of the logarithmic mean square value of the undulation height of each scale slip surface morphology in the frequency domain.

[0040] In the embodiment of the present application, the distribution characteristics of the logarithmic mean square value of the undulation height of the surface morphology of each scale slip surface determined based on spectrum analysis in the frequency domain are calculated by the following formula:

[0041]

[0042] Among them, RMS(f) is the mean square value of the fluctuation height of all frequency components greater than or equal to frequency f in the surface morphology of the slip surface, and PSD(f x ,f y ) is the two-dimensional power spectrum density of the slip surface morphology, f x and f y are the spatial frequencies of the frequency components of the slip surface morphology in the x-axis and y-axis directions, respectively, and f xmin and f xmax f x The minimum and maximum values ​​of f ymin and f ymax f y The minimum and maximum values ​​of .

[0043] S3: Determine the optimal frequency f corresponding to the mean square value of the height fluctuation of the sliding surface morphology that meets the test requirements optimal .

[0044] In the embodiment of the present application, the optimal frequency f corresponding to the mean square value of the height fluctuation of the sliding surface morphology that meets the test requirements is determined by the following formula: optimal :

[0045]

[0046] It can be understood that based on the distribution characteristics of the logarithmic mean square value of the undulation height of the slip surface morphology of each scale in the frequency domain, with the goal of retaining the undulation height of the frequency component of m% that has the main contribution to the shear strength, the optimal frequency f corresponding to the mean square value of the undulation height of the slip surface morphology that meets the test requirements is determined. optimal Preferably, the value range of m is greater than or equal to 90 and less than or equal to 98. In the embodiment of the present application, m is 95, that is:

[0047]

[0048] As the frequency f increases, the logarithmic mean square value lg[RMS(f)] of the undulation height of the slip surface gradually decreases. When f increases to a certain value, the value of lg[RMS(f)] can be ignored. The frequency f at this time is the optimal frequency f. optimal The influence of frequency components greater than or equal to frequency f in the surface morphology of the slip surface on the shear strength can be ignored. We only need to focus on all frequency components less than or equal to frequency f in the surface morphology of the slip surface to retain the fluctuation height of 95% of the frequency components that have a major contribution to the shear strength.

[0049] S4: Based on the optimal frequency f optimal Determine the optimal sampling interval SI to meet the test requirements optimal .

[0050] In the embodiment of the present application, based on the optimal frequency f optimal , determine the optimal sampling interval SI that meets the test requirements through the Nyquist sampling theorem optimal , the calculation formula is as follows:

[0051]

[0052] Specifically, it can be seen from the Nyquist sampling theorem that in order to ensure that the discrete surface morphology model reconstructed from the continuous slip surface morphology can accurately represent the spectral components of the slip surface morphology that meet the experimental requirements, the sampling frequency must be at least twice the highest frequency component of the required spectral components, that is, the sampling interval must be twice the reciprocal of the optimal rate component.

[0053] In step S4, the optimal sampling interval SI optimal It can ensure that the surface morphology of the slip surface is less than or equal to the optimal frequency f optimal In actual operation, the sampling interval can be appropriately reduced, but it cannot be greater than the optimal sampling interval SI optimal .

[0054] S5: Based on the optimal sampling interval SI optimal Determine the diameter of the engraving bit.

[0055] Based on the optimal sampling interval SI optimal The specific method to determine the diameter of the engraving head is:

[0056] The diameter d of the engraving tool head ranges from SI optimal / 3≤d≤SI optimal / 2.

[0057] In the embodiment of the present application, when the wall rock strength is greater than 30 MPa, the engraving tool head diameter d is determined to be SI optimal / 2. When the wall rock strength is less than or equal to 30MPa, the engraving head diameter d is determined to be SI optimal / 3.

[0058] In an embodiment of the present application, the method for determining the diameter of a carving tool head for a multi-scale slip surface sample of a rock slope further comprises:

[0059] Slip surface samples of corresponding scale are prepared by using a rock engraving machine with an engraving tool head of corresponding diameter.

[0060] The slip surface of a typical tunnel entrance rock slope along the Ningxiang Line Tunnel was taken as the research object. A laser scanner was used to collect discrete coordinate data of the multi-scale slip surface morphology along the slip surface direction. A series of scale slip surface morphology models were established. The surface morphology model of the slip surface with a scale of 100 mm is shown in the figure below. Figure 2 shown.

[0061] Then, the two-dimensional power spectrum density is used to carry out spectrum analysis on the established slip surface morphology. According to the calculation formula in step S2, the distribution characteristics of the logarithmic mean square value of the undulation height of the slip surface morphology of each scale in the frequency domain are analyzed, and the distribution characteristic image of the logarithmic mean square value of the undulation height of the slip surface morphology in the frequency domain is drawn, as shown in FIG. Figure 3 As shown. With the goal of retaining the 95% frequency component that has the main contribution to the shear strength, according to the calculation formula in step S3, the optimal frequency corresponding to the mean square value of the undulation height of the slip surface morphology that meets the test requirements can be calculated to be 1.0 / mm. Figure 3 It can be seen that for the surface morphology model of a slip surface with a side length of 100 mm, the mean square value of the fluctuation height of all frequency components greater than 1.0 / mm in the slip surface morphology is much less than 0.001 mm. This indicates that frequency components with a frequency greater than 1.0 / mm in the slip surface morphology have minimal impact on the overall morphology. In this case, retaining only the frequency components with a frequency of 1.0 / mm or less in the slip surface morphology can retain the fluctuation height of 95% of the frequency components that contribute significantly to shear strength, thereby meeting the test accuracy requirements. Therefore, for a slip surface specimen with a side length of 10 cm, the optimal frequency is 1.0 / mm.

[0062] Furthermore, according to the formula in step S4, the optimal sampling spacing for a slip surface sample with a side length of 10 cm can be calculated to be 0.5 mm. For slip surface samples of other sizes, the same analysis method can be used to calculate their optimal sampling spacing.

[0063] Finally, based on the optimal sampling spacing for the series of slip surface specimens, a carving tool head with a matching diameter was selected, and the multi-scale slip surface specimens were prepared using a rock engraving machine. For a slip surface specimen with a side length of 10 cm, for example, the optimal sampling spacing is 0.5 mm, and the diameter of the selected carving tool head should be less than 0.25 mm. Using a carving tool head of this size effectively retains the frequency components that contribute primarily to shear strength when processing slip surface specimens, while avoiding the challenges of using a tool head with an excessively small diameter, which results in significant data processing and storage overhead and excessive engraving time.

[0064] The embodiments of this specification are merely examples of implementations of the invention and are provided for illustrative purposes only. The scope of protection of the present invention should not be considered limited to the specific embodiments described in these embodiments. The scope of protection of the present invention also extends to equivalent technical means that can be conceived by a person of ordinary skill in the art based on the invention.

[0065] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any form, and any technical solutions obtained by equivalent replacement or equivalent transformation fall within the scope of protection of the present invention.

Claims

1. A method for determining the diameter of a carving tool head for a multi-scale slip surface specimen of a rock slope, characterized in that: Include: Establish a series of scale slip surface morphology models; Based on the series of scale slip surface morphology models, spectrum analysis is performed to determine the distribution characteristics of the logarithmic mean square value of the undulation height of each scale slip surface morphology in the frequency domain; Determine the optimal frequency f corresponding to the mean square value of the undulation height of the sliding surface morphology that meets the test requirements optimal ; Based on the optimal frequency f optimal Determine the optimal sampling interval SI to meet the test requirements optimal ; Based on the optimal sampling interval SI optimal Determine the diameter of the engraving bit.

2. The method for determining the diameter of a carving tool head for a multi-scale slip surface sample of a rock slope according to claim 1 is characterized in that: The specific method for establishing the series-scale slip surface morphology model is as follows: Carry out engineering geological survey of rock slopes, collect surface morphological data of slip surfaces along the shear direction, and establish a series of scale slip surface morphological models based on the collected morphological data.

3. The method for determining the diameter of a carving tool head for a multi-scale slip surface sample of a rock slope according to claim 1, characterized in that: The distribution characteristics of the logarithmic mean square value of the undulation height of the surface morphology of each scale slip surface determined based on spectrum analysis in the frequency domain are calculated by the following formula: Among them, RMS(f) is the mean square value of the fluctuation height of all frequency components greater than or equal to frequency f in the surface morphology of the slip surface, and PSD(f x ,f y ) is the two-dimensional power spectrum density of the slip surface morphology, f x and f y are the spatial frequencies of the frequency components of the slip surface morphology in the x-axis and y-axis directions, respectively, and f xmin and f xmax f x The minimum and maximum values ​​of f ymin and f ymax f y The minimum and maximum values ​​of .

4. The method for determining the diameter of a carving tool head for a multi-scale slip surface sample of a rock slope according to claim 3, characterized in that: The optimal frequency f corresponding to the mean square value of the undulation height of the sliding surface morphology that meets the test requirements is determined by the following formula optimal :

5. The method for determining the diameter of a carving tool head for a multi-scale slip surface sample of a rock slope according to claim 4, characterized in that: The value range of m is greater than or equal to 90 and less than or equal to 98.

6. The method for determining the diameter of a carving tool head for a multi-scale slip surface sample of a rock slope according to claim 5, characterized in that: m is 95.

7. The method for determining the diameter of a carving tool head for a multi-scale slip surface sample of a rock slope according to claim 1, characterized in that: Based on the optimal frequency f optimal , determine the optimal sampling interval SI that meets the test requirements through the Nyquist sampling theorem optimal , the calculation formula is as follows:

8. The method for determining the diameter of a carving tool head for a multi-scale slip surface sample of a rock slope according to claim 1, characterized in that: Based on the optimal sampling interval SI optimal The specific method to determine the diameter of the engraving head is: The diameter d of the engraving tool head ranges from SI optimal / 3≤d≤SI optimal / 2.

9. The method for determining the diameter of a carving tool head for a multi-scale slip surface sample of a rock slope according to claim 8, characterized in that: When the wall rock strength is greater than 30MPa, the engraving head diameter d is determined to be SI optimal / 2; When the wall rock strength is less than or equal to 30MPa, the engraving head diameter d is determined to be SI optimal / 3.

10. The method for determining the diameter of a carving tool head for a multi-scale slip surface sample of a rock slope according to claim 1, characterized in that: The method for determining the diameter of a carving tool head for a multi-scale slip surface sample of a rock slope further comprises: Slip surface samples of corresponding scale are prepared by using a rock engraving machine with an engraving tool head of corresponding diameter.

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