A method for slope stability evaluation based on anchor rod visualization device

Abstract

The application discloses a kind of slope stability evaluation methods based on anchor rod visualization device;It relates to geotechnical engineering slope support and monitoring technical field, slope end baffle is sleeved on anchor rod, anchor rod is also equipped with outer end baffle and visualization device;Outer end baffle is fixedly connected on anchor rod, and compensation spring is arranged between outer end baffle and slope end baffle;Visualization device includes shell and piston, piston is slidably connected in shell, and display cavity is formed between the two, and a plurality of carrier cavities are further provided on shell;The evaluation method includes the following contents: constructing slope stability evaluation model;Obtain anchor rod arrangement parameter, obtain anchor rod prestress loss coefficient by visualization device;Iterative solution obtains the safety factor of slope under current anchor rod reinforcement condition;The device can intuitively reflect the graded loss state of anchor rod prestress through visualization device;Combined with stability evaluation method, the color display result of single anchor rod can be quickly mapped into overall slope stability index.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering slope support and monitoring technology, and in particular to a slope stability assessment method based on an anchor bolt visualization device. Background Technology

[0002] Landslides are the most common geological hazard in open-pit mines, and prestressed anchor reinforcement is one of the important measures for landslide prevention. Experts and scholars in the field of geotechnical engineering have focused on studying the reinforcement effect and mechanism of prestressed anchors using different theories and methods, and some scholars have used numerical simulation to analyze the stability of anchor-reinforced slopes.

[0003] However, prestressed anchors alter the stability of the slope itself. Furthermore, after tensioning and locking, the prestress of the anchor is not constant but is affected by factors such as surrounding rock creep, temperature and humidity changes, anchor stress relaxation, micro-slippage of the anchoring section, construction deviations, and external disturbances, gradually leading to prestress loss and further altering the slope's stability. This factor must be considered when assessing slope stability. Moreover, several prestressed anchors are often installed on the same slope, and the specific prestress loss of each anchor member differs. Therefore, assessing slope stability under these circumstances would undoubtedly involve a huge amount of calculation work and be very time-consuming. Summary of the Invention

[0004] In order to assess the stability of anchored slopes even when prestress loss occurs, this application provides a slope stability assessment method based on an anchor visualization device.

[0005] This application provides a slope stability assessment method based on an anchor bolt visualization device, employing the following technical solution:

[0006] A slope stability assessment method based on an anchor bolt visualization device is provided. The anchor bolt is slidably fitted with a slope end baffle for abutting the slope. The anchor bolt is also equipped with an outer end baffle and a visualization device. The outer end baffle is fixedly connected to the anchor bolt. A compensation spring is provided between the outer end baffle and the slope end baffle. When the anchor bolt is tensioned and anchored, the compensation spring is in a compressed state.

[0007] The visualization device includes a housing and a piston. The housing is connected to the slope end baffle, and the piston is connected to the outer end baffle. The piston is slidably connected in the housing, forming a display cavity between the two. Multiple carrier cavities are spaced apart along the axial direction of the anchor rod on the housing. The carrier cavities contain different colored indicator materials. The piston slides to drive the carrier cavities to communicate with or disconnect from the display cavity.

[0008] In this assessment method: the logarithmic spiral surface failure mechanism is used to describe the slope sliding surface, and a slope stability assessment model is constructed; the spatial arrangement parameters of the anchor bolts are obtained, and the anchor bolt prestress loss coefficient is obtained through a visualization device; the safety factor of the slope under the current anchor bolt reinforcement condition is obtained by iterative solution.

[0009] Optionally, the housing is further provided with a plurality of partition components at intervals, the partition components being disposed between two adjacent carrier cavities; the partition components include a partition spring and a partition plate, the partition plate being slidably connected to the housing in the radial direction of the housing, and the partition spring being used to drive the partition plate to insert into the display cavity to separate the display cavity.

[0010] Optionally, the housing is further provided with a frame, the partition assembly is disposed inside the frame, one end of the partition spring abuts against the partition plate, and the other end abuts against the inner top wall of the frame.

[0011] Optionally, a logarithmic spiral surface failure mechanism can be used to describe the slope sliding surface, and its curve equation is given by the angle of inclination. The expression:

[0012] ;

[0013] ;

[0014] In the formula, This represents the polar radius from any point on the logarithmic spiral to the center of rotation O. This represents the distance from the center of rotation O to the starting point A of the sliding motion at the top of the slope. Indicates the internal friction angle of rock and soil; The starting angle of the logarithmic spiral, The terminal angle of the logarithmic spiral, the most dangerous slip surface. and Determined by searching the calculation code; H represents the slope height.

[0015] Optionally, the slope stability assessment model is based on the balance between the work done by external forces and the dissipation of internal energy, and its specific contents are as follows:

[0016] ;

[0017] In the formula, This indicates the power of the work done by the weight of the sliding soil. This represents the power dissipated within the smooth surface. This indicates the external force power provided by the anchor bolt reinforcement;

[0018] ;

[0019] In the formula, Indicates the weight of soil and rock. It is the rotational angular velocity of the sliding body; The first integral factor is related to the slope geometry and the anchor bolt position. This is the second integral factor related to the slope geometry and anchor bolt location. The third integral factor is related to the slope geometry and anchor position;

[0020] ;

[0021] In the formula, the reduced cohesion satisfy , It is cohesive force; This is a reduction factor, reflecting the stability of the slope under the current anchor reinforcement conditions; simultaneously, the reduced friction angle... satisfy: ;

[0022] ;

[0023] In the formula, This indicates the ultimate bearing capacity of the prestressed anchor. This indicates the anchor bolt prestress locking value. Indicates the polar radius of the anchorage point. This represents the polar angle of the anchor point in polar coordinates. Indicates the anchorage angle of the anchor bolt. The prestress loss coefficient of the anchor bolt is roughly determined by reading the color of the color indicator material in the display cavity.

[0024] Optional, The calculation formula is as follows:

[0025] ;

[0026] ;

[0027] ;

[0028] in This is represented as the slope angle.

[0029] Optionally, the color indicator materials are incompatible; when one color appears in the display cavity, the anchor bolt prestress loss coefficient ranges from [value missing]. When two colors appear in the display cavity, the range of the anchor bolt prestress loss coefficient is: When three colors appear in the display cavity, the range of the anchor bolt prestress loss coefficient is: The precise values ​​are determined based on the pre-established calibration relationship between piston displacement and prestress loss coefficient.

[0030] In summary, this application includes the following beneficial technical effects:

[0031] The device of this invention can intuitively reflect the graded loss state of anchor bolt prestress through a visualization device without relying on external power supply; combined with the stability assessment method of this application, the color display result of a single anchor bolt can be quickly mapped to the overall stability evaluation index of the slope; and it is applicable to slope engineering with insufficient power supply or difficult wiring, and has significant engineering practical value. Attached Figure Description

[0032] Figure 1 This is an overall structural diagram of the initial state of the anchor bolts used in the slope stability assessment method based on the anchor bolt visualization device of this application when the anchor bolts have just completed tensioning and anchoring.

[0033] Figure 2 yes Figure 1 An overall structural diagram of the two baffles and the visualization device after prestress loss occurs;

[0034] Figure 3 yes Figure 2 The overall structure diagram of the separator component.

[0035] Explanation of reference numerals in the attached figures:

[0036] 1. Anchor bolt; 2. Slope end baffle; 3. Outer end baffle; 4. Compensating spring; 5. Housing; 6. Piston; 7. Carrier cavity; 8. Separating assembly; 9. Separating plate; 10. Separating spring. Detailed Implementation

[0037] The following is in conjunction with the appendix Figure 1-3 This application will be described in further detail.

[0038] This application discloses a slope stability assessment method based on an anchor bolt visualization device. This method is used to assess the stability of slopes that have already been reinforced with anchor bolts. The method considers the prestress loss of the anchor bolts and can comprehensively evaluate slope stability. The method includes the following:

[0039] In limit analysis theory, a slope is considered to reach its limit state, or critical sliding state, when the work done by external forces and the dissipation of internal energy are in equilibrium. However, for the vast majority of slopes, they are in a stable state under undisturbed conditions, and the safety factor can be used as a quantitative indicator to evaluate their stability.

[0040] The strength reduction method is a widely accepted method for calculating the safety factor. The method involves applying strength parameters (cohesion, etc.) to the slope soil. Friction angle After reducing the parameters and substituting them into the work-balance equation, find the minimum reduction coefficient that makes the work-balance equation hold true. This is the desired safety factor.

[0041] Therefore, we first construct the failure mechanism of the slope under the limit state, and use the logarithmic spiral surface failure mechanism to describe the slope sliding surface. Its curve equation is given by the angle of inclination. The expression:

[0042] ;

[0043] ;

[0044] In the formula, This represents the polar radius from any point on the logarithmic spiral to the center of rotation O. This represents the distance from the center of rotation O to the starting point A of the sliding motion at the top of the slope. Indicates the internal friction angle of soil and rock; and These are the starting and ending angles of the logarithmic spiral, and the angle of the most dangerous slip surface. and Determined through code search; H represents the slope height;

[0045] Then, a slope stability assessment model is constructed. The slope stability assessment model is based on the balance between the work done by external forces and the dissipation of internal energy. Its specific contents are as follows:

[0046] ;

[0047] In the formula, This indicates the power of the work done by the weight of the sliding soil. This represents the power dissipated within the smooth surface. This indicates the external force power provided by the anchor bolt reinforcement;

[0048] ;

[0049] In the formula, Indicates the weight of soil and rock. It is the rotational angular velocity of the sliding body; This is an integral factor related to slope geometry and anchor bolt location;

[0050] ;

[0051] In the formula, The cohesive force is [value]; and the reduced cohesive force satisfies [condition]. , This is a reduction factor, reflecting the stability of the slope under the current anchor reinforcement conditions; simultaneously, the reduced friction angle... satisfy: ;

[0052] ;

[0053] In the formula, Ultimate bearing capacity of prestressed anchor bolts This indicates the prestress lock value of the slope. Indicates the polar radius of the anchorage point. This represents the polar angle of the anchor point in polar coordinates. The anchorage angle of the anchor bolt is a parameter representing the spatial arrangement of the anchor bolt. This represents the prestress loss coefficient of the anchor bolt;

[0054] For mixed display states of multiple anchor bolts, the prestress value of each anchor bolt can be determined by comprehensively using the weighted average method, the worst-case principle, or the spatial location weighted method, and then the current slope safety factor can be calculated.

[0055] The calculation formula is as follows:

[0056] ;

[0057] ;

[0058] ;

[0059] in This is represented as the slope angle;

[0060] The minimum value that makes the external force power equal to the internal energy dissipation power is obtained by iterative solution. The value is the safety factor obtained.

[0061] In this application, in order to quickly obtain the prestress loss coefficient of the anchor rod 1, a visualization device is also installed on the anchor rod 1. A slope end baffle 2 for abutting the slope is slidably sleeved on the anchor rod 1. An outer end baffle 3 and a visualization device are also provided on the anchor rod 1. The outer end baffle 3 is fixedly connected to the anchor rod 1. A compensation spring 4 is provided between the outer end baffle 3 and the slope end baffle 2. When the anchor rod 1 is tensioned and anchored, the compensation spring 4 is in a compressed state. When the anchor rod 1 experiences prestress loss, the anchor rod 1 gradually moves away from the slope, and the compensation spring 4 gradually extends, thereby driving the slope end baffle 2 to always abut against the slope surface, while the outer end baffle 3 gradually moves away from the slope end baffle 2.

[0062] The visualization device includes a housing 5 and a piston 6. The housing 5 is connected to the slope end baffle 2, and the piston 6 is connected to the outer end baffle 3. The piston 6 is slidably connected in the housing 5, forming a display cavity between the two. Multiple carrier cavities 7 are spaced apart along the axial direction of the anchor rod 1 on the housing 5. The carrier cavities 7 contain different colored indicator materials. The piston 6 slides to drive the carrier cavities 7 to communicate with or disconnect from the display cavity.

[0063] A soft plug is detachably connected to the top of the carrier cavity 7, and color indicator material can be injected into the carrier cavity 7 by removing the soft plug.

[0064] When the outer end baffle 3 drives the piston 6 to begin sliding in the housing 5, the color indicator material in the carrier cavity 7 gradually flows into the display cavity. The surface of the housing 5 is provided with a transparent observation window, or the entire housing 5 is made of transparent material; the prestress loss coefficient of the anchor rod 1 can be quickly read by color.

[0065] In this embodiment, three carrier cavities 7 are provided, each containing a red, green, or yellow color indicator material. The green indicator material can be a green long-afterglow luminescent material, the yellow indicator material can be yellow fluorescent particles or yellow color-developing particles, and the red indicator material can be a red color-developing or long-afterglow material. Preferably, a moisture-resistant, weather-resistant, and non-toxic encapsulation material is used. When the prestress loss of the anchor rod 1 is small, the piston 6 has not yet moved to the first threshold position, all connecting holes are blocked, and the display cavity does not display any color. When the prestress loss of the anchor rod 1 reaches the first threshold, the piston 6 moves to the first connecting hole, allowing the green indicator material in the first carrier cavity 7 to enter the display cavity. When the prestress loss continues to increase to the second threshold, the piston 6 further moves to the second connecting hole, allowing the yellow indicator material to enter the display cavity. When the prestress loss reaches the third threshold, the red indicator material enters the display cavity to form a higher level of warning.

[0066] To prevent the indicator materials entering the display cavity at different stages from mixing with each other, this embodiment also provides a plurality of partition components 8 at intervals on the housing 5. The partition components 8 are disposed between two adjacent carrier cavities 7. The partition component 8 includes a partition spring 10 and a partition plate 9. The partition plate 9 is slidably connected to the housing 5 in the radial direction. The housing 5 is also provided with a frame. The partition components 8 are disposed inside the frame. One end of the spring abuts against the partition plate 9, and the other end abuts against the top wall inside the frame. The partition spring 10 is used to drive the partition plate 9 to insert into the housing 5 to separate the display cavity.

[0067] Initially, the separator plate 9 is held in place by the piston 6 and cannot enter the display cavity. Once the piston 6 moves beyond the corresponding threshold position, the restriction on the separator plate 9 is released. Pushed by the separator spring 10, the separator plate 9 quickly enters the display cavity through the corresponding opening, separating the indicator material entering the display cavity in the two stages. On-site personnel can observe the relatively clear color partitions through the light-transmitting observation window, thus more accurately determining the prestress loss stage.

[0068] Since the separating component 8 has been used in this embodiment, the color indicator material can be a compatible indicator material. If the separating component 8 is not used, the color indicator material needs to be an indicator material that does not mix with each other.

[0069] When only green appears in the display cavity, the range of the anchor bolt prestress loss coefficient is: When both green and yellow appear in the display cavity, the range of the anchor bolt prestress loss coefficient is: When green, yellow, and red colors appear simultaneously in the display cavity, the range of the anchor bolt prestress loss coefficient is: The precise values ​​are determined based on the pre-established calibration relationship between piston displacement and prestress loss coefficient.

[0070] To improve the accuracy of the initial reading, the number of carrier cavities and color indicator materials can be increased, and the whole can be divided into smaller units.

[0071] The following example uses a specific actual slope:

[0072] Consider a homogeneous soil slope with a slope height of... slope angle rock and soil weight Cohesion internal friction angle The slope is equipped with double rows of prestressed anchor bolts, with the anchor bolt inclination angle... Ultimate anchoring force of anchor bolt design Design prestress locking value .

[0073] Based on the aforementioned slope parameters, and combined with the slope geometry and anchor spatial arrangement parameters (the effective radius rT and corresponding polar angle θT of each anchor are determined according to the actual borehole location), the safety factor under different prestress loss thresholds is calculated. In the initial state (where there is no prestress loss in the anchors), the anchor prestress loss coefficient is taken as 0, and the safety factor under this state is used as the benchmark value. Taking two rows of anchors as an example, it is assumed that the anchor arrangement is similar to the anchor arrangement under the grid-shaped frame anchor support, that is, the lower row of anchors is arranged at 1 / 4H from the slope toe, and the upper row of anchors is arranged at 1 / 4H from the slope top. The two-dimensional plane strain model does not consider the anchor distribution in the width direction, but the actual anchor spacing is consistent with the longitudinal direction.

[0074] Specifically, the polar angle and polar radius corresponding to the anchor head position are calculated as follows (anchor numbers are counted from bottom to top):

[0075] ;

[0076] ;

[0077] ;

[0078] ;

[0079] in This represents the distance from the center of rotation O to the toe of the slope, specifically calculated as follows: , The slope angle is 55°, and the anchor bolt inclination angle is 15°.

[0080] Based on the above calculation results, the correspondence between the anchor bolt prestress loss classification and the visualization display is set as follows:

[0081] Green display area: Prestress loss ≤10% (safety factor ≥1.420), indicating that the anchor bolts are in good working condition and the slope as a whole is in a high safety reserve state;

[0082] Yellow display area: Prestress loss 10%–20% (safety factor) This indicates that the anchor bolt has experienced a moderate degree of prestress loss, resulting in a decrease in the safety factor. It is recommended to increase the frequency of observation and inspection.

[0083] Red display area: Prestress loss 20%–30% (safety factor) This indicates that the prestress loss is significant and the safety factor has decreased markedly, requiring re-tensioning or supplementary reinforcement measures.

[0084] It should be noted that when the prestress loss exceeds 30%, the safety factor will further decrease to below 1.382. In the project, timely intervention should be carried out according to the actual warning threshold, and if necessary, the emergency reinforcement plan for the slope should be activated to prevent the slope from entering an unstable or instable state.

[0085] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A slope stability assessment method based on an anchor bolt visualization device, wherein a slope end baffle for abutting the slope is slidably fitted on the anchor bolt, characterized in that: The anchor bolt is also equipped with an outer end baffle and a visualization device; the outer end baffle is connected to the anchor bolt, and a compensation spring is provided between the outer end baffle and the slope end baffle. When the anchor bolt is tensioned and anchored, the compensation spring is in a compressed state. The visualization device includes a housing and a piston. The housing is connected to the slope end baffle, and the piston is connected to the outer end baffle. The piston is slidably connected in the housing, forming a display cavity between the two. Multiple carrier cavities are spaced apart on the housing along the axial direction of the anchor rod. The carrier cavities contain different colored indicator materials. The piston slides to drive the carrier cavities to communicate with or disconnect from the display cavity. In this assessment method: the logarithmic spiral surface failure mechanism is used to describe the slope sliding surface, and a slope stability assessment model is constructed; the spatial arrangement parameters of the anchor bolts are obtained, and the anchor bolt prestress loss coefficient is obtained through a visualization device; the safety factor of the slope under the current anchor bolt reinforcement condition is obtained by iterative solution. The slope stability assessment model is based on the balance between the work done by external forces and the dissipation of internal energy, and the relationship is as follows: ； In the formula, This indicates the power of the work done by the weight of the sliding soil. This represents the power dissipated within the smooth surface. This indicates the external force power provided by the anchor bolt reinforcement; ； In the formula, Indicates the weight of soil and rock. It is the angular velocity of the sliding body; The first integral factor is related to the slope geometry and the anchor bolt position. This is the second integral factor related to the slope geometry and anchor bolt location. The third integral factor is related to the slope geometry and anchor position; ； In the formula, The slope inclination angle is... This represents the distance from the center of rotation O to the starting point A of the sliding motion at the top of the slope; The starting angle of the logarithmic spiral, The terminal angle of the logarithmic spiral, the most dangerous slip surface. and Determined through code search. Indicates the internal friction angle of rock and soil; Reduced cohesion satisfy , It is cohesive force; This is a reduction factor, reflecting the stability of the slope under the current anchor reinforcement conditions; simultaneously, the reduced friction angle... satisfy: ; ； In the formula, This indicates the ultimate bearing capacity of the prestressed anchor. This indicates the anchor bolt prestress locking value. Indicates the polar radius of the anchorage point. This represents the polar angle of the anchor point in polar coordinates. Indicates the anchorage angle of the anchor bolt. The prestress loss coefficient of the anchor bolt is roughly determined by reading the color of the color indicator material in the display cavity.

2. The slope stability assessment method based on an anchor bolt visualization device according to claim 1, characterized in that: The housing is also provided with a plurality of partition components at intervals, and the partition components are disposed between two adjacent carrier cavities; the partition components include a partition spring and a partition plate, the partition plate is slidably connected to the housing in the radial direction of the housing, and the partition spring is used to drive the partition plate to insert into the display cavity to separate the display cavity.

3. The slope stability assessment method based on an anchor bolt visualization device according to claim 2, characterized in that: The housing is also provided with a frame, the partition assembly is disposed inside the frame, one end of the partition spring abuts against the partition plate, and the other end abuts against the top wall inside the frame.

4. The slope stability assessment method based on an anchor bolt visualization device according to claim 3, characterized in that: The logarithmic spiral surface failure mechanism describes the slope sliding surface, and its curve equation is given by the angle of inclination. The expression: ； ； In the formula, This represents the polar radius from any point on the logarithmic spiral to the center of rotation O. This represents the distance from the center of rotation O to the starting point A of the sliding motion at the top of the slope. Indicates the internal friction angle of rock and soil; The starting angle of the logarithmic spiral, The terminal angle of the logarithmic spiral, the most dangerous slip surface. and Determined by searching the calculation code; H represents the slope height.

5. The slope stability assessment method based on an anchor bolt visualization device according to claim 4, characterized in that: The calculation formula is as follows: ； ； ； in This is represented as the slope angle.

6. The slope stability assessment method based on an anchor bolt visualization device according to claim 5, characterized in that: The color indicator materials are incompatible; when one color appears in the display cavity, the anchor bolt prestress loss coefficient ranges from [value missing]. When two colors appear in the display cavity, the range of the anchor bolt prestress loss coefficient is: ; When three colors appear in the display cavity, the range of the anchor bolt prestress loss coefficient is: The precise values ​​are determined based on the pre-established calibration relationship between piston displacement and prestress loss coefficient.

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