A Design Method for Anchor Cable Reinforcement of High-Steep Weathered Road Cutting Slopes

Abstract

The present invention provides a design method for cable anchor reinforcement of a high-steep weathered cutting slope, and the steps include: S1: obtaining the thickness h of the strongly weathered layer; S2: obtaining the parameters γ, c and #imgabs0# of the strongly weathered layer; S3: specifying the designed slope angle β of the slope, as well as the spatial spacing S of the cable anchors y and S z , where S y is the horizontal spacing of the cable anchors, and S z is the vertical spacing of the cable anchors; S4: establishing a correlation formula between the cable anchor force and the cable anchor inclination angle by using the sliding law of the weathered slope and the cable anchor force; S5: according to the construction range [δ1, δ2] of the cable anchor inclination angle in the actual project, and combining the correlation formula between the cable anchor force and the cable anchor inclination angle, obtaining the optimal design value δ of the cable anchor inclination angle when the cable anchor force is theoretically the largest optimal ; S6: after determining the cable anchor inclination angle, establishing a correlation formula between the slope safety factor and the cable anchor prestress by using the sliding law of the weathered slope again, and obtaining the required cable anchor prestress P when the predetermined safety factor is reached. The method provided by the present invention can simply and quickly determine the optimal design parameters of the cable anchors.

Description

Technical Field

[0001] The present invention relates to the technical field of anchor cable reinforcement design, and particularly to a design method for anchor cable reinforcement of high-steep weathered cutting slopes. Background Art

[0002] In order to maintain the stability of high-steep weathered cutting slopes during construction and later operation, the grid beam prestressed anchor cable system is one of the effective reinforcement measures for them. By bundling the deep stable rock mass with the surface unstable rock mass through the anchor cable, the purpose of stabilizing the surface unstable rock mass is achieved. When prestress is applied to the anchor cable, the slope is actively given an anchoring force. Thus, active protection is formed for the slope in advance, further improving the deformation and stability conditions of the slope. Facts have also proved that the grid beam prestressed anchor cable system has a good effect on avoiding and preventing slope landslide disasters. In order to achieve the maximum efficiency of anchor cable reinforcement, it is necessary to optimize the design of anchor cable parameters. The design parameters of the anchor cable include the prestress applied to it, the layout spacing, and the inclination angle. Currently, the following several methods are mainly used for the design of anchor cable parameters: (1) The engineering analogy method, which determines the reasonable design parameters of the anchor cable by analyzing and comparing with existing similar engineering cases; (2) The theoretical or numerical simulation method based on stability analysis, which establishes the same theoretical or numerical model for the existing engineering project, and then within the reasonable range of the anchor cable design parameters, searches for the combination of anchor cable design parameters that maximizes the safety factor of the slope. However, among the above methods, the anchor cable design parameters obtained by the engineering analogy method are relatively reliable, but they are not necessarily the best; the theoretical or numerical simulation method based on stability analysis can make the stability of the reinforced slope reach the optimal, but its process is relatively cumbersome and requires multiple repeated calculations to search for the optimal value, so it is time-consuming and inefficient. In addition, if conditions (such as the slope shape, rock and soil strength parameters, etc.) change, the theoretical or numerical simulation method has to be recalculated repeatedly, so the operability and simplicity of this method are not strong.

[0003] Therefore, there is an urgent need for a design method for anchor cable reinforcement of high-steep weathered cutting slopes, which can simply and quickly determine the optimal design parameters of the anchor cable. Summary of the Invention

[0004] The main purpose of the present invention is to provide a design method for anchor cable reinforcement of high-steep weathered cutting slopes, aiming to solve the technical problems that the acquisition of the design parameters of the anchor cable for high-steep weathered cutting slopes is complex and the optimality cannot be guaranteed.

[0005] To achieve the above purpose, the present invention provides a design method for anchor cable reinforcement of high-steep weathered cutting slopes,

[0006] and its steps include:

[0007] S1: Obtain the thickness h of the strongly weathered layer;

[0008] S2: Obtain the parameters γ, c of the highly weathered layer and where γ is the unit weight of the rock and soil mass in the highly weathered layer, c is the cohesion of the rock and soil mass in the highly weathered layer, and is the internal friction angle of the rock and soil mass in the highly weathered layer;

[0009] S3: Specify the designed slope angle β of the slope and the spatial spacing S of the anchor cables y and S z , where S y is the horizontal spacing of the anchor cables, and S z is the vertical spacing of the anchor cables;

[0010] S4: Establish the correlation formula between the anchor cable anchoring force and the anchor cable dip angle by using the sliding law of the weathered slope and the anchor cable anchoring force;

[0011] S5: According to the construction range [δ1, δ2] of the anchor cable dip angle in the actual project and in combination with the correlation formula between the anchor cable anchoring force and the anchor cable dip angle, obtain the optimal design value δ of the anchor cable dip angle when the anchor cable anchoring force is theoretically the largest optimal ;

[0012] S6: After determining the anchor cable dip angle, establish the correlation formula between the slope safety factor and the anchor cable prestress by using the sliding law of the weathered slope again, and obtain the required anchor cable prestress P when the predetermined safety factor is reached.

[0013] As a further improvement of the above solution, the correlation formula between the anchor cable anchoring force and the anchor cable dip angle is specifically shown in Equation (1):

[0014]

[0015] where, is the anchoring force, S l is the spacing on the vertical slope surface, and P is the prestress applied to the anchor cable.

[0016] As a further improvement of the above solution, the steps to obtain the optimal design value δ of the anchor cable dip angle when the anchor cable anchoring force is theoretically the largest are as follows: optimal :

[0017] First, use the mathematical method of finding extreme values to take the derivative of the correlation formula between the anchor cable anchoring force and the anchor cable dip angle, and the derivative formula of the anchor cable anchoring force per unit length and the anchor cable dip angle is specifically shown in Equation (2):

[0018]

[0019] Then set Equation (2) equal to 0, and the optimal dip angle δ of the anchor cable when the anchor cable anchoring force per unit length is theoretically the largest can be obtained optimal , and

[0020] As a further improvement of the above solution, in step S5, within the construction range [δ1, δ2] of the anchor cable inclination angle, the process of searching for the anchor cable inclination angle δ is as follows:

[0021] If δ optimal ≧δ1 and δ optimal ≦δ2, then δ = δ optimal ; otherwise, further determine whether δ optimal is less than δ1. If so, then δ = δ1; otherwise, δ = δ2, thereby obtaining the anchor cable inclination angle δ.

[0022] As a further improvement of the above solution, the specific formula (3) for the correlation between the slope safety factor and the anchor cable prestress is as follows:

[0023]

[0024] where F S is the safety factor,

[0025] As a further improvement of the above solution, in step S1, the thickness h of the strongly weathered layer is obtained through geological exploration.

[0026] As a further improvement of the above solution, in step S2, the parameters γ, c of the strongly weathered layer are obtained through laboratory tests and

[0027] As a further improvement of the above solution, the method for obtaining the correlation formula between the anchor cable anchoring force and the anchor cable inclination angle is as follows:

[0028] Perform a mechanical analysis on the three-dimensional anchored strip column. The forces acting on it are: gravity W, shear force T on the slip surface, normal force N on the slip surface, and anchor cable prestress P;

[0029] The anchoring force formed by the prestress applied to the anchor cable on the strip column includes two parts. One is the anti-slip friction force provided in the direction perpendicular to the slope slip surface, and the other is the anti-slip force Pcos(β + δ) parallel to the slope slip surface. is the internal friction angle of the strongly weathered layer rock and soil mass.

[0030] The specific formula for the anchoring force provided by the anchor cable per unit length in the three-dimensional anchored strip column is as follows:

[0031]

[0032] where L is the length of the anchor cable in the strongly weathered layer, and L = h / cosβ.

[0033] As a further improvement of the above solution, the method for obtaining the slope safety factor F s is as follows:

[0034] After the inclination angle δ of the anchor cable is determined, according to the sliding law of the high-steep weathered slope and based on the mechanical analysis of the three-dimensional anchored strip column without considering the inter-strip force, it can be known that the weight of the strip column W = γhS y S z / cosβ, the normal force of the sliding surface The shear force T of the sliding surface = γhS y S z tanβ - Pcos(β + δ), thus obtaining the calculation formula of the slope safety factor F s is specifically as follows:

[0035]

[0036] Since the present invention adopts the above technical solutions, the beneficial effects of the present application are as follows:

[0037] The present invention provides a design method for anchor cable reinforcement of high-steep weathered cutting slopes. First, using the sliding law of the weathered slope and the anchoring force of the anchor cable, an association formula between the anchoring force of the anchor cable and the inclination angle of the anchor cable is established; then, according to the construction range [δ1, δ2] of the inclination angle of the anchor cable in the actual project and in combination with the association formula between the anchoring force of the anchor cable and the inclination angle of the anchor cable, the optimal design value δ of the inclination angle of the anchor cable when the anchoring force of the anchor cable is theoretically the largest is obtained optimal ; then, after determining the inclination angle of the anchor cable, using the sliding law of the weathered slope again, an association formula between the slope safety factor and the prestress of the anchor cable is established, and the required prestress P of the anchor cable when the predetermined safety factor is reached is obtained; such a setting makes the most of the sliding law of the weathered slope and the reasonable requirements of anchor cable construction and slope stability, and can effectively and quickly determine the optimal inclination angle of the anchor cable and the prestress value to be applied, thereby providing a basis for the optimal design of the slope grid beam prestressed anchor cable system and having a low implementation cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0039] Figure 1 Schematic diagram of three-dimensional anchor cable reinforcement of high-steep weathered cutting slope for the embodiment of the present invention;

[0040] Figure 2 Schematic diagram of two-dimensional section of anchor cable reinforcement of high-steep weathered cutting slope for the embodiment of the present invention ( Figure 1 section A-A in);

[0041] Figure 3 Schematic diagram of force analysis of a three - dimensional anchored strip column and its two - dimensional cross - section under the action of a cable in an embodiment of the present invention;

[0042] Figure 4 Schematic diagram of the cosine curve related to the cable inclination angle and the optimal cable inclination angle when the anchoring force is maximum in an embodiment of the present invention

[0043] Figure 5 Optimal reinforcement design flow chart of a cable for a high - steep weathered cutting slope in an embodiment of the present invention.

[0044] Reference numerals:

[0045] 1. High - steep weathered cutting slope; 2. Strongly weathered layer; 3. Grid beam; 4. Cable; 5. Main sliding surface; 6. Anchored strip column; 7. Free section of cable; 8. Anchored section of cable.

[0046] The realization, functional features and advantages of the object of the present invention will be further described in conjunction with the embodiments with reference to the drawings. Specific embodiments

[0047] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0048] It should be noted that all directional indications (such as up, down...) in the embodiments of the present invention are only used to explain the relative position relationship and movement conditions between components in a specific posture (as shown in the drawings). If the specific posture changes, the directional indications will also change accordingly.

[0049] The technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can achieve it. When the combination of technical solutions results in contradictions or cannot be achieved, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0050] Refer to Figure 5 , the present invention provides a cable reinforcement design method for a high - steep weathered cutting slope, and its steps include:

[0051] S1: Obtain the thickness h of the strongly weathered layer 2 through geological survey; specifically, according to the requirements of the "Geotechnical Engineering Survey Code" (GB50021-2018) and the "Highway Engineering Geological Survey Code" (JTG C20-2016), the thickness of the strongly weathered layer 2 at the project site shall be ascertained through geological survey;

[0052] S2: Obtain rock mass parameters γ, c and Where γ is the gravity of the strongly weathered layer 2 rock and soil mass, c is the cohesion of the strongly weathered layer 2 rock and soil mass, is the internal friction angle of the strongly weathered layer 2 rock and soil mass;

[0053] S3: Given the slope design angle β and the anchor cable 4 spacing S y and S z , where S y is the horizontal spacing of the anchor cables 4, S z Specifically, according to the requirements of the Technical Specification for Building Slope Engineering (GB 50330-2013), the arrangement spacing (S y and S z );

[0054] S4: Given the construction inclination range [δ1, δ2] of anchor cable 4, specifically, according to the requirements of Technical Code for Building Slope Engineering (GB 50330-2013), determine the reasonable construction range [δ1, δ2] of the anchor cable inclination;

[0055] S5: Predetermined safety factor F of the slope after reinforcement with given prestressed anchor cable 4 S Specifically, the number of grades, platform width, slope reduction ratio and slope stability requirements under long-term conditions (i.e. the slope safety factor needs to reach a certain value) of high and steep cutting slopes shall be determined in accordance with the requirements of the Technical Code for Construction Slope Engineering (GB 50330-2013);

[0056] S6: Calculate the optimal inclination angle δ of anchor cable 4 when the anchoring force is maximum in theory according to the correlation formula between anchor cable anchoring force and anchor cable inclination angle optimal ;

[0057]

[0058] The anchoring force S l is the spacing on the vertical slope surface, and P is the prestress applied to the anchor cable 4;

[0059] S7: If δ optimal ≧δ1, and δ optimal ≦δ2, then δ=δ optimal Otherwise, judge δ optimalWhether it is less than δ1. If so, δ = δ1; otherwise, δ = δ2, so as to obtain the construction dip angle δ;

[0060] S8: Calculate the prestress P of the cable anchor 4 required to make the slope reach the predetermined safety factor according to the correlation formula between the slope safety factor and the prestress of the cable anchor 4.

[0061]

[0062] where

[0063] With such a setting, the sliding law of the weathered slope and the reasonable construction requirements of the cable anchor 4 and the slope stability requirements are utilized to the greatest extent, and the optimal dip angle and the prestress value to be applied of the cable anchor 4 can be effectively and quickly determined, thereby providing a basis for the optimal design of the prestressed cable anchor 4 system of the slope grid beam 3, and the implementation cost is low.

[0064] As a preferred embodiment, the steps to obtain the optimal design value δ of the cable anchor dip angle when the theoretical cable anchor anchoring force is the largest are as follows: optimal are as follows:

[0065] First, use the mathematical method of finding extreme values to take the derivative of the correlation formula between the cable anchor anchoring force and the cable anchor dip angle, and the derivative formula of the cable anchor anchoring force per unit length and the cable anchor dip angle is specifically shown in Equation (2):

[0066]

[0067] Then make Equation (2) equal to 0, and the optimal dip angle δ of the cable anchor 4 when the theoretical cable anchor anchoring force per unit length is the largest can be obtained. optimal and

[0068] As a preferred embodiment, the method for obtaining the correlation formula between the cable anchor anchoring force and the cable anchor dip angle is as follows:

[0069] Conduct a mechanical analysis on the three-dimensional anchored strip column 6. The forces acting on it are: gravity W, shear force T on the slip surface, normal force N on the slip surface, and prestress P of the cable anchor 4;

[0070] The anchoring force formed by the prestress applied on the cable anchor 4 to the strip column includes two parts. One is the anti-slip friction force provided in the direction perpendicular to the slope slip surface. The other is the anti-slip force Pcos(β + δ) parallel to the slope slip surface. is the internal friction angle of the rock and soil mass of the strongly weathered layer 2.

[0071] The calculation formula for the anchoring force provided by the cable anchor 4 per unit length in the three-dimensional anchored strip column 6 is specifically as follows:

[0072]

[0073] Wherein, L is the length of the anchor cable 4 in the highly weathered layer 2, and L = h / cosβ.

[0074] As a preferred embodiment, the slope safety factor F s is obtained as follows:

[0075] After the inclination angle δ of the anchor cable is determined, according to the sliding law of the high-steep weathered slope and based on the mechanical analysis of the three-dimensional anchored strip column 6 without considering the inter-strip force, it can be known that the weight of the strip column W = γhS y S z / cosβ, the normal force on the slip surface The shear force T on the slip surface = γhS y S z tanβ - Pcos(β + δ), thereby obtaining the calculation formula of the slope safety factor F s is specifically as follows:

[0076]

[0077] It should be noted that, as Figure 1 shown, for the high-steep weathered cutting slope 1, during its excavation formation process, the slope is usually disposed in levels ( Figure 1 is a 3-level and 2-step disposal method). In the high-steep weathered cutting slope 1, the weathering effect weakens successively from the slope surface to the deep part. Therefore, the highly weathered layer 2, moderately weathered layer, slightly weathered layer, and unweathered layer are distributed successively from the shallow layer to the deep layer inside the slope. The rock and soil mass of the highly weathered layer 2 is much weaker in shear strength than that of the moderately weathered layer, slightly weathered layer, and unweathered layer, and the interface between the highly weathered layer 2 and the moderately weathered layer is approximately parallel to the slope surface. In order to maintain the long-term stability of the high-steep weathered cutting slope 1, a grid beam 3 prestressed anchor cable 4 system is used to reinforce it. For the grid beam 3 prestressed anchor cable 4 system, it includes two parts: the grid beam 3 and the anchor cable 4. Among them, the anchor cable 4 part is the main measure for active protection of the slope, and the design of the grid beam 3 prestressed anchor cable 4 system is often the design of the anchor cable 4 parameters. For the anchor cable 4 parameters, they include the horizontal and vertical spacings, inclination angle, and the prestress value applied to the anchor cable 4. For the prestress applied to the anchor cable 4, it needs to be borne by the anchor cable anchorage section 8 in the stable rock mass inside the slope, and the unstable rock mass of the slope is tied to the stable rock mass by the free section 7 of the anchor cable to achieve the purpose of stabilizing the slope. For the spacing of the anchor cables 4, when establishing the xyz-axis coordinate system in the three-dimensional high-steep weathered cutting slope 1, the horizontal spacing of the anchor cables 4 is S y and the spacing on the vertical slope surface is S l .

[0078] To better illustrate the inventive concept of the present invention, the following will be described in conjunction with specific embodiments. Specifically, a high and steep weathered cut slope 1 with a designed slope height of 50 m is selected, sloped at a ratio of 1:1 (i.e., a slope angle of 45°), and provided with 4 steps and 5 levels of slopes, with each level of slope having a height of 10 m. According to geological surveys and drilling disclosures, the underlying bedrock of this section of the slope is mainly strongly and moderately weathered phyllite and phyllitic slate. The thickness of the strongly weathered layer 2 is between 2 m and 4 m, and this layer has well-developed joints and fractures, and the rock mass is relatively fragmented, being the main unstable rock mass. For the rock mass of the strongly weathered layer 2, its natural unit weight is 25 kN / m3, the cohesion is approximately 15 kPa, and the internal friction angle is approximately 35°. To ensure the stability of this high and steep weathered cut slope 1 during construction and subsequent operation, a grid beam 3 prestressed anchor cable 4 system is constructed to reinforce the slope. While adopting the grid beam 3 prestressed anchor cable 4 system for reinforcement, an optimization calculation of the parameters of the prestressed anchor cable 4 is carried out. The design parameters of the anchor cable 4 include its spacing, inclination angle, and prestress value. Among them, the spacing of the anchor cable 4 is determined according to engineering experience and construction requirements, and then, based on the maximum anchoring force per unit length of the anchor cable and in combination with the reasonable construction range of the inclination angle of the anchor cable in actual projects, the optimal design value of the inclination angle of the anchor cable is determined. Finally, on the basis of using the sliding law of the weathered slope, a correlation formula between the slope safety factor and the prestress of the anchor cable 4 is established, and then the prestress value to be applied to the anchor cable 4 is obtained under the condition of meeting the slope stability requirements (i.e., the slope safety factor reaches a certain value). In addition, to ensure the effectiveness of the reinforcement measures, for the prestressed anchor cable 4, the length of its anchorage section embedded below the corresponding main sliding surface 5 (i.e., the strongly weathered layer 2) is not less than 1 / 4 of its total length.

[0079] As Figure 2 shown, take Figure 1 a cross-section A-A of the three-dimensional slope in z any plane parallel to the xz plane for analysis. In the high and steep weathered cut slope 1, the slope angle is β, the thickness of the strongly weathered layer 2 is h, and the inclination angle is approximately β. The vertical spacing of the anchor cable 4 is S z and the inclination angle is δ. Since the shear strength of the rock and soil mass in the strongly weathered layer 2 is much weaker than that of the moderately weathered layer, weakly weathered layer, and unweathered layer below it, the main sliding surface 5 of the high and steep weathered cut slope 1 is the interface between the strongly weathered layer 2 and the moderately weathered layer.

[0080] For a single anchor cable 4, the main unstable rock mass it reinforces is the vertical strip column (i.e., the anchored strip column 6) within the spacing range of the anchor cable 4. For the anchored strip column 6, its widths in the y and z axis directions are Sy and Sz respectively. The bottom surface of the strip column is the interface between the strongly weathered layer 2 and the moderately weathered layer. The length of the anchor cable 4 in the strongly weathered layer 2 is L, L = h / cosβ, and the prestress applied to the anchor cable 4 is P.

[0081] As Figure 3As shown in the figure, a mechanical analysis is carried out on the three-dimensional anchor strip column 6. The forces acting on it are: gravity W, shear force T on the slip surface, normal force N on the slip surface, and prestress P of the anchor cable 4. The anchoring force formed by the prestress applied on the anchor cable 4 on the strip column consists of two parts. One is the anti-sliding friction force provided in the direction perpendicular to the slope slip surface The other is the anti-sliding force Pcos(β + δ) parallel to the slope slip surface. is the internal friction angle of the rock and soil mass in the highly weathered layer 2. Thus, the calculation formula for the anchoring force provided by the anchor cable 4 per unit length in the three-dimensional anchor strip column 6 is as follows:

[0082]

[0083] Then, using the mathematical method of finding the extreme value, the derivative formula of the anchoring force of the anchor cable per unit length and the inclination angle of the anchor cable is as follows:

[0084]

[0085] Taking the derivative formula equal to 0, that is the optimal inclination angle δ of the anchor cable 4 when the anchoring force of the anchor cable per unit length is theoretically the largest can be obtained optimal , and

[0086] As Figure 4 shown, in actual engineering, 0 < β ≤ π / 2, 0 ≤ δ ≤ π / 4. Thus, it can be seen that Furthermore, within this range, the positive and negative relationship between the derivative of the anchoring force of the anchor cable per unit length and the inclination angle of the anchor cable shows that the anchoring force of the anchor cable per unit length first increases and then decreases as the inclination angle of the anchor cable increases. At the same time, the anchoring force of the anchor cable per unit length will reach the maximum. Within the reasonable construction range of the inclination angle of the anchor cable, the closer the inclination angle of the anchor cable is to δ optimal , the greater the efficiency of the anchoring force of the anchor cable per unit length will be.

[0087] As Figure 5 shown, for the inclination angle of the anchor cable, its reasonable construction range is [δ1, δ2]. From the variation relationship between the inclination angle of the anchor cable and the anchoring force of the anchor cable per unit length (i.e., Figure 5 the cosine curve in optimal ), it can be seen that if δ optimal is within the range of [δ1, δ2], then the optimal inclination angle of the anchor cable 4 is δ optimal If δ is on the left side outside the range of [δ1, δ2], then the optimal inclination angle of the anchor cable 4 is δ1. If δ optimalOn the right side outside the range of [δ1, δ2], the optimal inclination angle of the anchor cable 4 is δ2. After determining the inclination angle of the anchor cable, again according to the sliding law of the high-steep weathered slope and based on the mechanical analysis of the three-dimensional anchored strip column 6 without considering the inter-strip force, it can be known that the weight of the strip column W = γhSySz / cosβ, the normal force of the sliding surface The shear force of the sliding surface T = γhSySztanβ - Pcos(β + δ), and the calculation formula of the slope safety factor Fs is as follows:

[0088]

[0089] γ is the unit weight of the rock and soil mass in the strongly weathered layer 2, and c is the cohesion of the rock and soil mass in the strongly weathered layer 2. Further, when the slope stability requirements are met (that is, the slope safety factor reaches a certain value), the correlation formula between the slope safety factor and the prestress of the anchor cable 4 can be obtained.

[0090] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structural transformation made by using the content of the specification and drawings of the present invention under the inventive concept of the present invention, or direct / indirect application in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A design method for cable anchor reinforcement of a high-steep weathered cutting slope, characterized in that, The steps include: S1: Obtain the thickness h of the strongly weathered layer; S2: Obtain the parameters γ, c of the strongly weathered layer and where γ is the unit weight of the rock and soil mass in the strongly weathered layer, c is the cohesion of the rock and soil mass in the strongly weathered layer, and is the internal friction angle of the rock and soil mass in the strongly weathered layer; S3: Given the designed slope angle β of the slope and the spatial spacing S of the anchor cables y and S z , where S y is the horizontal spacing of the anchor cables, and S z is the vertical spacing of the anchor cables; S4: Utilize the sliding law of the weathered slope and the anchoring force of the cable anchor to establish the correlation formula between the anchoring force of the cable anchor and the inclination angle of the cable anchor, specifically as shown in Equation (1): Among them, is the anchoring force, S l is the spacing on the vertical slope of the cable bolt, and P is the prestress applied to the cable bolt; S5: According to the construction range [δ1, δ2] of the cable anchor inclination angle in the actual project, and combined with the correlation formula between the cable anchor anchoring force and the cable anchor inclination angle, obtain the optimal design value δ of the cable anchor inclination angle when the cable anchor anchoring force is theoretically the largest optimal , obtain the optimal design value δ of the cable anchor inclination angle when the cable anchor anchoring force is theoretically the largest optimal The steps are as follows: First, use the mathematical method of finding the extreme value to take the derivative of the correlation formula between the anchoring force of the cable anchor and the inclination angle of the cable anchor, and the derivative formula of the anchoring force per unit length of the cable anchor with respect to the inclination angle of the cable anchor is specifically as shown in Equation (2): Then, by setting formula (2) equal to 0, the optimal inclination angle δ of the anchor cable when the anchoring force per unit length is theoretically maximized can be obtained. optimal , and Within the construction range [δ1, δ2] of the inclination angle of the cable anchor, the process of searching for the inclination angle δ of the cable anchor is as follows: If δ optimal ≥ δ1, and δ optimal ≤ δ2, then δ = δ optimal ; Otherwise, determine again whether δ optimal is less than δ1. If so, δ = δ1; otherwise, δ = δ2, thereby obtaining the cable anchor inclination angle δ; S6: After determining the inclination angle of the cable anchor, once again utilize the sliding law of the weathered slope to establish the correlation formula between the slope safety factor and the prestress of the cable anchor, and obtain the required prestress P of the cable anchor when reaching the predetermined safety factor. The correlation formula (3) between the slope safety factor and the prestress of the cable anchor is specifically as follows: where F S is the safety factor, 2. The design method for cable anchor reinforcement of a high-steep weathered cutting slope according to claim 1, characterized in that The method for obtaining the correlation formula between the anchoring force of the cable anchor and the inclination angle of the cable anchor is as follows: Conduct a mechanical analysis on the three-dimensional anchored strip column. The forces acting on it are: gravity W, shear force T on the sliding surface, normal force N on the sliding surface, and prestress P of the cable anchor; The prestress applied to the cable anchor generates an anchoring force on the strip column, which consists of two parts. One is the anti-sliding frictional force provided perpendicular to the slope sliding surface. The other is the anti-sliding force Pcos(β + δ) parallel to the slope sliding surface. φ is the internal friction angle of the rock and soil mass in the strongly weathered layer. The calculation formula for the anchoring force provided by the cable anchor per unit length within the three-dimensional anchored strip column is specifically as follows: Among them, L is the length of the cable anchor within the strongly weathered layer, and L = h / cosβ.

3. A design method for anchor cable reinforcement of a high-steep weathered cutting slope according to claim 1, characterized in that, The safety factor F of the slope s is obtained as follows: After the inclination angle δ of the anchor cable is determined, according to the sliding law of the high-steep weathered slope and based on the mechanical analysis of the three-dimensional anchored strip column without considering the inter-strip force, it can be known that the weight of the strip column W = γhS y S z / cosβ, the normal force of the sliding surface The shear force of the sliding surface T = γhS y S z tanβ - Pcos(β + δ), and then the calculation formula of the slope safety factor F s is as follows specifically:

4. A design method for cable anchor reinforcement of a high-steep weathered cutting slope according to claim 1, characterized in that, In step S2, the parameters γ, c of the strongly weathered layer are obtained through laboratory tests and 5. A design method for cable anchor reinforcement of a high-steep weathered cutting slope according to claim 1, characterized in that, In step S1, obtain the thickness h of the strongly weathered layer through geological exploration.

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