Calculation method of stability against sliding of gravity dam considering lateral rock mass resistance

Abstract

The application discloses a kind of considering lateral rock mass resistance gravity dam anti-sliding stability calculation method, including ① determining base surface boundary line and dam section joint line ② carry out anti-sliding stability calculation: according to field survey, the intersection of weak interlayer in the lateral rock mass of bank slope dam section and base surface boundary line is determined, with the plane where weak interlayer is located as the calculation sliding surface, considering the area proportion relationship between the intersection of the plane where weak interlayer is located and base surface and the area of concrete in sliding surface of this dam section, the comprehensive weighted cohesion at sliding surface is obtained by weighted average calculation;Sliding surface friction coefficient is according to weak interlayer friction coefficient value;Finally, the anti-sliding stability safety factor of this dam section at sliding surface is calculated ③ according to the anti-sliding stability safety factor obtained, determine the treatment scheme to weak interlayer.The application can reduce the workload such as excavating weak interlayer in part of dam section range and reinforcing treatment to base surface, save engineering investment, shorten engineering construction period.

Description

Technical Field

[0001] This invention relates to the field of gravity dam construction technology, and in particular to a method for calculating the anti-sliding stability of gravity dams that takes into account the lateral rock mass resistance. Background Technology

[0002] In gravity dam engineering, the selection of the foundation surface is of great technical and economic significance, and is a crucial yet frequently controversial issue. The excavation depth of the foundation affects the dam's anti-sliding stability, safety, workload, and investment. During project implementation, surface geological defects in the foundation are typically addressed through excavation followed by consolidation grouting. Deeply buried weak interlayers are usually treated by excavation followed by concrete replacement and the installation of deep grooves. However, for weak interlayers located beneath the foundation surface on the dam slope, traditional excavation and replacement methods present challenges such as construction difficulties, increased investment, and extended construction periods. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a method for calculating the anti-sliding stability of gravity dams that considers lateral rock mass resistance, specifically employing the following technical solution:

[0004] The gravity dam anti-sliding stability calculation method considering lateral rock mass resistance described in this invention includes...

[0005] The first step is to determine the foundation surface edge line and dam section joint line according to the gravity dam design scheme;

[0006] The second step is to perform anti-sliding stability calculations: Based on the on-site survey, the intersection point of the weak interlayer in the lateral rock mass of the dam section and the edge of the foundation surface is determined. The surface where the weak interlayer is located is taken as the calculation sliding surface. Considering the ratio of the area of ​​the lateral rock mass of the dam section at the intersection point between the weak interlayer and the foundation surface to the area of ​​the concrete in that dam section at the sliding surface, a weighted average is used to calculate the comprehensive weighted cohesion at the sliding surface. The friction coefficient of the sliding surface is taken according to the friction coefficient of the weak interlayer. Finally, the anti-sliding stability safety factor of the dam section at the sliding surface is calculated.

[0007] The third step is to determine the treatment plan for the weak interlayer based on the calculated anti-slip stability safety factor.

[0008] 1) The following formula is used to calculate the overall weighted cohesion in the second step:

[0009] (1)

[0010] In the formula:

[0011] —The overall weighted cohesion at the sliding surface, in MPa;

[0012] A – Area of ​​the sliding surface contact zone, m 2 ;

[0013] —Cohesion of the rock mass on the inner side of the dam section, MPa;

[0014] A1—Lateral rock mass area at the sliding surface within the dam section, in m³ 2 ;

[0015] — Concrete cohesion within the dam section, MPa;

[0016] A2—The area occupied by concrete at the sliding surface within the dam section, in meters. 2 ;

[0017] 2) The friction coefficient is calculated in the second step using the following formula:

[0018] (2)

[0019] In the formula:

[0020] —Coefficient of shear friction at the sliding surface;

[0021] —Coefficient of shear friction of weak interlayer;

[0022] 3) In the second step, the anti-sliding stability safety factor of the dam section at the sliding surface is calculated using the rigid body limit equilibrium method by comprehensively considering the weighted cohesion and friction coefficient, and the following formula is adopted:

[0023] (3)

[0024] In the formula:

[0025] —Safety factor for anti-sliding stability calculated based on shear strength;

[0026] — The sum of the components of all loads acting on the dam body in the direction perpendicular to the plane containing the weak interlayer, kN;

[0027] —The sum of the components of all loads acting on the dam body in the direction along the plane where the weak interlayer is located, kN;

[0028] In the third step, when the anti-slip stability safety factor The foundation surface selection meets the requirements, and no further treatment is needed for the weak interlayer; when the anti-slip stability safety factor is within At that time, based on the actual excavation findings, the method of excavating shallow, weak interlayers and supplementing them with consolidation grouting was selected for treatment; when the anti-sliding stability safety factor was... In this case, a deep toothed groove is selected to cut off the weak interlayer, and concrete replacement is used for treatment.

[0029] The advantage of this invention is that when performing anti-sliding stability calculations, the cohesive force of the rock mass between the dam section side and the weak interlayer is considered, and the lateral rock mass resistance is utilized. The shear resistance parameters at the elevation of the weak interlayer are weighted and averaged, thereby reducing the workload of excavating the weak interlayer within the dam section and reinforcing the foundation surface, saving project investment and shortening the project period. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the distribution of weak interlayers in the bank slope dam section of this invention. Detailed Implementation

[0031] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. These embodiments are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operation processes are given. However, the scope of protection of the present invention is not limited to the following embodiments.

[0032] like Figure 1 As shown, the gravity dam anti-sliding stability calculation method considering lateral rock mass resistance according to the present invention includes:

[0033] The first step is to determine the foundation surface edge line and the dam section division lines according to the gravity dam design scheme. In this embodiment, the foundation surface edge line 1 of the bank slope dam section is a broken line. The lower left side of the foundation surface edge line 1 is rock mass 2, and the upper right side is gravity dam 3. Gravity dam 3 is divided into multiple segments by the division lines 4. Within the rock mass 2, there is a weak interlayer 5, which extends horizontally to the right. Figure 1 The slope at the middle section of the China Construction Base Surface Edge Line 1.

[0034] The second step is to perform anti-skid stability calculations:

[0035] Based on the on-site survey, the intersection point O of the weak interlayer 5 in the lateral rock mass 2 of the bank slope dam section and the edge line 1 of the foundation surface was determined, and the elevation h0 of the weak interlayer was determined by the surface where the weak interlayer 5 is located.

[0036] 1) Considering the ratio of the area A1 of the rock mass on the side of the dam section where the weak interlayer elevation h0 and the foundation surface O intersect within the dam section are located to the area A2 of the concrete in that dam section at the weak interlayer elevation h0, the weighted average is used to calculate the comprehensive weighted cohesion at the sliding surface. The following formula is used in the calculation:

[0037] 1) The following formula is used to calculate the overall weighted cohesion in the second step:

[0038] (1)

[0039] In the formula:

[0040] —The overall weighted cohesion at the sliding surface, in MPa;

[0041] A – Area of ​​the contact surface of the sliding surface, in m³ 2 ;

[0042] —Cohesion of the rock mass on the inner side of the dam section, MPa;

[0043] A1—The lateral rock mass area at the sliding surface within the dam section, in m³ 2 ;

[0044] — Concrete cohesion within the dam section, MPa;

[0045] A2—The area occupied by concrete at the sliding surface within the dam section, in meters. 2 ;

[0046] 2) The friction coefficient is calculated in the second step using the following formula:

[0047] (2)

[0048] In the formula:

[0049] —Coefficient of shear friction at the sliding surface;

[0050] —Coefficient of shear friction of weak interlayer;

[0051] 3) In the second step, the anti-sliding stability safety factor of the dam section at the weak interlayer is calculated using the rigid body limit equilibrium method by comprehensively considering the weighted cohesion and friction coefficient, and the following formula is adopted:

[0052] (3)

[0053] In the formula:

[0054] —Safety factor for anti-sliding stability calculated based on shear strength;

[0055] — The sum of the components of all loads acting on the dam body in the direction perpendicular to the plane containing the weak interlayer, kN;

[0056] —The sum of the components of all loads acting on the dam body in the direction along the plane where the weak interlayer is located, kN;

[0057] The third step is to calculate the anti-slip stability safety factor. The treatment plan for the weak interlayer 5 was determined. Specifically, when the anti-slip stability safety factor... The foundation surface selection meets the requirements, and no further treatment is needed for the weak interlayer; when the anti-slip stability safety factor is within At that time, based on the actual excavation findings, the method of excavating shallow, weak interlayers and supplementing them with consolidation grouting was selected for treatment; when the anti-sliding stability safety factor was... When necessary, a deep groove of a certain width is selected to cut off the weak interlayer, and concrete replacement is used for treatment.

[0058] It should be noted that in the description of this invention, terms such as "front," "rear," "left," "right," "vertical," "horizontal," "inner," and "outer" indicating orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

Claims

1. A method for calculating the anti-sliding stability of a gravity dam considering lateral rock mass resistance, characterized in that: include The first step is to determine the foundation surface edge line and dam section joint line according to the gravity dam design scheme; The second step is to perform anti-sliding stability calculations: Based on the on-site survey, the intersection point of the weak interlayer in the lateral rock mass of the dam section and the edge of the foundation surface is determined. The surface where the weak interlayer is located is taken as the calculation sliding surface. Considering the ratio of the area of ​​the lateral rock mass of the dam section at the intersection point between the weak interlayer and the foundation surface to the area of ​​the concrete in that dam section at the sliding surface, a weighted average is used to calculate the comprehensive weighted cohesion at the sliding surface. The friction coefficient of the sliding surface is taken according to the friction coefficient of the weak interlayer. Finally, the anti-sliding stability safety factor of the dam section at the sliding surface is calculated. The third step is to determine the treatment plan for the weak interlayer based on the calculated anti-slip stability safety factor. in, 1) The following formula is used to calculate the overall weighted cohesion in the second step: （1） In the formula: —The overall weighted cohesion at the sliding surface, in MPa; A – Area of ​​the sliding surface contact zone, m 2 ; —Cohesion of the rock mass on the inner side of the dam section, MPa; A1—Lateral rock mass area at the sliding surface within the dam section, in m³ 2 ; — Concrete cohesion within the dam section, MPa; A2—The area occupied by concrete at the sliding surface within the dam section, in meters. 2 ; 2) The friction coefficient is calculated in the second step using the following formula: （2） In the formula: —Coefficient of shear friction at the sliding surface; —Coefficient of shear friction of weak interlayer; 3) In the second step, the anti-sliding stability safety factor of the dam section at the sliding surface is calculated using the rigid body limit equilibrium method by comprehensively considering the weighted cohesion and friction coefficient, and the following formula is adopted: （3） In the formula: —Safety factor for anti-sliding stability calculated based on shear strength; — The sum of the components of all loads acting on the dam body in the direction perpendicular to the plane containing the weak interlayer, kN; —The sum of the components of all loads acting on the dam body along the plane containing the weak interlayer, kN.

2. The gravity dam anti-sliding stability calculation method considering lateral rock mass resistance according to claim 1, characterized in that: In the third step, when the anti-slip stability safety factor The foundation surface selection meets the requirements, and the weak interlayer no longer needs to be treated; When the anti-slip stability safety factor is At that time, based on the actual excavation and exposure conditions on site, the method of excavating shallow weak interlayers and supplementing them with consolidation grouting was selected for treatment. When the anti-slip stability safety factor In this case, a deep toothed groove is selected to cut off the weak interlayer, and concrete replacement is used for treatment.

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