Embedded pile foundation design method for mountainous area bridge, storage medium and equipment

Abstract

The invention discloses an embedded pile foundation design method for a mountainous area bridge, a storage medium and equipment, and the method comprises the following steps: (1) determining the design position and the embedded type of the embedded pile foundation of the bridge according to the mountain area slope terrain, and constructing a mechanical model of the embedded pile foundation of the mountainous area bridge; (2) initially simulating design parameters of the built-in pile foundation according to the embedded type; (3) according to a stress analysis method, calculating the lateral pressure P of the potential most unfavorable shear-resistant position below the embedded rock stratum interface through the stress of the embedded point; (4) according to a limit equilibrium theory, calculating the rock mass shear resistance T of the potential worst shear resistance area embedded below the rock stratum interface; and (5) judging whether the shear strength T of the rock mass can resist the lateral pressure P. Through stress analysis and a limit equilibrium theory, the embedding depth of the pile foundation and the shear resistance of the rock mass are reasonably determined, and the stability and reliability of the pile foundation under the complex terrain condition are ensured.

Claims

1. A method for designing an embedded pile foundation for a mountain bridge, characterized in that: The steps include: S1. According to the slope terrain of mountainous area, determine the design position and embedded type of bridge embedded pile foundation, and construct the mechanical model of embedded pile foundation of mountainous area bridge; S2. According to the design parameters of the embedded pile foundation, the minimum embedding depth h is determined according to the embedded type of the bridge embedded pile foundation, and H1 is the length of the friction resistance section of the pile foundation side wall; S3. According to the stress analysis method, the lateral pressure P at the most unfavorable shear position below the embedded surface is calculated by the embedded point stress: Where, σ is the stress at the embedding point at the lower end of the pile foundation; h x is the depth of the shear zone at the most unfavorable position, which is taken as 1 / 4 of the minimum embedding depth h; b is the length of the pile foundation side perpendicular to the plane of the bending moment; M is the bending moment at the embedding point at the lower end of the pile foundation; S4. According to the limit equilibrium theory, calculate the shear capacity T of the rock mass in the most unfavorable shear area below the embedded rock layer interface: S5. Determine whether the shear capacity T of the rock mass in the most unfavorable shear resistance area below the embedding surface is greater than the lateral pressure P at the most unfavorable shear resistance position below the embedding surface; If T≥P, determine the length of the embedded pile foundation H=H0; If T<P, it is assumed that the embedded surface moves down by 0.5m, that is, the length H of the embedded pile foundation is increased to H0+0.5m, and steps S2-S5 are repeated.

2. The embedded pile foundation design method for mountain bridges according to claim 1 is characterized in that: Step S2 includes the following steps: If the embedded type is a vertical embedded pile foundation, the minimum length of the embedded pile foundation is H0 = H1 + H2 + h, and the minimum embedded depth h is determined by the following formula: M=M0+F·H1-M f H2=H0-h-H1 Where, M is the bending moment at the embedding point of the lower end of the pile foundation, K is the conversion coefficient of the rock allowable pressure in the horizontal direction according to the rock layer structure, which is 0.5 to 1.0; R is the saturated uniaxial compressive strength of the rock; M0 is the bending moment at the arch foot of the pile foundation; M f is the side friction bending moment of the pile foundation; F is the shear force at the arch foot of the pile foundation; H1 is the length of the side friction section of the pile foundation; H2 is the embedding depth between the lower embedding point of the upper end of the pile foundation embedded in the slope and the embedding point of the lower end of the pile foundation; τ is the allowable friction resistance of the rock mass; d is the side length of the pile foundation in the plane of the bending moment; θ is the angle between the slope and the vertical direction.

3. The embedded pile foundation design method for mountain bridges according to claim 1 is characterized in that: Step S2 includes the following steps: If the embedded type is an arch seat inclined embedded pile foundation, the minimum length of the embedded pile foundation H0=H1+h is determined by the following formula to determine the minimum embedded depth h: E=K1K2R Where, h is the embedding depth from the embedding point at the lower end of the pile foundation; d is the side length of the pile foundation in the plane of bending moment; b is the side length of the pile foundation perpendicular to the plane of bending moment; M0 is the bending moment at the arch foot of the pile foundation; M G is the bending moment of pile foundation under deadweight; Q0 is the shear force at the pile foundation arch foot; H1 is the length of the friction resistance section of the pile foundation side wall; G is the deadweight of the pile foundation; θ′ is the angle between the pile foundation and the horizontal plane; Q f is the end bearing friction; K1 is the safety factor, which is 0.5; K2 is the conversion factor of the rock allowable pressure in the horizontal direction according to the rock formation structure, which is 0.5 to 1.0; R is the saturated uniaxial compressive strength of the rock; M0 and Q0 are given by the design load in the specification. G , G and Q f The calculation formula is as follows: Q f =fbd G=ρgbdH1 Where f is the allowable friction between pile foundation concrete and rock; ρ is the density of pile foundation concrete; and g is the acceleration of gravity.

4. The embedded pile foundation design method for mountain bridges according to any one of claims 2 to 3, characterized in that: In step S4, T=T1+T2; wherein T1 is the shear resistance of the side surface of the rock mass; and T2 is the shear resistance of the bottom surface of the rock mass.

5. The embedded pile foundation design method for mountain bridges according to claim 4 is characterized in that: For vertical embedded pile foundation, the calculation formula of rock side shear capacity T1 and rock bottom shear capacity T2 is: T2=[a+(a+h x tanθ)tanα](a+h x tanθ)τ a=(H0-h)tanθ-d Where α is the rock friction angle; a is the horizontal distance from the embedded point of the pile foundation to the slope surface; l is the horizontal distance from the most unfavorable point of the embedded surface to the slope surface; H0 is the minimum length of the embedded pile foundation; h x is the depth of the shear zone at the most unfavorable position, which is taken as 1 / 4 of the minimum embedding depth h, and θ is the angle between the slope and the vertical direction.

6. The embedded pile foundation design method for mountain bridges according to claim 4 is characterized in that: For the arch seat inclined embedded pile foundation, the calculation formula of the rock side shear capacity T1 and the rock bottom shear capacity T2 is: T2=f·(b+ltan α)l l=h x cosθ′+a+h x sinθ′tanθ′l=h x cosθ′+a+h x sinθ′tanθ′ Where α is the rock friction angle; a is the horizontal distance from the embedded point of the lower end of the pile foundation to the slope surface; l is the horizontal distance from the most unfavorable point of the embedded surface to the slope surface; H1 is the length of the friction resistance section of the pile foundation side wall; θ′ is the angle between the pile foundation and the horizontal plane; h x It is the depth of the shear zone at the most unfavorable position, which is taken as 1 / 4 of the minimum embedding depth h. T=SC In the formula, S is the shear resistance area of ​​the rock mass; C is the design shear strength of the rock mass; The rock mass shear resistance area includes a bottom surface and two side surfaces. For vertical embedded pile foundations and abutment inclined pile foundations: the shear resistance of the rock mass in the most unfavorable shear resistance area is calculated by calculating the sum of the shear resistance of the bottom surface and the side surfaces. The formula is: T=T1+T2 Where T1 is the shear capacity of the side surface of the rock mass; T2 is the shear capacity of the bottom surface of the rock mass.

7. The embedded pile foundation design method for mountain bridges according to claim 1 is characterized in that: The steps of step S5 include: S51. If T is not less than P, determine the length of the embedded pile foundation H=H0; S52. If T is less than P, increase the length H of the embedded pile foundation to H0+0.5m. Assuming that the embedded surface moves down by 0.5m, repeat step S2, correct the bending moment value M of the embedded point and the minimum embedded depth h, and determine the new embedded surface position according to the minimum embedded depth h; according to the new embedded surface position, determine the rock flange width a of the free surface and the length H1 of the side wall constraint section; repeat step S3 to calculate the lateral pressure P at the most unfavorable position below the embedded surface; repeat step S4 to calculate the shear capacity T of the rock mass in the most unfavorable range below the embedded surface; if T is not less than P, determine the length of the embedded pile foundation H=H0+0.5m; if T is less than P, continue to increase the length of the embedded pile foundation H until T is not less than P.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for designing an embedded pile foundation for a bridge in a mountainous area according to any one of claims 1 to 7 are implemented.

9. A computer device comprising a memory, a processor and a computer program, characterized in that: The computer program is stored in a memory and configured to be executable by a processor, and the processor implements the steps of the embedded pile foundation design method for a mountain bridge according to any one of claims 1 to 7 when executing the computer program.

Images