A segmented design calculation method according to axial force distribution of rigid-flexible composite pile

Abstract

The present application relates to the technical field of pile foundation design calculation, and particularly relates to a sectional design calculation method according to axial force distribution of rigid-flexible composite pile, which establishes the change curve of axial force along the depth direction of the pile body of the rigid-flexible composite pile, the change curve of side resistance and end resistance along the depth direction, and the change curve of the bearing capacity of the pile body along the depth direction; in the case that the change curve of the axial force along the depth direction of the pile body is enveloped by the change curve of the side resistance and the end resistance along the depth direction and the change curve of the bearing capacity of the pile body along the depth direction, the pile foundation parameters of the rigid-flexible composite pile are adjusted to make the three curves close to each other and improve the matching coincidence degree of the three curves, and the adjusted pile foundation design parameters are obtained. The present application has the advantages that the traditional pile foundation is overturned in that the upper and lower diameters are equal, the material is single, the calculation is simple and rough, the stress matching degree of the pile body is poor, and the design is unreasonable, and the present application innovatively adopts the fine design and calculation method of curve envelopment, so that the stress rationality and economy of the pile foundation are best.

Description

Technical Field

[0001] This invention relates to the field of pile foundation design and calculation technology, and in particular to a segmented design and calculation method based on the axial force distribution of rigid-flexible composite piles. Background Technology

[0002] like Figure 1 As shown, the current methods for pile foundation design and bearing capacity calculation are relatively simple and crude. The pile foundations are all equal-diameter piles, and their bearing capacity is determined by taking the smaller value between the lateral resistance + end resistance bearing capacity and the pile body strength bearing capacity.

[0003] However, in the existing technology, the matching degree between the axial force of the pile body, the bearing capacity of the side resistance + end resistance, and the strength bearing capacity of the pile body is poor, the pile foundation is subjected to unreasonable stress, and the pile body strength is wasted. In some cases, it exceeds the design requirements by several times, resulting in poor economy. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of the prior art by providing a segmented design calculation method based on the axial force distribution of rigid-flexible composite piles. This method establishes curves along the depth direction for the axial force, lateral resistance and end resistance bearing capacity, and strength bearing capacity of the rigid-flexible composite pile. The curve envelope method is then used to optimize the matching between these three factors, thereby maximizing the rationality and economy of the rigid-flexible composite pile design.

[0005] The objective of this invention is achieved through the following technical solutions: A segmented design calculation method based on the axial force distribution of a rigid-flexible composite pile, wherein the rigid-flexible composite pile is composed of rigid piles and flexible piles, with the rigid piles arranged among the flexible piles, wherein the rigid piles bear the superstructure load, and the flexible piles obtain frictional force from the surrounding soil. The segmented design calculation method is characterized by: establishing curves showing the variation of the axial force along the depth direction, the variation of the side resistance and end resistance along the depth direction, and the variation of the bearing capacity along the depth direction of the rigid-flexible composite pile; and adjusting the pile foundation parameters of the rigid-flexible composite pile when the curves showing the variation of the axial force along the depth direction are enveloped by the curves showing the variation of the side resistance and end resistance along the depth direction and the curves showing the variation of the bearing capacity along the depth direction, so as to make the three curves closer and improve the matching and overlap of the three curves, thereby obtaining the adjusted pile foundation design parameters.

[0006] Based on the axial force curve of the pile body, the axial force distribution of the pile body is segmented along the depth direction of the rigid-flexible composite pile.

[0007] The cross-section of the rigid pile is gradually reduced along the depth direction to match the strength bearing capacity of the pile body with the axial force of the pile body.

[0008] The pile foundation parameters include at least the pile diameter ratio of the rigid pile and the flexible pile, the strength of the rigid pile, and the bonding force between the rigid pile and the flexible pile.

[0009] The curves of the axial force along the depth direction, the side resistance and end resistance along the depth direction, and the bearing capacity along the depth direction of the rigid-flexible composite pile are automatically constructed by inputting pile foundation design parameters and soil layer parameters.

[0010] The soil parameters are divided into several soil layers according to the depth direction, including the soil layer thickness of each soil layer, the side resistance between the pile and the soil, the end resistance, the side resistance coefficient, the end resistance coefficient, and the end resistance folding coefficient.

[0011] The advantages of this invention are: it overturns the shortcomings of traditional pile foundations, such as uniform diameter at the top and bottom, single material, simple and rough calculation, poor stress matching of the pile body, and other unreasonable aspects. It innovatively adopts a refined design and calculation method based on curve envelope, so that the stress rationality and economy of the pile foundation are optimized. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the stress performance of pile foundations along the depth direction in the prior art; Figure 2 This is a schematic diagram of the stress performance of the pile foundation along the depth direction in this invention; Figure 3 This is a schematic diagram of the curve envelope method in this invention. Detailed Implementation

[0013] The features and other related features of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments, so as to facilitate understanding by those skilled in the art: Example: Figures 2 to 3 As shown, in this embodiment, a segmented design calculation method based on the axial force distribution of a rigid-flexible composite pile is used for the design calculation of the rigid-flexible composite pile. This rigid-flexible composite pile is composed of rigid piles and flexible piles, with the rigid piles positioned within the flexible piles. The rigid piles bear the upper load, while the flexible piles obtain frictional force from the surrounding soil. In this embodiment, the rigid piles are preferably steel-core piles, which include a steel pipe and concrete poured and filled inside the steel pipe. The flexible piles are preferably cement-soil mixing piles.

[0014] Combination Figure 2 and Figure 3 As shown, the segmented design calculation method in this embodiment specifically includes the following steps: 1) Establish curves showing the variation of axial force along the depth direction, side resistance and end resistance along the depth direction, and bearing capacity along the depth direction for rigid-flexible composite piles. For example... Figure 3As shown, all three are established in a rectangular coordinate system. The horizontal axis of this rectangular coordinate system represents the bearing capacity at the top of the pile, which increases from the origin of the rectangular coordinate system, representing the bearing capacity of the rigid-flexible composite pile for the upper load; while the vertical axis represents the soil depth, which increases from the origin of the rectangular coordinate system.

[0015] In this embodiment, the curves of the axial force of the rigid-flexible composite pile along the depth direction, the curves of the lateral resistance and end resistance along the depth direction, and the curves of the bearing capacity of the pile along the depth direction are automatically constructed by inputting pile foundation design parameters and soil layer parameters.

[0016] The pile foundation design parameters include the total pile length, pile outer diameter, core pile concrete grade, core pile steel grade, pile top vertical design load, number of pile head blades, pile head blade width, pile diameter ratio of rigid piles to flexible piles, strength of rigid piles, and bonding force between rigid and flexible piles. Among these, the total pile length, pile outer diameter, core pile concrete grade, core pile steel grade, and pile top vertical design load are relatively common parameters. The number of pile head blades and the width of the pile head blades refer to the fact that, in this embodiment, when the flexible pile is a cement-soil mixing pile, the mixing head with mixing blades is retained in the soil layer. This increases the connection performance between the steel pipe core pile and the cement-soil mixing body, improving the bearing capacity of the pile foundation. Furthermore, the mixing blades act as an enlargement of the pile head of the steel pipe core pile, further enhancing the bearing capacity of the steel pipe core pile.

[0017] The soil parameters are divided into several soil layers according to depth, which are obtained from the geotechnical exploration work before pile foundation construction. The soil layer parameters include the soil layer thickness, pile-soil lateral resistance, end resistance, lateral resistance coefficient, end resistance coefficient, and end resistance folding coefficient for each soil layer.

[0018] 2) such as Figure 3 As shown, when the curves of the axial force along the depth direction of the pile are enveloped by the curves of the side resistance and end resistance along the depth direction, as well as the curve of the bearing capacity along the depth direction, the pile foundation parameters of the rigid-flexible composite pile are adjusted. In this case, the three curves are driven to change by the adjusted pile foundation parameters; that is, each curve changes its state in the rectangular coordinate system as the pile foundation parameters are adjusted. Under the premise of curve envelopment, the three curves are brought closer together to improve their matching and overlap, thus obtaining the adjusted pile foundation design parameters.

[0019] 3) Based on the axial force curve of the pile, segment the axial force distribution of the pile along the depth direction of the rigid-flexible composite pile. For example... Figure 2 As shown, in this embodiment, the cross-section of the rigid pile is gradually reduced along the depth direction to match the strength bearing capacity of the pile body with the axial force of the pile body.

[0020] When steel pipe core piles are used as rigid piles, the pile foundation design parameters also include the segment length of each segment, the outer diameter of the steel pipe in each segment, the wall thickness of the steel pipe, and the characteristic value of the side resistance of the outer wall of the steel pipe.

[0021] Although the above embodiments have described the concept and embodiments of the present invention in detail with reference to the accompanying drawings, those skilled in the art will recognize that various improvements and modifications can still be made to the present invention without departing from the scope of the claims, and therefore will not be elaborated here.

Claims

1. A segmented design calculation method based on the axial force distribution of a rigid-flexible composite pile, wherein the rigid-flexible composite pile is composed of rigid piles and flexible piles, the rigid piles being arranged among the flexible piles, wherein the rigid piles bear the superstructure load, and the flexible piles obtain frictional force from the surrounding soil, characterized in that: The segmented design calculation method includes: establishing the variation curves of the axial force of the pile body along the depth direction, the variation curves of the side resistance and end resistance along the depth direction, and the variation curve of the pile bearing capacity along the depth direction of the rigid-flexible composite pile; when the variation curve of the axial force of the pile body along the depth direction is enveloped by the variation curves of the side resistance and end resistance along the depth direction and the variation curve of the pile bearing capacity along the depth direction, adjusting the pile foundation parameters of the rigid-flexible composite pile to make the three curves closer and improve the matching and overlap of the three curves, thereby obtaining the adjusted pile foundation design parameters.

2. The segmented design calculation method based on the axial force distribution of a rigid-flexible composite pile according to claim 1, characterized in that: Based on the axial force curve of the pile body, the axial force distribution of the pile body is segmented along the depth direction of the rigid-flexible composite pile.

3. According to claim 2, the segmented design calculation method based on the axial force distribution of a rigid-flexible composite pile involves: gradually reducing the cross-section of the rigid pile along the depth direction to match the pile's strength bearing capacity with the pile's axial force.

4. The segmented design calculation method based on the axial force distribution of a rigid-flexible composite pile according to claim 1, characterized in that: The pile foundation parameters include at least the pile diameter ratio of the rigid pile and the flexible pile, the strength of the rigid pile, and the bonding force between the rigid pile and the flexible pile.

5. The segmented design calculation method based on the axial force distribution of a rigid-flexible composite pile according to claim 1, characterized in that: The curves of the axial force along the depth direction, the side resistance and end resistance along the depth direction, and the bearing capacity along the depth direction of the rigid-flexible composite pile are automatically constructed by inputting pile foundation design parameters and soil layer parameters.

6. The segmented design calculation method based on the axial force distribution of a rigid-flexible composite pile according to claim 5, characterized in that: The soil parameters are divided into several soil layers according to the depth direction, including the soil layer thickness of each soil layer, the side resistance between the pile and the soil, the end resistance, the side resistance coefficient, the end resistance coefficient, and the end resistance folding coefficient.

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