Single-pile vertical settlement design method based on energy dissipation

Abstract

The invention discloses a single-pile vertical settlement design method based on energy dissipation. The single-pile vertical settlement design method comprises the steps that S1, pile top settlement of a pile body is assumed to be a minimum value S0 larger than zero; s2, sequentially calculating the end axial force and the end settlement of each unit from the first unit until the end axial force Pn and the end settlement Sn of the nth unit are obtained; s3, the Pn calculated in the step S2 is utilized, and pile end settlement of the pile body is calculated through pile end soil body analysis; and S4, checking whether the Sb calculated in the step S2 is equal to the Sb calculated in the step S3 or not. The method has the advantages that the settlement process of the single pile is analyzed from the angle of energy dissipation, an equivalent displacement coordination equation is established through energy conversion analysis of a pile body, a soil body and a pile-soil system, the single pile vertical settlement design method based on energy dissipation is established on the basis, and the method is based on the uniqueness of a solution and has the advantages that the design accuracy is improved. And a reasonable solution is searched in a searching mode.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pile foundation, in particular to a single pile vertical settlement design method based on energy dissipation. BACKGROUND

[0002] Pile foundation is composed of piles set in rock-soil and bearing platform connected with pile top. Pile foundation is a widely used form of foundation in engineering construction. In recent years, with the construction of high-rise buildings and cross-river and cross-sea bridges, the settlement requirements of pile foundation for upper structure are increasingly strict.

[0003] The settlement of pile foundation is based on experience or empirical formula. The main methods for calculating single pile settlement at present are as follows: load transfer method, elastic theory method and shear displacement method. The traditional design method is mainly a simplified theoretical method based on empirical formula, which is not rigorous enough in theory. SUMMARY

[0004] The present application aims to provide a single pile vertical settlement design method based on energy dissipation, which analyzes the single pile settlement process from the perspective of energy dissipation, establishes an equivalent displacement coordination equation through energy conversion analysis of pile body, soil body and pile-soil system, and establishes a single pile vertical settlement design method based on energy dissipation. This method is based on the uniqueness of the solution and finds reasonable answers through searching.

[0005] The present application is achieved by the following technical solutions:

[0006] A single pile vertical settlement design method based on energy dissipation, the method comprising the following steps:

[0007] S1: assuming that the pile top settlement of the pile body is a minimum value S0 greater than zero;

[0008] wherein the pile body is uniformly divided into n units from top to bottom, and the corresponding soil around the pile is divided into n layers, forming n+1 interfaces; each of the interfaces is 0, 1, 2…, n-1, n, and the depths of each of the interfaces are Z0, Z1, Z2…, Z n-1 , Z n , the shaft force and displacement of the pile body at the i interface are P i and S i , respectively;

[0009] S2: from the first unit, the end shaft force and end settlement of each unit are calculated in turn until the end shaft force P n and end settlement S n of the n-th unit are obtained;

[0010] wherein P n =P b, S n = S b ; P b is the pile tip axial force of the pile body, S b is the pile tip settlement of the pile body.

[0011] S3: using P n calculated in step S2, the pile tip settlement S' b of the pile body is analyzed and calculated through the pile tip soil body.

[0012] S4: checking whether S b calculated in step S2 is equal to S' b calculated in step S3; if S b and S' b are equal, the assumed S0 is the accurate solution; if S b and S' b are not equal, S0 is re-assumed, steps S2 to S3 are repeated until S b = S' b , and the re-assumed S0 is the accurate solution.

[0013] In step S2,

[0014] the pile side friction τ1 of the first unit is obtained according to the τ~S relationship of the soil body around the pile;

[0015] through unit calculation, the unit compression amount ΔS1, the end axial force P1 and the end settlement S1 of the first unit are obtained according to the top axial force P0, the top settlement S0 and the pile side friction τ1 of the first unit:

[0016]

[0017] P1 = P0 - τ1 * ΔL * U0;

[0018] S1 = S0 - ΔS1;

[0019] In the formula, the elastic modulus of the pile body is E, the cross-sectional area is A, the pile cross-sectional circumference is U0, and the unit length is ΔL.

[0020] In step S2,

[0021] the unit compression amount ΔS2, the end axial force P2 and the end settlement S2 of the second unit are calculated according to the calculated P1 and S1, and the ΔS i , P i , S i can be obtained by recursive calculation, where i = 3~n.

[0022] In step S3,

[0023] S' bThe local experience can be determined, and when there is no reference experience, the following formula can be used to calculate:

[0024]

[0025] In the formula, d is the diameter of the pile end, E S is the elastic modulus of the soil at the pile end, μ s is the Poisson's ratio of the soil.

[0026] In step S4,

[0027] The pile top settlement S0 is re-assumed as the last round S0 plus a small increment Δ s .

[0028] The advantages of the present application are: from the perspective of energy dissipation, the single pile settlement process is analyzed, the equivalent displacement coordination equation is established through the energy conversion analysis of the pile, the soil and the pile-soil system, and on this basis, the single pile vertical settlement design method based on energy dissipation is established. The method is based on the uniqueness of the solution, and reasonable answers are found through searching. BRIEF DESCRIPTION OF DRAWINGS

[0029] Fig. 1 The flowchart of the single pile vertical settlement design method based on energy dissipation of the present application;

[0030] Fig. 2 The settlement analysis diagram of the single pile of the present application. DETAILED DESCRIPTION

[0031] The features and other related features of the present application are further described in detail below with reference to the accompanying drawings, so as to facilitate the understanding of the same by the skilled in the art:

[0032] Embodiment: as Figs. 1-2 shown, the present embodiment relates to a single pile vertical settlement design method based on energy dissipation, which method specifically comprises the following steps:

[0033] S1: assume that the pile top settlement of the pile body is a very small value S0 greater than zero.

[0034] Wherein, the pile body is uniformly divided into n units from top to bottom, and the corresponding soil around the pile is divided into n layers, forming n+1 interfaces; each interface is 0, 1, 2…, n-1, n, the pile shaft force and the pile displacement of the i-th interface are P i and S i . It should be noted that the pile shaft force and the pile displacement of the i-th (i is 1-n) interface are the end shaft force and the end settlement of the i-th unit, and the pile shaft force and the pile displacement of the 0-th interface are the pile top shaft force (the top shaft force of the 1st unit) and the pile top settlement (the top settlement of the 1st unit).

[0035] S2: Starting from the first unit, calculate the end axial force and end settlement of each unit sequentially until the end axial force P of the nth unit is obtained. n and end settlement S n .

[0036] Among them, P n =P b S n =S b ;P b S is the axial force at the pile tip. b This refers to the settlement at the pile tip.

[0037] Specifically, the pile side friction τ1 of the first unit is obtained based on the τ~S relationship of the soil around the pile.

[0038] Through element calculations, based on the top axial force P0, top settlement S0, and pile side friction τ1 of element 1, the element compression ΔS1, end axial force P1, and end settlement S1 of element 1 are calculated:

[0039]

[0040] P1 = P0 - τ1 * ΔL * U0;

[0041] S1 = S0 - ΔS1;

[0042] In the formula, the elastic modulus of the pile is E, the cross-sectional area is A, the perimeter of the pile section is U0, and the element length is ΔL.

[0043] Based on the calculated P1 and S1, the unit compression ΔS2, end axial force P2, and end settlement S2 of the second unit can be calculated. ΔS can be obtained by recursion. i P i S i , where i = 3 to n.

[0044] S3: P calculated using step S2 n The pile tip settlement S' is calculated through pile tip soil analysis. b .

[0045] Among them, S' b It can be determined based on local experience. When there is no reference experience, it can be calculated using the following formula:

[0046]

[0047] In the formula, d is the pile tip diameter, and E S Let μ be the elastic modulus of the soil at the pile tip. s The Poisson's ratio of the soil.

[0048] S4: Verify the S calculated in step S2 bIs it equal to S' calculated in step S3? b If S b and S' b If they are equal, assume S0 is the exact solution; if S b and S' b If they are not equal, re-assume S0 and repeat steps S2 to S3 until S0 is equal to S0. b =S' b The re-assumed S0 is the exact solution.

[0049] In this context, it is re-assumed that the pile top settlement S0 is the previous S0 plus a small increment Δ. s .

[0050] The beneficial technical effects of this embodiment are as follows: the settlement process of a single pile is analyzed from the perspective of energy dissipation. An equivalent displacement coordination equation is established by analyzing the energy conversion of the pile, soil and pile-soil system. On this basis, a single pile vertical settlement design method based on energy dissipation is established. This method is based on the uniqueness of the solution and finds a reasonable solution by searching.

[0051] 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 method for designing the vertical settlement of a single pile based on energy dissipation, characterized in that... The method includes the following steps: S1: Assume that the settlement at the top of the pile is a minimum value S0 that is greater than zero; The pile body is uniformly divided into n units from top to bottom, and the corresponding surrounding soil is divided into n layers, forming n+1 interfaces; each interface is 0, 1, 2..., n-1, n, and the depth of each interface is Z0, Z1, Z2..., Z... n-1 Z n The axial force and displacement of the pile at the i-th interface are respectively P i and S i ; S2: Starting from the first unit, calculate the end axial force and end settlement of each unit sequentially until the end axial force P of the nth unit is obtained. n and end settlement S n ; Among them, P n =P b S n =S b ;P b S is the axial force at the pile tip. b For the settlement of the pile tip; S3: P calculated using step S2 n The pile tip settlement S' is calculated through pile tip soil analysis. b ; S4: Verify the S calculated in step S2 b Is it equal to S' calculated in step S3? b If S b and S' b If they are equal, assume S0 is the exact solution; if S b and S' b If they are not equal, re-assume S0 and repeat steps S2 to S3 until S0 is equal to S0. b =S' b The re-assumed S0 is the exact solution.

2. The method for designing vertical settlement of a single pile based on energy dissipation as described in claim 1, characterized in that... In step S2, The pile side friction τ1 of the first unit is obtained based on the τ~S relationship of the soil around the pile. Through element calculations, based on the top axial force P0, top settlement S0, and pile side friction τ1 of element 1, the element compression ΔS1, end axial force P1, and end settlement S1 of element 1 are calculated: P1 = P0 - τ1 * ΔL * U0; S1 = S0 - ΔS1; In the formula, the elastic modulus of the pile is E, the cross-sectional area is A, the perimeter of the pile section is U0, and the element length is ΔL.

3. The method for designing vertical settlement of a single pile based on energy dissipation as described in claim 2, characterized in that... In step S2, Based on the calculated P1 and S1, the unit compression ΔS2, end axial force P2, and end settlement S2 of the second unit can be calculated. ΔS can be obtained by recursion. i P i S i , where i = 3 to n.

4. The method for designing vertical settlement of a single pile based on energy dissipation as described in claim 3, characterized in that... In step S3, S' b It can be determined based on local experience. When there is no reference experience, it can be calculated using the following formula: In the formula, d is the pile tip diameter, and E S Let μ be the elastic modulus of the soil at the pile tip. s The Poisson's ratio of the soil.

5. The method for designing vertical settlement of a single pile based on energy dissipation as described in claim 4, characterized in that... In step S4, Let's re-assume that the pile top settlement S0 is the previous S0 plus a small increment Δ. s .

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