CN-121994692-A - Method for judging damage state of soil body around offshore wind power pile foundation

CN121994692ACN 121994692 ACN121994692 ACN 121994692ACN-121994692-A

Abstract

The invention discloses a method for judging the damage state of soil around an offshore wind power pile foundation, which comprises the steps of S1, carrying out a soil indoor cyclic load test, obtaining a cyclic shear strain accumulation diagram, S2, obtaining complex wave force load data, converting the complex wave force load data into a group of cyclic shear stress ratio data with small-to-large order, finding out the minimum cyclic shear stress ratio and the corresponding cyclic vibration times, obtaining the equivalent cyclic vibration times corresponding to the next cyclic shear stress ratio based on the cyclic shear strain accumulation diagram obtained in S1, repeating the same operation until obtaining the final equivalent cyclic vibration times corresponding to the maximum cyclic shear stress ratio, S3, obtaining the corresponding damage vibration times under different working conditions, obtaining a damage vibration times equivalent diagram, S4, finding out the corresponding damage vibration times in the damage vibration times equivalent diagram obtained in S3 according to the average shear stress, comparing the final equivalent cyclic vibration times with the damage vibration times, and judging whether the soil is damaged or not. The method reduces the cost, has high universality and can ensure the precision.

Inventors

YANG JIANQUAN
LIU LIANGZHI
LIU RUN
LI CHENGFENG

Assignees

天津大学

Dates

Publication Date: 20260508
Application Date: 20260202

Claims (8)

1. A method for judging the damage state of soil around an offshore wind power pile foundation is characterized by comprising the following steps: s1, carrying out an indoor cyclic load test of a soil body, and obtaining a cyclic shear strain accumulation chart: Collecting undisturbed soil around a offshore wind power pile foundation, expanding an indoor soil cyclic load test of a system, and drawing an contour line distribution diagram of different cyclic shear strains by taking a cyclic shear stress ratio as a vertical axis and cyclic vibration times as a horizontal axis; In the contour map, when the cycle vibration frequency is 1, the cycle shear strain is obtained Drawing the corresponding relation between the cyclic shear stress ratio and the cyclic shear strain at the moment A graph of the change relation with the cyclic shear stress ratio; the two images are corresponding to each other according to the cyclic shear stress ratio to form a complete cyclic shear strain accumulation image; S2, acquiring complex wave force load data of an undisturbed soil body in a period of time, converting the complex wave force load data into a group of cyclic shear stress ratio data with a small-to-large order, finding out the minimum cyclic shear stress ratio and the corresponding cyclic vibration times, obtaining the equivalent cyclic vibration times corresponding to the next cyclic shear stress ratio based on the cyclic shear stress accumulation diagram obtained in the S1, and repeating the same operation until obtaining the final equivalent cyclic vibration times corresponding to the maximum cyclic shear stress ratio ; S3, carrying out an indoor circulation triaxial test on an undisturbed soil body around the offshore wind power pile foundation to obtain corresponding damage vibration times under different working conditions Obtaining the breaking vibration times with the horizontal axis as the average shear stress ratio and the vertical axis as the cyclic shear stress ratio A contour map; S4, according to the average shear stress of the undisturbed soil body of the target area obtained by measurement In the damage vibration order contour map obtained in the step S3, the corresponding damage vibration order is found The final equivalent cycle vibration frequency obtained in S2 Vibration frequency of destruction And comparing to judge whether the soil body is damaged.
2. The method for judging the damage state of the soil around the offshore wind pile foundation according to claim 1, wherein in step S1: The cyclic shear stress ratio And cycle vibration times Cyclic shear strain of (2) The contour map can represent the ratio of cyclic shear stress when the cyclic shear strain generated by the soil body is the same And cycle vibration times Is a variation of (1); wherein the cyclic shear stress ratio The ratio of the cyclic shear stress of the undisturbed soil body to the twice of the non-drainage shear strength is normalized, Is the cyclic shear stress of the undisturbed soil body, The shear strength is not drained for undisturbed soil.
3. The method for judging the damage state of soil around the offshore wind pile foundation according to claim 2, wherein in the step S2, the complex wave force load data comprises load size and number of load occurrence, and the wave force load is used as cyclic shear stress According to the ratio of cyclic shear stress The wave force load is converted into the cyclic shear stress ratio to obtain a group of cyclic shear stress ratio data which are ordered from small to large.
4. The method for judging the damage state of the soil body around the offshore wind power pile foundation according to claim 3, wherein the method for obtaining the equivalent cyclic vibration times in the step S2 is as follows: According to the obtained cyclic shear stress ratio data of a group of sequences from small to large, finding out the cyclic vibration times corresponding to the minimum cyclic shear stress ratio, finding out a corresponding point B in the cyclic shear strain accumulation diagram obtained in the step S1, and according to the cyclic shear strain where the point B is located The contour line obtains the corresponding cyclic shear strain A value; Finding the next cyclic shear stress ratio data, and applying the cyclic shear stress Under the condition of unchanged state, at the current cycle, shearing strain Moving on the contour line to find a data point C corresponding to the cyclic shear stress ratio data; At the moment of increasing the cyclic shear stress ratio, the cyclic shear strain of the soil body changes to generate increment ; The ratio of the cyclic shear stress is unchanged, the data point C is transversely moved, and the current cyclic shear strain adding increment is found Cyclic shear strain corresponding to the post value Data point D on the contour line, wherein the value of the cyclic vibration frequency corresponding to the data point D is the current equivalent cyclic vibration frequency Data point D is the initial state of the continued cycle at the next cycle shear stress ratio.
5. The method for judging the damage state of soil around the offshore wind pile foundation according to claim 1, wherein the specific operation in the step S3 is as follows: Carrying out a large number of indoor soil cyclic load tests on undisturbed soil around pile foundations in a target area to circularly shear strain Reaching 15 percent as a judgment limit of soil body damage, and obtaining corresponding damage vibration times under different working conditions Then obtaining the destroyed vibration times through fitting Contour map, same destructive vibration times The contour is divided into three phases.
6. The method for determining a failure state of a soil body surrounding a foundation of an offshore wind farm pile as set forth in claim 5, wherein the different conditions in step S3 are different average shear stresses And cyclic shear stress 。
7. The method for judging the damage state of the soil around the offshore wind pile foundation according to claim 6, wherein in step S3: the first and second stage fitting formulas are: (1) and a third stage fitting formula: (2)。
8. The method for judging the damage state of soil around the offshore wind pile foundation according to claim 7, wherein the specific operation in the step S2 is as follows: according to the average shear stress of the undisturbed soil body obtained by measurement Ratio to the maximum cyclic shear stress of S2, the failure vibration frequency obtained in S3 In the contour map, find the corresponding failure vibration times And S22, final equivalent cycle vibration times are obtained Vibration frequency of destruction Comparing, and judging the damage state and the damage degree of the soil body: When (when) ≥ When the soil body is damaged, judging that the soil body is damaged; When (when) < And when the soil body is not damaged, judging.

Description

Method for judging damage state of soil body around offshore wind power pile foundation Technical Field The invention relates to the technical field of ocean wind power engineering, in particular to a method for judging the damage state of soil around an offshore wind power pile foundation. Background Offshore wind power is gradually pushed to deep open sea and high power directions as a key path for adjusting energy structures in China. In the development process, the fan foundation structure bears the continuous action of complex cyclic loads such as wind, waves, currents and the like for a long time, and the soil body of the offshore site is mostly soft clay, so that the response to the cyclic loads is particularly sensitive. The interaction of the wind turbine pile foundation and surrounding soil bodies directly determines the stability, bearing capacity and long-term operation safety of the foundation structure, and under the action of long-term cyclic load, the soil bodies are extremely easy to have the problems of accumulated plastic deformation, rigidity degradation, strength attenuation and the like, so that the weakening of pile-soil interfaces, excessive foundation settlement and even overall instability are caused, and the safety and service life of the offshore wind power pile structure are seriously influenced. At present, the main modes for evaluating the damage and deformation conditions of soil around a wind power pile foundation under a cyclic load are as follows: Firstly, through directly carrying out a cyclic load test of interaction between a structure and a soil body on site, although the method is visual, a large number of repeated tests are needed, the test cost is extremely high, the period is long, the test result is affected by the difference of the soil body properties, the universality of the test result is poor, and the method cannot be suitable for engineering designs of different sites; Secondly, by means of a method for carrying out numerical simulation of soil mass and combining a complex cyclic constitutive model, finite element or finite difference numerical simulation prediction is carried out. Therefore, development of a method which is driven based on test data, has strong engineering applicability and can quantitatively judge the soil body damage state under the cyclic load becomes an urgent need in the field of offshore wind power pile foundation design and safety evaluation. Disclosure of Invention Aiming at the defects existing in the prior art, the invention provides a method for judging the damage state of soil around an offshore wind power pile foundation. For this purpose, the invention adopts the following technical scheme: a method for judging the damage state of soil around an offshore wind power pile foundation is characterized by comprising the following steps: s1, carrying out an indoor cyclic load test of a soil body, and obtaining a cyclic shear strain accumulation chart: Collecting undisturbed soil around a offshore wind power pile foundation, expanding an indoor soil cyclic load test of a system, and drawing an contour line distribution diagram of different cyclic shear strains by taking a cyclic shear stress ratio as a vertical axis and cyclic vibration times as a horizontal axis; In the contour map, when the cycle vibration frequency is 1, the cycle shear strain is obtained Drawing the corresponding relation between the cyclic shear stress ratio and the cyclic shear strain at the momentA graph of the change relation with the cyclic shear stress ratio; the two images are corresponding to each other according to the cyclic shear stress ratio to form a complete cyclic shear strain accumulation image; S2, acquiring complex wave force load data of an undisturbed soil body in a period of time, converting the complex wave force load data into a group of cyclic shear stress ratio data with a small-to-large order, finding out the minimum cyclic shear stress ratio and the corresponding cyclic vibration times, obtaining the equivalent cyclic vibration times corresponding to the next cyclic shear stress ratio based on the cyclic shear stress accumulation diagram obtained in the S1, and repeating the same operation until obtaining the final equivalent cyclic vibration times corresponding to the maximum cyclic shear stress ratio ; S3, carrying out an indoor circulation triaxial test on an undisturbed soil body around the offshore wind power pile foundation to obtain corresponding damage vibration times under different working conditionsObtaining the breaking vibration times with the horizontal axis as the average shear stress ratio and the vertical axis as the cyclic shear stress ratioA contour map; S4, according to the average shear stress of the undisturbed soil body of the target area obtained by measurement In the damage vibration order contour map obtained in the step S3, the corresponding damage vibration order is foundThe final equivalent cycle vibration f