WO2024060608A1 - 海上风电桩基土塞挤土效应的评估模型设计及评估方法 - Google Patents

海上风电桩基土塞挤土效应的评估模型设计及评估方法 Download PDF

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WO2024060608A1
WO2024060608A1 PCT/CN2023/089878 CN2023089878W WO2024060608A1 WO 2024060608 A1 WO2024060608 A1 WO 2024060608A1 CN 2023089878 W CN2023089878 W CN 2023089878W WO 2024060608 A1 WO2024060608 A1 WO 2024060608A1
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measurement
pile
cptu
model
soil
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PCT/CN2023/089878
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English (en)
French (fr)
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沈盼盼
周洁
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上海勘测设计研究院有限公司
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Publication of WO2024060608A1 publication Critical patent/WO2024060608A1/zh

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    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D33/00—Testing foundations or foundation structures

Definitions

  • the invention relates to the field of geotechnical engineering, and specifically relates to an evaluation model design and evaluation method for the soil congestion effect of offshore wind power pile foundations.
  • the cone penetration test (CPTU) is an important in-situ testing technology in the field of geotechnical engineering. It is currently mainly used for soil layer division, site liquefaction identification, estimation of physical and mechanical parameters of foundation soil layers, assessment of foundation bearing capacity, and estimation of pile foundation bearing capacity.
  • the piezocone penetration test (CPTU) is currently an important reference for the design parameters of offshore wind power pile foundation projects. It has the advantages of being intuitive, fast, and having data continuity. Indicators such as the penetration resistance of the test soil layer can be directly obtained on site, which directly reflects the physical and mechanical properties of the soil around the pile.
  • the technical problem to be solved by the present invention is to provide an evaluation model design and evaluation method for the soil congestion effect of offshore wind power pile foundations, adopting a model test method, which can conveniently, accurately and systematically To evaluate the soil plugging effect of pile foundations, the influencing factors are controllable and the cost is low.
  • the present invention provides an evaluation model design method for the soil congestion effect of offshore wind power pile foundations, which includes the following steps:
  • the CPTU measurement system including the CPTU penetration mechanism, CPTU probe and CPTU data collector.
  • the CPTU probe is set at the measurement point on the measurement positioning line.
  • the CPTU probe is connected to the CPTU data collector.
  • the CPTU penetration mechanism is used for Penetrate the CPTU probe into the test soil; connect the CPTU data collector to the computer;
  • the model pile is set at the pile installation position.
  • the loading system is connected to the model pile and is used to apply load to the model pile.
  • the axial force detection system is used to detect the axial force of the model pile.
  • the axial force detection system is connected to the computer.
  • step S2 the pile installation position is located at the center of the model box.
  • the number of measurement positioning lines is an even number, and the measurement positioning lines are evenly distributed around the pile installation positions.
  • Each measurement positioning line is used for the measurement of the model pile under a certain level of load.
  • the distance L between the measurement points is greater than 10d, where d is the diameter of the CPTU probe used to measure at the measurement points.
  • step S3 the test soil is prepared according to the geotechnical test method standard GB/T 50123-2019, and the filling soil is evenly dense and fully saturated.
  • the CPTU measurement system also includes a positioning rail.
  • the positioning rail is installed above the measurement positioning line.
  • the CPTU probe is installed on the positioning rail and can move to the measurement point on the positioning rail.
  • the axial force detection system includes an optical fiber sensor and an optical fiber data collector.
  • the optical fiber sensor is installed in the model pile.
  • the optical fiber sensor is connected to the optical fiber data collector, and the optical fiber data collector is connected to the computer.
  • the invention also provides a method for evaluating the soil congestion effect of offshore wind power pile foundations, which includes the following contents:
  • the CPTU benchmark value of the test soil is obtained through the CPTU measurement system
  • the specified load is applied to the model pile through the loading system.
  • the model pile is drilled into the test soil, and the axial force of the model pile is obtained through the axial force detection system.
  • a certain measurement positioning line under the load is obtained through the CPTU measurement system.
  • Both evaluation models perform the following operations: According to the test requirements, the specified load is applied to the model pile through the loading system, the model pile is drilled into the test soil, and the axial force of the model pile is obtained through the axial force detection system, and the CPTU measurement system is used. Obtain the CPTU measurement value of the test soil at the measurement point on a certain measurement positioning line under the load;
  • the loading system applies load to the model pile by graded static loading or cyclic dynamic loading, and the load directions include horizontal and vertical directions.
  • the loading system performs graded static loading on the model pile, and each grade of load is measured at the measurement point of a measurement positioning line by the CPTU measurement system.
  • evaluation model design method and evaluation method involved in the present invention have the following beneficial effects:
  • CPTU data has high accuracy and large quantity, which can directly reflect the properties of foundation soil and facilitate the assessment of soil congestion effects.
  • the types of variables that can be set in the model include pile type, load direction, type, duration, etc., which facilitates the study of the impact of different factors on the properties of pile foundations.
  • Figure 1 is a schematic diagram of the evaluation model designed by the present invention.
  • Figure 2 is a schematic diagram of the position of the measurement positioning line and measurement points in the present invention.
  • model box 2 Test soil 3 model piles 4 Load the system 5 fiber optic sensors 6 positioning track 7 CPTU penetration mechanism 8 CPTU probe 9 Fiber optic data collector 10 CPTU data collector 11 computers 12 trusses 13 pile installation positions 14 First measurement positioning circle 15 Second measurement positioning circle 16 Third measurement positioning circle 17 Measurement positioning line 18 measuring points
  • the present invention provides an evaluation model design method for the soil congestion effect of offshore wind power pile foundations.
  • the evaluation model includes a model box 1, a test soil 2, a model pile 3, a loading system 4, and a CPTU measurement system. , axial force detection system and other structures.
  • the evaluation model design method includes the following steps:
  • the pile installation position 13 is a circular area, and the first measurement positioning circle 14 and the second measurement positioning are set with the center of the pile installation position 13 as the center of the circle.
  • Circle 15 and the third measurement positioning circle 16, and the diameters of the first measurement positioning circle 14, the second measurement positioning circle 15 and the third measurement positioning circle 16 are 1D ⁇ 2D, 5D ⁇ 6D respectively. and 6D ⁇ 10D, D is the diameter of model pile 3.
  • the pile installation position 13 is preferably located at the center of the model box 1 .
  • the first measurement positioning circle 14 , the second measurement positioning circle 15 and the third measurement positioning circle 16 respectively represent the three position areas near the pile body, the edge of the plastic zone and outside the plastic zone of the model pile 3 .
  • a straight line is set radially along the pile installation position 13 as the measurement positioning line 17.
  • the intersection of the measurement positioning line 17 and the first measurement positioning circle 14, the second measurement positioning circle 15 and the third measurement positioning circle 16 is used as the measurement point 18.
  • the measurement point Position 18 is used for the measurement positioning of the CPTU probe 8 of the CPTU measurement system.
  • the number of measurement positioning lines 17 is set according to the loading conditions of the model pile 3 (including load classification, load cycle time and other factors).
  • the number of measurement positioning lines 17 is preferably an even number. See Figure 2.
  • the measurement positioning lines 17 There are four, and the four measurement positioning lines 17 are evenly distributed around the pile installation position 13, that is, the measurement positioning lines 17 are spaced 90° apart, and each pair is symmetrical.
  • the four measurement positioning lines 17 are used for the model pile 3 at the P1 to P4 level respectively.
  • the four measurement positioning lines 17 are numbered P1 to P4 respectively.
  • the measurement points 18 on it are numbered Pn-1 and Pn-2 from the inside to the outside. and Pn-3.
  • the distance L between the measurement points 18 is greater than 10d. Specifically, the distance L between the measurement points 18 on the same measurement positioning line 17 and the distance L between the measurement points 18 on different measurement positioning lines 17 are both Greater than 10d, where d is the diameter of the CPTU probe 8 to ensure that when the CPTU probe 8 of the CPTU measurement system is used for subsequent measurements, the CPTU probes 8 will not affect each other.
  • test soil 2 according to the specified requirements; specifically, in this embodiment, take the seabed soil from the sea area where the offshore wind power pile foundation is located, and prepare the test according to the geotechnical test method standard GB/T 50123-2019 Use soil 2. Fill the soil evenly, densely and fully.
  • the CPTU probe 8 is set at the measurement point 18 on the measurement positioning line 17.
  • the CPTU probe 8 and the CPTU data collector 10 connection the measured data can be transmitted to the CPTU data collector 10, the CPTU penetration mechanism 7 is used to penetrate the CPTU probe 8 into the test soil 2; the CPTU data collector 10 is connected to the computer 11, and the data can be transmitted Go to computer 11 for storage, analysis and calculation.
  • the size of each part of the CPTU measurement system is selected according to the size of the simulation box. Since the evaluation model is usually completed indoors, a miniature CPTU measurement system is selected.
  • the CPTU measurement system also includes a positioning rail 6.
  • the positioning rail 6 is installed above the measurement positioning line 17.
  • the CPTU probe 8 is installed on the positioning rail 6 and can move to the measurement point on the positioning rail 6.
  • Position 18, the positioning track 6 specifically includes four horizontal tracks and a switching track. The four horizontal tracks are respectively set directly above the four measurement positioning lines 17 and are parallel to the measurement positioning lines 17.
  • the CPTU probe 8 can move on the horizontal tracks.
  • switch tracks connect each horizontal track for the CPTU probe 8 to move from one horizontal track to another.
  • the movement of the CPTU probe 8 on the positioning track 6 is controlled by the computer 11.
  • the computer class controls The CPTU probe 8 is moved to the corresponding measurement positioning line 17.
  • the model pile 3 is set at the pile installation position 13.
  • the loading system 4 is connected to the model pile 3 to apply load to the model pile 3.
  • the applied load includes Lateral and vertical loads.
  • the loading system 4 is capable of drilling the model pile 3 into the test soil 2 and applying various loads to the model pile 3 drilled into the test soil 2 .
  • the axial force detection system is used to detect the axial force of the model pile 3.
  • the axial force detection system is connected to the computer 11 and can transmit the detection data to the computer 11 for storage, calculation and analysis.
  • the loading system 4 is installed on the truss 12 above the model box 1 and is firmly connected to the model pile 3. It has a power system that meets the test requirements.
  • the computer 11 controls the start and stop of loading, as well as the size and load of the load. Way.
  • the axial force detection system includes an optical fiber sensor 5 and an optical fiber data collector 9.
  • the optical fiber sensor 5 is installed in the model pile 3 and continuously monitors the axial force of the model pile 3 during the test; the optical fiber sensor 5 is connected to the optical fiber data collector 9 , the optical fiber data acquisition instrument 9 is connected to the computer 11.
  • the axial force detection system can also have other suitable structures, as long as it can realize the above-mentioned real-time monitoring of the axial force of the model pile 3 .
  • the evaluation model design method of the present invention can be used to evaluate the soil plugging effect of pile foundations. It adopts a model test method and is based on pore pressure static cone testing (CPTU) technology to conveniently, accurately and systematically evaluate the soil of pile foundations. Compared with the soil congestion effect on site, the influencing factors are controllable and the cost is low.
  • CPTU pore pressure static cone testing
  • the present invention also provides a method for evaluating the soil plugging effect of offshore wind power pile foundations, which includes two parts: pile foundation soil plugging effect evaluation and pile foundation soil plugging effect evaluation, specifically as follows:
  • A1 Use the evaluation model design method described above to set up the evaluation model.
  • there are multiple measurement positioning lines 17 in the evaluation model and the number is an even number, and the measurement positioning lines 17 are evenly distributed around the pile installation positions 13 .
  • model pile 3 Before the model pile 3 is drilled into the test soil 2, it is measured through the CPTU measurement system to obtain various physical parameters of the test soil 2, including cone tip resistance, side wall friction resistance, pore water pressure and other parameters, as the test soil. CPTU benchmark value of 2.
  • the specified load is applied to the model pile 3 through the loading system 4.
  • the model pile 3 is drilled into the test soil 2, and the axial force of the model pile 3 is obtained through the axial force detection system, and the load under the load is obtained through the CPTU measurement system.
  • Various physical parameters of the test soil 2 at the measurement point 18 on a certain measurement positioning line 17 are transmitted to the computer 11 as the CPTU measurement value of the test soil 2, the axial force data and the CPTU measurement value of the CPTU measurement system.
  • the pile pressure load of the model test is designed according to similar theories.
  • the loading system 4 applies load to the model pile 3 in either graded static loading or cyclic dynamic loading. Loading to study the influence of different loads on the soil squeezing effect of offshore wind power pile foundations.
  • each level of load is beneficial
  • the pile pressing load is divided into 4 levels, recorded as load P1.
  • the CPTU probe 8 tests the P 1-1 , P 1-2 , and P 1-3 points, and records the cone tip resistance, side wall friction resistance, pore water pressure and other parameters.
  • the axial force of the model pile 3 is monitored through the optical fiber sensor 5.
  • load P2 to P4 loads in the same manner, and measure at three measuring points 18 corresponding to the P2 to P4 measurement positioning lines 17 to complete the pile pressing test.
  • the computer controls the loading system 4 to change the load, and at the same time controls the CPTU probe 8 to move on the positioning track 6 to the measurement positioning line 17 corresponding to the load, and to be located at the corresponding measurement point 18.
  • the model pile axial force under the load and the CPTU measurement value analyze and evaluate the soil plugging effect of the pile foundation. Specifically, according to the soil plugging effect of the pile foundation under different loads, The axial force of the model pile 3 and the CPTU measurement values of the test soil 2 at the three measurement points 18, combined with the CPTU benchmark value of the test soil 2 before the pile is pressed in step A2, can be used to determine the soil plugging effect of the pile foundation. Perform analysis.
  • the model pile 3 can be an open pile or a closed pile. By changing the type of the model pile 3, the soil squeezing effect of different pile types can be studied.
  • Both evaluation models perform the following operations: according to the test requirements, apply the prescribed load to the model pile 3 through the loading system 4, drill the model pile 3 into the test soil 2, and obtain the axial force of the model pile 3 through the axial force detection system.
  • the CPTU measurement system obtain the CPTU measurement value of the test soil 2 at the measurement point 18 on a certain measurement positioning line 17 under the load.
  • the pile pressure load for the model test is designed according to a similar theory.
  • the loading system 4 applies load to the model pile 3 in a graded static loading manner. It can also be cyclic dynamic loading to study the influence of different loads on the soil plug effect of offshore wind power pile foundations.
  • the CPTU probe 8 is used to measure the sample soil at three measurement points 18 on a measurement positioning line 17 at each level of load.
  • the evaluation model design method and evaluation method of the present invention are used for offshore wind power pile foundations and can also be used for pile foundations in other applications.
  • CPTU data has high accuracy and large quantity, which can directly reflect the properties of foundation soil and facilitate the assessment of soil congestion effects.
  • the types of variables that can be set in the model include pile type, load direction, type, duration, etc., which facilitates the study of the impact of different factors on the properties of pile foundations.
  • the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

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Abstract

一种海上风电桩基土塞挤土效应的评估模型设计及评估方法，包括以下步骤:S1、设置模型箱（1），设计模型试验的相似比，确定模型桩（3）的尺寸；S2、在模型箱（1）中设置桩安装位（13），设置第一测量定位圆（14）、第二测量定位圆（15）和第三测量定位圆（16），沿桩安装位（13）径向设置测量定位线（17），与三个测量定位圆的交叉位置作为测量点位（18）；S3、在模型箱（1）中按照规定要求填装试验用土（2）；S4、安装CPTU测量系统，CPTU探头（8）设置在测量定位线（17）上的测量点位（18）处，CPTU探头（8）与CPTU数据采集仪（10）连接，CPTU贯入机构（7）用于将CPTU探头（8）贯入到试验用土（2）中；CPTU数据采集仪（10）与计算机（11）连接；S5、安装模型桩（3）、加载系统（4）和轴力检测系统，模型桩（3）设置在桩安装位（13）处，加载系统（4）用于对模型桩（3）施加载荷，轴力检测系统用于检测模型桩（3）的轴力。

Description

海上风电桩基土塞挤土效应的评估模型设计及评估方法 技术领域
本发明涉及岩土工程领域，具体涉及一种海上风电桩基土塞挤土效应的评估模型设计及评估方法。
背景技术
在开发利用绿色能源的发展趋势下，海上风电作为一种清洁能源，有着能量效益高、占用土地资源少等不可替代的优势，正在世界范围内快速发展。海上风电机往往采用单桩基础，桩基的土塞及挤土效应是影响桩基安全性与稳定性的重要因素。传统桩基常用的土压力及孔隙水压力评估方法存在数据采集难，有效性差等缺点。
而静力触探系统(cone penetration test,CPTU)是岩土工程领域一种重要的原位测试技术,目前主要用于土层划分、场地液化判别、地基土层的物理力学参数估算、地基承载力的评定、桩基承载力估算等。尤其孔压静力触探(piezocone penetration test,CPTU)，目前是海上风电桩基工程设计参数的重要参考依据。具有直观、快速及数据连续性等优点。可以在现场直接得到测试土层的贯入阻力等指标，直观反应桩周围土的物理力学性能。
在现有技术中，由于海上的复杂环境，开展针对海上风电桩基的现场承载力试验等原位测试往往存在较大困难，取得的数据也因影响因素过多而难以分析，尤其对海上桩基承载力影响较大的土塞、挤土等效应很难直接得到有效评估。
发明内容
鉴于以上所述现有技术的缺点，本发明要解决的技术问题在于提供一种海上风电桩基土塞挤土效应的评估模型设计及评估方法，采取模型试验方式，能够方便、准确、系统地评估桩基的土塞挤土效应，影响因素可控，成本低。
为实现上述目的，本发明提供一种海上风电桩基土塞挤土效应的评估模型设计方法，包括以下步骤:
S1、设置模型箱，根据桩基实物与模型箱尺寸设计模型试验的相似比，确定模型桩的尺寸；
S2、在模型箱中设置桩安装位，并以桩安装位中心为圆心设置第一测量定位圆、第二测量定位圆和第三测量定位圆，且第一测量定位圆、第二测量定位圆和第三测量定位圆直径分别为1D～2D、5D～6D和6D～10D；沿桩安装位径向设置测量定位线，测量定位线与第一测 量定位圆、第二测量定位圆和第三测量定位圆交叉位置作为测量点位；
S3、在模型箱中按照规定要求填装试验用土；
S4、安装CPTU测量系统，包括CPTU贯入机构、CPTU探头和CPTU数据采集仪，CPTU探头设置在测量定位线上的测量点位处，CPTU探头与CPTU数据采集仪连接，CPTU贯入机构用于将CPTU探头贯入到试验用土中；CPTU数据采集仪与计算机连接；
S5、安装模型桩、加载系统和轴力检测系统，模型桩设置在桩安装位，加载系统与模型桩连接，用于对模型桩施加载荷，轴力检测系统用于检测模型桩的轴力，轴力检测系统与计算机连接。
进一步地，所述步骤S2中，桩安装位位于模型箱正中心。
进一步地，所述步骤S2中，测量定位线数量为偶数，且测量定位线绕桩安装位均匀分布，每条测量定位线用于模型桩在某一级载荷下的测量。
进一步地，所述步骤S2中，测量点位之间的距离L大于10d，其中d为用于在测量点位进行测量的CPTU探头的直径。
进一步地，所述步骤S3中，根据土工试验方法标准GB/T 50123-2019制备试验用土，填土均匀密实，并充分饱和。
进一步地，所述步骤S4中，CPTU测量系统还包括定位轨道，定位轨道安装在测量定位线上方，CPTU探头安装于定位轨道，并能够在定位轨道上移动至测量点位。
进一步地，所述步骤S5中，轴力检测系统包括光纤传感器和光纤数据采集仪，光纤传感器安装于模型桩中，光纤传感器与光纤数据采集仪连接，光纤数据采集仪与计算机连接。
本发明还提供一种海上风电桩基土塞挤土效应的评估方法，包括以下内容：
A、桩基挤土效应评估，包括以下步骤：
A1、采用上述的评估模型设计方法，设置评估模型；
A2、模型桩未钻入试验用土前，通过CPTU测量系统，获取试验用土的CPTU基准值；
A3、根据试验要求，通过加载系统对模型桩施加规定载荷，模型桩钻入试验用土中，并通过轴力检测系统获取模型桩轴力，通过CPTU测量系统，获取该载荷下某一测量定位线上的测量点位处试验用土的CPTU测量值；
A4、根据载荷、以及该载荷下的模型桩轴力和CPTU测量值，分析评估桩基的土塞挤土效应；
B、桩基土塞效应评估，包括以下步骤：
B1、采用上述的评估模型设计方法，设置两种评估模型，两种评估模型的区别为模型桩 类型不同，分别采用开口桩和闭口桩；
B2、两种评估模型都进行如下操作：根据试验要求，通过加载系统对模型桩施加规定载荷，模型桩钻入试验用土中，并通过轴力检测系统获取模型桩轴力，通过CPTU测量系统，获取该载荷下某一测量定位线上的测量点位处试验用土的CPTU测量值；
B3、对比两组评估模型获得的CPTU测量值，评估土塞效应。
进一步地，所述步骤A3和步骤B2中，加载系统对模型桩施加载荷的方式包括分级静力加载或循环动力加载，荷载方向包括水平方向和竖直方向。
进一步地，所述步骤A3和步骤B2中，加载系统对模型桩进行分级静力加载，每级载荷时都通过CPTU测量系统分别在一条测量定位线的测量点位上进行测量。
如上所述，本发明涉及的评估模型设计方法、以及评估方法，具有以下有益效果：
1)通过设计模型试验来评估海上风电桩基的土塞挤土效应，相比现场试验成本低，影响因素可控，能够方便、准确、系统评估海上风电桩基土塞挤土效应，避免了在海上现场测试的困难。
2)CPTU数据精度高，数量大，能够直接反映地基土的性质，便于评估土塞挤土效应。
3)模型可设置的变量种类包括桩型、荷载方向、种类、持续时间等，便于研究不同因素对桩基性质的影响。
4)模型桩加载与CPTU贯入过程可均通过计算机自动化控制，试验操作简单。
附图说明
图1为本发明所设计的评估模型的示意图。
图2为本发明中的测量定位线和测量点位的位置示意图。
元件标号说明
1                 模型箱
2                 试验用土
3                 模型桩
4                 加载系统
5                 光纤传感器
6                 定位轨道
7                 CPTU贯入机构
8                 CPTU探头
9                 光纤数据采集仪
10                CPTU数据采集仪
11                计算机
12                桁架
13                桩安装位
14                第一测量定位圆
15                第二测量定位圆
16                第三测量定位圆
17                测量定位线
18                测量点位
具体实施方式
以下由特定的具体实施例说明本发明的实施方式，熟悉此技术的人士可由本说明书所揭露的内容轻易地了解本发明的其他优点及功效。
须知，本说明书附图所绘的结构、比例、大小等，均仅用以配合说明书所揭示的内容，以供熟悉此技术的人士了解与阅读，并非用以限定本发明可实施的限定条件，故不具技术上的实质意义，任何结构的修饰、比例关系的改变或大小的调整，在不影响本发明所能产生的功效及所能达成的目的下，均应仍落在本发明所揭示的技术内容能涵盖的范围内。同时，本说明书中所引用的如“上”、“下”、“左”、“右”、“中间”等的用语，亦仅为便于叙述明了，而非用以限定本发明可实施的范围，其相对关系的改变或调整，在无实质变更技术内容下，当亦视为本发明可实施的范畴。
参见图1至图2，本发明提供了一种海上风电桩基土塞挤土效应的评估模型设计方法，评估模型包括模型箱1、试验用土2、模型桩3、加载系统4、CPTU测量系统、轴力检测系统等结构。评估模型设计方法包括以下步骤：
S1、设置模型箱1，模型箱1的尺寸根据实际情况选择合适尺寸，根据桩基实物与模型箱尺寸设计模型试验的相似比，确定模型桩3的尺寸，包括模型桩3半径D，制作好模型桩3。
S2、在模型箱1中设定用于模型桩3的桩安装位13，桩安装位13为圆形区域，并以桩安装位13中心为圆心设置第一测量定位圆14、第二测量定位圆15和第三测量定位圆16，且第一测量定位圆14、第二测量定位圆15和第三测量定位圆16直径分别为1D～2D、5D～6D 和6D～10D，D为模型桩3的直径。桩安装位13优选位于模型箱1正中心处。第一测量定位圆14、第二测量定位圆15和第三测量定位圆16分别代表模型桩3的桩身附近、塑性区边缘和塑性区外三个位置区域。
沿桩安装位13径向设置直线作为测量定位线17，测量定位线17与第一测量定位圆14、第二测量定位圆15和第三测量定位圆16交叉位置作为测量点位18，测量点位18用于CPTU测量系统的CPTU探头8的测量定位。测量定位线17的数量根据模型桩3加载载荷的情况(包括荷载分级、荷载循环时间等因素)设置，测量定位线17数量优选为偶数，参见图2，在本实施例中，测量定位线17为四条，四条测量定位线17绕桩安装位13均匀分布，也即测量定位线17之间间隔90°，两两相对称，将四条测量定位线17分别用于模型桩3在P1～P4级载荷下的测量，对应地将四条测量定位线17分别编号为P1～P4，对于任一编号Pn的测量定位线，其上的测量点位18从内向外分别编号为Pn-1、Pn-2和Pn-3。
优选地，测量点位18之间的距离L大于10d，具体地，同一测量定位线17上的测量点位18之间间距、以及不同测量定位线17上的测量点位18之间间距L都大于10d，d为CPTU探头8的直径，以确保后续利用CPTU测量系统的CPTU探头8进行测量时，CPTU探头8之间不会相互影响。
S3、在模型箱1中按照规定要求填装试验用土2；具体地，在本实施例中，取海上风电桩基所在海域的海床土，根据土工试验方法标准GB/T 50123-2019制备试验用土2，填土均匀、密实、并充分饱。
S4、安装CPTU测量系统，包括CPTU贯入机构7、CPTU探头8和CPTU数据采集仪10，CPTU探头8设置在测量定位线17上的测量点位18处，CPTU探头8与CPTU数据采集仪10连接，能够将所测量的数据传输到CPTU数据采集仪10中，CPTU贯入机构7用于将CPTU探头8贯入到试验用土2中；CPTU数据采集仪10与计算机11连接，能够将数据传输到计算机11中进行储存和分析计算。在本发明中，根据模拟箱的大小选择CPTU测量系统的各个部分的尺寸，由于评估模型通常在室内完成，选择微型的CPTU测量系统。
作为优选设计，在本实施例中，CPTU测量系统还包括定位轨道6，定位轨道6安装在测量定位线17上方，CPTU探头8安装于定位轨道6，并能够在定位轨道6上移动至测量点位18，定位轨道6具体地包括四个水平轨道和切换轨道，四个水平轨道分别设置在四条测量定位线17正上方，并与测量定位线17相平行，CPTU探头8能够在水平轨道上移动至不同测量点位18，切换轨道连接各个水平轨道，用于CPTU探头8从一个水平轨道移动至一个水平轨道上。CPTU探头8在定位轨道6上的移动由计算机11控制，计算机课根据加载情况，控 制CPTU探头8移动到对应的测量定位线17处。
S5、安装模型桩3、加载系统4和轴力检测系统，模型桩3设置在桩安装位13处，加载系统4与模型桩3连接，用于对模型桩3施加载荷，所施加的载荷包括横向和竖向的载荷。加载系统4能够使模型桩3钻入到试验用土2，以及对已钻入到试验用土2的模型桩3施加多种载荷。轴力检测系统用于检测模型桩3的轴力，轴力检测系统与计算机11连接，能够将检测数据传输给计算机11进行储存和计算分析。
在本实施例中，加载系统4安装在模型箱1上方的桁架12上，与模型桩3牢固连接，具有满足试验要求的动力系统，由计算机11控制加载的启停、以及载荷的大小和加载方式。轴力检测系统包括光纤传感器5和光纤数据采集仪9，光纤传感器5安装于模型桩3中，在试验过程中连续性监测模型桩3的轴向力；光纤传感器5与光纤数据采集仪9连接，光纤数据采集仪9与计算机11连接。当然，在其他实施例中，轴力检测系统也可以为其他合适结构，能够实现上述实时监测模型桩3的轴向力即可。
本发明的评估模型设计方法，能够用于桩基土塞挤土效应的评估，采取模型试验方式，基于孔压静力触探(CPTU)技术，能够方便、准确、系统地评估桩基的土塞挤土效应，相对于在现场，影响因素可控，成本低。
本发明还提供了一种海上风电桩基土塞挤土效应的评估方法，包括桩基挤土效应评估和桩基土塞效应评估两部分内容，具体如下：
A、桩基挤土效应评估，包括以下步骤A1～A4：
A1、采用上所述的评估模型设计方法，设置评估模型。在本实施例中，评估模型中测量定位线17设置为多个，并为偶数个，数量为偶数，且测量定位线17绕桩安装位13均匀分布。
A2、模型桩3未钻入试验用土2前，通过CPTU测量系统进行测量，,获取试验用土2的各项物理参数，包括锥尖阻力、侧壁摩阻力、孔隙水压力等参数，作为试验用土2的CPTU基准值。
A3、根据试验要求，通过加载系统4对模型桩3施加规定载荷，模型桩3钻入试验用土2中，并通过轴力检测系统获取模型桩3轴力，通过CPTU测量系统，获取该载荷下某一测量定位线17上的测量点位18处试验用土2的各项物理参数，作为试验用土2的CPTU测量值，轴力数据和CPTU测量系统的CPTU测量值都传输到计算机11中。
具体地，根据实际桩基受到的轴向荷载，按照相似理论设计模型试验的压桩荷载，其中，加载系统4对模型桩3施加载荷的方式，可以是分级静力加载，也可以是循环动力加载，以研究不同荷载对海上风电桩基挤土效应的影响。采用分级静力加载方式时，每级载荷时都利 用CPTU探头8在一条测量定位线17上的三个测量点位18处的试样用土中进行测量，参见图2，在本实施例中，将压桩荷载分为4级，记为载荷P1～载荷P4，P1级载荷压桩时，CPTU探头8对P1-1、P1-2、P1-3点位进行测试，记录锥尖阻力、侧壁摩阻力、孔隙水压力等参数，同时通过光纤传感器5监测模型桩3的轴力。然后按照相同方式依此加载P2～P4载荷，对应在P2～P4测量定位线17上的三个测量点位18处进行测量，完成压桩试验。在试验过程中，计算机控制加载系统4改变载荷，同时控制CPTU探头8在定位轨道6上移动至与该载荷对应的测量定位线17上，并位于对应测量点位18处。
A4、根据载荷、以及该载荷下的模型桩轴力和CPTU测量值，分析评估桩基的土塞挤土效应，分析评估桩基的土塞挤土效应；具体地，根据在不同载荷下的模型桩3轴力和试验用土2在三个测量点位18处的CPTU测量值，并结合步骤A2中未压桩前的试验用土2的CPTU基准值，可以对桩基的土塞挤土效应进行分析。
在桩基挤土效应评估中，模型桩3可采用开口桩或闭口桩，通过更换模型桩3类型，可研究不同桩型的挤土效应。
B、桩基土塞效应评估，包括以下步骤：
B1、采用上述的评估模型设计方法，设置两种评估模型，两种评估模型的区别为模型桩3类型不同，分别采用开口桩和闭口桩，其余结构都相同。
B2、两种评估模型都进行如下操作：根据试验要求，通过加载系统4对模型桩3施加规定载荷，模型桩3钻入试验用土2中，并通过轴力检测系统获取模型桩3轴力，通过CPTU测量系统，获取该载荷下某一测量定位线17上的测量点位18处试验用土2的CPTU测量值。在本步骤中，具体地，根据实际桩基受到的轴向荷载，按照相似理论设计模型试验的压桩荷载，其中，加载系统4对模型桩3施加载荷的方式，可以是分级静力加载，也可以是循环动力加载，以研究不同荷载对海上风电桩基土塞效应的影响。采用分级静力加载方式时，每级载荷时都利用CPTU探头8在一条测量定位线17上的三个测量点位18处的试样用土中进行测量。
B3、对比两组评估模型获得的CPTU测量值，评估土塞效应，也即在其他条件相同的情况下，通过对比开口桩和闭口桩两种桩基的CPTU测量值，来评估土塞效应。
本发明的评估模型设计方法和评估方法，用于海上风电桩基，也可以用于其他应用场合的桩基。
由上可知，与现有技术相比，本发明具有以下有益效果：
1)通过设计模型试验来评估海上风电桩基的土塞挤土效应，相比现场试验成本低，影响因素可控，能够方便、准确、系统评估海上风电桩基土塞挤土效应，避免了在海上现场测试的困难。
2)CPTU数据精度高，数量大，能够直接反映地基土的性质，便于评估土塞挤土效应。
3)模型可设置的变量种类包括桩型、荷载方向、种类、持续时间等，便于研究不同因素对桩基性质的影响。
4)模型桩3加载与CPTU贯入过程可均通过计算机11自动化控制，试验操作简单。
综上所述，本发明有效克服了现有技术中的种种缺点而具有高度产业利用价值。
上述实施例仅例示性说明本发明的原理及其功效，而非用于限制本发明。任何熟悉此技术的人士皆可在不违背本发明的精神及范畴下，对上述实施例进行修饰或改变。因此，举凡所属技术领域中具有通常知识者在未脱离本发明所揭示的精神与技术思想下所完成的一切等效修饰或改变，仍应由本发明的权利要求所涵盖。

Claims (10)

  1. 一种海上风电桩基土塞挤土效应的评估模型设计方法，其特征在于：包括以下步骤:
    S1、设置模型箱(1)，根据桩基实物与模型箱(1)尺寸设计模型试验的相似比，确定模型桩(3)的尺寸；
    S2、在模型箱(1)中设置桩安装位(13)，并以桩安装位(13)中心为圆心设置第一测量定位圆(14)、第二测量定位圆(15)和第三测量定位圆(16)，且第一测量定位圆(14)、第二测量定位圆(15)和第三测量定位圆(16)直径分别为1D～2D、5D～6D和6D～10D；沿桩安装位(13)径向设置测量定位线(17)，测量定位线(17)与第一测量定位圆(14)、第二测量定位圆(15)和第三测量定位圆(16)交叉位置作为测量点位(18)；
    S3、在模型箱(1)中按照规定要求填装试验用土(2)；
    S4、安装CPTU测量系统，包括CPTU贯入机构(7)、CPTU探头(8)和CPTU数据采集仪(10)，CPTU探头(8)设置在测量定位线(17)上的测量点位(18)处，CPTU探头(8)与CPTU数据采集仪(10)连接，CPTU贯入机构(7)用于将CPTU探头(8)贯入到试验用土(2)中；CPTU数据采集仪(10)与计算机(11)连接；
    S5、安装模型桩(3)、加载系统(4)和轴力检测系统，模型桩(3)设置在桩安装位(13)，加载系统(4)与模型桩(3)连接，用于对模型桩(3)施加载荷，轴力检测系统用于检测模型桩(3)的轴力，轴力检测系统与计算机(11)连接。
  2. 根据权利要求1所述的评估模型设计方法，其特征在于：所述步骤S2中，桩安装位(13)位于模型箱(1)正中心。
  3. 根据权利要求1所述的评估模型设计方法，其特征在于：所述步骤S2中，测量定位线(17)数量为偶数，且测量定位线(17)绕桩安装位(13)均匀分布，每条测量定位线(17)用于模型桩(3)在某一级载荷下的测量。
  4. 根据权利要求1所述的评估模型设计方法，其特征在于：所述步骤S2中，测量点位(18)之间的距离L大于10d，其中d为用于在测量点位(18)进行测量的CPTU探头(8)的直径。
  5. 根据权利要求1所述的评估模型设计方法，其特征在于：所述步骤S3中，根据土工试验方法标准GB/T 50123-2019制备试验用土(2)，填土均匀密实，并充分饱和。
  6. 根据权利要求1所述的评估模型设计方法，其特征在于：所述步骤S4中，CPTU测量系统还包括定位轨道(6)，定位轨道(6)安装在测量定位线(17)上方，CPTU探头(8)安装于定位轨道(6)，并能够在定位轨道(6)上移动至测量点位(18)。
  7. 根据权利要求1所述的评估模型设计方法，其特征在于：所述步骤S5中，轴力检测系统包括光纤传感器(5)和光纤数据采集仪(9)，光纤传感器(5)安装于模型桩(3)中，光纤传感器(5)与光纤数据采集仪(9)连接，光纤数据采集仪(9)与计算机(11)连接。
  8. 一种海上风电桩基土塞挤土效应的评估方法，其特征在于：包括以下内容：
    A、桩基挤土效应评估，包括以下步骤：
    A1、采用如权利要求1至7任一所述的评估模型设计方法，设置评估模型；
    A2、模型桩(3)未钻入试验用土(2)前，通过CPTU测量系统，获取试验用土(2)的CPTU基准值；
    A3、根据试验要求，通过加载系统(4)对模型桩(3)施加规定载荷，模型桩(3)钻入试验用土(2)中，并通过轴力检测系统获取模型桩(3)轴力，通过CPTU测量系统，获取该载荷下某一测量定位线(17)上的测量点位(18)处试验用土(2)的CPTU测量值；
    A4、根据载荷、以及该载荷下的模型桩(3)轴力和CPTU测量值，分析评估桩基的土塞挤土效应；
    B、桩基土塞效应评估，包括以下步骤：
    B1、采用如权利要求1至7任一所述的评估模型设计方法，设置两种评估模型，两种评估模型的区别为模型桩(3)类型不同，分别采用开口桩和闭口桩；
    B2、两种评估模型都进行如下操作：根据试验要求，通过加载系统(4)对模型桩(3)施加规定载荷，模型桩(3)钻入试验用土(2)中，并通过轴力检测系统获取模型桩(3)轴力，通过CPTU测量系统，获取该载荷下某一测量定位线(17)上的测量点位(18)处试验用土(2)的CPTU测量值；
    B3、对比两组评估模型获得的CPTU测量值，评估土塞效应。
  9. 根据权利要求8所述的评估方法，其特征在于：所述步骤A3和步骤B2中，加载系统(4)对模型桩(3)施加载荷的方式包括分级静力加载或循环动力加载，荷载方向包括水平方向和竖直方向。
  10. 根据权利要求9所述的评估方法，其特征在于：所述步骤A3和步骤B2中，加载系统(4)对模型桩(3)进行分级静力加载，每级载荷时都通过CPTU测量系统分别在一条测量定位线(17)的测量点位(18)上进行测量。
PCT/CN2023/089878 2022-09-23 2023-04-21 海上风电桩基土塞挤土效应的评估模型设计及评估方法 WO2024060608A1 (zh)

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