CN114439056B - A system for detecting the bearing capacity of pile foundations using distributed piezoelectric cable impedance sensing technology and its construction and detection methods - Google Patents

A system for detecting the bearing capacity of pile foundations using distributed piezoelectric cable impedance sensing technology and its construction and detection methods Download PDF

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CN114439056B
CN114439056B CN202210084477.7A CN202210084477A CN114439056B CN 114439056 B CN114439056 B CN 114439056B CN 202210084477 A CN202210084477 A CN 202210084477A CN 114439056 B CN114439056 B CN 114439056B
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piezoelectric cable
distributed
pile
pile body
cable
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CN114439056A (en
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王军
吴超越
刘志明
金锦强
金海胜
吕有畅
倪俊峰
蔡良洁
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Wenzhou University
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    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D33/00Testing foundations or foundation structures
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D15/00Handling building or like materials for hydraulic engineering or foundations
    • E02D15/02Handling of bulk concrete specially for foundation or hydraulic engineering purposes
    • E02D15/04Placing concrete in mould-pipes, pile tubes, bore-holes or narrow shafts
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D15/00Handling building or like materials for hydraulic engineering or foundations
    • E02D15/08Sinking workpieces into water or soil inasmuch as not provided for elsewhere
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D27/00Foundations as substructures
    • E02D27/10Deep foundations
    • E02D27/12Pile foundations
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D5/00Bulkheads, piles, or other structural elements specially adapted to foundation engineering
    • E02D5/22Piles
    • E02D5/34Concrete or concrete-like piles cast in position ; Apparatus for making same
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02GINSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
    • H02G9/00Installations of electric cables or lines in or on the ground or water
    • H02G9/02Installations of electric cables or lines in or on the ground or water laid directly in or on the ground, river-bed or sea-bottom; Coverings therefor, e.g. tile
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D2600/00Miscellaneous
    • E02D2600/10Miscellaneous comprising sensor means

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Abstract

The invention discloses a system for detecting pile foundation bearing capacity by using a distributed piezoelectric cable impedance sensing technology, which is characterized in that: including multichannel impedance analyzer and distributed piezoelectric cable, distributed piezoelectric cable distributes along pile length direction and embeds in the pile body, distributed piezoelectric cable encircles pile body evenly distributed at least three, distributed piezoelectric cable and multichannel impedance analyzer electrical signal connection, distributed piezoelectric cable includes piezoelectric cable, piezoelectric cable wire and switch switching device, wherein piezoelectric cable and piezoelectric cable wire parallel distribution, a plurality of departments set up control switch switching device between piezoelectric cable wire and the piezoelectric cable, through the position that the multichannel impedance analyzer is to be detected of switch switching device control multichannel impedance analyzer, distributed piezoelectric cable wholly adopt the crust parcel constraint. The construction method and the detection method of the system are also disclosed. The system has stronger anti-skid capability and lower cost.

Description

利用分布式压电电缆阻抗传感技术检测桩基承载力的系统及 其施工和检测方法The system and application of distributed piezoelectric cable impedance sensing technology to detect the bearing capacity of pile foundation Its construction and testing methods

技术领域technical field

本发明涉及桩基工程领域和压电阻抗技术领域,特别涉及一种利用分布式压电电缆阻抗传感技术检测桩基承载力的系统。本发明还涉及一种利用分布式压电电缆阻抗传感技术检测桩基承载力的系统的施工方法。本发明还涉及一种利用分布式压电电缆阻抗传感技术检测桩基承载力的系统的检测方法。The invention relates to the field of pile foundation engineering and the field of piezoelectric impedance technology, in particular to a system for detecting the bearing capacity of pile foundation by using distributed piezoelectric cable impedance sensing technology. The invention also relates to a construction method of a system for detecting the bearing capacity of a pile foundation by using a distributed piezoelectric cable impedance sensing technology. The invention also relates to a detection method of a system for detecting the bearing capacity of a pile foundation by using the distributed piezoelectric cable impedance sensing technology.

背景技术Background technique

桩基工程是建筑基础的重要组成部分,在施工过程中桩基施工质量的好坏对桩基承载力影响很大,在运维过程中桩基的稳定直接影响到上部建筑物的稳定和使用者的人身安全,所以对桩基工程施工过程中和长期运维过程中的检测变得尤为重要。但现场施工和运维过程中环境复杂,桩基础数据采集环境恶劣,对桩基的检测提出了更高的要求。只有准确检测桩基承载力的变化过程,将检测信号及时的传递并做出分析与预警,对实际工程中可能出现的基础破坏及时地进行预警,才能更好地完善对桩基施工过程中和运维过程中承载特性的研究。The pile foundation project is an important part of the building foundation. During the construction process, the construction quality of the pile foundation has a great influence on the bearing capacity of the pile foundation. The stability of the pile foundation directly affects the stability and use of the superstructure during the operation and maintenance process. Therefore, it is particularly important to detect during the construction of pile foundation projects and during long-term operation and maintenance. However, the environment in the on-site construction and operation and maintenance process is complex, and the pile foundation data collection environment is harsh, which puts forward higher requirements for the detection of pile foundations. Only by accurately detecting the change process of pile foundation bearing capacity, transmitting the detection signal in time and making analysis and early warning, and timely warning of possible foundation damage in actual engineering, can we better improve the monitoring of pile foundation construction process and Research on bearing characteristics during operation and maintenance.

当前检测混凝土灌注桩和PHC管桩,常用的检测方法为钢筋计、电阻式应变片、光纤光栅和分布式光纤等。最常用的是光纤光栅和分布式光纤。但分布式光纤有很多缺点:(1)分布式光纤光纤解调仪价格贵、尺寸较大、受国外技术垄断;(2)空气或灰尘进入法兰盘导致激光无法传输从而损耗光纤信号;(3)光纤较为脆弱,需要外层钢绞线保护等。At present, the commonly used detection methods for detecting concrete pouring piles and PHC pipe piles are steel bar gauges, resistive strain gauges, optical fiber Bragg gratings, and distributed optical fibers. The most commonly used are fiber gratings and distributed fibers. However, distributed optical fibers have many disadvantages: (1) Distributed optical fiber demodulators are expensive, large in size, and monopolized by foreign technologies; (2) Air or dust enters the flange, causing the laser to fail to transmit and loss of optical fiber signals; ( 3) The optical fiber is relatively fragile and needs to be protected by an outer layer of steel strands.

压电电缆从内到外由四层构成,分别为合金、PVDF铜丝和聚乙烯保护层。压电电缆具有高的抗拉伸强度,PVDF压电电缆的工作环境温度范围很广,在-20摄氏度至50摄氏度范围内。压电系数g33基本保持不变。如今,压电电缆多应用在车流量检测等方面,在桩基检测等周界安全检测应用比较少。而压电电缆的阻抗与作用力成线性关系,在周界安全检测方面有很大的应用前景。The piezoelectric cable consists of four layers from the inside to the outside, which are alloy, PVDF copper wire and polyethylene protective layer. Piezoelectric cables have high tensile strength, and the operating temperature range of PVDF piezoelectric cables is very wide, ranging from -20 degrees Celsius to 50 degrees Celsius. The piezoelectric coefficient g 33 remains basically unchanged. Nowadays, piezoelectric cables are mostly used in traffic flow detection and other aspects, but are rarely used in perimeter safety detection such as pile foundation detection. However, the impedance of the piezoelectric cable has a linear relationship with the force, so it has great application prospects in perimeter security detection.

发明内容Contents of the invention

本发明的目的在于提供一种利用分布式压电电缆阻抗传感技术检测桩基承载力的系统,该系统的防滑能力更强且成本更低。本发明的目的还包括提供一种利用分布式压电电缆阻抗传感技术检测桩基承载力的系统的施工方法。本发明目的还包括提供一种利用分布式压电电缆阻抗传感技术检测桩基承载力的系统的检测方法。The purpose of the present invention is to provide a system for detecting the bearing capacity of pile foundations using distributed piezoelectric cable impedance sensing technology, which has stronger anti-skid ability and lower cost. The object of the present invention also includes providing a construction method of a system that utilizes distributed piezoelectric cable impedance sensing technology to detect the bearing capacity of pile foundations. The object of the present invention also includes providing a detection method of a system for detecting the bearing capacity of a pile foundation by using the distributed piezoelectric cable impedance sensing technology.

为实现上述目的,本发明提供如下技术方案:To achieve the above object, the present invention provides the following technical solutions:

一种利用分布式压电电缆阻抗传感技术检测桩基承载力的系统,其特征是:包括多通道阻抗分析仪和分布式压电电缆,分布式压电电缆沿桩体长度方向分布且内置于桩体内,分布式压电电缆环绕桩体均匀分布至少三条,分布式压电电缆与多通道阻抗分析仪电信号连接,分布式压电电缆包括压电电缆、压电电缆导线和开关交换装置,其中压电电缆和压电电缆导线平行分布,压电电缆导线与压电电缆之间多处设置开关交换装置,通过所述开关交换装置控制多通道阻抗分析仪所要检测的位置,所述的分布式压电电缆整体采用外皮包裹约束。A system for detecting the bearing capacity of pile foundations using distributed piezoelectric cable impedance sensing technology, which is characterized in that it includes a multi-channel impedance analyzer and distributed piezoelectric cables, distributed along the length of the pile body and built-in In the pile body, at least three distributed piezoelectric cables are evenly distributed around the pile body, and the distributed piezoelectric cables are connected to the electrical signal of the multi-channel impedance analyzer. The distributed piezoelectric cables include piezoelectric cables, piezoelectric cable conductors and switching devices , wherein the piezoelectric cable and the piezoelectric cable conductors are distributed in parallel, and a switch exchange device is arranged between the piezoelectric cable conductor and the piezoelectric cable, and the position to be detected by the multi-channel impedance analyzer is controlled by the switch exchange device. The distributed piezoelectric cable is restrained by sheath wrapping as a whole.

优选的,所述桩体为PHC管桩,PHC管桩表面沿桩身表面预先设计所要测试的路线开设有布线槽,所述分布式压电电缆置入在布线槽内并采用胶凝材料固化封装,每个测试截面间隔90°布设四组所述分布式压电电缆。Preferably, the pile body is a PHC pipe pile, and the surface of the PHC pipe pile is provided with a wiring groove along the pre-designed route to be tested on the surface of the pile body, and the distributed piezoelectric cable is placed in the wiring groove and solidified with a cementitious material For packaging, four groups of the distributed piezoelectric cables are laid out at intervals of 90° in each test section.

优选的,所述桩体为灌注桩,灌注桩钢筋笼上沿截面间隔90°均匀分布的4根纵筋上通过扎丝和环氧树脂各固定一根分布式压电电缆。Preferably, the pile body is a cast-in-place pile, and the steel cage of the cast-in-place pile is fixed with a distributed piezoelectric cable by wire binding and epoxy resin on the four longitudinal reinforcements uniformly distributed along the cross-section at intervals of 90°.

本发明还提供上述利用分布式压电电缆阻抗传感技术检测桩基承载力的系统的施工方法,其特征是:包括以下步骤:The present invention also provides the construction method of the system for detecting the bearing capacity of the pile foundation by using the distributed piezoelectric cable impedance sensing technology, which is characterized in that it includes the following steps:

(1)电缆埋设:将分布式压电电缆环绕式埋入桩体内,每个检测截面环绕间隔90°布设四组所述分布式压电电缆,在分布式压电电缆埋入后采取定点固定;(1) Cable embedding: The distributed piezoelectric cables are buried in the pile body in a surrounding manner, and four groups of the distributed piezoelectric cables are laid around each detection section at an interval of 90°, and fixed points are fixed after the distributed piezoelectric cables are buried. ;

(2)数据采集线路连接:压电电缆导线的端头与多通道阻抗分析仪连接组成分布式压电电缆阻抗传感技术检测桩体的桩基承载力的系统进行数据采集。(2) Data acquisition line connection: The end of the piezoelectric cable conductor is connected with the multi-channel impedance analyzer to form a distributed piezoelectric cable impedance sensing technology to detect the pile foundation bearing capacity of the pile body for data acquisition.

优选的,所述桩体为PHC管桩,其施工步骤包括:Preferably, the pile body is a PHC pipe pile, and its construction steps include:

(1)开槽布线:沿桩身表面预先设计所要测试的路线,后用切割工具沿设计路线进行开槽,其深度和宽度以能放入分布式压电电缆为准,每个检测截面环绕间隔90°布设四组所述分布式压电电缆,在分布式压电电缆埋入后采取定点固定;(1) Slotted wiring: pre-design the route to be tested along the surface of the pile body, and then use a cutting tool to slot along the designed route. The depth and width are subject to the distributed piezoelectric cables. Each detection section is surrounded Lay four groups of distributed piezoelectric cables at intervals of 90°, and fix them at fixed points after the distributed piezoelectric cables are embedded;

(2)涂胶防护:布线槽使用环氧树脂进行填充、粘贴和表面保护;(2) Glue protection: the wiring groove is filled, pasted and surface protected with epoxy resin;

(3)数据采集线路连接:压电电缆导线的端头与多通道阻抗分析仪连接组成分布式压电电缆阻抗传感技术检测PHC管桩桩基承载力的系统进行数据采集。(3) Data acquisition line connection: The end of the piezoelectric cable conductor is connected with the multi-channel impedance analyzer to form a distributed piezoelectric cable impedance sensing technology to detect the bearing capacity of the PHC pipe pile foundation for data acquisition.

优选的,所述桩体为灌注桩,其施工步骤包括:Preferably, the pile body is a cast-in-place pile, and its construction steps include:

(1)埋设电缆:在灌注桩钢筋笼上沿截面间隔90°均匀分布的4根纵筋上通过扎丝和环氧树脂各固定一根分布式压电电缆;(1) Embedded cables: On the cast-in-place pile reinforcement cage, one distributed piezoelectric cable is fixed on the four longitudinal reinforcements evenly distributed along the cross-sectional interval of 90° by binding wire and epoxy resin;

(2)浇筑桩体:将绑扎有分布式压电电缆的灌注桩钢筋笼吊装入桩孔中,再灌注混凝土,使混凝土包裹住分布式压电电缆;(2) Pouring the pile body: hoist the cast-in-place pile reinforcement cage bound with the distributed piezoelectric cable into the pile hole, and then pour concrete so that the concrete wraps the distributed piezoelectric cable;

(3)数据采集线路连接:压电电缆导线的端头与多通道阻抗分析仪连接组成分布式压电电缆阻抗传感技术检测灌注桩桩基承载力的系统进行数据采集。(3) Data acquisition line connection: The end of the piezoelectric cable conductor is connected with a multi-channel impedance analyzer to form a distributed piezoelectric cable impedance sensing technology to detect the bearing capacity of the cast-in-situ pile foundation for data acquisition.

本发明提供的一种上述利用分布式压电电缆阻抗传感技术检测桩基承载力的系统的检测方法,在桩基承载力的作用下,桩身产生应力和应变,以使所述压电电缆传感器的阻抗发生变化,利用阻抗变化的输出信号判定灌注桩或PHC管桩的轴力变化,从而推算出灌注桩或PHC管桩的侧摩阻力和桩端承载力的变化,包括:The present invention provides a detection method for the above-mentioned system that uses distributed piezoelectric cable impedance sensing technology to detect the bearing capacity of pile foundation. Under the action of pile foundation bearing capacity, the pile body generates stress and strain, so that the piezoelectric The impedance of the cable sensor changes, and the output signal of the impedance change is used to determine the axial force change of the cast-in-situ pile or PHC pipe pile, so as to calculate the side friction resistance and pile end bearing capacity of the cast-in-place pile or PHC pipe pile, including:

(1)通过多通道阻抗分析仪测试得到压电电缆的轴向阻抗Z(h),由于阻抗的变化与应变成线性关系,从而推算出压电电缆的轴向应变ε(h),由于压电电缆固定在桩身表面,在静载力下,压电电缆轴向变形与桩身轴向一致,因此桩身应变也为应变ε(h),则桩身应力σ(h)为:(1) The axial impedance Z(h) of the piezoelectric cable is obtained by testing with a multi-channel impedance analyzer. Since the change of impedance has a linear relationship with the strain, the axial strain ε(h) of the piezoelectric cable is calculated. Since The piezoelectric cable is fixed on the surface of the pile body. Under the static load, the axial deformation of the piezoelectric cable is consistent with the axial direction of the pile body, so the strain of the pile body is also the strain ε(h), and the stress σ(h) of the pile body is:

σ(h)=ε(h)·Ec,其中,Ec为灌注桩的弹性模量。σ(h)=ε(h)·E c , where E c is the elastic modulus of the cast-in-place pile.

根据桩身应力σ(Z),桩身轴力Q(h)为:According to the pile body stress σ(Z), the pile body axial force Q(h) is:

Q(h)=σ(h)·A,其中A为桩身截面面积。Q(h)=σ(h)·A, where A is the cross-sectional area of the pile body.

(2)通过测试植入桩体内部压电电缆的阻抗变化,即可获得沿桩身不同荷载变形下分布式压电电缆的应变值,设ε1(h)和ε2(h)分别为测试得到的桩体在深度h处的沿水平荷载方向上对称部位的应变测试值,桩身应变一侧受拉一侧受压,则轴向压缩应变εa(h)和弯曲应变值εm(h)分别为:(2) By testing the impedance change of the piezoelectric cables implanted in the pile body, the strain values of the distributed piezoelectric cables under different load deformations along the pile body can be obtained, and ε 1 (h) and ε 2 (h) are respectively The strain test value of the symmetrical part of the pile body along the horizontal load direction at the depth h obtained from the test, the strain on one side of the pile body is under tension and the other side is under compression, then the axial compressive strain ε a (h) and the bending strain value ε m (h) are respectively:

Figure BDA0003485065630000041
Figure BDA0003485065630000041

优选的,所述多通道阻抗分析仪集发射和接收信号为一体,其测得的数值为频率为1kHz、电压为1V下多根压电电缆的阻抗变化;所述的多通道阻抗分析仪,具有控制开关检测交换装置的功能,能够实现开关命令发射。Preferably, the multi-channel impedance analyzer integrates transmitting and receiving signals, and the measured value is the impedance change of multiple piezoelectric cables with a frequency of 1 kHz and a voltage of 1 V; the multi-channel impedance analyzer, It has the function of controlling the switch to detect the switching device, and can realize the transmission of the switch command.

与现有技术相比,本发明的有益效果是:Compared with prior art, the beneficial effect of the present invention is:

(1)本发明中的压电电缆相比光纤价格更便宜,且压电电缆内部为实心,不受现场灰尘等影响,而分布式光纤内部易受灰尘、空气等影响,影响分布式光纤检测的准确性;(1) The piezoelectric cable in the present invention is cheaper than the optical fiber, and the piezoelectric cable is solid inside and is not affected by on-site dust, etc., while the distributed optical fiber is easily affected by dust, air, etc., which affects the distributed optical fiber detection accuracy;

(2)压电电缆本身有一层聚乙烯保护层,不易损坏,而分布式光纤较为脆弱,需要外层钢绞线保护;(2) The piezoelectric cable itself has a layer of polyethylene protective layer, which is not easy to damage, while the distributed optical fiber is relatively fragile and needs the protection of the outer steel strand;

(3)多通道阻抗分析仪对比于分布式光纤解调仪价格较为便宜,便携式多通道阻抗分析仪尺寸较光纤解调仪小,便于携带等优点,可实现对桩基承载力的大面积检测。(3) Compared with the distributed optical fiber demodulator, the multi-channel impedance analyzer is cheaper. The portable multi-channel impedance analyzer is smaller in size than the fiber optic demodulator, and it is easy to carry. It can realize the large-area detection of pile foundation bearing capacity. .

附图说明Description of drawings

图1为本发明实施例1提供的分布式压电电缆阻抗传感技术检测桩基承载力原理图;Fig. 1 is the schematic diagram of detecting pile foundation bearing capacity by the distributed piezoelectric cable impedance sensing technology provided by Embodiment 1 of the present invention;

图2为图1中的多通道阻抗分析仪的结构示意图;Fig. 2 is the structural representation of the multi-channel impedance analyzer in Fig. 1;

图3为图1中的分布式压电电缆的结构示意图;Fig. 3 is a schematic structural diagram of the distributed piezoelectric cable in Fig. 1;

图4为本发明实施例1提供的PHC管桩内的分布式压电电缆的布置示意图;4 is a schematic diagram of the layout of the distributed piezoelectric cables in the PHC pipe pile provided by Embodiment 1 of the present invention;

图5为图4的截面图Figure 5 is a cross-sectional view of Figure 4

图6为本发明实施例2提供的钻孔灌注桩内的分布式压电电缆布置示意图;6 is a schematic diagram of the arrangement of distributed piezoelectric cables in the bored pile provided by Embodiment 2 of the present invention;

图7为图6的截面图。FIG. 7 is a cross-sectional view of FIG. 6 .

附图标记:Reference signs:

1-桩体、2-分布式压电电缆、3-多通道阻抗分析仪、4-压电电缆导线、5-压电电缆、6-开关交换装置、7-多通道阻抗分析仪开关、8-多通道阻抗分析仪检测深度旋钮、9-多通道阻抗分析仪阻抗采集按键、10-多通道阻抗分析仪接线孔、11-热缩管;12、布线槽。1-Pile, 2-Distributed piezoelectric cable, 3-Multi-channel impedance analyzer, 4-Piezoelectric cable conductor, 5-Piezoelectric cable, 6-Switch switching device, 7-Multi-channel impedance analyzer switch, 8 -Multi-channel impedance analyzer detection depth knob, 9-Multi-channel impedance analyzer impedance acquisition button, 10-Multi-channel impedance analyzer wiring hole, 11-Heat shrink tube; 12, Wiring groove.

具体实施方式Detailed ways

下面将结合本发明实施例中的附图,对本发明实施例中的技术方案进行清楚、完整地描述,显然,所描述的实施例仅仅是本发明一部分实施例,而不是全部的实施例。基于本发明中的实施例,本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例,都属于本发明保护的范围。The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

请参阅图1~5,本发明实施例1提供的一种利用分布式压电电缆阻抗传感技术检测桩基承载力的系统,包括多通道阻抗分析仪3和分布式压电电缆2,分布式压电电缆2沿桩体长度方向分布且内置于桩体1内,分布式压电电缆2环绕桩体1均匀分布至少三条,本实施例中分布4条,分布式压电电缆2与多通道阻抗分析仪3电信号连接,分布式压电电缆2包括压电电缆5、压电电缆导线4和开关交换装置6,其中压电电缆5和压电电缆导线4平行分布,压电电缆导线4与压电电缆5之间多处设置开关交换装置6,通过所述开关交换装置6控制多通道阻抗分析仪3所要检测的位置,所述的分布式压电电缆2整体采用外皮包裹约束。Please refer to Figures 1 to 5, a system for detecting the bearing capacity of pile foundations using distributed piezoelectric cable impedance sensing technology provided in Embodiment 1 of the present invention, including a multi-channel impedance analyzer 3 and distributed piezoelectric cables 2, distributed Piezoelectric cables 2 are distributed along the length of the pile body and built into the pile body 1. At least three distributed piezoelectric cables 2 are evenly distributed around the pile body 1. In this embodiment, 4 are distributed. The distributed piezoelectric cables 2 and multiple The channel impedance analyzer 3 is connected to the electrical signal, and the distributed piezoelectric cable 2 includes a piezoelectric cable 5, a piezoelectric cable conductor 4 and a switching device 6, wherein the piezoelectric cable 5 and the piezoelectric cable conductor 4 are distributed in parallel, and the piezoelectric cable conductor 4 and the piezoelectric cable 5 are provided with switching devices 6 at multiple places, through which the position to be detected by the multi-channel impedance analyzer 3 is controlled. The distributed piezoelectric cable 2 as a whole is restrained by wrapping.

参照图3-5所示,所述分布式压电电缆2采用热缩管11对分布式压电电缆2进行封装,可有效保护电缆。所述桩体1为PHC管桩,PHC管桩表面沿桩身表面预先设计所要测试的路线开设有布线槽12,所述分布式压电电缆2置入在布线槽12内并采用胶凝材料固化封装,每个测试截面间隔90°布设四组所述分布式压电电缆2,上述构造方便阻抗分布式压电电缆2以同步变化的方式检测桩身的轴力变化。Referring to Figures 3-5, the distributed piezoelectric cable 2 is packaged with a heat-shrinkable tube 11, which can effectively protect the cable. The pile body 1 is a PHC pipe pile, and the surface of the PHC pipe pile is provided with a wiring groove 12 along the pre-designed route to be tested on the surface of the pile body. The distributed piezoelectric cable 2 is placed in the wiring groove 12 and is made of a gel material For curing and encapsulation, four groups of the distributed piezoelectric cables 2 are arranged at intervals of 90° in each test section. The above structure facilitates the impedance distributed piezoelectric cables 2 to detect the change of the axial force of the pile body in a synchronous manner.

参照图1-4所示,本发明还提供上述利用分布式压电电缆阻抗传感技术检测桩基承载力的系统的施工方法,包括以下步骤:Referring to Figures 1-4, the present invention also provides a construction method for the above-mentioned system for detecting the bearing capacity of pile foundations using distributed piezoelectric cable impedance sensing technology, including the following steps:

(1)开槽布线:沿桩身表面预先设计所要测试的路线,后用切割工具沿设计路线进行开槽,其深度和宽度以能放入分布式压电电缆2为准,每个检测截面环绕间隔90°布设四组所述分布式压电电缆2,在分布式压电电缆2埋入后采取定点固定;(1) Slotted wiring: pre-design the route to be tested along the surface of the pile body, and then use a cutting tool to slot along the designed route. The depth and width shall be subject to the distributed piezoelectric cable 2. Arrange four groups of the distributed piezoelectric cables 2 at intervals of 90°, and fix them at fixed points after the distributed piezoelectric cables 2 are embedded;

(2)涂胶防护:布线槽12使用环氧树脂进行填充、粘贴和表面保护;(2) Glue protection: the wiring slot 12 is filled, pasted and surface protected with epoxy resin;

(3)数据采集线路连接:压电电缆导线4的端头与多通道阻抗分析仪3连接组成分布式压电电缆2阻抗传感技术检测PHC管桩桩基承载力的系统进行数据采集。(3) Data acquisition line connection: the end of the piezoelectric cable conductor 4 is connected to the multi-channel impedance analyzer 3 to form a system for detecting the bearing capacity of the PHC pipe pile foundation with distributed piezoelectric cable 2 impedance sensing technology for data acquisition.

上述利用分布式压电电缆阻抗传感技术检测桩基承载力的系统的检测方法,包括,在桩基承载力的作用下,桩身产生应力和应变,以使所述分布式压电电缆2的阻抗发生变化,利用阻抗变化的输出信号判定灌注桩或PHC管桩的轴力变化,从而推算出灌注桩或PHC管桩的侧摩阻力和桩端承载力的变化,包括:The detection method of the system for detecting the bearing capacity of the pile foundation using the distributed piezoelectric cable impedance sensing technology includes, under the action of the bearing capacity of the pile foundation, stress and strain are generated on the pile body, so that the distributed piezoelectric cable 2 The impedance of the cast-in-situ pile changes, and the output signal of the impedance change is used to determine the axial force change of the cast-in-place pile or PHC pipe pile, so as to calculate the side friction resistance and the change of the pile end bearing capacity of the cast-in-place pile or PHC pipe pile, including:

(1)通过多通道阻抗分析仪3测试得到压电电缆5的轴向阻抗Z(h),由于阻抗的变化与应变成线性关系,从而推算出压电电缆5的轴向应变ε(h),由于压电电缆5固定在桩身表面,在静载力下,压电电缆5轴向变形与桩身轴向一致,因此桩身应变也为应变ε(h),则桩身应力σ(h)为:(1) The axial impedance Z(h) of the piezoelectric cable 5 is obtained through the test of the multi-channel impedance analyzer 3. Since the change of the impedance has a linear relationship with the strain, the axial strain ε(h) of the piezoelectric cable 5 is calculated ), since the piezoelectric cable 5 is fixed on the surface of the pile body, under the static load, the axial deformation of the piezoelectric cable 5 is consistent with the axial direction of the pile body, so the strain of the pile body is also the strain ε(h), and the stress of the pile body σ (h) is:

σ(h)=ε(h)·Ec,其中,Ec为桩体1的弹性模量;σ(h)=ε(h)·E c , where E c is the modulus of elasticity of the pile body 1;

根据桩身应力σ(Z),桩身轴力Q(h)为:According to the pile body stress σ(Z), the pile body axial force Q(h) is:

Q(h)=σ(h)·A,其中A为桩身截面面积。Q(h)=σ(h)·A, where A is the cross-sectional area of the pile body.

(2)通过测试植入桩体内部压电电缆5的阻抗变化,即可获得沿桩身不同荷载变形下分布式压电电缆的应变值,设ε1(h)和ε2(h)分别为测试得到的桩体1在深度h处的沿水平荷载方向上对称部位的应变测试值,桩身应变一侧受拉一侧受压,则轴向压缩应变εa(h)和弯曲应变值εm(h)分别为:(2) By testing the impedance change of the piezoelectric cable 5 implanted in the pile body, the strain value of the distributed piezoelectric cable under different load deformations along the pile body can be obtained. Let ε 1 (h) and ε 2 (h) be respectively In order to obtain the strain test value of pile body 1 at the depth h at the symmetrical position along the horizontal load direction, one side of the pile body is under tension and the other side is under compression, then the axial compressive strain ε a (h) and the value of bending strain ε m (h) are respectively:

Figure BDA0003485065630000071
Figure BDA0003485065630000071

上述多通道阻抗分析仪3集发射和接收信号为一体,其测得的数值为频率为1kHz、电压为1V下多根压电电缆的阻抗变化;所述的多通道阻抗分析仪3,具有控制开关检测交换装置6的功能,能够实现开关命令发射。The above-mentioned multi-channel impedance analyzer 3 integrates transmitting and receiving signals, and the measured value is the impedance change of multiple piezoelectric cables under a frequency of 1kHz and a voltage of 1V; the multi-channel impedance analyzer 3 has a control The switch detects the function of the switching device 6 and can realize the transmission of switch commands.

参照图1、图2、图3、图6、图7所示,本发明实施例2与实施例1基本相同,其区别仅在于:所述桩体1为灌注桩,灌注桩钢筋笼上沿截面间隔90°均匀分布的4根纵筋上通过扎丝和环氧树脂各固定一根分布式压电电缆2。With reference to Fig. 1, Fig. 2, Fig. 3, Fig. 6, shown in Fig. 7, embodiment 2 of the present invention is basically the same as embodiment 1, and its difference is only: described pile body 1 is cast-in-place pile, and the upper edge of cast-in-situ pile reinforcement cage A distributed piezoelectric cable 2 is respectively fixed on the four longitudinal ribs evenly distributed at 90° cross-sectional intervals by wire binding and epoxy resin.

其施工步骤包括:Its construction steps include:

(1)埋设电缆:在灌注桩钢筋笼上沿截面间隔90°均匀分布的4根纵筋上通过扎丝和环氧树脂各固定一根分布式压电电缆2;(1) Embed cables: fix a distributed piezoelectric cable 2 on the cast-in-place pile reinforcement cage and fix a distributed piezoelectric cable 2 on the 4 longitudinal reinforcements evenly distributed along the cross-sectional interval of 90° by binding wire and epoxy resin;

(2)浇筑桩体:将绑扎有分布式压电电缆的灌注桩钢筋笼吊装入桩孔中,再灌注混凝土,使混凝土包裹住分布式压电电缆2;(2) Pouring the pile body: hoist the cast-in-situ pile reinforcement cage bound with the distributed piezoelectric cable into the pile hole, and then pour concrete so that the concrete wraps the distributed piezoelectric cable 2;

(3)数据采集线路连接:压电电缆导线4的端头与多通道阻抗分析仪3连接组成分布式压电电缆2阻抗传感技术检测灌注桩桩基承载力的系统进行数据采集。(3) Data acquisition line connection: the end of the piezoelectric cable conductor 4 is connected to the multi-channel impedance analyzer 3 to form a system for detecting the bearing capacity of the cast-in-place pile foundation with the distributed piezoelectric cable 2 impedance sensing technology for data acquisition.

以上所述,仅为本发明较佳的具体实施方式,但本发明的保护范围并不局限于此,任何熟悉本技术领域的技术人员在本发明揭露的技术范围内,根据本发明的技术方案及其发明构思加以等同替换或改变,都应涵盖在本发明的保护范围之内。The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto, any person familiar with the technical field within the technical scope disclosed in the present invention, according to the technical solution of the present invention Any equivalent replacement or change of the inventive concepts thereof shall fall within the protection scope of the present invention.

Claims (8)

1. A system for detecting pile foundation bearing capacity by using distributed piezoelectric cable impedance sensing technology is characterized in that: including multichannel impedance analyzer and distributed piezoelectric cable, distributed piezoelectric cable distributes along pile length direction and embeds in the pile body, distributed piezoelectric cable encircles pile body evenly distributed at least three, distributed piezoelectric cable and multichannel impedance analyzer electrical signal connection, distributed piezoelectric cable includes piezoelectric cable, piezoelectric cable wire and switch exchange device, wherein piezoelectric cable and piezoelectric cable wire parallel distribution, a plurality of departments set up switch exchange device between piezoelectric cable wire and the piezoelectric cable, through switch exchange device control multichannel impedance analyzer's position that will detect, distributed piezoelectric cable wholly adopt the crust parcel constraint.
2. The system for detecting pile foundation bearing capacity by using distributed piezoelectric cable impedance sensing technology according to claim 1, wherein: the pile body is a PHC pipe pile, a wiring groove is formed in the surface of the PHC pipe pile along a route to be tested, the distributed piezoelectric cables are placed in the wiring groove and are solidified and packaged by adopting cementing materials, and four groups of distributed piezoelectric cables are distributed at intervals of 90 degrees in each test section.
3. The system for detecting pile foundation bearing capacity by using distributed piezoelectric cable impedance sensing technology according to claim 1, wherein: the pile body is a filling pile, and 4 longitudinal ribs which are uniformly distributed on the filling pile reinforcement cage along the section at intervals of 90 degrees are respectively fixed with a distributed piezoelectric cable through binding wires and epoxy resin.
4. A method of constructing a system for detecting pile foundation bearing capacity using distributed piezoelectric cable impedance sensing technology as claimed in claim 1, wherein: the method comprises the following steps:
(1) Burying a cable: the distributed piezoelectric cables are embedded into the pile body in a surrounding mode, four groups of distributed piezoelectric cables are distributed at 90-degree surrounding intervals of each detection section, and fixed points are adopted for fixation after the distributed piezoelectric cables are embedded;
(2) And (3) connecting a data acquisition line: the end heads of the piezoelectric cable wires are connected with a multichannel impedance analyzer to form a system for detecting pile foundation bearing capacity of the pile body by using the distributed piezoelectric cable impedance sensing technology for data acquisition.
5. The construction method of the system for detecting pile foundation bearing capacity by using the distributed piezoelectric cable impedance sensing technology according to claim 4, wherein the construction method comprises the following steps: the pile body is PHC pipe pile, and the construction steps comprise:
(1) Grooving wiring: a route to be tested is designed in advance along the surface of the pile body, then a cutting tool is used for grooving along the designed route, the depth and the width of the groove are based on the fact that distributed piezoelectric cables can be placed in the groove, four groups of distributed piezoelectric cables are distributed around each detection section at 90-degree intervals, and fixed points are adopted for fixation after the distributed piezoelectric cables are buried;
(2) Gluing protection: the wiring groove is filled, adhered and surface-protected by epoxy resin;
(3) And (3) connecting a data acquisition line: the end heads of the piezoelectric cable wires are connected with a multichannel impedance analyzer to form a distributed piezoelectric cable impedance sensing technology system for detecting the pile foundation bearing capacity of the PHC pipe pile for data acquisition.
6. The construction method of the system for detecting pile foundation bearing capacity by using the distributed piezoelectric cable impedance sensing technology according to claim 4, wherein the construction method comprises the following steps: the pile body is a filling pile, and the construction steps comprise:
(1) Burying a cable: 4 longitudinal ribs uniformly distributed on the cast-in-place pile reinforcement cage at intervals of 90 degrees along the section are respectively fixed with a distributed piezoelectric cable through binding wires and epoxy resin;
(2) Pouring the pile body: hoisting a bored concrete pile reinforcement cage bound with the distributed piezoelectric cable into the pile hole, and then pouring concrete to enable the concrete to wrap the distributed piezoelectric cable;
(3) And (3) connecting a data acquisition line: the end heads of the piezoelectric cable wires are connected with a multichannel impedance analyzer to form a distributed piezoelectric cable impedance sensing technology system for detecting the bearing capacity of the pile foundation of the cast-in-place pile for data acquisition.
7. A method of detecting a system for detecting pile foundation bearing capacity using distributed piezoelectric cable impedance sensing technology as claimed in claim 1, wherein: under the effect of pile foundation bearing force, pile body produces stress and strain, so that the impedance of piezoelectricity cable sensor changes, utilizes the output signal of impedance change to judge the axial force change of bored concrete pile or PHC tubular pile to calculate the change of the side friction resistance and pile tip bearing force of bored concrete pile or PHC tubular pile, include:
(1) The axial impedance Z (h) of the piezoelectric cable is obtained through the test of the multichannel impedance analyzer, the axial strain epsilon (h) of the piezoelectric cable is calculated because the change of the impedance and the strain form a linear relation, the piezoelectric cable is fixed on the surface of the pile body, the axial deformation of the piezoelectric cable is consistent with the axial direction of the pile body under static load force, the strain epsilon (h) of the pile body is also obtained, and the stress sigma (h) of the pile body is as follows:
σ(h)=ε(h)·E c wherein E is c Is the elastic modulus of the pile body.
According to pile body stress sigma (Z), pile body axial force Q (h) is:
q (h) =σ (h) ·a, where a is the shaft cross-sectional area,
(2) The strain value of the distributed piezoelectric cable under different load deformations along the pile body can be obtained by testing the impedance change of the piezoelectric cable implanted into the pile body, and epsilon is set 1 (h) And epsilon 2 (h) Respectively testing the strain test values of the symmetrical parts of the pile body at the depth h along the horizontal load direction, and axially compressing the strain epsilon when one side of the pile body is pulled and the other side is pressed a (h) And bending strain value epsilon m (h) The method comprises the following steps of:
Figure QLYQS_1
8. the method for detecting the pile foundation bearing capacity by using the distributed piezoelectric cable impedance sensing technology according to claim 7, wherein the method comprises the following steps: the multichannel impedance analyzer integrates transmitting and receiving signals, and the measured value is the impedance change of a plurality of piezoelectric cables under the conditions of 1kHz and 1V voltage; the multichannel impedance analyzer has the function of controlling the switch detection switching device, and can realize switch command emission.
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Application publication date: 20220506

Assignee: Yueqing Transportation and Water Conservancy Investment Group Co.,Ltd.

Assignor: Wenzhou University

Contract record no.: X2024330001356

Denomination of invention: System and construction and testing method for detecting the bearing capacity of pile foundation using distributed piezoelectric cable impedance sensing technology

Granted publication date: 20230707

License type: Common License

Record date: 20241208