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CN110954407B - Method for testing concrete fracture process under different hydraulic pressure effects - Google Patents

Method for testing concrete fracture process under different hydraulic pressure effects Download PDF

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CN110954407B
CN110954407B CN201811120558.8A CN201811120558A CN110954407B CN 110954407 B CN110954407 B CN 110954407B CN 201811120558 A CN201811120558 A CN 201811120558A CN 110954407 B CN110954407 B CN 110954407B
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crack
test beam
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concrete
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胡少伟
王洋
乔艳敏
黄逸群
喻江
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Nanjing Hydraulic Research Institute of National Energy Administration Ministry of Transport Ministry of Water Resources
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
    • G01N3/10—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces generated by pneumatic or hydraulic pressure
    • G01N3/12—Pressure testing
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/02—Details
    • G01N3/04—Chucks
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/02—Details
    • G01N3/06—Special adaptations of indicating or recording means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/02—Details
    • G01N3/06—Special adaptations of indicating or recording means
    • G01N3/066—Special adaptations of indicating or recording means with electrical indicating or recording means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/20—Investigating strength properties of solid materials by application of mechanical stress by applying steady bending forces
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0014—Type of force applied
    • G01N2203/0026—Combination of several types of applied forces
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0058—Kind of property studied
    • G01N2203/006—Crack, flaws, fracture or rupture
    • G01N2203/0062—Crack or flaws
    • G01N2203/0064—Initiation of crack
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/04—Chucks, fixtures, jaws, holders or anvils
    • G01N2203/0423—Chucks, fixtures, jaws, holders or anvils using screws
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/06—Indicating or recording means; Sensing means
    • G01N2203/0617—Electrical or magnetic indicating, recording or sensing means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/06—Indicating or recording means; Sensing means
    • G01N2203/0658—Indicating or recording means; Sensing means using acoustic or ultrasonic detectors

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Abstract

The invention relates to a method for testing a concrete fracture process under different hydraulic pressure effects, and belongs to the technical field of physical measurement. The method comprises the following steps: 1) Wrapping a crack sealing adhesive tape at a crack prefabricated by the test beam, clamping the crack sealing adhesive tape by using a clamp, wherein a pressure measuring hole is arranged in a fracture process area of the test beam, and water pressure measuring devices are arranged at two ends of the pressure measuring hole; 2) The midpoint of the top surface of the crack sealing adhesive tape is used as a force application point, and a load is applied to the test beam by pre-applying water pressureFThe maximum load to be applied is measured by a load measuring deviceF max Crack initiation load is measured by a strain measurement deviceF ini The method comprises the steps of carrying out a first treatment on the surface of the 3) Opening displacement measuring brackets are respectively arranged at the bottom end and the tip end of the prefabricated crack, a clamp type extensometer is arranged on the displacement measuring brackets, and an acoustic emission detector is arranged on the test beam; 4) Calculating fracture toughness
Figure DEST_PATH_FDA0001873841400000011
And instability toughness
Figure DEST_PATH_FDA0001873841400000012
. The method meets the requirement that the concrete test beam fracture performance parameters are accurately tested by the three-point bending beam test under the coupling effect of the water pressure and the load in the crack.

Description

一种不同水压作用下混凝土断裂过程测试方法A method for testing the fracture process of concrete under different water pressures

技术领域Technical Field

本发明涉及一种不同水压作用下混凝土断裂过程测试方法，属于物理测量技术领域。The invention relates to a method for testing a concrete fracture process under different water pressures, and belongs to the technical field of physical measurement.

背景技术Background Art

三点弯曲梁测试法是目前研究混凝土断裂性能的主要方法之一，测试实验中仅需要测量三点弯曲梁的裂缝口张开位移、外加荷载即可计算得到混凝土的断裂参数（主要包括起裂韧度、失稳韧度、断裂能等参数），实验过程操作简易，试验结果的认可度高。该方法已作为混凝土断裂性能测试的主要方法被列入我国水利行业规程DL/T5332-2005《水工混凝土断裂试验规程》。The three-point bending beam test method is one of the main methods for studying the fracture performance of concrete. In the test experiment, only the crack opening displacement of the three-point bending beam and the applied load need to be measured to calculate the fracture parameters of the concrete (mainly including crack initiation toughness, instability toughness, fracture energy and other parameters). The experimental process is simple to operate and the test results are highly recognized. This method has been included in the Chinese water conservancy industry regulations DL/T5332-2005 "Hydraulic Concrete Fracture Test Regulations" as the main method for concrete fracture performance testing.

但是，现有规程DL/T5332-2005《水工混凝土断裂试验规程》中提出的三点弯曲梁测试法并不能对水工结构工程中混凝土受到裂缝内水压力与荷载耦合作用下的断裂性能进行测试。具体如下：However, the three-point bending beam test method proposed in the existing specification DL/T5332-2005 "Hydraulic Concrete Fracture Test Specification" cannot test the fracture performance of concrete in hydraulic structure engineering under the coupling effect of water pressure in cracks and load. The details are as follows:

1. 水工建筑工程中的混凝土裂缝经常会处于水压环境中，裂缝受水压的劈裂作用，其断裂性能也势必会受到影响。《水工混凝土断裂试验规程》中规定的三点弯曲梁测试法只是在实验室条件下或者受外部因素影响后的混凝土梁的断裂性能，其测试结果不能反映水压与荷载共同耦合作用下的混凝土断裂性能。1. Concrete cracks in hydraulic construction projects are often in a water pressure environment. The cracks are split by water pressure, and their fracture performance is bound to be affected. The three-point bending beam test method specified in the "Hydraulic Concrete Fracture Test Procedure" is only the fracture performance of concrete beams under laboratory conditions or after being affected by external factors. Its test results cannot reflect the concrete fracture performance under the combined coupling of water pressure and load.

2. 水工混凝土结构在服役中长期处于水压环境下，判定水工混凝土结构中水压对其混凝土断裂性能的影响规律，以及水压在结构承载力失效中所起的力学作用，对预测水压环境下混凝土结构的寿命具有指导意义。2. Hydraulic concrete structures are in a water pressure environment for a long time during their service. Determining the influence of water pressure on the fracture performance of concrete in hydraulic concrete structures and the mechanical role of water pressure in the failure of structural bearing capacity is of guiding significance for predicting the life of concrete structures under water pressure environment.

3. 水压环境下水工结构裂缝表面一直处于水压力的作用之下，结构承载过程中裂缝的扩展会影响缝内水压分布，相应的缝内水压分布的改变会影响水压力对结构的荷载作用。《水工混凝土断裂试验规程》中规定的三点弯曲梁测试法难以对该种耦合作用下的混凝土断裂过程进行测试。3. The crack surface of the hydraulic structure is always under the action of water pressure under the water pressure environment. The expansion of the crack during the structural load-bearing process will affect the water pressure distribution in the crack. The corresponding change in the water pressure distribution in the crack will affect the load effect of water pressure on the structure. The three-point bending beam test method specified in the "Hydraulic Concrete Fracture Test Code" is difficult to test the concrete fracture process under this coupling effect.

4. 水工建筑结构的混凝土出现裂缝的频率很高，水工混凝土结构特别是深水混凝土结构长期受到外部荷载及裂缝内的水压力共同的作用。《水工混凝土断裂试验规程》中并没有提供水压与荷载耦合作用下混凝土断裂试验装置。4. The frequency of cracks in the concrete of hydraulic structures is very high. Hydraulic concrete structures, especially deep-water concrete structures, are subjected to the combined effects of external loads and water pressure in the cracks for a long time. The "Hydraulic Concrete Fracture Test Procedure" does not provide a concrete fracture test device under the coupling of water pressure and load.

综上所述，对裂缝内水压与荷载耦合作用下混凝土试验梁断裂性能参数进行准确的测试与计算具有重要的意义及工程应用价值。In summary, accurate testing and calculation of the fracture performance parameters of concrete test beams under the coupling of water pressure and load in cracks has important significance and engineering application value.

发明内容Summary of the invention

针对上述现有技术存在的不足，本发明主要解决的技术问题是：提出一种对裂缝内水压与荷载耦合作用下混凝土试验梁断裂性能参数进行准确的测试方法。In view of the above-mentioned deficiencies in the prior art, the main technical problem solved by the present invention is to propose a method for accurately testing the fracture performance parameters of a concrete test beam under the coupling effect of water pressure in a crack and load.

本发明为解决上述技术问题提出的技术方案是：一种不同水压作用下混凝土断裂过程测试方法，包括以下步骤：The technical solution proposed by the present invention to solve the above technical problems is: a method for testing the fracture process of concrete under different water pressures, comprising the following steps:

1）在试验梁预制的裂缝处裹贴上裂缝密封胶带，使用夹具夹紧所述裂缝密封胶带，所述试验梁的断裂过程区设有测压孔，所述测压孔两端设有水压测量装置；1) Wrap crack sealing tape on the prefabricated crack of the test beam, and clamp the crack sealing tape with a clamp. A pressure measuring hole is provided in the fracture process area of the test beam, and water pressure measuring devices are provided at both ends of the pressure measuring hole;

2）在所述裂缝密封胶带顶面中点为施力点，通过预加水压向所述所述试验梁施加荷载F，通过荷载测量装置测出需要施加的最大荷载F max ，通过应变测量装置测出起裂荷载F ini ；2) Taking the midpoint of the top surface of the crack sealing tape as the force application point, applying a load F to the test beam by pre-adding water pressure, measuring the maximum load F max to be applied by a load measuring device, and measuring the crack initiation load Fini by a strain measuring device;

3）在预制裂缝的底端和尖端分别安装张口位移测量支架，在所述位移测量支架上安装位移测量装置，在所述试验梁上安装有声发射检测仪；3) An opening displacement measuring bracket is installed at the bottom and tip of the prefabricated crack respectively, a displacement measuring device is installed on the displacement measuring bracket, and an acoustic emission detector is installed on the test beam;

4）按照下式计算起裂韧度

Figure SMS_1
和失稳韧度
Figure SMS_2
4) Calculate the crack initiation toughness according to the following formula:
Figure SMS_1
and buckling toughness
Figure SMS_2

起裂韧度

Figure SMS_3
的计算：Crack initiation toughness
Figure SMS_3
Calculation:

Figure SMS_4
Figure SMS_4

其中：in:

Figure SMS_5
Figure SMS_5

式中：

Figure SMS_6
为起裂韧度，单位为MPa·m1/2；Fini为起裂荷载，单位为kN；α0＝a0/h，a0为初始裂缝长度；S为试验梁两支座间的跨度，单位m；t为试验梁厚度，单位m；h为试验梁高度，单位m；m为试验梁支座间的质量，用试验梁的总质量按S/L比折算，单位kg；L为试验梁长度，单位m；g为重力加速度，为9.8m/s2，Where:
Figure SMS_6
is the crack initiation toughness, in MPa·m 1/2 ; Fini is the crack initiation load, in kN; α 0 =a 0 /h, a 0 is the initial crack length; S is the span between the two supports of the test beam, in m; t is the thickness of the test beam, in m; h is the height of the test beam, in m; m is the mass between the supports of the test beam, converted by the total mass of the test beam according to the S/L ratio, in kg; L is the length of the test beam, in m; g is the acceleration of gravity, which is 9.8m/s 2 ,

失稳韧度

Figure SMS_7
的计算：Instability toughness
Figure SMS_7
Calculation:

Figure SMS_8
Figure SMS_8

其中：in:

Figure SMS_9
Figure SMS_9

其中，α＝ac/h，ac为临界裂缝长度，单位mm，应按下式计算：Where, α = a c /h, a c is the critical crack length, unit is mm, and should be calculated as follows:

Figure SMS_10
Figure SMS_10

式中：F max为最大荷载，单位kN；E为试验梁的计算弹性模量，单位GPa；h 0 为夹式引伸计与裂缝之间的距离高度，单位mm；V c 为裂缝张开位移临界值。Where: F max is the maximum load, unit is kN; E is the calculated elastic modulus of the test beam, unit is GPa; h 0 is the distance height between the clip-on extensometer and the crack, unit is mm; V c is the critical value of crack opening displacement.

本发明采用上述技术方案的有益效果在于：测试混凝土试验梁在裂缝内水压及外荷载共同耦合作用下的断裂特性，将裂缝密封装置安置在试验梁中心，通过通水管道向裂缝内部加水压，通过试验梁断裂过程区测压孔检测断裂过程中裂缝内水压变化规律，通过位移、荷载测量装置测量断裂过程中裂缝张口位移及荷载变化规律，通过声发射仪检测混凝土试验梁的起裂。The beneficial effects of the technical scheme adopted in the present invention are: testing the fracture characteristics of a concrete test beam under the combined coupling of water pressure in a crack and an external load, placing a crack sealing device at the center of the test beam, applying water pressure to the inside of the crack through a water pipe, detecting the variation law of water pressure in the crack during the fracture process through a pressure measuring hole in the fracture process zone of the test beam, measuring the crack opening displacement and load variation law during the fracture process through a displacement and load measuring device, and detecting the initiation of cracking of the concrete test beam through an acoustic emission instrument.

本发明提供的混凝土试验梁裂缝内水压加载装置，保证了裂缝内部全水压加载的状态，外加荷载的加载方式与一般的三点弯曲梁法一致。水压与荷载耦合作用下混凝土三点弯曲梁断裂试验，其加载装置更加贴切的模拟了水工混凝土实际过程中裂缝受水压力的状态，测试方法按照三点弯曲梁法进行，得出的断裂参数计算公式进一步的发展混凝土断裂性能测试试验，补充了行业规程DL/T5332-2005《水工混凝土断裂试验规程》。The water pressure loading device for the crack of the concrete test beam provided by the present invention ensures that the crack is fully loaded with water pressure, and the loading method of the external load is consistent with the general three-point bending beam method. The concrete three-point bending beam fracture test under the coupling of water pressure and load, its loading device more closely simulates the state of water pressure on the crack in the actual process of hydraulic concrete, the test method is carried out according to the three-point bending beam method, and the fracture parameter calculation formula obtained further develops the concrete fracture performance test, supplementing the industry specification DL/T5332-2005 "Hydraulic Concrete Fracture Test Specification".

上述方案的进一步改进是：预制裂缝的两侧预埋有通水管道，所述通水管道为金属波纹弯管。A further improvement of the above scheme is that water pipes are pre-buried on both sides of the prefabricated cracks, and the water pipes are metal corrugated elbows.

上述方案的进一步改进是：所述裂缝密封胶带为丁基橡胶胶带，所述夹具为钢制夹具并通过螺栓夹紧。A further improvement of the above solution is that the crack sealing tape is a butyl rubber tape, and the clamp is a steel clamp and is clamped by bolts.

上述方案的进一步改进是：所述测压孔通过使用钢棒在试验梁内部预制通孔，所述测压孔两端设有螺纹接头。A further improvement of the above solution is that: the pressure measuring hole is prefabricated as a through hole inside the test beam by using a steel rod, and threaded joints are provided at both ends of the pressure measuring hole.

上述方案的进一步改进是：所述张口位移测量支架包括L形的钢支座和端部缺口的钢棒并通过螺栓连接固定。A further improvement of the above scheme is that the opening displacement measuring bracket includes an L-shaped steel support and a steel rod with a notch at the end and they are fixed by bolt connection.

上述方案的进一步改进是：所述水压采集装置为压力变换器。A further improvement of the above solution is that the water pressure collection device is a pressure converter.

上述方案的进一步改进是：所述的声发射采集装置为粘贴在所述试验梁表面的高频声发射传感器。A further improvement of the above scheme is that the acoustic emission collection device is a high-frequency acoustic emission sensor pasted on the surface of the test beam.

上述方案的进一步改进是：所述荷载量测装置是荷载传感器，所述应变测量装置是粘贴在预制裂缝尖端两侧的电阻应变片。A further improvement of the above scheme is that: the load measuring device is a load sensor, and the strain measuring device is a resistance strain gauge pasted on both sides of the prefabricated crack tip.

附图说明BRIEF DESCRIPTION OF THE DRAWINGS

图1是本发明结构示意图。FIG1 is a schematic diagram of the structure of the present invention.

图2是试验梁剖视示意图。FIG2 is a schematic cross-sectional view of the test beam.

图中示例：荷载测量装置1、夹具2、螺纹接头3、水压采集装置4、裂缝张口位移测量支架5、进水管道6、夹式引伸计7、出水管道8、支撑座9、声发射检测仪10、试验梁11、裂缝密封胶带12、施力座13、通水管道口14、测压孔15、裂缝16。Example in the figure: load measuring device 1, fixture 2, threaded joint 3, water pressure collection device 4, crack opening displacement measurement bracket 5, water inlet pipe 6, clamp-type extensometer 7, water outlet pipe 8, support seat 9, acoustic emission detector 10, test beam 11, crack sealing tape 12, force seat 13, water pipe opening 14, pressure measuring hole 15, crack 16.

具体实施方式DETAILED DESCRIPTION

实施例Example

本实施例的不同水压作用下混凝土断裂过程测试方法，如图1至图2所示，包括以下步骤：The concrete fracture process testing method under different water pressures of this embodiment, as shown in FIGS. 1 and 2 , includes the following steps:

1）试验梁11整体放置在支撑座上9，在试验梁11预制的裂缝16处裹贴上裂缝密封胶带12，使用夹具2夹紧裂缝密封胶带12，试验梁11的断裂过程区设有测压孔15，测压孔15两端设有水压测量装置；1) The test beam 11 is placed as a whole on the support seat 9, the crack sealing tape 12 is wrapped and pasted on the prefabricated crack 16 of the test beam 11, and the crack sealing tape 12 is clamped by the clamp 2. The fracture process area of the test beam 11 is provided with a pressure measuring hole 15, and water pressure measuring devices are provided at both ends of the pressure measuring hole 15;

2）在裂缝密封胶带12顶面中点为施力点，通过预加水压向试验梁11上的施力座13施加荷载F，通过荷载测量装置1测出需要施加的最大荷载Fmax，通过声发射仪测出起裂荷载Fini；2) With the midpoint of the top surface of the crack sealing tape 12 as the force application point, a load F is applied to the force application seat 13 on the test beam 11 by pre-adding water pressure, the maximum load F max to be applied is measured by the load measuring device 1, and the crack initiation load Fini is measured by the acoustic emission instrument;

3）在预制裂缝16的底端和尖端分别安装裂缝张口位移测量支架5，在裂缝张口位移测量支架5上安装位移测量装置，在试验梁11上安装有声发射检测仪10；3) A crack opening displacement measuring bracket 5 is installed at the bottom and tip of the prefabricated crack 16, a displacement measuring device is installed on the crack opening displacement measuring bracket 5, and an acoustic emission detector 10 is installed on the test beam 11;

4）按照下式计算起裂韧度

Figure SMS_11
和失稳韧度
Figure SMS_12
4) Calculate the crack initiation toughness according to the following formula:
Figure SMS_11
and buckling toughness
Figure SMS_12

起裂韧度

Figure SMS_13
的计算：Crack initiation toughness
Figure SMS_13
Calculation:

Figure SMS_14
Figure SMS_14

其中：in:

Figure SMS_15
Figure SMS_15

式中：

Figure SMS_16
为起裂韧度，单位为MPa·m1/2；Fini为起裂荷载，单位为kN；α0＝a0/h，a 0为初始裂缝16长度；S为试验梁11两支座间的跨度，单位m；t为试验梁11厚度，单位m；h为试验梁11高度，单位m；m为试验梁11支座间的质量，用试验梁11的总质量按S/L比折算，单位kg；L为试验梁11长度，单位m；g为重力加速度，为9.8 m/s2。Where:
Figure SMS_16
is the crack initiation toughness, in MPa·m 1/2 ; Fini is the crack initiation load, in kN; α 0 =a 0 /h, a 0 is the length of the initial crack 16; S is the span between the two supports of the test beam 11, in m; t is the thickness of the test beam 11, in m; h is the height of the test beam 11, in m; m is the mass between the supports of the test beam 11, converted by the total mass of the test beam 11 according to the S/L ratio, in kg; L is the length of the test beam 11, in m; g is the acceleration of gravity, which is 9.8 m/s 2 .

失稳韧度

Figure SMS_17
的计算：Instability toughness
Figure SMS_17
Calculation:

Figure SMS_18
Figure SMS_18

其中：in:

Figure SMS_19
Figure SMS_19

式中：

Figure SMS_20
为失稳韧度，单位MPa·m1/2；Fmax为最大荷载，单位kN；E为试验梁11的计算弹性模量，单位GPa；α＝ac/h，ac为临界裂缝长度，单位mm，应按下式计算：Where:
Figure SMS_20
is the instability toughness, unit MPa·m 1/2 ; F max is the maximum load, unit kN; E is the calculated elastic modulus of the test beam 11, unit GPa; α＝ ac /h, ac is the critical crack length, unit mm, which should be calculated as follows:

Figure SMS_21
Figure SMS_21

h0为夹式引伸计7与裂缝16之间的距离高度，单位mm；Vc为裂缝16口张开位移临界值，单位mm。 h0 is the height of the distance between the clip-on extensometer 7 and the crack 16, in mm; Vc is the critical value of the opening displacement of the crack 16, in mm.

预制裂缝16的两侧预埋有通水管道，通水管道为金属波纹弯管，通水管道包括进水管道6和出水管道8，在试验梁11内部为通水管道口14。裂缝密封胶带12为丁基橡胶胶带，夹具2为钢制夹具并通过螺栓夹紧。测压孔15通过使用钢棒在试验梁11内部预制通孔，测压孔15两端设有螺纹接头3。Water pipes are pre-buried on both sides of the prefabricated crack 16. The water pipes are metal corrugated elbows. The water pipes include an inlet pipe 6 and an outlet pipe 8. Inside the test beam 11 is a water pipe opening 14. The crack sealing tape 12 is a butyl rubber tape. The clamp 2 is a steel clamp and is clamped by bolts. The pressure measuring hole 15 is a prefabricated through hole inside the test beam 11 by using a steel rod. Threaded joints 3 are provided at both ends of the pressure measuring hole 15.

张口位移测量支架5包括L形的钢支座和端部缺口的钢棒并通过螺栓连接固定。The opening displacement measuring bracket 5 comprises an L-shaped steel support and a steel rod with a notch at the end and is fixed by bolt connection.

水压采集装置4为压力变换器。的声发射采集装置为粘贴在试验梁11表面的高频声发射传感器。荷载量测装置是荷载传感器，应变测量装置是粘贴在预制裂缝16尖端两侧的电阻应变片。The water pressure collection device 4 is a pressure transducer. The acoustic emission collection device is a high-frequency acoustic emission sensor pasted on the surface of the test beam 11. The load measurement device is a load sensor, and the strain measurement device is a resistance strain gauge pasted on both sides of the tip of the prefabricated crack 16.

本发明的不局限于上述实施例。凡采用等同替换形成的技术方案，均落在本发明要求的保护范围。The present invention is not limited to the above embodiments. Any technical solution formed by equivalent replacement falls within the protection scope required by the present invention.

Claims (7)

1. The method for testing the concrete fracture process under the action of different water pressures is characterized by comprising the following steps of:
1) Wrapping a crack sealing adhesive tape at a crack prefabricated by a test beam, clamping the crack sealing adhesive tape by using a clamp, wherein a pressure measuring hole is arranged in a fracture process area of the test beam, and water pressure measuring devices are arranged at two ends of the pressure measuring hole; water pipes are pre-buried at two sides of the prefabricated crack, and are metal corrugated bent pipes;
2) The midpoint of the top surface of the crack sealing adhesive tape is used as a force application point, a load F is applied to the test beam by pre-pressurizing water, and the maximum load F required to be applied is measured by a load measuring device max The crack initiation load F is measured by a strain measuring device ini ；
3) Opening displacement measuring brackets are respectively arranged at the bottom end and the tip end of the prefabricated crack, a clamp type extensometer is arranged on the displacement measuring brackets, and an acoustic emission detector is arranged on the test beam;
4) Calculating the fracture toughness according to the following formula
Figure QLYQS_1
And instability toughness->
Figure QLYQS_2
Fracture toughness
Figure QLYQS_3
Is calculated by (1):
Figure QLYQS_4
wherein:
Figure QLYQS_5
wherein: f (F) ini The unit is kN for the crack initiation load; alpha 0 ＝a 0 /h，a 0 Is the initial fracture length; s is the span between two supports of the test beam, and the unit is m; t is the thickness of the test beam, and the unit is m; h is the height of the test beam, and the unit is m; m is the mass between the test beam supports, and the total mass of the test beam is converted into unit kg according to the S/L ratio; l is the length of the test beam, and the unit is m; g is gravity acceleration of 9.8m/s 2 ，
Instability toughness
Figure QLYQS_6
Is calculated by (1):
Figure QLYQS_7
wherein:
Figure QLYQS_8
wherein α=a c /h，a c For critical crack length, in mm, the following formula should be used:
Figure QLYQS_9
wherein: f (F) max Is the maximum load, in kN; e is the calculated elastic modulus of the test beam, and the unit is GPa; h is a 0 The height of the distance between the clamp type extensometer and the crack is in mm; v (V) c Is the crack opening displacement critical value.
2. The method for testing the concrete fracture process under different hydraulic pressures according to claim 1, wherein the method comprises the following steps: the crack sealing adhesive tape is a butyl rubber adhesive tape, and the clamp is a steel clamp and is clamped by a bolt.
3. The method for testing the concrete fracture process under different hydraulic pressures according to claim 1, wherein the method comprises the following steps: the pressure measuring hole is prefabricated through holes in the test beam by using a steel bar, and threaded connectors are arranged at two ends of the pressure measuring hole.
4. The method for testing the concrete fracture process under different hydraulic pressures according to claim 1, wherein the method comprises the following steps: the opening displacement measuring bracket comprises an L-shaped steel support and a steel rod with a notch at the end part and is fixedly connected through bolts.
5. The method for testing the concrete fracture process under different hydraulic pressures according to claim 1, wherein the method comprises the following steps: the water pressure acquisition device is a pressure transducer.
6. The method for testing the concrete fracture process under different hydraulic pressures according to claim 1, wherein the method comprises the following steps: the acoustic emission detector is a high-frequency acoustic emission sensor stuck on the surface of the test beam.
7. The method for testing the concrete fracture process under different hydraulic pressures according to claim 1, wherein the method comprises the following steps: the load measuring device is a load sensor, and the strain measuring device is a resistance strain gauge stuck to two sides of the tip of the prefabricated crack.
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