CN117405586B - Concrete and rock sliding friction coefficient testing system and testing method - Google Patents
Concrete and rock sliding friction coefficient testing system and testing method Download PDFInfo
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- 238000012360 testing method Methods 0.000 title claims abstract description 147
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- 238000009412 basement excavation Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N19/00—Investigating materials by mechanical methods
- G01N19/02—Measuring coefficient of friction between materials
Abstract
The invention discloses a system and a method for testing sliding friction coefficient of concrete and rock, wherein the testing system comprises a base, a frame arranged on the base, a swing rod rotatably connected to the frame, a test piece and a pressure adjusting module, wherein the pressure adjusting module comprises a first-stage lever and a second-stage lever, the output end of the first-stage lever is connected with the input end of the second-stage lever through an elastic element, and the output end of the second-stage lever is connected with the test piece; when the displacement is input to the input end of the first-stage lever, the elastic element applies elastic force to the second-stage lever and enables the output end of the elastic element to apply pressure along the first direction to the test piece. The pressure adjusting module of the invention amplifies output force through the lever mechanism, and can provide large output force through the combination of the two-stage lever and the elastic element and small input displacement, thereby realizing the application of positive pressure to a test piece and the measurement of the sliding friction coefficient through a pendulum test, having high measuring accuracy and good repeatability and being applicable to bedrock under different conditions.
Description
Technical Field
The invention relates to the technical field of geotechnical engineering, in particular to a system and a method for testing sliding friction coefficients of concrete and rock.
Background
Along with the steady and high-speed increase of the economy in China, the demand for transportation is continuously increased, and bridges, particularly, extra-large bridges crossing the river and the sea are used as key projects in traffic projects, so that rapid development is achieved. The suspension bridge has the largest spanning capacity in all bridge types and has the advantage of attractive appearance, and becomes one of the main selection modes for large-span bridge construction. The anchorage is an important component part of the suspension bridge and is one of the most critical bearing components, taking the gravity type anchorage which is most commonly used at present as an example, the vertical component force of the main cable tension is balanced by means of dead weight, and the horizontal component force of the main cable tension is balanced by means of frictional resistance between the anchorage and the foundation. The friction coefficient between the anchorage foundation and the foundation is one of key factors affecting the safety and stability of the whole suspension bridge, and the friction coefficient is scientifically and reasonably determined, so that the method is a primary premise for carrying out the design of the size and the type of the gravity anchor and carrying out the anti-skid stability checking calculation. Therefore, the friction coefficient between the anchorage and the foundation is accurately measured, and the method has important significance for determining a reasonable economic anchorage foundation scheme, improving the comprehensive competitiveness of a suspension bridge scheme and guaranteeing the safety of bridge construction and operation period.
In the prior art, the way for obtaining the friction coefficient of the anchorage mainly comprises two ways of taking values according to experience and taking values according to experiments. The empirical value-taking method is mainly based on the current standard and the geological conditions of site engineering under the condition that experimental data are not available, so that the value-taking method is inaccurate. And the test values include in-situ experiments and model experiments: according to the engineering rock mass test method standard, the friction coefficient between the concrete and the rock mass can be measured through the direct shear test of the contact surface of the concrete of the anchor foundation filling core and the rock mass. The test requires working face excavation on bedrock, concrete test block casting on site, and a loading system and a counter-force system to be configured, which takes more than ten days, is long in time, has hundreds of thousands of expenses and high cost, and is difficult to match with site construction progress. In the indoor triaxial test, although the friction coefficient can be quantitatively tested, a certain deviation can occur in the test result due to the change of the stress environment after sampling.
The pendulum friction coefficient tester is a dynamic pendulum impact type test system which is developed based on the principle that the potential energy of pendulum is equal to the work done by overcoming the friction of a road surface in the process of sliding a rubber sheet arranged at the tail end of a swing arm across the road surface and is used for evaluating the anti-sliding capability and friction coefficient of a bituminous pavement, a marking line or other material test piece in a wet state. The pendulum friction coefficient tester is simple to operate and stable in data, but the test system is mainly used for testing friction between rubber and asphalt, and can not simulate the stress condition of an anchorage, so that the pendulum friction coefficient tester can not be used for measuring the friction coefficient of the anchorage.
In summary, in the existing method for obtaining the friction coefficient of the anchorage of the suspension bridge, the problems of inaccurate empirical value-taking method, high difficulty in experimental value-taking and weak applicability are solved, and it is necessary to develop a quick and economical field test technology.
Disclosure of Invention
Aiming at the defects or improvement demands of the prior art, the invention aims to provide a system and a method for testing the sliding friction coefficient of concrete and rock, wherein a positive pressure is applied to a test piece through a pressure adjusting module, so that the test piece can finish the measurement of the sliding friction coefficient under the condition of the positive pressure, wherein the test piece adopts the concrete test piece, the invention can well simulate the stressed environment of the overlying pressure of an anchorage, and the friction coefficient of the anchorage can be rapidly and accurately measured.
To achieve the purpose, the invention adopts the following technical scheme:
as one aspect of the present invention, there is provided a system for testing sliding friction coefficient of concrete and rock, comprising a base, a frame provided on the base, a swing link rotatably connected to the frame, a test piece connected to the end of the swing link, and a pressure adjustment module provided on the swing link, the pressure adjustment module comprising a first-stage lever and a second-stage lever, an output end of the first-stage lever and an input end of the second-stage lever being connected by an elastic element, an output end of the second-stage lever being connected to the test piece;
when displacement is input to the input end of the first-stage lever, the elastic element applies elastic force to the second-stage lever and enables the output end of the elastic element to apply pressure along a first direction to the test piece, and the test piece subjected to the pressure along the first direction and the bedrock to be tested are enabled to finish sliding friction coefficient measurement through movement of the swing rod.
Further, the pressure adjusting module further comprises an input mechanism, wherein the input mechanism comprises a micro adjusting assembly and a pressure adjusting piece, and the pressure adjusting piece is arranged on the micro adjusting assembly and is in high-pair contact with the input end of the first-stage lever;
the miniature adjusting assembly is rotated to drive the pressure adjusting piece to move along a straight line, and displacement is input to the input end of the first-stage lever.
Further, the pressure adjustment module further comprises an output mechanism;
the output mechanism comprises a pressure adjusting slide block, one end of the pressure adjusting slide block is in high-pair contact with the output end of the second-stage lever, the other end of the pressure adjusting slide block is connected with the test piece, and the pressure adjusting slide block is arranged to be slidable along a first direction and used for converting acting force of the output end of the second-stage lever into pressure along the first direction.
Further, the test piece is a concrete test piece.
Further, the test system also comprises a swing rod adjusting module, wherein the swing rod adjusting module comprises a displacement adjusting mechanism and a swing shaft, the displacement adjusting mechanism is arranged on the frame and is connected with the swing shaft, and the swing shaft is connected with the swing rod;
the displacement adjusting mechanism is used for adjusting the vertical position of the swing shaft, so as to adjust the vertical position of the swing axis of the swing rod.
Further, the displacement adjustment mechanism is a ball screw mechanism.
Further, the test system also comprises an information acquisition and display module;
the output mechanism further comprises a force transducer which is arranged between the pressure adjusting slide block and the test piece and used for acquiring the pressure of the test piece along the first direction;
the information acquisition and display module is connected with the force transducer and used for acquiring pressure data.
Further, the swing rod adjusting module further comprises a photoelectric encoder, wherein the photoelectric encoder is arranged at the tail part of the swing shaft and is used for acquiring the rotation angle and the rotation speed of the swing rod;
the information acquisition and display module is also used for acquiring the rotation angle and the rotation speed, and further determining the rock friction coefficient according to a rock friction coefficient calculation formula.
Further, the base comprises a bottom plate, leveling feet and a level;
four leveling feet are respectively arranged at four corners of the bottom plate and used for leveling the bottom plate; the level gauge is arranged on the bottom plate and used for checking whether the bottom plate is leveled or not.
As another aspect of the present invention, there is also provided a method for testing a sliding friction coefficient of concrete and rock, comprising:
s100, placing a test system on a bedrock to be tested, leveling and zeroing the test system, adjusting the swing axis of the swing rod through a swing rod adjusting module, and obtaining a calibration displacement value of the swing rod adjusting module when the calibration sliding length is reached;
s200, adjusting the swing axis of the swing rod through a swing rod adjusting module to enable the swing rod to freely droop, applying pressure along a first direction to a test piece through a pressure adjusting module, and observing through an information acquisition display module until the pressure value reaches a test requirement;
s300, manually controlling the swing rod to be placed at a horizontal position, adjusting the displacement value of the swing rod adjusting module to the calibrated displacement value, and releasing the swing rod;
s400, repeatedly carrying out a test experiment according to the steps S-S, acquiring pressure data, rotation angle data and rotation speed data through an information acquisition and display module, and further calculating the rock friction coefficient according to a rock friction coefficient calculation formula and calculating an average value.
The invention has the beneficial effects that:
the invention provides a system and a method for testing sliding friction coefficient of concrete and rock, wherein the testing system comprises a base, a frame arranged on the base, a swing rod rotatably connected to the frame, a test piece and a pressure adjusting module, wherein the test piece is connected to the tail end of the swing rod, and the pressure adjusting module is arranged on the swing rod; the pressure adjusting module comprises a first-stage lever and a second-stage lever, the output end of the first-stage lever is connected with the input end of the second-stage lever through an elastic element, and the output end of the second-stage lever is connected with the test piece; when the displacement is input to the input end of the first-stage lever, the elastic element applies elastic force to the second-stage lever and enables the output end of the elastic element to apply pressure along the first direction to the test piece.
On one hand, the positive pressure of the test piece is controlled by the pressure adjusting module, and then the determination of the sliding friction coefficient of the concrete test piece subjected to the positive pressure and the bedrock to be tested is completed by the pendulum test, so that the method has high measurement accuracy and good repeatability, and can be suitable for bedrocks under different conditions.
On the other hand, in the pressure adjusting module, the output force is amplified through the lever mechanism, and the combination of the two stages of levers and the elastic element is utilized, so that the large output force can be provided by small input displacement.
Additional aspects and advantages of the application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the application.
Drawings
The foregoing and/or additional aspects and advantages of the present application will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a schematic diagram of a system for testing the sliding friction coefficient of concrete and rock in an embodiment of the invention;
FIG. 2 is a schematic view of a base in an embodiment of the invention;
FIG. 3 is a schematic diagram of a swing link adjustment module according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a swing link adjustment module according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of a swing link adjustment module according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of a pressure adjustment module according to an embodiment of the present invention;
FIG. 7 is a force diagram of a pressure adjustment module according to an embodiment of the invention;
FIG. 8 is a flow chart of a method for testing the sliding friction coefficient of concrete and rock in an embodiment of the invention;
FIG. 9 is a schematic diagram of a method for testing the sliding friction coefficient of concrete and rock according to an embodiment of the invention;
wherein:
1. a base; 2. a frame; 3. swing rod; 4. a test piece; 5. a pressure adjustment module; 6. the swing rod adjusting module; 7. an information acquisition and display module;
11. a bottom plate; 12. leveling the ground feet; 13. a level gauge;
30. a swing rod body; 31. a swing rod sealing shell;
51 first stage lever; 52. a second stage lever; 53 an elastic element; 54. an input mechanism; 55. an output mechanism 55;
541. a miniature adjustment assembly; 542. a pressure adjusting member; 551. a pressure adjusting slide block; 552. a load cell;
61. a displacement adjustment mechanism; 62. a swing shaft; 63. a photoelectric encoder; 64. a positioning and fixing mechanism; 65. swinging the dial; 66. and the swing axle center adjusting mechanism.
Detailed Description
The invention is described in further detail below with reference to the drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting thereof. It should be further noted that, for convenience of description, only some, but not all of the structures related to the present invention are shown in the drawings.
In the description of the present invention, unless explicitly stated and limited otherwise, the terms "connected," "connected," and "fixed" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless expressly stated otherwise, as understood by those skilled in the art. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It will be understood by those skilled in the art that all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs unless defined otherwise. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
Based on the problems existing in the measurement of the anchorage friction coefficient of the suspension bridge in the prior art, the application provides a system and a method for testing the sliding friction coefficient of concrete and rock.
Example 1
Referring to fig. 1-6, an embodiment of the present application provides a system for testing sliding friction coefficient of concrete and rock, which includes a base 1, a frame 2, a swing rod 3, a test piece 4, a pressure adjusting module 5, a swing rod adjusting module 6 and an information collecting and displaying module 7.
The base 1 is a load-bearing foundation of the test system of the present embodiment, and as shown in fig. 2, the base 1 includes a base plate 11, leveling feet 12, and a level 13. Four leveling feet 12 are respectively arranged at four corners of the bottom plate 11, and a level gauge 13 is arranged on the bottom plate 11 and used for checking whether the bottom plate 11 is leveled or not. When the test system is leveled, the bottom plate 11 is leveled by adjusting the four leveling feet 12, and meanwhile, air bubbles in the level 13 are observed, and the bottom plate 11 is leveled when the air bubbles in the level 13 are centered.
The bottom of the frame 2 is connected with the base 1, the swing rod 3 is connected to the middle part of the frame 2, and the frame 2 is the supporting foundation of the test system in the embodiment. Preferably, the bottom of the frame 2 is fixedly connected to the base 1 by welding.
A swing rod adjusting module 6 is arranged between the swing rod 3 and the frame 2, and the swing rod adjusting module 6 is used for adjusting the vertical position of the swing axis of the swing rod 3. Referring to fig. 3 to 5, the swing link adjustment module 6 includes a displacement adjustment mechanism 61, a swing shaft center 62, a photoelectric encoder 63, a positioning and fixing mechanism 64, a swing dial 65, and a swing shaft center adjustment mechanism 66.
In the test system of the present embodiment, the positioning and fixing mechanism 64 is fixedly connected to the middle part of the frame 2, the displacement adjusting mechanism 61 is mounted on the positioning and fixing mechanism 64, the swing axis adjusting mechanism 66 is disposed on the displacement adjusting mechanism 61, and the swing shaft 62 is mounted on the swing axis adjusting mechanism 66 through a bearing.
Further, the displacement adjustment mechanism 61 is a ball screw mechanism, and the swing axis adjustment mechanism 66 is provided on a slide table of the displacement adjustment mechanism 61. Specifically, when the vertical position of the swing axis of the swing rod 3 is adjusted by the swing rod adjusting module 6, the handle in the displacement adjusting mechanism 61 is rotated to drive the sliding table to perform high-precision vertical displacement in the vertical direction, and the swing axis adjusting mechanism 66 and the swing shaft 62 vertically move along with the sliding table on the track. Thereby realizing the adjustment of the vertical position of the swing axis of the swing rod 3.
Further, the photoelectric encoder 63 is disposed at the tail of the swing shaft 62, and is used for obtaining the rotation angle and rotation speed of the swing rod 3, so as to provide detection support for the test method. In the present embodiment, the photoelectric encoder 63 employs a high-precision photoelectric encoder.
In this embodiment, the end of the swing rod 3 is connected with a test piece 4, and the test piece 4 is a concrete test piece.
The pressure adjusting module 5 is arranged on the swing rod 3 and is connected with the test piece 4. The pressure adjustment module 5 is one of the core components of the test system for applying a force in a first direction to the test piece 4. The first direction is a direction perpendicular to the top surface of the test piece 4, and the force applied to the test piece 4 along the first direction is that of applying a positive pressure to the test piece 4. Specifically, as shown in fig. 6, the pressure adjustment module 5 includes an input mechanism 54, a first-stage lever 51, an elastic member 53, a second-stage lever 52, and an output mechanism 55, which are connected in this order.
Referring to fig. 6, the swing link 3 includes a swing link body 30 and a swing link sealing case 31, and the pressure adjusting module 5 is provided on the swing link body 30, and the swing link sealing case 31 is used for sealing the pressure adjusting module 5. In this embodiment, the input mechanism 54 is mounted on the swing rod body 30, the input mechanism 54 includes a micro-adjustment assembly 541 and a pressure adjustment member 542, and the pressure adjustment member 542 is disposed on the micro-adjustment assembly 541 and is in high-pair contact with the input end of the first-stage lever 51. Wherein, the high pair contact refers to the motion constraint formed by point contact or line contact between two members. Further, the micro-adjustment assembly 541 is rotated to drive the pressure adjusting member 542 to move along a straight line, thereby inputting displacement to the input end of the first-stage lever 51. Preferably, the micro-adjustment assembly 541 is a screw-slider transmission assembly, and the pressure adjustment member 542 is fixedly connected to the slider.
Further, the first-stage lever 51 and the second-stage lever 52 are both rotatably connected to the swing rod body 30, the output end of the first-stage lever 51 and the input end of the second-stage lever 52 are connected through an elastic element 53, and the output end of the second-stage lever 52 is connected to the test piece 4. Wherein, when a displacement is input to the input end of the first-stage lever 51, the elastic member 53 applies an elastic force to the second-stage lever 52 and causes the output end thereof to apply a pressure in the first direction to the test piece 4. Preferably, the elastic element 53 is a spring. It will be appreciated that the first stage lever 51 and the second stage lever 52 in this embodiment are both configured to amplify force, and thus both have long arm ends at their input ends and short arm ends at their output ends.
Further, an output mechanism 55 is provided between the second-stage lever 52 and the test piece 4, the output mechanism 55 includes a pressure adjusting slider 551 and a load cell 552, one end of the pressure adjusting slider 551 is in high-pair contact with the output end of the second-stage lever 52, and the other end is connected with the test piece 4, and the pressure adjusting slider 551 is configured to be slidable along a first direction for converting the acting force of the output end of the second-stage lever 52 into a pressure along the first direction. It should be noted that, in this embodiment, the pressure adjusting slider 551 is provided with a flat end and a tip along the first direction, where the flat end is connected to the test piece 4 and parallel to the surface of the test piece 4, and the tip is in high pair contact with the output end of the second level lever 52, so as to ensure that a positive pressure is applied uniformly to the top of the test piece 4. The load cell 552 is disposed between the pressure adjusting slider 551 and the test piece 4, and is used for acquiring the pressure applied to the test piece 4 along the first direction.
When the pressure adjusting module 5 increases the positive pressure on the test piece 4, the micro-adjusting unit 541 is rotated to move the pressure adjusting member 542 downward, to drive the output end of the first-stage lever 51 to rotate in a direction away from the input end of the second-stage lever 52, the elastic member 53 is extended, the elastic potential energy is increased, the elastic force applied to the input end of the second-stage lever 52 is increased, so that the interaction force between the pressure adjusting slider 551 and the output end of the second-stage lever 52 is increased, and finally the positive pressure transferred to the test piece 4 is increased. Similarly, the process of the pressure adjustment module reducing the positive pressure on the test piece 4 is reversed from that described above.
The force diagram of the pressure adjusting module 5 when applying positive pressure to the test block 4 is shown in fig. 7, and in this embodiment, the pressure adjusting module 5 needs to be able to provide a certain range of forward pressure, so that the two-stage lever and elastic element are adopted.
After the dimensional parameters of the first stage lever 51 and the second stage lever 52 are determined, the second stage lever52 and the pressure adjusting slider 551F 3 Can be actuated by the force of the input of the first-stage lever 51F 1 Parameters of the elastic element 53 (including the spring wire diameter D, the spring pitch diameter D and the initial length of the spring in this embodiment)l 0 ) And geometric dimensioning of the device:
；
after the geometry of the device and the spring geometry parameters are determined, the device is changedF 1 Can obtain correspondingF 3 。
The information collection and display module 7 is connected with the pressure adjustment module 5 and the swing rod adjustment module 6, and is used for obtaining pressure data measured by the force sensor 552, rotation angle data measured by the photoelectric encoder 63 and rotation speed data. Further, according to the pressure data, the rotation angle data, the rotation speed data and the reference parameters of the test system, the rock friction coefficient is determined based on a rock friction coefficient calculation formula. The information collection and display module 7 is further configured to obtain a displacement value of the displacement adjustment mechanism 61.
As a feasible real-time mode, the information acquisition and display module 7 can automatically record and display pressure data, rotation angle data and rotation speed data in the test process by adopting an industrial control host, singly measure the friction coefficient of the rock mass, and can output test data of multiple points in the form of curves and test documents.
In general, the pressure adjusting module adjusts the two-stage lever (and the elastic element) to control the positive pressure of the concrete test piece, based on sliding friction under the positive pressure of the pendulum test design, test data are collected through the high-frequency data collecting sensor, and data collection, processing and display are realized through the industrial control host, so that the workload of friction coefficient test between the suspension bridge anchorage basement rock and concrete is greatly reduced, market demands can be better met by the technology, and the method has a large popularization value in actual engineering.
Example 2
The embodiment provides a method for testing sliding friction coefficient of concrete and rock, and a flow chart of the testing method is shown in fig. 8, and the method comprises steps S100-S400.
S100, placing the test system on a bedrock to be tested, leveling and zeroing the test system, adjusting the swing axis of the swing rod through the swing rod adjusting module, and obtaining the calibration displacement value of the swing rod adjusting module when the calibration sliding length is reached.
When in field test, the test system is firstly placed on the ground of bedrock, the bottom plate is leveled through four leveling feet, and the leveling result can be checked through a level gauge, so that the bottom plate is ensured to be in a horizontal plane.
And the vertical position of the swing axis of the swing rod is adjusted by the swing rod adjusting module, and the initial contact line of the test piece and the bedrock to be tested is determined when the swing rod vertically sags.
The swinging rod is controlled manually, so that the swinging rod slowly rotates downwards from a horizontal position, the vertical position of the swinging axis of the swinging rod is adjusted through the swinging rod adjusting module, and a calibration contact line of the test piece and the bedrock to be tested is determined, wherein the distance between the calibration contact line and the initial contact line is L (the L is determined by equipment calibration in factory and is a fixed value). And recording the calibration displacement value of the swing rod adjusting module at the moment, wherein the calibration displacement value can be read out by a scale on the positioning and fixing mechanism or by an industrial information acquisition and display module.
And S200, adjusting the swing axis of the swing rod through a swing rod adjusting module to enable the swing rod to freely droop, applying pressure along a first direction to a test piece through a pressure adjusting module, and observing through an information acquisition display module until the pressure value reaches the test requirement.
The positive pressure on the test piece is reduced by the pressure adjustment module. The swing axis of the swing rod is adjusted through the swing rod adjusting module, so that the swing rod can freely droop. And gradually increasing the positive pressure of the test piece through the pressure adjusting module according to the positive pressure required by the test, and observing the pressure value in the screen of the industrial control host until the pressure value reaches the test requirement.
S300, manually controlling the swing rod to be placed at the horizontal position, adjusting the displacement value of the swing rod adjusting module to the calibrated displacement value, and releasing the swing rod.
S400, repeatedly carrying out a test experiment according to the steps S100-S300, acquiring pressure data, rotation angle data and rotation speed data through an information acquisition and display module, and further calculating the friction coefficient of the rock mass according to a rock mass friction coefficient calculation formula and calculating an average value.
The technical principle of the test method is shown in figure 9, wherein the mass center of the swinging rod-test piece isThe friction force between the test piece and the bedrock to be tested is +.>Friction coefficient +.>The method can be obtained by the parameters:
；
wherein,for friction coefficient>Is the length of the swinging rod>For the moment of inertia of the pendulum rod test piece +.>For the normal force between test piece and bedrock to be tested, < >>Is the distance between the mass center of the swing rod-test piece and the swing axis of the swing rod, < > and the mass center of the swing rod-test piece>Terminating the swinging motion of the pendulumAngle (S)/(S)>The initial included angle between the swing rod and the vertical direction when the test piece is initially contacted with the bedrock to be tested is +.>The mass of the pendulum rod-test piece is the whole mass of the pendulum rod-test piece.
In this embodiment, the normal force between the test piece and the bedrock to be tested is measured by the load cell, the initial included angle and the swing termination angle are measured by the high-precision photoelectric encoder, and other parameters are determined by the equipment geometry or set during the test.
It should be understood that, although the steps in the flowcharts of the figures are shown in order as indicated by the arrows, these steps are not necessarily performed in order as indicated by the arrows. The steps are not strictly limited in order and may be performed in other orders, unless explicitly stated herein. Moreover, at least some of the steps in the flowcharts of the figures may include a plurality of sub-steps or stages that are not necessarily performed at the same time, but may be performed at different times, the order of their execution not necessarily being sequential, but may be performed in turn or alternately with other steps or at least a portion of the other steps or stages.
The foregoing is only a partial embodiment of the present application, and it should be noted that, for a person skilled in the art, several improvements and modifications can be made without departing from the principle of the present application, and these improvements and modifications should also be considered as the protection scope of the present application.
Claims (10)
1. The system for testing the sliding friction coefficient of concrete and rock comprises a base (1), a frame (2) arranged on the base (1), a swing rod (3) rotatably connected to the frame (2), a test piece (4) connected to the tail end of the swing rod (3) and a pressure adjusting module (5) arranged on the swing rod (3), and is characterized in that the swing rod (3) comprises a swing rod body (30) and a swing rod sealing shell (31), the pressure adjusting module (5) comprises a first-stage lever (51), a second-stage lever (52), an input mechanism (54) and an output mechanism (55), the output end of the first-stage lever (51) is connected with the input end of the second-stage lever (52) through an elastic element (53), the output end of the second-stage lever (52) is connected with the test piece (4), the first-stage lever (51) and the second-stage lever (52) are rotatably connected to the swing rod body (30), the input mechanism (54) is arranged on the body (30), and the output mechanism (55) is arranged between the first-stage lever (52) and the test piece (4).
When displacement is input to the input end of the first-stage lever (51), the elastic element (53) applies elastic force to the second-stage lever (52) and enables the output end of the elastic element to apply pressure along a first direction to the test piece (4), and the test piece (4) subjected to the pressure along the first direction and the bedrock to be tested are enabled to complete sliding friction coefficient measurement through movement of the swing rod (3).
2. The system for testing the sliding friction coefficient of concrete and rock according to claim 1, wherein the input mechanism (54) comprises a micro-adjustment assembly (541) and a pressure adjustment member (542), the pressure adjustment member (542) being provided on the micro-adjustment assembly (541) and in line contact with the input end of the first-stage lever (51);
wherein, the micro adjusting assembly (541) is rotated to drive the pressure adjusting member (542) to move along a straight line, so as to input displacement to the input end of the first-stage lever (51).
3. The system according to claim 2, characterized in that the output mechanism (55) comprises a pressure adjustment slider (551), one end of the pressure adjustment slider (551) being in line contact with the output end of the second-stage lever (52), the other end being connected to the test piece (4), the pressure adjustment slider (551) being arranged to be slidable in a first direction for converting the force of the output end of the second-stage lever (52) into a pressure in the first direction.
4. A concrete and rock sliding friction coefficient testing system according to any one of claims 1-3, characterized in that the test piece (4) is a concrete test piece.
5. A concrete and rock sliding friction coefficient testing system according to claim 3, characterized in that the testing system further comprises a swing rod adjusting module (6), the swing rod adjusting module (6) comprises a displacement adjusting mechanism (61) and a swing shaft (62), the displacement adjusting mechanism (61) is arranged on the frame (2), the displacement adjusting mechanism (61) is connected with the swing shaft (62), and the swing shaft (62) is connected with the swing rod (3);
the displacement adjusting mechanism (61) is used for adjusting the vertical position of the swing shaft (62) so as to adjust the vertical position of the swing axis of the swing rod (3).
6. The system according to claim 5, wherein the displacement adjustment mechanism (61) is a ball screw mechanism.
7. The system for testing the sliding friction coefficient of concrete and rock according to claim 6, wherein the system further comprises an information acquisition and display module (7);
the output mechanism (55) further comprises a force transducer (552), wherein the force transducer (552) is arranged between the pressure adjusting slide block (551) and the test piece (4) and is used for acquiring the pressure applied to the test piece (4) along the first direction;
the information acquisition and display module (7) is connected with the force transducer (552) and is used for acquiring pressure data.
8. The system for testing the sliding friction coefficient of concrete and rock according to claim 7, wherein the swing rod adjusting module (6) further comprises a photoelectric encoder (63), and the photoelectric encoder (63) is arranged at the tail of the swing shaft (62) and is used for acquiring the rotation angle and the rotation speed of the swing rod (3);
the information acquisition and display module (7) is also used for acquiring the rotation angle and the rotation speed, and further determining the rock friction coefficient according to a rock friction coefficient calculation formula.
9. A system for testing the sliding friction coefficient of concrete and rock according to any one of claims 1 to 3, characterized in that the foundation (1) comprises a bottom plate (11), leveling feet (12) and a level (13);
four leveling feet (12) are respectively arranged at four corners of the bottom plate (11) and used for leveling the bottom plate (11); the level gauge (13) is arranged on the bottom plate (11) and is used for checking whether the bottom plate (11) is leveled or not.
10. A method for testing the sliding friction coefficient of concrete and rock, which is characterized by being implemented by using the system for testing the sliding friction coefficient of concrete and rock according to any one of claims 5-8, and comprising the following steps:
s100, placing a test system on a bedrock to be tested, leveling and zeroing the test system, adjusting the swing axis of the swing rod through a swing rod adjusting module, and obtaining a calibration displacement value of the swing rod adjusting module when the calibration sliding length is reached;
s200, adjusting the swing axis of the swing rod through a swing rod adjusting module to enable the swing rod to freely droop, applying pressure along a first direction to a test piece through a pressure adjusting module, and observing through an information acquisition display module until the pressure value reaches a test requirement;
s300, manually controlling the swing rod to be placed at a horizontal position, adjusting the displacement value of the swing rod adjusting module to the calibrated displacement value, and releasing the swing rod;
s400, repeatedly carrying out a test experiment according to the steps S100-S300, acquiring pressure data, rotation angle data and rotation speed data through an information acquisition and display module, and further calculating the friction coefficient of the rock mass according to a rock mass friction coefficient calculation formula and calculating an average value.
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| CN108303328A (en) * | 2018-04-28 | 2018-07-20 | 四川大学 | The rock mechanics response test system of simulation deep ground complex environment |
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| DE10066365B4 (en) * | 1999-07-12 | 2013-02-28 | Fuji Xerox Co., Ltd. | A printing apparatus having a buffer section and a feed force adjusting section for printing on a continuous web |
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