CN114813375B - Test device for simulating electroosmosis to reduce pile-soil friction mechanism - Google Patents
Test device for simulating electroosmosis to reduce pile-soil friction mechanism Download PDFInfo
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- 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
- G01N3/24—Investigating strength properties of solid materials by application of mechanical stress by applying steady shearing forces
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Abstract
The invention discloses a test device for simulating an electroosmosis effect to reduce a pile-soil friction mechanism, which comprises a hydraulic loading system, a data collector, a voltage regulating system, a power supply, a box body and a shear test device, wherein the hydraulic loading system, the data collector, the voltage regulating system and the power supply are arranged at one end of an inner cavity of the box body, and the shear test device is arranged on the rest part of the inner cavity of the box body; the top surface of the box body is fixedly connected with a vertical loading unit; the shear test device comprises a test mechanism and a driving detection unit; the driving detection units are arranged on two opposite sides of the test mechanism; the driving detection unit is fixedly connected with the box body; the method can realize laboratory verification of clay sample direct shear test, and obtain pile-soil friction data under the influence of various factors such as different voltages, different soil conditions, different pressures and the like, thereby achieving the purpose of exploring electroosmosis to reduce pile-soil friction mechanism, and finally realizing suggestion and guidance on simulation of practical engineering such as offshore wind power single pile and the like.
Description
Technical Field
The invention relates to the technical field of simulation experiments, in particular to a test device for simulating an electroosmosis effect to reduce a pile-soil friction mechanism.
Background
At the beginning of the 19 th century, russian scholar reus discovered the electroosmosis phenomenon in clay. Casagrandel realized that electro-osmosis treatment has a good effect on improving shear strength and stability of fine soil in the 30 s of the 20 th century, and the electro-osmosis technology is applied to soft soil reinforcement in geotechnical engineering. Later, various scholars carry out a great deal of research work on the engineering, and have cases of successful application in the engineering. The electroosmosis method has the advantages of high reinforcement speed, good reinforcement effect on fine particles and low-permeability soil and the like, and has the effect of draining weak bound water in soil.
Along with the development and construction process of China in inland lake Hunan or river-facies areas, the soft soil needs to be subjected to drainage consolidation treatment, so that the compressibility of the soft soil is reduced, and the bearing capacity of the soft soil is improved. In addition, in the offshore construction and the port construction of China, sludge dredging and foundation reinforcement are often carried out. When the traditional surcharge preloading or vacuum preloading method is adopted for relevant work, the efficiency is low and the time is long. The electroosmosis method gradually becomes a soft foundation treatment, slope reinforcement and sludge dehydration treatment technology with great potential and engineering practical value.
The direct shear test is a test for obtaining an index of shear strength of soil by directly applying normal pressure and shear stress to a predetermined shear plane, respectively. The shear strength of soil is the ultimate shear strength of the soil when one part of the soil body slides relative to the other part of the soil body under the action of external force. The test is that a plurality of samples of the same soil are respectively and directly applied with horizontal shearing force along a fixed shearing surface under the action of different vertical pressures to obtain shearing stress during damage, and then the soil shearing strength index is determined according to coulomb's law: internal friction angle and cohesion.
The principle of reducing pile-soil friction by electroosmosis is that the total stress of soil is equal to the sum of effective stress and pore water pressure, and the total stress is unchanged without external force, at the moment, the pore water pressure can be increased at the cathode by electroosmosis, so that the effective stress is reduced, and then the friction is reduced according to a calculation formula of the friction. And the second is that the water separated out from the cathode can form a water film to reduce the friction force. In order to collect and analyze data in the experimental process and research the specific mechanism of reducing pile-soil friction by electroosmosis in the field of offshore wind power single piles, a test device for simulating the mechanism of reducing pile-soil friction by electroosmosis is necessary to fill the blank of operating instruments in a laboratory.
Disclosure of Invention
The invention aims to provide a test device for simulating an electroosmosis effect to reduce a pile-soil friction mechanism, which aims to solve the problems in the prior art, can simulate the electroosmosis effect to reduce the pile-soil friction mechanism in the offshore wind power single-pile engineering field and related fields, so as to explore the mechanism, further simulate the specific engineering condition through the change of different parameters, and finally achieve the guidance and suggestion effect on the engineering.
In order to achieve the purpose, the invention provides the following scheme:
a test device for simulating an electroosmosis effect to reduce a pile-soil friction mechanism comprises a hydraulic loading system, a data collector, a voltage regulating system, a power supply, a box body and a shear test device, wherein the box body and the shear test device are matched with the hydraulic loading system, the data collector, the voltage regulating system and the power supply, the hydraulic loading system, the data collector, the voltage regulating system and the power supply are arranged at one end of an inner cavity of the box body, and the shear test device is arranged at the rest part of the inner cavity of the box body; a vertical loading unit is fixedly connected to the top surface of the box body; the shear test device comprises a test mechanism for carrying out simulation experiments on samples and a driving detection unit for giving a loading force to the test mechanism; the driving detection units are arranged on two opposite sides of the test mechanism; the driving detection unit is fixedly connected with the box body;
the hydraulic loading system is in transmission connection with the driving detection unit and the vertical loading unit respectively; the voltage regulating system is electrically connected with the testing mechanism; the power supply is electrically connected with the hydraulic loading system, the data collector and the voltage regulating system respectively; the data collector is electrically connected with the vertical loading unit and the driving detection unit respectively.
Preferably, the testing mechanism comprises a base; the base is of a box-shaped structure with an open top surface; a bottom plate is arranged at the center of the bottom surface of the inner cavity of the base; the bottom plate is fixedly connected with a cathode connecting piece, and the cathode connecting piece is electrically connected with a cathode electrode; the cathode electrode is electrically connected with the voltage regulating system; a pile foundation simulation bottom plate is placed on the top surface of the bottom plate; an experimental cylinder is placed on the top surface of the pile foundation simulation bottom plate; a movable screen plate is hinged to one side face of the bottom of the experimental cylinder, and the vertical loading unit is arranged at the top end of the inner cavity of the experimental cylinder; a transverse push rod is fixedly connected to the side wall of the experimental cylinder; one end of the transverse push rod is detachably connected with the driving detection unit.
Preferably, the vertical loading unit comprises a support assembly, a vertical hydraulic cylinder, a first pressure sensor and a material pressing assembly; the center of the bracket component is vertically and fixedly connected with the vertical hydraulic cylinder; the bottom end of a hydraulic rod of the vertical hydraulic cylinder is fixedly connected with the first pressure sensor; the bottom surface of the first pressure sensor is fixedly connected with the material pressing component; the first pressure sensor is electrically connected with the data collector; and the vertical hydraulic cylinder is in transmission connection with the hydraulic loading system.
Preferably, the bracket assembly comprises two fixing plates; the two fixing plates are arranged oppositely and fixedly connected through a plurality of stand columns; a through hole is formed in the center of the fixing plate; the vertical hydraulic cylinder is fixedly arranged in the through hole; the two opposite side surfaces of the fixed plate are fixedly connected with T-shaped cores through a plurality of connecting rods respectively; one end of the T-shaped core, which is far away from the connecting rod, is matched with a guide rail in a sliding manner; the bottom surface of the guide rail is fixedly connected with the top surface of the box body.
Preferably, the pressing assembly comprises an anti-slip claw; the top end of the anti-skid claw is fixedly connected with the bottom surface of the first pressure sensor, and the bottom end of the anti-skid claw is detachably connected with a top cover; a porous resistance plate is fixedly connected to the bottom surface of the top cover; the bottom surface of the porous resistance plate is fixedly connected with a graphite net; the graphite net is electrically connected with an anode electrode; the anode electrode is electrically connected with the voltage regulating system; the top cover, the porous resistance plate and the graphite net are respectively matched with the experiment cylinder and in sliding contact with the experiment cylinder.
Preferably, the driving detection unit comprises a displacement sensor, a flat-load hydraulic cylinder and a second pressure sensor; the flat-load hydraulic cylinder is fixedly connected with the bottom surface of the inner cavity of the box body through a strut; the flat-load hydraulic cylinder is in transmission connection with the hydraulic loading system; a hydraulic rod of the flat-load hydraulic cylinder is fixedly connected with the second pressure sensor; the displacement sensor and the second pressure sensor are respectively arranged on two sides of the experiment cylinder; the displacement sensor is opposite to the second pressure sensor; the displacement sensor is fixedly connected with the inner side wall of the box body; one end face of the transverse push rod is arranged opposite to the second pressure sensor; the displacement sensor and the second pressure sensor are respectively electrically connected with the data collector.
Preferably, one end of the inner cavity of the box body is divided into an experiment cavity and four independent placing cavities by a plurality of partition plates; the hydraulic loading system, the data collector, the voltage regulating system and the power supply are respectively arranged in the four placing cavities; the base with the pillar set up in the laboratory cavity bottom surface.
Preferably, the middle part of the bottom surface of the transverse push rod is provided with a abdicating groove; the abdicating groove is in clearance fit with the side wall of the experimental cylinder.
Preferably, the top cover and the bottom plate are made of brass; the area of the top surface of the bottom plate is larger than that of the bottom surface of the experiment cylinder; the bottom plate is provided with two parallel convex ribs; the area of the pile foundation simulation bottom plate is consistent with that of the bottom plate, and two grooves matched with the two parallel convex ribs on the bottom plate are formed in the bottom surface of the pile foundation simulation bottom plate.
Preferably, the material for manufacturing the experimental cylinder is high-resistance high-strength epoxy resin.
The invention has the following technical effects:
1. the invention can carry out electroosmosis treatment on the soil sample, and through the design of the shearing test mechanism, the electroosmosis effect can be carried out by electrifying simultaneously in the shearing test process, thereby simplifying the test process.
2. The invention meets the requirement of directly carrying out electroosmosis in the test mechanism by selecting and designing the material of the test mechanism, can directly carry out acquisition and observation of pile-soil surface friction data in the electroosmosis process, and can carry out simulation of the pile-soil surface friction mechanism under various conditions by replacing a soil body sample and a pile foundation simulation bottom plate through voltage regulation, vertical loading change and the like, thereby being beneficial to multi-factor exploration of the mechanism.
3. The invention uses the power supply, and simplifies the operation steps in the experimental process by installing and using the hydraulic loading system, the pressure sensor and the displacement sensor.
4. The invention is used for simulating the pressure under different depths by changing the vertical loading, the preparation of the soil mass sample simulates the soil mass characteristic under the specific environment, and the pile foundation simulation base plate selects the pile foundation material in the actual engineering, thereby being capable of exploring the most appropriate voltage selection range in the engineering and having the practical engineering significance.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required in the embodiments will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic front view of the present invention.
Fig. 2 is a schematic front view structure diagram of the testing mechanism.
Fig. 3 is a left-side structural schematic diagram of the vertical loading unit.
The method comprises the following steps of 1, hydraulic loading system; 2. a data collection instrument; 3. a voltage regulation system; 4. a power source; 5. a box body; 6. a vertical loading unit; 61. a vertical hydraulic cylinder; 62. a first pressure sensor; 63. a fixing plate; 64. a connecting rod; 65. a T-shaped core; 66. a guide rail; 67. a column; 68. a material pressing component; 681. an anti-slip claw; 682. a top cover; 683. a porous resistance plate; 684. a graphite mesh; 685. a protrusion; 7. a testing mechanism; 71. a base; 72. a brass base plate; 74. a movable screen plate; 75. a test cylinder; 76. a horizontal push rod; 77. a pile foundation simulation base plate; 78. a cathode connection member; 8. a drive detection unit; 81. a displacement sensor; 82. a flat-load hydraulic cylinder; 83. a second pressure sensor; 84. and a support pillar.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
The first embodiment is as follows:
a test device for simulating an electroosmosis effect to reduce a pile-soil friction mechanism comprises a hydraulic loading system 1, a data collector 2, a voltage regulating system 3, a power supply 4, a box body 5 and a shearing test device, wherein the box body 5 and the shearing test device are matched with the components; the hydraulic loading system 1, the data collector 2, the voltage regulating system 3 and the power supply 4 are respectively arranged in the four placing cavities; the shearing test device is arranged on the bottom surface of the experiment cavity; the top surface of the box body 5 is fixedly connected with a vertical loading unit 6; the shearing test device comprises a test mechanism 7 for carrying out simulation experiment on a sample and a driving detection unit 8 for giving load force to the test mechanism 7; the driving detection units 8 are arranged on two opposite sides of the testing mechanism 7; the driving detection unit 8 is fixedly connected with the box body 5;
the hydraulic loading system 1 is in transmission connection with the driving detection unit 8 and the vertical loading unit 6 respectively; the voltage regulating system 3 is electrically connected with the testing mechanism 7; the power supply 4 is respectively electrically connected with the hydraulic loading system 1, the data collector 2 and the voltage regulating system 3; the data collector 2 is electrically connected with the vertical loading unit 6 and the driving detection unit 8 respectively.
Further, the hydraulic loading system 1, the data collector 2, the voltage regulating system 3, and the power supply 4 are all common soil body shear test instruments, which are prior art and are not described herein again.
In a further optimized scheme, the testing mechanism 7 comprises a base 71; the base 71 is a box-shaped structure with an open top surface; a bottom plate 72 is arranged at the center of the bottom surface of the inner cavity of the base 71; a cathode connecting member 78 is fixedly connected to the bottom plate 72, and the cathode connecting member 78 is electrically connected to a cathode (not shown in the drawings); the cathode electrode is electrically connected with the voltage regulating system 3; a pile foundation simulation bottom plate 77 is arranged on the top surface of the bottom plate 72; the experimental cylinder 75 is arranged on the top surface of the pile foundation simulation bottom plate 77; a movable screen plate 74 is hinged to one side face of the bottom of the experiment cylinder 75, and a vertical loading unit 6 is arranged at the top end of an inner cavity of the experiment cylinder 75; a transverse push rod 76 is fixedly connected to the side wall of the experiment cylinder 75; one end of the transverse push rod 76 is detachably connected to the drive detection unit 8.
Further, a cathode connecting member 78 is preferably welded to the side of the base plate 72 for connection to the cathode electrode.
Further, pile foundation simulation bottom plate 77 is the metal iron material, simultaneously, can replace with different material simulation pile foundation surfaces in concrete experiment.
Further, the bottom surface of the experimental cylinder 75 is provided with a movable sealing screen plate 74, the movable sealing screen plate 74 is a sealing screen structure with the thickness of 1cm, the movable sealing screen plate is used for draining water at a cathode electrode when the experimental cylinder is powered on, the corresponding movable sealing screen plate 74 is covered on the bottom surface of the experimental cylinder 75 after the power is off, and for convenience of operation, one side of the experimental cylinder 75 and one side of the movable sealing screen plate 74 are hinged through a movable hinge piece.
Furthermore, in order to facilitate the experiment, a cross mark is arranged at the center of the bottom surface of the inner cavity of the base 71, so that the bottom plate 72 and the movable screen plate 74 can be placed accurately.
In a further optimized scheme, the vertical loading unit 6 comprises a bracket assembly, a vertical hydraulic cylinder 61, a first pressure sensor 62 and a material pressing assembly 68; a vertical hydraulic cylinder 61 is vertically and fixedly connected to the center of the bracket assembly; the bottom end of the hydraulic rod of the vertical hydraulic cylinder 61 is fixedly connected with the first pressure sensor 62; the bottom surface of the first pressure sensor 62 is fixedly connected with the pressing component 68; the first pressure sensor 62 is electrically connected with the data collector 2; vertical hydraulic cylinder 61 is connected with hydraulic loading system 1 transmission, can realize when vertical hydraulic cylinder 61 applys load to test mechanism 7, and first pressure sensor 62 can be saved for data collection appearance 2 with pressure data transmission.
In a further optimized scheme, the bracket assembly comprises two fixing plates 63; the two fixing plates 63 are arranged oppositely and fixedly connected through a plurality of stand columns 67; a through hole is formed in the center of the fixing plate 63; the inner wall of the via hole is fixedly connected with the fixed end of the vertical hydraulic cylinder 61; the opposite two side surfaces of the fixed plate 63 are fixedly connected with a T-shaped core 65 through a plurality of connecting rods 64 respectively; the end of the T-shaped core 65 remote from the connecting rod 64 is fitted slidingly with a guide 66; the bottom surface of the guide rail 66 is fixedly connected with the top surface of the box body 5.
Further, the guide rail 66 is a linear guide rail provided with a T-shaped groove, the T-shaped groove is matched with the T-shaped core 65, so that when the T-shaped core 65 slides in the T-shaped groove, the whole support assembly can be driven to move, and the material pressing assembly 68 can find the force application position conveniently.
In a further optimized scheme, the swaging assembly 68 comprises anti-slip claws 681; the top end of the anti-skid claw 681 is fixedly connected with the bottom surface of the first pressure sensor 62, and the bottom end of the anti-skid claw 681 is detachably connected with a top cover 682; a porous resistance plate 683 is fixedly connected with the bottom surface of the top cover 682; the graphite net 684 is fixedly connected with the bottom surface of the porous resistance plate 683; the graphite mesh 684 is electrically connected to an anode electrode (not shown in the drawings); the anode is electrically connected with the voltage regulating system 3; the top cap 682, porous resistance plate 683 and graphite mesh 684 are fitted into and in sliding contact with the test cartridge 75, respectively.
Further, a concave hole is formed in the bottom surface of the anti-slip claw 681; the top end of top cap 682 is provided with arch 685, and arch 685 and shrinkage pool looks adaptation have realized that when antiskid claw 681 exerted pressure downwards, top cap 682 can not take place the skew because of the atress inequality.
Further, the external dimensions of the top cover 682, the porous resistance plate 683 and the graphite mesh 684 are all consistent, and the external side surface of the top cover 682, the external side surface of the porous resistance plate 683 and the external side surface of the graphite mesh 684 are respectively matched with the experimental cylinder 75 and in sliding contact with the experimental cylinder 75, so that further operation on a sample in the experimental cylinder 75 is realized; the soil cake is arranged between the bottom surface of the graphite net 684 and the top surface of the movable dense mesh plate 74 and is arranged in the inner cavity of the experimental cylinder 75.
In a further optimized scheme, the driving detection unit 8 comprises a displacement sensor 81, a flat-load hydraulic cylinder 82 and a second pressure sensor 83; the flat-load hydraulic cylinder 82 is fixedly connected with the bottom surface of the inner cavity of the box body 5 through a strut 84; the flat-load hydraulic cylinder 82 is in transmission connection with the hydraulic loading system 1; the hydraulic rod of the flat-load hydraulic cylinder 82 is fixedly connected with a second pressure sensor 83; the displacement sensor 81 and the second pressure sensor 83 are respectively arranged at two sides of the experiment cylinder 75; the displacement sensor 81 is arranged opposite to the second pressure sensor 83; the displacement sensor 81 is fixedly connected with the inner side wall of the box body 5; one end surface of the transverse push rod 76 is arranged opposite to the second pressure sensor 83; the displacement sensor 81 and the second pressure sensor 83 are electrically connected to the data collector 2.
In a further optimized scheme, the middle part of the bottom surface of the transverse push rod 76 is provided with a abdicating groove; the abdicating groove is in clearance fit with the side wall of the experiment tube 75, so that when the transverse push rod 76 moves under the pushing of the flat-load hydraulic cylinder 82, the interference with the side wall of the experiment tube 75 can be avoided.
In a further optimized scheme, the top cover 682 and the bottom plate 72 are made of brass; the area of the top surface of the bottom plate 72 is larger than that of the bottom surface of the experiment cylinder 75; the bottom plate 72 is provided with two parallel convex ribs; the area of the pile foundation simulation bottom plate 77 is consistent with that of the bottom plate 72, and the bottom surface of the pile foundation simulation bottom plate 77 is provided with two grooves matched with the two parallel convex ribs on the bottom plate 72, so that the mutual movement of the two grooves is avoided. The top surface of the pile foundation simulation bottom plate 77 is a plane and is attached to the bottom surface of the experimental cylinder 75; a cathode connecting piece 78 is fixedly connected to the side surface of the bottom plate 72; the pile foundation simulation bottom plate 77 is used for simulating the surface of a single pile foundation of offshore wind power, the material adopted in the invention is low-carbon steel material, and pile foundation simulation bottom plate components made of various pile foundation simulation materials can be used for replacement so as to simulate the surfaces of pile foundations made of various materials in actual use.
In a further optimized scheme, the experimental cylinder 75 is made of high-resistance high-strength epoxy resin.
The first experimental mode of this embodiment:
the preparation method comprises the steps of firstly preparing a soil body, and immersing the soil body in seawater with different concentrations until pores are saturated according to test requirements;
the cartridge 75 and the movable screen plate 74 are moved to the center of the bottom plate 72 until the cross mark at the center of the bottom plate 72 is covered.
The finished soil sample was removed, and a cake of 20mm thickness was cut out using a cutting ring for testing, and the cake was pushed into a test tube 75.
The graphite mesh 684 and the porous resistance plate 683 are placed in sequence on the soil cake in the shear box, and then the brass cap 682 is placed over the porous resistance plate 683.
The cathode was firmly connected to the brass base plate 72 and the negative electrode of the power supply 4, respectively.
The positive electrode was confirmed to be firmly connected to the graphite mesh 684 in the cartridge 75 and the positive electrode of the power supply 4, respectively, and the switch of the power supply box was turned on.
After a period of time, after electroosmosis is completed, the hydraulic loading system 1 is opened, the vertical hydraulic cylinder 61 is controlled to perform vertical loading, the anti-skid claws 681 fixedly connected to the hydraulic rod of the vertical hydraulic cylinder 61 are buckled with the protrusions 685 on the top surface of the top cover 682, and then loading is performed.
Then, the horizontal loading is performed by controlling the horizontal loading hydraulic cylinder 82, and the second pressure sensor 83 fixed to the hydraulic rod of the horizontal loading hydraulic cylinder 82 is abutted against one end of the horizontal push rod 76, and then the loading is performed.
When the displacement of the experimental cylinder 75 is observed, the power supply 4 is switched on to supply power to the cathode electrode and the anode electrode so as to carry out electroosmotic reaction;
after the test is completed, the data on the data collector 2 is recorded and calculated and analyzed.
In addition, a control group test can be carried out, and the seawater concentration, the vertical loading force and the voltage of the power supply 4 during soil body preparation are adjusted;
in the teaching demonstration process, the movable screen plate 74 can be turned to be attached to the top surface of the pile foundation simulation base plate 77, and the electroosmosis reaction process can be visually displayed.
Experiment mode two in this example:
as a teaching process, firstly preparing a soil body, selecting three parts of the same soil body, immersing the three parts of the same soil body in saline water with the same concentration until pores are saturated, and pressing out water;
when the soil body is immersed, the test mechanism is arranged, firstly, a pile foundation simulation bottom plate 77 made of low-carbon steel material is selected, the bottom surface groove is aligned to the convex rib on the top surface of the bottom plate 72, after the bottom surface groove is mutually embedded and completely overlapped, the pile foundation simulation bottom plate is arranged on the base 71 until the cross mark on the base 71 is covered, and one side of the cathode connecting piece 78 is rightwards, so that the connection distance of an electric wire is reduced, and the test safety is ensured;
placing the experimental cylinder 75 at the center of the top surface of the pile foundation simulation bottom plate 77, taking out soil, cutting soil cakes with the thickness of 20mm by using a cutting ring, placing one soil cake into the experimental cylinder 75, and placing the other two soil cakes in a shade place for later use;
sequentially placing a graphite net 684 and a porous resistance plate 683 on a soil cake in the experiment cylinder 75, and covering a top cover 682 of brass on the porous resistance plate 683;
buckling an anti-skidding claw 681 fixedly connected to the vertical hydraulic cylinder 61 with a bump 685 on the top surface of the top cover 682;
a second pressure sensor 83 fixedly connected with a hydraulic rod of the flat-load hydraulic cylinder 82 is abutted against one section of the transverse push rod 76;
confirming that the cathode electrode is firmly connected with the cathode connecting piece and the negative electrode of the power supply 4 respectively;
confirming that the anode electrode is respectively and firmly connected with the graphite net 684 in the experimental cylinder 75 and the anode of the power supply 4;
loading the vertical hydraulic cylinder according to 200kpa, and simultaneously loading the horizontal hydraulic cylinder 82;
observing the data collector 2, gradually increasing the loading value of the horizontal hydraulic cylinder 82 when the horizontal displacement data is not changed, observing after each adjustment, continuously increasing if no displacement occurs, and recording data when displacement occurs until more than half of the experimental cylinder 75 and soil body are separated from the pile foundation simulation bottom plate 77 at the bottom;
after the data are recorded and sorted, the power supply 4 is switched off, the experiment cylinder 75 is taken out, the soil body in the experiment cylinder 75 is poured out, the experiment cylinder 75 and the pile foundation simulation base plate 77 are cleaned, and the surface is wiped dry;
otherwise, taking out the soil body to be used, preparing the soil body by using a cutting ring, cutting the soil body with the thickness of 20mm, and placing the soil body in the experiment cylinder 75;
during loading, simultaneously turning on the power supply 4 to supply power to the cathode electrode and the anode electrode, setting the voltage to be 20V through the voltage regulating system 3, carrying out the same vertical loading and horizontal loading, and observing data of the data recorder until the experimental cylinder 75 and the soil body are separated from the bottom pile foundation simulation bottom plate 77 by more than half;
after the second group of data is recorded and collated, the power supply 4 is switched off, the movable screen plate 74 at the lower part of the experimental cylinder 75 is opened, the characteristics of the soil body after electroosmosis reaction are observed, then the experimental cylinder 75 is taken out, the soil body in the experimental cylinder 75 is poured out, the experimental cylinder 75 and the pile foundation simulation bottom plate 77 are cleaned, and the surface is wiped dry;
the other operations are the same as the above, the third part of soil body to be used is taken out and prepared by a cutting ring, the soil body with the thickness of 20mm is cut out and placed in the experiment cylinder 75;
during loading, the voltage is set to be 40V through the voltage regulating system 3, the vertical loading and the horizontal loading are carried out in the same way, and the data of the data recorder are observed until more than half of the experimental cylinder 75 and the soil body are separated from the bottom pile foundation simulation bottom plate 77;
similarly, the voltage is positioned at 80V by the voltage regulating system 3, the experiment is repeated again, and after the third group of data is recorded and collated, the three groups of data can be compared, and the mechanism of reducing pile-soil friction by electroosmosis, particularly the influence of voltage, can be researched.
Example two
The embodiment is subjected to simulation operation according to actual engineering conditions, so that the optimal voltage reference and guidance opinions in actual engineering can be explored.
According to the pile foundation condition of the actual engineering, the pile foundation simulation bottom plate 77 made of the corresponding material is selected, and further, the impact simulation bottom plate 77 can be subjected to relevant treatment according to specific conditions;
calculating the corresponding pile foundation surface pressure according to the sea water depth and the seabed soil quality of the pile foundation embedding of the actual engineering, recording, and selecting consistent loading pressure during vertical loading;
preparing or obtaining a soil sample the same as the surface of the pile foundation according to the exploration condition of the actual engineering;
cutting a soil sample into a soil body with the thickness of 20mm by using a cutting ring, and placing the rest soil sample in a shade place for later use;
the experimental device is arranged and checked while the soil body is prepared, firstly, a pile foundation simulation bottom plate 77 made of the same material as the pile foundation is selected, grooves in the bottom surface of the pile foundation simulation bottom plate 77 are aligned to the convex ribs on the top surface of the bottom plate 72, the pile foundation simulation bottom plate 77 is arranged on the base 71 after being mutually embedded and completely overlapped until the cross marks on the base 71 are covered, and one side of the cathode connecting piece 78 is rightwards, so that the electric wire connecting distance is reduced, and the test safety is ensured;
sequentially placing the graphite net 684 and the porous resistance plate 683 on the soil cake in the experimental cylinder 75, and covering the brass top cap 682 on the porous resistance plate 683;
buckling an anti-skidding claw 681 fixedly connected to the vertical hydraulic cylinder 61 with a bump 685 on the top surface of the top cover 682;
a second pressure sensor 83 fixedly connected on a hydraulic rod of the flat-loading hydraulic cylinder 82 is abutted against one section of the transverse push rod 76;
confirming that the cathode electrode is firmly connected with the cathode connecting piece and the cathode of the power supply 4 respectively;
confirming that the anode electrode is respectively and firmly connected with the graphite net 684 in the experimental cylinder 75 and the positive electrode of the power supply 4;
loading the vertical load according to the calculated condition, observing the data collector 2, gradually increasing the loading value of the horizontal load hydraulic cylinder 82 when the horizontal displacement data is not changed, observing after each adjustment, continuing increasing if no displacement occurs, and recording data when displacement occurs until the experimental cylinder 75 and the soil body are separated from the bottom pile foundation simulation bottom plate 77 by more than half;
after the data are recorded and sorted, the power supply 4 is switched off, the experiment cylinder 75 is taken out, the soil body in the experiment cylinder 75 is poured out, the experiment cylinder 75 and the pile foundation simulation base plate 77 are cleaned, and the surface is wiped dry; the other operations are the same as the above, the soil sample to be used is taken out and prepared by a cutting ring, a soil body with the thickness of 20mm is cut out and placed in the experimental cylinder 75;
during loading, the power supply 4 is simultaneously turned on to supply power to the cathode electrode and the anode electrode, the voltage is set to be 20V through the voltage regulating system 3, the vertical loading and the horizontal loading are carried out in the same way, and the data of the data collector 2 are observed until the experimental cylinder 75 and the soil body exceed the pile foundation simulation bottom plate 77 which is generally separated from the bottom;
and recording and collecting data, repeating the experiment operation, performing experiments at 40V, 80V, 160V and 320V respectively, finding an optimum voltage interval, performing voltage subdivision experiments, and finally providing voltage selection reference and guidance suggestions for specific operation for specific engineering.
In the description of the present invention, it is to be understood that the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on those shown in the drawings, and are used merely for convenience in describing the present invention, and do not indicate or imply that the device or element so referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.
The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.
Claims (8)
1. The utility model provides a simulation electroosmosis reduces test device of stake-soil friction mechanism, includes hydraulic pressure loading system (1), data collection appearance (2), voltage control system (3), power (4) and with box (5) and the shear test device of above-mentioned part looks adaptation, its characterized in that: the hydraulic loading system (1), the data collector (2), the voltage regulating system (3) and the power supply (4) are arranged at one end of an inner cavity of the box body (5), and the rest part of the inner cavity of the box body (5) is provided with the shear test device; a vertical loading unit (6) is fixedly connected to the top surface of the box body (5); the shear test device comprises a test mechanism (7) for carrying out simulation experiments on samples and a driving detection unit (8) for giving load force to the test mechanism (7); the driving detection units (8) are arranged on two opposite sides of the test mechanism (7); the driving detection unit (8) is fixedly connected with the box body (5);
the hydraulic loading system (1) is in transmission connection with the driving detection unit (8) and the vertical loading unit (6) respectively; the voltage regulating system (3) is electrically connected with the testing mechanism (7); the power supply (4) is electrically connected with the hydraulic loading system (1), the data collector (2) and the voltage regulating system (3) respectively; the data collector (2) is electrically connected with the vertical loading unit (6) and the driving detection unit (8) respectively;
the testing mechanism (7) comprises a base (71); the base (71) is of a box-shaped structure with an open top surface; a bottom plate (72) is arranged at the center of the bottom surface of the inner cavity of the base (71); a cathode connecting piece (78) is fixedly connected to the bottom plate (72), and the cathode connecting piece (78) is electrically connected with a cathode electrode; the cathode electrode is electrically connected with the voltage regulating system (3); a pile foundation simulation bottom plate (77) is placed on the top surface of the bottom plate (72); an experimental cylinder (75) is arranged on the top surface of the pile foundation simulation bottom plate (77); a movable sealing screen plate (74) is hinged to one side face of the bottom of the experiment cylinder (75), and the vertical loading unit (6) is arranged at the top end of the inner cavity of the experiment cylinder (75); a transverse push rod (76) is fixedly connected to the side wall of the experiment cylinder (75); one end of the transverse push rod (76) is detachably connected with the driving detection unit (8);
the vertical loading unit (6) comprises a bracket assembly, a vertical hydraulic cylinder (61), a first pressure sensor (62) and a material pressing assembly (68); the center of the bracket component is vertically fixedly connected with the vertical hydraulic cylinder (61); the bottom end of a hydraulic rod of the vertical hydraulic cylinder (61) is fixedly connected with the first pressure sensor (62); the bottom surface of the first pressure sensor (62) is fixedly connected with the pressing component (68); the first pressure sensor (62) is electrically connected with the data collector (2); the vertical hydraulic cylinder (61) is in transmission connection with the hydraulic loading system (1).
2. A device according to claim 1 for simulating an electroosmosis pile-soil friction mechanism, wherein: the bracket assembly comprises two fixing plates (63); the two fixing plates (63) are arranged oppositely and fixedly connected through a plurality of stand columns (67); a through hole is formed in the center of the fixing plate (63); the vertical hydraulic cylinder (61) is fixedly arranged in the through hole; the opposite two side surfaces of the fixed plate (63) are fixedly connected with a T-shaped core (65) through a plurality of connecting rods (64); one end of the T-shaped core (65) far away from the connecting rod (64) is matched with a guide rail (66) in a sliding way; the bottom surface of the guide rail (66) is fixedly connected with the top surface of the box body (5).
3. A device according to claim 2 for simulating an electroosmosis pile-soil friction mechanism, wherein: the swaging assembly (68) includes a slip-resistant jaw (681); the top end of the anti-skid claw (681) is fixedly connected with the bottom surface of the first pressure sensor (62), and the bottom end of the anti-skid claw (681) is detachably connected with a top cover (682); a porous resistance plate (683) is fixedly connected to the bottom surface of the top cover (682); the bottom surface of the porous resistance plate (683) is fixedly connected with a graphite net (684); the graphite net (684) is electrically connected with an anode electrode; the anode is electrically connected with the voltage regulating system (3); the top cap (682), the porous resistance plate (683) and the graphite mesh (684) are respectively fitted into and in sliding contact with the test cartridge (75).
4. A device according to claim 3 for simulating an electroosmosis pile-soil friction mechanism, wherein: the driving detection unit (8) comprises a displacement sensor (81), a horizontal load hydraulic cylinder (82) and a second pressure sensor (83); the flat-load hydraulic cylinder (82) is fixedly connected with the bottom surface of the inner cavity of the box body (5) through a strut (84); the flat-load hydraulic cylinder (82) is in transmission connection with the hydraulic loading system (1); a hydraulic rod of the horizontal load hydraulic cylinder (82) is fixedly connected with the second pressure sensor (83); the displacement sensor (81) and the second pressure sensor (83) are respectively arranged on two sides of the experiment cylinder (75); the displacement sensor (81) is arranged opposite to the second pressure sensor (83); the displacement sensor (81) is fixedly connected with the inner side wall of the box body (5); one end face of the transverse push rod (76) is arranged opposite to the second pressure sensor (83); the displacement sensor (81) and the second pressure sensor (83) are respectively electrically connected with the data collector (2).
5. The device of claim 4, wherein the device comprises: one end of the inner cavity of the box body (5) is divided into an experimental cavity and four independent placing cavities by a plurality of partition plates; the hydraulic loading system (1), the data collector (2), the voltage regulating system (3) and the power supply (4) are respectively arranged in the four placing cavities; the base (71) and the support column (84) are arranged on the bottom surface of the experiment cavity.
6. A device according to claim 1 for simulating an electroosmosis pile-soil friction mechanism, wherein: the middle part of the bottom surface of the transverse push rod (76) is provided with a abdicating groove; the abdicating groove is in clearance fit with the side wall of the experimental cylinder (75).
7. A device according to claim 3, wherein the device is adapted to simulate an electroosmosis-induced pile-soil friction mechanism, wherein: the top cover (682) and the bottom plate (72) are made of brass; the area of the top surface of the bottom plate (72) is larger than that of the bottom surface of the experiment cylinder (75); the bottom plate (72) is provided with two parallel convex ribs; the area of the pile foundation simulation base plate (77) is consistent with that of the base plate (72), and two grooves matched with the two parallel convex ribs on the base plate (72) are formed in the bottom surface of the pile foundation simulation base plate (77).
8. The device of claim 1, wherein the device comprises: the experimental cylinder (75) is made of high-resistance and high-strength epoxy resin.
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| CN202210429903.6A CN114813375B (en) | 2022-04-22 | 2022-04-22 | Test device for simulating electroosmosis to reduce pile-soil friction mechanism |
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| US6615653B1 (en) * | 2001-09-27 | 2003-09-09 | Geosierra, Llc | In situ method for determining soil liquefaction tendency and its prevention by electro-osmosis |
| CN102393404B (en) * | 2011-09-15 | 2012-12-26 | 温州大学 | Large model test box for studying electroosmosis consolidation treated soft soil foundation |
| CN202421109U (en) * | 2012-01-11 | 2012-09-05 | 清华大学 | Vacuum and electro-osmosis united consolidometer |
| CN102721616B (en) * | 2012-02-16 | 2014-07-09 | 中交天津港湾工程研究院有限公司 | Electroosmosis shear apparatus |
| CN103278402A (en) * | 2013-05-23 | 2013-09-04 | 广西壮族自治区交通规划勘察设计研究院 | Electro-osmosis consolidation shearing device |
| CN104805823B (en) * | 2015-01-05 | 2017-03-22 | 温州大学 | Large-scale model test device for supercharged vacuum prepressing and electro-osmosis combined treatment for soft soil foundation |
| CN105547864B (en) * | 2016-01-22 | 2018-07-27 | 武汉轻工大学 | The assay method and dedicated full-automatic direct shear apparatus of chemical contamination shear strength of soil |
| CN106053254A (en) * | 2016-07-07 | 2016-10-26 | 天津城建大学 | Electric osmosis-loading joint shear apparatus |
| CN108760601B (en) * | 2018-05-22 | 2019-10-11 | 青岛理工大学 | Test device for simulating freeze-thaw cycle and rapidly testing soil strength and permeability coefficient |
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