CN113607633A - Device and method for measuring resistance reduction performance of pipe jacking slurry sleeve under condition of axisymmetric stress - Google Patents
Device and method for measuring resistance reduction performance of pipe jacking slurry sleeve under condition of axisymmetric stress Download PDFInfo
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- CN113607633A CN113607633A CN202110840090.5A CN202110840090A CN113607633A CN 113607633 A CN113607633 A CN 113607633A CN 202110840090 A CN202110840090 A CN 202110840090A CN 113607633 A CN113607633 A CN 113607633A
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- 239000002002 slurry Substances 0.000 title claims abstract description 70
- 238000000034 method Methods 0.000 title claims abstract description 30
- 230000009467 reduction Effects 0.000 title claims description 18
- 238000012360 testing method Methods 0.000 claims abstract description 51
- 239000011435 rock Substances 0.000 claims abstract description 41
- 238000002360 preparation method Methods 0.000 claims abstract description 25
- 238000007906 compression Methods 0.000 claims abstract description 23
- 230000006835 compression Effects 0.000 claims abstract description 20
- 230000008569 process Effects 0.000 claims abstract description 20
- 230000001603 reducing effect Effects 0.000 claims abstract description 14
- 239000002689 soil Substances 0.000 claims description 35
- 230000009974 thixotropic effect Effects 0.000 claims description 21
- 238000007789 sealing Methods 0.000 claims description 16
- 230000009471 action Effects 0.000 claims description 8
- 239000012528 membrane Substances 0.000 claims description 8
- 238000003756 stirring Methods 0.000 claims description 6
- 239000013589 supplement Substances 0.000 claims description 6
- 230000001502 supplementing effect Effects 0.000 claims description 5
- 239000012466 permeate Substances 0.000 claims description 4
- 230000015572 biosynthetic process Effects 0.000 claims description 3
- 230000008595 infiltration Effects 0.000 claims description 3
- 238000001764 infiltration Methods 0.000 claims description 3
- 239000000314 lubricant Substances 0.000 claims description 3
- 238000004088 simulation Methods 0.000 abstract description 4
- 238000010276 construction Methods 0.000 description 7
- 238000007569 slipcasting Methods 0.000 description 7
- 230000000694 effects Effects 0.000 description 5
- 229910000831 Steel Inorganic materials 0.000 description 3
- 230000001276 controlling effect Effects 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 238000006073 displacement reaction Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 239000011440 grout Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910000278 bentonite Inorganic materials 0.000 description 1
- 239000000440 bentonite Substances 0.000 description 1
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 description 1
- 230000003139 buffering effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 230000035699 permeability Effects 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
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
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Abstract
The invention discloses a pipe jacking slurry sleeve resistance reducing performance measuring device under an axial symmetric stress condition, which comprises a double-column type tension and compression testing machine and a pressure chamber arranged in the double-column type tension and compression testing machine, wherein a cylindrical space for placing a concrete column is vertically arranged in the middle of the pressure chamber, a built-in bolt is arranged at the upper part of the concrete column, the built-in bolt is connected with one end of a tensile joint, the other end of the tensile joint is connected with a cross beam of the double-column type tension and compression testing machine, a surrounding rock model preparation chamber and a grouting channel which are communicated are arranged in the pressure chamber at the periphery of the cylindrical space, the upper end of the pressure chamber is connected with an air pressure booster through an air pressure joint, the upper end of the grouting channel is connected with a grouting system through a grouting joint, the grouting system performs grouting to the grouting channel, realizes simulation of pipe jacking grouting resistance reducing and real-time grouting process, and a data acquisition and control system is used for collecting the double-column type tension and compression testing machine, the pressure data of the grouting system and the air pressure booster controls the operation of the whole device. Also disclosed are methods of determination. The invention has reasonable design and simple operation.
Description
Technical Field
The invention relates to a pipe jacking test device and a measurement method, in particular to a pipe jacking slurry sleeve resistance reduction performance measurement device and a method under an axisymmetric stress condition.
Background
In the pipe jacking construction, a tool pipe or a heading machine passes through a soil layer along the line from a working well to enter a receiving well by means of the thrust of jacking equipment such as a main oil jacking pump; and simultaneously, connecting the pipelines which are next to the underground pipelines in sequence and burying the pipelines into the pipeline soil layers of the two wells. With the scientific and technological progress and the rapid development of economy in China and the enhancement of environmental awareness, the pipe jacking construction technology is accepted by the engineering community as a conventional construction method. Because the pipe jacking method is safe in construction, has no influence or little influence on the surrounding environment, and is widely applied to various application occasions such as municipal tunnels, water supply and drainage pipelines, oil and gas pipelines, comprehensive pipe galleries and the like.
In jacking of the jacking pipe, the friction force borne by the pipeline along the line is increased along with the increase of the jacking length, and under the condition that the positive pressure is not changed, the friction coefficient is the main influence factor, so the value of the friction coefficient is reduced when the friction force is reduced. Therefore, in the construction process, thixotropic slurry is injected to the outer surface of the pipeline, and the friction coefficient is reduced by using the thixotropic slurry. The basic components of a thixotropic slurry are bentonite and water. When the amount of the mud between the pipeline and the surrounding rock is enough and the water loss amount is small, a layer of thin and compact mud skin can be formed on the soil wall, the soil wall can be protected and the mud loss can be prevented, and the complete mud skin is wrapped on the outer surface of the pipeline, namely the mud sleeve.
In the existing pipe jacking model device, the overburden pressure can be simulated only by applying unidirectional load to a pipeline, and the real surrounding rock pressure cannot be simulated; the existing model device only considers the initial grouting of the pipeline, but does not fully consider the influence of the actual grouting pressure and the real-time slurry supplement after the second section and the second section of jacking pipe on the friction reduction and drag reduction performance of the slurry sleeve, and the friction resistance and the friction coefficient in the jacking process of the pipeline cannot be accurately tested due to certain difference from the actual construction.
Chinese patent application CN 102636430a discloses an indoor simulation experiment system for pipe-jacking grouting drag reduction, which comprises a test box, a vertical loading test system, a horizontal loading test system, a pipeline to be tested, a grouting conduit and a grouting system. The technology of the patent can simulate the overburden pressure, can realize the simulation of grouting drag reduction, measures the friction force and the friction coefficient in the pipe jacking process, and still has the following problems: 1) the physical model test adopts the pressure of the surrounding rock of the jacking pipe under the condition of side limit (horizontal displacement is 0) of the box body, which is different from the actual soil body pressure and deformation, and the flexible boundary condition of controllable axisymmetric stress is adopted in the invention, which is more close to the actual soil body pressure and deformation; 2) the real-time slurry replenishing process of subsequent pipe joints in actual pipe jacking engineering is not considered, the friction reducing and drag reducing effects of slurry sleeve pipe jacking are continuously measured, and the actual characteristic is considered.
Chinese patent application CN 112147313 a discloses a simulation test device for large-section rectangular pipe jacking antifriction grouting, comprising: the test soil box, the front pipe joint, the starting bracket, the rear pipe joint, the rear leaning frame and the pushing mechanism. This patent technique can simulate pipe jacking drag reduction slip casting test, can not directly strike the soil body and can form the even mud cover of distribution during the slip casting, but still has two problems: 1) the physical model test adopts the pipe-jacking surrounding rock pressure under the condition of box body lateral limit (horizontal displacement is 0), in the actual pipe-jacking engineering, a pipeline is under the pressure of a surrounding rock soil body, under the surrounding pressure, mud has stronger permeability in the soil body, a compact permeable block is formed, and the deformation of the soil body around the pipe is influenced, and the flexible boundary condition of controllable axisymmetric stress is adopted in the invention, so that the pressure and the deformation of the actual soil body are more approximate; 2) the patent does not consider overlying soil pressure, and the grouting pressure is closely related to the overlying soil pressure, and the grouting pressure influences the soil deformation effect and is a control factor of the thickness of the mud sleeve.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a device and a method for measuring the resistance reduction performance of a pipe jacking slurry sleeve under the condition of axial symmetric stress.
In order to achieve the purpose, the invention adopts the following technical scheme:
a pipe jacking slurry sleeve resistance reducing performance measuring device under an axial symmetric stress condition comprises a double-column type tension and compression testing machine and a pressure chamber arranged in the double-column type tension and compression testing machine, wherein a cylindrical space used for placing a concrete column is vertically arranged in the middle of the pressure chamber, a built-in bolt is arranged at the upper part of the concrete column and is connected with one end of a tensile joint, the other end of the tensile joint is connected with a cross beam of the double-column type tension and compression testing machine, the concrete column is pushed and pulled back and forth in the vertical direction by utilizing the reciprocating motion of the cross beam, a surrounding rock model preparation chamber and a grouting channel which are communicated are arranged in the pressure chamber at the periphery of the cylindrical space, the upper end of the pressure chamber is connected with an air pressure booster through an air pressure joint, the pressure is boosted in the pressure chamber through conveying air, the upper end of the grouting channel is connected with a grouting system through the grouting joint, the grouting system performs grouting to the grouting channel, the preparation of the surrounding rock model is realized, and the real-time grouting can be performed in the subsequent jacking process, the data acquisition and control system is used for collecting pressure data of the double-column type tension and compression testing machine, the grouting system and the air pressure booster and controlling the operation of the whole set of device.
The pressure chamber comprises a cylindrical shell, an upper disc, a base and a lower sealing disc, the upper end and the lower end of the cylindrical shell are respectively clamped in annular grooves in the bottom of the upper disc and the upper surface of the base, the lower sealing disc is fixedly connected to the center of the bottom of the base, the peripheries of the upper disc and the base are fixedly connected through a plurality of connecting pieces, a grouting disc is fixed on the upper disc, a grouting joint communicated with a grouting channel is arranged on the grouting disc, the centers of the grouting disc, the upper disc, the base and the lower sealing disc are provided with concentric cylindrical spaces, the grouting channel is tightly attached to the peripheries of the cylindrical spaces, the peripheries of the grouting channels are surrounding rock model preparation chambers, and air pressure joints communicated with the surrounding rock model preparation chambers are further arranged on the upper disc.
The diameter of the cylindrical space positioned in the center of the grouting disc, the upper disc and the base is equal to the diameter of the concrete column to be measured.
And a lubricant is coated on the contact surface of the upper disc and the concrete column.
The top and the bottom of the surrounding rock model preparation chamber are respectively provided with a sample cover and a sample base, the inner surface of the surrounding rock model preparation chamber is provided with a rubber film, the lower end of the rubber film is fixed through the sample base, and the upper end of the rubber film is inserted into the sample cover and the model soil.
O-shaped rings are arranged on the contact surfaces of the grouting disc and the concrete column and the contact surfaces of the base and the concrete column; rubber pads are arranged in the annular grooves at the contact positions of the upper disc, the base and the two ends of the cylindrical shell.
The lower sealing disc is a cylinder with an I-shaped longitudinal section, the diameter of the cylindrical space at the center is larger than that of the concrete column, the lower sealing disc is not in direct contact with the concrete column, and a certain gap is reserved, so that the influence of other friction forces on the test precision can be reduced, the friction force measured in the jacking process can be generated under the action of the concrete column and thixotropic slurry (soil body), and the test error is reduced.
The pressure chamber is a cylindrical pressure chamber, and is pressurized through an air pressure joint arranged on the upper disc, so that axisymmetric stress can be formed to act on the surrounding rock model preparation chamber.
The concrete column is a solid concrete column, steel bars are buried in the concrete column during pouring, and a built-in bolt is arranged at the upper part of the concrete column.
The double-column type tension and compression testing machine pushes and pulls the concrete column through the up-and-down reciprocating movement of the cross beam, so that the concrete column moves at a constant speed, the influence of the gravity and other resistance of the concrete column is eliminated, and the frictional resistance in the jacking process is obtained.
Slip casting system includes atmospheric pressure booster compressor, manometer, slip casting jar and mud agitated vessel, wherein: the size of the grouting tank is designed according to the concrete column ratio of 1:1, the top of the grouting tank is connected with a pressure gauge through a pressure gauge joint respectively, the grouting tank is connected with an air pressure booster through an air pressure joint and is used for detecting and controlling grouting pressure respectively, and the bottom of the grouting tank is used for grouting into a grouting channel through a grouting joint and performing real-time grouting supplement in the subsequent jacking process. After being stirred by slurry stirring equipment, the thixotropic slurry is placed in a grouting tank, and screw caps are arranged on two sides of the upper part of the grouting tank, so that the thixotropic slurry is convenient to load and pour.
The grouting tank comprises a cylindrical tank body and end caps at the upper end and the lower end, the bottom of the cylindrical tank body is tightly connected with the end cap at the lower end, the end cap at the top is screwed at the upper end of the cylindrical tank body through a screw cap, and an O-shaped ring is arranged between the cylindrical tank body and the end cap at the upper end.
The data acquisition and control system comprises pressure sensor, atmospheric pressure booster compressor, manometer and well accuse unit, wherein: be equipped with the manometer between atmospheric pressure booster compressor and the pressure chamber, be equipped with pressure sensor between crossbeam and the tensile joint, slip casting jar upper portion is equipped with the manometer, and the manometer all connects through the manometer joint, and simultaneously, manometer, pressure sensor and well accuse unit all connect on the computer through the wire.
The method for measuring the resistance reduction performance of the pipe-jacking slurry sleeve under the condition of axisymmetric stress comprises the following steps:
1) before a test, connecting all parts of a grouting system and a data acquisition and control system, and connecting the grouting system and the data acquisition and control system with a pressure chamber, wherein a surrounding rock model preparation chamber in the pressure chamber needs to be filled with a model soil body and compacted in layers according to requirements;
2) performing a pre-test, connecting a tensile joint of the double-column type tension and compression testing machine with a built-in bolt at the upper part of the concrete column under the condition that no axisymmetric stress is applied to the pressure chamber, and enabling the concrete column to move up and down in the pressure chamber by utilizing the up-and-down reciprocating motion of a cross beam;
3) when a test is started, firstly, thixotropic slurry is injected into a grouting channel in a pressure chamber through a grouting joint, an air pressure booster is opened after the thixotropic slurry is filled, air pressure is added into the pressure chamber to simulate real formation surrounding rock pressure, the formed axisymmetric stress uniformly acts on the thixotropic slurry in the grouting channel through a rubber film on the surface of a surrounding rock model preparation chamber, the slurry can permeate into surrounding soil to form a compact infiltration block under the action of the pressure, the air pressure booster is closed, and meanwhile, the air pressure joint is closed to prevent air pressure leakage;
4) continuing grouting, and repeating the step 3) until the grouting channel can be filled with the slurry under the applied axisymmetric stress condition;
5) starting a double-column type tension-compression testing machine, pushing a concrete column through the movement of a cross beam, simulating the jacking process of a pipeline, and when a second section of concrete column enters a pressure chamber, supplementing slurry to a grouting channel by using a grouting system until the last section of concrete column is jacked in, thereby really achieving real-time slurry supplement;
6) through the five steps, a real and complete push pipe slurry sleeve is formed, and the friction reducing and drag reducing mechanical property parameters of the slurry sleeve are measured under the coordination of a data acquisition and control system.
The invention has the beneficial effects that: the pressure chamber is utilized to apply axisymmetric stress to the concrete column so as to simulate the pressure of surrounding rocks in a real stratum acting on a pipeline, and meanwhile, the overlying soil pressure can be regulated and controlled, so that the grouting pressure of a model test is close to the real grouting pressure. When the mud on the surface of the pipeline permeates into the soil body, the soil body and the mud can form a layer of compact permeating blocks, and the deformation of the soil body around the pipeline is changed due to different mud permeating distances under the action of different surrounding rock pressures; the grouting pressure is closely related to the overlying soil pressure, the grouting pressure is increased by increasing the covering soil pressure, and the deformation degree of the peripheral hole wall of the pipe is different under the action of different grouting pressures, which is an important factor for controlling the thickness of the mud sleeve. The grouting system can perform grouting to the grouting channel at any time, and can realize real-time grout supplement when the second section and the concrete column behind the second section are jacked, so that a continuous and complete grout sleeve is formed around the subsequent concrete column as the front concrete column and is consistent with the pressure of the soil. Through the key parts, the surrounding rock pressure, the overburden soil pressure and the real-time slurry supplement effect of subsequent pipe joints in actual pipe jacking construction can be simulated to the maximum extent, a complete and real slurry sleeve is formed, and more accurate jacking force and friction force are obtained through testing.
Drawings
FIG. 1 is a schematic structural view of the present invention as a whole;
FIG. 2 is a schematic structural view of a pressure chamber according to the present invention;
FIG. 3 is a top view of FIG. 2;
FIG. 4 is a schematic structural diagram of the grouting tank of the invention;
wherein: 1. the device comprises a double-column type tension and compression testing machine, 11 a cross beam, 12 a pressure sensor, 2 a pressure chamber, 21 a rubber pad, 22 a surrounding rock model preparation chamber, 23 a grouting channel, 24 a grouting disc, 25 an upper disc, 26 a base, 27 a lower sealing disc, 28 a rubber film, 281 a sample base, 282 a sample cover, 3 an air pressure booster, 4 a pressure gauge, 41 a pressure gauge joint, 5 a central control unit, 6 a grouting tank, 61 a tank body, 62 a plug, 63. O-shaped rings, 64 a rotary cover, 65 an air pressure joint, 66 a grouting joint, 7 a concrete column, 71 built-in bolts, 72 a tensile joint, 8 a mud stirring device, 9 stud bolts, 91 bolts and 92 nuts.
Detailed Description
The invention is further illustrated with reference to the following figures and examples.
The structure, proportion, size and the like shown in the drawings are only used for matching with the content disclosed in the specification, so that the person skilled in the art can understand and read the description, and the description is not used for limiting the limit condition of the implementation of the invention, so the method has no technical essence, and any structural modification, proportion relation change or size adjustment still falls within the scope covered by the technical content disclosed by the invention without affecting the effect and the achievable purpose of the invention. In addition, the terms "upper", "lower", "left", "right", "middle" and "one" used in the present specification are for clarity of description, and are not intended to limit the scope of the present invention, and the relative relationship between the terms and the terms is not to be construed as a scope of the present invention.
As shown in figures 1-4, the device for testing the resistance reduction performance of the pipe jacking slurry sleeve under the condition of axial symmetric stress comprises a double-column type tension and compression testing machine 1, a pressure chamber 2, a grouting system and a data acquisition and control system, wherein a cylindrical space with a certain diameter is arranged in the middle of the pressure chamber 2, a concrete column 7 is arranged in the cylindrical space, the upper part of the concrete column 7 is provided with a built-in bolt 71, one end of a tensile joint 72 is connected with the built-in bolt 71, the other end is connected with a cross beam 11 of the double-column type tension and compression testing machine 1, the concrete column 7 is pushed and pulled in the vertical direction by utilizing the reciprocating motion of the cross beam 11, the upper end of a pressure chamber 2 is connected with an air pressure booster 3 through an air pressure joint 65, the upper end of a grouting channel 23 is connected with a grouting system through a grouting joint 66, the grouting system performs grouting on the grouting channel 23, and slurry can be supplemented in real time in the subsequent jacking process, and the data acquisition and control system mainly collects relevant pressure data and controls the operation of the whole device.
The concrete column 7 is a specially-made solid concrete column, steel bars are embedded in the concrete column during pouring, the upper portion of the concrete column is provided with a built-in bolt 71, when the built-in bolt 71 moves, the whole concrete column 7 is driven to move by the aid of the embedded steel bars, and the diameter of the concrete column 7 is equal to that of the cylindrical space.
When the double-column type tension and compression testing machine 1 drives the concrete column 7 to reciprocate, the acting force of pushing and pulling the concrete column 7 at each time is measured through the pressure sensor 12, the uniform motion of the concrete column is controlled, the interference of self gravity when the concrete column is vertically placed can be eliminated by utilizing two balance equations, and the friction reducing and drag reducing effects of the push pipe slurry sleeve can be accurately analyzed.
As shown in fig. 2 and 3, the pressure chamber 2 includes a rubber pad 21, a surrounding rock model preparation chamber 22, a grouting passage 23, a grouting disc 24, an upper disc 25, a base 26, a lower sealing disc 27, a rubber membrane 28, a sample base 281, and a sample cover 282, wherein: a grouting joint 66 is arranged on the grouting disc 24, thixotropic slurry flows into the grouting channel 23 through the upper disc 25, the stud 9 is arranged at the outer end of the pressure chamber 2, the upper part of the stud is connected with the upper disc 25, the lower part of the stud is connected with the base 26, the grouting disc 24 is connected with the upper disc 25 through a screw 91, the base 26 is connected with the lower sealing disc 27 through a screw 91, O-shaped rings 63 are arranged on the contact surfaces of the grouting disc 24, the base 26 and the concrete column 7, air pressure leakage when the pressure chamber 2 is pressurized is prevented, and rubber pads 21 are arranged at the contact positions of the upper disc 25, the base 26 and the two ends of the pressure chamber 2, so that buffering and sealing effects are achieved.
The inner surface of the surrounding rock model preparation chamber 22 is provided with a rubber membrane 28, the lower end of the rubber membrane 28 is fixed through a sample base 281, the upper end of the rubber membrane is inserted into a sample cover 282 and model soil, and the fixed rubber membrane 28 can uniformly apply air pressure in the pressure chamber 2 to the surrounding rock model, so that the surrounding rock pressure of the stratum can be truly simulated, and the concrete column 7 is subjected to the action of axisymmetric stress when being jacked.
The pressure chamber 2 is a cylindrical pressure chamber, axial symmetric stress can be formed to act on the surrounding rock model preparation chamber 22 by pressurizing the pressure chamber 2 through the air pressure joint 65 arranged on the upper disc 23, the problem that the existing pipe jacking model can only apply unidirectional load to simulate overlying soil pressure and can not simulate surrounding rock pressure applied in the jacking process of a pipeline is solved, and the confining pressure effect of the surrounding rock of the stratum on the concrete column 7 can be truly simulated.
The contact surface of the upper disc 25 and the concrete column 7 is coated with a lubricant, the lower sealing disc 27 is not in direct contact with the concrete column 7, and a certain gap is reserved, so that the influence of other friction forces on the test precision can be reduced, the friction force measured in the jacking process can be considered to be generated by the action of the concrete column 7 and thixotropic slurry (soil mass), and the test error is reduced.
As shown in fig. 4, the grouting system includes a pneumatic booster 3, a pressure gauge 4, a grouting tank 6 and a slurry stirring device 8, wherein: the size of the grouting tank 6 is designed according to the concrete column 7 in a ratio of 1:1, the upper part of the grouting tank 6 is connected with an air pressure booster 3 through an air pressure joint 65, the upper part of the grouting tank 6 is connected with a pressure gauge 4 through a pressure gauge joint 41, grouting pressure is applied and detected respectively, and grouting is performed on the lower part of the grouting tank through a grouting joint 66 to the grouting channel 23 and is supplemented in real time in the subsequent jacking process. Thixotropic slurry is stirred by a slurry stirring device 8 and then is placed in the grouting tank 6, and the two sides of the upper part of the grouting tank 6 are provided with screw caps 64, so that the slurry can be conveniently filled and poured out.
The grouting tank 6 comprises a cylindrical tank body 61 and end caps 62 at the upper end and the lower end, the bottom of the cylindrical tank body 61 is tightly connected with the end cap at the lower end, the end cap 62 at the top is screwed at the upper end of the cylindrical tank body 61 through a screw cover 64, and an O-shaped ring 63 is arranged between the cylindrical tank body 61 and the end cap 62 at the upper end for realizing the sealing of the device and preventing the leakage of thixotropic slurry.
The grouting channels 23 are arranged between the surrounding rock model preparation chamber 22 and the concrete columns 7 in a hollow cylindrical shape, a plurality of studs 9 are arranged at the periphery of the pressure chamber 2 at intervals and penetrate through the upper disc 25 and the base 26, and the upper disc 25 and the base 26 can be fixed at the upper end and the lower end of the pressure chamber 2 through nuts 92.
Data acquisition and control system comprises pressure sensor 12, atmospheric pressure booster compressor 3, manometer 4 and well central control unit 5, wherein: be equipped with manometer 4 between atmospheric pressure booster compressor 3 and the pressure chamber 2, be equipped with pressure sensor 12 between crossbeam 11 and the tensile joint 72, slip casting 6 upper portions are equipped with manometer 4, manometer 4 all connects through pressure gauge joint 41, and simultaneously, manometer 4, pressure sensor 12 and central control unit 5 all connect on the computer through the wire, through computer control real-time slip casting, apply processes such as the reciprocating motion of axisymmetric stress and concrete column 7.
The pressure sensor 12 can measure the jacking force in the test, the friction force between the concrete column 7 and the thixotropic slurry in the jacking process can be calculated, the pressure gauge 4 can measure the applied air pressure, and the axial symmetric stress of the pressure chamber 2 and the grouting pressure of the grouting channel 23 can be reasonably regulated and controlled by analyzing the measurement result.
When the invention is used specifically, the operation is as follows:
1) before the test, the grouting system and the data acquisition and control system are connected and connected with the pressure chamber 2, and the surrounding rock model preparation chamber 22 in the pressure chamber 2 needs to be filled with model soil bodies and compacted in layers according to requirements.
2) And (3) performing a pre-test, connecting a tensile joint 72 of the double-column tensile-compression testing machine 1 with a built-in bolt 71 at the upper part of the concrete column 7 under the condition that no axisymmetric stress is applied to the pressure chamber 2, and enabling the concrete column 7 to move up and down in the pressure chamber 2 by utilizing the up-and-down reciprocating motion of the cross beam 11.
3) When the test is started, firstly, thixotropic slurry is injected into the grouting channel 23 in the pressure chamber 2 through the grouting joint 66, the pneumatic booster 3 is opened after the grouting channel is full, air pressure is added into the pressure chamber 2 to simulate real formation surrounding rock pressure, the formed axisymmetric stress uniformly acts on the thixotropic slurry in the grouting channel 23 through the rubber film 28 on the surface of the surrounding rock model preparation chamber 22, the slurry can permeate into soil around a pipe to form a compact infiltration block under the action of the pressure, the pneumatic booster 3 is closed, and meanwhile, the pneumatic joint 65 is closed to prevent the leakage of the air pressure.
4) And (4) continuing grouting, and repeating the step 3) until the grouting channel 23 can be filled with the slurry under the applied axisymmetric stress condition.
5) Starting the double-column type tension and compression testing machine 1, pushing the concrete column 7 through the movement of the cross beam 11, simulating the jacking process of a pipeline, and when the second section of concrete column 7 enters the pressure chamber 2, supplementing slurry to the grouting channel 23 by using a grouting system until the last section of concrete column 7 is jacked in, thereby really achieving real-time slurry supplementing.
6) Through the five steps, a real and complete push pipe slurry sleeve can be formed, and the friction reducing and drag reducing mechanical properties of the slurry sleeve are measured under the coordination of a data acquisition and control system.
Although the embodiments of the present invention have been described with reference to the accompanying drawings, it is not intended to limit the scope of the present invention, and it should be understood by those skilled in the art that various modifications and variations can be made without inventive efforts by those skilled in the art based on the technical solution of the present invention.
Claims (10)
1. A pipe jacking slurry sleeve resistance reducing performance measuring device under an axial symmetric stress condition is characterized by comprising a double-column type tension and compression testing machine and a pressure chamber arranged in the double-column type tension and compression testing machine, wherein a cylindrical space for placing a concrete column is vertically arranged in the middle of the pressure chamber, a built-in bolt is arranged at the upper part of the concrete column and is connected with one end of a tension joint, the other end of the tension joint is connected with a cross beam of the double-column type tension and compression testing machine, the concrete column is pushed and pulled back and forth in the vertical direction by utilizing the reciprocating motion of the cross beam, a surrounding rock model preparation chamber and a grouting channel which are communicated are arranged in the pressure chamber at the periphery of the cylindrical space, the upper end of the pressure chamber is connected with an air pressure booster through an air pressure joint, the pressure in the pressure chamber is boosted through conveying air, the upper end of the grouting channel is connected with a grouting system through the grouting joint, the grouting system performs grouting to the grouting channel to realize the preparation of the surrounding rock model, and the subsequent jacking process can be used for supplementing slurry in real time, and the data acquisition and control system is used for collecting pressure data of the double-column type tension and compression testing machine, the grouting system and the air pressure booster and controlling the operation of the whole set of device.
2. The apparatus for testing the drag reduction performance of a pipe-jacking slurry sleeve under the condition of axisymmetric stress as claimed in claim 1, wherein the pressure chamber comprises a cylindrical shell, an upper plate, a base and a lower sealing plate, the upper end and the lower end of the cylindrical shell are respectively clamped in the annular grooves at the bottom of the upper plate and on the upper surface of the base, the lower sealing plate is fixedly connected to the center of the bottom of the base, the peripheries of the upper plate and the base are fixedly connected through a plurality of connecting pieces, a grouting plate is fixed on the upper plate, a grouting joint communicated with a grouting channel is arranged on the grouting plate, the centers of the grouting plate, the upper plate, the base and the lower sealing plate are provided with concentric cylindrical spaces, the grouting channel is tightly attached to the periphery of the cylindrical spaces, the periphery of the grouting channel is a surrounding rock model preparation chamber, and the upper plate is further provided with a pneumatic joint communicated with the surrounding rock model preparation chamber.
3. The device for measuring the drag reduction performance of the pipe-jacking slurry sleeve under the condition of axial symmetric stress as claimed in claim 2, wherein the diameter of the cylindrical space at the centers of the grouting disc, the upper disc and the base is equal to the diameter of the concrete column to be measured; and a lubricant is coated on the contact surface of the upper disc and the concrete column.
4. The apparatus for determining the drag reduction performance of a pipe-jacking mud sleeve under the condition of axisymmetric stress as claimed in claim 2, wherein the top and the bottom of the surrounding rock model preparation chamber are respectively provided with a sample cover and a sample base, the inner surface of the surrounding rock model preparation chamber is provided with a rubber membrane, the lower end of the rubber membrane is fixed by the sample base, and the upper end of the rubber membrane is inserted into the sample cover and the surrounding rock soil body.
5. The apparatus for determining the drag reduction performance of a pipe-jacking slurry sleeve under the condition of axial symmetric stress as claimed in claim 2, wherein O-shaped rings are arranged on the contact surfaces of the grouting disc and the concrete column and the contact surfaces of the base and the concrete column; rubber pads are arranged in the annular grooves at the contact positions of the upper disc, the base and the two ends of the cylindrical shell.
6. The apparatus for determining the drag reduction performance of a pipe-jacking slurry sleeve under the condition of axisymmetric stress as claimed in claim 2, wherein said lower sealing disc is a cylinder body with an I-shaped longitudinal section, the diameter of said cylindrical space at the center is larger than that of the concrete column, and the lower sealing disc is not in direct contact with the concrete column, leaving a certain gap.
7. The device for measuring the resistance reduction performance of the pipe-jacking slurry sleeve under the condition of the axisymmetric stress as claimed in claim 1, wherein the grouting system comprises an air pressure booster, a pressure gauge, a grouting tank and slurry stirring equipment, the size of the grouting tank is designed according to the concrete column in a ratio of 1:1, the top of the grouting tank is respectively connected with the pressure gauge through a pressure gauge joint, the air pressure booster is connected with the air pressure booster through an air pressure joint and is respectively used for detecting and controlling grouting pressure, and the bottom of the grouting tank is used for grouting a grouting channel through the grouting joint and performing real-time grouting in the subsequent jacking process; after being stirred by slurry stirring equipment, the thixotropic slurry is placed in a grouting tank, and screw caps are arranged on two sides of the upper part of the grouting tank, so that the thixotropic slurry is convenient to load and pour.
8. The apparatus according to claim 7, wherein the grouting tank comprises a cylindrical tank body and plugs at the upper and lower ends, the bottom of the cylindrical tank body is tightly connected with the lower end plug, the top plug is screwed on the upper end of the cylindrical tank body through a screw cap, and an O-shaped ring is arranged between the cylindrical tank body and the upper end plug.
9. The apparatus for testing the resistance-reducing performance of the pipe-jacking slurry sleeve under the condition of axisymmetric stress as claimed in claim 7, wherein the data acquisition and control system is composed of a pressure sensor, an air pressure booster, a pressure gauge and a central control unit, the pressure gauge is arranged between the air pressure booster and the pressure chamber and on the upper part of the grouting tank, the pressure sensor is arranged between the cross beam and the stretching joint, and the pressure gauge, the pressure sensor and the central control unit are all connected to the computer through data lines.
10. The method for measuring the resistance reduction performance of the pipe-jacking slurry sleeve under the condition of axisymmetric stress is characterized by comprising the following steps of:
1) before a test, connecting all parts of a grouting system and a data acquisition and control system, and connecting the grouting system and the data acquisition and control system with a pressure chamber, wherein a surrounding rock model preparation chamber in the pressure chamber needs to be filled with a model soil body and compacted in layers according to requirements;
2) performing a pre-test, connecting a tensile joint of the double-column type tension and compression testing machine with a built-in bolt at the upper part of the concrete column under the condition that no axisymmetric stress is applied to the pressure chamber, and enabling the concrete column to move up and down in the pressure chamber by utilizing the up-and-down reciprocating motion of a cross beam;
3) when a test is started, firstly, thixotropic slurry is injected into a grouting channel in a pressure chamber through a grouting joint, an air pressure booster is opened after the thixotropic slurry is filled, air pressure is added into the pressure chamber to simulate real formation surrounding rock pressure, the formed axisymmetric stress uniformly acts on the thixotropic slurry in the grouting channel through a rubber film on the surface of a surrounding rock model preparation chamber, the slurry can permeate into soil around a pipe under the action of the pressure to form a compact infiltration block, the air pressure booster is closed, and meanwhile, the air pressure joint is closed to prevent air pressure leakage;
4) continuing grouting, and repeating the step 3) until the grouting channel can be filled with the slurry under the applied axisymmetric stress condition;
5) starting a double-column type tension-compression testing machine, pushing a concrete column through the movement of a cross beam, simulating the jacking process of a pipeline, and when a second section of concrete column enters a pressure chamber, supplementing slurry to a grouting channel by using a grouting system until the last section of concrete column is jacked in, thereby really achieving real-time slurry supplement;
6) through the five steps, a real and complete push pipe slurry sleeve is formed, and the friction reducing and drag reducing mechanical property parameters of the slurry sleeve are measured under the coordination of a data acquisition and control system.
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