CN111122046A - Device and method for testing buoyancy on segment ring in consideration of shield tail wall post-grouting influence - Google Patents
Device and method for testing buoyancy on segment ring in consideration of shield tail wall post-grouting influence Download PDFInfo
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- CN111122046A CN111122046A CN202010015298.9A CN202010015298A CN111122046A CN 111122046 A CN111122046 A CN 111122046A CN 202010015298 A CN202010015298 A CN 202010015298A CN 111122046 A CN111122046 A CN 111122046A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L13/00—Devices or apparatus for measuring differences of two or more fluid pressure values
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Abstract
The invention relates to a device and a method for testing buoyancy on a segment ring in consideration of shield tail wall postgrouting influence. The testing method comprises the steps of testing the pore water pressure of the slurry at different height positions and obtaining the change rule of the buoyancy gravity of the slurry along with time according to the height difference between the pore water pressure and the pore water pressure. The device can consider the change process and change rule of the pore pressure and the buoyancy gravity of the grout along with the time under the action of different grouting liquid, different grouting pressures and different stratums. The device has simple instrument structure, convenient operation, easy mastering and simple and understandable test method, is convenient for a laboratory to carry out a large amount of mechanical test researches on floating and dislocation of the tube sheet ring by the slurry, and is also convenient for engineering application and popularization.
Description
Technical Field
The invention discloses a device and a method for testing buoyancy on a duct piece ring by considering shield tail wall post-grouting influence, and belongs to the technical field of underground engineering construction.
Background
With the rapid development of national economy and the rapid expansion of urban scale in China, urban traffic congestion has become a common problem in large cities. The adoption of large-flow subway transportation is an effective traffic organization form for the efficient operation of large cities, and the shield tunnel construction method becomes a mainstream method for urban subway construction due to the functions of small influence on urban traffic and safe, efficient and rapid tunneling.
The construction process of segment splicing at the tail part of the shield tunneling machine inevitably causes an annular gap, namely a shield tail gap, to exist between a spliced segment ring and a stratum. And the shield segment wall post-grouting is to actively control the stratum settlement and stabilize the segments by pumping slurry into the gaps in a shield tunnel construction method. The dual-liquid grouting method has the advantages that the dual-liquid grouting with the quick setting characteristic is adopted for synchronous grouting in foreign countries, the functional requirements of the grouting process after the wall are met, but the requirements on the quality of operating personnel are high, otherwise, frequent shutdown is easily caused to block the pipe, and the construction period is seriously influenced. Because of this, the grouting liquid after the shield tail wall in the domestic subway construction generally adopts single grout, and the initial setting time is too long, so that the segment ring which is just separated is in the wrapping of the liquid grout for a long time. Through preliminary calculation, the buoyancy of the slurry borne by the segment ring at the initial stage is nearly 4 times of the self weight of the segment ring, and the segment ring floating from the shield tail is inevitable. The on-site construction monitoring result of the existing subway shield tunnel shows that the upward floating amount of a segment ring just separated from the shield tail is several centimeters to ten and several centimeters, so that the segment assembling quality cannot meet the design requirement, and the phenomena of segment breakage, crack, slab staggering and leakage are comparable, thereby bringing huge challenges to future subway operation safety and tunnel maintenance.
The following two problems exist for solving the problem at present: 1) how the floating force of the slurry on the pipe sheet ring is determined and the change rule of the slurry on the pipe sheet ring along with time are not clear at present; 2) in order to reduce segment ring dislocation, various positioning bolts, positioning tenons and other various forms are developed on the side surface of the segment ring, and the contribution of the positioning bolts, the positioning tenons and the like to the shearing rigidity of joints between the segment rings is not clear at present. With the increasing importance of China on the subway construction quality, the solution of the problem is on schedule, which causes the high importance of China in the engineering and academic circles.
Disclosure of Invention
The invention provides a device and a method for testing buoyancy of a segment ring by considering the influence of shield tail wall post-grouting, aiming at solving the problems in the prior art and providing a novel device and a method for testing the buoyancy of slurry on the segment ring.
The technical solution of the invention is as follows: the device comprises a cylindrical organic glass long pipe, a pressurizing system, a pore pressure acquisition system and a drainage and water collection device, wherein the pressurizing system comprises an air compressor, a pressure regulating device, an air inlet valve and a connecting pipeline; the pore pressure acquisition system comprises two pore pressure sensors, a collector and a computer, wherein the two pore pressure sensors are arranged on the side wall of the cylindrical organic glass long pipe, the pore pressure sensors are connected with the collector, and the signal output end of the collector is connected with the computer; the drainage and water collection device comprises a drainage valve, a water collector, an electronic balance and a computer, wherein the drainage valve is arranged on the lower portion of the side wall of the cylindrical organic glass long tube and is connected with the water collector through a pipeline, the water collector is arranged on the electronic balance, and the signal output end of the electronic balance is connected with the computer.
The length of the organic glass cylindrical tube is 70cm, 2 round holes with the diameter of 1cm are laterally formed at positions 28cm and 27cm away from the bottom in the vertical direction, the inner side of the glass cylindrical tube is smooth, and the diameter of the tube is 8 cm.
And the computer is provided with pore pressure data acquisition software and drainage water collection acquisition software.
The testing method comprises the steps of testing the pore water pressure of the slurry at different height positions, obtaining the change rule of the buoyancy gravity of the slurry along with time according to the height difference between the pore water pressure and the slurry, specifically calculating the buoyancy gravity of the slurry by testing the pore water pressure in the slurry consolidation process based on the nature of the buoyancy as the comprehensive effect of the normal pressure of the slurry acting on the periphery of a pipe sheet ring, namely a calculation formula of the buoyancy gravity:
and then obtaining a buoyancy calculation formula of the slurry to the pipe sheet ring through the Archimedes law:
。
the invention has the beneficial effects that:
the invention can test the regular images of different slurries under different stratum conditions along with the change of time under different pressure conditions by designing a simple and convenient experimental device, accords with the actual conditions of an engineering field, can control the change of different slurries, stratums and overlying pressure by independent variables, obtains the change of the upper buoyancy of the slurries with different densities, specific gravities and fluidity under certain stratum and pressure conditions, influences of the stratum conditions with different permeability coefficients on the buoyancy gravity, simulates the influence of different grouting pressure differences on the buoyancy gravity, and reflects the change of the buoyancy of the pipe sheet under the engineering conditions along with the time through the buoyancy gravity.
Drawings
FIG. 1 is a schematic diagram of an upper buoyancy device.
Figure 2 is a schematic diagram of the upper buoyancy device.
FIG. 3 is a graph showing the variation of the floating force of slurry No. 1 under different pressures.
FIG. 4 is a graph showing the variation of the floating force of slurry No. 2 under different pressures.
Detailed Description
The technical scheme of the invention is further explained by combining the attached drawings
As shown in attached figures 1 and 2, the test device and the test method for the buoyancy on the segment ring considering the influence of shield tail wall post-grouting comprise a cylindrical organic glass long tube, a pressurizing system, a pore pressure acquisition system and a water drainage and collection device, and the test method comprises the steps of testing the pore water pressure of slurry at different height positions and obtaining the change rule of the buoyancy gravity of the slurry along with time according to the height difference between the pore water pressure and the pore water pressure.
The model is a cylindrical organic glass long pipe, a water outlet is formed in the bottom of the circular pipe, a stratum soil sample is laid on the circular pipe, then grouting liquid is poured into the circular pipe, a sealing cover is covered on the top of the organic glass long pipe, and the circular pipe is connected with an air compressor and set for given slurry consolidation pressure.
The pressurization system comprises an air compressor, a pressure regulating device, an air inlet valve and a connecting pipeline.
The pore pressure acquisition system comprises 2 pore pressure sensors, an acquisition device and computer pore pressure data automatic acquisition software.
The water draining and collecting system comprises a water draining device, a water collector and an electronic balance for collecting data in real time, and is connected to automatic collecting software of a computer.
The length of the organic glass cylindrical tube is 70cm, 2 round holes with the diameter of 1cm are laterally formed at positions 28cm and 27cm away from the bottom in the vertical direction, the inner side of the glass cylindrical tube is smooth, and the diameter of the tube is 8 cm.
The high-precision pore pressure meter is connected to the lateral hole opening position of the organic glass cylindrical tube, the pore pressure meter is connected with the data acquisition card, the data acquisition card is connected with the computer, and pore pressure numerical values of the 2 sensors are automatically acquired through data acquisition software.
Based on the nature of the comprehensive effect of normal pressure acting on the periphery of the pipe sheet ring by the slurry on buoyancy, the buoyancy gravity of the slurry can be calculated by testing the pore water pressure in the slurry consolidation process, namely a calculation formula of the buoyancy gravity:
and then obtaining a buoyancy calculation formula of the slurry to the pipe sheet ring through the Archimedes law:
。
example 1
A certain mortar proportion is selected, bentonite dry soil (calcium base), cement, fly ash, sand and water materials are prepared according to a certain proportion, the water-cement ratio of cement slurry is 0.429, and the specific component contents are shown in the following table 1.
TABLE 1 Per m3Content of each component of shield tail wall post-grouting liquid
| Slurry numbering | Cement/kg | Fly ash/kg | Bentonite/kg | Sand/kg | Water/kg | Lime |
| 1 | 158 | 368 | 105 | 842 | 523 | - |
| 2 | - | 390 | 120 | 950 | 523 | 60 |
Selecting a certain stratum material consisting of silt with the permeability coefficient of 3.0x10-5cm/s, the specific experimental steps are as follows:
1. the silt soil sample is selected as a stratum, the thickness of the stratum is about 15cm, and the permeability coefficient of the stratum is measured and recorded by a normal water head method.
2. Selecting No. 1 slurry for preparation, adding water after the powdery material is uniformly stirred, and uniformly stirring by using a stirring rod.
3. And (3) sticking filter paper to the inner punching position of the punching hole of the instrument, confirming that the filter paper completely covers the punching hole position, pouring slurry, connecting a hole pressure meter, turning on a power supply of the instrument to adjust the voltage to 24V, and reading the hole pressure reading by a USB (universal serial bus) connected computer.
And 4. covering a rubber mold on the upper part of the slurry, sealing the instrument, adjusting a voltage stabilizer to pressurize the instrument, opening a drainage valve and a pore pressure switch valve on the lower part of the instrument, and observing pore pressure readings.
5. When the pore pressure meter reading changes little, the pressure is relieved and the reading is stopped.
6. Repeating the above operations, replacing slurry or stratum or pressure, and calculating the buoyancy gravity changing along with time according to the obtained pore pressure reading.
As shown in fig. 3 and 4, according to the steps, the change of the buoyancy gravities of the two slurries with different pressures under the condition of the silt formation along with the time can be obtained.
From the above images, it can be seen that the buoyancy weight of slurry No. 2 initially appears larger in the same formation, and as the overburden force increases, its initial buoyancy weight may even approach 2 times its own specific gravity. In the slurry No. 2, the buoyancy gravity of the slurry No. 2 is obviously faster than that of the slurry No. 1 in the large pressure change rate after 40min, and the buoyancy gravity of the slurry No. 2 is at a lower value under the large pressure condition after 80min, so that the upper graph can reflect the change rule of the buoyancy of different slurries in the silt stratum under different pressures along with time. Under more working conditions, the influence change of the consistency and the density of the slurry on the buoyancy of the tube sheets can be reflected.
Claims (4)
1. The device is characterized by comprising a cylindrical organic glass long pipe, a pressurizing system, a pore pressure acquisition system and a drainage and water collection device, wherein the pressurizing system comprises an air compressor, a pressure regulating device, an air inlet valve and a connecting pipeline; the pore pressure acquisition system comprises two pore pressure sensors, a collector and a computer, wherein the two pore pressure sensors are arranged on the side wall of the cylindrical organic glass long pipe, the pore pressure sensors are connected with the collector, and the signal output end of the collector is connected with the computer; the drainage and water collection device comprises a drainage valve, a water collector, an electronic balance and a computer, wherein the drainage valve is arranged on the lower portion of the side wall of the cylindrical organic glass long tube and is connected with the water collector through a pipeline, the water collector is arranged on the electronic balance, and the signal output end of the electronic balance is connected with the computer.
2. The test device for the buoyancy of the segment ring considering the influence of the postgrouting of the shield tail wall, according to claim 1, is characterized in that the length of the organic glass cylindrical tube is 70cm, 2 circular holes with the diameter of 1cm are laterally arranged at positions which are 28cm and 27cm away from the bottom in the vertical direction, the inner side of the glass cylindrical tube is smooth, and the diameter of the tube is 8 cm.
3. The device for testing the buoyancy of the segment ring under the consideration of the shield tail wall post-grouting influence according to claim 1, wherein the computer is provided with pore pressure data acquisition software and drainage water collection acquisition software.
4. The test method of the test device for the buoyancy on the segment ring considering the shield tail wall post-grouting influence is characterized in that the test method obtains the change rule of the buoyancy gravity of the slurry along with the time by testing the pore water pressure of the slurry at different height positions and according to the height difference between the pore water pressure and the slurry, and specifically, the buoyancy gravity of the slurry is calculated by testing the pore water pressure in the slurry consolidation process based on the essence of the normal pressure comprehensive effect of the buoyancy acting on the periphery of the segment ring, namely the calculation formula of the buoyancy gravity:
and then obtaining a buoyancy calculation formula of the slurry to the pipe sheet ring through the Archimedes law:
。
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010015298.9A CN111122046A (en) | 2020-01-07 | 2020-01-07 | Device and method for testing buoyancy on segment ring in consideration of shield tail wall post-grouting influence |
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| CN202010015298.9A CN111122046A (en) | 2020-01-07 | 2020-01-07 | Device and method for testing buoyancy on segment ring in consideration of shield tail wall post-grouting influence |
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Citations (7)
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|---|---|---|---|---|
| US3795140A (en) * | 1971-12-29 | 1974-03-05 | Yokogawa Electric Works Ltd | Force responsive device |
| CN104655803A (en) * | 2015-01-30 | 2015-05-27 | 北京交通大学 | Tunnel grouting model testing device |
| CN108169459A (en) * | 2018-01-11 | 2018-06-15 | 河海大学 | EPB shield tunneling pressure chamber-spiral dumper is gushed laboratory apparatus and its experimental method |
| CN109974924A (en) * | 2019-03-15 | 2019-07-05 | 上海隧道工程有限公司 | Shield shield tail simultaneous grouting slurry buoyancy measuring device and its measurement method |
| CN110321623A (en) * | 2019-06-27 | 2019-10-11 | 中交一公局第三工程有限公司 | A kind of duct pieces of shield tunnel faulting of slab ends deformation acquisition methods |
| CN110346075A (en) * | 2019-06-27 | 2019-10-18 | 中交一公局第三工程有限公司 | A kind of duct pieces of shield tunnel slurries buoyancy experimental rig and test method |
| CN110456027A (en) * | 2019-08-22 | 2019-11-15 | 江苏建筑职业技术学院 | A kind of slurry shield knife cutting soil body generation mud membrane pilot unit contained |
-
2020
- 2020-01-07 CN CN202010015298.9A patent/CN111122046A/en active Pending
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3795140A (en) * | 1971-12-29 | 1974-03-05 | Yokogawa Electric Works Ltd | Force responsive device |
| CN104655803A (en) * | 2015-01-30 | 2015-05-27 | 北京交通大学 | Tunnel grouting model testing device |
| CN108169459A (en) * | 2018-01-11 | 2018-06-15 | 河海大学 | EPB shield tunneling pressure chamber-spiral dumper is gushed laboratory apparatus and its experimental method |
| CN109974924A (en) * | 2019-03-15 | 2019-07-05 | 上海隧道工程有限公司 | Shield shield tail simultaneous grouting slurry buoyancy measuring device and its measurement method |
| CN110321623A (en) * | 2019-06-27 | 2019-10-11 | 中交一公局第三工程有限公司 | A kind of duct pieces of shield tunnel faulting of slab ends deformation acquisition methods |
| CN110346075A (en) * | 2019-06-27 | 2019-10-18 | 中交一公局第三工程有限公司 | A kind of duct pieces of shield tunnel slurries buoyancy experimental rig and test method |
| CN110456027A (en) * | 2019-08-22 | 2019-11-15 | 江苏建筑职业技术学院 | A kind of slurry shield knife cutting soil body generation mud membrane pilot unit contained |
Non-Patent Citations (1)
| Title |
|---|
| 闵凡路 等: "泥浆在地层中的渗透特性试验研究", 《岩土力学》 * |
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Application publication date: 20200508 |