A device for testing the buoyancy of grout in post-wall grouting in shield construction

Abstract

The utility model discloses a kind of for wall grouting slurry liquid buoyancy testing device in shield construction, including lower container, lower container is equipped with a grouting mouth for slurry injection;Upper container, a glass rod for draining water is placed in upper container;And sliding support, sliding support is connected to lower container, the bottom of upper container vertically penetrates sliding support and extends to lower container inside.The utility model not only can make upper container guarantee settlement amount enough big, and not easy to sink to the bottom surface of lower container, the law that floating force changes with time is conveniently obtained, and with the aid of geometrical mechanics relation, the size of floating force is converted to obtain by reading the change of upper container scale, improve experimental efficiency.

Description

Technical Field

[0001] This utility model relates to a device for testing the buoyancy of grout injected behind the tunnel wall during shield tunneling. Background Technology

[0002] With the continuous development of urban rail transit, the demand for subway construction is increasing, and the shield tunneling method is a very common construction method in urban subway tunnel construction.

[0003] During shield tunneling, as the tunnel boring machine advances forward, the assembled segments detach from the shield tail. Grout needs to be injected into the gaps at the shield tail to compensate for ground losses and stabilize the segment structure.

[0004] The grout injected behind the tunnel wall is initially semi-liquid, inevitably providing a certain amount of buoyancy to the tunnel segment structure. This buoyancy is a significant cause of segment uplift, which reduces the effective assembly space for the segments, leading to problems such as segment overlap and contact with the shield tail, negatively impacting segment lifespan and seepage prevention performance. As the grout solidifies, the buoyancy it provides gradually dissipates. Current common calculation methods consider the initial buoyancy based on Archimedes' principle, neglecting the change of this buoyancy over time, i.e., F = ρgV. Utility Model Content

[0005] The purpose of this utility model is to provide a technical solution for testing the buoyancy of grout injected behind the tunnel wall during shield tunneling, which addresses the shortcomings of existing technologies. This solution not only ensures that the upper container has a sufficiently large settlement and is not prone to sinking to the bottom of the lower container, making it easy to obtain the law of buoyancy change over time, but also improves experimental efficiency by using geometric mechanical relationships to calculate the magnitude of buoyancy by reading the changes in the scale of the upper container.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A buoyancy testing device for grout injection behind the tunnel wall during shield tunneling is characterized by comprising a lower container, wherein the lower container is provided with a grout injection port for grout injection.

[0008] The upper container contains a glass rod for guiding the water flow.

[0009] And a sliding support, the sliding support is connected to the lower container, and the bottom of the upper container vertically passes through the sliding support and extends into the lower container.

[0010] The above structural design not only ensures that the upper container has a sufficiently large settling volume and is not prone to sinking to the bottom of the lower container, making it easy to determine the law of buoyancy change over time, but also allows for the calculation of buoyancy by reading the changes in the scale of the upper container using geometric mechanical relationships. This makes the operation flexible and convenient, improving experimental efficiency.

[0011] Furthermore, the sliding support is equipped with a limiting ring for horizontally constraining the upper container, which ensures that the upper container moves in the vertical direction and improves the accuracy of the slurry buoyancy test.

[0012] Furthermore, the thickness of the limiting ring is 1 to 1.5 cm, which helps to limit the upper container, ensure that the upper container moves in the vertical direction, and improve the test accuracy.

[0013] Furthermore, the sliding support is either fixedly connected to the top of the lower container or detachably connected to the top of the lower container.

[0014] Furthermore, both the outer surface of the upper container and the inner surface of the lower container are provided with protective films. These protective films can be disposable plastic protective films used for loading slurry.

[0015] Furthermore, the upper container is equipped with a scale for reading the amount of sedimentation of the upper container in the slurry.

[0016] Furthermore, both the lower and upper containers are cylindrical in shape, with openings at the top and closed bottoms.

[0017] Furthermore, the radius of the upper container is 3-5cm and the height is 15-20cm, while the radius of the lower container is 2-2.5 times that of the upper container and the height is 0.5 times that of the upper container.

[0018] Furthermore, both the lower and upper containers are made of plexiglass, with a wall thickness of 2–5 mm.

[0019] This utility model, by adopting the above-mentioned technical solution, has the following beneficial effects:

[0020] This invention not only ensures that the upper container has a sufficiently large settling volume and is not easily submerged to the bottom of the lower container, making it convenient to determine the law of buoyancy change over time, but also improves experimental efficiency by using geometric mechanical relationships to calculate the magnitude of buoyancy by reading the changes in the scale of the upper container. Attached image description:

[0021] The present invention will be further described below with reference to the accompanying drawings:

[0022] Figure 1 This is a schematic diagram of the structure of a buoyancy testing device for grouting fluid behind the tunnel wall during shield tunneling.

[0023] Wherein: 1-lower container; 2-upper container; 3-grouting port; 4-sliding support; 41-limiting ring; 5-glass rod; 6-protective film. Detailed Implementation

[0024] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0025] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0026] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0027] like Figure 1 As shown, this utility model discloses a buoyancy testing device for grouting fluid behind the tunnel wall during shield tunneling construction, comprising a lower container 1, an upper container 2, and a sliding support 4.

[0028] The lower container 1 is provided with a grouting port 3 for grout injection. The grouting port 3 is set at an upward angle to avoid grout leakage.

[0029] A glass rod 5 for guiding water flow is placed inside the upper container 2. The upper container 2 is equipped with a scale for reading the amount of sedimentation in the slurry.

[0030] Both the outer surface of the upper container 2 and the inner surface of the lower container 1 are provided with a protective film 6. The protective film 6 can be a disposable plastic protective film 6, used for loading slurry.

[0031] Both the lower container 1 and the upper container 2 are cylindrical in shape, and both the lower container 1 and the upper container 2 have an opening at the top and a closed structure at the bottom.

[0032] The upper container 2 has a radius of 3-5cm and a height of 15-20cm. The lower container 1 has a radius of 2-2.5 times that of the upper container 2 and a height of 0.5 times that of the upper container 2.

[0033] Both the lower container 1 and the upper container 2 are made of plexiglass, with a wall thickness of 2-5 mm.

[0034] The sliding support 4 is connected to the lower container 1, and the bottom of the upper container 2 extends vertically through the sliding support 4 and into the lower container 1.

[0035] The sliding support 4 is equipped with a limiting ring 41 for horizontally constraining the upper container 2, ensuring that the upper container 2 moves vertically and improving the accuracy of the slurry buoyancy test. The thickness of the limiting ring 41 is 1 to 1.5 cm, which is beneficial for limiting the upper container 2, ensuring that the upper container 2 moves vertically, and improving the test accuracy.

[0036] The sliding support 4 is either fixedly connected to the top of the lower container 1 or detachably connected to the top of the lower container 1. When a detachable connection is used, the sliding support 4 and the lower container 1 can be assembled via a threaded connection.

[0037] The above structural design not only ensures that the upper container 2 has a sufficiently large settling volume and is not prone to sinking to the bottom of the lower container 1, making it easy to obtain the law of buoyancy change over time, but also allows the magnitude of buoyancy to be calculated by reading the changes in the scale of the upper container 2 using geometric mechanical relationships. This makes the operation flexible and convenient, and improves experimental efficiency.

[0038] The principle of this invention is that as the solidification process progresses, the slurry transforms from a liquid to a solid. During this process, the buoyancy of the slurry gradually decreases over time. By placing a vertically movable upper container 2 in the slurry and measuring its settling at different times, the buoyancy force is calculated using Archimedes' principle F = ρgV. The ratio of the buoyancy force of the slurry at different times to the buoyancy force at the initial time is defined as k. f By plotting its change curve over time, the buoyancy change trend of this type of slurry can be reflected.

[0039] The slurry raw materials in this invention are prepared by weight percentage as follows: 15% to 20% fly ash, 3% to 6% cement, 6% to 10% bentonite, 50% to 54% medium sand, and the balance is water added to 100%.

[0040] The actual measurement should be performed according to the following steps:

[0041] The first step is to prepare the grout and, for example, inject it into the lower container 1 through the grouting port 3 after preparation.

[0042] The second step is to place the upper container 2 on the surface of the slurry, and then use the glass rod 5 to slowly pour water until the upper container 2 sinks to a distance of about 2cm from the bottom of the lower container 1. After the scale stabilizes, record the amount of water poured and the scale reading. Slowly remove the upper container 2 and pour out the water contained in it.

[0043] The third step is to place the upper container 2 on the surface of the slurry after 1 hour, and slowly inject the same amount of water as in the second step using a glass rod 5. After the scale stabilizes, record the scale reading at this time, and slowly remove the upper container 2 and pour out the water contained therein.

[0044] Repeat step three until the ruler reading shows no significant change.

[0045] After the experiment is completed, the solidified slurry should be removed from the testing device using the pre-set disposable plastic protective film 6.

[0046] Since all experimental data were obtained after the upper container 2 was in a static state, meaning the upper container 2 satisfies the static equilibrium equations, and since the sliding support 4 constrains the horizontal displacement and rotation of the upper container 2, only the forces in the vertical direction need to be considered:

[0047] G = mg = F s +F f

[0048] The upward force acting on the upper container 2 is the supporting force F provided by the solid phase. s The slurry buoyancy F provided by the liquid phase f The composition, where m includes the weight of the upper container 2 itself and the mass of the water it contains, can be measured separately and then superimposed. The volume of the upper container 2 immersed in the slurry can be calculated using the readings on a ruler, i.e., V = πR. 2 ·h, then substitute into the law of buoyancy to calculate the buoyancy of the slurry, that is:

[0049] F f =ρ 液 gπR 2 ·h

[0050] Where R is the outer diameter of the upper container 2, ρ 液 The density of the slurry in container 1 can be measured using a relative density meter.

[0051] Based on this, the buoyancy time-varying coefficient k can be defined. f , used to represent the proportional change of the total vertical force of the actual buoyancy station of the slurry, is calculated as: k f =F f / mg. Using data measured at different time periods, k can be plotted. f The -t curve is used to represent the change of buoyancy of the slurry over time.

[0052] The above are merely specific embodiments of this utility model, but the technical features of this utility model are not limited thereto. Any simple changes, equivalent substitutions, or modifications made based on this utility model to achieve essentially the same technical effect are all covered within the protection scope of this utility model.

Claims

1. A device for testing the buoyancy of grout injected behind the tunnel wall during shield tunneling, characterized in that: Includes a lower container, wherein the lower container is provided with a grout injection port for grout injection; An upper container, wherein a glass rod for guiding water is placed inside the upper container; The upper container has a sliding support connected to the lower container, and the bottom of the upper container extends vertically through the sliding support into the lower container.

2. The buoyancy testing device for grout behind the tunnel wall during shield tunneling construction according to claim 1, characterized in that: The sliding support is provided with a limiting ring for horizontally constraining the upper container.

3. The buoyancy testing device for grout behind the tunnel wall during shield tunneling construction according to claim 2, characterized in that: The thickness of the limiting ring is 1 to 1.5 cm.

4. The buoyancy testing device for grout behind the tunnel wall during shield tunneling construction according to claim 2, characterized in that: The sliding support is fixedly connected to the top of the lower container or detachably connected to the top of the lower container.

5. The buoyancy testing device for grout behind the tunnel wall during shield tunneling construction according to claim 1, characterized in that: Both the outer surface of the upper container and the inner surface of the lower container are provided with protective films.

6. The buoyancy testing device for grout behind the tunnel wall during shield tunneling construction according to claim 1, characterized in that: The upper container is equipped with a scale.

7. The buoyancy testing device for grout behind the tunnel wall during shield tunneling construction according to claim 1, characterized in that: Both the lower container and the upper container are cylindrical in shape, and both the lower container and the upper container have an opening at the top and a closed structure at the bottom.

8. The buoyancy testing device for grout behind the tunnel wall during shield tunneling construction according to claim 1, characterized in that: The upper container has a radius of 3-5 cm and a height of 15-20 cm. The lower container has a radius of 2-2.5 times that of the upper container and a height of 0.5 times that of the upper container.

9. A device for testing the buoyancy of grout injected behind the tunnel wall during shield tunneling, as described in claim 1, characterized in that: Both the lower and upper containers are made of plexiglass, with a wall thickness of 2-5 mm.

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