Anchor rod capable of monitoring surrounding rock temperature field and applying pre-tightening force and surrounding rock temperature field monitoring method

Abstract

The invention discloses an anchor rod capable of monitoring a surrounding rock temperature field and applying pre-tightening force and a corresponding surrounding rock temperature field monitoring method. The anchor rod comprises a rod body structure and a temperature sensor monitoring structure, the rod body structure comprises a rod body (2), a tray (3), a fastening device (4) and an anchoring agent (6), and the temperature sensor monitoring structure comprises a temperature sensor (9) and a shell protection device (11). The rod body (2) is of a hollow structure, a clamping groove is formed in the rod body (2) and used for clamping the shell protection device (11), and the temperature sensor (9) is installed in a gap between the shell protection device (11) and the rod body (2). The influence on the rock mass stability structure can be reduced. In addition, through connection of the temperature sensor flexible connecting device, the problem of mutual coordination deformation of the anchor rod and the temperature sensor can be solved.

Description

Technical Field

[0001] The present invention belongs to the field of tunnel temperature field monitoring, and specifically relates to a hollow grouting anchor rod capable of monitoring the temperature field changes of surrounding rocks such as underground liquefied natural gas storage tanks and applying pre-tightening force, and a corresponding surrounding rock temperature field monitoring method. Background Art

[0002] During the construction and operation of underground liquefied natural gas storage, changes in the surrounding rock temperature field have a significant impact on the safety and stability of the storage. Temperature changes not only cause thermal expansion and contraction of the surrounding rock, which in turn causes changes in the stress distribution of the rock mass, but may also affect the stability of the anchored surrounding rock, thereby affecting the long-term operating life of the storage. Especially in extreme temperature environments, fluctuations in the temperature field may cause surrounding rock cracks, anchor failures, or lining structure deformations, thereby increasing the risk of storage leakage and other safety accidents. Therefore, real-time monitoring of temperature field changes is crucial to ensure the safety of underground liquefied natural gas storage.

[0003] At present, underground temperature field monitoring mainly adopts the following three methods: 1) directly attaching temperature sensors to the surrounding rock or lining surface, and indirectly inferring the distribution of underground temperature field through surface temperature changes; 2) drilling holes in the tunnel to lay temperature sensors to detect temperature changes at different depths, thereby monitoring temperature fields at different levels; 3) installing temperature sensors on anchor rods to monitor the temperature and strain changes of anchor rods, and then inferring the temperature field and stress state of the surrounding rock. Although these methods can provide certain temperature data, they still have certain limitations in data accuracy and real-time performance:

[0004] 1) The temperature sensor on the lining surface is easily affected by the external environment and it is difficult to accurately reflect the temperature changes of the deep surrounding rock; 2) Although the temperature sensor arranged in the borehole can obtain temperature data at different depths, its installation and maintenance are relatively complicated, and the instability of data transmission may lead to monitoring blind spots; 3) The temperature sensor installed on the anchor rod can provide more accurate local temperature change information, but the anchor rod will deform during the force process. If the sensor is directly attached to the surface of the anchor rod, there will be deformation inconsistency and even sensor cracking. The sensor on the surface of the anchor rod is limited by the friction between the anchor rod and the rock, and the accuracy and sensitivity of the sensor limit its application effect under complex working conditions.

[0005] Therefore, the existing monitoring methods urgently need to be improved to enhance monitoring accuracy and reliability, so as to better ensure the safe operation of underground liquefied natural gas storage facilities. Summary of the invention

[0006] 1. Technical issues to be resolved

[0007] On one hand, the present invention aims to solve the problem that the existing anchor rods cannot effectively protect the temperature sensor from the influence of the external rock structure.

[0008] On the other hand, the present invention aims to solve the problem that the existing anchor rods cannot quickly and accurately measure the temperature field within 3-5 times the diameter of the tunnel inside the rock mass.

[0009] (II) Technical solution

[0010] The first aspect of the present invention proposes an anchor rod capable of monitoring the temperature field of surrounding rocks and applying preload, the anchor rod comprising a rod body structure and a temperature sensor monitoring structure, the rod body structure comprising a rod body, a tray, a fastening device and an anchoring agent; the temperature sensor monitoring structure comprising a temperature sensor and an outer shell protection device; the rod body is a hollow structure with a card slot inside, the card slot is used to clamp the outer shell protection device; the temperature sensor is installed in the gap between the outer shell protection device and the rod body

[0011] According to a preferred embodiment of the present invention, the temperature sensor monitoring structure further includes a flexible connection device, and the temperature sensor is adhered to the inner surface of the rod body 2 through the flexible connection device.

[0012] According to a preferred embodiment of the present invention, the rod body structure further comprises a fastening device; the fastening device is installed in the circumference of one end of the rod body located outside the anchor borehole, and is used to adjust the preload force between the tray and the surrounding rock.

[0013] According to a preferred embodiment of the present invention, the fastening device comprises a butterfly nut and an external thread that cooperates with the butterfly nut and is formed on the circumference of the rod body; the external thread is located on the outer surface of the rod body, and the rod body is connected to the butterfly nut through the external thread.

[0014] According to a preferred embodiment of the present invention, the connecting wire of the temperature sensor can withstand low temperatures within -40°C. At the same time, a connecting wire larger than the elongation of the anchor rod is reserved in the hole to adapt to the elongation deformation of the anchor rod.

[0015] Another aspect of the present invention provides a method for monitoring the temperature field of surrounding rocks, using the anchor rod capable of monitoring the temperature field of surrounding rocks and applying pre-tightening force.

[0016] According to a preferred embodiment of the present invention, the following steps are included:

[0017] Step S1, installing a temperature sensor on the inner wall of the anchor rod by means of a flexible connection;

[0018] Step S2, installing the anchor rod in the anchor rod drill hole opened in the surrounding rock;

[0019] Step S3, applying a pre-tightening force to the anchor rod;

[0020] Step S4: Connect the temperature sensor to the data collection system to monitor the surrounding rock temperature field.

[0021] According to a preferred embodiment of the present invention, in step S1, flexible connecting double-sided tape is pasted on the inner surface of the anchor rod at equal intervals, one side of the double-sided tape is pasted on the inner wall of the anchor rod, and the other side is pasted on the temperature sensor, and waterproof glue is applied. The wire of the temperature sensor is fixed on one side of the double-sided tape on the inner wall of the anchor rod, and passes through the double-sided tape under each temperature sensor in turn until it is connected to the tunnel surface.

[0022] According to a preferred embodiment of the present invention, in step S2, the rod body is placed into the anchor borehole; the anchoring agent is injected into the anchor rod body until the gap between the anchor and the rock is filled; the rod body is fully rotated so that the anchoring agent is in full contact with the inner wall of the anchor borehole.

[0023] According to a preferred embodiment of the present invention, in step S3, the fastening device includes a butterfly nut and an elastic gasket. After the anchoring agent is completely solidified, the butterfly nut of the fastening device is rotated so that the elastic gasket is just in a stressed state to apply a pre-tightening force to the anchor rod.

[0024] (III) Beneficial effects

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The anchor rod of the present invention can be installed with a temperature sensor, which can avoid the problem of re-drilling and destroying the integrity and stability of the rock. The tunnel anchor rod can be used to drill holes directly, and the temperature strain sensor can be installed on the anchor rod body to reduce the impact on the stability structure of the rock mass.

[0027] 2. The temperature sensor in the present invention is on the inner surface of the anchor rod and is connected by a flexible connection device of the temperature sensor, which can solve the problem of coordinated deformation between the anchor rod and the temperature sensor. At the same time, it avoids the phenomenon that the anchor rod surface is attached to the sensor and the anchor rod surface holding force causes the sensor to be damaged.

[0028] 3. The temperature sensor data of the present invention can be directly transmitted to a computer to realize real-time temperature field monitoring output. At the same time, the temperature output system can be adjusted in real time according to the 0°C isotherm to realize macro-control of the cryosphere. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of anchoring surrounding rocks using an anchor rod capable of monitoring the temperature field of surrounding rocks and applying pre-tightening force according to an embodiment of the present invention.

[0030] Figure 2 It is a schematic diagram of the rod structure of an anchor rod capable of monitoring the temperature field of surrounding rocks and applying pre-tightening force in one embodiment of the present invention.

[0031] Figure 3It is a schematic structural diagram of an anchor rod body capable of monitoring the temperature field of surrounding rocks and applying pre-tightening force in one embodiment of the present invention.

[0032] Figure 4 It is a schematic structural diagram of a butterfly nut and a tray of an anchor rod capable of monitoring the temperature field of surrounding rocks and applying pre-tightening force in one embodiment of the present invention.

[0033] Figure 5 The figure is a schematic diagram of the layout of anchor temperature monitoring points according to an embodiment of the present invention.

[0034] Figure 6 It is a schematic diagram of the temperature field of anchor monitoring according to an embodiment of the present invention. DETAILED DESCRIPTION

[0035] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0036] In view of the deficiencies of the prior art, the present invention provides an anchor rod capable of monitoring the temperature field of surrounding rocks and applying a pre-tightening force.

[0037] Figure 1 It is a schematic diagram of anchoring surrounding rocks using an anchor rod capable of monitoring the temperature field of surrounding rocks and applying pre-tightening force according to an embodiment of the present invention. Figure 1 The tunnel surrounding rock 8 is shown in the figure, and an anchor rod drilling hole 1 is opened on the surface of the tunnel surrounding rock 8, one end of the anchor rod is located inside the anchor rod drilling hole 1, and the other end of the anchor rod is located outside the anchor rod drilling hole 1. The anchor rod of the present invention comprises a rod body structure and a temperature sensor monitoring structure, the rod body structure comprises a rod body 2, a tray 3, a fastening device 4, and an anchoring agent 6, and the temperature sensor monitoring structure comprises a temperature sensor 9, a flexible connecting device 10, and a shell protection device 11. The rod body 2 is a threaded steel tube.

[0038] Figure 2 Schematic diagram of the rod structure of the anchor rod capable of monitoring the surrounding rock temperature field and applying pre-tightening force in the above embodiment of the present invention. Figure 2 As shown, the rod body structure of the anchor rod includes a rod body 2, which is a hollow structure with threads. There is a slot inside the rod body 2 to clamp a shell protection device 11, and a temperature sensor 9 is installed in the gap between the shell protection device 11 and the rod body 2.

[0039] As a further optimization solution, a slot is provided inside the rod body 2, and the housing protection device 11 can be buckled on the slot to protect the temperature sensor 9 from being affected by the injection of the anchoring agent.

[0040] As a further optimization solution, the outer side of one end of the anchor rod body 2 located in the anchor rod borehole 1 is a threaded surface, and the high roughness of the rod body 2 can improve the bonding effect between the anchoring agent and the anchor rod body.

[0041] As a specific example, the thickness of the rod body can be 2.5mm, 3mm, 3.5mm, 4mm. Common grouting pipe diameters are 8mm, 10mm, 12mm, and the rod body diameters are 16mm, 18mm, 20mm.

[0042] Figure 3 Schematic diagram of the structure of the anchor rod body capable of monitoring the surrounding rock temperature field and applying preload in the above embodiment of the present invention. Figure 3 As shown, the temperature sensor 9 is adhered to the inner surface of the rod body 2 of the anchor rod through the flexible connection device 10, and the rod body 2 of the anchor rod can be filled with grouting at the same time.

[0043] Preferably, the temperature sensor 9 is attached to the flexible connection device 10 and coated with waterproof glue. The flexible connection device 10 is characterized in that it can flexibly connect the inner surface of the anchor rod and the temperature sensor 9. When the anchor rod is strained, the temperature sensor 9 will not fall off.

[0044] More preferably, there are multiple temperature sensors 9, which can be installed at equal intervals on the inner surface of the rod body 2 in the length direction of the anchor rod. The installation density of the temperature sensors 9 can be adjusted according to actual conditions.

[0045] The type of the temperature sensor 9 is preferably a patch-type temperature sensor, and the flexible connection device 10 is preferably a cold-resistant and waterproof double-sided adhesive sponge adhesive.

[0046] The connecting wire of the temperature sensor is preferably able to withstand low temperatures within -40°C, and a connecting wire larger than the elongation of the anchor rod is reserved in the hole to adapt to the elongation deformation of the anchor rod.

[0047] Figure 4 FIG. 1 is a schematic diagram of the structure of the butterfly nut and tray of the anchor rod capable of monitoring the temperature field of the surrounding rock and applying pre-tightening force in the above embodiment of the present invention. Figure 4 As shown, the rod body 2 is circumferentially slidably connected to a tray 3, the tray 3 is located outside the anchor borehole 1, and a fastening device 4 is circumferentially installed at one end of the rod body 2 located outside the anchor borehole 1, and the fastening device 4 is used to adjust the preload force between the tray 3 and the tunnel surrounding rock 8.

[0048] After the anchor rod is inserted into the anchor rod borehole 1, the present invention uses a grouting device to inject the anchoring agent 6 into the gap between the anchor rod and the anchor rod borehole 1, thereby increasing the stability between the anchor rod and the anchor rod borehole 1, and uses the fastening device 4 to adjust the preload force applied by the anchor rod to improve the support capacity of the anchor rod. The anchor rod can effectively monitor the temperature strain field of the rock around the tunnel, and can conveniently and accurately apply the anchoring agent 6 and the preload force.

[0049] As a further optimization scheme, during grouting, the grouting device is connected to the left side rod body 2 of the anchor rod, and the anchor material is injected into the gap between the anchor rod body 2 and the anchor rod borehole 1 through the hole in the left side rod body through the grouting pressure. When the anchor 6 fills the gap between the rod body and the borehole 1 and the anchor rod body 2, the grouting is completed.

[0050] As a further optimization scheme, the fastening device is composed of a butterfly nut, an external thread that cooperates with the butterfly nut and is formed on the circumference of the anchor rod body, the external thread is located on the outer surface of the anchor rod body, the anchor rod body 2 is connected to the butterfly nut through the external thread, an elastic gasket 12 is installed between the butterfly nut and the tray 3, the elastic gasket 12 is arranged on the circumference of the anchor rod body 2, and a gasket is arranged between the tray 3 and the rock mass 8 to prevent leakage of the anchoring agent 6. By rotating the butterfly nut and adjusting the elastic force of the elastic gasket 12, the preload force of the anchor rod can be changed.

[0051] The material of the rod body, tray and fastening device of the anchor rod of the present invention is preferably Q345. The material of the slot shell is preferably PVC pipe or TPU material. The anchor material is preferably pure cement slurry, and the water-cement ratio is preferably 0.4:0.5.

[0052] The following is a method for monitoring the surrounding rock temperature field using the anchor rod capable of monitoring the surrounding rock temperature field and applying preload force according to the present invention. The method of the present invention comprises the following steps:

[0053] Step S1: installing a temperature sensor on the inner wall of the anchor rod by means of a flexible connection.

[0054] For example, the flexible connection double-sided tape 10 is pasted at equal intervals on the inner surface of the anchor rod body 2, one side of the double-sided tape is pasted on the inner wall of the anchor rod, and the other side is pasted on the temperature sensor 9, and waterproof glue is applied. The line 5 of the temperature sensor is fixed on one side of the double-sided tape on the inner wall of the anchor rod, and passes through the double-sided tape under each temperature sensor in turn until it is connected to the tunnel surface. Then, the outer shell protection device 11 is installed, and PVC flexible material is used as the outer shell protection device to test whether the temperature sensor can be used normally;

[0055] Step S2: installing the anchor rod in the anchor rod drill hole opened in the surrounding rock.

[0056] This embodiment takes an underground liquefied natural gas storage project as an example. The on-site excavation is a horseshoe-shaped tunnel. After the tunnel is excavated and formed, a total of 11 anchor rods are designed for support.

[0057] In step S2, the anchor drilling device may be used to open an anchor borehole 1 on the tunnel surrounding rock 8. For example, the anchor borehole 1 has a diameter of 20 mm, the anchor rod body 2 has an outer diameter of 16 mm, an inner diameter of 12 mm, a rod body thickness of 4 mm, and a rod body thread pitch of 2.5 mm.

[0058] The rod body 2 of the anchor rod is placed in the anchor rod borehole 1, and the anchoring agent 6 is injected into the anchor rod body 2 by using a grouting device until the gap between the anchor rod and the rock is filled, and the rod body is fully rotated to make the anchoring agent 6 fully contact with the inner wall of the anchor rod borehole 1 to increase its bonding performance. The anchoring agent material is pure cement slurry, and the water-cement ratio is preferably 0.4:0.5.

[0059] Step S3: applying pre-tightening force to the anchor rod.

[0060] After the anchoring agent 6 is completely solidified, the butterfly nut of the fastening device 4 is rotated to put the elastic gasket 3 in a stressed state, thereby applying a pre-tightening force to the anchor rod.

[0061] As a further optimization scheme, before turning the butterfly nut, the distance that the elastic gasket 12 should be compressed is calculated according to the preload force, and the number of turns that the butterfly nut 4 needs to be turned is calculated according to the distance and the pitch of the butterfly nut, and the butterfly nut is tightened according to the number of turns. If the number of turns is less than an integer, it is rounded up. For example, if the preload force to be applied is F, the stiffness coefficient of the elastic gasket 12 is k, the compression length of the elastic gasket is dx=F / k, and the pitch of the external thread on the anchor rod body 2 is p, then the number of turns that the butterfly nut 4 needs to be tightened is m=dx / p.

[0062] As a specific example, the butterfly nut 4 has a thickness of 30 mm, a pitch of 5 mm, a stiffness coefficient of the gasket 12 of 210 GPa, and a preload force of 50% of the maximum bearing capacity of the anchor rod.

[0063] Step S4: Connect the temperature sensor to the data collection system to monitor the surrounding rock temperature field.

[0064] As an example, after the underground liquefied natural gas storage tank is built, connect the temperature sensor to the data collection system.

[0065] Figure 5 FIG. 1 is a schematic diagram of the arrangement of anchor temperature monitoring points according to an embodiment of the present invention. Figure 5 As shown, in this embodiment, the anchor rods are arranged around the tunnel according to the designed anchor rod spacing, with a total of 11 anchor rods, including a tray with one end installed on the inner surface of the tunnel and the other end installed inside the rock. A total of 8 temperature monitoring points are set along the length direction of the anchor rods, and a temperature sensor is installed at each monitoring point. The temperature sensor is connected to the data acquisition device and the data storage device through a connecting line. After the anchor rods are installed, the temperature monitoring system is turned on to monitor the temperature of the anchor rods along the length direction in real time, and then monitor the temperature around the tunnel in real time.

[0066] Figure 6 FIG. 1 is a schematic diagram of the temperature field of anchor monitoring according to an embodiment of the present invention. Figure 6As shown, in this embodiment, according to the temperature monitored by 8 temperature monitoring points along the length direction of the anchor rod and the spatial position of the corresponding temperature monitoring point, the temperature of each monitoring point is marked, and the specific position of 0°C in each anchor rod is calculated according to the temperature linear heat transfer. The specific position of 0°C in each anchor rod is connected to obtain the 0°C isotherm. Similarly, the temperature isotherms of -10°C and 10°C are obtained.

[0067] As can be seen from the above, the present invention proposes a new anchor rod, which has a hollow grouting rod body structure with a temperature sensor. This anchor rod can protect the temperature sensor from the influence of the external rock structure, and at the same time, the anchor rod has good deformation coordination when generating elongation strain. The present invention also provides a monitoring method for the rock temperature field around the tunnel based on the above anchor rod, which can more quickly and accurately measure the temperature field within 3-5 times the diameter of the tunnel inside the rock mass, and provide certain field data support for the temperature field control of the underground liquefied natural gas storage.

[0068] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An anchor rod capable of monitoring the temperature field of surrounding rocks and applying preload, characterized in that: The anchor rod comprises a rod body structure and a temperature sensor monitoring structure; The rod structure comprises a rod body (2), a tray (3), a fastening device (4) and an anchoring agent (6); The temperature sensor monitoring structure comprises a temperature sensor (9) and a housing protection device (11); The rod body (2) is a hollow structure with a slot inside, and the slot is used to clamp the outer shell protection device (11); The temperature sensor (9) is installed in the gap between the shell protection device (11) and the rod body (2).

2. The anchor rod capable of monitoring the surrounding rock temperature field and applying preload as claimed in claim 1, characterized in that: The temperature sensor monitoring structure further comprises a flexible connection device (10), and the temperature sensor (9) is adhered to the inner surface of the rod body 2 via the flexible connection device (10).

3. The anchor rod capable of monitoring the surrounding rock temperature field and applying preload as claimed in claim 1, characterized in that: The rod structure also includes a fastening device (4); The fastening device (4) is installed on the circumference of one end of the rod body (2) located outside the anchor borehole (1) and is used to adjust the pre-tightening force between the tray (3) and the surrounding rock (8).

4. The anchor rod capable of monitoring the surrounding rock temperature field and applying pre-tightening force as claimed in claim 3, characterized in that: The fastening device (4) comprises a butterfly nut and an external thread that cooperates with the butterfly nut and is formed in the circumferential direction of the rod body (2); The external thread is located on the outer surface of the rod body (2), and the rod body (2) is connected to the butterfly nut via the external thread.

5. The anchor rod capable of monitoring the surrounding rock temperature field and applying pre-tightening force according to claim 1, characterized in that: The connecting wire of the temperature sensor can withstand low temperatures within -40°C. At the same time, a connecting wire larger than the elongation of the anchor rod is reserved in the hole to adapt to the elongation deformation of the anchor rod.

6. A method for monitoring surrounding rock temperature field, characterized in that: An anchor rod capable of monitoring the temperature field of surrounding rock and applying pre-tightening force as described in any one of claims 1 to 5 is used.

7. The method for monitoring the surrounding rock temperature field according to claim 6, characterized in that: The steps include: Step S1, installing a temperature sensor on the inner wall of the anchor rod by means of a flexible connection; Step S2, installing the anchor rod in the anchor rod drill hole opened in the surrounding rock; Step S3, applying a pre-tightening force to the anchor rod; Step S4: Connect the temperature sensor to the data collection system to monitor the surrounding rock temperature field.

8. The method for monitoring the surrounding rock temperature field according to claim 7, characterized in that: In step S1, flexible connecting double-sided tape (10) is pasted on the inner surface of the rod body (2) of the anchor rod at equal intervals, one side of the double-sided tape is pasted on the inner wall of the anchor rod, and the other side is pasted on the temperature sensor (9), and waterproof glue is applied. The wire (5) of the temperature sensor is fixed on one side of the double-sided tape on the inner wall of the anchor rod, and passes through the double-sided tape under each temperature sensor in turn until it is connected to the tunnel surface.

9. The method for monitoring the surrounding rock temperature field according to claim 7, characterized in that: In step S2, the rod body (2) is placed into the anchor borehole (1); the anchoring agent (6) is injected into the anchor rod body (2) until the gap between the anchor rod and the rock is filled; and the rod body is fully rotated so that the anchoring agent (6) is in full contact with the inner wall of the anchor borehole (1).

10. The method for monitoring the surrounding rock temperature field according to claim 9, characterized in that: In step S3, The fastening device (4) comprises a butterfly nut and an elastic gasket (12). After the anchoring agent (6) is completely solidified, the butterfly nut of the fastening device (4) is rotated so that the elastic gasket (12) is just in a stressed state, thereby applying a pre-tightening force to the anchor rod.

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