A rock mass hole internal measuring rod centering device and installation method

Abstract

The present invention provides a device for straightening an in-hole measuring rod in a rock mass and an installation method thereof. The in-hole measuring rod straightening device includes a measuring hole drilled in the rock mass, a measuring rod and a protective pipe placed in the measuring hole. An anchor head is installed at the bottom end of the measuring rod, and a floating column with a cavity filled with a lightweight foaming material or air is installed on the measuring rod. The measuring rod, the anchor head and the floating column are placed together in the protective pipe, and the anchor head extends out of the protective pipe. The connection section between the protective pipe and the anchor body is sealed, cement slurry is injected between the protective pipe and the measuring hole, and the protective pipe is filled with clear water. A measuring rod straightener is installed at the orifice of the measuring hole. The sum of the weights of the measuring rod and the floating column is equal to the buoyancy force generated by them, and the floating column suspends the measuring rod in the middle of the measuring hole. The present invention uses the buoyancy force generated by the floating column placed in the clear water in the protective pipe to lift the measuring rod, and the measuring rod is located in the middle of the measuring hole, so that the measuring rod does not contact the wall of the protective pipe, and the entire extended measuring rod forms a straight rod, solving the problem that the measured value of the deformation of the rock mass at the bottom of the measuring hole is inaccurate due to the bending of the long and slender measuring rod in the hole under the action of gravity and the friction resistance generated by contacting the hole wall.

Description

Technical Field

[0001] The invention belongs to the technical field of geotechnical engineering, and relates to the deformation monitoring of deep rock masses. Specifically, it is a device for straightening an in-hole measuring rod of a rock mass and an installation method thereof. Background Art

[0002] At present, for the deep deformation in a rock mass, usually a measuring rod is used to lead the measuring point to the surface orifice of the hole, and a displacement meter is installed for measurement, or a dial gauge, a micrometer or a displacement sensor installed on a reference beam is directly used for measurement. The in-hole measuring rod is formed by butt-connecting short measuring rods with nuts or screw threads outside the hole to form a lengthened measuring rod longer than the hole depth, and a lengthened protective tube with the same length as the measuring rod is formed by sleeving short protective tubes. The measuring rod passes through the protective tube, and an anchor head is connected to the bottom end of the measuring rod. Sealing and fixing are carried out between the measuring tube and the anchor head, and then the measuring tube and the measuring rod are sent into the bottom of the hole together. Cement slurry is poured between the protective tube and the hole wall for sealing, and a multi-point displacement meter is installed at the orifice of the hole, or a dial gauge, a micrometer or a displacement sensor is directly used to measure the deformation of the deep rock mass.

[0003] In this measuring rod installation method, under the action of gravity, the long and slender lengthened measuring rod in the hole sinks and bends and presses against the inner wall of the protective tube. Due to the influence of the frictional resistance between the measuring rod and the protective tube, the lengthened measuring rod is restricted by the inner wall of the protective tube and cannot move forward freely. Generally, there is no measured value under small deformations. Although the deformation can be measured under small deformations, it is inaccurate, and the regularity of the measured load-deformation curve is poor. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the invention provides a device for straightening an in-hole measuring rod of a rock mass and an installation method thereof. The method adds a floating column filled with a lightweight foaming agent or air, and uses the buoyancy of water to suspend the measuring rod in the hole, which can avoid the contact between the measuring rod and the hole wall, so that there is no frictional resistance on the measuring rod, and the accuracy of rock mass deformation measurement can be improved.

[0005] To achieve the above technical purpose, the invention provides a device for straightening an in-hole measuring rod of a rock mass, including a measuring hole drilled in a rock mass and a measuring rod installed in the measuring hole. The device is characterized in that: the straightening device further includes a floating column, a protective tube and a measuring rod straightener. An anchor head is provided at the end of the measuring rod placed in the measuring hole; the floating column is a double-layer circular ring-shaped hollow columnar structure, the measuring rod is inserted into the inner central hole of the floating column, and a lightweight foaming material or air is filled in the outer cavity of the floating column; the protective tube is sleeved outside the floating column, and a water injection cavity is provided between its inner wall and the outer wall of the floating column, and a grouting cavity is formed between its outer wall and the rock wall of the measuring hole; the anchor head of the measuring rod extends out of the floating column and the protective tube and is placed in the grouting cavity, and the extended part of the measuring rod is in a sealed state with both the floating column and the protective tube; the measuring rod straightener is a sealing cover provided with a perforation for the measuring rod. After filling the grouting cavity with neat cement slurry and filling the water injection cavity with clear water, the measuring rod straightener is installed at the orifice of the measuring hole, and the outer end of the measuring rod extends out from the perforation of the measuring rod.

[0006] Further technical solution of the present invention: The measuring hole is a measuring hole drilled obliquely downward or vertically downward from the rock mass surface. The outer diameter of the protection pipe is smaller than the diameter of the measuring hole, and the outer diameter of the floating support column is smaller than the inner diameter of the protection pipe.

[0007] Preferred technical solution of the present invention: Both the inner and outer column bodies of the floating support column are made of light and hard plastic; the buoyancy generated by the measuring rod and the floating support column in clear water is equal to the sum of the weights of the measuring rod and the floating support column.

[0008] Preferred technical solution of the present invention: A sealing centering ring is provided at the bottom end of the protection pipe. The anchor head passes through the sealing centering ring and is sealed with sealant. The anchor head is placed in the grouting cavity and anchored by solidified cement slurry.

[0009] Preferred technical solution of the present invention: The measuring rod passes through the hole and is placed at the central position of the measuring rod aligner, and its diameter is equal to or greater than the outer diameter of the measuring rod by 2-4 mm; the central axes of the measuring rod perforation and the inner central hole of the floating support column are on the same straight line.

[0010] In order to achieve the above technical objectives, the present invention also provides an installation method for the above-mentioned measuring rod aligner in the rock mass hole, which is characterized in that the specific steps are as follows:

[0011] (1) Measure and set out according to the construction drawings, and use a geological drill to drill vertical downward and obliquely downward measuring holes in the rock mass. The hole diameter and hole direction are accurate. After the hole is formed, clean the hole wall as required;

[0012] (2) Connect the inner threads of the measuring rods into an extended measuring rod longer than the depth of the measuring hole at the surface hole opening. The extended measuring rod passes through the central hole of the floating support column, and an anchor head is installed at the bottom of the measuring rod;

[0013] (3) Sheath the extended measuring rod and the floating support column with multiple protection pipes. The anchor head at the bottom of the extended measuring rod is exposed outside the extended protection pipe. The anchor head is installed on the sealing centering ring, and the sealing centering ring and the extended protection pipe are sealed with sealant or sealing tape; and the outer diameter of the protection pipe is smaller than the diameter of the measuring hole, and the outer diameter of the floating support column is smaller than the inner diameter of the protection pipe;

[0014] (4) Slowly place the integrally formed anchor head, sealing centering ring, protection pipe, measuring rod and floating support column together into the predetermined hole depth of the measuring hole, and pour neat cement slurry between the protection pipe and the hole wall of the measuring hole;

[0015] (5) When the neat cement slurry reaches the design strength, fill the protection pipe with clear water, install a measuring rod aligner at the hole opening of the measuring hole, and the top end of the measuring rod passes through the measuring rod perforation at the central position of the measuring rod aligner;

[0016] (6) Install a displacement meter at the hole opening, or install a dial indicator, a dial gauge or a displacement sensor on the reference beam. The bottom end of the gauge rod is placed on the top end of the measuring rod, and the deformation value of the measuring point is read manually or collected automatically.

[0017] Preferred technical solution of the present invention: In step (5), the aperture of the central hole of the rod aligner is matched with the diameter of the rod, and the rod passes through the central hole of the rod aligner without contacting the hole wall to generate friction.

[0018] Preferred technical solution of the present invention: In step (5), the rod aligner is fixed at the orifice of the measuring hole by the neat cement slurry passing through it.

[0019] In the present invention, a floating column filled with a light foaming agent or air is provided outside the rod. Clear water is poured into the protection tube. The buoyancy generated by the rod and the floating column in the clear water is equal to the sum of the weights of the rod and the floating column. The buoyancy suspends the rod in the hole. The rod does not contact the hole wall, and there is no frictional resistance on the rod, avoiding the adverse effect of the frictional resistance on the deformation value of the measuring point. Under the condition of the tiny deformation of the measuring point in the deep rock mass, the rod moves forward equally with the deformation of the rock mass, so that the deformation of the rock mass at the bottom of the hole can be accurately measured at the orifice. Description of the Drawings

[0020] Figure 1 is the vertical sectional view of the rod and the floating column in the present invention;

[0021] Figure 2 is Figure 1 the sectional view AA' in

[0022] Figure 3 is the cross-sectional view of the floating column in the present invention;

[0023] Figure 4 is Figure 3 the sectional view BB' in

[0024] Figure 5 is the vertical sectional view of the rod aligner in the present invention;

[0025] Figure 6 The front view of the rod aligner in the present invention.

[0026] In the figure: 1 - rock mass, 2 - measuring hole, 3 - protection tube, 4 - rod, 5 - floating column, 500 - inner central hole, 501 - outer cavity, 502 - light foaming material or air, 6 - anchor head, 7 - rod aligner, 700 - rod perforation, 8 - water injection cavity, 9 - grouting cavity, 10 - sealing and centering ring. Specific Embodiments

[0027] Hereinafter, the specific embodiments of the technical solutions in the present invention will be clearly and completely described in conjunction with the drawings in the present invention.

[0028] Figures 1 to 6The attached drawing of the rock mass borehole inner measuring rod centering device in the embodiment is drawn in a simplified manner, and is only used to clearly and concisely illustrate the purpose of the embodiment of the present invention. The following technical solutions shown in the attached drawing are the specific solutions of the embodiment of the present invention, and are not intended to limit the scope of the present invention claimed. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0029] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "left", "right", etc. is based on the orientation or positional relationship shown in the attached drawing, or the orientation or positional relationship in which the product of the invention is usually placed during use, or the orientation or positional relationship commonly understood by those skilled in the art. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0030] The embodiment provides a rock mass borehole inner measuring rod centering device, as Figure 1 and Figure 2 shown, including a measuring hole 2 drilled in the rock mass 1 and a measuring rod 4 installed in the measuring hole 2. The measuring hole 2 is a measuring hole drilled obliquely downward or vertically downward from the surface of the rock mass 1. The centering device further includes a floating column 5, a protection tube 3 and a measuring rod centering device 7. An anchor head 6 is provided at the end of the measuring rod 4 placed in the measuring hole 2. The outer diameter of the protection tube 3 is smaller than the diameter of the measuring hole 2, and the outer diameter of the floating column 5 is smaller than the inner diameter of the protection tube 3. As Figure 3 and Figure 4 shown, the floating column 5 has a double-layer circular ring-shaped hollow column structure. The inner and outer layer columns of the floating column 5 are both made of light and hard plastic. The measuring rod 4 is inserted into the inner central hole 500 of the floating column 5. The diameter of its inner central hole 400 is slightly larger than the outer diameter of the measuring rod 4. Lightweight foaming material 502 is filled in the outer cavity 501 of the floating column 5. After the measuring rod 4 is fixed, the outer wall of the floating column does not contact the inner wall of the protection tube under the buoyancy of water, avoiding the generation of frictional resistance. Figure 5 and Figure 6 shown, the measuring rod centering device 7 is a sealing cover provided with a measuring rod through hole 700. The measuring rod through hole 700 is located at the center of the measuring rod centering device 7 and its diameter is slightly larger than the outer diameter of the measuring rod 4, generally 2-4 mm larger. When the measuring rod 4 passes through the measuring rod through hole 700, it will not generate friction with the measuring rod centering device 7.

[0031] The rock mass borehole inner measuring rod centering device in the embodiment, as Figure 1 and Figure 2As shown in the figure, the protective pipe 3 is sleeved outside the floating support column 5. There is a water injection cavity 8 between its inner wall and the outer wall of the floating support column 5, and a grouting cavity 9 is formed between the outer wall and the measuring hole wall; the anchor head 6 of the measuring rod 4 extends out of the floating support column 5 and the protective pipe 3 and is placed in the grouting cavity 9. A sealing and centering ring 10 is provided at the bottom end of the protective pipe 3. The anchor head 6 passes through the sealing and centering ring 10 and is sealed with sealant to ensure that the part where the measuring rod 4 extends out is in a sealed state with the protective pipe 3. After injecting cement slurry, the anchor head 6 is anchored by the solidified cement slurry, so as to fix the end of the measuring rod 4 and make the measuring rod 4 placed on the central axis of the inner layer central hole 500 of the floating support column 5; after filling the grouting cavity 9 with neat cement slurry and filling the water injection cavity 8 with clear water, the measuring rod aligner 7 is installed at the orifice of the measuring hole 2, and the outer end of the measuring rod 4 extends out from the measuring rod perforation 700. The central axes of the measuring rod perforation 700 and the inner layer central hole 500 of the floating support column 5 are on the same straight line. The buoyancy generated by the measuring rod 4 and the floating support column 5 in clear water is equal to the sum of the weights of the measuring rod 4 and the floating support column 5. Under the action of buoyancy, the floating support column 5 equipped with the measuring rod 4 can be suspended in the protective pipe 3 without contacting the inner wall of the protective pipe 3. After the measuring rod 4 is fixed, it can be placed on the central axis of the measuring rod perforation 700 and the inner layer central hole 500 of the floating support column 5.

[0032] The following combines specific engineering examples to elaborate in detail on the installation method of the in-hole measuring rod aligning device in the present invention. The relevant parameters of this embodiment are as follows:

[0033] 1. Drilling: Straight hole in limestone, hole diameter Hole depth 60m, hole inclination ∠35°;

[0034] 2. Measuring rod: Stainless steel, diameter 0.4 kg / m, 2 m / root, the measuring rod is extended by internal threads for 60.2 m;

[0035] 3. Floating support column: The outer layer and the inner layer are made of rigid plastic, inner diameter Outer diameter 0.6 kg / m, the cavity is filled with lightweight foaming material, the buoyancy of the floating support column is 1.0 kg / m, it can withstand a pressure of 0.65 MPa, 2 m / root;

[0036] 4. Anchor head: Stainless steel, diameter 2 cm, length 20 cm;

[0037] 5. Protective pipe: Outer diameter Wall thickness 2 mm, 2 m / root, 30 roots, total length 60 m;

[0038] 6. Measuring rod aligner: Inner diameter of flange Outer diameter Height 3 cm, inner diameter of central hole Height 2 cm;

[0039] 7. Sealing and centering ring: Stainless steel, outer diameter The wall thickness is 5 mm, and the diameter of the middle hole

[0040] The specific installation method is as follows:

[0041] (1) Measure and set out according to the construction drawings. Use a geological drill to drill vertical or downward inclined measuring holes in the limestone rock mass. The hole diameter The hole depth is 60 m, the hole inclination is ∠35°, and the hole wall is cleaned;

[0042] (2) At the surface hole opening, thread-connect the measuring rod 4 with a length of 60.2 m. The floating support column 5 is sleeved on the measuring rod 4 through the central hole, and the anchor head 6 is installed at the bottom of the measuring rod 4;

[0043] (3) Pass multiple protective tubes through the measuring rod 4 and the floating support column 5. The anchor head 6 at the bottom of the measuring rod 4 is exposed outside the protective tube 3. The anchor head 6 is installed on the sealing and centering ring 10. The sealing and centering ring 10 and the protective tube 3 are sealed by winding multiple layers of sealing tape;

[0044] (4) As Figure 1 shown, slowly lower the integrally connected anchor head 6, sealing and centering ring 10, protective tube 3, measuring rod 4 in the protective tube, and floating support column 5 together to the predetermined hole depth of the measuring hole 2. Fill the protective tube 3 with clean water, and pour neat cement slurry into the gap between the protective tube 3 and the hole wall of the measuring hole 2;

[0045] (5) After the neat cement slurry reaches the design strength, install the measuring rod aligner 7 so that the inclination angle between the line connecting the deformation measuring point at the bottom of the measuring hole 2 and the center of the measuring rod aligner 7 is ∠35°. The measuring rod aligner 7 is directly placed at the measuring hole opening and fixed by the completely solidified neat cement slurry. The top end of the measuring rod 4 passes through the measuring rod perforation at the center of the measuring rod aligner 7, and the outer wall of the measuring rod 4 does not rub against the measuring rod perforation;

[0046] (6) Use a dial gauge or displacement sensor installed on the reference beam at the hole opening of the measuring hole 2. The bottom end of the gauge rod is in vertical contact with the top surface of the measuring rod 4, and the deformation value of the measuring point is read manually or collected automatically.

[0047] Since the measuring rod does not contact the hole wall and there is no frictional resistance on the measuring rod, the adverse effect of frictional resistance on the deformation value of the measuring point is avoided. Under the small deformation of the measuring point in the deep rock mass, the measuring rod moves forward equally with the deformation of the rock mass. Measure the displacement of the end part of the measuring rod at the hole opening, so that the deformation of the rock mass at the bottom of the hole can be accurately measured.

[0048] The above is only one embodiment of the present invention, and its description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims

1. A device for straightening an in-hole measuring rod in a rock mass, comprising a measuring hole (2) drilled in the rock mass (1) and a measuring rod (4) installed in the measuring hole (2). Characterized in that: The straightening device further comprises a floating support column (5), a protection pipe (3) and a measuring rod straightener (7). An anchor head (6) is provided at the end of the measuring rod (4) placed in the measuring hole (2). The floating support column (5) is a double-layer circular hollow columnar structure. The measuring rod (4) is inserted into the inner central hole (500) of the floating support column (5). A lightweight foaming material or air (502) is filled in the outer cavity (501) of the floating support column (5). The protection pipe (3) is sleeved outside the floating support column (5). An injection water cavity (8) is provided between the inner wall of the protection pipe (3) and the outer wall of the floating support column (5), and a grouting cavity (9) is formed between the outer wall of the protection pipe (3) and the rock wall of the measuring hole. The anchor head (6) of the measuring rod (4) extends out of the floating support column (5) and the protection pipe (3) and is placed in the grouting cavity (9). And the extending part of the measuring rod (4) is sealed and isolated from the protection pipe (3). A sealing and centering ring (10) is provided at the bottom end of the protection pipe (3). The measuring rod straightener (7) is a sealing cover provided with a measuring rod through hole (700). After filling the grouting cavity (9) with neat cement slurry and filling the injection water cavity (8) with clean water, the measuring rod straightener (7) is installed at the hole opening of the measuring hole (2), and the outer end of the measuring rod (4) extends out from the measuring rod through hole (700). The inner and outer column bodies of the floating support column (5) are both made of lightweight rigid plastic. The buoyancy generated by the measuring rod (4) and the floating support column (5) in clear water is equal to the sum of the weights of the measuring rod (4) and the floating support column (5).

2. A device for straightening an in-hole measuring rod in a rock mass according to claim 1, Characterized in that: The measuring hole (2) is a measuring hole drilled obliquely downward or vertically downward from the surface of the rock mass (1). The outer diameter of the protection pipe (3) is smaller than the diameter of the measuring hole (2), and the outer diameter of the floating support column (5) is smaller than the inner diameter of the protection pipe (3).

3. A device for straightening an in-hole measuring rod in a rock mass according to claim 1, Characterized in that: The anchor head (6) passes through the sealing and centering ring (10) and is sealed with sealant. The anchor head (6) placed in the grouting cavity (9) is anchored by the solidified neat cement slurry.

4. A device for straightening an in-hole measuring rod in a rock mass according to claim 1, Characterized in that: The measuring rod through hole (700) is placed at the central position of the measuring rod straightener (7), and its diameter is equal to or larger than the outer diameter of the measuring rod (4). The central axes of the measuring rod through hole (700) and the inner central hole (500) of the floating support column (5) are on the same straight line.

5. An installation method for the device for straightening an in-hole measuring rod in a rock mass according to any one of claims 1 to 4, Characterized in that The specific steps are as follows: (1) Measure and set out according to the construction drawings. Use a drill to drill a vertical or obliquely downward measuring hole in the rock mass. The hole diameter and hole direction are accurate. After the hole is formed, clean the hole wall as required. (2) Connect the internal threads of the measuring rods on the ground hole opening to form an extended measuring rod longer than the depth of the measuring hole. The extended measuring rod passes through the central hole of the floating support column. Install an anchor head at the bottom of the measuring rod. (3) Thread multiple protective tubes through the extended measuring rod and the floating support column. The bottom anchor head of the extended measuring rod protrudes from the extended protective tube. The anchor head is installed on the sealing centering ring, and the space between the sealing centering ring and the extended protective tube is sealed with sealant or sealing tape. Moreover, the outer diameter of the protective tube is smaller than the diameter of the measuring hole, and the outer diameter of the floating support column is smaller than the inner diameter of the protective tube. (4) Slowly lower the integrated anchor head, sealing centering ring, protective tube, measuring rod, and floating support column together to the predetermined hole depth in the measuring hole, and pour neat cement slurry between the protective tube and the measuring hole wall. (5) After the neat cement slurry reaches the designed strength, fill the protective tube with clear water. Install a measuring rod aligner at the orifice of the measuring hole, and the top of the measuring rod passes through the measuring rod perforation at the center of the measuring rod aligner. (6) Install a displacement meter at the orifice, or install a micrometer, dial indicator, or displacement sensor on the reference beam. The bottom end of the meter rod is placed on the top of the measuring rod, and the deformation value of the measuring point is read manually or collected automatically.

6. The installation method of a measuring rod aligning device for in-hole measurement in rock mass according to claim 5, characterized in that: In step (5), the diameter of the central hole of the measuring rod aligner matches the diameter of the measuring rod, and the measuring rod passes through the central hole of the measuring rod aligner without contacting the hole wall and generating friction.

7. The installation method of a measuring rod aligning device for in-hole measurement in rock mass according to claim 5, characterized in that: In step (5), the measuring rod aligner is fixed at the orifice of the measuring hole by the solidified neat cement slurry.

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