Extensible reaming self-anchoring anchor rod and supporting method thereof

Patent metadata

Field	Value
Publication number	US-10767480-B2
Application number	US-201715751808-A
Country	US
Kind code	B2
Filing date	Jun 7, 2017
Priority date	Nov 25, 2016
Publication date	Sep 8, 2020
Grant date	Sep 8, 2020

Abstract

Provided is a mounting method for an extensible reaming self-anchoring anchor rod, which is especially applicable to roadway construction in coal mines. A big helical structure is arranged on two rod sections of a sectional type anchor rod, a simple drill bit drills and reams a bore and cuts the coal mass in one operation, the outer diameter of the simple drill bit is smaller than the outer diameter of the big helical rod body, and the big helical structure accomplishes secondary reaming, self-drilling and self-anchoring in the drilling process; the big helical structure inhibits propagation and development of sheet cracks of the coal wall in the radial direction, and is embedded in the coal mass through a self-stabilization process of the rock mass.

First claim

The invention claimed is:

1. A method for installing an extensible reaming self-anchoring anchor rod in a coal mass, wherein said extensible reaming self-anchoring anchor rod, comprises a simple drill bit, an anchor rod body, and a pre-tightening device;
wherein the anchor rod body comprises a plurality of hexagonal drilling rod sections, a plurality of connecting sleeves having hexagonal connecting sections, and an extension rod section;
wherein the plurality of hexagonal drilling rod sections are connected with each other via the plurality of hexagonal connecting sleeves, and are connected at their tail end with the extension rod section via a connecting sleeve;
wherein each of the drilling rod sections has a first outer diameter and an axial through-hole inside of the drilling rod section, a helical structure having a second outer diameter greater than the first outer diameter outside of the drilling rod section, top threads outside of the rod section head end, a hexagonal connecting portion at a tail end or the drilling rod section, and a plurality of grouting holes communicating with the interior through-holes in a side surface of the rod section;
wherein each of the connecting sleeves has a connecting sleeve through-hole inside of it, a hexahedral connecting portion matching the hexagonal connecting portion of the drilling rod section in the interior at one end, and a threaded connecting portion matching the top threads of the extension rod section in the interior at the other end; and
wherein the pre-tightening device comprises a stop-grouting plug, a tray, and a nut that are arranged sequentially on the anchoring threads of the extension rod section;
said method comprising the following steps:
a. assembling a drill bit on a first drilling rod section;
b. connecting the hexagonal connecting portion at the tail end of the first drilling rod section to the hexagonal connecting sleeve of an onboard or individual jumbolter;
c. starting the jumbolter and using the drill bit driven by the jumbolter to drill and ream a bore in a wall of the coal mass one operation, whereupon due to the outer diameter of the drill bit being smaller than the outer diameter of the helical rod body, the helical structure accomplishes secondary reaming and self-anchoring in the coal mass;
d. discontinuing drilling leaving a tail part of the first drilling rod section exposed outside of the coal wall, and, optionally detaching the jumbolter from the tail part of the first drilling rod section;
e. connecting a second extension drilling rod section to the first drilling read section via the top threads with the threaded connecting portion of the connecting sleeve, mounting the jumbolter on the tail part of the second drilling section, and using the jumbolter to drive the second drilling rod section into the wall of the coal mass;
f. repeating steps d. and e.;
g. mounting a pre-tightening device onto the anchoring threads of the extension rod section, connecting the hexahedral portion at the tail end of the extension rod section to the jumbolter,
h. starting the jumbolter and drilling, and discontinuing drilling and finishing mounting of the extension rod section when the tray contacts with the wall of the coal mass;
i. repeating steps d to h to achieve desired anchor depth;
j. removing the jumbolter and tightening a nut on the tail end of the anchor to squeeze together the coal wall and the rod body in the radial direction to inhibit crack propagation and development in the wall of the coal mass;
k. utilizing the through-hole and the grouting holes in the anchor rod body to inject grout behind the face of the wall of the coal mass; and
optionally injecting additional grout as necessary for reinforcement.

2. The method according to claim 1 , wherein, the drill bit is a disposable drill bit made of steel, the harness of the steel exceeds at least 1.2 times of the hardness of the drilled coal mass, and the outer diameter of the drill bit is smaller than the outer diameter of the helical rod body by 2 mm-10 mm.

3. The method according to claim 1 , wherein, the outer diameter of the connecting sleeve is smaller than the outer diameter of the helical structure, and the connecting sleeve comprises a hexahedral connecting portion, a connecting sleeve through-hole, and a threaded connecting portion.

4. The method according to claim 1 , wherein, the length of the plurality of drilling rod sections is 800 mm-1,500 mm, and the length of the extension rod sections is 600 mm-1,200 mm.

5. The method according to claim 1 , wherein the helical drilling rod has a right handed helical direction.

6. The method according to claim 1 , wherein the helical drilling rod has a helical angle of 10°-60°.

7. The method of claim 1 , wherein the helical drilling rod has a helical pitch of 20 mm 100 mm.

8. The method of claim 1 , wherein the helical drilling rod has a helical height of 10 mm-30 mm.

9. The method of claim 1 , wherein the helical drilling rod has a helical thickness of 2 mm 20 mm.

Assignees

• Univ China Mining

Inventors

• Zhang Nong
• Ma Peng
• Han Changliang
• Xie Zhengzheng

Classifications

• E21D21/0046 Primary

  formed by a plurality of elements arranged longitudinally · CPC title

• E21D20/021

  Grouting with inorganic components, e.g. cement · CPC title

• E21D20/02

  with provisions for grouting · CPC title

• E21D20/003

  Machines for drilling anchor holes and setting anchor bolts · CPC title

• E02D5/74

  Means for anchoring structural elements or bulkheads (anchoring piles E02D5/54 {; anchored foundations E02D27/50}) · CPC title