long anchor construction technology

combining with the engineering practice, considering the convenience of construction, low cost, etc., to ensure the quality of anchor construction, give full play to its role, and ensure the construction safety, three schemes of anchor construction are determined. The hole-forming of anchor holes in the three schemes is the same, and the hole-forming depth is 6m, and the position and direction are according to the design requirements. The difference between the three schemes lies in their rod body and anchoring technology.

I. end anchor grouting scheme

end anchor grouting is to anchor the anchor with chemical charge at the bottom end of the anchor after the anchor hole is formed, and then put it into grouting pipe and exhaust pipe to block the end of the anchor, and then carry out pressure grouting. It is characterized in that the chemical charge at the end contains two kinds of sealed chemical slurry. When the sealing layer is destroyed by external force during construction, the two kinds of slurry react reversely, and the anchor rod can be pre-anchored quickly, which can exert certain prestress on the anchor rod system. The schematic diagram of its anchor rod is as shown in the figure:

1. Construction method

A. Preparation: the drilling rig is in place and the power supply and water supply pipelines are connected.

B, measuring eye arrangement: mark the eye position with paint according to the designed anchor spacing and the actual situation of surrounding rock bedding and joint distribution. When laying holes, the bedding and joint development parts should be densely laid.

C, drilling: drilling with a two-arm hydraulic drilling trolley, when drilling, the drill pipe is perpendicular to the rock surface or bedding surface.

D, hole cleaning and inspection: use high-pressure wind to clean the stone chips and small stones in the hole, which is beneficial to the full contact between the slurry and the rock wall, and check the hole depth.

E, anchor rod processing: the anchor rod is made of grade Ⅱ φ 25 rebar, cut according to the design size, and tap the exposed end within 2cm, and the thread depth and the formed diameter match the anchor rod end pad.

F, putting in the chemical charge: send the chemical charge lightly into the bottom of the anchor hole with a PVC pipe slightly smaller than the hole diameter, send it in sections, and then pull out the PVC pipe. Then put the kraft paper ball as a pulp stopper.

G, anchor rod insertion: insert the anchor rod, tap it to the bottom of the hole with a hammer, and then rotate the rod body to destroy the spacer layer of two kinds of slurry in the chemical explosive bag, so that the chemical slurry can react quickly to anchor the end of the anchor rod. It takes about 3 minutes for the slurry to solidify, during which the anchor rod needs to be stabilized manually.

H, mounting the backing plate and nut: after the end anchor is completed, insert the φ6 exhaust pipe and φ1 grouting pipe, then seal the backing plate, anchor plate and M2 nut, and apply a small amount of pretension to tighten it, which is beneficial to the stability of the rock mass.

I. grouting: BW25 mortar pump is used for grouting, and the grouting pressure is .1 ~ .3 MPa. The slurry material is 1: 1.5 cement mortar, and the mortar is mixed by the on-site mortar mixer, and the mixing time is not less than 3 minutes. When grouting, it is injected at a uniform speed until the slurry from the exhaust pipe flows out evenly, and the grouting is full.

2. Precautions

A. Drilling, which should be perpendicular to the joint surface of rock, and the axis of anchor rod should intersect with the main structural surface or slip surface of rock mass at a large angle. Radial anchor rod shall not be used mechanically, and it shall be adjusted appropriately according to the site conditions.

B, when the chemical charge is put into the blockage, it is necessary to ensure that the blockage is tight, so as to avoid the chemical slurry overflowing the end anchor section and causing false anchoring.

C, during the anchoring time of the chemical charge, the anchor rod must be kept stable, and it is not allowed to shake or rotate, so as to ensure the anchoring quality.

D, on the plate, such as uneven orifice, mortar should be used to smooth processing.

E, before the anchor is not anchored, it is self-important, so the anchor should be prevented from slipping and hurting people.

3. process flow diagram

2. drug pack anchoring scheme

drug pack anchoring is to directly anchor the bolt hole with fully wetted anchoring drug pack instead of grouting. The anchoring charge is a mixture of dry powdery cement mortar and powdery accelerator wrapped in a strip with special permeable paper, which is soaked in water and fully wetted before being directly anchored. It is characterized by convenient use, simple process and fast construction speed, but it is difficult to apply certain prestress and ensure that the anchor rod is located in the center of the anchor hole.

1. construction method

a. preparation: the drilling rig is in place and the power supply and water supply pipelines are connected.

B, measuring eye arrangement: mark the eye position with paint according to the designed anchor spacing and the actual situation of surrounding rock bedding and joint distribution. When laying holes, the bedding and joint development parts should be densely laid.

C, drilling: drilling with a two-arm hydraulic drilling trolley, when drilling, the drill pipe is perpendicular to the rock surface or bedding surface.

D, hole cleaning and inspection: use φ18 elbow steel pipe to blow high-pressure wind to clean the stone chips and small stones in the hole, which is beneficial to the full contact between the slurry and the rock wall, and check the hole depth.

E, anchor rod processing: φ Φ25II grade rebar is adopted, and the material is cut according to the design size.

F, wetting of the medicine bag: soak the medicine bag in clean water for about 1-15 minutes (specific time is according to the instruction manual), so that the medicine bag is fully wet but cannot solidify, and its appearance is judged to be soft and uniform by gentle kneading with hands.

G, charge insertion: after the charge is pushed to the bottom with a PVC tube with a slightly larger aperture than the charge, the PVC tube is pulled out, and each charge is fed according to this method until the feed quantity meets the requirements. The quantity of charge to be loaded needs to be calculated and determined, because the anchor rod of this project is 6 meters long, and the sum of mortar volume and steel bar volume is the whole anchor hole volume.

H, anchor rod insertion: the anchor rod is forced into the anchor hole by hammering or pneumatic rock drill.

2. Process flow diagram (omitted)

3. Precautions

A. Drilling, which should be perpendicular to the joint plane of rock, and the axis of anchor rod should intersect with the main structural plane or slip plane of rock mass at a large angle. Radial anchor rod shall not be used mechanically, and it shall be adjusted appropriately according to the site conditions.

B, before using the anchoring charge, it is necessary to check whether the anchoring charge is hardened or not.

C, the soaking time of anchoring agent should be strictly controlled, and it is determined by experiments that the explosive bag can not be completely wetted, resulting in incomplete hydration of cement mortar, and the soaking time can not be too long, resulting in solidification of anchoring agent before bolt insertion.

D, in order to fix the anchor rod in the center of the anchor hole and make the anchoring agent evenly wrapped around the anchor rod, a stopper can be installed before the anchoring agent is put in.

E, before the anchor is not anchored, it is self-important, to prevent the anchor from slipping and hurting people.

F, it is forbidden to hang heavy objects before the mortar reaches the anchorage strength.

III. High-strength hollow grouting anchor scheme

XLM high-strength hollow grouting anchor is an anchor which integrates anchor and grouting pipe. It is implanted, and the anchor is reinforced quickly by grouting. The anchor is hollow and the external structure is threaded, which is convenient for the cement mortar and anchor to be fully wrapped after grouting and slurry solidification. Its characteristics are that the anchor rod can be quickly implanted into the anchor hole, the anchor head at the end can quickly act to fix the anchor rod in the center of the hole, and the threaded structure of the rod body can facilitate the installation and prestress of the grout stopper. Schematic diagram of its anchor rod (omitted)

1. Construction method

A. Preparation: the drilling rig is in place and the power supply and water supply pipelines are connected.

B, measuring eye arrangement: mark the eye position with paint according to the designed anchor spacing and the actual situation of surrounding rock bedding and joint distribution. When laying holes, the bedding and joint development parts should be densely laid.

C, drilling: drilling with a two-arm hydraulic drilling trolley, when drilling, the drill pipe is perpendicular to the rock surface or bedding surface.

D, hole cleaning and inspection: use φ18 elbow steel pipe to blow high-pressure wind to clean the stone chips and small stones in the hole, which is beneficial to the full contact between the slurry and the rock wall, and check the hole depth.

E, anchor insertion: insert the XLM high-strength hollow grouting anchor rod with the anchor head installed into the anchor hole, rotate the rod body to the left, and the anchor head will expand immediately until the anchor is anchored.

F, install the grout stopper, backing plate and nut: install the grout stopper, backing plate and nut at the tail of the anchor rod.

G, grouting: BW25 mortar pump is used for grouting, and the grouting pressure is .1 ~ .3 MPa. The slurry material is 1: 1.5 cement mortar, and the mortar is mixed by the on-site mortar mixer, and the mixing time is not less than 3 minutes. When grouting, inject at a uniform speed. If high-pressure grouting is needed, just wait until the pointer on the pressure gauge rises to the design pressure.

2. Precautions

A. Drilling, which should be perpendicular to the joint surface of rock, and the axis of anchor rod should intersect with the main structural surface or slip surface of rock mass at a large angle. Radial anchor rod shall not be used mechanically, and it shall be adjusted appropriately according to the site conditions.

B, when the anchor rod is inserted and expanded, make sure that the anchor head is fully expanded and the anchor rod is fastened to prevent the anchor rod from slipping and hurting people.

C, grouting should be injected slowly and uniformly, so as to reduce the generation of bubbles in the slurry and the phenomenon of punching.

3. process flow diagram (omitted)