阅读说明：本技术 一种两步骤充填法支护方法 (Two-step filling method for supporting ) 是由 张君鹏 杨宁 孙胜 王怀勇 陆宇超 詹进 于涛 姜国坤 谭伟 董国强 于 2021-08-06 设计创作，主要内容包括：本发明公开了一种两步骤充填法支护方法,本方法在一步骤采场回采时,在采场内向两侧的矿体中施工安装锚索,提前支护二步骤采场顶板。二步骤矿体锚索施工分别从相邻的一步骤采场内进行凿岩,两边交错布置锚索孔,形成交叉网状锚固。通过锚索的悬吊作用、组合梁作用和挤压加固作用,使破碎不稳固岩层之间摩擦阻力和抗弯曲强度增大,增加了其稳定性,同时每根锚索周围破碎带岩块相互挤压,形成具有一定厚度的连续均匀压缩带,不仅能维持自身稳定,而且具有承载能力。同时浆液充入顶板岩层的节理、裂隙中,从而改善结构面的力学性质,提高破碎岩体的自承载能力,适时地控制岩体的进一步变形,防止岩块滑移、冒落失稳,维护顶板的稳定。(The invention discloses a two-step filling method for supporting, which is characterized in that when a stope is mined in a one-step stope, anchor cables are constructed and installed in ore bodies on two sides in the stope, and a stope top plate in the two steps is supported in advance. And in the second step, rock drilling is respectively carried out on the ore body anchor cable construction from the mining fields in the adjacent steps, and anchor cable holes are arranged on two sides in a staggered mode to form crossed net-shaped anchoring. Through the suspension effect, the combination beam effect and the extrusion reinforcement effect of anchor rope, make frictional resistance and bending strength increase between the broken unstable rock stratum, increased its stability, broken area rock mass extrudees each other around every anchor rope simultaneously, forms the continuous even compression area that has certain thickness, can not only maintain self-stability, has bearing capacity moreover. And meanwhile, the slurry is filled into joints and cracks of the top plate rock stratum, so that the mechanical property of a structural surface is improved, the self-bearing capacity of a broken rock body is improved, the further deformation of the rock body is timely controlled, the sliding, the caving and the instability of rock blocks are prevented, and the stability of the top plate is maintained.)

1. A two-step filling method for supporting is characterized in that: when the stope is stoped in the one-step stope, anchor cables are constructed and installed in the ore bodies of the two-step stope from the inner side of the stope to the two sides, and the top plate of the two-step stope is supported in advance.

2. The method of claim 1, wherein: the construction and installation of the anchor cable comprises the following steps:

(1) selection of anchor cable species

Selecting a non-prestressed anchor cable;

(2) anchor cable support parameter determination

The method comprises the steps of determining the diameter of an anchor cable, breaking force, the mesh degree of the anchor cable, the length of the anchor cable, the diameter of a drilled hole, the proportion of grouting materials and the direction of the drilled hole;

(3) drilling construction;

(4) installing an anchor cable;

(5) and (6) grouting.

3. The method of claim 2, wherein: in the step (2), the breaking force of the steel wire rope or the steel strand with the anchor cable diameter of 15-30 mm is 120-450 kN, and the length is 5000-50000 mm.

4. The method of claim 3, wherein: in the step (2),

net length of anchor cable D²Is calculated according to the following formulaCalculating:

s represents the area of the construction anchor cable, and n represents the number of the anchor cables arranged in a unit area;

the arrangement number n of the anchor cables in a unit area is determined by the following formula:

m represents a safety factor; r-breaking tension of the steel wire rope.

5. The method of claim 2, wherein: in the step (2), rock drilling is respectively carried out on anchor cable holes from the mining fields in the adjacent steps in the construction process, the anchor cable holes are arranged on two sides in a staggered mode to form crossed net-shaped anchoring, and the diameter of each drilled hole is 50-90 mm.

6. The method of claim 2, wherein: in the step (2), the horizontal distance multiplied by the vertical distance of the net width of the single-side anchor cable is correspondingly calculated according to the actual situation of the stability of the ore rock on the using site.

7. The method of claim 21, wherein: in the step (2), pure cement slurry is adopted for grouting, and the water-cement ratio is 0.65-0.80.

8. The method of claim 2, wherein: in the step (2), upward inclined drilling is adopted, and the inclination angle of the drilling hole is 40-60 degrees.

9. The method of claim 2, wherein: and (3) in the step (3), the drilling equipment is an anchor cable trolley or a medium-length hole/deep hole rock drill.

10. The method of claim 2, wherein: the step (4) comprises the following steps:

(1) preliminary preparation work

Performing oil stain treatment on the surface of the anchor cable and straightness treatment on the anchor cable, and manufacturing a barb at the head of the anchor cable for fixing a grouting pipe; cutting and binding the length of the anchor cable, wherein the length of the anchor cable is larger than the length of the anchor cable hole by 300-400mm, and conveying the anchor cable to a construction site after sleeving a protective sleeve on the anchoring section;

(2) on-site construction

Binding equal-length exhaust pipes on one side of the anchor cable, blowing the anchor cable hole clean, and sending the anchoring end of the anchor cable to the bottom of the anchor cable hole by using an anchor cable machine;

placing a pressure-resistant steel pipe on one side of the anchor cable body at the orifice as a grouting pipe, sending the grouting pipe into the hole for 300-300 mm, sealing the exhaust pipe by using a wood plug after the exhaust pipe is led out from the orifice, wherein the length of the seal is 250-300 mm, the anchor cable and the grouting pipe are exposed for 200-300mm, and fixing the anchor cable at the orifice;

then, injecting mortar in an outward-inward advancing mode, and installing a base plate and an anchorage device to stretch the anchor cable at the exposed end of the anchor cable after the cement mortar is solidified for 48 hours;

and after grouting of all the anchor cable holes is completed and the grouting is fully performed with the concrete, tensioning and locking each anchor cable by using the cable clamp to form the anchor cable anchoring net.

Technical Field

The invention belongs to the field of mining, and particularly relates to a two-step filling method supporting method.

Background

When stoping is carried out on the stope in the first step, both sides of the stope are both the original rock, the stability is good, and the stope safety can be ensured by adopting a support mode of an anchor rod net and a temporary wood upright column which is partially assisted; the anchor rod is in combined supporting with the metal mesh, the integrity and the stability of the top plate can be improved, and roof broken stones are effectively prevented from falling. At the same time, the metal net also connects a plurality of anchor rods together, and the stability of the top plate is increased in a larger range.

Because the rock itself steadiness is poor, the stoping operation security of the two-step pillar stope is worse after the stope of the one-step chamber stope is stoped and filled. And after the surrounding rock of the roof of the stope is exposed, the supporting is carried out, and due to the change of the stress distribution of the original rock, the movement, the relaxation, the expansion of joint cracks and the like of a single rock block are generated before the supporting, so that the bonding strength between the joint rock blocks is reduced.

Disclosure of Invention

The invention aims to provide a supporting method capable of greatly improving the overall stability of a two-step stope roof.

The two-step filling method support method provided by the invention is characterized in that when a one-step stope is used for stoping, anchor cables are constructed and installed in ore bodies of two-step stopes at two sides in a stope, and a two-step stope top plate is supported in advance.

In one embodiment of the above method, the construction and installation of the anchor cable includes the following steps:

(1) selection of anchor cable species

Selecting a non-prestressed anchor cable;

(2) anchor cable support parameter determination

The method comprises the steps of determining the diameter of an anchor cable, breaking force, the mesh degree of the anchor cable, the length of the anchor cable, the diameter of a drilled hole, the proportion of grouting materials and the direction of the drilled hole;

(3) drilling construction;

(4) installing an anchor cable;

(5) and (6) grouting.

In one embodiment of the above method, in the step (2), the diameter of the anchor cable is 14-30 mm, the breaking force is 100-450 kN, and the length is 5000-.

In one embodiment of the above method, in step (2), the mesh degree D of the anchor cable²Calculated as follows:

s represents the area of the construction anchor cable, and n represents the number of the anchor cables arranged in a unit area;

the arrangement number n of the anchor cables in a unit area is determined by the following formula:

m represents a safety factor; r-breaking tension of the steel wire rope.

In one embodiment of the method, in the step (2), the anchor cable hole construction is respectively performed on rock drilling in the stope in the adjacent step, the anchor cable holes are arranged on two sides in a staggered mode to form cross-mesh anchoring, and the diameter of the drilled hole is 50-90 mm.

In one embodiment of the above method, in step (2), the horizontal distance x the vertical distance of the single-side anchor cable mesh is calculated according to the actual situation of the stability of the ore rock in the use site.

In one embodiment of the above method, in the step (2), the slurry is injected by pure cement slurry, and the water-cement ratio is 0.65-0.80.

In one embodiment of the above method, in the step (2), upward inclined drilling is adopted, and the inclination angle of the drilling hole is 40-60 degrees.

In one embodiment of the above method, in the step (3), the drilling equipment is an anchor cable jumbo or a medium-length hole/deep-hole rock drill.

In one embodiment of the above method, the step (4) comprises the steps of:

(1) preliminary preparation work

Performing oil stain treatment on the surface of the anchor cable and straightness treatment on the anchor cable, and manufacturing a barb at the head of the anchor cable for fixing a grouting pipe; cutting and binding the length of the anchor cable, wherein the length of the anchor cable is larger than the length of the anchor cable hole by 300-400mm, and conveying the anchor cable to a construction site after sleeving a protective sleeve on the anchoring section;

(2) on-site construction

Binding equal-length exhaust pipes on one side of the anchor cable, blowing the anchor cable hole clean, and sending the anchoring end of the anchor cable to the bottom of the anchor cable hole by using an anchor cable machine;

placing a pressure-resistant steel pipe on one side of the anchor cable body at the orifice as a grouting pipe, sending the grouting pipe into the hole for 300-300 mm, sealing the exhaust pipe by using a wood plug after the exhaust pipe is led out from the orifice, wherein the length of the seal is 250-300 mm, the anchor cable and the grouting pipe are exposed for 200-300mm, and fixing the anchor cable at the orifice;

then, injecting mortar in an outward-inward advancing mode, and installing a base plate and an anchorage device to stretch the anchor cable at the exposed end of the anchor cable after the cement mortar is solidified for 48 hours;

and after grouting of all the anchor cable holes is completed and the grouting is fully performed with the concrete, tensioning and locking each anchor cable by using the cable clamp to form the anchor cable fixing net.

When the stope is stoped in the first step, anchor cables are constructed and installed in ore bodies on two sides in the stope, and the stope top plate in the second step is supported in advance. Specifically, rock drilling is respectively carried out in the ore body anchor cable construction of the two steps from the mining fields of the adjacent steps, anchor cable holes are arranged on two sides in a staggered mode, and cross mesh anchoring is formed. Through the suspension effect, the combination beam effect and the extrusion reinforcement effect of anchor rope, make frictional resistance and bending strength increase between the broken unstable rock stratum, increased its stability, broken area rock mass extrudees each other around every anchor rope simultaneously, forms the continuous even compression area that has certain thickness, can not only maintain self-stability, has bearing capacity moreover. And meanwhile, the slurry is filled into joints and cracks of the top plate rock stratum, so that the mechanical property of a structural surface is improved, the self-bearing capacity of a broken rock body is improved, the further deformation of the rock body is timely controlled, the sliding, the caving and the instability of rock blocks are prevented, and the stability of the top plate is maintained.

Drawings

Fig. 1 is a schematic view of the anchor cable support in a two-step stope according to an embodiment of the present invention.

Fig. 2 is a schematic view a-a in fig. 1.

FIG. 3 is a schematic view of B-B in FIG. 1.

Fig. 4 is a schematic view of the stress condition of the roof of the stope in the second step of the present embodiment.

Fig. 5 is a schematic structural view of the cork used in the present embodiment.

Detailed Description

The main innovation of the invention is that when the stope of the one-step stope is adopted, long anchor cables are constructed and installed in the ore body of the two-step stope from the inner side of the stope to the two sides, and the top plate of the two-step stope is supported in advance, so that the top plate of the two-step stope is anchored in advance through the long anchor cables in the original rock stress state, and the integral stability of the top plate of the two-step stope is greatly improved. Of course, in two-step stopes, locally unstable locations need to be supported by anchor nets or wood columns.

The one-step stope span of this example is 8m, and the two-step stope span is 7 m.

As can be seen from fig. 1 to 4, the two-step filling method disclosed in this embodiment includes the following steps:

one-step and one-step stope support

According to the principle of anchor bolt support action and by combining the actual conditions of various mines, as the mortar anchor rod cannot be immediately loaded after being installed and the pipe seam type anchor rod can be immediately loaded after being installed, the upper plate of the mine is broken, the exposure time of the top plate is not too long, the pipe seam type anchor rod is adopted, and the specific anchor rod net support parameters are as follows.

(1) Length of anchor rod

The length of the anchor rod used for roof support in one step is 1.2-3 m, generally 1.5-2 m, similar to that of domestic and foreign mines. Calculating the length L of the anchor rod by adopting an empirical formula:

in the formula: l-anchor length, L is more than two times of rock joint spacing, and the unit is meter;

n-rock formation stability influence coefficient, where the unstable N of ore body and rock is 1.2;

b-stope span, B being 8 meters;

substituting data, calculate: l2.28 m.

Thus, the design determines a stope bolt length of 2.4 meters.

(2) Spacing of anchor rods

The reasonable anchor rod spacing should satisfy the following two conditions: firstly, forming a continuous extrusion belt on the crushed rock body in the anchor rod supporting range; and secondly, each anchor rod can suspend the mass of the loosened rock mass within the supporting range.

The empirical calculation formula of the anchor rod spacing used in domestic and foreign mines is as follows:

α＝(0.5～0.7)L

in the formula: alpha-anchor rod spacing, alpha < triple rock joint spacing, in meters;

l is the length of the anchor rod, and the unit is meter.

Substituting data to calculate: alpha 1.2 m

Therefore, the design determines that the length of the anchor rod adopted by the stope is 2.4 meters, and the reasonable supporting mesh degree is calculated to be 1.1-1.3 meters multiplied by 1.1-1.3 meters.

Diameter of anchor rod

The diameter of the anchor rod used in domestic and foreign mines is 12-40 mm, and the diameter of the anchor rod is related to the type of the anchor rod. The diameter of the pipe seam type anchor rod is generally 30-43 mm, and the diameter of the anchor rod is 43mm according to design recommendation.

Other parameters

The metal net is woven with iron wire, and the net thickness is 50mm × 50 mm.

In order to ensure the installation quality of the anchor rod and exert the anchoring effect, the diameter of the drilled hole must meet the requirement. When the anchor rod is installed, the difficulty degree of the installation of the anchor rod is noticed, and the diameter of the drilled hole is adjusted according to the difficulty degree. When local instability occurs after the anchor rod net is used for supporting, temporary wood columns can be used for supporting in a stope.

Two-step and two-step stope support

(1) Long anchor cable species selection

The long cable bolts 1 are of many kinds and forms. According to different anchoring objects and purposes and different stress states, the structural forms and requirements of the anchor cables are different. Generally, the anchor cable can be divided into two types according to the stress state of the anchor cable: one is a prestressed anchorage cable, and the other is a non-prestressed anchorage cable.

The anchoring object of the embodiment is a roof of a stope in two steps, rocks are broken, the anchoring stress of the anchor cables is mainly large radial pressure and supporting capacity, so that the roof is prevented from falling off during stoping in two steps, the roof of the stope after being reinforced is temporary engineering and is not permanent engineering, and therefore the roof of the stope in two steps is reinforced by non-prestressed anchor cables.

(2) Anchor cable support parameter determination

The anchor cables are used for reinforcing the top ore rocks, and according to the condition of the ore rocks, only the top ore rocks of the stope are locally arranged when needing to be reinforced, the whole top ore rocks are comprehensively arranged when needing to be reinforced, and single (or a few) points can be arranged when only individual loose blocks need to be reinforced.

Because the two sides of the stope are the filling bodies of the stope in one step during the stope in the two steps, the stress environment of the stope in the two steps is worsened, the stability of ore rocks is poor, the hanging wall of the ore body is broken, and therefore long anchor cables need to be arranged comprehensively to reinforce the whole roof ore rocks of the stope in the two steps. The stress condition of the stope roof in the two steps is shown in figure 4.

As can be seen by combining fig. 1 and 4, the one-step stope of the present embodiment is about 10 meters in three tiers from the two-step stope. During the second-step mining, the stress of three layers in the top plate mainly comprises self ore rock dead weight G, friction force F of filling bodies on two sides to the top plate in the second step, self adhesive force C of the ore rock and supporting force F of upper and lower original rocks of the stope to the top plate. Because the frictional force F of the filling bodies on the two sides is small, the stope is large in length, and the supporting effect of the upper and lower tray ends of the stope on the stope top plate is limited, so that the frictional force F and the supporting force F of the upper and lower tray original rocks on the top plate are ignored in the actual supporting design of the top plate in the two steps, the self-weight G of the top plate rocks and the self-adhesive force C of the ore rocks are mainly considered, and the force P acting on the designed long anchor cable is the self-weight G of the top plate rocks minus the self-adhesive force C of the ore rocks, and the method specifically comprises the following steps:

P＝a·l·h·γ-c·a·l

in the formula: a-stope width, a being 7 m;

l-stope length, l is 50 meters;

h-loosening height, h is 10 m;

gamma-ore body weight, gamma 2.75t/m³；

c-adhesion, c 2.35MPa 2.35X 10⁶N/m²；；

The total pressure acting on the anchor cable was calculated to be 14000kN by taking the data in.

(2.1) wire rope diameter

The diameter of a steel wire rope is generally 14-30 mm when a long anchor cable is reinforced, and the breaking force is 100-450 KN. The selection is usually made according to the breaking force of the steel wire rope required by the anchoring and the external surface area of the steel wire rope. When the old steel wire rope is selected, the diameter of the steel wire rope should be selected to be larger. Similar to the similar engineering design at home and abroad, the diameter of the steel wire rope is selected to be phi 14 mm.

(2.2) mesh length of long anchor cable

The mesh degree of the long anchor cables is selected according to the stability of the rock stratum and the development degree of the joint cracks. Unstable rock stratum, joint fracture relatively develop, the net degree is 1.5 meters multiplied by 1.5 meters or 2 meters multiplied by 2 meters generally; the stable rock stratum has better integrity and the net degree is 3 meters multiplied by 3 meters or 4 meters multiplied by 4 meters.

The anchor rope of this embodiment is installed in stope roof plate rock stratum, mainly through its resistance to compression, shearing ability restriction rock mass displacement, the inside stress field of adjustment rock stratum to and make roof country rock in time form the effect of complete firm rock mass, consequently anchor rope radical n is in the unit area:

in the formula: m is a safety factor, and m is 1.2;

r is the breaking tension of the steel wire rope, and R is 120 KN;

net degree of anchor cable D²：

In the formula: s-area of construction anchor cable, S is 2 × 10 × 50 is 1000 m²；

The number n of anchor cables is 140, and the net degree D of the anchor cables is calculated by the data²7.14 m²Namely, the supporting area borne by one long anchor cable is 7.14 meters². When stope stoping is carried out, the layered stoping height and the filling height are both 3.3 meters, and for facilitating anchor cable drilling and installation, the interlayer height of a long anchor cable support is determined to be 3.3 meters, the hole spacing is 2.1 meters, namely the mesh size of the anchor cable is 3.3 meters multiplied by 2.1 meters.

However, in order to further improve the anchor cable support strength and enable each anchor cable to be stressed uniformly, in this embodiment, rock drilling is performed on the ore body anchor cable construction in the two steps from the mining fields in the adjacent steps, and anchor cable holes are arranged in a staggered mode on two sides to form cross mesh anchoring. Therefore, the hole pitch of the single-side anchor cable is 4.0 meters, the interlayer spacing is 3.3 meters, namely the mesh degree of the single-side anchor cable is 3.3 meters multiplied by 4.0 meters.

Because the stability of the upper wall of the ore body is poor, the stability of the lower wall is slightly better than that of the upper wall, when the anchor cables are supported, the mesh degree of the anchor cables of the lower wall can be properly increased, and the mesh degree of the anchor cables of the upper wall is properly reduced, the mesh degree of the long anchor cables on the single side of the stope in the first step is recommended to be 3.0 meters multiplied by 3.3 meters to 5.0 meters multiplied by 3.3 meters (horizontal distance multiplied by vertical distance); namely, the stability of the ore body lower wall is good, the ore body lower wall is supported by the lower wall surrounding rock, and the mesh size of 5.0 m multiplied by 3.3 m is adopted from the lower wall to the upper wall of the stope at the position of 10 m; the ore body is positioned in a weak section with a stress structure towards the middle, and the section from the lower wall to the upper wall of the stope is 10-35 m in mesh size of 4.0 m multiplied by 3.3 m; the stability of the ore body on which 15 m ore rocks are hung is poor, and the mesh degree of 3.0 m multiplied by 3.3 m is adopted. The parameters of the anchor cable hole network of the stope in the second step are shown in figures 1-3.

(2.3) Anchor rope Length

In general, the long anchor cable is a steel cable, and the length of the long anchor cable is about 5 meters to 50 meters. When in use, the method is determined according to the following two principles under the conditions of perforation equipment, a rope feeding mode and a grouting mode according to specific conditions: starting from the combination and suspension effects of the long anchor cables, the length of the long anchor cables is larger than the maximum possible caving height of a stope roof, and the drilling length is lengthened as much as possible under the conditions of drilling equipment and convenient installation; according to the principle of equal strength, the load borne by the anchor cable is equal to the mortar bonding force.

The recommended long anchor cable drilling equipment is an Atlas boom K41X drill jumbo, the mining field width in the two steps is 7 meters, the angle of the anchor cable hole is 40-60 degrees, and the hole depth is 8.5-11 meters.

(2.4) borehole diameter

The diameter of the drilled hole not only needs to meet the requirement of convenient installation of the steel wire rope, the exhaust pipe and the grouting pipe, but also needs to enable the bonding strength of the steel wire rope and mortar and the bonding strength of the mortar and the hole wall to reach the optimal value. The drilling method is generally selected according to experience and similar projects at home and abroad, and the commonly used drilling diameter is 50-90 mm. In this embodiment, an Atlas Boomer K41X drill jumbo is used to drill long anchor line boreholes with a diameter of 65 mm.

(2.5) slip casting mix ratio

The pure cement slurry is adopted, the water-cement ratio is 0.65-0.80, and the anchoring requirement of the anchor cable can be met.

(2.6) drilling direction

The anchor cable holes in the stope are drilled obliquely upwards, the inclination angle of the drilled holes is 40-60 degrees, and the azimuth angle is determined according to the inclination angle of a structural plane and a structural belt.

(3) Drilling construction

When the stope is pushed forward by about 30 meters in one step, the stope can enter the stope to construct anchor cable drill holes, and the anchor cable drill holes and stope rock drilling can be carried out simultaneously.

The anchor cable hole drilling adopts an Atlas Boomer K41X rock drilling trolley, the anchor cable hole depth is 8.5-11 meters, the drilling diameter is 65mm, and the drilling inclination angle is 40-60 degrees. And (3) drilling holes from two sides of the stope in the first step to the ore rocks in the second step, so that the net height of the drilled holes on one side is 3 meters multiplied by 3.3 meters to 5 meters multiplied by 3.3 meters, wherein the net height of the anchor cables close to the lower disc is 5 meters multiplied by 3.3 meters, and the net height of the anchor cables close to the upper disc is 3 meters multiplied by 3.3 meters.

The construction is carried out according to the following requirements during drilling:

knocking the help and asking the top, checking surrounding rocks and supporting conditions of a construction site, and ensuring safe operation;

determining an eye position according to the design position requirement of the anchor cable hole, and marking;

checking and preparing a drilling machine and a drilling tool, and connecting a wind-water pipeline;

fourthly, after the initial drill rod is in place, disconnecting the drill rod, connecting the next drill rod by using a connector, and so on until the drilling is finished, and sequentially detaching the drill rods;

after drilling, the wind pipe is removed, and the drilling machine is placed at a designated place.

(4) Anchor cable installation

After the anchor cable hole is drilled, the anchor cable is installed according to the following requirements:

when a newly bought steel wire rope is used, a layer of smooth protective oil is plated on the surface of the newly bought steel wire rope, and the steel wire rope is extremely smooth and small in friction force. Before the long anchor cable is manufactured, the protective oil on the surface of the steel wire rope is removed by adopting a distillation method, so that the phenomenon that the adhesive force between the steel wire rope and mortar is reduced due to the existence of the protective oil is avoided. When the waste steel wire rope is lifted in a mine, the steel wire rope can be put in fire for processing in order to enable the steel wire rope to be spiral and remove oil stains on the surface. And (3) bending the barb at the head of the anchor cable, inserting the grouting pipe into the barb during installation, and then feeding the grouting pipe and the steel wire rope into the bottom of the hole together.

Secondly, cutting the steel strands according to the designed length and binding the steel strands by using a grinding wheel cutting machine or an anchor cable shearing device on the ground surface, and transporting the steel strands to a construction site, wherein in order to prevent the steel strands from scattering, a plastic pipe with the size of 100mm is sleeved at the anchoring end according to the size of the steel strands for protection.

Blowing the anchor cable hole completely by using high-pressure air on site, and manually feeding the steel strand into the anchor cable hole; adopting forward mortar injection from outside to inside, fixing a polyvinyl chloride exhaust pipe with the diameter of 8mm on a steel strand by using an adhesive tape, simultaneously feeding a steel wire rope and one end of a polyvinyl chloride exhaust hose into the bottom of a hole, and respectively keeping 300mm outside the hole opening so as to stretch an anchor rope and install an anchorage device and a base plate.

Placing a grouting pipe (pressure-resistant steel pipe) with the diameter of 25mm multiplied by 600mm on one side of the anchor cable body at the orifice, feeding the grouting pipe into the hole for 300mm, leading the exhaust pipe out of the orifice, sealing a special wooden plug, wherein the sealing length is 250-300 mm, and the grouting pipe is exposed for 200 mm; in an up or inclined hole, the steel strands must be secured to the opening by a wooden wedge in order to prevent the rope from sliding out of the hole. The structure of the sealing wooden plug is shown in figure 5.

Fifthly, after grouting, mounting the backing plate and the anchorage device after cement mortar is solidified for 48 hours. The anchor cable is stretched by using the anchor cable stretching jack, the anchor device is required to be pressed against the backing plate and tightly attached to the rock surface, and the anchor device locking plate is required to be locked, so that the anchor device is prevented from sliding along the anchor cable due to failure of the anchor device after the anchor cable is stressed.

(5) Grouting

The method is carried out by adopting a forward grouting mode from outside to inside, namely, slurry is continuously pressed into the bottom of the hole from the hole opening, and compressed gas in the hole is discharged out of the hole through the exhaust pipe.

The grouting adopts pure cement slurry with the water cement ratio of 0.65-0.80, a QZB-50/60 type grouting pump is selected as the grouting pump, the grouting pressure is 2-5 Mpa, and the stirring of the cement slurry is carried out in a field stirring tank.

Air trapped in the hole escapes through the exhaust pipe, indicating that the slurry has filled the borehole when it exits the exhaust pipe.

And after grouting of each anchor cable hole is finished, after the grouting is fully solidified, tightening and locking each anchor cable by using a cable clamp, so that the rows and the holes are mutually connected, and the aim of integrally anchoring is fulfilled.

Briefly, the anchor cable construction cycle of this embodiment is as follows: transporting construction equipment to an underground site → cutting a steel strand on the ground surface, processing a base plate and transporting to the underground site → calibrating a hole site → aligning drilling of the hole site → adding a power drill rod, installing a connector → dismantling the drill rod and the connector after drilling → fixing an exhaust pipe on a long anchor rope and manually feeding the anchor rope into the hole → installing a grouting pipe and sealing with a wood plug → grouting → cutting off the exposed grouting pipe after 48 hours to install the base plate, and stretching the anchor rope to press the base plate.