CN112459058A - Echelon pressurizing grouting anchor rod and construction method thereof - Google Patents

Abstract

The invention discloses a echelon pressurizing grouting anchor rod and a construction method thereof, wherein the echelon pressurizing grouting anchor rod comprises a grouting anchor rod, five layers of equidistant grouting holes are formed in the grouting anchor rod along the length direction of a rod body, one to five layers of grouting holes are sequentially formed from the head part to the tail part of the grouting anchor rod, a first layer of rubber check ring is distributed on the inner wall of the grouting anchor rod at the position of the first layer of grouting holes and at the position of half layer distance away from the tail part of the rod body of the grouting anchor rod, four rubber check rings are sequentially arranged on the grouting anchor rod and positioned at the rear part of the first layer of rubber check ring, and the distance between every two adjacent rubber check rings is the same as the distance between every two adjacent grouting holes. Has the advantages that: the device is simple and easy, and simple manufacture is high-efficient, the high-usage has higher and lasts the adhesion stress, can effectively enlarge the slip casting area, and reinforcing slip casting homogeneity and closely knit degree make the slip casting stock can with peripheral weak soil closely combine, can prevent that the stock from droing, have higher economic nature and suitability.

Description

Echelon pressurizing grouting anchor rod and construction method thereof

Technical Field

The invention relates to the technical field of echelon pressurized grouting anchor rods, in particular to a echelon pressurized grouting anchor rod and a construction method thereof.

Background

Along with the rapid development of economy, high-rise buildings and urban underground engineering are increased continuously, so that a large number of deep foundation pit excavation supporting engineering are generated, and in developed coastal areas of China, a large-range soft soil stratum is provided, the water content of a soil body is high, and the physical and mechanical properties are poor, so that the anchoring technology becomes more and more important;

most of the existing grouting anchor rods are formed by one-time grouting, the anchor rods formed by one-time grouting have the problems of insufficient later anchoring force and easiness in loosening, and are difficult to provide continuous anchoring force in soft soil, and most of the existing grouting anchor rods used in engineering are end grouting type, so that the grouting anchor rods are long in rod body, the problems of poor dispersivity, easiness in loosening after the process and the like of grouting liquid exist, and the occupied proportion of a grouting area is small;

chinese patent CN 206769935U discloses a top expansion grouting anchor rod, which comprises an anchor rod head, an anchor rod body, an anchor rod thread section, a tray, a grouting hole, a nut and an expansion reinforcing body; the anchor rod body is hollow cylinder, and inside cavity is the slip casting passageway, and the surface interval is equipped with the through-hole. The top end of the head of the anchor rod is provided with a circular truncated cone-shaped fastener, the thread section of the anchor rod penetrates through the anchor rod tray and is in threaded connection with the nut, the expansion reinforcing body is of a hollow structure, the inner diameter of the expansion reinforcing body is slightly smaller than that of the anchor rod head, when the expansion reinforcing body is extruded by the anchor rod head, the cylindrical fastener buckles the clamping groove of the expansion reinforcing body and causes the expansion reinforcing body to radially open, the contact friction resistance between the end part of the grouting anchor rod and the wall of the surrounding rock is increased, and the initial anchoring force of the grouting anchor rod at the initial anchoring stage is improved, but the method only has the expansion body at the top end of the anchor rod, the contact area between the expansion body and the soil;

chinese patent CN 105715287 a discloses a combined self-advancing grouting anchor rod, wherein the hollow grouting anchor rod body is divided into a front rod and a rear rod, a grouting channel is axially arranged inside, the outer surface of the front rod of the hollow grouting anchor rod body is provided with a barb-shaped thread anchoring section, the hollow grouting anchor rod body is connected with the rear rod of the hollow grouting anchor rod body through a combined connecting sleeve, an anchor head is installed at the end part of the front rod of the hollow grouting anchor rod body, a grouting port of the anchor head is the same as the grouting channel, and a plurality of grouting holes communicated with the grouting channel are radially processed on the hollow grouting anchor rod body. Through a plurality of grouting holes communicated with the grouting channel in the hollow grouting anchor rod body, grouting liquid is well combined with surrounding rock, and the anchoring force is increased, but the problem that insufficient pressure exists in each grouting hole during grouting cannot be solved, the grouting liquid cannot better permeate into the surrounding rock, and the anchoring effect is not optimal;

in order to make grouting as sufficient as possible, the grout should be bonded with the surrounding soil as much as possible, and the anchor rod and the soil body of the whole body are bonded together to provide the maximum anti-slip resistance, so it is necessary to design a stepped pressurized grouting anchor rod and a construction method thereof to solve the above problems.

Disclosure of Invention

The invention aims to solve the problems in the prior art and provides a gradient pressurized grouting anchor rod and a construction method thereof.

In order to achieve the purpose, the invention adopts the following technical scheme:

a echelon pressurizing grouting anchor rod and a construction method thereof comprise a grouting anchor rod, wherein five layers of equidistant grouting holes are formed in the grouting anchor rod along the length direction of a rod body, one to five layers are sequentially formed from the head part to the tail part of the grouting anchor rod, a first layer of rubber check ring is distributed on the inner wall of the grouting anchor rod at a position, away from the tail part of the rod body of the grouting anchor rod, of the first layer of grouting holes by half layer distance, four rubber check rings are sequentially arranged at the rear part, located at the first layer of rubber check ring, of the grouting anchor rod, and the distance between every two adjacent rubber check rings is the same as the distance between every two adjacent grouting holes;

the rubber check ring is bonded on the inner wall of the grouting anchor rod through a strong cementing agent ring and is inclined towards the head of the grouting anchor rod, each grouting anchor rod is connected with a grouting guide pipe through a small thread, the grouting guide pipe is provided with a pressurizing plate, and the grouting guide pipe can enter the grouting anchor rod under the pushing of manpower and reach the position of the head;

after the grouting anchor rod is inserted into a soil body, a grouting guide pipe is required to be inserted for grouting, the grouting guide pipe is of a hollow tubular structure, the diameter of the grouting guide pipe is smaller than the inner diameter of the grouting anchor rod, the pressurizing plate is positioned at the head of the grouting guide pipe and is circular, and the function of the pressurizing plate is that the grouting guide pipe is clamped on the rubber check ring to pressurize front grouting when grouting;

when the slip casting begins, the pressure plate on the slip casting pipe is in the front portion of first layer rubber check ring, and the pressure of thick liquid can make the pressure plate retreat to first layer rubber check ring, and first layer rubber check ring then can withstand the pressure plate, for it provides withdrawal resistance, carries out the pressurized grouting to the injected hole of slip casting stock head and the downthehole injection slip of first layer at this moment, and after the interior thick liquid pressure of slip casting stock exceeded the resistance that rubber check ring can provide, the pressure plate broke first layer rubber check ring and retreat to next stage rubber check ring department.

In the above-mentioned a echelon pressurization slip casting stock, the rubber check ring becomes thick gradually from the head to the afterbody of slip casting stock, and the corresponding grow of resistance that provides to deal with the increase of the slip casting hole quantity of its burden of each back one deck of pressure plate, need bigger pressure to guarantee each slip casting hole and continue to pressurize.

In the echelon pressurized grouting anchor rod, the rubber check ring is made of hard rubber and is in an inclined shape towards the head of the rod body, so that the resistance required by pushing the grouting guide pipe is far smaller than the withdrawal resistance of the grouting guide pipe, and workers can conveniently push the grouting guide pipe into the grouting anchor rod manually;

five-layer rubber check rings are arranged, five-stage gradual pressurization can be provided, the maximum pressure is set to be 20MPa, one layer of rubber check ring can provide 80% of the maximum pressure, and then 5% of pressure is added to each layer until the fifth layer reaches 100% of the maximum pressure. If meeting special construction requirement when bigger slip casting pressure, can increase the slip casting pressure value by increasing the thickness of rubber check ring as appropriate.

In the echelon pressurizing grouting anchor rod, the tail part of the grouting guide pipe 6 is connected with the adapter sleeve through threads, and the adapter sleeve is used for connecting the grouting guide pipe with the grouting pipe, so that the sealing performance of the grouting guide pipe during grouting is ensured, and the problem that the calibers of the grouting anchor rod and the grouting guide pipe are not consistent is solved; the tail of the grouting anchor rod is provided with threads which can be directly connected with a grouting pipe, the threads are 5-7 circles, the tightness is guaranteed after the grouting anchor rod is screwed on, and grout is prevented from flowing out. And after the grouting guide pipe completes echelon pressurized grouting, taking out the grouting guide pipe, and directly connecting the tail part of the grouting anchor rod with the grouting pipe through threads to perform primary grouting supplement.

In the above-mentioned one kind of pressurization slip casting stock, the pressure plate diameter is adjusted according to the slip casting stock diameter corresponding, and the diameter is less than about 3mm of slip casting stock internal diameter.

In the echelon pressurizing grouting anchor rod, the tail part of the grouting guide pipe is provided with a red mark, the grouting guide pipe is withdrawn to the position of the fourth layer of rubber check ring, the red mark is displayed on the exposed grouting guide pipe, and a constructor is prompted to pay attention to stopping grouting in time.

A construction method of a echelon pressurized grouting anchor rod comprises the following steps:

1) prefabricating a grouting anchor rod and a grouting guide pipe, determining the construction position of the grouting anchor rod on the surface of a soil layer by using a measuring tool, drilling a hole required by excavating the grouting anchor rod and cleaning the hole;

2) placing a grouting anchor rod into the construction hole, pushing the grouting guide pipe into the grouting anchor rod body, and pushing the grouting guide pipe layer by layer to enable the pressurizing plate to reach the head of the grouting anchor rod; connecting the grouting guide pipe with the grouting pipe through the adapter sleeve, then opening grouting, and when the grouting guide pipe is withdrawn to the last layer of rubber check ring, preparing to stop grouting and take down the grouting pipe to complete echelon grouting;

3) and (4) after the echelon grouting is finished, the soft soil can absorb part of grout, so that grout is supplemented. And after the echelon grouting of the grouting anchor rod is finished, taking out the grouting guide pipe, and then directly connecting the grouting anchor rod with the grouting pipe at an interval of six to eight minutes to perform grouting supplement and finish grouting construction.

4) And (3) drilling grouting anchor rods on other surfaces needing construction according to the sequence of the steps 1) to 3), and taking out the grouting guide pipes for recycling after each step of pressurized grouting is finished.

In the step 2), the echelon pressurized grouting time of each grouting anchor rod is controlled within three minutes, so that the initial setting time requirement of the quick setting mortar is met.

In the step 2), when the pressurizing plate reaches the fourth layer of rubber check ring in the grouting process, the red mark is exposed at the tail of the grouting guide pipe to remind an operator that grouting is about to be completed, and the grouting guide pipe is prepared to be dismounted in time.

In the step 3), according to the characteristics of the loose soil body, the soil body finishes more than 85% of the slurry absorption in about eight minutes, and the subsequent absorption is slight, so the replenishment is carried out at the moment.

Compared with the prior art, the invention has the advantages that:

1: the invention provides resistance for the withdrawal of the grouting guide pipe by arranging the rubber check ring on the inner wall of the grouting anchor rod, so that the grouting hole is pressurized and grouted. Each layer of grouting holes are fully grouted under stepped pressurization and are fully combined with the surrounding soil body, the slurry dispersion area is increased, continuous bonding force is provided, and the later slippage and loosening of the anchor rod are prevented.

2: the grouting guide pipe retreating step by step is also a mark of grouting proceeding degree, so that the front part is ensured to obtain enough pressure, and constructors are reminded to pull out the grouting pipe in time.

3: after the pressure grouting is finished each time, the grouting guide pipe can be taken out for recycling, so that the material utilization rate is improved; the screw thread of the tail part of the grouting anchor rod can be directly connected with the grouting pipe and can also be connected with the grout stop plug, so that the structure is simplified.

In conclusion, the grouting anchor rod is simple and easy to manufacture, high in utilization rate, high in continuous bonding force, capable of effectively enlarging the grouting area, enhancing the grouting uniformity and compactness, capable of enabling the grouting anchor rod to be tightly combined with peripheral soft soil, capable of preventing the anchor rod from falling off, and high in economical efficiency and applicability.

Drawings

Fig. 1 is a side perspective view of a grouted anchor rod according to the present invention and a method for constructing the same;

FIG. 2 is a schematic view of a grouting conduit of the invention;

fig. 3 is a front view of the grout anchor of fig. 1 in accordance with the present invention;

FIG. 4 is a schematic structural view of the large thread of FIG. 1 and an adapter sleeve thereon;

fig. 5 is a use state diagram of the present invention.

In the figure: the grouting anchor rod comprises a grouting anchor rod 1, a rubber check ring 2, a grouting hole 3, a grout stop plug 4, a small thread 5, a grouting guide pipe 6, a pressurizing plate 7, an adapter sleeve 8, a red mark 9 and a large thread 10.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1-5, a echelon pressurizing grouting anchor rod comprises a grouting anchor rod 1, five layers of equidistant grouting holes 3 are formed in the grouting anchor rod 1 along the length direction of a rod body, one to five layers are sequentially formed from the head part to the tail part of the grouting anchor rod 1, a first layer of rubber check ring 2 is distributed on the inner wall of the grouting anchor rod 1 at a position of the first layer of grouting holes 3 and at a distance of half layer distance from the tail part of the rod body of the grouting anchor rod 1, four rubber check rings 2 are sequentially arranged on the grouting anchor rod 1 at the rear part of the first layer of rubber check ring 2, and the distance between every two adjacent rubber check rings 2 is the same as the distance between every two adjacent grouting holes 3;

the rubber check ring 2 is bonded on the inner wall of the grouting anchor rod 1 through a strong cementing agent ring and is inclined towards the head of the grouting anchor rod 1, each grouting anchor rod 1 is connected with a grouting guide pipe 6 through a small thread 5, the grouting guide pipe 6 is provided with a pressurizing plate 7, and the grouting guide pipe 6 can enter the grouting anchor rod 1 under the manual pushing action and reaches the head position;

after the grouting anchor rod 1 is inserted into a soil body, a grouting guide pipe 6 is required to be inserted for realizing grouting, the grouting guide pipe 6 is of a hollow tubular structure, the diameter of the grouting guide pipe 6 is smaller than the inner diameter of the grouting anchor rod 1, the pressurizing plate 7 is positioned at the head of the grouting guide pipe 6, the pressurizing plate 7 is circular, and the function is that the grouting guide pipe 6 is clamped on the rubber check ring 2 to pressurize front grouting when grouting;

when grouting is started, the pressurizing plate 7 on the grouting guide pipe 6 is positioned in front of the first layer of rubber check ring 2, the pressure of grout can enable the pressurizing plate 7 to retreat to the first layer of rubber check ring 2, the first layer of rubber check ring 2 can prop against the pressurizing plate 7 to provide withdrawal resistance for the pressurizing plate 7, pressurized grouting is conducted in the grouting hole 3 in the head of the grouting anchor rod 1 and the first layer of grouting hole 3, and after the pressure of the grout in the grouting anchor rod 1 exceeds the resistance which can be provided by the rubber check ring 2, the pressurizing plate 7 breaks through the first layer of rubber check ring 2 and retreats to the next layer of rubber check ring 2;

the rubber check ring 2 gradually thickens from the head to the tail of the grouting anchor rod 1, the provided resistance is correspondingly increased, so that the number of the grouting holes 3 borne by the pressurizing plate 7 is increased when the pressurizing plate moves back by one layer, and higher pressure is needed to ensure that each grouting hole 3 is continuously pressurized;

the rubber check ring 2 is made of hard rubber and is in an inclined shape towards the head of the rod body, so that the resistance required for pushing the grouting guide pipe 6 into the grouting guide pipe 6 is far less than the withdrawing resistance of the grouting guide pipe 6, and workers can conveniently and manually push the grouting guide pipe 6 into the grouting anchor rod 1;

five layers of rubber check rings 2 are arranged, five-stage gradual pressurization can be provided, the maximum pressure is set to be 20MPa, one layer of rubber check ring 2 can provide 80% of the maximum pressure, and then 5% of pressure is added to each layer until the fifth layer reaches 100% of the maximum pressure. If meeting the special construction requirement and having larger grouting pressure, the thickness of the rubber check ring 2 can be increased as appropriate to increase the grouting pressure value

The tail part of the grouting guide pipe 6 is connected with an adapter sleeve 8 through threads, the adapter sleeve 8 is used for connecting the grouting guide pipe 6 with a grouting pipe, the sealing performance of the grouting guide pipe 6 during grouting is guaranteed, and the problem that the calibers of the grouting anchor rod 1 and the grouting guide pipe 6 are not consistent is solved; the tail of the grouting anchor rod 1 is provided with threads which can be directly connected with a grouting pipe, the threads are 5-7 circles, the tightness is guaranteed after the grouting anchor rod is screwed on, and grout is prevented from flowing out. After the grouting guide pipe 6 completes echelon pressurized grouting, taking out the grouting guide pipe 6, and enabling the tail part of the grouting anchor rod 1 to be directly connected with a grouting pipe through threads to perform primary grouting supplement;

the diameter of the pressurizing plate 7 is correspondingly adjusted according to the diameter of the grouting anchor rod 1, and the diameter is about 3mm smaller than the inner diameter of the grouting anchor rod 1

The tail of the grouting guide pipe 6 is provided with a red mark 9, the grouting guide pipe 6 is withdrawn to the fourth layer of rubber check ring 2, the red mark 9 is displayed on the grouting guide pipe 6 exposed outside, and a constructor is prompted to pay attention to stopping grouting in time.

A construction method of a echelon pressurized grouting anchor rod comprises the following steps:

1) prefabricating a grouting anchor rod 1 and a grouting guide pipe 6, determining the construction position of the grouting anchor rod 1 on the surface of a soil layer by using a measuring tool, drilling and excavating a hole required for construction of the grouting anchor rod 1 and cleaning the hole;

2) placing the grouting anchor rod 1 into a construction hole, pushing the grouting guide pipe 6 into the grouting anchor rod 1, and pushing layer by layer to enable the pressurizing plate 7 to reach the head of the grouting anchor rod 1; connecting the grouting guide pipe 6 with a grouting pipe through the adapter sleeve 8, then opening grouting, and preparing to stop grouting and take down the grouting pipe when the grouting guide pipe 6 is withdrawn to the last layer of rubber check ring 2 to complete echelon grouting;

3) and (4) after the echelon grouting is finished, the soft soil can absorb part of grout, so that grout is supplemented. After the echelon grouting of the grouting anchor rod 1 is completed, the grouting guide pipe 6 is taken out and then is directly connected with a grouting pipe at an interval of six to eight minutes, and grouting is performed to complete grouting construction.

4) And (3) drilling grouting anchor rods 1 on other surfaces needing construction according to the sequence of the steps 1) to 3), and taking out the grouting guide pipes 6 for recycling after each echelon pressurization grouting is finished.

In the step 2), the echelon pressurizing grouting time of each grouting anchor rod 1 is controlled within three minutes, and the initial setting time requirement of the quick setting mortar is met.

In the step 2), in the grouting process, when the pressurizing plate 7 reaches the fourth layer of rubber check ring 2, the red mark 9 is exposed at the tail part of the grouting guide pipe 6, so that an operator is reminded of finishing grouting and the grouting guide pipe 6 is prepared to be dismounted in time.

In the step 3), according to the characteristics of the loose soil body, the soil body finishes more than 85% of the slurry absorption in about eight minutes, the subsequent absorption is slight, and therefore slurry supplement is carried out at the moment.

Further, unless otherwise specifically stated or limited, the above-described fixed connection is to be understood in a broad sense, and may be, for example, welded, glued, or integrally formed as is conventional in the art.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims (7)

1. The utility model provides a echelon pressurization slip casting stock, includes slip casting stock (1), its characterized in that, be provided with five layers of equidistance slip casting holes (3) along body of rod length direction on slip casting stock (1), and be one by slip casting stock (1) head to the afterbody in proper order five layers, first layer slip casting hole (3) position has laid first layer rubber check ring (2) to the slip casting stock (1) inner wall of half layer distance department of slip casting stock (1) body of rod afterbody direction distance, the rear portion that lies in first layer rubber check ring (2) on slip casting stock (1) has set gradually four rubber check ring (2), and the interval between every two adjacent rubber check ring (2) is the same with the interval between every two adjacent slip casting hole (3);

the rubber check ring (2) is bonded on the inner wall of the grouting anchor rod (1) through a strong cementing agent ring and is inclined towards the head of the grouting anchor rod (1), each grouting anchor rod (1) is connected with a grouting guide pipe (6) through a small thread (5), a pressurizing plate (7) is arranged on each grouting guide pipe (6), and each grouting guide pipe (6) can enter the grouting anchor rod (1) under the manual pushing action and reaches the head;

after the grouting anchor rod (1) is inserted into a soil body, grouting needs to be achieved by inserting a grouting guide pipe (6), the grouting guide pipe (6) is of a hollow tubular structure, the diameter of the grouting guide pipe is smaller than the inner diameter of the grouting anchor rod (1), a pressurizing plate (7) is located at the head of the grouting guide pipe (6), the pressurizing plate (7) is circular, and the effect is that the grouting guide pipe (6) is clamped on a rubber check ring (2) to pressurize front grouting when grouting;

when grouting is started, a pressurizing plate (7) on a grouting guide pipe (6) is arranged in the front of a first layer of rubber check ring (2), the pressurizing plate (7) can be retreated to the first layer of rubber check ring (2) under the pressure of grout, the pressurizing plate (7) can be propped against the first layer of rubber check ring (2) to provide withdrawal resistance for the first layer of rubber check ring (2), at the moment, pressurized grouting is carried out in a grouting hole (3) at the head of a grouting anchor rod (1) and the first layer of grouting hole (3), and after the pressure of the grout in the grouting anchor rod (1) exceeds the resistance which can be provided by the rubber check ring (2), the pressurizing plate (7) breaks through the first layer of rubber check ring (2) and retreats to the next layer of rubber check ring (2).

2. A stepped pressure grouting anchor according to claim 1, characterised in that the rubber check ring (2) becomes thicker gradually from the head to the tail of the grouting anchor (1), providing correspondingly greater resistance to cope with the increased number of grouting holes (3) per each receding layer of the pressure plate (7), requiring greater pressure to ensure continuous pressurization of each grouting hole (3).

3. The echelon pressurizing grouting anchor rod as claimed in claim 1, wherein the rubber check ring (2) is made of hard rubber and is shaped like a slope towards the head of the rod body, so that the resistance required for pushing the grouting guide pipe (6) is far less than the withdrawal resistance of the grouting guide pipe (6), and workers can conveniently push the grouting guide pipe (6) into the grouting anchor rod (1) manually;

the five layers of rubber check rings (2) are arranged, five-stage gradual pressurization can be provided, the maximum pressure is set to be 20MPa, one layer of rubber check ring (2) can provide 80% of the maximum pressure, and then the pressure of each layer is increased by 5% until the fifth layer reaches 100% of the maximum pressure;

if meeting the special construction and needing bigger grouting pressure, can increase the thickness of the rubber check ring (2) as appropriate to increase the grouting pressure value.

4. The echelon pressurizing grouting anchor rod as claimed in claim 1, wherein the tail part of the grouting guide pipe (6) is connected with an adapter sleeve (8) through threads, and the adapter sleeve (8) is used for connecting the grouting guide pipe (6) with a grouting pipe, so that the sealing performance of the grouting guide pipe (6) during grouting is ensured, and the problem of inconsistent calibers of the grouting anchor rod (1) and the grouting guide pipe (6) is solved; the tail of the grouting anchor rod (1) is provided with threads which can be directly connected with a grouting pipe, the number of the threads is 5-7, and the threads are screwed up to ensure the sealing property and prevent grout from flowing out;

after the grouting guide pipe (6) completes echelon pressurized grouting, the grouting guide pipe (6) is taken out, so that the tail part of the grouting anchor rod (1) is directly connected with the grouting pipe through threads to perform primary grouting supplement.

5. A stepped pressure grouting anchor according to claim 1, characterized in that the diameter of the pressure plate (7) is adjusted accordingly to the diameter of the grouting anchor (1) and is about 3mm smaller than the inner diameter of the grouting anchor (1).

6. The echelon pressurizing grouting anchor rod as claimed in claim 1, wherein a red mark (9) is arranged at the tail of the grouting guide pipe (6), the grouting guide pipe (6) is withdrawn to the fourth layer of rubber check ring (2), and the red mark (9) is displayed on the grouting guide pipe (6) exposed outside to prompt a constructor to pay attention to stopping grouting in time.

7. The construction method of the echelon pressurized grouting anchor rod is characterized by comprising the following steps of:

1) prefabricating a grouting anchor rod (1) and a grouting guide pipe (6), determining the construction position of the grouting anchor rod (1) on the surface of a soil layer by using a measuring tool, drilling and excavating holes required for construction of the grouting anchor rod (1) and cleaning the holes;

2) placing the grouting anchor rod (1) body into a construction hole, pushing the grouting guide pipe (6) into the grouting anchor rod (1), and pushing layer by layer to enable the pressurizing plate (7) to reach the head of the grouting anchor rod (1); connecting the grouting guide pipe (6) with a grouting pipe through a switching sleeve (8), then opening grouting, and preparing to stop grouting and take down the grouting pipe when the grouting guide pipe (6) is withdrawn to the last layer of rubber check ring (2) to complete echelon grouting;

3) considering that the soft soil can absorb part of slurry after the echelon grouting is finished, so the slurry is supplemented;

after the echelon grouting of the grouting anchor rod (1) is finished, taking out the grouting guide pipe (6), and then separating for six to eight minutes, directly connecting the grouting anchor rod (1) with the grouting pipe for grouting supplement, and finishing grouting construction;

4) grouting anchor rods (1) on other surfaces needing construction according to the sequence of the steps 1) to 3), and taking out the grouting guide pipes (6) for recycling after each step of pressurized grouting;

in the step 2), the echelon pressurized grouting time of each grouting anchor rod (1) is controlled within three minutes, so that the initial setting time requirement of the quick setting mortar is met;

in the step 2), when the pressurizing plate (7) reaches the fourth layer of rubber check ring (2) in the grouting process, a red mark (9) is exposed at the tail of the grouting guide pipe (6) to remind an operator that grouting is about to be completed, and the grouting guide pipe (6) is prepared to be dismounted in time;

in the step 3), according to the characteristics of the loose soil body, the soil body finishes more than 85% of the slurry absorption in about eight minutes, the subsequent absorption is slight, and therefore slurry supplement is carried out at the moment.

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