A hierarchical grouting anchor cable and construction method

Abstract

The application discloses a kind of hierarchical grouting anchor cable and construction method, belong to geotechnical engineering technical field.The anchor cable is composed of several grouting units, each grouting unit includes grouting pipe, pressing plate, connecting plate, annular high-pressure plugging air bag, gas pipe, water pressure balance pipe, connecting pipe and one-way valve.The application discloses a kind of construction method of hierarchical grouting anchor cable, by setting grouting unit at different positions of anchor cable, and control the size of each one-way valve opening pressure, divide anchor cable into several grouting areas, using hole top to hole bottom grouting mode, realizes the hierarchical grouting of anchor cable.The application effectively avoids the problems such as slurry stringing, slurry leakage, excess, pressure does not come up, etc., realizes the fixed-point quantitative grouting of rock-soil body, not only improves the grouting quality of anchor cable, but also saves grouting material, and the economic benefit is remarkable.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of geotechnical engineering, and particularly relates to a graded grouting anchor cable and a construction method. BACKGROUND

[0002] A key factor of anchoring engineering quality is grouting quality. From the anchoring accidents in many years, the grouting quality is one of the most core and most common technologies affecting the anchoring quality, and the anchor cable hole grouting and construction technology is a main factor affecting the grouting quality. At present, in the aspect of grouting plug in the hole, a grouting plug is mostly used for grouting. The conventional grouting plug is difficult to achieve the effect in some undesirable working environments, and may cause grouting failure such as grouting leakage and grouting stringing. Therefore, a large amount of research has been carried out for the deficiencies of the anchor cable grouting plug.

[0003] A construction method of an anchor cable structure using an expansive soil anchor cable grouting plug is disclosed in a Chinese patent with the authorized announcement number CN104164874B. The expansive soil anchor cable grouting plug includes a centering support, a steel strand, a high-pressure grouting pipe and expansive soil. The expansive soil is wrapped between each of the steel strands after being packaged by a flexible material, the high-pressure grouting pipe passes through the expansive soil, and the centering support is arranged at both ends of the expansive soil anchor cable grouting plug. When used, the expansive soil with strong expansion characteristics is used as a raw material, and a layer of geotextile or non-woven fabric is wrapped around the periphery of the raw material. After the expansive soil anchor cable grouting plug expands when meeting water, strong axial force is generated between the expansive soil anchor cable grouting plug and the hole wall, so that the contact between the expansive soil anchor cable grouting plug and the hole wall is more closely. However, the grouting structure has the following deficiencies: firstly, the expansive soil is prepared and filled in flexible bags after steps such as rolling, drying and screening, and then filled into the flexible bags according to the proportion; secondly, the flexible bags containing the expansive soil need to be manually wrapped between each of the steel strands, so that the anchor cable production efficiency is low, and the binding method and installation position have uncontrollable human factors, so it is difficult to achieve uniform standardization in installation and production; in addition, the flexible material containing the expansive soil wrapped on the steel strand is easily damaged by friction with the rough hole wall during installation of the anchor cable, and the expansive soil leaks to affect the grouting effect.

[0004] A kind of suitable for rock slope support anchor cable grouting stop grouting device and its using method are disclosed in Chinese invention patent with publication number CN108316318A.The device is provided with soft rubber capsule in the middle of steel strand, and the soft rubber capsule is grouted during construction, when grouting net pressure exceeds 0.2MPa, the soft rubber capsule has been in close contact with anchor hole wall, and stop grouting is realized.However, the stop grouting device has the following problems: firstly, the soft rubber capsule is arranged in the middle of steel strand, and it is difficult to fix, and it is easy to move;Secondly, when grouting the soft rubber capsule, the expansion direction of the soft rubber capsule is difficult to fix, and there is a possibility of axial expansion to the anchor hole, which makes it difficult to be in close contact with the hole wall;In addition, there may be gaps between the expanded soft rubber capsule and the second grouting pipe, and it is difficult to achieve sealing.

[0005] A kind of anchor cable stop grouting plug is disclosed in Chinese utility model patent with authorization announcement number CN202039360U.The anchor cable stop grouting plug is sandwiched with silica gel plate in two high-hardness PVC plates, and the two PVC plates and silica gel plate are fixed to form disc-shaped plug body by screw, and the disc-shaped plug body is symmetrically provided with circular reserved holes for grouting pipe, exhaust pipe and steel strand, and the disc-shaped plug body is arranged on anchor cable and fixed, and there are PVC plate anchor cable steel strand reserved hole, PVC plate grouting pipe reserved hole and PVC plate exhaust pipe reserved hole on PVC plate, and there are silica gel plate anchor cable steel strand reserved hole, silica gel plate grouting pipe reserved hole and silica gel plate exhaust pipe reserved hole on silica gel plate.When used, the disc-shaped plug body is sent into hole with anchor cable, and the silica gel plate of PVC plate is turned outwards and pasted on the hole wall to realize stop grouting function.However, the stop grouting anchor cable has the following disadvantages: in actual working condition, the hole wall of anchor hole is not smooth, but rough and uneven, and since the outer diameter of silica gel plate is 20-30mm larger than the diameter of anchor hole to ensure the sealing effect of stop grouting plug, the silica gel plate is rubbed with rough hole wall during installation of anchor cable, which easily causes the stop grouting plug to be stuck by residual rock in hole, and causes difficulty in installation of anchor cable, and in serious case, the stop grouting plug is displaced to make the grouting length unable to meet the predetermined requirement, and even the silica gel plate is damaged to lose stop grouting function.

[0006] In addition, most anchor cable grouting construction processes are in the form of one-time hole bottom back grouting, and if loose, broken and deep anchor hole bottom structure surface is encountered, it will cause the grouting pressure to be unable to rise, and the anchoring section grouting quality is difficult to guarantee. SUMMARY

[0007] The purpose of the present application is to overcome the shortcomings of the prior art, from the aspects of grouting and stop grouting device and construction method, a kind of graded grouting anchor cable and construction method are provided, which can solve the problems of poor sealing performance of grouting and stop grouting device, grouting leakage, grouting mixing and complicated construction process in the implementation of current slope prestressed anchor cable, and significantly improve the grouting effect, so as to achieve the real reinforcement effect of prestressed anchor cable on rock mass.

[0008] To achieve the above object, the present application adopts the following technical solutions:

[0009] 1. A hierarchical grouting anchor cable, characterized in that it comprises an anchor cable main body and an auxiliary device, the anchor cable main body comprises m parallel steel wire bundles, a guide cap, n gas delivery tubes, n water pressure balance tubes and n grouting unit groups of the same structure, wherein n is the number of hierarchical grouting, n≥2;

[0010] Any one of the n grouting units is denoted as grouting unit j, j=1, 2, …, n, in the grouting unit j, from top to bottom, it comprises a pressing plate, an annular high-pressure sealing air bag, a connecting plate, a connecting tube, a one-way valve and a grouting tube; the grouting tube is a hollow circular tube, the tail of which is provided with external threads, and the part below the L1 distance from the upper end surface of the external threads is denoted as a grout overflow area, a plurality of grout overflow holes are opened on the wall of the grout overflow area; the connecting tube is a hollow circular tube with external threads at the top, the pressing plate is a circular plate, and a grouting tube hole A, m steel wire bundle holes A, n gas delivery tube holes and n water pressure balance tube holes A are opened on the circular plate; the connecting plate is a circular plate, and a grouting tube hole B corresponding to the grouting tube hole A, m steel wire bundle holes B corresponding to the steel wire bundle holes A, n gas delivery tube holes B corresponding to the gas delivery tube holes A and n water pressure balance tube holes B corresponding to the water pressure balance tube holes A are opened on the circular plate; the grouting tube hole B is an internal threaded hole; the annular high-pressure sealing air bag is kept concentric with the connecting plate, is placed between the pressing plate and the connecting plate, and is bonded with the connecting plate; the top of the connecting tube is screwed with the grouting tube hole B through the external threads from below the connecting plate, one end of the one-way valve is communicated with the tail end of the connecting tube through a pipe joint, the other end is communicated with the top of the grouting tube through a joint, and the tail of the grouting tube passes through the grouting tube hole A of the grouting unit j+1 below it, then is screwed with the grouting tube hole B in the grouting unit j+1 through external threads, so as to realize the communication of the grouting tube in the grouting unit j with the connecting tube in the grouting unit j+1;

[0011] The assembly of the n grouting units j, n gas delivery tubes and n water pressure balance tubes is as follows: one end of one gas delivery tube is communicated with a multi-way ball valve in the auxiliary device, the other end passes through the gas delivery tube hole A and the gas delivery tube hole B of the grouting unit above the grouting unit j in sequence, the gas delivery tube hole A in the grouting unit j and the inflation port of the annular high-pressure sealing air bag in the grouting unit j are communicated; one end of one water pressure balance tube is communicated with the atmosphere, the other end passes through the water pressure balance tube hole A and the water pressure balance tube hole B of the grouting unit above the grouting unit j and the grouting unit j, and is cut off at a distance L2 below the water pressure balance tube hole B of the grouting unit j;

[0012] The m steel wire bundles pass through the steel wire bundle holes A and steel wire bundle holes B in the n grouting units in sequence from above the grouting unit 1 and are collected in the guide cap;

[0013] In operation, the anchor cable body is installed in the anchor cable hole.

[0014] Preferably, tool anchor clamps are embedded in the steel wire bundle holes A, steel wire bundle holes B, water pressure balance pipe holes A and water pressure balance pipe holes B, and are sealed by strong glue; the gas pipe holes A and gas pipe holes B that are not passed through by the gas pipes are plugged by plugs, and the water pressure balance pipe holes A and water pressure balance pipe holes B that are not passed through by the water pressure balance pipes are plugged by plugs.

[0015] Preferably, the positions of the m steel wire bundles, grouting pipes, gas pipes and water pressure balance pipes all fall within the inner ring of the annular high-pressure plugging air bag.

[0016] Preferably, L1=15cm-30cm, and L2=5cm-10cm.

[0017] Preferably, a tight ring and an expansion ring are arranged between the one-way valve and the grouting pipe of each grouting unit.

[0018] Preferably, the length A1 of the connecting pipe is 1 / 20-1 / 40 of the length A2 of the grouting pipe.

[0019] The diameter of the pressing plate is D1, the diameter of the connecting plate is D2, and the diameter of the anchor cable hole is D, which satisfy D2≤D1<D, and 2cm≤(D-D1)≤3cm; the length h of the anchor cable in the anchor cable hole and the depth H of the anchor cable hole satisfy the relationship: H-h≤50cm.

[0020] Preferably, the auxiliary device comprises a grouting device, a pressure gauge, a stirrer, an air compressor and a multi-way ball valve, wherein the air compressor is communicated with the n gas pipes in the anchor cable body through the multi-way ball valve, and the stirrer is communicated with the grouting pipes in the anchor cable body through the pressure gauge and the grouting device in sequence.

[0021] The application further provides a construction method of the staged grouting anchor cable, which comprises the following steps:

[0022] Step 1, setting of grouting area and grouting parameters

[0023] From the top end of the anchor cable hole, the grouting area is divided into n grouting areas, and any one of the grouting areas is recorded as grouting area j, wherein grouting area 1 is recorded as a free section, and the remaining n-1 grouting areas are recorded as anchoring sections, and the demarcation point of the grouting area j and the grouting area j+1 is the air bag of the grouting unit j+1.

[0024] The grouting parameters include the starting pressure P.j of the single-way valve of the grouting unit j and the grouting pressure p j ;

[0025] Step 2, anchor cable assembly and processing

[0026] Rust removal treatment is performed on the m steel wire strands;

[0027] A hollow sleeve is sleeved on the outside of the m steel wire strands at the position of the grouting unit 1, and then n grouting units are sequentially installed on the steel wire strands, and finally the steel wire strands are collected in the guide cap;

[0028] The air in the annular high-pressure sealing air bag of the n grouting units is extracted by an air compressor, and the one-way valves of the n grouting units are respectively adjusted to the starting pressure P j ;

[0029] Step 3, push the anchor cable

[0030] The assembled anchor cable is pushed into the anchor cable hole;

[0031] Step 4, free section grouting

[0032] Air is filled into the annular high-pressure sealing air bag of the grouting unit 1 and the grouting unit 2 through the air compressor, the multi-way ball valve and the gas conveying pipe, so that it is tightly fitted with the hole wall of the anchor cable hole;

[0033] The stirrer and the grouting device are connected, and the stirred cement slurry is injected into the grouting pipe of the grouting unit 1 through the grouting device under the grouting pressure p1, and when the thick slurry flows out from the water pressure balance pipe, the grouting is stopped;

[0034] Step 5, anchor section grouting

[0035] Step 5.1, before the thick slurry in step 4 is initially cured, the grouting of the grouting area 2 is performed, specifically as follows:

[0036] Air is filled into the annular high-pressure sealing air bag of the grouting unit 3 through the air compressor, the multi-way ball valve and the gas conveying pipe, so that it is tightly fitted with the hole wall of the anchor cable hole;

[0037] The stirrer and the grouting device are connected, and the stirred cement slurry is injected into the grouting pipe of the grouting unit 2 through the grouting device under the grouting pressure p2, and when the thick slurry flows out from the water pressure balance pipe, the grouting is stopped;

[0038] Step 5.2, according to the method of step 5.1, the grouting of the grouting areas 3-n is sequentially performed before the thick slurry after the grouting of the last grouting area is initially cured;

[0039] Step 6, anchor cable tensioning

[0040] After the n water pressure balance pipes are out of the concentrated slurry and are stable, the reinforced concrete pier, anchor pad and anchor plate are sequentially installed on the anchor cable, the anchor cable is tensioned, and the anchor head outside the anchor cable is locked.

[0041] Preferably, the starting pressure P j and the grouting pressure p j are set as follows:

[0042] Grouting area 1: 0 = P1 < p1 + G1 sin alpha < P2;

[0043] Grouting area 2: P2 < p2 + (G1 + G2) sin alpha < P3;

[0044] ...

[0045] Grouting area n-1: P n-1 < p n-1 + (G1 + G2 +... + G n-1 ) sin alpha < P n ;

[0046] Grouting area n:

[0047] Wherein, G j is the weight of the slurry in the grouting pipe in the grouting unit j when the slurry is full, and alpha is the angle between the anchor cable hole center line and the horizontal plane.

[0048] The beneficial effects of the present application can be summarized as follows:

[0049] (1) The graded grouting anchor of the present application has superior sealing performance, overcomes the poor sealing effect of the existing grout stopper, and effectively avoids the situations of slurry leakage, slurry leakage, and insufficient pressure. The grouting unit composed of a grouting pipe, a pressing plate, a connecting plate, an annular high-pressure sealing air bag, a gas conveying pipe, a water pressure balance pipe, a tool anchor clamp, a connecting pipe and a one-way valve realizes seamless splicing of the grouting pipe and the connecting pipe by setting threaded holes on the connecting plate, realizes fastening and sealing of the steel wire bundle and the water pressure balance pipe by setting the tool anchor clamp on the pressing plate and the connecting plate and adding strong glue, and the combination of the pressing plate and the connecting plate limits the axial expansion of the annular high-pressure sealing air bag, so that the annular high-pressure sealing air bag is in close contact with the hole wall.

[0050] (2) The present application changes the traditional hole bottom return slurry method and adopts the hole top to hole bottom graded grouting construction method. By setting grouting units at different positions of the anchor cable, the opening pressure of each one-way valve is controlled, the anchor cable is divided into several graded grouting areas, the rock-soil body at each position in the anchor cable hole is grouted in a fixed and quantitative manner, the situations of excessive slurry and insufficient grouting pressure are avoided, the grouting quality of the anchoring section is significantly improved, and the grouting material is saved.

[0051] (3) The graded grouting anchor cable structure of the present invention is simple, easy to install, reasonable and feasible in construction method, convenient to operate, and has significant economic benefits. It can be used for the support of various slopes, foundation pits and underground caverns. Attached Figure Description

[0052] Figure 1 This is a schematic diagram of the overall structure of the graded grouting anchor cable of the present invention;

[0053] Figure 2 This is a schematic diagram of the pressure plate structure in an embodiment of the present invention;

[0054] Figure 3 This is a schematic diagram of the connecting plate in an embodiment of the present invention;

[0055] Figure 4 This is a schematic diagram of the grouting pipe structure in an embodiment of the present invention;

[0056] Figure 5 This is a schematic diagram of the connecting pipe structure in an embodiment of the present invention;

[0057] Figure 6 This is a schematic diagram of a construction method for graded grouting anchor cables in an embodiment of the present invention.

[0058] In the diagram: 1. Steel wire bundle; 2. Grouting pipe; 3. Overflow hole; 4. Pressure plate; 5. Connecting plate; 6. Annular high-pressure sealing airbag; 7. Air supply pipe; 8. Water pressure balance pipe; 9. Tool anchor clamp; 10. Connecting pipe; 11. One-way valve; 12. Joint; 13. Guide cap; 14. Steel wire bundle hole A; 15. Grouting pipe hole A; 16. Air supply pipe hole A; 17. Water pressure balance pipe hole A; 18. Steel wire bundle hole B; 19. Grouting pipe hole B; 20. Water pressure balance pipe hole B; 21. Hoop ring; 22. Expansion ring; 23. Anchor cable hole; 24. Reinforced concrete pier; 25. Anchor plate; 26. Anchor plate; 27. Grouting device; 28. Pressure gauge; 29. ​​Agitator; 32. Air compressor; 33. Multi-way ball valve; 34. Hollow sleeve; 35. Air supply pipe hole B. Detailed Implementation

[0059] The following is combined Figures 1-6 The specific embodiments of the present invention will be further described below.

[0060] Figure 1 This is a schematic diagram of the overall structure of the graded grouting anchor cable of the present invention. Figure 2 This is a schematic diagram of the pressure plate structure in an embodiment of the present invention. Figure 3 This is a schematic diagram of the connecting plate in an embodiment of the present invention. Figure 4 This is a schematic diagram of the grouting pipe structure in an embodiment of the present invention. Figure 5 This is a schematic diagram of the connecting pipe structure in an embodiment of the present invention. Figures 1-5As can be seen, a graded grouting anchor cable includes an anchor cable body and auxiliary devices. The anchor cable body consists of m parallel steel wire bundles 1, guide caps 13, n air supply pipes 7, n water pressure balance pipes 8, and n grouting units with the same structure, where n is the grade number of graded grouting and n≥2.

[0061] Let any one of the n grouting units be denoted as grouting unit j, j = 1, 2, ..., n. In grouting unit j, from top to bottom, it includes pressure plate 4, annular high-pressure sealing airbag 6, connecting plate 5, connecting pipe 10, one-way valve 11 and grouting pipe 2. The grouting pipe 2 is a hollow circular pipe with external threads at its tail. The portion below L1 from the top of the external thread is designated as the overflow zone, and multiple overflow holes 3 are formed on the pipe wall of this overflow zone. The connecting pipe 10 is a hollow circular pipe with external threads at the top. The pressure plate 4 is a circular flat plate with one grouting pipe hole A15, m wire bundle holes A14, n air supply pipe holes 16, and n water pressure balance pipe holes A17. The connecting plate 5 is a circular flat plate with one grouting pipe hole B19 corresponding to the grouting pipe hole A15, m wire bundle holes B18 corresponding to the wire bundle holes A14, n air supply pipe holes B35 corresponding to the air supply pipe holes A16, and n water pressure balance pipe holes A17. Water pressure balance pipe hole B20; grouting pipe hole B19 is an internally threaded hole; the annular high-pressure sealing airbag 6 is concentric with the connecting plate 5, placed between the pressure plate 4 and the connecting plate 5, and bonded to the connecting plate 5; the top of the connecting pipe 20 is screwed to the grouting pipe hole B19 from below the connecting plate 5 through an external thread; one end of the one-way valve 11 is connected to the tail end of the connecting pipe 5 through a pipe splice 12, and the other end is connected to the top of the grouting pipe 2 through a splice 12; the tail of the grouting pipe 2 passes through the grouting pipe hole A15 of the grouting unit j+1 below it, and is screwed to the grouting pipe hole B19 in the grouting unit j+1 through an external thread, so as to realize the communication between the grouting pipe 2 in the grouting unit j and the connecting pipe 20 in the grouting unit j+1.

[0062] The assembly of n grouting units j with n air supply pipes 7 and n water pressure balance pipes 8 is as follows: one end of an air supply pipe 7 is connected to the multi-way ball valve 33 in the auxiliary device, and the other end passes through the air supply pipe hole A16 and air supply pipe hole B35 in the grouting unit above the grouting unit j in sequence. The air supply pipe hole A16 in the grouting unit j is connected to the inflation port of the annular high-pressure sealing airbag 6 in the grouting unit j; one end of a water pressure balance pipe 8 is open to the atmosphere, and the other end passes through the water pressure balance pipe hole A17 and water pressure balance pipe hole B20 above the grouting unit j, and ends at a distance L2 below the water pressure balance pipe hole B20 of the grouting unit j.

[0063] The m steel wire bundles 1 start from above the grouting unit 1, pass sequentially through the steel wire bundle holes A14 and B18 in the n grouting units, and are then collected in the guide cap 13.

[0064] During operation, the anchor cable body is installed in the anchor cable hole 23.

[0065] In this embodiment, tool anchor clips 9 are embedded in the wire bundle holes A14, B18, A17, and B20, and are sealed with strong adhesive.

[0066] In this embodiment, gas pipe holes A16 and B35, through which the gas pipe 7 does not pass, were sealed with plugs, and water pressure balance pipe holes A17 and B20, through which the water pressure balance pipe 8 does not pass, were sealed with plugs. Figure 2 and Figure 3 These are the pressure plate and connecting plate of the second grouting unit, respectively. The diagram shows the sealing situation.

[0067] In this embodiment, the positions of the m steel wire bundles 1, grouting pipe 2, air supply pipe 7, and water pressure balance pipe 8 all fall within the inner ring of the annular high-pressure sealing airbag 6.

[0068] In this embodiment, L1 = 15cm - 30cm and L2 = 5cm - 10cm.

[0069] In this embodiment, a clamping ring 21 and an expansion ring 22 are installed between the one-way valve 11 and the grouting pipe 2 of each grouting unit.

[0070] In this embodiment, the length A1 of the connecting pipe 10 is 1 / 20 to 1 / 40 of the length A2 of the grouting pipe 2.

[0071] In this embodiment, the diameter of the pressure plate 4 is denoted as D1, the diameter of the connecting plate 5 as D2, and the diameter of the anchor cable hole 23 as D. The three satisfy D2≤D1<D, and 2cm≤(D-D1)≤3cm. The anchor cable length h in the anchor cable hole and the anchor cable hole depth H satisfy the relationship: Hh≤50cm.

[0072] In this embodiment, the auxiliary device includes a grout injector 27, a pressure gauge 28, a stirrer 29, an air compressor 32, and a multi-way ball valve 33. The air compressor 32 is connected to n air supply pipes 7 in the anchor cable body through the multi-way ball valve 33, and the stirrer 29 is connected to the grouting pipe 2 in the anchor cable body through the pressure gauge 28 and the grout injector 27.

[0073] Figure 6 This is a schematic diagram of a construction method for a graded grouting anchor cable according to an embodiment of the present invention. As shown in the diagram, the construction method for a graded grouting anchor cable provided by the present invention includes the following steps:

[0074] Step 1: Setting the grouting zone and grouting parameters

[0075] Starting from the top of the anchor cable hole 23, the grouting area is divided into n grouting zones, and any one of the grouting zones is denoted as grouting zone j. Among them, grouting zone 1 is denoted as the free section, and the remaining n-1 grouting zones are denoted as the anchoring section. The boundary point between grouting zone j and grouting zone j+1 is the air bladder of grouting unit j+1.

[0076] The grouting parameters include the starting pressure P of the one-way valve 11 of the grouting unit j. j and grouting pressure p j ;

[0077] Step 2, Anchor Cable Assembly and Processing

[0078] Rust removal treatment is performed on the m steel wire bundles 1;

[0079] A hollow sleeve 34 is fitted over the outside of the m steel wire bundles 1 at the grouting unit 1 position. Then, n grouting units are installed on the steel wire bundles 1 in sequence. Finally, the steel wire bundles 1 are put into the guide cap 13.

[0080] The air in the annular high-pressure sealing airbags 6 of the n grouting units is evacuated by the air compressor 32, and the one-way valves of the n grouting units are adjusted to the starting pressure Pj respectively.

[0081] Step 3, push the anchor cable

[0082] Push the assembled anchor cable into the anchor cable hole 23;

[0083] Step 4, Grouting of the free section

[0084] Air is injected into the annular high-pressure sealing airbags 6 of grouting unit 1 and grouting unit 2 through air compressor 32, multi-way ball valve 33, and air supply pipe 7, so that they fit tightly against the hole wall of anchor cable hole 23.

[0085] Connect the mixer 29 and the grout injector 27. Under the grouting pressure p1, inject the mixed cement slurry into the grouting pipe 2 of the grouting unit 1 through the grout injector 29. Stop grouting when thick slurry gushes out from the water pressure balance pipe 8.

[0086] Step 5, Grouting of the anchorage section

[0087] Step 5.1: Before the initial setting of the thick slurry described in step 4, grouting is performed in grouting zone 2, as follows:

[0088] Air is injected into the annular high-pressure sealing airbag 6 of the grouting unit 3 through the air compressor 32, multi-way ball valve 33, and air supply pipe 7, so that it fits tightly against the hole wall of the anchor cable hole 23.

[0089] Connect the mixer 29 and the grout injector 27. Under the grouting pressure p2, inject the mixed cement slurry into the grouting pipe 2 of the grouting unit 2 through the grout injector 29. Stop grouting when thick slurry gushes out of the water pressure balance pipe 8.

[0090] Step 5.2: Following the method in Step 5.1, before the thick grout from the previous grouting zone initially sets, proceed with grouting in grouting zones 3 through grouting zone n in sequence.

[0091] Step 6, Anchor cable tensioning

[0092] After the thick slurry flowing from the n water pressure balance pipes 8 has solidified and stabilized, reinforced concrete piers 24, anchor plates 25 and anchor plates 26 are installed on the anchor cable in sequence, the anchor cable is tensioned, and the anchor head outside the anchor cable is locked.

[0093] In this embodiment, the starting pressure P j and the grouting pressure p j The settings are as follows:

[0094] Grouting zone 1: 0 = P1 < p1 + G1sinα < P2;

[0095] Grouting zone 2: P2 < p2 + G1 + G2sinα < P3;

[0096] ...

[0097] Grouting zone n-1: P n-1 <p n-1 +G1+G2+...+G n-1 sinα<P n ;

[0098] Grouting zone n:

[0099] Among them, G j α is the weight of the grout in the grouting pipe 2 of grouting unit j when it is full, and α is the angle between the anchor cable and the horizontal plane.

[0100] The specific parameters in this embodiment are as follows:

[0101] In this embodiment, the length of the free section and the length of the anchoring section are set according to the geological conditions of the rock and soil mass. Based on this, the number of grouting stages n, the length of the anchor cable in the anchor cable hole h, and the depth of the anchor cable hole H are given. Specifically, n=3, the anchor cable length h is 20m, the anchor cable hole depth H is 20.5m, the length of the free section of the anchor cable is 13m, and the length of the anchoring section is 7m. It includes two grouting zones, where grouting zone 2 is 3m long and grouting zone 3 is 4m long. The rock and soil structural surface is located in the middle of grouting zone 2, and the consistency of the cement grout injected in grouting zone 2 is greater than that in other grouting zones.

[0102] In this embodiment, P1 is 0 MPa, P2 is 1.0 MPa, P3 is 2.0 MPa, D is 15 cm, D1 is 13 cm, D2 is 12 cm, and m = 4.

[0103] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A graded grouting anchor cable, characterized in that, It includes the anchor cable body and auxiliary devices. The anchor cable body consists of m parallel steel wire bundles (1), guide caps (13), n air supply pipes (7), n water pressure balance pipes (8) and n grouting units with the same structure, where n is the number of stages of graded grouting and n≥2. Let any one of the n grouting units be denoted as grouting unit j, j = 1, 2, ..., n. In grouting unit j, from top to bottom, it includes a pressure plate (4), an annular high-pressure sealing airbag (6), a connecting plate (5), a connecting pipe (10), a one-way valve (11), and a grouting pipe (2). The grouting pipe (2) is a hollow round pipe with an external thread at its tail. The portion below the distance L1 from the upper end of the external thread is called the overflow zone. Multiple overflow holes are opened on the pipe wall of the overflow zone. 3); The connecting pipe (10) is a hollow round pipe with external threads on the top; the pressure plate (4) is a circular plate with one grouting pipe hole A (15), m wire bundle holes A (14), n air supply pipe holes (16) and n water pressure balance pipe holes A (17) on the circular plate; The connecting plate (5) is a circular plate with one grouting pipe hole B (19) corresponding to the grouting pipe hole A (15) and m wire bundle holes B (14) corresponding to the wire bundle holes A (14) on the circular plate. 8) n gas transmission pipe holes B (35) corresponding to gas transmission pipe hole A (16), and n water pressure balance pipe holes B (20) corresponding to water pressure balance pipe hole A (17); the grouting pipe hole B (19) is an internally threaded hole; the annular high-pressure sealing airbag (6) is concentric with the connecting plate (5), placed between the pressure plate (4) and the connecting plate (5), and bonded to the connecting plate (5); the top of the connecting pipe (10) connects to the grouting pipe hole B (19) from below the connecting plate (5) through an external thread. The one-way valve (11) is connected to the tail end of the connecting pipe (10) through a pipe splice (12) and the other end is connected to the top of the grouting pipe (2) through a splice (12). The tail of the grouting pipe (2) passes through the grouting pipe hole A (15) of the grouting unit j+1 below it and is then connected to the grouting pipe hole B (19) in the grouting unit j+1 through an external thread, so as to realize the connection between the grouting pipe (2) in the grouting unit j and the connecting pipe (10) in the grouting unit j+1. The assembly of n grouting units j with n air supply pipes (7) and n water pressure balance pipes (8) is as follows: one end of an air supply pipe (7) is connected to the multi-way ball valve (33) in the auxiliary device, and the other end passes through the air supply pipe hole A (16) and air supply pipe hole B (35) in the grouting unit above the grouting unit j in sequence. The air supply pipe hole A (16) in the grouting unit j is connected to the air inlet of the annular high-pressure sealing airbag (6) in the grouting unit j. One end of a water pressure balance pipe (8) is open to the atmosphere, and the other end passes through the water pressure balance pipe hole A (17) and water pressure balance pipe hole B (20) above the grouting unit j and the grouting unit j, and ends at a distance L2 below the water pressure balance pipe hole B (20) of the grouting unit j. The m steel wire bundles (1) start from above the grouting unit 1 and pass through the steel wire bundle holes A (14) and B (18) in the n grouting units in sequence, and are then stored in the guide cap (13). Tool anchor clips (9) are embedded in wire bundle holes A (14), wire bundle holes B (18), water pressure balance pipe holes A (17) and B (20), and are sealed with strong adhesive; gas pipe holes A (16) and B (35) without gas pipe (7) passing through are sealed with plugs; water pressure balance pipe holes A (17) and B (20) without water pressure balance pipe (8) passing through are sealed with plugs. During operation, the anchor cable body is installed in the anchor cable hole (23).

2. The graded grouting anchor cable according to claim 1, characterized in that, The positions of the m steel wire bundles (1), grouting pipe (2), gas transmission pipe (7), and water pressure balance pipe (8) all fall within the inner ring of the annular high-pressure sealing airbag (6).

3. The graded grouting anchor cable according to claim 1, characterized in that, L1 = 15cm - 30cm, and L2 = 5cm - 10cm.

4. The graded grouting anchor cable according to claim 1, characterized in that, A clamping ring (21) and an expansion ring (22) are installed between the one-way valve (11) and the grouting pipe (2) of each grouting unit.

5. A graded grouting anchor cable according to claim 1, characterized in that, The length A1 of the connecting pipe (10) is 1 / 20 to 1 / 40 of the length A2 of the grouting pipe (2). Let the diameter of the pressure plate (4) be D1, the diameter of the connecting plate (5) be D2, and the diameter of the anchor cable hole (23) be D. The three satisfy D2≤D1<D and 2cm≤(D-D1)≤3cm. The anchor cable length h in the anchor cable hole (23) and the depth H of the anchor cable hole (23) satisfy the relationship: H–h≤50cm.

6. A graded grouting anchor cable according to claim 1, characterized in that, The auxiliary device includes a grout injector (27), a pressure gauge (28), a stirrer (29), an air compressor (32), and a multi-way ball valve (33). The air compressor (32) is connected to n air supply pipes (7) in the anchor cable body through the multi-way ball valve (33). The stirrer (29) is connected to the grouting pipe (2) in the anchor cable body through the pressure gauge (28) and the grout injector (27) in sequence.

7. A construction method for a graded grouting anchor cable, employing a graded grouting anchor cable as described in any one of claims 1-6, characterized in that, The construction method includes the following steps: Step 1: Setting the grouting zone and grouting parameters Starting from the top of the anchor cable hole (23), the grouting area is divided into n grouting areas, and any one of the grouting areas is denoted as grouting area j. Among them, grouting area 1 is denoted as the free section, and the remaining n-1 grouting areas are denoted as the anchoring section. The boundary point between grouting area j and grouting area j+1 is the air bladder of grouting unit j+1. The grouting parameters include the starting pressure P of the one-way valve (11) of grouting unit j. j and grouting pressure p j ; The starting pressure P j and the grouting pressure p j The settings are as follows: Grouting Zone 1: 0 = P1 <p1+G1sinα<P2; Grouting Zone 2: P2 <p2+(G1+G2)sinα<P3; …… Grouting zone n-1: P n-1 <p n-1 +(G1+G2+…+G n-1 sinα <P n ; Grouting zone n: Among them, G j α is the weight of the grout in the grouting pipe (2) in grouting unit j when it is full, and α is the angle between the center line of the anchor hole and the horizontal plane. Step 2, Anchor Cable Assembly and Processing Rust removal treatment was performed on m steel wire bundles (1); A hollow sleeve (34) is fitted over the m wire bundles (1) at the grouting unit 1. Then, n grouting units are installed on the wire bundles (1) in sequence. Finally, the wire bundles (1) are put into the guide cap (13). The air in the annular high-pressure sealing airbags (6) of the n grouting units is evacuated by the air compressor (32), and the one-way valves of the n grouting units are adjusted to the starting pressure P respectively. j ; Step 3, push the anchor cable The assembled anchor cable is pushed into the anchor cable hole (23); Step 4, Grouting of the free section Air is injected into the annular high-pressure sealing airbags (6) of grouting unit 1 and grouting unit 2 through air compressor (32), multi-way ball valve (33) and air supply pipe (7) so that they fit tightly against the hole wall of anchor cable hole (23); Connect the mixer (29) and the grouter (27). Under the grouting pressure p1, inject the well-mixed cement slurry into the grouting pipe (2) of the grouting unit 1 through the grouter (29). Stop grouting when thick slurry gushes out from the water pressure balance pipe (8). Step 5, Grouting of the anchorage section Step 5.1: Before the initial setting of the thick slurry described in step 4, grouting is performed in grouting zone 2, as follows: Air is injected into the annular high-pressure sealing airbag (6) of the grouting unit 3 through the air compressor (32), multi-way ball valve (33), and air supply pipe (7) so that it fits tightly against the hole wall of the anchor cable hole (23); Connect the mixer (29) and the grouter (27). Under the grouting pressure p2, inject the well-mixed cement slurry into the grouting pipe (2) of the grouting unit 2 through the grouter (29). Stop grouting when thick slurry gushes out from the water pressure balance pipe (8). Step 5.2: Following the method in Step 5.1, before the thick grout from the previous grouting zone initially sets, proceed with grouting in grouting zones 3 through grouting zone n in sequence. Step 6, Anchor cable tensioning After the thick slurry flowing from the n water pressure balance pipes (8) has solidified and stabilized, reinforced concrete piers (24), anchor plates (25) and anchor plates (26) are installed on the anchor cable in sequence, the anchor cable is tensioned, and the anchor head outside the anchor cable is locked.

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