Water-slurry replacement grouting method for broken water-rich roof and bag anchor cable

Abstract

The invention discloses a water-slurry replacement grouting method for a broken water-rich roof and a bag anchor cable. The water-slurry replacement grouting method comprises the steps that firstly, water in water guiding fractures between loose rock blocks in a roadway broken roof rock stratum is drained in advance; when the roof water is drained or the water amount is obviously reduced, the bag anchor cable is used for anchoring and applying pre-tightening force to the roof deep broken surrounding rock, meanwhile, the bag is used for conducting water plugging on the roof deep broken surrounding rock, and the purpose of water plugging is to reduce fractures of the deep broken surrounding rock through the extrusion effect; a deep water plugging area is formed by the deep broken surrounding rock, and after water plugging is finished, the anchor cable and the bag cooperate to achieve pulling-pressing combined bearing. And finally, low-pressure grouting is carried out in the shallow grouting area, so that the grouting slurry is gradually filled to the deep layer from the outside to the inside. The three measures cooperate to enhance the bearing capacity of the roof, reduce the deformation of the surrounding rock of the roadway, improve the long-term stability, and realize the treatment of the broken water-rich roof from traditional passive support to active regulation.

Description

Technical Field

[0001] The present invention belongs to the field of geotechnical engineering support, and particularly relates to a bladder anchor cable for breaking water-rich roofs and a water-slurry replacement grouting method. Background Art

[0002] During the construction of mine roadways, tunnels and underground projects, the treatment of broken water-rich roofs has always been a key technical problem. Due to the long-term influence of mining or geological structure on the rock strata, the roof rock strata often show characteristics such as fragmentation, looseness, and discontinuous structure, and the fissures are developed, which are likely to form water-conducting channels, resulting in serious water seepage in the roadway. The high water content state not only reduces the mechanical strength of the rock strata, but also may cause disasters such as water inrush, roof fall, and collapse, seriously threatening the safety and stability of the roadway. At present, the treatment methods for broken water-rich roofs mainly include technologies such as high-pressure grouting, anchor cable reinforcement, and drainage. However, these methods still have many limitations in practical applications. (1) In the environment of water-rich rock strata, the slurry of high-pressure grouting (the pressure is usually >5MPa, and can reach 10-20MPa) is easily washed or diluted by fissure water, reducing the bonding strength of the slurry and unable to form a high-strength sealing layer. In addition, the diffusion path of the slurry is difficult to accurately control, and there may be situations of excessive or insufficient grouting in local areas, affecting the grouting reinforcement effect. (2) The anchor cable or bolt reinforcement method mainly relies on mechanical anchoring or chemical anchoring agents, which cannot fundamentally improve the integrity of the broken rock strata. Moreover, in a water-rich environment, the curing speed of the anchoring agent is significantly affected by water, resulting in a decrease in the anchoring force or even anchor pull-out, affecting the overall support effect. (3) Only draining water through drainage holes can reduce the water pressure in the rock strata in the short term, but it cannot fundamentally solve the problems of rock stratum fragmentation and fissure water conduction. Once the drainage measures stop or the external water source is conducted, water inrush accidents are likely to occur; at the same time, during the drainage process, the water flow may intensify the erosion of the rock strata, further expanding the water-conducting fissures and even deteriorating the stability of the surrounding rock.

[0003] To solve the above problems, there is a sandwich arch and construction method suitable for the surrounding rock support of high-stress soft rock tunnels in the prior art (Patent No.: CN201811158669.8). This method divides the tunnel surrounding rock into an outer ring bearing arch, an interlayer bolt reinforcement arch, and an inner ring bearing arch of the surrounding rock from the outside to the inside by means of grouting anchor cables + bolts + concrete lining, and can achieve the long-term stability of the surrounding rock of high-stress soft rock tunnels. However, for broken water-rich rock strata, the bolts and anchor cables are easily soaked in water for a long time, and anchor pull-out is likely to occur, and their anchoring performance cannot be fully exerted. In addition, the grouting slurry is easily washed and diluted by water flow, resulting in uneven slurry diffusion and affecting the grouting effect.

[0004] Chinese Patent Application No. 202410588305.2 discloses a rapid water blocking and drainage device for a water-rich karst tunnel and its usage method. It utilizes a grouting bladder that combines the functions of reinforcement and water prevention and drainage to effectively reinforce the tunnel surrounding rock, while achieving the effects of water blocking and drainage and reducing the harm of tunnel seepage. However, its water blocking and drainage occur simultaneously. That is to say, it uses the grouting bladder to squeeze the fractured zone, and the water in the fractured zone is squeezed out and flows into the drain pipe for drainage through extrusion. However, in a water-rich fractured zone, the water flow is large and the permeability is strong. Relying solely on natural drainage during bladder grouting is difficult to quickly drain a large amount of groundwater. When the water pressure is not released in advance, the high-pressure groundwater directly acts on the surface of the bladder. The grouting bladder is impacted by the dynamic water pressure. If the tensile strength of the bladder material is insufficient, it is prone to tearing or leakage, resulting in the failure of the bladder function. In addition, its drainage flows into the drain pipe for discharge and cannot form channels in the rock mass. In the later stage, when grouting into the rock mass, it is difficult to accurately control the diffusion path of the grout, resulting in uneven grouting. Summary of the Invention

[0005] Aiming at problems such as poor stability of the fractured water-rich roof rock formation, developed water-conducting fissures, difficult to accurately control the diffusion path of traditional grouting slurry, easy dilution or loss of slurry, insufficient anchoring force, and long-term water seepage affecting the safety of the roadway, the present invention provides a water-slurry replacement grouting method for fractured water-rich roof and a bladder cable bolt for this method, thus thoroughly solving problems such as large water spraying and difficult control of the fractured water-rich roof of the roadway.

[0006] The object of the present invention is achieved through the following technical solutions:

[0007] A water-slurry replacement grouting method for fractured water-rich roof, characterized by comprising the following steps:

[0008] Step 1: Pre-drain water

[0009] Construct a number of water drainage holes on the roadway roof to pre-drain the water in the water-conducting fissures between the loose rock blocks in the fractured roof rock formation of the roadway.

[0010] Step 2: Block water and reinforce the deep fractured surrounding rock of the roof

[0011] After the roof water is drained or the water volume significantly decreases, first use a cable bolt with a bladder to anchor and apply a pre-tightening force to the deep fractured surrounding rock of the roof, and then use the bladder to block water for the deep fractured surrounding rock of the roof. The purpose of water blocking is to reduce the fissures of the deep fractured surrounding rock through the squeezing action of the bladder, so that a deep water blocking area is formed in the deep fractured surrounding rock. After water blocking, the cable bolt and the bladder cooperate to achieve a combined tension-compression load-bearing.

[0012] Step 3: Shallow grouting

[0013] Below the deep water blocking area is the shallow grouting area. Low-pressure grouting is carried out in the shallow grouting area, so that the grouting slurry gradually fills the deep layer from the surface to the inside.

[0014] Furthermore, in order to prevent the collapse or blockage of the later drainage holes under the extrusion of the bladder, resulting in the loss of the drainage function of the deep boreholes, the hole depth described in Step 1 should be less than the arrangement depth of the bladder.

[0015] Furthermore: The detailed method of Step 2 is as follows:

[0016] 2.1: After the roof water is drained or the water volume decreases significantly, several cable bolt holes are constructed in the roof of the roadway. The depth of the cable bolt holes penetrates into the stable rock stratum, that is, the depth of the cable bolt holes is greater than the thickness of the broken roof rock stratum;

[0017] 2.2: Send the cable bolt with the bladder, together with the anchoring agent cartridge, to the bottom of the cable bolt hole. After the anchoring agent at the bottom of the hole breaks and solidifies, install the tray and locking device, and apply a certain pre-tightening force to the cable bolt, so that the cable bolt is anchored in the stable rock stratum above the broken roof rock stratum;

[0018] 2.3: Use the grouting pump station to pump the grouting slurry into the bladder. The grouting slurry enters the bladder through the grouting pipe arranged in the center of the cable bolt. Stop grouting when the design pressure is reached or when it suddenly increases by 20% - 30%; during this process, the bladder gradually expands under the action of the grouting slurry pressure and squeezes the loose rock blocks around the hole wall. The loose rock blocks are squeezed against each other under the action of the bladder expansion pressure, and the water-conducting fissures gradually shrink or even completely close. The area of the broken roof rock stratum that is squeezed is divided into the deep water blocking area. The deep water blocking area not only improves the integrity of the broken roof, but also can resist the influence of the aquifer or goaf water accumulation in the stable rock stratum or the overlying rock stratum; in addition, the bladder grouting expands and squeezes the loose rock, causing the remaining water in the water-conducting fissures to diffuse outward. At this time, the drainage holes continuously drain the water entering the lower part of the deep water blocking area and the remaining water in the original water-conducting fissures;

[0019] 2.4: After stopping grouting, maintain the pressure briefly to ensure that the bladder is fully expanded and compacts the surrounding fractured rock mass, and then relieve the pressure after the internal grouting slurry solidifies.

[0020] Furthermore: In Step 2.3, it is also possible to determine whether to stop grouting by monitoring the drainage volume. When the bladder squeezes the loose rock blocks around the hole wall, the drainage volume should first increase and then decrease and approach 0. When the drainage volume approaches 0, stop grouting.

[0021] Furthermore, the detailed method of Step 3 is as follows:

[0022] 3.1: Construct several bolt holes in the shallow grouting area of the roof of the roadway. The maximum hole depth of the bolt holes should be located in the deep water blocking area;

[0023] 3.2: Install several grouting bolts on the roadway roof, and send them together with the anchoring agent cartridges to the bottom of the bolt hole. After the anchoring agent at the bottom of the hole breaks and solidifies, install a grout stopper at the front of the bolt (i.e., the hole mouth end), and then install the tray and tighten the fastening nut. At this time, the fastening nut not only fixes the tray but also applies a certain pre-tightening force to the grouting bolt.

[0024] 3.3: Use a grouting pump station to carry out grouting construction on the grouting bolts. Adopt the method of low-pressure grouting to make the grouting slurry diffuse from the shallow part to the deep part. When the pressure of the grouting pump station increases significantly, it indicates that the shallow grouting area has been fully filled with the grouting slurry. At this time, stop the grouting construction.

[0025] Furthermore, the water drainage holes, cable bolt holes and bolt holes can be arranged staggeredly on the same cross-section, or can be arranged staggeredly within a certain space range to form a regional water-slurry replacement.

[0026] To implement the above method, the present invention provides a bag-type cable bolt for the water-slurry replacement grouting method for a broken water-rich roof. It includes a locking device, a tray and a cable bolt body formed by steel strands. It is characterized in that a grouting bag is sleeved on the free section of the cable bolt body near the bottom of the hole. Both ends of the grouting bag are fixedly connected to the cable bolt body through steel sealing rings, and the outer diameter of the sealing ring is adapted to the inner diameter of the cable bolt hole; the steel strands of the cable bolt body are arranged in a blossoming shape inside the grouting bag, and a grouting pipe passes through the center of the cable bolt body. The slurry outlet of the grouting pipe is located at the blossoming arrangement of the steel strands, which is beneficial to the full diffusion of the grouting slurry in the grouting bag; it is required that the material of the grouting bag should have a rigid supporting force when filled and be in an amorphous state after being emptied.

[0027] Furthermore, the grouting bag is a high-strength and pressure-resistant flexible fabric, with characteristics such as waterproof, corrosion-resistant, anti-friction and high expansibility. For example, high-strength polyester fiber material is selected, which has both a certain rigidity and a certain softness.

[0028] Furthermore, in order to realize the sealed connection between the bag and the steel sealing ring, grooves (the width is slightly smaller than the thickness of the bag) are processed on the end face of the steel sealing ring. The end of the bag is embedded in the groove, and mechanical biting is used to prevent the axial slip of the bag.

[0029] The advantages of the present invention are as follows:

[0030] (1) The water-slurry replacement grouting method of the present invention is carried out in the order of continuous water drainage + deep water blocking + shallow grouting. In the early stage, the hydrostatic pressure in the roof rock formation is released through borehole drainage. In this way, when using the bladder anchor cable to squeeze the broken roof rock formation, the broken roof rock formation is more likely to self-embed and reinforce itself, promoting the gradual closure of fissures and achieving precise control of the deep-shallow partition; at the same time, continuous water drainage forms channels in the shallow part of the roof rock formation, laying a foundation for the subsequent shallow grouting to adopt a low-pressure method. Not only is the slurry diffusion path easy to precisely control and the slurry distribution is uniform, but also the formed channels promote the slurry of "shallow grouting" to fill in a progressive manner from the surface to the inside, avoiding problems such as low grouting efficiency caused by the "water-slurry" competition. The coordinated cooperation of the three measures enhances the bearing capacity of the roof, reduces the deformation of the roadway surrounding rock, improves the long-term stability, and realizes the transformation of the treatment of broken water-rich roofs from traditional passive support to active regulation.

[0031] (2) The bladder anchor cable of the present invention enables the deep loose rock blocks in the broken roof rock formation to be squeezed and self-embedded and reinforced under the action of the bladder expansion pressure. This not only helps to improve the integrity of the rock formation but also cuts off the connection with the external water source, effectively blocking the infiltration of water from the overlying aquifer or the accumulated water in the goaf; in addition, the extrusion force at the grouting bladder improves the stress concentration environment where the anchor cable is only subjected to tensile force, realizes the tension-compression coordination of the anchor cable, and reduces the risk of fracture and failure.

[0032] (3) The present invention combines the bladder with the anchor cable for use, which can, to a certain extent, improve the stress environment where the anchor cable is only subjected to tensile force. When the bladder is grouted and expands, while the bladder provides an extrusion force to the broken surrounding rock, the damaged rock mass also provides a reaction force to the bladder. At this time, a part of the tensile force of the anchor cable at the bladder is converted into the pressure of the bladder on the broken surrounding rock, avoiding the stress concentration of the anchor cable. Finally, the two cooperate to form a tension-compression combined bearing, which can produce multi-dimensional synergistic effects; in addition, the radial extrusion force generated by the bladder expansion cooperates with the longitudinal tensile force of the anchor cable to reconstruct the three-dimensional stress field, and the two form a composite stress field, promoting the stress transfer path to change from chain transfer to grid distribution. The roof rock mass shows better energy dissipation characteristics. Under the synergistic action of the bladder, the mechanical properties of the anchor cable are optimized, making it more adaptable to the deformation of the surrounding rock, reducing damage, and extending the service life.

[0033] (4) The present invention conducts low-pressure grouting construction on the shallow broken roof rock formation through grouting bolts, enabling the slurry to gradually diffuse from the shallow part to the deep part, realizing progressive reinforcement from shallow to deep and from the surface to the inside, avoiding the uncontrollability of slurry diffusion and the risk of secondary damage to the rock mass when using high-pressure grouting in the prior art; at the same time, the "slurry-rock" structure formed by the bonding of the grouting slurry and the loose rock blocks improves the integrity and bearing capacity of the roof rock formation.

[0034] (5) By draining water continuously through the water drainage holes, the present invention can significantly reduce the content of free water in the rock formation, and also reduce the risk of the grouting slurry being diluted or washed away by water during the construction process, avoid the "water-slurry" competition, ensure that the slurry can spread smoothly and solidify, which is beneficial to improving the utilization efficiency of the grouting slurry and enhancing the grouting effect.

[0035] (6) The present invention can effectively avoid waste of grouting materials and save control costs. Traditional grouting in water-rich roof is easily diluted or lost by fissure water, resulting in uneven slurry diffusion and poor consolidation effect, and needs to be repeatedly re-injected, with serious material waste. The present invention adopts pre-drainage to reduce the scouring of the slurry by fissure water and reduce the dilution risk. The bag-type anchor cable is used to squeeze and block water, and the deep fissures are closed by the expanding bag to form a water-blocking area to prevent the slurry from flowing into non-target areas. Low-pressure grouting in the shallow part is adopted to fill the fissures within a controllable range to avoid excessive diffusion of the slurry caused by high-pressure grouting. Through the application of the present invention, the slurry utilization rate can be increased by more than 30%, the number of re-injections is reduced, and the cost of single grouting material can be reduced by 20%-40%, with prominent economic benefits.

[0036] (7) The present invention can significantly reduce the risk of anchoring failure and extend the support life. In water-rich rock formations, traditional anchor cables are prone to failure of the anchoring agent and corrosion of the steel strands due to water seepage, resulting in a decrease in the anchoring force and frequent repairs. The present invention squeezes and grouts the fissured rock mass through the grouting bag, while blocking the external water source, forms a tension-compression combined bearing structure with the anchor cable, forms a rigid support area, and cooperates with shallow grouting, which helps to enhance the overall support strength of the broken water-rich roof. Through the application of the present invention, the roof stability is improved, and the roof fall accidents caused by the corrosion failure of the support structure can be reduced by 80%, with significant safety benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. The following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0038] Figure 1 It is a schematic diagram of a bag-type anchor cable structure for a broken water-rich roof;

[0039] Figure 2 It is a schematic diagram of the grouting process of a bag-type anchor cable for a broken water-rich roof;

[0040] Figure 3 It is a schematic diagram of the grouting bag structure;

[0041] Figure 4 It is a front view of the grouting bag structure;

[0042] Figure 5 It is a side view of the grouting bladder structure;

[0043] Figure 6 It is a schematic diagram of the grouting principle of the grouting bladder;

[0044] Figure 7 It is a schematic diagram of the layout of the water drainage holes for the fractured water-rich roof;

[0045] Figure 8 It is a schematic diagram of the process of draining water from the fractured water-rich roof;

[0046] Figure 9 It is a schematic diagram of the installation of the bladder anchor cable for the fractured water-rich roof;

[0047] Figure 10 It is a schematic diagram of the grouting process of the bladder anchor cable for the fractured water-rich roof;

[0048] Figure 11 It is a schematic diagram of the extrusion water-blocking effect of the bladder anchor cable for the fractured water-rich roof;

[0049] Figure 12 It is a schematic diagram of the distribution of the deep water-blocking area - shallow grouting area of the fractured water-rich roof;

[0050] Figure 13 It is a schematic diagram of the installation of the grouting anchor bolt in the shallow grouting area;

[0051] Figure 14 It is a schematic diagram of the grouting process of the grouting anchor bolt in the shallow grouting area;

[0052] Figure 15 It is a schematic diagram of the implementation effect of the water - slurry replacement grouting method for the fractured water-rich roof.

[0053] Figure 16 It is a schematic diagram of the seal ring structure.

[0054] In the figure: 1 - locking device; 2 - tray; 3 - steel strand bundle; 4 - grouting bladder, 41 - sealing ring, 42 - grouting pipe, 43 - bladder; 5 - anchor cable hole; 6 - fractured roof rock stratum, 61 - loose rock, 62 - water-conducting fissure; 7 - grouting slurry; 8 - stable rock stratum; 9 - coal seam; 10 - floor; 11 - roadway; 12 - drainage ditch; 13 - water drainage hole; 14 - grouting pump station; 15 - deep water-blocking area; 16 - shallow grouting area; 17 - grouting anchor bolt; 18 - slurry diffusion range, 19 - groove. Specific implementation manners

[0055] The following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0056] Combined with Figures 1 - 6 and Figure 16 Describe the detailed structure of the capsule anchor cable for the water-slurry replacement grouting method used to break the water-rich roof in the present invention. As can be seen from Figure 1 it, it generally includes an anchor cable body formed by a multi-strand steel strand bundle 3, a locking device 1, a tray 2, and a grouting capsule 4. The grouting capsule 4 is sleeved and fixed on the periphery of the middle and rear part of the anchor cable body (the middle and rear part refers to the part close to the bottom end of the hole). As can be seen from Figure 3 it, the grouting capsule 4 is composed of a capsule 43, a grouting pipe 42, and two stainless steel sealing rings 41. The left and right ends of the capsule 43 are hermetically connected to the sealing rings 41. The outer diameter of the sealing ring 41 is slightly larger than the outer diameter of the anchor cable body, ensuring that the sealing ring can be tightly squeezed by the hole wall after being fed into the anchor cable hole. The capsule 43 is then sleeved on the periphery of the anchor cable body through the sealing ring 41. The sealing ring 41 is welded to the anchor cable body. The grouting pipe 42 passes through the center of the anchor cable body and extends into the capsule 43. The outlet of the grouting pipe 42 in the capsule 43 serves as the grouting outlet. It can also be seen from the figure that the steel strand bundle 3 is arranged in a blooming shape inside the grouting capsule 4, and the slurry outlet of the grouting pipe 42 is just located at the blooming arrangement of the steel strands, which is beneficial to the full diffusion of the grouting slurry in the grouting capsule 4 (see Figure 6 ).

[0057] An annular groove 19 (with a width slightly smaller than the thickness of the capsule) is machined on the end face of the sealing ring. The end of the capsule 43 is embedded in the annular groove 19 to prevent the axial slip of the capsule 43 through mechanical engagement (see Figure 16 ).

[0058] The capsule material of the present invention is a high-strength and pressure-resistant flexible fabric, which has the characteristics of waterproof, corrosion-resistant, anti-friction, high expansibility, etc. High-strength polyester fiber material is preferably used.

[0059] The following combined with Figures 7 - 15 Describe the steps of the water-slurry replacement grouting method implemented by the present invention using the above capsule anchor cable for the broken water-rich roof.

[0060] Step 1: Pre-drain water (see Figures 7 - 8 )

[0061] Refer to Figure 7 , the roadway 11 is arranged in the coal seam 9, and a drainage ditch 12 is excavated on the floor 10 of the roadway. During implementation, first, a number of water drainage holes 13 are constructed on the roof of the roadway 11. The depth of the water drainage holes 13 should be less than the position where the subsequent grouting capsule 4 will be arranged. The water in the water-conducting fissures 62 between the loose rocks 61 in the broken roof rock formation 6 of the roadway is pre-drained by the water drainage holes 7, and the drained roof water is discharged through the drainage ditch 12.

[0062] Step 2: Plug water and reinforce the deeply broken surrounding rock of the roof (see Figures 9 - 11)

[0063] 2.1: After the water in the roof is drained or the water volume decreases significantly, several cable bolt holes 5 are constructed in the roadway roof. The cable bolt holes 5, the water drainage holes 7 and the subsequent bolt holes are arranged staggeredly. The cable bolt holes 5 penetrate deep into the stable rock formation, that is to say, the depth of the cable bolt holes 5 is greater than the thickness of the broken roof rock formation, so as to play the anchoring role of the cable bolts.

[0064] 2.2: Use the drilling rig system to send the bagged cable bolt of the present invention, together with the anchoring agent cartridge, to the bottom of the cable bolt hole 5. After the anchoring agent at the bottom of the hole breaks and solidifies, install the tray 2 and the locking device 1 at the exposed end of the cable bolt, and apply a certain pre-tightening force to the bagged cable bolt, so that the bagged cable bolt 4 is anchored in the stable rock formation 8 above the broken roof rock formation.

[0065] 2.3: Use the grouting pump station 14 installed in the roadway 11 to pump grouting slurry into the bag 43 of the cable bolt through the grouting pipe 42 in the center of the cable bolt. During the grouting process, the pressure needs to be controlled to make the bag fully expand, but not exceed the pressure resistance limit of the bag. When the pressure gauge of the grouting pump station shows a significant increase in pressure, such as reaching the design pressure or suddenly increasing by 20% - 30%, the grouting should be stopped immediately; or monitor the drainage volume of the water drainage hole. The drainage volume should first increase and then decrease and approach 0. When the drainage volume approaches 0, stop grouting. The mechanism is as follows: The bag gradually expands under the action of the grouting slurry pressure and squeezes the loose rock blocks around the hole wall. The loose rock blocks are squeezed against each other under the action of the bag expansion pressure, and the water-conducting fissures gradually shrink or even completely close, dividing the squeezed area in the broken roof rock formation into a deep water-blocking area. The deep water-blocking area not only improves the integrity of the broken roof, but also can resist the influence of the aquifer or the accumulated water in the goaf in the stable rock formation or the overlying rock formation; at the same time, the bag 43 expands and squeezes the loose rock 61 during grouting, making the remaining water in the water-conducting fissure 62 diffuse outward. At this time, the water drainage hole 13 continuously drains the water entering the lower part of the deep water-blocking area 15 and the remaining water in the original water-conducting fissure 62.

[0066] 2.4: After stopping grouting, keep the pressure for 1 - 3 minutes to ensure that the bag is fully expanded and compacts the surrounding fractured rock mass, and then relieve the pressure after the internal grouting slurry solidifies.

[0067] The third step: Shallow grouting (see Figures 13 - 15 )

[0068] Below the deep water-blocking area 15 is the shallow grouting area 16. Low-pressure grouting is carried out on the shallow grouting area 16, so that the grouting slurry gradually fills the deep layer from the surface to the inside; the detailed method of step three is:

[0069] 3.1: Construct several bolt holes in the shallow grouting area 16 of the roadway roof. The maximum depth of the bolt holes should be located in the deep water-blocking area 15.

[0070] 3.2: Install the grouting bolt 17 in the bolt hole, and send it together with the anchoring agent cartridge to the bottom of the bolt hole. After the anchoring agent at the bottom of the hole breaks and solidifies, install a grout stopper at the front part of the grouting bolt 17 (that is, the exposed end of the bolt), and then install the tray and tighten the nut. At this time, the tightened nut not only fixes the tray but also applies a certain pre-tightening force to the grouting bolt 17.

[0071] 3.3: Use the grouting pump station 14 to carry out grouting construction on the grouting bolt 17. Adopt the low-pressure grouting method to make the grouting slurry diffuse from the shallow part to the deep part. When the pressure of the grouting pump station increases significantly, it indicates that the grouting slurry has fully diffused and filled in the shallow grouting area 16 to form Figure 15 the slurry diffusion range 18 as shown. The pressure of low-pressure grouting < 5 MPa, usually 0.5 - 2 MPa.

[0072] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by those skilled in the art within the essence of the present invention should also fall within the protection scope of the present invention.

Claims

1. A water-slurry displacement grouting method for breaking a water-rich roof, characterized in that: The following steps are involved: Step 1: Drain water in advance Several drainage holes are constructed on the tunnel roof to pre-drain the water in the water-conducting fissures between the loose rock blocks in the broken roof rock layer of the tunnel; Step 2: Water blocking and reinforcement of deep broken surrounding rock in the roof When the roof water is drained or the water volume is significantly reduced, first use the anchor cable with the bag to anchor the deep broken surrounding rock of the roof to apply pre-tightening force, and then use the bag to block the water in the deep broken surrounding rock of the roof. The purpose of blocking water is to reduce the cracks in the deep broken surrounding rock through the squeezing effect of the bag, so that the deep broken surrounding rock forms a deep water blocking area. After the water blocking is completed, the anchor cable and the bag cooperate to achieve tension-compression combined bearing; Step 3: Shallow Grouting Below the deep water blocking area is the shallow grouting area, and low-pressure grouting is implemented in the shallow grouting area to allow the grouting slurry to gradually fill into the deep layer from the surface to the inside.

2. The water-slurry displacement grouting method for breaking a water-rich roof according to claim 1, characterized in that: The hole depth described in step 1 should be less than the placement depth of the bladder.

3. The water-slurry replacement grouting method for breaking a water-rich roof according to claim 1, characterized in that: The detailed method of step 2 is: 2.1: When the roof water is drained or the water volume is significantly reduced, several anchor holes are constructed on the tunnel roof. The anchor hole depth goes deep into the stable rock layer, that is, the anchor hole depth is greater than the thickness of the broken roof rock layer; 2.2: Send the anchor cable with the bag together with the anchoring agent roll into the bottom of the anchor cable hole. After the anchoring agent at the bottom of the hole breaks and solidifies, install the tray and lock, and apply a certain pre-tightening force to the anchor cable, so that the anchor cable is anchored in the stable rock layer above the broken roof rock layer; 2.3: Use the grouting pump station to pump the grouting slurry into the bag. The grouting slurry enters the bag through the grouting pipe arranged in the center of the steel strand. When the design pressure is reached or the pressure increases by 20% to 30%, the grouting is stopped. 2.4: When grouting is stopped, the pressure is maintained for a short time to ensure that the bag is fully expanded and compacts the surrounding fractured rock mass. The pressure can be released only after the internal grouting slurry solidifies.

4. The water-slurry displacement grouting method for breaking a water-rich roof according to claim 3, characterized in that: In step 2.3, whether to stop grouting is determined by monitoring the drainage volume. When the bag on the anchor cable squeezes the loose rocks around the hole wall, the drainage volume first increases and then decreases and approaches 0. When the drainage volume approaches 0, the grouting is stopped.

5. The water-slurry displacement grouting method for breaking a water-rich roof according to claim 4, characterized in that: The detailed method of step three is: 3.1: Construct several anchor holes in the shallow grouting area of ​​the tunnel roof, and the maximum depth of the anchor holes should be located in the deep water blocking area; 3.2: Install several grouting anchors on the top plate of the tunnel, and send them into the bottom of the anchor hole together with the anchoring agent roll. After the anchoring agent at the bottom of the hole breaks and solidifies, install the grouting plug in the front of the anchor, then install the tray and tighten the fastening nut. At this time, the fastening nut not only fixes the tray, but also applies a certain pre-tightening force to the grouting anchor; 3.3: Use the grouting pump station to carry out grouting construction on the grouting anchor rods, and adopt the low-pressure grouting method to make the grouting slurry diffuse from the shallow part to the deep part. When the pressure of the grouting pump station increases significantly, it means that the shallow grouting area has been fully filled with the grouting slurry. At this time, stop the grouting construction.

6. The water-slurry displacement grouting method for breaking a water-rich roof according to claim 5, characterized in that: The drainage holes, anchor cable holes and anchor rod holes are arranged alternately on the same cross section, or are arranged alternately within a certain spatial range to form regional water-slurry replacement.

7. A bag anchor cable used in the water-slurry displacement grouting method for a broken water-rich roof as claimed in any one of claims 1 to 6, comprising a lock, a tray and an anchor cable body formed by steel strands, characterized in that: A grouting bag is sleeved on the free section of the anchor body near the bottom of the hole, and both ends of the grouting bag are fixedly connected to the anchor body through steel sealing rings, and the outer diameter of the sealing ring is adapted to the inner diameter of the anchor hole; the steel strands of the anchor body are arranged in a blooming shape inside the grouting bag, and a grouting pipe passes through the center of the anchor body, and the grouting outlet of the grouting pipe is located at the blooming shape arrangement of the steel strands; the material of the grouting bag is required to have rigid supporting force when filled and be in an amorphous state after being emptied.

8. The bladder anchor as claimed in claim 7, characterized in that: The grouting bag is a high-strength and pressure-resistant flexible fabric.

9. The bladder anchor as claimed in claim 8, characterized in that: The grouting bag is made of high-strength polyester fiber.

10. The bladder anchor as claimed in claim 7, characterized in that: A groove is processed on the end surface of the steel sealing ring, and the end of the grouting bag is embedded in the groove, and the axial slip of the grouting bag is prevented by mechanical bite.

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