Grouting treatment process for strong water diversion area of karst fracture zone of over-unconsolidated formation

Abstract

The invention relates to the technical field of drilling grouting, in particular to an over-unconsolidated formation karst fracture zone strong water diversion area grouting treatment process which comprises the following steps that a treatment area is determined; a plurality of rows of drill holes are arranged in a quincunx staggered mode, the drill holes are drilled to the set depth d in a vertical descending mode, and the drill hole spacing S and the densified drill hole spacing S'exist between the multiple rows of drill holes arranged in the quincunx staggered mode; a grouting process is formulated for a strong water diversion area of the karst fracture zone of the over-loose stratum; a casing-following drilling process is adopted for drilling of the loose stratum; segmented and layered drilling is adopted for drilling of the strong water diversion area of the underlying karst fracture zone inside and outside the pit, and drilling is stopped when an abnormal geological structure occurs. Grouting operation is carried out; and evaluating and monitoring the grouting effect. The problems that in-construction underground engineering unconsolidated strata are not prone to hole forming, the reinforcing effect is poor, and foundation pit water bursting disasters are caused by underlying karst fracture zones can be solved.

Description

Technical Field

[0001] The invention relates to the technical field of drilling grouting, and in particular to a grouting treatment process for a strong water-conducting area in a karst fracture zone of an overly loose stratum. Background Art

[0002] In the process of urban subway construction in my country, the sites of shield shafts and stations are inevitably distributed with strata of different ages, different lithologies, different weathering degrees or different sequences, which manifests as differences in engineering geological properties in the vertical direction, especially when encountering geological structures such as fault fracture zones and karst caves. When the shield shaft and station foundation pit are excavated deeper, the excavation depth is lower than the groundwater level. In addition, frequent excavation disturbances cause the original strata to become unstable, which further causes the groundwater flow field to lose balance, forming a hydraulic gradient. The groundwater is conducted to the foundation pit along the structure, and water gushing occurs. And as the water gushing disaster continues to intensify, it is easy to cause the foundation pit wall to become unstable, or mechanical erosion of the pit wall rock, soil, and sandstone body occurs, resulting in sudden large-scale water gushing and flooding the foundation pit, which brings great difficulties to the construction. It is urgent to take effective treatment measures for the strong water-conducting areas of the shield shaft and station karst fracture zone containing loose strata based on the detailed on-site survey and refined exploration conclusions and combined with the hydrogeological data of the region to solve the current situation of passive drainage. Summary of the invention

[0003] The purpose of the present invention is to provide a grouting treatment process for strong water-conducting areas in loose strata karst fractured zones, which can solve the problems of difficult drilling and poor reinforcement effects in loose strata such as thick soil layers, thick sandy soil layers, and quicksand layers in underground projects under construction, as well as water gushing disasters in foundation pits caused by underlying karst fractured zones.

[0004] The technical solution of the present invention is achieved in this way:

[0005] A grouting treatment process for a strong water-conducting area in a karst fracture zone of a loose stratum comprises the following steps:

[0006] S1. Determine the treatment area: Determine the treatment area based on the detailed on-site survey and refined exploration conclusions and combined with the hydrogeological data of the area. The treatment area includes loose rock layers and the strong water-conducting areas of the underlying karst fractured zones inside and outside the pit;

[0007] S2. Formulate drilling arrangement parameters for the treatment area: set multiple rows of drill holes and arrange them in a staggered manner in a plum blossom shape, drill the holes vertically downward to a set depth d, and there are a drilling spacing S and an intensified drilling spacing S' between the multiple rows of drill holes arranged in a staggered manner in a plum blossom shape;

[0008] S3. Formulate a grouting process for the strong water-conducting area in the karst fracture zone of the loose strata. The grouting process adopts the first-pipe layer-injection grouting process: the follow-pipe drilling process is adopted for the drilling holes in the loose strata; the drilling in sections and layers is adopted for the drilling holes in the strong water-conducting area of ​​the underlying karst fracture zone inside and outside the pit, and the drilling is stopped when encountering abnormal geological structures;

[0009] S4, perform grouting operation;

[0010] S5. Evaluation and monitoring of grouting effect.

[0011] Further, in step S2, the borehole spacing S is 2 m, the dense borehole spacing S' is 1 m, and the set borehole depth d is determined according to the structural layer found in the hydrogeological data;

[0012] The drilling arrangement parameters for loose rock formations are: multiple rows of holes are arranged in a staggered plum blossom shape to achieve filling and reinforcement of the overlying loose layer;

[0013] The drilling arrangement parameters for the strong water-conducting areas in the karst fracture zone are: multiple rows of holes are drilled inside and outside the pit and arranged in a plum blossom shape to achieve joint grouting inside and outside the pit to ensure rapid blocking of sudden water gushing in the pit.

[0014] Furthermore, in step S3, the process flow of the grouting process is as follows:

[0015] A1: Determine the hole position first;

[0016] A2: Then use the pipe drilling technology to drill through the overlying loose layer to the rock surface;

[0017] A3: Insert the wall protection tube;

[0018] A4: Insert the cannula;

[0019] A5: Encapsulated tube, sealed wall tube;

[0020] A6: Place the grouting guide tube;

[0021] A7: Install the pilot pipe grouting tee, wash the hole, and grout;

[0022] A8: After the pilot tube grouting process is completed, the pilot tube is taken out and the borehole is left to solidify;

[0023] A9: Drilling in the underlying rock strata is done in sections and layers, and drilling is stopped when encountering abnormal geological structures;

[0024] A10: Wash the hole, inject grout, and wait for solidification;

[0025] A11: Repeat steps A9 and A10;

[0026] A12: terminal foramen;

[0027] A13; Check the grouting quality;

[0028] A14: Acceptance.

[0029] Furthermore, in the follow-up pipe drilling process of step A2, the follow-up pipe is drilled to the rock surface, and a suitable pipe holder is selected according to the follow-up pipe hole diameter and the drill rod diameter, so that the follow-up pipe and the drill rod always remain in a vertical state during the drilling process to prevent the formed borehole from being deviated.

[0030] Further, in step 3, the primary borehole diameter is Φ, the follower pipe diameter is Φ', the orifice casing diameter is Φ" and is consistent with Φ, the wall protection pipe diameter is Φ1, the grouting steel pilot pipe diameter is Φ2, and the secondary borehole diameter is Φ3;

[0031] Satisfies: 0.8Φ≤Φ1≤0.85Φ, 0.5Φ≤Φ2≤0.6Φ, 0.65Φ≤Φ3≤0.75Φ.

[0032] Further, in step S3, the grouting sequence of the grouting process is:

[0033] B1: Based on the water diversion range inferred from the previous exploration and treatment area, blockade grouting is carried out at both ends to limit the flow direction of groundwater and prevent it from extending outward;

[0034] B2: Split grouting is carried out on the loose layer overlying the pit to fill and reinforce the loose strata and effectively control the ground uplift;

[0035] B3: Perform dynamic water sealing grouting on the underlying karst fracture zone outside the pit to displace the original filling medium in the fracture zone;

[0036] B4: Carry out top water blocking grouting at the water gushing points in the underlying karst fracture zone in the pit to further control the water gushing;

[0037] B5: In the strong water-conducting area of ​​the underlying karst fracture zone, joint grouting inside and outside the pit at the same layer is required to ensure that the internal and external grouting pressures are consistent.

[0038] Furthermore, in the grouting sequence, the drilling and grouting are performed in a skipped sequence, with cross grouting performed every 2 to 3 holes to ensure that the diffusion radius meets the set requirements.

[0039] Further, in step S3, the grouting pressure parameters are adjusted according to the formation characteristics;

[0040] Among them, the grouting pressure parameters of the overlying loose layer are: 0-10m section ≤0.5Mpa, 10-20m section ≤0.8Mpa, 20-30m section ≤1.5Mpa, 30-40m section ≤2.5Mpa.

[0041] The grouting pressure parameters of the strong water-conducting area of ​​the underlying karst fracture zone are: 40-50m section ≤2.5Mpa, 50-60m section ≤3Mpa, 60-70m section ≤3.5Mpa, 70-80m section ≤4Mpa.

[0042] Furthermore, the wall protection pipe is a polyethylene PE wall protection pipe, and the grouting pilot pipe is a multi-element unidirectional slurry outlet pipe.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] The present invention aims at the characteristics of water gushing from the underlying karst broken zone during the excavation of a subway shield shaft under construction containing a 40m thick overlying loose layer. After adopting the above-mentioned targeted innovative measures, the overlying loose stratum is consolidated and compacted, and the integrity is greatly enhanced, and the shield shaft, the station ground connection wall, and the rigid support in the pit are greatly protected; the water gushing from the foundation pit is effectively blocked, which accelerates the excavation progress of the subway shield shaft and the station under construction, and effectively avoids the problem of water gushing that may occur in the subsequent excavation of the foundation pit; the underlying karst broken zone is filled and compacted, which effectively curbs the settlement problem of structures and buildings in the extension direction of the broken zone; and a safe working environment is created for the construction of support beams of the shield shaft and the station and the subsequent excavation. It has broadened the technical approach for the construction technology of grouting to control water gushing in loose strata and karst broken zones in subways, mines, tunnels and other projects with similar geological conditions, and made detailed supplements to the application of chemical grouting materials in the field of water gushing control in subways under construction. It has good promotion prospects and can generally solve the problems of difficult pore formation and poor reinforcement effect in loose strata such as thick soil layers, thick sandy soil layers, and quicksand layers in underground projects under construction, as well as foundation pit water gushing disasters caused by underlying karst broken zones. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0046] Figure 1 It is a schematic diagram of the forward grouting in the prior art;

[0047] Figure 2 It is a schematic diagram of the backward grouting in the prior art;

[0048] Figure 3 It is a schematic diagram of the drilling arrangement scheme of the present invention;

[0049] Figure 4 It is a schematic diagram of the structure of the pipe fixing device of the present invention;

[0050] Figure 5aThis is a schematic diagram of the pilot pipe grouting structure of the present invention;

[0051] Figure 5b It is a schematic diagram of the layer-by-layer grouting structure of the present invention;

[0052] Figure 6 This is the pilot tube layer grouting flow chart of the present invention.

[0053] In the figure:

[0054] 1-follow-pipe drilling hole; 2-hole casing; 3-polyethylene PE wall protection pipe; 4-steel conduit; 5-sealing material; 6-conduit connector; 7-one-way slurry stop valve; 8-conduit slurry discharge hole; 9-wall protection pipe slurry discharge hole; 10-two-way slurry stop valve; 11-one-way rubber expansion ring; 12-primary conduit grouting tee; 13-A grouting pipe; 14-B grouting pipe; 15-pressure gauge; 16-layer-type grouting tee; 17-secondary drilling hole.

[0055] 21-upper platform of pipe holder; 22-pipe groove; 23-fixing slot; 24-fixing column; 25-anti-collision bearing; 26-lower platform of pipe holder. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0057] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0058] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0059] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0060] In addition, the terms "horizontal", "vertical", "overhanging" and the like do not mean that the components are required to be absolutely horizontal or overhanging, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0061] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0062] Some embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0063] Example 1

[0064] In view of the technical problems in the background technology, this embodiment provides a grouting treatment process for a strong water-conducting area in a karst fracture zone of a loose stratum, which comprises the following steps:

[0065] S1. Determine the treatment area: Determine the treatment area based on the detailed on-site survey and refined exploration conclusions and combined with the hydrogeological data of the area. The treatment area includes loose rock layers and the strong water-conducting areas of the underlying karst fractured zones inside and outside the pit;

[0066] S2. Formulate drilling arrangement parameters for the treatment area: set multiple rows of drill holes and arrange them in a staggered manner in a plum blossom shape, drill the holes vertically downward to a set depth d, and there are a drilling spacing S and an intensified drilling spacing S' between the multiple rows of drill holes arranged in a staggered manner in a plum blossom shape;

[0067] S3. Formulate a grouting process for the strong water-conducting area in the karst fracture zone of the loose strata. The grouting process adopts the first-pipe layer-injection grouting process: the follow-pipe drilling process is adopted for the drilling holes in the loose strata; the drilling in sections and layers is adopted for the drilling holes in the strong water-conducting area of ​​the underlying karst fracture zone inside and outside the pit, and the drilling is stopped when encountering abnormal geological structures;

[0068] S4, perform grouting operation;

[0069] S5. Evaluation and monitoring of grouting effect.

[0070] It should be noted that loose strata, or loose layers, loose rock layers, are composed of soil, sand, gravel, and pebble layers, etc., and belong to the overlying rock strata. The strong water-conducting area of ​​the underlying karst fractured zone inside and outside the pit is referred to as the strong water-conducting area of ​​the underlying karst fractured zone or the strong water-conducting area of ​​the karst fractured zone, which belongs to the underlying rock strata.

[0071] The present invention aims at the characteristics of water gushing from the underlying karst broken zone during the excavation of a subway shield shaft under construction containing a 40m thick overlying loose layer, and implements different drilling processes for different strata, specifically: the follow-pipe drilling process is adopted for drilling holes in loose rock strata, and segmented and layered drilling is adopted for drilling holes in strong water-conducting areas of the underlying karst broken zone inside and outside the pit, and drilling is stopped when encountering abnormal geological structures; after adopting the above-mentioned targeted innovative measures, the overlying loose strata are consolidated and compacted, and the integrity is greatly enhanced, and the shield shaft, the ground connection wall of the station, and the rigid support in the pit are greatly protected; the water gushing from the foundation pit is effectively blocked, which accelerates the excavation progress of the subway shield shaft and the station under construction, and effectively avoids the problem of water gushing that may occur in the subsequent excavation of the foundation pit; the underlying karst broken zone is filled and compacted, which effectively curbs the settlement problem of structures and buildings in the extension direction of the broken zone; and a safe working environment is created for the support beam construction and subsequent excavation of the shield shaft and the station. It has broadened the technical approach for the construction technology of grouting to control water gushing in loose strata and karst broken zones in subways, mines, tunnels and other projects with similar geological conditions, and made detailed supplements to the application of chemical grouting materials in the field of water gushing control in subways under construction. It has good promotion prospects and can generally solve the problems of difficult pore formation and poor reinforcement effect in loose strata such as thick soil layers, thick sandy soil layers, and quicksand layers in underground projects under construction, as well as foundation pit water gushing disasters caused by underlying karst broken zones.

[0072] Example 2

[0073] In view of the technical problems of the background technology, there are two methods of using forward grouting or backward grouting in the prior art, which are as follows:

[0074] Forward segmented grouting is a grouting technology with high feasibility for special conditions such as difficulty in drilling holes and large water inflow. It refers to a grouting method that adopts alternating drilling and injection operations when it is determined through advance detection that the water inflow in front of the tunnel is large or a large-scale unfavorable geological development is developed. That is, during construction, drilling and injection are carried out in an alternating manner of drilling and injection, that is, drilling a section, injecting a section, then drilling a section, and injecting a section again. The length of each drilling and grouting section is 3 to 5 meters. Forward segmented grouting can use water bag type grouting plugs or orifice pipe flanges to stop grouting. The process of forward grouting is as follows: Figure 1 shown.

[0075] Reverse grouting is a grouting method that aims at relatively good stratum conditions and can basically reach the designed drilling depth in one drilling. During the grouting process, the pressure is continuously retreated. Through continuous grouting, the grouting slurry can diffuse from the grouting channel to the outside to fill the cracks or enhance the compressive strength of the rock and soil. Reverse grouting requires the use of a special grouting pump to transmit the slurry pressure from the ground to the inside of the channel. A certain amount of slurry is first added to the grouting channel, and then the grouting is carried out in a backward direction, continuously retreating to achieve the effect of gradually filling the cracks in the channel. The use of backward grouting can significantly improve construction efficiency. The length of each grouting segment is 5 to 8m. The process of backward grouting is as follows: Figure 2 shown.

[0076] In summary, the disadvantages of forward grouting are:

[0077] ① The forward grouting adopts multiple drilling methods to treat the treatment area. The drilling volume is about 2.5 to 3 times the drilling volume. If there are loose strata such as soil and sand layers, repeated drilling is required to reinforce the strata to ensure the treatment effect. The drilling volume will be higher, making the drilling cost too high during the construction process;

[0078] ②During the construction process of forward grouting, the double-liquid slurry does not penetrate deep into the stratum. According to construction experience, due to the high pressure, large flow and ion erosion characteristics of water hazards in karst areas, the setting time of grouting materials is difficult to control and the retention rate is low. The double-liquid slurry is difficult to play an effective role in the strata below 40m, which seriously affects the plugging and reinforcement of deep karst channels. In addition, repeated grouting destroys the original stratum structure, easily causing ground bulging and cracking, and the grouting quality is low.

[0079] ③ In forward grouting in loose strata such as soil and sand layers, as the drill rod is pulled out, the filling medium of the loose layer continuously replenishes the drill rod withdrawal position, making it difficult for the slurry to flow downward, which has caused the overall surface to rise.

[0080] Disadvantages of backward grouting:

[0081] ① The backward grouting adopts a one-time hole-forming method, which has strict requirements on the operation process. Improper operation during the construction process may easily leave the grouting galvanized pipe in the hole, resulting in waste holes and increasing construction costs;

[0082] ② The continuity of the backward grouting operation is not high, which affects the smoothness of the operation. If the first grouting effect is not ideal, the second supplementary reinforcement needs to repeat the first construction steps, which increases the construction cost.

[0083] This embodiment takes the shield shaft of a station under construction in Guangzhou as an example. The line runs from east to west, passing under a station of existing Line 14, existing Line 3, shield sections of intercity lines and urban villages and other building complexes. There are 1 shield shaft, 2 vertical shafts and 9 communication passages in the section. The exposed strata are: artificial fill layer (mixed fill, plain fill), alluvial layer (medium coarse sand layer, gravel sand layer, plastic silty clay, hard plastic silty clay), residual soil layer (plastic residual silty clay), and the underlying bedrock is the strongly weathered limestone conglomerate, medium weathered limestone conglomerate and slightly weathered limestone conglomerate of the Xinzhuang Formation (E1x) of the Paleogene. The burial depth of the bedrock surface on the left side along the mileage direction changes little, the bedrock surface fluctuates little, and the burial depth of the bedrock surface is 22.00~31.70m; the caves mostly appear in the middle of the site, mostly in a beaded distribution, and there are fewer caves on both sides. The depth of the bedrock surface on the right side along the mileage direction is increasing, the bedrock surface is undulating, and the depth of the bedrock surface is 21.60-37.50m; the caves in the middle are thicker and have good connectivity; the caves at the mileage ends are mostly distributed in a beaded shape, and the cave thickness is smaller. Karst is strongly developed, among which the average cave rate of limestone formations is 88%, the average cave height is 2.86m, and the average cave rate of conglomerate formations is 80.0%, and the average cave height is 3.90m.

[0084] The shield well has a daily water inflow of more than 14,000 m 3 After nearly two months of grouting and plugging, the expected effect could not be achieved, resulting in the inability to construct the shield well normally. In addition, the pressure of drainage and pumping increased, and the current situation seriously affected the safe excavation of the shield well. Based on the preliminary on-site survey and the preliminary construction situation, effective plugging measures were taken to cross the loose strata of the shield well and target the strong water-conducting area of ​​the underlying karst fracture zone to change the current passive situation.

[0085] This embodiment not only addresses the problems mentioned in the background technology, but also addresses the problems existing in the forward grouting and the backward grouting, and proposes an innovative technical solution to solve the practical problems in the shield shaft of the above-mentioned station under construction to ensure the grouting treatment effect, as follows:

[0086] Reference Figure 3-Figure 6 A grouting treatment process for a strong water-conducting area in a karst fracture zone of a loose stratum comprises the following steps:

[0087] S1. Determine the treatment area: Determine the treatment area based on the detailed on-site survey and refined exploration conclusions and combined with the hydrogeological data of the area. The treatment area includes loose rock layers and the strong water-conducting areas of the underlying karst fractured zones inside and outside the pit;

[0088] S2. Formulate drilling arrangement parameters for the treatment area: set multiple rows of drill holes and arrange them in a staggered manner in a plum blossom shape, drill the holes vertically downward to a set depth d, and there are a drilling spacing S and an intensified drilling spacing S' between the multiple rows of drill holes arranged in a staggered manner in a plum blossom shape;

[0089] S3. Formulate a grouting process for the strong water-conducting area in the karst fracture zone of the loose strata. The grouting process adopts the first-pipe layer-injection grouting process: the follow-pipe drilling process is adopted for the drilling holes in the loose strata; the drilling in sections and layers is adopted for the drilling holes in the strong water-conducting area of ​​the underlying karst fracture zone inside and outside the pit, and the drilling is stopped when encountering abnormal geological structures;

[0090] S4, perform grouting operation;

[0091] S5. Evaluation and monitoring of grouting effect.

[0092] In step S1, according to the conclusions of detailed on-site survey and refined exploration and combined with the hydrogeological data of the region, the range above 31.7m to 37.5m from the bedrock surface is a loose layer, mainly composed of quicksand layer, soil layer and sand layer, and it is difficult to form a hole. The range of 80m from the bedrock surface is a karst fracture development area, with two water diversion positions, the upper water diversion position is located at 57m to 62m, and the lower water diversion position is located at 72m to 78m.

[0093] Therefore, in step S1, the treatment area includes loose rock layers such as thick soil layers, thick sand layers, quicksand layers outside the pit and strong water-conducting areas of karst fractured zones underneath the pit.

[0094] In step S2, different drilling arrangement parameters are specified for different areas inside and outside the pit. Grouting drilling parameters include drilling arrangement mode, spacing, hole diameter, hole depth, etc. For drilling arrangement parameters, equal spacing arrangement is often used in the past, and parameters such as hole diameter and hole depth remain unchanged. However, the on-site geological conditions are complex. If unreasonable treatment measures are formulated, the grouting effect is not good.

[0095] The drilling arrangement parameters for the treatment area inside and outside the pit of the present invention are: all vertical downward drilling, multiple rows of drilling holes are arranged in a staggered plum blossom shape, the drilling spacing S is 2m, the dense drilling spacing S' is 1m, the drilling is vertical downward drilling, and the drilling design depth d is determined by the structural layer found in the hydrogeological data, and is dynamically adjusted during the construction process. The same row of drilling holes inside and outside the pit is arranged in a staggered depth, which greatly improves the formation integrity and the blocking effect of the water channel.

[0096] As an example, Figure 3As shown, the horizontal spacing between adjacent boreholes in each row (borehole spacing) is 2m. The boreholes can be intensified later according to the treatment situation, and the spacing between intensified boreholes is 1m, that is, the previous row and the next row are offset by 1m. The horizontal spacing of each row is the same, arranged in a plum blossom shape. Furthermore, the horizontal distance between the first row of boreholes outside the pit and the ground connection wall of the shield shaft is 5m, the spacing between the first row and the second row is 3m, the spacing between the second row and the third row is 4m, and the drilling depth is 72m (the drilling depth is dynamically adjusted according to the drilling exposure of the formation); the spacing between each row of boreholes in the pit is 2m, and the drilling depth is 37m (the drilling depth is dynamically adjusted according to the drilling exposure of the formation).

[0097] The above data are all drilling arrangement parameters set for this embodiment according to the conditions of the treatment area and shall not be used as limitations on this application. Those skilled in the art may adjust the above parameters according to actual engineering conditions and different treatment area conditions.

[0098] The drilling arrangement parameters of the present invention for loose rock layers such as overlying thick soil layers, thick sand layers, and quicksand layers are as follows: drilling in this area is extremely difficult and easy to collapse, and it is preferred to use the pipe drilling process for drilling, so the wall protection pipe flower holes are staggered to ensure that the slurry is evenly diffused and the consolidation body is complete and firm. Multiple rows of drill holes are staggered in a plum blossom shape to achieve filling and reinforcement of the overlying loose layer.

[0099] The drilling arrangement parameters for the strong water-conducting area of ​​the underlying karst fracture zone are as follows: the geological conditions of this layer are complex and the karst structure is well developed. It is preferred to use segmented and layered drilling. When encountering abnormal geological structures, drilling is stopped and grouting is carried out to ensure the effect of blocking water inrush. Multiple rows of holes are arranged in a plum blossom shape inside and outside the pit to achieve joint grouting inside and outside the pit to ensure rapid blocking of sudden water inrush in the pit.

[0100] The protective wall pipe is preferably made of polyethylene PE protective wall pipe, and the grouting conduit is a multi-element one-way grouting pipe with a suitable diameter that can be selected according to the change of the engineering environment. During grouting, the pressure will open the rubber sleeve outside the small hole of the protective wall pipe through the conduit, and the slurry will enter the formation. If the pressure outside the protective wall pipe is greater than that inside the pipe, the rubber sleeve outside the small hole will automatically close. It is placed on the bedrock surface, and high-pressure grouting is performed by mixing the slurry orifice, so that the slurry can be cemented and solidified at the abnormal structure of the underlying rock formation, and the overlying loose layer is reinforced by grouting in the early stage to reduce the ground uplift and cracking caused by the upward transmission of the grouting pressure, so as to achieve the goal of efficient, safe and convenient water gushing plugging.

[0101] As described above, the present invention adopts different drilling arrangement parameters to carry out targeted comprehensive grouting treatment for complex geological conditions such as loose rock strata such as overlying thick soil layers, thick sand layers, quicksand layers, and underlying karst fractured zones, highlighting the purpose of dynamically adjusting drilling parameters under special geological conditions to achieve significant grouting effects.

[0102] Furthermore, in step S3, the technicians formulate different grouting parameters for different treatment areas. Grouting parameters generally include grouting sequence, grouting pressure, diffusion radius, single hole grouting volume, etc. The traditional approach is to only measure whether the single hole grouting volume reaches the design value to decide whether to terminate grouting. The grouting saturation is insufficient in places with large cracks, the floating loose layer is dense, the cracks are small, and excessive grouting is easy to damage the integrity of the surrounding rock twice, which is relatively blind and the grouting effect is difficult to guarantee.

[0103] The grouting process of the present invention is innovative in three aspects: grouting pressure, grouting sequence, and grouting materials, as follows:

[0104] First, the grouting pressure innovation of the grouting process:

[0105] The grouting pressure parameters of the overlying loose layer are: 0-10m section ≤0.5Mpa, 10-20m section ≤0.8Mpa, 20-30m section ≤1.5Mpa, 30-40m section ≤2.5Mpa.

[0106] The grouting pressure parameters of the strong water-conducting area of ​​the underlying karst fracture zone are: 40-50m section ≤2.5Mpa, 50-60m section ≤3Mpa, 60-70m section ≤3.5Mpa, 70-80m section ≤4Mpa, etc. The grouting pressure increases successively with the depth section.

[0107] Secondly, the process flow of the grouting process is:

[0108] A1: Determine the hole position first;

[0109] A2: Then use the pipe drilling technology to drill through the overlying loose layer to the rock surface;

[0110] A3: Insert the wall protection tube;

[0111] A4: Insert the cannula;

[0112] A5: Encapsulated tube, sealed wall tube;

[0113] A6: Place the grouting guide tube;

[0114] A7: Install the pilot pipe grouting tee, wash the hole, and grout;

[0115] A8: After the pilot tube grouting process is completed, the pilot tube is taken out and the borehole is left to solidify;

[0116] A9: Drilling in the underlying rock strata is done in sections and layers, and drilling is stopped when encountering abnormal geological structures;

[0117] A10: Wash the hole, inject grout, and wait for solidification;

[0118] A11: Repeat steps A9 and A10;

[0119] A12: terminal foramen;

[0120] A13; Check the grouting quality;

[0121] A14: Acceptance.

[0122] Figure 5a and Figure 5b This is a diagram of the pilot tube layer-by-layer grouting structure of the present invention. Figure 5a This is the structure diagram of the first pipe grouting. Figure 5b The invention discloses a layer-by-layer grouting structure, which comprises: a follow-pipe drilling hole 1, an orifice casing 2, a polyethylene PE wall protection pipe 3, a steel conduit 4, a sealing material 5, a conduit connector 6, a one-way slurry stop valve 7, a conduit slurry discharge hole 8, a wall protection pipe slurry discharge hole 9, a two-way slurry stop valve 10, a one-way rubber expansion ring 11, a pilot conduit grouting tee 12, an A grouting pipe 13, a B grouting pipe 14, a pressure gauge 15, a layer-by-layer grouting tee 16, and a secondary borehole 17. Figure 6 The present invention is a pilot tube layer type grouting flow chart.

[0123] The grouting sequence of the grouting process is:

[0124] B1: Based on the water diversion range inferred from the previous exploration and treatment area, blockade grouting is carried out at both ends to limit the flow direction of groundwater and prevent it from extending outward;

[0125] B2: Split grouting is carried out on the loose layer overlying the pit to fill and reinforce the loose strata and effectively control the ground uplift;

[0126] B3: Perform dynamic water sealing grouting on the underlying karst fracture zone outside the pit to displace the original filling medium in the fracture zone;

[0127] B4: Carry out top water blocking grouting at the water gushing points in the underlying karst fracture zone in the pit to further control the water gushing;

[0128] B5: In the strong water-conducting area of ​​the underlying karst fracture zone, joint grouting inside and outside the pit at the same layer is required to ensure that the internal and external grouting pressures are consistent.

[0129] It should be noted that in each step of the grouting sequence, the order of drilling holes and drilling grouting is skipped, with cross grouting every 2 to 3 holes to ensure that the diffusion radius meets the set requirements and the slurry is evenly diffused.

[0130] Again, innovation in grouting material application:

[0131] Among them, for loose rock layers such as overlying thick soil layers, thick sand layers, and quicksand layers, PO42.5 water single-liquid grouting material is mainly used. According to the grouting volume and grouting pressure, a new type of cement-based anti-dispersion micro-expansion grouting material (hereinafter referred to as CIS) is used to control the slurry diffusion range, quickly bond and solidify with the surrounding loose layers, realize the filling and reinforcement of the surrounding rock, and enhance the overall strength of the consolidated body.

[0132] Among them, for the strong water-conducting area of ​​the karst fracture zone beneath the pit, PO42.5 water single-liquid slurry-CIS double-liquid slurry is used. The two can react quickly after mixing. The subsequent slurry continuously pushes the previous slurry to fill the karst fissures, and can adjust its coagulation time according to specific working conditions to achieve anti-scouring and anti-dispersion under dynamic water conditions, improve slurry retention rate, and block water gushing.

[0133] Among them, polyurethane material is used for water gushing points in the pit. After its mixed reaction, it can quickly penetrate into the karst voids, diffuse and expand, so as to achieve intermittent balance of water pressure inside and outside the pit, and cooperate with grouting outside the pit to completely block the water gushing points.

[0134] In the following pipe drilling process of step A2, the following pipe is drilled to the rock surface, and a suitable pipe fixer is selected according to the following pipe hole diameter and the drill rod diameter, so that the following pipe and the drill rod are always kept in a vertical state during the drilling process, and the formed borehole is prevented from being deflected. Specifically: In the following pipe drilling process, high-efficiency drilling equipment is selected, the following pipe is drilled to the rock surface, and the fixing effect of the following pipe and the drill rod is improved, and a suitable pipe fixer is selected according to the following pipe hole diameter and the drill rod diameter, so that the following pipe and the drill rod are always kept in a vertical state during the drilling process, and the formed borehole is prevented from being deflected.

[0135] In this embodiment, the structure of the pipe holder is as follows: Figure 4 As shown, it includes an upper platform 21 of the pipe holder, a pipe groove 22 for following the pipe, a fixing groove 23, a fixing column 24, an anti-collision bearing 25, and a lower platform 26 of the pipe holder.

[0136] In step 3, the primary borehole diameter Φ is determined according to the actual project, the follower pipe diameter Φ', the orifice casing diameter Φ" is consistent with Φ, the wall protection pipe diameter is Φ1, the grouting steel pilot pipe diameter is Φ2, and the secondary borehole diameter Φ3 is determined according to the primary borehole diameter Φ; satisfying: 0.8Φ≤Φ1≤0.85Φ, 0.5Φ≤Φ2≤0.6Φ, 0.65Φ≤Φ3≤0.75Φ.

[0137] In step S3, the first tube grouting is for the grouting of the overlying loose rock layer, which is mainly composed of polyethylene PE wall protection pipe, rubber sleeve, plug, joint (connection method is to use hot melter for welding), grouting tube, and grouting tee; the layer-by-layer grouting is to carry out segmented and layered grouting of the underlying rock layer. While ensuring the enrichment and reinforcement of the overlying loose strata and reducing the ground uplift and cracking, the underlying karst fracture zone is managed in layers, and grouting can be repeated.

[0138] In step S3, the polyethylene PE protective wall pipe and the grouting conduit are multi-element one-way slurry outlet pipes with suitable diameters that can be selected according to the changes in the engineering environment. During grouting, the pressure passes through the conduit to open the rubber sleeve outside the small hole of the protective wall pipe, and the slurry enters the formation. If the pressure outside the protective wall pipe is greater than that inside the pipe, the rubber sleeve outside the small hole automatically closes.

[0139] In step S3, different stratum porosities, filling coefficients, etc. are determined for different treatment areas and grouting materials with different proportions are used.

[0140] This application aims at the treatment of loose rock strata such as overlying thick soil layers, thick sand layers, quicksand layers, and water-conducting areas of underlying karst fractured zones. Different grouting materials are used for comprehensive treatment in combination with specific working conditions, so as to achieve the purpose of joint treatment inside and outside pits of projects such as subways and shield shafts, and ensure the grouting effect.

[0141] In summary, this application targets special geological conditions such as loose rock layers such as thick soil layers, thick sand layers, and quicksand layers, and water-conducting areas of underlying karst broken zones. When the fault is exposed to form loose layers and broken zones of varying degrees, more targeted regional comprehensive grouting treatment is carried out by flexibly adjusting various grouting parameters, highlighting the significant grouting effect of flexible and changeable grouting parameters under special geological conditions.

[0142] This application targets the water-conducting characteristics of loose rock strata such as overlying thick soil layers, thick sand layers, and quicksand layers, and the underlying karst broken zone. After adopting the above-mentioned targeted innovative measures, the integrity of the coal wall of the working face is greatly enhanced, the loose coal and rock mass is consolidated and dense, and the integrity is greatly enhanced. A regenerated cemented false roof support layer is quickly constructed on the support top beam, which alleviates the destructive impact of the roof falling again on the working face support, and creates a relatively safe working environment for the timely support operation after the coal mining machine drum cutting. The overlying loose strata are consolidated and dense, and the integrity is greatly enhanced. The shield shaft, the station ground connection wall, and the rigid support in the pit are greatly protected; the water gushing from the foundation pit can be effectively blocked, which accelerates the excavation progress of the subway shield shaft and station under construction, and effectively avoids the water gushing problem that may occur in the subsequent excavation of the foundation pit; the underlying karst broken zone is filled and dense, which effectively curbs the settlement of structures and buildings in the extension direction of the broken zone; and creates a safe working environment for the construction of support beams and subsequent excavation of shield shafts and stations. It has broadened the technical approach for the construction technology of grouting to control water gushing in loose karst broken zones in subways, mines, tunnels and other projects with similar geological conditions, and made detailed supplements to the application of chemical grouting materials in the field of water gushing control in subways under construction. It has good promotion prospects and outstanding economic and social benefits.

[0143] Compared with the forward grouting process, the present application has the following advantages: 1. It has a good effect on the reinforcement of loose strata such as soil layers and sand layers, and can save a lot of re-drilling work while ensuring the construction quality, thereby saving the project cost; 2. Compared with the forward grouting process in which the slurry is injected into the original stratum, the inner wall of the borehole is uneven or pulled out with the drill rod, and the loose layer medium continuously replenishes the borehole position, slowing down the impact potential energy of the slurry, which is prone to wall hanging and accumulation. The present invention adds a wall protection tube process, and the inner wall of the wall protection tube is smooth, which can enable the slurry to effectively reach the designated layer.

[0144] Compared with the backward grouting process, this application has the following advantages: continuous construction can be achieved for complex strata, multiple re-drilling can be performed, construction progress can be guaranteed, and construction costs can be saved.

[0145] The beneficial effects of the technical solution of the present invention are:

[0146] 1. The overlying loose strata are consolidated and compacted, and the integrity is greatly enhanced. The shield shaft, station ground connection wall, and rigid support in the pit are greatly protected;

[0147] 2. The underlying karst fracture zone is densely filled, effectively curbing the settlement of structures and buildings in the extension direction of the fracture zone;

[0148] 3. The water inrush from the foundation pit was effectively blocked, which accelerated the excavation progress of the subway shield shaft and station under construction, and effectively avoided the water inrush problem that might occur in the subsequent excavation of the foundation pit;

[0149] 4. It saves construction costs, shortens construction period, reduces construction pressure, and creates a safe working environment for the construction of shield shafts, station support beams and subsequent excavation.

[0150] The present invention is aimed at the characteristics of water gushing from the underlying karst broken zone during the excavation of underground projects such as subway shield shafts under construction containing 40m thick overlying loose layers. After adopting the above-mentioned targeted innovative measures, the overlying loose strata are consolidated and compacted, and the integrity is greatly enhanced. The shield shaft, the ground-connected wall of the station, and the rigid support in the pit are greatly protected; the water gushing from the foundation pit can be effectively blocked, which accelerates the excavation progress of the subway shield shaft and the station under construction, and effectively avoids the water gushing problem that may occur in the subsequent excavation of the foundation pit; the underlying karst broken zone is filled and compacted, which effectively curbs the settlement of structures and buildings in the extension direction of the broken zone; and creates a safe working environment for the construction of support beams and subsequent excavation of shield shafts and stations. It broadens the technical approach for the construction process of water gushing grouting treatment of loose strata karst broken zones in subways, mines, tunnels and other projects with the same geological conditions, and makes a detailed supplement to the application of chemical grouting materials in the field of water gushing treatment in subways under construction, which has a good promotion prospect.

[0151] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A grouting treatment process for strong water-conducting areas in karst fractured zones of loose strata, characterized in that: The following steps are involved: S1. Determine the treatment area: Determine the treatment area based on the detailed on-site survey and refined exploration conclusions and the hydrogeological data of the area. The treatment area includes loose rock layers and the strong water-conducting areas of the underlying karst fractured zones inside and outside the pit; S2. Formulate drilling arrangement parameters for the treatment area: set multiple rows of drill holes and arrange them in a staggered manner in a plum blossom shape, drill the holes vertically downward to a set depth d, and there are a drilling spacing S and an intensified drilling spacing S' between the multiple rows of drill holes arranged in a staggered manner in a plum blossom shape; S3. Formulate a grouting process for the strong water-conducting area in the karst fracture zone of the loose strata. The grouting process adopts the first-pipe layer-injection grouting process: the follow-pipe drilling process is adopted for the drilling holes in the loose strata; the drilling in sections and layers is adopted for the drilling holes in the strong water-conducting area of ​​the underlying karst fracture zone inside and outside the pit, and the drilling is stopped when encountering abnormal geological structures; S4, perform grouting operation; S5. Evaluation and monitoring of grouting effect.

2. The grouting treatment process for the strong water-conducting area in the karst fracture zone of the loose stratum according to claim 1 is characterized in that: In step S2, the borehole spacing S is 2 m, the dense borehole spacing S' is 1 m, and the set borehole depth d is determined according to the structural layer found in the hydrogeological data; The drilling arrangement parameters for loose rock formations are: multiple rows of holes are arranged in a staggered plum blossom shape to achieve filling and reinforcement of the overlying loose layer; The drilling arrangement parameters for the strong water-conducting areas in the karst fracture zone are: multiple rows of holes are drilled inside and outside the pit and arranged in a plum blossom shape to achieve joint grouting inside and outside the pit to ensure rapid blocking of sudden water gushing in the pit.

3. The grouting treatment process for the strong water-conducting area in the karst fracture zone of the loose stratum according to claim 1 is characterized in that: In step S3, the process flow of the grouting process is: A1: Determine the hole position first; A2: Then use the pipe drilling technology to drill through the overlying loose layer to the rock surface; A3: Insert the wall protection tube; A4: Insert the cannula; A5: Encapsulated tube, sealed wall tube; A6: Place the grouting guide tube; A7: Install the pilot pipe grouting tee, wash the hole, and grout; A8: After the pilot tube grouting process is completed, the pilot tube is taken out and the borehole is left to solidify; A9: Drilling in the underlying rock strata is done in sections and layers, and drilling is stopped when encountering abnormal geological structures; A10: Wash the hole, inject grout, and wait for solidification; A11: Repeat steps A9 and A10; A12: terminal foramen; A13; Check the grouting quality; A14: Acceptance.

4. The grouting treatment process for the strong water-conducting area in the karst fracture zone of the loose stratum according to claim 3 is characterized in that: In the follow-up pipe drilling process of step A2, the follow-up pipe is drilled to the rock surface, and a corresponding pipe fixer is selected according to the follow-up pipe hole diameter and the drill rod diameter, so that the follow-up pipe and the drill rod are always kept in a vertical state during the drilling process to prevent the formed borehole from being deflected.

5. The grouting treatment process for the strong water-conducting area in the karst fracture zone of the loose stratum according to claim 1 is characterized in that: In step 3, the primary borehole diameter is Φ, the follower pipe diameter is Φ', the orifice casing diameter is Φ" and is consistent with Φ, the wall protection pipe diameter is Φ1, the grouting steel pilot pipe diameter is Φ2, and the secondary borehole diameter is Φ3; Satisfies: 0.8Φ≤Φ1≤0.85Φ, 0.5Φ≤Φ2≤0.6Φ, 0.65Φ≤Φ3≤0.75Φ.

6. The grouting treatment process for the strong water-conducting area in the karst fracture zone of the loose stratum according to claim 1 is characterized in that: In step S3, the grouting sequence of the grouting process is: B1: Based on the water diversion range inferred from the previous exploration and treatment area, blockade grouting is carried out at both ends to limit the flow direction of groundwater and prevent it from extending outward; B2: Split grouting is carried out on the loose layer overlying the pit to fill and reinforce the loose strata and effectively control the ground uplift; B3: Perform dynamic water sealing grouting on the underlying karst fracture zone outside the pit to displace the original filling medium in the fracture zone; B4: Carry out top water blocking and grouting at the water gushing points in the underlying karst fracture zone in the pit to control the water gushing; B5: In the strong water-conducting area of ​​the underlying karst fracture zone, joint grouting inside and outside the pit at the same layer is required to ensure that the internal and external grouting pressures are consistent.

7. The grouting treatment process for the strong water-conducting area in the karst fracture zone of the loose stratum according to claim 6 is characterized in that: In the grouting sequence, the drilling and grouting sequence is skipped, with grouting performed crosswise at intervals of 2 to 3 holes to ensure that the diffusion radius meets the set requirements.

8. The grouting treatment process for the strong water-conducting area in the karst fracture zone of the loose stratum according to claim 1 is characterized in that: In step S3, the grouting pressure parameters are adjusted according to the formation characteristics; Among them, the grouting pressure parameters of the overlying loose layer are: 0-10m section ≤0.5Mpa, 10-20m section ≤0.8Mpa, 20-30m section ≤1.5Mpa, 30-40m section ≤2.5Mpa.

9. The grouting treatment process for the strong water-conducting area in the karst fracture zone of the loose stratum according to claim 8 is characterized in that: The grouting pressure parameters of the strong water-conducting area of ​​the underlying karst fracture zone are: 40-50m section ≤2.5Mpa, 50-60m section ≤3Mpa, 60-70m section ≤3.5Mpa, 70-80m section ≤4Mpa.

10. The grouting treatment process for the strong water-conducting area in the karst fracture zone of the loose stratum according to claim 3 is characterized in that: The wall protection pipe is a polyethylene PE wall protection pipe, and the grouting pilot pipe is a multi-element one-way slurry outlet pipe.

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