Karst cave filling treatment method

Abstract

The invention relates to the technical field of karst treatment, and discloses a karst cave filling treatment method in order to solve the problems that in the prior art, the filling treatment effect is poor, and the construction period is long. After the boundaries of the karst caves are found through drilling, feeding drill holes are formed in the boundaries of the karst caves at the interval of 5 m and used for pumping concrete. The double-layer sleeve is installed after the feeding hole is formed, the bottom of the outer-layer sleeve is installed on the rock surface, and then the bottom of the inner-layer sleeve is installed in the karst cave, is smaller than or equal to 2 m away from the bottom of the karst cave and is smaller than or equal to 1 m away from filling in the cave. The inner casing pipe is connected to a concrete pump truck, concrete is pumped into the karst cave through the inner casing pipe, and a gap between the double-layer casing pipes can play a role in exhausting and draining. According to the karst cave filling treatment method, one-hole multi-casting treatment can be carried out on a plurality of string-bead karst caves in a mode of lifting pipes from bottom to top, meanwhile, concrete is pumped through a pressure pump, karst water and gas in the caves can be effectively discharged, and fillers in the caves are compacted. The construction period is greatly shortened; and the treatment effect is better.

Description

Technical Field

[0001] The invention relates to the technical field of karst treatment, in particular to a karst cave filling treatment method. Background Art

[0002] Karst is widely distributed in southern my country, and the more common karst forms include caves, karst fissures, and karst gullies. Caves will affect the distribution of ground stress around the soil. When underground projects are located near caves or pass through caves, construction may cause karst collapse, deformation and collapse of supporting structures, sudden water and mud in the foundation pit, and other disasters, affecting the construction progress and structural safety, and polluting the ecological environment. As a key technology in subway construction, karst treatment is mainly carried out by filling and grouting underground proven caves to treat underground caves around foundation pits and retaining structures. In karst treatment construction, cave treatment is often carried out in the form of filling concrete or cement mortar and grouting. After treatment, the cave has a certain bearing capacity, which can minimize the risk of accidents such as cave collapse and surface subsidence during station (tunnel) construction. The risks of accidents such as structural, personnel or mechanical safety caused by surface subsidence can be minimized, so as to meet the bearing capacity, deformation, waterproofing and other requirements of the permanent structure of the station (tunnel). The commonly used filling methods at this stage are as follows: Figure 1 The figure shows the traditional karst treatment process of feeding, in which concrete or mortar pouring is called cave feeding. The current construction methods are as follows Figure 1 As shown:

[0003] ① After finding out the boundary of the cave, drill a hole with a diameter of 200 mm in the center of the cave;

[0004] ② For caves that need grouting, grouting holes with a spacing of 2mx2m are constructed to serve as exhaust holes. For caves that do not need grouting, exhaust holes are constructed at appropriate locations.

[0005] ③ Extend the PVC pipe into the top surface of the cave and fix it with a clamp on the ground, connect the concrete pump pipe to the feeding hole, and pour the concrete in by pumping;

[0006] ④After the concrete pouring is completed, use the sleeve valve pipe to supplement the grouting

[0007] like Figure 2 As shown, the feeding process is to pour concrete or mortar through the feeding hole, discharge the water in the cave through the surrounding exhaust holes, and fill the cavity with concrete or mortar. Since the fluidity of concrete is not as good as mortar, the sleeve valve pipe is used for grouting after concrete filling to achieve the effect of dense filling. However, there are the following problems:

[0008] ① Too idealistic. In the actual treatment process, the karst cave has a complex shape and is not an ellipse. When the vent hole is blocked by the filling material or concrete in the karst cave, the drainage and exhaust effect will be lost, resulting in poor filling treatment effect.

[0009] ② Most of the caves are in the shape of beads. If we want to ensure that they can be effectively filled, we have to construct multiple feeding holes, which will affect the cost and construction period;

[0010] ③The feeding pipe is made of PVC material, which has limited strength. The burial depth of the cave is generally between 30-40m, and it is easy to deform during the construction process.

[0011] ④ The feeding pipe extends into the cave top 0.5-1m, and the concrete or mortar mainly relies on its own weight to fill the cave. During the process of concrete being poured into the cave, the exhaust pipe will be blocked by the fillings and slurry of the cave. The drainage hole dredging effect is slow due to the weight of the concrete being pressed into the cave, and the overall karst treatment effect is reduced.

[0012] See also Figure 3 and Figure 4 It can be seen that the traditional karst treatment method has fillings in the cave that cannot be replaced, concrete is squeezed into other strata instead of entering the interior of the cave, and beaded caves need to be treated multiple times. This not only prolongs the construction period, but also easily leads to poor filling effects of the caves, and the continuity of the construction work cannot be guaranteed, resulting in an increase in project costs and a huge waste of resources, which slows down the input of concrete. Summary of the invention

[0013] The purpose of the present invention is to provide a cave filling treatment method to solve the shortcomings of the prior art. It can perform a continuous treatment once and is not restricted by the surrounding environment. There is no need to arrange exhaust holes around the filling hole to carry out treatment construction. It can greatly save construction time, avoid the impact on ground traffic as much as possible, and improve construction efficiency.

[0014] To achieve the above object, the present invention provides a cave filling treatment method, comprising the following steps:

[0015] (i) After the boundaries of the cave are explored, feeding holes are arranged at intervals of 5m within the boundaries of the cave.

[0016] (ii) After the drilling is completed, double-layer casing is installed, with the outer casing installed to the rock surface and the inner casing installed to a distance of ≤2m from the bottom of the cave and ≤1m from the height of the filling.

[0017] (III) Use the pump pipe connector to directly connect the top of the inner casing to the concrete pump truck, and fix the inner casing and the outer casing with a connecting clamp. Start the concrete pump truck and fill the cave with concrete through the inner casing.

[0018] (iv) After the concrete is pumped, grouting is added to the cave through the sleeve valve grouting pipe 5 to fill the gap between the concrete and the cave;

[0019] (5) After concrete pumping is completed, pull out the inner casing and the outer casing respectively, and clean them for reuse.

[0020] Principle of this treatment method

[0021] After drilling is completed, double-layer casing is installed, with the outer casing installed above the rock surface and the inner casing installed ≤2m from the bottom of the cave and ≤1m from the height of the filling.

[0022] The outer casing can protect, exhaust and replace the internal fillings. The inner casing is a high-pressure pump pipe with a pressure of up to 30Mpa, which allows the fillings such as concrete or cement mortar to completely enter the cave for filling and replace the fillings of the cave itself, or squeeze the remaining fillings tightly. When the exhaust hole is blocked, the karst water can still be discharged from the cave through the gap between the inner and outer casings, thereby filling the cave.

[0023] For beaded caves, one hole can be used for multiple purposes. First, the inner casing is lowered to the lowest cave for material filling. When the material filling is completed, the inner casing is lifted to the upper cave to continue feeding.

[0024] For caves with a height greater than 5m, the inner casing is first lowered to the bottom of the cave, with materials added in layers in sections of 2-3m to achieve a dense pouring effect and avoid concrete segregation.

[0025] At the same time, the inner and outer sleeves can be pulled out after the construction is completed and reused.

[0026] The cave filling treatment method provided by the present invention has the following advantages:

[0027] 1. When drilling reveals a string of beads of karst caves that cannot be treated in one go, this method can be used for one-time continuous treatment, greatly shortening the construction period and engineering costs, and there is no need to repeatedly drill holes after exposure to treat karst caves of different elevations;

[0028] 2. Compared with conventional filling methods, this method is not restricted by the surrounding environment and can carry out treatment construction without arranging exhaust holes around the filling holes. It can greatly save construction time, minimize the impact on ground traffic, and improve construction efficiency.

[0029] 3. In view of the situation that the upper strata of the cave are thick sand layers, it is very easy to cause sand layer loss when the casing is pulled out after filling is completed using conventional construction methods, resulting in major safety accidents such as ground collapse or machinery falling. In this method, the outer casing plays an effective protective role on the sand layer to avoid the above situation.

[0030] 4. When this method is used for filling construction, the inner casing can be continuously disassembled from the bottom of the cave to the top as the drilling rig or pump pipe rack is continuously disassembled, and the treatment effect is good. And as the pumping pressure continues to increase, the original filling inside the cave can be compacted to give it a certain bearing capacity.

[0031] 5. It is suitable for areas where karst is located under urban roads, where the karst treatment space is limited and the treatment time is required to be short.

[0032] Compared with the traditional method, the outer casing of the method can be inserted into the rock surface to protect the borehole wall from collapse. After entering the rock layer, there is no need to protect the wall of the feed material, so the outer casing can reach the rock surface. There are two diameters for feeding materials, φ127 and φ108. The large hole reaches the rock surface, and the small hole is drilled from the rock surface to the bottom of the cave at least 0.5m. The concrete is pumped into the cave with pressure through the inner casing. The gap between the two casings can serve as an exhaust hole, and there is no need to add an exhaust hole. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of pressurized cement grout injection for filling concrete;

[0034] Figure 2 This is a schematic diagram of karst treatment for traditional feeding;

[0035] Figure 3 This is a schematic diagram showing that the exhaust holes of heterogeneous caves are easily blocked;

[0036] Figure 4 Schematic diagram of the feeding holes that need to be constructed separately for the beaded caves;

[0037] Figure 5 A schematic diagram of karst treatment provided by the present invention;

[0038] Figure 6 A schematic diagram of high-pressure feeding provided by the present invention;

[0039] Figure 7 It is a schematic diagram of the positions of the outer casing, the inner casing, the first borehole, the cave, and the rock surface of the present invention;

[0040] Figure 8 This is a schematic diagram of treating beaded caves according to the present invention.

[0041] In the figure: 1 feeding hole, 2 outer casing, 3 inner casing, 4 grouting hole, 5 sleeve valve grouting pipe. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0043] Take the construction of an intercity railway station as an example. The project is located under the urban road. Karst treatment requires the enclosure of a certain range of road lanes. In order to minimize the impact on ground traffic, the karst treatment space is limited and the enclosure treatment time is required to be short. The surrounding environment is often affected and normal treatment cannot be carried out, which seriously reduces the subsequent construction efficiency.

[0044] According to the engineering geological conditions of the construction site itself, in order to solve the problems of intensive karst development in the station area, large cave volume and complex water channels between caves, the present invention provides a cave filling treatment method, which ensures the smooth excavation of the foundation pit and the safety of subsequent construction, and has obvious social and economic benefits.

[0045] See also Figures 5 to 8 The present invention provides a cave filling treatment method, comprising the following steps:

[0046] (i) After the boundaries of the cave are explored, feeding holes are arranged at intervals of 5m within the boundaries of the cave.

[0047] (ii) Installing double-layer casing: the outer diameter of the outer casing 2 is 127 mm, and the outer diameter of the inner casing 3 is 100 mm;

[0048] Insert the outer casing 2 into the feeding hole 1 and install it to the rock surface. Insert the inner casing 3 into the outer casing 2 and make the inner casing 3 penetrate into the cave and be ≤2m away from the bottom of the cave and ≤1m away from the filling material. The position between the inner casing 3 and the outer casing 2 is as follows: Figure 7 As shown;

[0049] The outer casing 2 can protect, exhaust and replace the internal fillings. The inner casing 3 high-pressure pump pipe enables the fillings such as concrete or cement mortar to completely enter the cave for filling treatment and replace the fillings of the cave itself, or compact the remaining fillings, so as to achieve the karst treatment design standards and reduce the risk of the subsequent station (tunnel) during construction.

[0050] The outer casing 2 and the inner casing 3 are fixed by a connecting clamp, and the connecting clamp is located above the ground; when the exhaust hole is blocked, the karst water can still be discharged from the cave through the gap between the inner and outer casings.

[0051] (III) Use the pump pipe connector to directly connect the top of the inner casing to the concrete pump truck, and use the clamp to fix the inner casing 3 and the outer casing 2. Start the concrete pump truck and fill the cave with concrete through the inner casing. The position relationship is as follows: Figure 7 As shown;

[0052] When the cave to be filled is a beaded cave, one hole can be used for multiple purposes, such as Figure 8As shown, the inner casing 3 needs to be lowered to the lowest cave for material feeding and filling. After the material feeding and filling are completed, the inner casing 3 is lifted up to the upper cave to continue feeding.

[0053] When the cave to be filled is a cave with a height greater than 5m, the inner casing 3 must be lowered to the bottom of the cave first, with 2-3m as a section, and the material is added layer by layer to achieve a dense pouring effect and avoid concrete segregation;

[0054] During the filling process, the water in the cave is discharged through the gap between the outer casing 2 and the inner casing 3; when the gap between the outer casing 2 and the inner casing 3 is also blocked, the delivery pressure of the concrete pump truck in the present invention is 30MPa. Therefore, in this case, the concrete pump truck can inject concrete into the cave under high pressure, and at the same time, the karst water is discharged through the channel connecting to other caves;

[0055] (iv) After the concrete is pumped, grouting is added to the cave through the sleeve valve grouting pipe 5 to fill the gap between the concrete and the cave;

[0056] (V) After filling, the outer sleeve 2 and the inner sleeve 3 are pulled out respectively for reuse.

[0057] It is worth noting that the outer casing 2 used in the present invention can play the role of protection, exhaust and replacement of internal fillings. The inner casing 3 is a high-pressure pump pipe, which enables the fillings such as concrete or cement mortar to completely enter the cave for filling treatment and replace the fillings of the cave itself, or squeeze the remaining fillings to compact, so as to achieve the karst treatment design standards and reduce the risk of the station (tunnel) during construction.

[0058] The cave filling treatment method provided by the present invention has the following advantages:

[0059] 1. When drilling reveals a string of beads of karst caves that cannot be treated in one go, this method can be used for one-time continuous treatment, greatly shortening the construction period and engineering costs, and there is no need to repeatedly drill holes after exposure to treat karst caves of different elevations;

[0060] 2. Compared with conventional filling methods, this method is not restricted by the surrounding environment and can carry out treatment construction without arranging exhaust holes around the filling holes. It can greatly save construction time, minimize the impact on ground traffic, and improve construction efficiency.

[0061] 3. In view of the situation that the upper strata of the cave are thick sand layers, it is very easy to cause sand layer loss when the casing is pulled out after filling is completed using conventional construction methods, resulting in major safety accidents such as ground collapse or machinery falling. In this method, the outer casing plays an effective protective role on the sand layer to avoid the above situation.

[0062] 4. When this method is used for filling construction, the inner casing can be continuously disassembled from the bottom of the cave to the top as the drilling rig or pump pipe rack is continuously disassembled, and the treatment effect is good. And as the pumping pressure continues to increase, the original filling inside the cave can be compacted to give it a certain bearing capacity.

[0063] 5. It is suitable for areas where karst is located under urban roads, where the karst treatment space is limited and the treatment time is required to be short.

[0064] Compared with the traditional method, the outer casing of the method can be inserted into the rock surface to protect the borehole wall from collapse. After entering the rock layer, there is no need to protect the wall of the feed material, so the outer casing can reach the rock surface. There are two diameters for feeding materials, φ127 and φ108. The large hole reaches the rock surface, and the small hole is drilled from the rock surface to the bottom of the cave at least 0.5m. The concrete is pumped into the cave with pressure through the inner casing. The gap between the two casings can serve as an exhaust hole, and there is no need to add an exhaust hole.

[0065] Compared with the traditional method, the outer casing of the method can be inserted into the rock surface to protect the borehole wall from collapse. After entering the rock layer, there is no need to protect the wall of the feed material, so the outer casing can reach the rock surface. There are two diameters for feeding materials, φ127 and φ108. The large hole reaches the rock surface, and the small hole is drilled from the rock surface to the bottom of the cave at least 0.5m. The concrete is pumped into the cave with pressure through the inner casing. The gap between the two casings can serve as an exhaust hole, and there is no need to add an exhaust hole.

[0066] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A cave filling treatment method, characterized in that , including the following steps: Step S10, after completing the cave exploration drilling, within the boundary of the cave that needs to be filled with concrete or mortar, the feeding drilling holes are arranged at a spacing of 5m to fill the cave, and the site is leveled and laid out, and the drilling rig is used to drill to the designed hole depth; Step S20, during the drilling process, two kinds of borehole drill bits are used, wherein a large-diameter drill bit is used for the part above the rock surface, and a small-diameter drill bit is used for the rock section. After drilling, a double-layer casing is installed, wherein both the inner and outer casings are steel casings; the bottom of the outer casing is installed to the rock surface, and the inner casing is installed to a distance of ≤2m from the bottom of the cave and ≤1m from the height of the filling; Step S30, connecting the top of the inner casing to the concrete pump truck through a pump pipe connector, and fixing the inner and outer casings at the drilled hole with a clamp; starting the concrete pump truck, and filling the cave with concrete using the inner casing to ensure that the concrete is filled evenly and fills the gaps inside the cave; Step S40, after the concrete is pumped, grouting is performed into the cave through the sleeve valve grouting pipe using the peripheral exploration holes to fill the gap between the concrete and the cave; Step S50, after the concrete pumping is completed, the inner casing and the outer casing are pulled out respectively, and cleaned for reuse.

2. A cave filling treatment method according to claim 1, characterized in that: In step S20, the double-layer casing processing method is as follows: The outer casing is only inserted into the rock surface to protect the stability of the borehole wall. After entering the rock formation, there is no need to protect the wall for feeding.

3. A cave filling treatment method according to claim 2, characterized in that: The inner casing adopts a small diameter and there is a gap between it and the outer casing. Concrete is pumped into the cave through the inner casing under pressure. The gap between the two casings serves as an exhaust hole. When the exhaust hole is blocked, karst water and gas can still be discharged from the cave through the gap between the inner and outer casings, thereby filling the cave.

4. A cave filling treatment method according to claim 3, characterized in that: The inner casing is connected and fixed to the outer casing by a clamp on the ground. The vertical position of the inner casing can be changed according to needs. For caves with larger cave heights, the inner casing is first lowered to the bottom of the cave, with 2-3m as a section, and materials are added in layers to achieve a dense pouring effect and avoid concrete segregation.

5. A cave filling treatment method according to claim 4, characterized in that: In particular, for beaded caves, the inner casing is first lowered to the lowest cave for material feeding and filling. When the material feeding and filling are completed, the inner casing is lifted to the upper cave to continue feeding.

6. A cave filling treatment method according to claim 5, characterized in that: The inner pipe is directly connected to a concrete pump truck, and the pressure provided by the concrete pump truck is used to perform high-pressure pumping and filling of the cave.

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