Construction method of fabricated mud pit for circulating cast-in-situ bored pile mud

Abstract

The invention relates to the technical field of cast-in-situ bored pile slurry circulation construction, in particular to a construction method of an assembly type slurry pool for cast-in-situ bored pile slurry circulation, which comprises the following steps: step 1, the assembly type slurry pool is divided into an assembly type sedimentation pool and an assembly type slurry storage pool for splicing structure design, and each component is blanked and processed in a field in advance; transporting to a site for installation; 2, the two ponds are independently assembled; 3, after assembly is completed, a closed water test is conducted; 4, the site is leveled, a foundation pit is excavated, and the two ponds are hoisted and communicated; 5, a slurry pump support is installed on the assembly type slurry storage pool, and a slurry pump and a pipeline are installed; and 6, after pile foundation construction is completed, mud and sediment in the assembly type mud pit are removed, and the mud pit is adjusted away through a crane to be used in the next construction site or disassembled and recycled for use. According to the construction method, modular design is adopted for the assembly type mud pit, transportation is convenient and fast, mud pits of different specifications and sizes can be assembled, the turnover utilization rate is high, and environmental pollution is small.

Description

Technical Field

[0001] This invention relates to the technical field of drilling mud circulation construction for bored cast-in-place piles, specifically a construction method for a prefabricated mud tank for drilling mud circulation in bored cast-in-place piles. Background Technology

[0002] In bridge construction, to increase the structural strength of bridge piles, wells are usually drilled in the foundation and piles are inserted into the wells to improve the structural strength of the piles. The mud circulation method is used in the drilling of bridge piles. Mud circulation plays a role in borehole wall protection, slag removal, drill bit cooling and lubrication, and stabilizing the water level in the hole. It is a key technology and core link in the pile formation process.

[0003] Mud pits provide storage space for the recycling of drilling mud. In the mud pit, drill cuttings carried from the borehole settle and are filtered, temporarily stored, and supplied to the mud pump so that new mud can be pumped into the borehole, thus achieving circulation. Traditional construction methods commonly employ extensive approaches such as excavating large mud pits and open-air dumping of drill cuttings. Open-air excavation of mud pits not only occupies a large amount of land, but also requires slope excavation, concrete sealing of the pit bottom, and mortar wall construction, resulting in long excavation cycles, increased construction costs, and risks such as mud leakage, spillage, and the spread of drill cuttings with rainwater, posing potential threats to the construction site and the surrounding ecological environment.

[0004] To improve the standardization of on-site civilized construction and the effectiveness of environmental and water conservation management, it is necessary to adopt certain technical measures to optimize traditional mud pits into easily installable and dismantled prefabricated structures. Therefore, it is necessary to provide a construction method for a prefabricated mud pit for drilling and grouting pile mud circulation to solve the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of this invention is to provide a construction method for a prefabricated mud pit for drilling and grouting pile mud circulation. This construction method for a prefabricated mud pit for drilling and grouting pile mud circulation adopts a modular design for the mud pit, which is convenient to transport and can be assembled into mud pits of different specifications and sizes. It has a high turnover rate and low environmental pollution. Compared with concrete mud pits, it effectively improves the level of on-site standardization and increases construction efficiency.

[0006] This invention is achieved using the following technical solution: A construction method for a prefabricated mud pit for drilling mud circulation in bored piles includes the following steps: Step 1: Fabrication and Transportation of Prefabricated Mud Tanks; The prefabricated mud tanks are designed as assembled structures, consisting of prefabricated sedimentation tanks and prefabricated storage tanks. Each component is pre-cut and fabricated on-site, and after surface treatment of the steel structure, it is transported to the site as unit components for installation. Specifically, after the prefabricated mud tank has passed structural design and strength calculations, each component is pre-cut and fabricated on-site. The dimensional accuracy, cutting quality, beveling, and hole position accuracy of each component are checked. Once the requirements are met, pre-assembly is carried out on-site. Pre-assembly ensures the matching of the connection nodes of the prefabricated mud tanks and verifies the overall structural dimensions.

[0007] Step 2: On-site assembly of the prefabricated mud tank; the prefabricated sedimentation tank and prefabricated slurry storage tank are assembled independently. Taking the on-site assembly of the prefabricated sedimentation tank as an example, firstly, the base plate is assembled. The segmented base plates are bolted together, and special sealing materials (such as expansive waterstop strips, rubber waterstops, etc.) are used at the joints between the base plates to ensure a tight connection. Then, each side plate unit is equipped with lifting lug holes. A truck crane is used to lift the side plates one by one into place. Each side plate is bolted to the adjacent base plate and side plate immediately after installation. During the installation of the side plates, diagonal braces or guy ropes can be used for temporary fixation to prevent the side plates from tipping over. Secondly, the internal supports are installed. Corner braces are installed at the four corners of the top beam of the prefabricated sedimentation tank in sequence to form a stable structure. Finally, all bolted connections, plate joints, and other areas where leakage may occur are filled or coated with oil-resistant and corrosion-resistant special sealing materials. The on-site assembly steps for the prefabricated slurry storage tank are the same as those for the prefabricated sedimentation tank, and will not be repeated here.

[0008] Step 3: Water tightness test of the prefabricated mud tank; After the prefabricated sedimentation tank and prefabricated slurry storage tank are assembled on site, a water tightness test should be conducted. Before the test, check the tank structure for obvious cracks and seepage points. During the test, slowly inject water into the sedimentation tank and observe the water level changes and seepage from the tank wall in stages. If there is leakage, mark the location, drain the water, and thoroughly repair the leak.

[0009] Step 4: Excavation and positioning of the mud pit foundation; after site leveling, mark the mud pit dimensions with lime according to the plan. Excavate the foundation pit vertically as much as possible; if the soil is unstable, sloping excavation can be used. After excavating the foundation pit, use a truck crane to lift the prefabricated sedimentation tank and prefabricated slurry storage tank into their designated positions inside the foundation pit, ensuring a tight fit between the two tanks. After hoisting into place, install expansion sealing strips in the connection opening to prevent slurry leakage. Backfill the area around the mud pit with earthwork and set up safety barriers and warning signs around it.

[0010] Step 5: Layout of the mud circulation system; Install the mud pump bracket on the prefabricated mud storage tank, and simultaneously arrange the mud pump and connect the circulation pipeline. Start the mud pump and conduct no-load and load tests to check whether the entire circulation path is unobstructed, whether each piece of equipment is working properly, and whether there are any leaks in the tank walls and interfaces. During drilling, the circulation of mud achieves functions such as wall protection and cuttings carrying.

[0011] Step 6, dismantling the mud pit; after the pile foundation construction is completed, promptly remove the mud and sediment from the prefabricated mud pit, and after being moved away by a crane, steps 4-5 can be repeated for the mud circulation construction of the remaining pier pile foundation bored piles; or it can be dismantled and recycled for the next use.

[0012] The prefabricated sedimentation tank and prefabricated slurry storage tank are bolted together as a single unit. The connecting surfaces of the prefabricated sedimentation tank and prefabricated slurry storage tank are provided with connecting ports. Both prefabricated sedimentation tanks and prefabricated slurry storage tanks include a square frame composed of purlins connected by bolts. The bottom and sides of the square frame are respectively fitted with a bottom plate and side plates via bolts for sealing connections. Sealing strips are laid at the joints of the bottom plate and side plates, and sealant is applied to the bolt holes to prevent leakage. A mud pump bracket is installed on the top of the square frame of the prefabricated slurry storage tank. After the prefabricated sedimentation tank and prefabricated slurry storage tank are assembled on-site, a water tightness test should be conducted. Before the test, check the tank structure for obvious cracks and seepage points. During the test, water is slowly injected into the sedimentation tank, and the water level changes and foresight of the tank walls are observed in stages. If leakage is found, the location is marked, and the leak is drained and thoroughly repaired. The prefabricated mud tank should be assembled strictly according to the assembly sequence provided in this technology. Forced assembly or disassembly is prohibited during the assembly process to avoid damaging the components and affecting reusability. Prefabricated mud tanks of different specifications and sizes can be assembled by adjusting the number of square frames, side plates, and bottom plates according to the required mud volume for drilling piles on site. Mud carrying rock cuttings back from the bottom of the bored piles passes through a prefabricated sedimentation tank to initially separate inferior, large-particle drill cuttings from the circulation system, reducing the burden on subsequent mechanical equipment purification. After initial settling in the prefabricated sedimentation tank, the mud enters a prefabricated storage tank through a connecting port. Various chemical additives, barite, or water are added to the prefabricated storage tank to maintain or adjust key performance indicators such as relative density, viscosity, and sand content. Qualified mud has a relative density of 1.05–1.2, a viscosity of 16–22s, and a sand content of 4–9%, storing qualified mud ready to be pumped into the bored pile holes. After the prefabricated mud tank passes structural design and strength calculations, each component is pre-cut and processed on site. The dimensional accuracy, cutting quality, beveling, and hole position accuracy of each component are checked, and pre-assembly is carried out on site after meeting the requirements. The prefabricated sedimentation tank is the first functional tank into which drilling mud carrying rock cuttings returned from the bottom of the bored piles enters. Due to the large volume of the prefabricated sedimentation tank, the flow rate of the mud is significantly reduced. Through its settling function, large, inferior drill cuttings that are detrimental to the mud's performance are initially separated from the circulation system, reducing the burden on subsequent mechanical purification equipment.

[0013] A further preferred embodiment: the four corners of the square frame are respectively connected to corner braces, each corner brace including a channel steel crossbar and ear plates. The ear plates are respectively fixedly installed at both ends of the channel steel crossbar, and the channel steel crossbar is connected to the square frame by bolts through the ear plates.

[0014] A further preferred embodiment: The top of the square frame is symmetrically provided with lifting lugs. To facilitate better overall hoisting, corresponding lifting lugs are also provided at the bottom of the square frame.

[0015] A further preferred embodiment: the connection between the prefabricated sedimentation tank and the prefabricated slurry storage tank is fitted with an expansion sealing strip, and the connection is sealed with a wire mesh filter.

[0016] A further preferred embodiment: the wire mesh is installed at the connection point by a pressure strip, which facilitates the maintenance and replacement of the wire mesh.

[0017] A further preferred embodiment: the top of the square frame of the prefabricated slurry storage tank is provided with a connecting base plate, and the slurry pump bracket is detachably connected to the connecting base plate with bolts. The slurry pump bracket consists of three adjustable-angle steel pipes, which can carry the slurry pump to form a slurry circulation system.

[0018] The construction method for the prefabricated mud pit used for mud circulation in bored piles has the following advantages: 1. The modular design of the prefabricated mud pit allows for assembly and disassembly, saving significant space during transportation and storage, and facilitating convenient transport. After bolting the sedimentation tank and slurry storage tank on-site, the entire prefabricated mud pit structure can be hoisted and assembled in one go, resulting in extremely fast construction speed. This avoids the problem of repeatedly applying concrete or mortar lining to the foundation pit, as is common with traditional mud pits, improving construction efficiency and effectively shortening the pile foundation construction period.

[0019] 2. Prefabricated mud pits are reusable and have a high reuse rate, reducing material waste. By lifting the sedimentation tank and slurry storage tank separately out of the excavation pit, they can be directly hoisted as a whole for use in the next mud pit, greatly reducing the difficulty of operation. At the same time, the modular design allows the prefabricated mud pits to be disassembled and reused in other projects.

[0020] 3. The prefabricated mud pit steel structure has high rigidity and good stability, which can effectively resist soil pressure and avoid the risk of collapse that may occur due to improper support of traditional on-site plastering mud pits. There is no need to slope the slope and the central partition wall during use, which can effectively save the limited space on the construction site.

[0021] 4. It adopts a factory-assembled structure and special sealing materials, which makes it far superior to mud pits used for on-site plastering. It avoids dust pollution caused by cement and sand mixing and effectively prevents mud from polluting the surrounding environment. It is especially suitable for construction in scenic spots, urban green areas, water source protection areas and other areas with high environmental protection requirements. Attached Figure Description

[0022] Figure 1 This is a three-dimensional structural diagram of a prefabricated mud pit; Figure 2 This is a schematic diagram of the plan structure of a prefabricated mud pit; Figure 3 for Figure 2 A top-view structural diagram; Figure 4 for Figure 2 A schematic diagram of the left-side view structure; Figure 5 This is a three-dimensional structural diagram of a prefabricated slurry storage tank. Figure 6 This is a three-dimensional structural diagram of a prefabricated sedimentation tank. Figure 7 This is a schematic diagram of the corner brace structure; Figure 8 for Figure 7 A top-view structural diagram; Figure 9 This is a schematic diagram showing the connection relationship between the purlin and the side panel; Figure 10 This is a schematic diagram of the connection structure at the connection port; The names corresponding to the serial numbers in the figure are: 1. Prefabricated sedimentation tank; 2. Prefabricated slurry storage tank; 3. Connecting port; 4. Slurry pump bracket; 5. Side plate; 6. Bottom plate; 7. Purlin; 8. Angle brace; 9. Lifting lug; 10. Bolt; 11. Connecting base plate; 12. Channel steel crossbar; 13. Ear plate; 14. Sealing strip; 15. Steel wire mesh filter; 16. Expansion waterstop strip; 17. Pressure strip. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. The described embodiments are only a part of the present invention, and not all of the embodiments.

[0024] Example 1

[0025] The construction of a prefabricated mud pit for drilling mud circulation in bored piles can be completed using the following steps: Step 1: Fabrication and Transportation of Prefabricated Mud Tanks; The prefabricated mud tanks are designed as assembled structures, consisting of prefabricated sedimentation tanks and prefabricated storage tanks. Each component is pre-cut and fabricated on-site, and after surface treatment of the steel structure, it is transported to the site as unit components for installation. Specifically, after the prefabricated mud tank has passed structural design and strength calculations, each component is pre-cut and fabricated on-site. The dimensional accuracy, cutting quality, beveling, and hole position accuracy of each component are checked. Once the requirements are met, pre-assembly is carried out on-site. Pre-assembly ensures the matching of the connection nodes of the prefabricated mud tanks and verifies the overall structural dimensions.

[0026] Step 2: On-site assembly of the prefabricated mud tank; the prefabricated sedimentation tank and prefabricated slurry storage tank are assembled independently. Taking the on-site assembly of the prefabricated sedimentation tank as an example, firstly, the base plate is assembled. The segmented base plates are bolted together, and special sealing materials (such as expansive waterstop strips, rubber waterstops, etc.) are used at the joints between the base plates to ensure a tight connection. Then, each side plate unit is equipped with lifting lug holes. A truck crane is used to lift the side plates one by one into place. Each side plate is bolted to the adjacent base plate and side plate immediately after installation. During the installation of the side plates, diagonal braces or guy ropes can be used for temporary fixation to prevent the side plates from tipping over. Secondly, the internal supports are installed. Corner braces are installed at the four corners of the top beam of the prefabricated sedimentation tank in sequence to form a stable structure. Finally, all bolted connections, plate joints, and other areas where leakage may occur are filled or coated with oil-resistant and corrosion-resistant special sealing materials. The on-site assembly steps for the prefabricated slurry storage tank are the same as those for the prefabricated sedimentation tank, and will not be repeated here.

[0027] Step 3: Water tightness test of the prefabricated mud tank; After the prefabricated sedimentation tank and prefabricated slurry storage tank are assembled on site, a water tightness test should be conducted. Before the test, check the tank structure for obvious cracks and seepage points. During the test, slowly inject water into the sedimentation tank and observe the water level changes and seepage from the tank wall in stages. If there is leakage, mark the location, drain the water, and thoroughly repair the leak.

[0028] Step 4: Excavation and positioning of the mud pit foundation; after site leveling, mark the mud pit dimensions with lime according to the plan. Excavate the foundation pit vertically as much as possible; if the soil is unstable, sloping excavation can be used. After excavating the foundation pit, use a truck crane to lift the prefabricated sedimentation tank and prefabricated slurry storage tank into their designated positions inside the foundation pit, ensuring a tight fit between the two tanks. After hoisting into place, install expansion sealing strips in the connection opening to prevent slurry leakage. Backfill the area around the mud pit with earthwork and set up safety barriers and warning signs around it.

[0029] Step 5: Layout of the mud circulation system; Install the mud pump bracket on the prefabricated mud storage tank, and simultaneously arrange the mud pump and connect the circulation pipeline. Start the mud pump and conduct no-load and load tests to check whether the entire circulation path is unobstructed, whether each piece of equipment is working properly, and whether there are any leaks in the tank walls and interfaces. During drilling, the circulation of mud achieves functions such as wall protection and cuttings carrying.

[0030] Step 6, dismantling the mud pit; after the pile foundation construction is completed, promptly remove the mud and sediment from the prefabricated mud pit, and after being moved away by a crane, steps 4-5 can be repeated for the mud circulation construction of the remaining pier pile foundation bored piles; or it can be dismantled and recycled for the next use.

[0031] The prefabricated sedimentation tank 1 and prefabricated slurry storage tank 2 are bolted together as a single unit. A connecting port 3 is provided at the joint surface of the prefabricated sedimentation tank 1 and prefabricated slurry storage tank 2. Both prefabricated sedimentation tank 1 and prefabricated slurry storage tank 2 include a square frame composed of purlins 7 connected by bolts 10. A base plate 6 and a side plate 5 are respectively installed on the bottom and sides of the square frame via bolts 10 for sealing connection. Sealing strips 14 are laid at the joints of the base plate 6 and the side plate 5. Sealant is applied to the mounting holes of the bolts 10 to prevent leakage. A mud pump bracket 4 is installed on the top of the square frame of the prefabricated slurry storage tank 2. After the prefabricated sedimentation tank and prefabricated slurry storage tank are assembled on-site, a water tightness test should be conducted. Before the test, check the tank structure for obvious cracks and seepage points. During the test, water is slowly injected into the sedimentation tank, and the water level changes and whether there is leakage in the tank wall are observed in stages. If leakage is found, the location is marked, and the area is drained and thoroughly repaired. The assembly of the prefabricated mud pit should be strictly carried out according to the assembly sequence provided in this technology. Forced installation or disassembly is prohibited during assembly to avoid damaging components and affecting reusability. Prefabricated mud pits of different specifications and sizes can be assembled by adjusting the number of square frames, side plates, and bottom plates according to the required mud volume for the on-site pile foundation drilling. The mud carrying rock cuttings back from the bottom of the bored pile passes through the prefabricated sedimentation tank, where inferior, large-particle drill cuttings are initially separated from the circulation system, reducing the burden on subsequent mechanical equipment purification. After initial settling in the prefabricated sedimentation tank, the mud enters the prefabricated storage tank through the connecting port. Various chemical additives, barite, or water are added to the prefabricated storage tank to maintain or adjust key performance indicators such as relative density, viscosity, and sand content of the mud. Qualified mud has a relative density of 1.05–1.2, a viscosity of 16–22s, and a sand content of 4–9%, and is stored in this tank for immediate pumping into the bored pile borehole. After the prefabricated mud pit passes structural design and strength calculations, each component is pre-cut and processed on-site. The dimensional accuracy, cutting quality, beveling, and hole position accuracy of each component are checked, and pre-assembly is carried out on-site once requirements are met. The prefabricated sedimentation tank is the first functional tank into which the mud carrying rock cuttings returned from the bottom of the bored piles enters. Due to the large volume of the prefabricated sedimentation tank, the mud flow rate is significantly reduced. Through its settling function, large, inferior drill cuttings that are detrimental to mud performance are initially separated from the circulation system, reducing the burden on subsequent mechanical purification equipment.

[0032] The square frame is connected to corner braces 8 at its four corners. Each corner brace 8 includes a channel steel crossbar 12 and ear plates 13. The ear plates 13 are fixedly installed at both ends of the channel steel crossbar 12. The channel steel crossbar 12 is connected to the square frame with bolts through the ear plates 13.

[0033] The square frame is symmetrically equipped with lifting lugs 9 at its top. In order to facilitate overall hoisting, lifting lugs 9 are also provided at the bottom of the square frame.

[0034] An expansion sealing strip 16 is affixed to the connection port 3 between the prefabricated sedimentation tank 1 and the prefabricated slurry storage tank 2, and a steel wire mesh 15 is used to seal the connection port 3.

[0035] The steel wire mesh 15 is installed at the connection port 3 by sealing it with pressure strip 17.

[0036] The prefabricated slurry storage tank 2 has a connecting base plate 11 on the top of its square frame. The mud pump bracket 4 is detachably connected to the connecting base plate 11 by bolts. The mud pump bracket 4 consists of three adjustable-angle steel pipes and can support a mud pump to form a mud circulation system.

[0037] The technology of this application has been applied in the drilling mud circulation construction of a bridge bored pile. The dimensions of the prefabricated mud tank are 8m long × 4m wide × 2m high, the dimensions of the prefabricated sedimentation tank and the prefabricated slurry storage tank are 4m long × 4m wide × 2m high, the dimensions of the steel plate unit are 2m × 2m, and the dimensions of the connecting opening are 30cm × 30cm.

[0038] The above description is not intended to limit the present invention, nor is the present invention limited to the above examples. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should be protected by the present invention.

Claims

1. A construction method for a prefabricated mud pit for circulating drilling mud in bored piles, characterized in that, Includes the following steps: Step 1, Prefabricated mud tank processing and transportation; The prefabricated mud tank is divided into prefabricated sedimentation tank and prefabricated slurry storage tank splicing structure design. Each component is pre-cut and processed on site, and after the steel structure surface is treated, it is transported to the site for installation. Step 2: On-site assembly of prefabricated mud pits; the prefabricated sedimentation tank and prefabricated slurry storage tank are assembled independently. Step 3, Prefabricated mud tank water tightness test; After the prefabricated sedimentation tank and prefabricated slurry storage tank are assembled on site, a water tightness test is carried out. Step 4: Excavate and position the foundation of the mud pit; after the site is leveled, excavate the foundation pit; then hoist and connect the prefabricated sedimentation tank and the prefabricated slurry storage tank. Step 5, Mud circulation system layout; Install mud pump brackets on the prefabricated mud storage tank, and arrange the mud pumps and connect the circulation pipelines. Step 6, dismantling the mud pit; after the pile foundation construction is completed, promptly remove the mud and sediment from the prefabricated mud pit, and after being moved away by a crane, steps 4-5 can be repeated for the mud circulation construction of the remaining pier pile foundation bored piles; or it can be dismantled and recycled for the next use.

2. The construction method of the prefabricated mud pit for drilling mud circulation in bored piles according to claim 1, characterized in that, The assembled sedimentation tank (1) and the assembled slurry storage tank (2) are connected together by bolts. The assembled sedimentation tank (1) and the assembled slurry storage tank (2) are provided with a connecting port (3). The assembled sedimentation tank (1) and the assembled slurry storage tank (2) both include a square frame composed of purlins (7) connected by bolts (10). The bottom and sides of the square frame are respectively sealed and connected by bolts (10) to install a bottom plate (6) and a side plate (5). Sealing strips (14) are laid at the installation joints of the bottom plate (6) and the side plate (5). Sealing glue is applied to the installation holes of the bolts (10). A mud pump bracket (4) is installed on the top of the square frame of the assembled slurry storage tank (2).

3. The construction method of the prefabricated mud pit for drilling mud circulation in bored piles according to claim 2, characterized in that, The square frame is connected to corner braces (8) at its four corners. The corner braces (8) include channel steel crossbars (12) and ear plates (13). The ear plates (13) are fixedly installed at both ends of the channel steel crossbars (12). The channel steel crossbars (12) are connected to the square frame with bolts through the ear plates (13).

4. The construction method of the prefabricated mud pit for drilling mud circulation in bored piles according to claim 2 or 3, characterized in that, The square frame is symmetrically provided with lugs (9) at the top.

5. The construction method of the prefabricated mud pit for drilling mud circulation in bored piles according to claim 2, characterized in that, The connection port (3) of the prefabricated sedimentation tank (1) and the prefabricated slurry storage tank (2) is fitted with an expansion sealing strip (16), and the connection port (3) is sealed with a wire mesh (15).

6. The construction method of the prefabricated mud pit for drilling mud circulation in bored piles according to claim 5, characterized in that, The steel wire mesh (15) is installed at the connection port (3) by sealing it with a pressure strip (17).

7. The construction method of the prefabricated mud pit for drilling mud circulation according to claim 2 or 5, characterized in that, The top of the square frame of the prefabricated slurry storage tank (2) is provided with a connecting base plate (11), and the mud pump bracket (4) and the connecting base plate (11) are detachably connected by bolts.

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