Construction method for soft foundation treatment of road in restricted space of river section under high-voltage line

Abstract

The application provides a high-pressure line under a river section limited space road soft foundation treatment construction method, which comprises the following steps: site investigation, hoisting of a cement tank, construction of a protective shed, determination of a high-pressure rotary jet pile machine construction method, determination of a high-pressure rotary jet pile construction parameter, pile site construction lofting, construction of a pressure relief hole, installation of a cement slurry sensing device, construction of a high-strength soil body wall, pile foundation sampling detection, and road inner side pile foundation construction. The application can guarantee the safety of construction operation in a limited operation space, guarantee the pile body quality of the pile foundation in the high-pressure rotary jet pile construction process, reduce the harm of high-pressure electromagnetic radiation to construction personnel, and guarantee that the water source is not polluted.

Description

Technical Field

[0001] This invention relates to the field of soft soil foundation treatment technology for roads in confined spaces, specifically a construction method for soft soil foundation treatment of roads in confined spaces along rivers under high-voltage power lines. Background Technology

[0002] In recent years, the application of widening riverside road sections towards the river has become increasingly common in municipal and highway bridge engineering projects during reconstruction and expansion.

[0003] This invention is based on the Kunshan Outer Ring Road (Zizhu Road-Jinyang Road) renovation project. 1. During the road reconstruction and expansion, a 500KV high-voltage power line could not be relocated due to its location in the soft soil foundation treatment area; the original distance between the ground and the power line was 19-21m. 2. The original design for the soft soil foundation treatment, using cement mixing piles with a pile driver height of 12-24m and supporting cement tank installation height of 9-18m, could not guarantee a 10m safe distance from the high-voltage line. 3. Changing to high-pressure jet grouting piles with a pile driver height of 3-5m met the high-voltage line safety distance requirement, but the supporting equipment, a universal cement tank installation height of 9-18m, could not guarantee a 10m safe distance from the high-voltage line. 4. In the riverside section, the high-pressure jet grouting piles are close to the river with a thin soil layer of only 7-9m. The high-pressure jet grouting construction process involves a minimum grouting pressure of 20Mpa. The soil geological conditions from the outer side of the road to the river consist of 0-3.6m of miscellaneous fill and 3.6-11.2m of silty clay. 5. During the high-pressure jet grouting test pile operation, cement grout breached the soil layer and emitted gas into the river channel under a grouting pressure of 20 MPa, causing water pollution. 6. The loss of cement grout resulted in poor pile formation quality, leading to test pile failure. 7. Analysis of high-pressure jet grouting pile pressure adjustment test data showed that grout and gas emission occurred in the river channel when the soil wall thickness was 7m at a pressure of 18 MPa, 8m at 18.5 MPa, and 9m at 19.5 MPa. No grout and gas emission occurred when the soil wall thickness was 10m and the pressure was 20 MPa, thus meeting the high-pressure jet grouting pile construction process requirements.

[0004] Therefore, ensuring safety during the construction of high-pressure jet grouting piles in thin-walled soil layers along the river under high-pressure lines, guaranteeing the qualified rate of high-pressure jet grouting piles, and ensuring that the construction process does not pollute the river water source have become crucial. Summary of the Invention

[0005] In view of the above-mentioned prior art, the present invention proposes a construction method for soft soil foundation treatment of roads in confined spaces along rivers under high-voltage lines.

[0006] This invention provides a method for treating soft soil foundation in confined spaces along high-voltage power lines near rivers, comprising:

[0007] Step 1: Site survey: Conduct an investigation of the thin-walled soil layer area along the river section of the road under the high-voltage line for soft soil treatment, ensure that the construction safety distance under the high-voltage line is not less than 10m, and select a high-pressure jet grouting pile machine with a body length of 3-5m.

[0008] Step 2, hoisting the cement silo: Use a movable hoisting base to hoist the cement silo;

[0009] Step 3, Construction Protective Shelter: Install an electromagnetic radiation protective shed above the operating platform of the high-pressure jet grouting machine;

[0010] Step 4: Determine the construction method of the high-pressure jet grouting pile machine: When constructing high-pressure jet grouting piles, first construct the outermost row of pile foundations along the road near the river. Perform 180° fan-shaped directional jet grouting from the outside of the road to the inside. The jet grouting pile foundations interlock at a certain distance, and the pile length is greater than the design length. Then construct the cylindrical high-pressure jet grouting piles on the inside of the road.

[0011] Step 5: Determine the construction parameters for high-pressure jet grouting piles;

[0012] Step 6, Pile location layout: Level the site, remove surface debris, and lay out the pile locations according to the road's guide control points and leveling control points. Measure the net distance between the river channel and the outermost pile.

[0013] Step 7: Construct pressure relief holes: Based on the net distance between the river channel and the outermost pile foundation, drill cores for pressure relief holes in the direction perpendicular to the inner road. The distance between the pressure relief holes and the outermost pile foundation shall not be greater than the distance between the river channel and the outermost pile foundation.

[0014] Step 8: Install cement slurry sensing device: Insert cement slurry sensing device into the soil layer next to the river water source. The cement slurry sensing device is connected to the high-pressure jet grouting machine. When the grouting pressure of the high-pressure jet grouting machine breaks through the thin wall soil layer of the river and the cement slurry flows into the river, the cement slurry sensing device is triggered, and the high-pressure jet grouting machine immediately stops grouting.

[0015] Step 9: Construction of high-strength soil wall: The first row of piles is set with a high-pressure jet grouting machine with a 180° swing jetting program. First, the pile foundation construction sequence is set, and the piles are constructed by skipping piles from the direction of the river. After the pile body is solidified, the pile foundations between the piles are interlocked to form a high-strength soil wall.

[0016] Step 10, Pile Foundation Sampling and Testing: Several days after the completion of the first row of piles, a certain depth is excavated at the edge of the pile foundation to check the quality of the pile foundation formation and the interlocking between the piles. Several days after the completion of the first row of piles, core sampling and testing are carried out to confirm the interlocking of the pile foundation and whether the core sampling is qualified.

[0017] Step 11: Construction of pile foundations on the inner side of the road.

[0018] Preferably, in step 2, the cement silo includes a silo body and four columns. The silo body is coated with insulating varnish and has eight retaining rings. Each column is movably connected to the silo body via two retaining rings. The hoisting base has four pre-embedded lifting rings, and the columns are detachably connected to the hoisting base. The silo body is mounted on the hoisting base via the columns. After the height of the silo body is raised by the retaining rings, the cement discharge device below the silo body is assembled.

[0019] Preferably, in step 2, a safety distance linkage device is installed at the top of the tank.

[0020] Preferably, in step 3, the electromagnetic radiation protection shed is constructed by welding four steel pipes to the operating platform, and plastic wire mesh is installed around the top and sides. Electromagnetic radiation protection fabric and electromagnetic interference protection fabric are installed inside the plastic wire mesh to prevent the fabric from being blown onto the high-voltage power lines during strong winds.

[0021] Preferably, in step 5, the first row of 180° fan-shaped directional jet grouting interlocking piles uses a double-pipe design with a pile diameter of 0.8m, a 30cm interlocking between piles, a water-cement ratio of 1.0, a grouting pressure of 20MPa, a jet grouting pipe lifting speed of 0.20-0.25m / min, a rotation speed of 10-12r / min, a pile length greater than the design length by 50cm, a cement content of 350kg / m per meter of pile, and an unconfined compressive strength of not less than 2.5MPa after 28 days.

[0022] The inner side of the road pile foundation adopts double pipe, with a pile diameter of 0.8m, a pile spacing of 1.8m and a quincunx arrangement, a water-cement ratio of 1.0, a grouting pressure of 20-22Mpa, a jet pipe lifting speed of 0.20-0.25m / min, a rotation speed of 20-25r / min, a pile length that meets the design requirements, a cement content of 300kg / m per meter of pile body, and an unconfined compressive strength of not less than 2.5Mpa after 28 days.

[0023] Preferably, in step 7, the pressure relief hole is drilled using drilling equipment to create a hole of the same length as the pile foundation. The pressure relief hole is connected using PVC pipes, and the PVC pipes inside the hole are arranged with perforations to collect cement slurry.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. Due to limited horizontal clearance in the existing environment, this invention replaces the original design of high-pressure jet grouting cylindrical piles with a 180° directional swing jet grouting technique, where the piles interlock. The swing jetting direction towards the inside of the road redirects the grouting pressure inward, reducing the pressure on the thin-walled soil layer in the riverbed. This reinforces the thin-walled soil layer, increasing its resistance to high pressure and forming a high-strength soil wall. Then, the high-pressure jet grouting cylindrical piles are constructed in the construction area inside the road. This ensures that the cement grout in the pile body does not leak or pollute the river water source during construction.

[0026] 2. To further ensure no pollution of river water sources during the high-pressure jet grouting pile construction process of this invention: 1. An intelligent cement slurry sensing device is inserted into the soil layer near the river source. When the high-pressure jet grouting pile's grouting pressure breaks through the thin-walled soil layer of the river and the cement slurry flows into the river, the cement slurry sensing device is triggered, and the pile driver immediately stops grouting. 2. Pressure relief holes are designed on the inner side of the road, with the distance between the pressure relief holes and the first row of piles on the outer side less than or equal to the distance between the first row of piles on the outer side and the riverbank. This directs the high-pressure jet grouting pressure and slurry flow towards the inner side of the road. This dual prevention method prevents cement slurry from polluting the river water source.

[0027] 3. Electromagnetic radiation and interference generated by 500KV high-voltage lines can interfere with electronic equipment used in pile foundations, causing radiation damage to workers. This invention installs an electromagnetic radiation protection canopy above the operating platform of the high-pressure jet grouting pile driver. The canopy is directly installed and fixed to the pile driver, moving synchronously with the machine. The canopy's roof material uses a double-layer insulation system of electromagnetic radiation protection fabric and electromagnetic interference protection fabric to prevent interference from the high-voltage electromagnetic field on electronic equipment and reduce the impact of high-voltage radiation on construction personnel. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall construction process according to an embodiment of the present invention.

[0029] Figure 2 This is a construction diagram of the cement silo in an embodiment of the present invention.

[0030] Figure 3 This is a plan view of the first row of 180° directional swing jet grouting high-pressure jet grouting piles in an embodiment of the present invention.

[0031] Figure 4 This is a schematic diagram of the construction of the cement slurry sensing device in an embodiment of the present invention.

[0032] In the diagram: 1. Lifting base; 2. Tank body; 3. Column; 4. Clamping ring; 5. Lifting ring; 6. Safety distance linkage device. Detailed Implementation

[0033] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific illustrations.

[0034] Example: A construction method for soft soil foundation treatment of roads in confined spaces along rivers under high-voltage power lines, such as... Figure 1-4 As shown, it includes:

[0035] Step 1: Site survey: Conduct an investigation of the thin-walled soil layer area of ​​the soft soil foundation treatment section along the river under the 500kV high voltage line to ensure that the safe construction distance under the high voltage line is not less than 10m, and select a high-pressure jet grouting pile machine with a body length of 4m.

[0036] Step 2, hoisting the cement silo: (Refer to...) Figure 1 , 2 A movable reinforced concrete lifting base 1 is used to lift the cement silo. The cement silo includes a silo body 2 and four columns 3. The silo body 2 is coated with insulating paint. Using an insulated silo body ensures a safe distance from high-voltage lines during installation and prevents the high-voltage lines from conducting electricity in rainy weather. Eight retaining rings 4 are provided on the silo body 2. Each column 3 is movably connected to the silo body 2 through two retaining rings 4. Four lifting rings 5 ​​are pre-embedded on the lifting base 1, and the columns 3 are detachably connected to the lifting base 1. The silo body 2 is installed on the lifting base 1 through the columns 3. After the height of the silo body 2 is raised by the retaining rings 4, the cement discharge device below the silo body 2 is assembled. Compared with the traditional one-piece cement silo, the combined cement silo can reduce the lifting height of the crane during the cement silo installation process and prevent the high-voltage lines from conducting electricity in rainy weather. An intelligent safety distance linkage device 6 is installed at the top of the silo body 2. When the distance between the silo body 2 and the high-voltage line reaches 10m, the height can be automatically lowered to ensure a safe distance. The cement silo must be located close to the high-pressure jet grouting machine. After the cement and water are mixed, they are transported to the pile foundation through a short pipeline to continuously supply cement slurry.

[0037] Step 3, Construction Protective Shelter: An electromagnetic radiation protective shed is installed above the operating platform of the high-pressure jet grouting machine. The electromagnetic radiation protective shed is constructed by welding four steel pipes with a diameter of 5cm to the operating platform. φ3@10x10cm plastic wire mesh is installed on the roof and sides. Electromagnetic radiation protective fabric and electromagnetic interference protective fabric are installed inside the plastic wire mesh to prevent the fabric from being blown onto high-voltage power lines in strong winds.

[0038] Step 4: Determine the construction method of the high-pressure jet grouting pile machine: When constructing high-pressure jet grouting piles, first construct the outermost row of pile foundations along the riverbank. Perform 180° fan-shaped directional jet grouting from the outside of the road to the inside. The jet grouting pile foundations are interlocked at 30cm, and the pile length is 50cm longer than the design length. This measure is to reinforce the thin-walled soil layer of the river channel into a high-strength soil wall, so that the thin-walled soil layer can withstand the high pressure of the high-pressure jet grouting pile. Then construct the cylindrical high-pressure jet grouting piles on the inside of the road.

[0039] Step 5: Determine the construction parameters for high-pressure jet grouting piles: (Refer to...) Figure 3 The first row of 180° fan-shaped directional jet grouting interlocking piles uses double-tube grouting, with a pile diameter of 0.8m, a 30cm interlocking between piles, a water-cement ratio of 1.0, a grouting pressure of 20MPa, a jetting pipe lifting speed of 0.23m / min, a rotation speed of 11r / min, and a pile length greater than the design length by 50cm; the cement usage per meter of pile is 350kg / m, and the 28-day unconfined compressive strength is 2.5MPa; the inner road pile foundation also uses double-tube grouting, with a pile diameter of 0.8m. The piles are arranged in a quincunx pattern with a spacing of 1.8m, a water-cement ratio of 1.0, a grouting pressure of 21MPa, a jet pipe lifting speed of 0.23m / min, a rotation speed of 22r / min, and the pile length meets the design requirements. The cement consumption per meter of the pile is 300kg / m, and the 28-day unconfined compressive strength is 2.5MPa. Cement consumption (Kg / m) = [actual cement consumption (L) / pile length (m)] x specific gravity of cement slurry (Kg / L) x [1 / (1+water-cement ratio)].

[0040] Step 6: Pile location layout: Level the site, remove surface debris, and lay out the pile locations according to the road's guide control points and leveling control points. Measure the net distance between the river channel and the outermost pile foundation.

[0041] Step 7: Construction of Pressure Relief Holes: Based on the net distance between the river channel and the outermost pile foundation, core drilling is performed in the direction perpendicular to the inner road to create pressure relief holes with a diameter of 10cm. The distance between the pressure relief hole and the outermost pile foundation is less than the distance between the river channel and the outermost pile foundation. This ensures that the grouting pressure is released in advance at the pressure relief hole on the inner side of the road before the pressure breaks through the soil layer, preventing cement slurry from polluting the river channel. The pressure relief hole is drilled using drilling equipment to create a hole of the same length as the pile foundation. The pressure relief hole is connected by PVC pipes, and the PVC pipes inside the hole are arranged with perforations to collect the cement slurry. The main function of the pressure relief hole is to prevent the pressure of the high-pressure jet grouting pile from exceeding the limit of the soil layer near the river. The grouting pressure released at the pressure relief hole guides the cement slurry away from the river channel. The principle is that a pressure difference is created between the pressure relief hole and the riverbank, causing the cement slurry to flow towards the inner side of the road where the pressure is lower and is then collected and reused.

[0042] Step 8: Install the cement slurry sensing device: (Refer to...) Figure 1 , 4Intelligent cement slurry sensing devices, 3m long and spaced 5m apart, are inserted into the soil layer near the river source. These devices are connected to a high-pressure jet grouting machine. The installation method is as follows: Step 1: Insert a reusable steel sleeve into the soil layer. The end of the sleeve has an openable drill bit; it is closed at the bottom and opened at the top. Step 2: Insert the cement slurry sensing device into the steel sleeve. Step 3: After installation, remove the steel sleeve. Step 4: Connect the cement slurry sensing device to the high-pressure jet grouting machine. When the grouting pressure of the high-pressure jet grouting machine breaks through the thin-walled soil layer and the cement slurry flows into the river, the cement slurry sensing device is triggered, and the high-pressure jet grouting machine immediately stops grouting.

[0043] Step 9: Constructing a high-strength soil wall: The first row of piles is set with a high-pressure jet grouting machine with a 180° swing jetting program. First, the pile foundation construction sequence is set, and the piles are constructed by skipping piles from the direction of the river. After the pile body is solidified, the pile foundations between the piles are interlocked to form a high-strength soil wall.

[0044] Step 10, Pile Foundation Sampling and Testing: Seven days after the completion of the first row of piles, excavate 1m deep at the edge of the pile foundation to check the quality of the pile foundation formation and the interlocking between the piles. Twenty-eight days after the completion of the first row of piles, core sampling and testing will be carried out to confirm the interlocking of the pile foundation and whether the core sampling is qualified.

[0045] Step 11, Construction of inner road pile foundations: Before constructing the inner road pile foundations, the pressure relief holes are backfilled and sealed to prevent insufficient grouting pressure during the construction process. During the construction of the inner road pile foundations, the pressure changes of the high-pressure jet grouting pile pressure gauge are monitored throughout the process, and the grouting and bubbling near the river are observed to prevent the loss of cement grout from the pile body and pollution of the river water source. During the construction of the first row of inner road pile foundations, the river water source is tested to confirm that the river water source has not been polluted by cement grout. After the pile foundation construction is completed, the integrity, unconfined nature, and cement-soil strength of the high-pressure jet grouting piles are tested for 28 days. After passing the tests, the high-pressure jet grouting piles, cement tanks, and supporting facilities are removed.

[0046] In this embodiment, the vertical clearance for pile foundation construction is limited by 500KV high-voltage power lines, and the soil layer between the river channel outside the road and the construction area is relatively thin (7-9m), further restricting the horizontal clearance for pile foundation construction. This embodiment can ensure the safety of construction operations within a limited working space, guarantee the quality of the pile body during high-pressure jet grouting pile construction, reduce the harm of high-voltage electromagnetic radiation to construction personnel, and protect water sources from pollution.

[0047] This embodiment can solve the problems of safe distance between high-voltage lines and pile drivers during construction, interference and harm to the electronic equipment of pile drivers and construction personnel caused by electronic radiation, and pollution of river cement caused by high pressure grouting during the construction of high-pressure jet grouting piles.

[0048] The above are merely embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent substitutions made using the present invention's specification and drawings, whether directly or indirectly applied to other related technical fields, are similarly within the patent protection scope of the present invention.

Claims

1. A construction method for soft soil foundation treatment in confined spaces along high-voltage power lines near rivers, characterized in that, include: Step 1: Site survey: Conduct an investigation of the thin-walled soil layer area along the river section of the road under the high-voltage line for soft soil treatment, ensure that the construction safety distance under the high-voltage line is not less than 10m, and select a high-pressure jet grouting pile machine with a body length of 3-5m. Step 2, hoisting the cement silo: Use a movable hoisting base to hoist the cement silo; Step 3, Construction Protective Shelter: Install an electromagnetic radiation protective shed above the operating platform of the high-pressure jet grouting machine; Step 4: Determine the construction method of the high-pressure jet grouting pile machine: When constructing high-pressure jet grouting piles, first construct the outermost row of pile foundations along the road near the river. Perform 180° fan-shaped directional jet grouting from the outside of the road to the inside. The jet grouting pile foundations interlock at a certain distance, and the pile length is greater than the design length. Then construct the cylindrical high-pressure jet grouting piles on the inside of the road. Step 5: Determine the construction parameters for high-pressure jet grouting piles; Step 6, Pile location layout: Level the site, remove surface debris, and lay out the pile locations according to the road's guide control points and leveling control points. Measure the net distance between the river channel and the outermost pile. Step 7: Construct pressure relief holes: Based on the net distance between the river channel and the outermost pile foundation, drill cores for pressure relief holes in the direction perpendicular to the inner road. The distance between the pressure relief holes and the outermost pile foundation shall not be greater than the distance between the river channel and the outermost pile foundation. Step 8: Install cement slurry sensing device: Insert cement slurry sensing device into the soil layer next to the river water source. The cement slurry sensing device is connected to the high-pressure jet grouting machine. When the grouting pressure of the high-pressure jet grouting machine breaks through the thin wall soil layer of the river and the cement slurry flows into the river, the cement slurry sensing device is triggered, and the high-pressure jet grouting machine immediately stops grouting. Step 9: Construction of high-strength soil wall: The first row of piles is set with a high-pressure jet grouting machine with a 180° swing jetting program. First, the pile foundation construction sequence is set, and the piles are constructed by skipping piles from the direction of the river. After the pile body is solidified, the pile foundations between the piles are interlocked to form a high-strength soil wall. Step 10, Pile Foundation Sampling and Testing: Several days after the completion of the first row of piles, a certain depth is excavated at the edge of the pile foundation to check the quality of the pile foundation formation and the interlocking between the piles. Several days after the completion of the first row of piles, core sampling and testing are carried out to confirm the interlocking of the pile foundation and whether the core sampling is qualified. Step 11: Construction of pile foundations on the inner side of the road.

2. The construction method for soft soil foundation treatment of roads in confined spaces along rivers under high-voltage power lines as described in claim 1, characterized in that, In step 2, the cement silo includes a silo body and four columns. The silo body is coated with insulating varnish and has eight retaining rings. Each column is movably connected to the silo body via two retaining rings. The hoisting base has four pre-embedded lifting rings, and the columns are detachably connected to the hoisting base. The silo body is mounted on the hoisting base via the columns. After the height of the silo body is raised by the retaining rings, the cement discharge device below the silo body is assembled.

3. The construction method for soft soil foundation treatment of roads in confined spaces along rivers under high-voltage power lines as described in claim 2, characterized in that, In step 2, a safety distance linkage device is installed at the top of the tank.

4. The construction method for soft soil foundation treatment of roads in confined spaces along rivers under high-voltage power lines as described in claim 1 or 2, characterized in that, In step 3, the electromagnetic radiation protection shed is constructed by welding four steel pipes to the operating platform. Plastic wire mesh is installed on the roof and sides. Electromagnetic radiation protection fabric and electromagnetic interference protection fabric are installed inside the plastic wire mesh to prevent the fabric from being blown onto the high-voltage power lines during strong winds.

5. The construction method for soft soil foundation treatment of roads in confined spaces along rivers under high-voltage power lines as described in claim 1 or 2, characterized in that, In step 5, the first row of 180° fan-shaped directional jet grouting interlocking piles: adopts double pipes, pile diameter 0.8m, 30cm interlocking between piles, water-cement ratio 1.0, grouting pressure 20Mpa, jet pipe lifting 0.20-0.25m / min, rotation speed 10-12r / min, pile length greater than design length by 50cm, cement consumption per meter of pile body 350kg / m, and 28-day unconfined compressive strength not less than 2.5Mpa; The inner side of the road pile foundation adopts double pipe, with a pile diameter of 0.8m, a pile spacing of 1.8m and a quincunx arrangement, a water-cement ratio of 1.0, a grouting pressure of 20-22MPa, a jet pipe lifting speed of 0.20-0.25m / min, a rotation speed of 20-25r / min, a pile length that meets the design requirements, a cement content of 300kg / m per meter of pile body, and an unconfined compressive strength of not less than 2.5Mpa after 28 days.

6. The construction method for soft soil foundation treatment of roads in confined spaces along rivers under high-voltage power lines as described in claim 1 or 2, characterized in that, In step 7, the pressure relief hole is drilled using drilling equipment to create a hole of the same length as the pile foundation. The pressure relief hole is connected using PVC pipes, and the PVC pipes inside the hole are arranged with perforations to collect cement slurry.

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