Construction method for utilizing permanent and temporary combination of middle plate as supporting system in underground excavation arch cover method

Abstract

According to the underground excavation arch cover method, the construction method utilizing the permanent and temporary combination of the middle plate and serving as the supporting system adopts an open excavation and underground excavation partition collaborative operation mode, and through the permanent and temporary combination design of the top plate, the middle plate and the bottom plate of internal facilities, the supporting arch cover, the unit top plate, the unit middle plate, the unit bottom plate and other structures serve as temporary supports in the construction stage; the operation stage is directly converted into a permanent structure, dismantling of a temporary support and material waste in a traditional open excavation method are avoided, consumption of building materials such as steel and concrete is remarkably reduced, meanwhile, manpower and time cost of the dismantling procedure is reduced, and comprehensive economic benefits are obviously improved. The method can flexibly adapt to the scene that existing buildings exist around the foundation pit, and the influence on the surface buildings is reduced to the maximum extent through reasonable division of the open excavation area and the underground excavation area.

Description

Technical Field

[0001] This invention relates to the field of foundation pit excavation and internal support construction technology, specifically a construction method using a combination of permanent and temporary intermediate slabs as a support system in the underground excavation arch cover method. Background Technology

[0002] In the field of foundation pit engineering, traditional excavation techniques are mainly divided into two typical methods: open excavation and tunneling, both of which have significant technical limitations. While the open excavation method has a relatively simple construction process, employing a top-down, layered excavation approach and setting up temporary support systems in sections according to the excavation height, the temporary support components are mostly one-time investments. After the main structure is completed, they need to be dismantled, resulting in a significant waste of building materials such as steel and concrete, and the dismantling process adds extra construction time and labor costs. Although tunneling is unaffected by buildings above the foundation pit, it faces more complex technical challenges. Limited by underground working space, soil transportation efficiency is low during tunneling, and traditional transportation equipment struggles to operate efficiently in confined spaces, leading to difficulties in soil removal and extended construction periods. How to solve the problems of support costs and soil transportation during foundation pit excavation is an urgent issue to be addressed. Summary of the Invention

[0003] The purpose of this invention is to provide a construction method for the cut-and-cover arch method that utilizes a combination of permanent and temporary middle plates as a support system. This method combines open and cut excavation, and uses permanent internal structures to replace temporary supports. It also employs hydraulic flushing and mud suction to overcome the difficulties of soil excavation and transportation, thus solving the problems in the prior art.

[0004] The technical solution adopted by this invention to solve its technical problem is: the underground excavation arch cover method, which utilizes a combination of permanent and temporary slabs as a support system, includes the following steps: ① Selecting the area to be excavated in the foundation pit and constructing a diaphragm wall around the perimeter of the foundation pit; ② After the diaphragm wall in step ① is completed, several open-cut and underground excavation areas are demarcated within the foundation pit according to the actual surface building conditions, and a supporting arch cover is constructed in all underground excavation areas as the supporting structure for the top of the underground excavation area and part of the roof structure for the facilities within the foundation pit; ③ After the supporting arch cover in step ② is completed, excavation machinery is used to excavate downwards in all open-cut areas. When the excavation reaches the depth of the supporting arch cover in the adjacent underground excavation area, the excavation is stopped, and the excavation surface is leveled. ④ After the unit top slabs in step ③ are constructed, excavation continues downward to the height of the middle slab of the internal facility. Excavation is stopped, the excavation surface is leveled, and a portion of the first unit middle slab of the internal facility is constructed on the soil. The first unit middle slab is fixedly connected to the diaphragm walls on both sides to form a support. The area of ​​the first unit middle slab is smaller than the area of ​​the open excavation area. ⑤ After the first unit middle slab in step ④ is constructed, excavation continues downward to the height of the bottom slab of the internal facility. Excavation is stopped, the excavation surface is leveled, and a portion of the first unit bottom slab of the internal facility is constructed on the soil. The first unit base plate is fixedly connected to the underground continuous walls on both sides to form a support; ⑥ After the first unit base plate is constructed in step ⑤, a sedimentation tank is placed on the soil surface above the supporting arch in each excavation area; ⑦ After the sedimentation tank is placed in step ⑥, the bottom soil of the supporting arch in all excavation areas is hydraulically flushed and excavated, and a mud pump is placed at the position after hydraulic flushing to pump and transport the mixed mud to the sedimentation tank. After the soil at the bottom of the supporting arch is excavated to the height of the first unit middle plate, the hydraulic flushing is stopped, the excavation surface is leveled, and the second unit middle plate of the internal facilities is constructed on the soil in the excavation area, so that the second unit middle plate is fixedly connected to the underground continuous walls on both sides to form a support; ⑧ After the second unit middle plate is constructed in step ⑦, the downward hydraulic flushing continues. The scouring excavation refers to the process of stopping the hydraulic scouring at the height of the first unit's bottom slab, leveling the excavation surface, and then constructing a portion of the second unit's bottom slab for the internal facilities on the soil in the cut-and-cover area. The second unit's bottom slab is then fixedly connected to the underground continuous walls on both sides to form a support. ⑨ After the second unit's bottom slab is constructed in step ⑧, a bottom slab connecting plate is constructed between the second unit's bottom slab in the cut-and-cover area and the first unit's bottom slab in the adjacent open-cut area to form a complete bottom slab structure for the internal facilities. A middle plate connecting plate is constructed between the second unit's middle slab in the cut-and-cover area and the first unit's middle slab in the adjacent open-cut area to form a complete middle slab structure for the internal facilities. A top plate connecting plate is constructed between the supporting arch in the cut-and-cover area and the unit's top slab in the adjacent open-cut area to form a complete top slab structure for the internal facilities.⑩ After the bottom slab, middle slab, and top slab structures of the internal facilities in step ⑨ are constructed, the soil above the top slab of the unit in the open-cut area is backfilled, the backfilled soil is leveled, and the road surface above the foundation pit is restored, completing the construction. In step ⑦, after the slurry is pumped and transported to the sedimentation tank, it is left to stand for a set time to allow the soil inside to settle to the bottom. The clarified water at the top is then recycled using a water pump and reused as a water source for hydraulic flushing. The settled soil at the bottom is transferred to a transport vehicle using a grab bucket and removed. After drying, it is used as backfill soil in step ⑩. When constructing the second unit middle slab in step ⑦ and the second unit bottom slab in step ⑧, molds are constructed on the surface of the soil. Reinforcing bars are tied and concrete is poured inside the molds to create the required middle and bottom slab structures. After construction, the soil under the molds is flushed using hydraulic flushing, and the molds are separated from the middle and bottom slab structures. The molds include a concrete substrate, the inner surface of which is coated with a putty layer. The mold includes a base composed of plywood layers, with a linoleum layer on the inner surface of the plywood layers. A sand layer and a soil-rock layer are also provided between the plywood layers and the bottom soil. The mold also includes a concrete base, with a plywood layer on the inner surface of the concrete base. During the construction of the supporting arch in step ②, the unit top plate in step ③, the first unit middle plate in step ④, the first unit bottom plate in step ⑤, the second unit middle plate in step ⑦, and the second unit bottom plate in step ⑧, waterproofing is carried out between the mold and the continuous underground walls on both sides. The sedimentation tank used in step ⑥ includes a sedimentation tank body. A ring frame is detachably installed around the lower part of the sedimentation tank body via bolts. A hand-cranked jack is installed at each of the four corners of the ring frame, with the shell of the hand-cranked jack fixed to the ring frame. Lockable universal rollers are installed at the bottom of the telescopic rod of the hand-cranked jack. The device used for hydraulic scouring of the soil in step ⑦ includes a traveling vehicle with a placement seat. The top of the placement seat is equipped with a horizontally arranged first slewing bearing. A vertically arranged second slewing bearing is installed on the slewing seat of the first slewing bearing. A clamping seat is installed on the slewing seat of the second slewing bearing. A water spray pipe is installed in the clamping seat. The clamping seat is equipped with a locking bolt. Rotating the locking bolt can lock the water spray pipe in the clamping seat. A connected water supply pipe is installed on the water spray pipe. A rotatable chisel frame is also provided on the outer periphery of the water spray pipe near the drain outlet. The chisel frame is equipped with circumferentially arranged chisel rods, each of which extends outward from the drain outlet along the length of the water spray pipe. A drive motor is installed on the water spray pipe, and a drive gear is installed on the output shaft of the drive motor. The end of the chisel frame is provided with a gear ring that meshes with the drive gear. When the drive motor starts, it can cause the chisel frame to rotate relative to the water spray pipe. An annular guide groove is also formed on the outer circumference of the water spray pipe, and several sliders that cooperate with the annular guide groove are provided inside the chisel frame.

[0005] The positive effects of this invention are as follows: The construction method of the cut-and-cover arch method described in this invention utilizes a combination of temporary and permanent middle slabs as a support system. It adopts a zoned collaborative operation mode of open and cut excavation. Through the design of the permanent and temporary combination of the top, middle, and bottom slabs of the internal facilities, the supporting arch, unit top slab, unit middle slab, and unit bottom slab serve as temporary supports during the construction phase and are directly transformed into permanent structures during the operation phase. This avoids the removal of temporary supports and material waste in traditional open-cut methods, significantly reducing the consumption of building materials such as steel and concrete. It also reduces the labor and time costs of demolition procedures, resulting in a significant improvement in overall economic benefits. This method can flexibly adapt to scenarios where there are existing buildings around the excavation pit. Through the reasonable division of open and cut excavation areas, it minimizes the impact on surface buildings.

[0006] By combining hydraulic flushing excavation technology within the underground excavation area and pumping the mixed mud into a sedimentation tank using a mud pump, the problem of difficult soil transportation in the underground excavation method was solved, the efficiency bottleneck of traditional mechanical soil removal was avoided, the soil excavation speed in the underground excavation area was significantly improved, and the overall construction period was effectively shortened.

[0007] The diaphragm wall and the multi-layered slab structure (top slab, middle slab, and bottom slab) form a composite support system. By constructing unit slabs in stages and fixing them to the diaphragm wall, the lateral earth pressure of the excavation pit is effectively dispersed, reducing the risk of structural deformation. Especially in geologically complex areas, the synergistic effect of the supporting arch and the middle slab significantly improves the structural stability of the excavated area. Attached Figure Description

[0008] Figure 1 This is a simplified schematic diagram showing the completion of step ① in this invention; Figure 2 This is a simplified schematic diagram showing the completion of step ② in this invention; Figure 3 This is a simplified schematic diagram showing the completion of step ③ in this invention; Figure 4 This is a simplified schematic diagram showing the completion of step ④ in this invention; Figure 5 This is a simplified schematic diagram showing the completion of step ⑤ in this invention; Figure 6 This is a simplified schematic diagram showing the completion of step ⑥ in this invention; Figure 7 This is a simplified schematic diagram showing the completion of step ⑦ in this invention; Figure 8 This is a simplified schematic diagram showing the completion of step ⑧ in this invention; Figure 9 This is a simplified schematic diagram showing the result after step 9 of this invention is completed; Figure 10 This is a simplified schematic diagram showing the completion of step 10 in this invention; Figure 11 This is a schematic diagram of the external shape of the mold in this invention; Figure 12 This is a cross-sectional schematic diagram of the components of the first mold embodiment; Figure 13 This is a cross-sectional schematic diagram of the components of the second mold embodiment; Figure 14 This is a cross-sectional schematic diagram of the components of the third mold embodiment; Figure 15This is a schematic diagram showing the state of the second unit plate constructed using a mold in step ⑦. Figure 16 This is a schematic diagram of the sedimentation tank. Figure 17 This is a schematic diagram of the device used to hydraulically flush the soil in step ⑦. Figure 18 yes Figure 17 An enlarged view of the sectional view along the AA direction; Figure 19 yes Figure 17 An enlarged view of the BB-axis sectional view; Figure 20 yes Figure 17 An enlarged view of the sectional view along the CC direction; Figure 21 This is a schematic diagram showing the usage state of the chisel frame extending into the soil for hydraulic scouring. Detailed Implementation

[0009] The present invention describes a construction method for a cut-and-cover arched structure that utilizes a combination of permanent and temporary intermediate slabs as a support system. Figure 1-10 As shown, it includes the following steps: ① Select the area to be excavated in the foundation pit and construct a diaphragm wall 1 around the perimeter of the pit; ② After the diaphragm wall 1 is completed in step ①, delineate several open-cut and tunnel areas within the foundation pit according to the actual surface building conditions, and construct supporting arches 2 in all tunnel areas as the supporting structure for the top of the tunnel area and part of the roof structure for the facilities within the foundation pit; ③ After the supporting arches 2 are completed in step ②, use excavating machinery to excavate downwards in all open-cut areas. When the excavation reaches the depth of the supporting arches 2 in the adjacent tunnel area, stop the excavation, level the excavation surface, and construct partial unit roof slabs 3 for the internal facilities on the soil. The unit roof slabs 3 are fixedly connected to the diaphragm walls 1 on both sides to form a support, wherein the area of ​​the unit roof slab 3 is smaller than the area of ​​the open-cut area at that location. ④ After the top plate 3 of the unit in step ③ is constructed, continue excavating downwards to the height of the middle plate of the internal facility, stop excavating, level the excavation surface, and construct part of the first unit middle plate 4 of the internal facility on the soil, so that the first unit middle plate 4 is fixedly connected to the underground continuous walls 1 on both sides to form a support, wherein the area of ​​the first unit middle plate 4 is smaller than the area of ​​the open excavation area; ⑤ After the first unit middle plate 4 of step ④ is constructed, continue excavating downwards to the height of the bottom plate of the internal facility, stop excavating, level the excavation surface, and construct part of the first unit bottom plate 5 of the internal facility on the soil, so that the first unit bottom plate 5 is fixedly connected to the underground continuous walls 1 on both sides to form a support; ⑥ After the first unit bottom plate 5 of step ⑤ is constructed, place sedimentation tanks 6 on the soil surface above the supporting arch 2 in each underground excavation area; ⑦ After the sedimentation tank 6 in step ⑥ is placed, hydraulic scouring excavation is carried out on the bottom soil of the supporting arch 2 in all underground excavation areas. A mud pump 7 is placed at the location after hydraulic scouring to pump the mixed mud into the sedimentation tank 6. After the soil at the bottom of the supporting arch 2 is excavated to the height of the first unit middle plate 4, hydraulic scouring is stopped. After leveling the excavation surface, a portion of the second unit middle plate 8 for the internal facilities is constructed on the soil in the underground excavation area, allowing the second unit middle plate 8 to be fixedly connected to the underground continuous walls 1 on both sides to form a support. ⑧ After the second unit middle plate 8 in step ⑦ is constructed, hydraulic scouring excavation continues downward to the height of the first unit bottom plate 5. Hydraulic scouring is stopped, and after leveling the excavation surface, a portion of the second unit bottom plate 9 for the internal facilities is constructed on the soil in the underground excavation area, allowing the second unit bottom plate 9 to be fixedly connected to the underground continuous walls 1 on both sides to form a support. Continuous wall 1 is fixedly connected to form a support; ⑨ After the second unit bottom plate 9 in step ⑧ is constructed, a bottom plate connecting plate 10 is constructed between the second unit bottom plate 9 in the cut-and-cover area and the first unit bottom plate 5 in the adjacent open-cut area to form a complete bottom plate structure for the internal facilities; a middle plate connecting plate 11 is constructed between the second unit middle plate 8 in the cut-and-cover area and the first unit middle plate 4 in the adjacent open-cut area to form a complete middle plate structure for the internal facilities; a top plate connecting plate 12 is constructed between the supporting arch 2 in the cut-and-cover area and the unit top plate 3 in the adjacent open-cut area to form a complete top plate structure for the internal facilities; ⑩ After the bottom plate structure, middle plate structure and top plate structure of the internal facilities in step ⑨ are constructed, the soil above the unit top plate 3 in the open-cut area is backfilled, the backfilled soil is leveled and the road surface on the foundation pit is restored, and the construction is completed.

[0010] During the preliminary preparation and initial construction of the foundation pit in step ①, the area to be excavated is selected, and the foundation pit boundary is precisely planned based on the geological survey report and surrounding environmental conditions. Then, a diaphragm wall 1 is constructed around the perimeter of the foundation pit. The diaphragm wall 1 can be a reinforced concrete structure, and its thickness and depth are determined comprehensively based on factors such as the depth of the foundation pit, geological conditions, and the load-bearing capacity of surrounding buildings. During construction, the verticality and quality of the diaphragm wall 1 are strictly controlled to ensure it can effectively block soil and water from outside the foundation pit, providing stable boundary conditions for subsequent construction.

[0011] When dividing the open and cut excavation areas and constructing the supporting arch in step ②, several open and cut excavation areas should be designated at intervals according to the actual surface building conditions. Areas with dense surface buildings and high settlement requirements should be designated as cut excavation areas; while areas with relatively open surfaces and fewer buildings can be designated as open excavation areas. Supporting arches 2 are constructed in all cut excavation areas. These arches are made of reinforced concrete and are arched in shape, fully utilizing the stress characteristics of the arch structure to effectively transfer the pressure of the upper soil to the diaphragm walls 1 on both sides. The supporting arches 2 serve as the top support structure of the cut excavation area, and their small bending angle also allows them to function as part of the roof structure of facilities within the excavation pit, realizing a design concept that combines permanent and temporary structures.

[0012] During step ③, when performing layered excavation of the open-cut area and constructing the unit top slab 3, close attention must be paid to the deformation of the diaphragm wall 1 during the excavation process. If any abnormalities are found, reinforcement measures should be taken promptly. The unit top slab 3 can be a reinforced concrete structure, and its thickness is determined based on the superstructure load and design requirements. The area of ​​the unit top slab 3 is smaller than the area of ​​the open-cut area to allow necessary operating space for subsequent excavation and construction.

[0013] When the open-cut area is further excavated and the first unit middle plate 4 is constructed in step ④, the first unit middle plate 4 can also be made of reinforced concrete. Similar to the unit top plate 3, it is fixedly connected to the underground continuous walls 1 on both sides to form a support. The area of ​​the first unit middle plate 4 is smaller than the area of ​​the open-cut area, leaving the necessary operating space for subsequent excavation and construction. At the same time, the construction of the first unit middle plate 4 further enhances the stability of the foundation pit and provides an intermediate support platform for subsequent construction.

[0014] In step ⑤, during the final excavation of the open-cut area and the construction of the first unit base slab 5, since the first unit base slab 5 serves as the foundation structure for the facilities inside the foundation pit, its quality directly affects the stability of the entire building. Therefore, the quality of concrete pouring and curing conditions must be strictly controlled during the construction process.

[0015] During the placement of sedimentation tanks in the underground excavation area in step ⑥, since the top of the underground excavation area has not been excavated, an area with fewer surface buildings can be selected as the placement area for sedimentation tank 6, serving as the construction site on the ground. This allows for the pumping of mud without affecting existing buildings. The size, capacity, and number of sedimentation tanks 6 can be determined based on the amount of soil excavated and the amount of mud generated in the underground excavation area. Their material can be reinforced concrete or steel plates, ensuring that the sedimentation tanks 6 have sufficient strength and stability to withstand the weight and pressure of the mud.

[0016] During step ⑦, when hydraulic scouring excavation of the cut-and-cover area and construction of the second unit slab 8 are carried out, high-pressure water jets are used for hydraulic scouring. The high-pressure water flow washes the soil into a slurry. A mud pump 7 is placed at the location after hydraulic scouring to pump the mixed slurry into a sedimentation tank 6, thereby improving the efficiency of soil excavation in the cut-and-cover area. The height of the second unit slab 8 is adapted to the height of the first unit slab 4 in the open-cut area, and together they can form the slab structure system for subsequent internal facilities.

[0017] When continuing hydraulic scouring excavation and constructing the second unit base plate 9 in step ⑧, similar to step ⑦, it can improve the efficiency of soil excavation in the underground excavation area, and the second unit base plate 9 and the first unit base plate 5, which are adapted to the height position, can jointly form the base plate structure system in the subsequent internal facilities.

[0018] When constructing the connection structure of the top slab, middle slab, and bottom slab between the open-cut and cut-and-cover areas in step 9, it is necessary to ensure the connection strength and performance of the connection parts, ensure that the concrete is poured densely, so that the entire internal facility forms an organic whole and improves the integrity and stability of the structure.

[0019] In step ⑩, during soil backfilling and road restoration, since the soil above the mined area is not excavated, only the soil above unit top slab 3 in the open-cut area needs to be backfilled. This effectively improves construction efficiency and shortens the backfilling construction cycle. During backfilling, layered backfilling and compaction are required to ensure the density of the backfill soil meets design requirements. The backfilled soil is leveled, and the road surface above the foundation pit is restored to ensure that the road surface smoothness, slope, and other indicators meet traffic and usage requirements, thus completing the construction.

[0020] Through the detailed construction steps described above, the underground excavation arch cover method of this invention utilizes a combination of permanent and temporary middle plates as a support system. It adopts the permanent structure of the internal facilities as temporary support, eliminating the need for subsequent dismantling operations of traditional temporary supports. At the same time, the use of hydraulic flushing excavation in the underground excavation area effectively solves the problems of support costs and soil transportation during the foundation pit excavation process, improves construction efficiency, reduces project costs, and has significant economic and social benefits.

[0021] Furthermore, to achieve efficient treatment of the pumped-out mud, after the mud is pumped and transported to the sedimentation tank 6 in step ⑦, it is left to stand for a set time to allow the soil inside to settle to the bottom of the tank. The clarified water at the top is then recycled using a water pump and reused as a water source for hydraulic flushing. The settled soil at the bottom is transferred to a transport vehicle using a grab bucket and removed. After drying, it is used as backfill soil in step ⑩. The placement of the sedimentation tank 6 does not affect the normal construction operations within the foundation pit. After settling, the mud can be separated, the clarified water at the top can be recycled and reused, and the settled soil at the bottom can be directly used for backfilling in the open excavation area after drying. This reduces the amount of earthwork transported and dust pollution. Hydraulic flushing, instead of mechanical excavation, not only improves excavation efficiency but is also not limited by construction space, effectively reducing construction noise and mechanical emissions, and meeting green construction standards.

[0022] Furthermore, in step ⑦, when constructing the second unit middle plate 8, and in step ⑧, when constructing the second unit bottom plate 9, a mold 13 is constructed on the surface of the soil. Reinforcing bars are tied and concrete is poured within the mold 13 to construct the required middle and bottom plate structures. After construction, the soil beneath the mold 13 is flushed with water, separating the mold 13 from the middle and bottom plate structures. The mold 13 enhances the strength and quality of the middle and bottom plate structures. After excavating to a certain depth, the unexcavated soil is used as support. Compared to the traditional method of using scaffolding for support after excavation, this effectively reduces the construction steps for the structural slabs, saves on scaffolding usage and material turnover costs during construction, and lowers construction costs.

[0023] like Figure 12 As shown, the mold 13 includes a concrete substrate 14, and a putty layer 15 is coated on the inner surface of the concrete substrate 14. The putty layer 15 can make the concrete surface smoother and more even, improve the quality of the outer periphery of the middle plate and bottom plate structure, and facilitate the subsequent demolding operation.

[0024] like Figure 13 As shown, the mold 13 may further include a base composed of a plywood layer 16, with a linoleum layer 17 on the inner surface of the plywood layer 16. A sand layer 18 and a soil-rock layer 19 are also provided between the plywood layer 16 and the bottom soil. The linoleum layer 17 facilitates demolding of the constructed structure, while the sand layer 18 and the soil-rock layer 19 act as a buffer and leveling layer, making the mold 13 more stable when placed on undisturbed soil.

[0025] like Figure 14 As shown, the mold 13 may include a concrete substrate 14, and a plywood layer 16 is provided on the inner surface of the concrete substrate 14. This structure combines the advantages of concrete and plywood, and has both a certain strength and is easy to demold.

[0026] Furthermore, during the construction of the supporting arch 2 in step ②, the unit top slab 3 in step ③, the first unit middle slab 4 in step ④, the first unit bottom slab 5 in step ⑤, the second unit middle slab 8 in step ⑦, and the second unit bottom slab 9 in step ⑧, waterproofing construction is carried out between these structures and the diaphragm walls 1 on both sides. Waterproofing construction can be achieved by applying waterproof coatings or laying waterproof membranes to ensure that there is no leakage at the connection points between structures, thus guaranteeing the normal use and durability of the internal facilities.

[0027] Furthermore, in order to allow the sedimentation tank 6 located at the top of the excavated area to adapt its position to the water erosion, and to be able to pass over low protruding structures on the road surface, such as curbs and low obstacles, etc., Figure 16 As shown, the sedimentation tank 6 used in step ⑥ includes a sedimentation tank body 20. A ring frame 21 is detachably installed around the lower part of the sedimentation tank body 20 by bolts. A hand-cranked spanner 22 is installed at each of the four corners of the ring frame 21. The shell of the hand-cranked spanner 22 is fixed on the ring frame 21. Lockable universal rollers 23 are installed at the bottom of the telescopic rod of the hand-cranked spanner 22.

[0028] The height of the sedimentation tank 20 above the ground can be adjusted by manually cranking the top 22, thus enabling normal crossing of low protruding structures. At the same time, the universal rollers 23 facilitate the overall sedimentation tank 6 to be moved in a specific direction, ensuring that it can be adapted to the hydraulic flushing and mud suction at the bottom of the underground excavation area.

[0029] The aforementioned device boasts advantages such as flexible position adjustment, convenient and time-saving relocation, stable and reliable structure, and convenient and quick maintenance and replacement. The combination of the hand-cranked jack 22 and the universal casters 23 allows it to move with the water flow, easily overcoming low obstacles and adapting to different working conditions. The universal casters 23 eliminate the need for large equipment when moving the sedimentation tank 6; manual pushing is sufficient, saving manpower and time and reducing safety hazards. The ring frame 21 enhances the structural stability of the sedimentation tank 6, and the universal casters 23 can be locked to prevent accidental movement, ensuring construction safety. All components are detachable, facilitating disassembly and replacement in case of malfunction, shortening maintenance time, reducing costs, and extending service life.

[0030] Furthermore, in order to achieve smooth scouring of the soil in the excavation area, such as Figure 17-21As shown, the device used for hydraulic scouring of the soil in step ⑦ includes a traveling vehicle 24, on which a placement seat 25 is mounted. A horizontally arranged first slewing bearing 26 is provided on the top of the placement seat 25. A vertically arranged second slewing bearing 27 is mounted on the slewing seat of the first slewing bearing 26. A clamping seat 28 is mounted on the slewing seat of the second slewing bearing 27, and a water spray pipe 29 is fitted inside the clamping seat 28. The traveling vehicle 24 can move the water spray pipe 29 to the designated scouring position. The arrangement of the two slewing bearings allows the water spray pipe 29 to be adjusted in both horizontal and vertical directions to align with all scouring and excavation positions of the soil.

[0031] To facilitate the extension and retraction of the water spray pipe 29 relative to the clamping seat 28 in the length direction, the clamping seat 28 is provided with a locking bolt 30. Rotating the locking bolt 30 can lock the water spray pipe 29 inside the clamping seat 28, and loosening the locking bolt 30 can adjust the length of the water spray pipe 29 extending out of the clamping seat 28. A connected water supply pipe 31 is installed on the water spray pipe 29, and the water supply pipe 31 is connected to a water source to provide the necessary rinsing water.

[0032] When flushing soil in the excavated area, if a dense soil-rock mixture is encountered, it is difficult to excavate the soil around large-diameter stones using only water flushing. To accommodate excavation of different types of soil, a rotating chisel frame 32 is installed around the water pipe 29 near the drainage outlet. The chisel frame 32 is equipped with circumferentially arranged chisel rods 33, each extending outward from the drainage outlet along the length of the water pipe 29. The chisel rods 33 on the chisel frame 32 can move to contact the soil surface and, through their rotation, break and excavate harder stones in the soil to facilitate subsequent water flushing. The installation of the chisel frame 32 does not affect the normal water output and flushing of the water pipe 29.

[0033] To drive the rotation of the chisel frame 32, a drive motor 34 is mounted on the water spray pipe 29. A drive gear 35 is mounted on the output shaft of the drive motor 34. The end of the chisel frame 32 is provided with a gear ring 36 that meshes with the drive gear 35. When the drive motor 34 is started, it can drive the chisel frame 32 to rotate relative to the water spray pipe 29. To guide the rotation of the chisel frame 32, an annular guide groove 38 is also provided on the outer periphery of the water spray pipe 29. Several sliders 37 that cooperate with the annular guide groove 38 are provided inside the chisel frame 32.

[0034] The aforementioned soil flushing device boasts advantages such as precise flushing location, flexible water pipe length adjustment, adaptability to various soil types, non-interference between chiseling and flushing, and stable and reliable chiseling frame rotation. The traveling trolley 24, coupled with double slewing bearings, allows the water pipe 29 to rotate flexibly and precisely align with various flushing positions on the soil, enhancing the flushing effect. Locking bolts 30 allow for length adjustment of the water pipe 29, adapting to different flushing needs, improving versatility, and reducing equipment costs. The chiseling frame 32 and chisel rod 33 can break hard rocks, creating conditions for hydraulic flushing, adapting to different soil types, and improving excavation efficiency. The design of the chiseling frame 32 does not interfere with the water flow from the water pipe 29; both operate synchronously, improving construction efficiency and shortening the cycle time. The transmission system provides stable power, and the annular guide groove 38 and slider 37 guide the chiseling frame 32, ensuring that its rotation does not deviate or jam.

[0035] The technical solutions of this invention are not limited to the embodiments described herein. All technical contents not described in detail herein are well-known technologies.

Claims

1. A construction method for a cut-and-cover arched structure utilizing a combination of permanent and temporary intermediate slabs as a support system, characterized in that: It includes the following steps: ① Select the area to be excavated in the foundation pit and construct a diaphragm wall around the perimeter of the foundation pit (1). ②After the underground continuous wall (1) in step ① is completed, several open-cut and tunnel areas are delineated in the foundation pit according to the actual surface building conditions, and supporting arches (2) are constructed in all tunnel areas as supporting structures for the top of the tunnel areas and part of the top plate structure of the facilities in the foundation pit. ③ After the supporting arch (2) in step ② is completed, use excavation machinery to excavate downwards in all open excavation areas. When the excavation reaches the depth of the supporting arch (2) in the adjacent underground excavation area, stop the excavation, level the excavation surface, and construct a partial unit top plate (3) of the internal facilities on the soil. Let the unit top plate (3) be fixedly connected to the underground continuous walls (1) on both sides to form a support. The area of ​​the unit top plate (3) is smaller than the area of ​​the open excavation area. ④ After the unit top plate (3) in step ③ is constructed, continue to excavate downwards to the height of the middle plate of the internal facility, stop excavation, level the excavation surface, and construct part of the first unit middle plate (4) of the internal facility on the soil. Let the first unit middle plate (4) be fixedly connected to the underground continuous walls (1) on both sides to form a support. The area of ​​the first unit middle plate (4) is smaller than the area of ​​the open excavation area. ⑤ After the first unit plate (4) in step ④ is constructed, continue to excavate downwards to the height of the bottom plate of the internal facility, stop excavating, level the excavation surface, and construct part of the first unit bottom plate (5) of the internal facility on the soil, so that the first unit bottom plate (5) is fixedly connected to the underground continuous walls (1) on both sides to form a support. ⑥ After the first unit base plate (5) in step ⑤ is constructed, a sedimentation tank (6) is placed on the soil surface above the support arch (2) in each underground excavation area. ⑦ After the sedimentation tank (6) in step ⑥ is placed, hydraulic flushing is carried out on the bottom soil of the supporting arch (2) in all underground excavation areas, and a mud pump (7) is placed at the position after hydraulic flushing to pump and transport the mixed mud into the sedimentation tank (6). After the soil at the bottom of the supporting arch (2) is excavated to the height of the first unit middle plate (4), hydraulic flushing is stopped, the excavation surface is leveled, and the second unit middle plate (8) of the internal facilities is constructed on the soil of the underground excavation area. The second unit middle plate (8) is fixedly connected to the underground continuous walls (1) on both sides to form a support. ⑧ After the second unit plate (8) in step ⑦ is constructed, continue to excavate downwards by hydraulic flushing to the height of the first unit bottom plate (5), stop hydraulic flushing, level the excavation surface, and then construct part of the second unit bottom plate (9) of the internal facilities on the soil in the underground excavation area, so that the second unit bottom plate (9) is fixedly connected to the underground continuous walls (1) on both sides to form a support. ⑨ After the second unit base plate (9) in step ⑧ is constructed, a base plate connecting plate (10) is constructed between the second unit base plate (9) in the underground excavation area and the first unit base plate (5) in the adjacent open excavation area to form a complete base plate structure for the internal facilities; a middle plate connecting plate (11) is constructed between the second unit middle plate (8) in the underground excavation area and the first unit middle plate (4) in the adjacent open excavation area to form a complete middle plate structure for the internal facilities; a top plate connecting plate (12) is constructed between the supporting arch (2) in the underground excavation area and the unit top plate (3) in the adjacent open excavation area to form a complete top plate structure for the internal facilities; ⑩ After the bottom plate structure, middle plate structure and top plate structure of the internal facilities in step ⑨ are completed, backfill the soil above the unit top plate (3) in the open excavation area, level the backfilled soil and restore the road surface on the foundation pit, and the construction is completed.

2. The construction method of the cut-and-cover arch method according to claim 1, which utilizes a combination of permanent and temporary intermediate slabs as a support system, is characterized in that: In step ⑦, after the mud is pumped and transported to the sedimentation tank (6), it is left to stand for a set time to allow the soil inside to settle to the bottom of the tank. The water is then pumped to reclaim the clear water from the top and reused as a water source for hydraulic flushing. The settled soil at the bottom is transferred to a transport vehicle using a grab bucket and then dried before being used as backfill soil in step ⑩.

3. The construction method of the cut-and-cover arch method according to claim 1, which utilizes a combination of permanent and temporary intermediate slabs as a support system, is characterized in that: When making the second unit middle plate (8) in step ⑦ and the second unit bottom plate (9) in step ⑧, a mold (13) is constructed on the surface of the soil, and steel bars are tied and concrete is poured in the mold (13) to make the required middle plate and bottom plate structure. After the construction is completed, the soil under the mold (13) is flushed with water and the mold (13) is separated from the middle plate and bottom plate structure.

4. The construction method of the cut-and-cover arch method according to claim 3, which utilizes a combination of permanent and temporary intermediate slabs as a support system, is characterized in that: The mold (13) includes a concrete substrate (14), and the inner surface of the concrete substrate (14) is coated with a putty layer (15).

5. The construction method of the cut-and-cover arch method according to claim 3, which utilizes a combination of permanent and temporary intermediate slabs as a support system, is characterized in that: The mold (13) includes a base composed of a plywood layer (16), a floor covering layer (17) is provided on the inner surface of the plywood layer (16), and a sand layer (18) and a soil and rock layer (19) are provided between the plywood layer (16) and the bottom soil.

6. The construction method of the cut-and-cover arch method according to claim 3, which utilizes a combination of permanent and temporary intermediate slabs as a support system, is characterized in that: The mold (13) includes a concrete substrate (14), and a plywood layer (16) is provided on the inner surface of the concrete substrate (14).

7. The construction method of the cut-and-cover arch method according to claim 1, which utilizes a combination of permanent and temporary intermediate slabs as a support system, is characterized in that: When constructing the supporting arch (2) in step ②, the unit top plate (3) in step ③, the first unit middle plate (4) in step ④, the first unit bottom plate (5) in step ⑤, the second unit middle plate (8) in step ⑦, and the second unit bottom plate (9) in step ⑧, waterproofing construction is carried out between the underground continuous walls (1) on both sides.

8. The construction method of the cut-and-cover arch method according to claim 1, which utilizes a combination of permanent and temporary intermediate slabs as a support system, is characterized in that: The sedimentation tank (6) used in step ⑥ includes a sedimentation tank body (20). A ring frame (21) is detachably installed on the lower part of the sedimentation tank body (20) by bolts. A hand-cranked spandrel (22) is installed at each of the four corners of the ring frame (21). The shell of the hand-cranked spandrel (22) is fixed on the ring frame (21). Lockable universal rollers (23) are installed at the bottom of the telescopic rod of the hand-cranked spandrel (22).

9. A construction method for a cut-and-cover arched structure as described in claim 1, utilizing a combination of permanent and temporary intermediate slabs as a support system, characterized in that: The device used for hydraulic scouring of the soil in step ⑦ includes a traveling vehicle (24), on which a placement seat (25) is installed. The top of the placement seat (25) is provided with a horizontally arranged first slewing bearing (26). A vertically arranged second slewing bearing (27) is installed on the slewing seat of the first slewing bearing (26). A clamping seat (28) is installed on the slewing seat of the second slewing bearing (27). A water spray pipe (29) is installed in the clamping seat (28). The clamping seat (28) is provided with a locking bolt (30). Rotating the locking bolt (30) can lock the water spray pipe (29) in the clamping seat (28). A connected water supply pipe (31) is installed on the water spray pipe (29). A rotatable chisel frame (32) is also provided on the outer periphery of the water spray pipe (29) near the drain. A chisel rod (33) arranged in a circle is installed on the chisel frame (32). Each chisel rod (33) extends outward from the drain along the length of the water spray pipe (29).

10. A construction method for a cut-and-cover arched structure according to claim 9, utilizing a combination of permanent and temporary intermediate slabs as a support system, characterized in that: A drive motor (34) is installed on the water spray pipe (29), and a drive gear (35) is installed on the output shaft of the drive motor (34). The end of the chisel frame (32) is provided with a gear ring (36) that meshes with the drive gear (35). When the drive motor (34) is started, it can drive the chisel frame (32) to rotate relative to the water spray pipe (29). The outer periphery of the water spray pipe (29) is also provided with an annular guide groove (38), and the chisel frame (32) is provided with several sliders (37) that cooperate with the annular guide groove (38).

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