Construction method of mountain steep slope suspended pile cap

Abstract

This invention discloses a construction method for a suspended pier on a steep mountain slope, comprising the following steps: (1) excavating and leveling a multi-tiered construction platform from top to bottom on the upper part of the steep slope; (2) excavating the lower construction platform step by step according to the actual situation; (3) excavating pile foundations at each tier of the construction platform; (4) extending the steel casing after the pile foundation excavation is completed and pouring pile foundation concrete; (5) installing a bracket structure on the top of the extended steel casing; (6) constructing the formwork and binding the reinforcing bars for the pier; (7) pouring and curing the concrete for the pier; and (8) dismantling the bracket structure except for the clamps. This invention is designed for piers located in mountainous areas with complex topography, large ground undulations, and located on cliffs with the bottom part suspended, improving the safety and efficiency of construction of suspended piers on cliffs, reducing damage to the original topography, and achieving green construction.

Description

Technical Field

[0001] This invention relates to the technical field of bridge engineering construction, specifically to a method for constructing suspended piers on steep mountain slopes. Background Technology

[0002] For bridge projects located on steep slopes in mountainous areas, to protect the original topography, reduce excavation, and avoid environmental damage, the bottom of the pier cap is often designed as a partially suspended structure. Currently, most construction methods for suspended pier caps involve building a masonry retaining wall (rubble concrete retaining wall) to support the suspended portion or erecting a steel pipe scaffold to form the construction platform. However, for suspended pier caps located on cliffs, these methods are not only extremely complex and difficult to implement, but some terrains may even make it impossible to erect scaffolds or build retaining walls, posing significant safety hazards. Another method involves pre-embedding corbels within the pile body and then installing steel sections as supports to form the pier cap construction platform. The difficulty of this method lies in embedding pre-embedded parts on the suspended side of the pile body, which presents considerable challenges, and the position of the pre-embedded parts is difficult to control, affecting construction efficiency. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a method for constructing suspended foundations on steep mountain slopes. This invention addresses the challenges of constructing foundations on steep slopes in V-shaped canyons, including significant environmental damage and difficulties in restoring the original ecological landscape. It proposes a method of constructing a steel platform using clamps as load-bearing components on steel casing pile foundations, and then using this platform to pour the suspended foundation. This invention provides a convenient, efficient, and easy-to-implement method for constructing suspended foundations in mountainous terrain with significant elevation changes, located on cliffs, and partially suspended at the base. This improves the safety and efficiency of construction on cliff-side suspended foundations, reduces damage to the original topography, and achieves green construction.

[0004] To achieve the above objectives, this invention provides a construction method for suspended foundation piers on steep mountain slopes. Addressing the challenges of high technical difficulty, significant environmental damage, and difficulty in restoring the original ecological landscape during foundation pier construction on steep slopes of V-shaped canyons, this invention proposes a method that uses clamps installed on the steel casing of the pile foundation as load-bearing components to erect and install a bracket structure, which serves as a construction platform for pouring the suspended foundation pier. The method includes the following steps:

[0005] (1) Excavate and level the upper part of the steep slope of the mountain from top to bottom using a multi-level platform; control the slope gradient during the slope excavation process;

[0006] (2) After the construction platform of the upper step is excavated and leveled, the lower construction platform is excavated step by step according to the actual situation.

[0007] (3) Excavate the pile foundation at the construction platform of each step; when excavating the pile foundation, enlarge the hole diameter by 20-25cm. After the bottom of the hole is stable hard rock and the hole depth is greater than 2m, change the hole diameter to the design hole diameter and continue excavation to provide sufficient space for subsequent pre-embedded steel casing.

[0008] (4) After the pile foundation excavation is completed, the steel casing is extended. The steel casing is extended by flange connection. After the extension is completed to the bottom elevation of the pile cap, the pile foundation concrete is poured.

[0009] (5) Install a bracket structure on the top of the extended steel casing; the bracket structure includes, from bottom to top, a clamp, a sand cylinder, a main beam, a distribution beam, and a steel plate or a wooden board. The clamp is used as a load-bearing component to erect and install the bracket structure, and the clamp is welded to the outer wall of the steel casing.

[0010] (6) Use the bracket structure as the construction platform for the foundation, and carry out the formwork erection and steel reinforcement binding construction of the foundation;

[0011] (7) Carry out the concrete pouring construction of the foundation and carry out concrete curing;

[0012] (8) Remove the bracket structure except for the clamps and complete the construction of the suspended platform on the steep slope of the mountain.

[0013] Preferably, in step (1), the slope ratio is controlled at approximately 1:0.25 for rocky slopes and 1:0.5 for strongly weathered or accretionary rock layers.

[0014] In any of the above schemes, it is preferred that, in step (3), the steel casing is accurately positioned during installation, the top surface of the steel casing is horizontal, and C35 concrete is poured in the gap between the casing and the foundation pit after the steel casing is installed and positioned to fix the casing.

[0015] In any of the above schemes, it is preferred that in step (5), the clamp is a 12mm thick steel plate, the clamp height is 0.5m, a single clamp arrangement is adopted, and the clamp is connected and closed with M24 high-strength bolts. The M24 high-strength bolts are arranged in 4 rows, with 4 bolts in each row.

[0016] In any of the above options, the preferred choice is to use 56C I-beams for the main beam and 22b I-beams for the distribution beams, with a spacing of 30cm between the distribution beams. During installation, to ensure the stability of the entire bracket, U-shaped clips are used to fix the connection between the clamps, the main beam, and the distribution beams. Sand cylinders are used to support the clamps and the main beam to facilitate subsequent dismantling and construction.

[0017] In any of the above schemes, it is preferred that, in step (5), when installing the clamps on the steel casing, a positioning device is used to accurately position the clamps at the designed height of the steel casing. That is, the positioning device is fixed at the predetermined position of the steel casing, and the positioning device can automatically clamp the steel casing. Then, two semi-circular clamps are placed on the upper part of the positioning device and fully aligned, so that the clamps are at the designed height. M24 high-strength bolts are installed at the aligned position and tightened to clamp the steel casing. Finally, the positioning device is removed and the clamps are welded to the outer wall of the steel casing.

[0018] In any of the above schemes, it is preferred that, in step (7), settlement observation points are set on the bracket structure during concrete pouring, and settlement is observed in real time during concrete pouring; the concrete is poured in layers, starting from the steep slope and pouring towards the bracket structure, so as to ensure that the bracket structure produces reasonable settlement deformation.

[0019] In any of the above schemes, it is preferred that, in step (7), the setting time of each layer of concrete is reasonably controlled during the layered pouring of concrete. The next layer of concrete is poured when the concrete of the next layer has reached 75-78% of its initial setting state, so as to ensure reasonable settlement of the bracket structure and prevent concrete cracking caused by settlement of the bracket structure.

[0020] In any of the above solutions, it is preferred that the clamp is welded to the outer wall of the steel casing by different welding methods, with the upper and lower edges of the clamp being welded to the outer wall of the steel casing along the entire circumference.

[0021] In any of the above solutions, it is preferred that when steel plate is used, its thickness is 5mm; when wood plate is used, its thickness is 5cm.

[0022] The beneficial effects of this invention are:

[0023] 1. This invention provides a convenient, efficient, and easy-to-implement construction method for suspended foundations located in mountainous areas with complex topography, large ground undulations, and situated on cliffs with their bottoms partially suspended. This method improves the safety and efficiency of suspended foundation construction on cliffs, reduces damage to the original topography, and achieves green construction.

[0024] 2. Compared with conventional construction methods for such suspended foundations, the present invention has the advantages of lower safety risk, shorter construction period, lower cost, and greater environmental friendliness.

[0025] 3. This invention employs an automatic clamping positioning device for steel casings to accurately position the clamps on the steel casing. Furthermore, the clamps can be removed after installation without damaging the steel casing structure. This overcomes the shortcomings of existing technologies that typically involve welding or installing other structural components (such as welded rebar ends or steel plates) onto the steel casing for positioning, which damages the outer wall structure and affects its structural strength. It also avoids the construction difficulties and large positioning errors caused by directly positioning the clamps on the steel casing due to their large structural weight. Moreover, this positioning device is reusable, simple to operate, and greatly improves the convenience, safety, and accuracy of construction, further ensuring construction quality and efficiency.

[0026] 4. Theoretical calculations and practical demonstrations have shown that the construction method of this invention is feasible for the construction of suspended foundations on steep mountain slopes. It is particularly effective and practical in the construction of bridge foundations in V-shaped canyons. This construction method achieves safe, efficient, and green construction of bridge foundations in canyon areas, reducing construction costs, difficulty, and time, while significantly minimizing environmental damage and pollution. It serves as a good example for ecological protection in fragile areas, providing a reference for similar projects and demonstrating promising application prospects. Brief description of the attached figures

[0027] Figure 1 This is a schematic diagram of the overall structure of the construction method for the suspended pier on a steep slope according to the present invention;

[0028] Figure 2 A structural plan view of the positioning device used in the construction method of the suspended pier on a steep slope according to the present invention;

[0029] Figure 3 This is a structural side view of the positioning device used in the construction method of the suspended pier on a steep slope according to the present invention;

[0030] Figure 4 This is a schematic diagram of the inner ring of the positioning device used in the construction method of the suspended pier on a steep slope according to the present invention.

[0031] Figure 1 In the middle, 1: clamp, 2: main beam, 3: distribution beam, 4: steel plate or wooden board, 5: steel casing, 6: excavation line, 7: terrain line, 8: pile foundation;

[0032] Figure 2-4 In the middle, 9: outer ring sleeve, 10: inner ring movable clamp, 11: fixed buckle, 12: movable retaining ring, 13: drive motor, 14: drive meshing wheel, 15: power module. Detailed Implementation

[0033] The technical solution of this application will be described in detail below with reference to the accompanying drawings and specific embodiments. However, the following embodiments are only used to understand the present invention. The embodiments and features in the embodiments of this application can be combined with each other. This application can be implemented in a variety of different ways as defined and covered by the claims.

[0034] Example 1

[0035] This embodiment uses a bridge project in a province in Northwest China as an example. It employs driven pile foundations with steel casings, and uses two exposed transverse steel casing piles as load-bearing components to construct a support structure for the pier cap. A combination of clamps and I-beams is used to construct the support structure, which serves as the pier cap construction platform. Then, the pier cap formwork is erected, and reinforcement is tied.

[0036] The exposed part of the pile foundation (i.e. the suspended part of the pile cap) is extended to the bottom of the pile cap with a steel casing of 10mm wall thickness. The casing is 50cm above the ground to prevent debris and mud from flowing into the hole.

[0037] Before constructing the pile foundation, only one pile foundation construction platform needs to be excavated. This facilitates the pile foundation construction and reduces the disturbance to the finished pile foundation caused by subsequent excavation.

[0038] See Figure 1 A method for constructing a suspended pier on a steep mountain slope includes the following steps:

[0039] (1) Excavate and level the upper part of the steep slope of the mountain from top to bottom using a multi-level platform; control the slope gradient during the slope excavation process;

[0040] (2) After the construction platform of the upper step is excavated and leveled, the lower construction platform is excavated step by step according to the actual situation.

[0041] (3) Excavate the pile foundation at the construction platform of each step; when excavating the pile foundation, enlarge the hole diameter by 20cm. After the bottom of the hole is stable hard rock and the hole depth is greater than 2m, change the hole diameter to the design hole diameter and continue excavation to provide sufficient space for subsequent pre-embedded steel casing.

[0042] (4) After the pile foundation excavation is completed, the steel casing is extended. The steel casing is extended by flange connection. After the extension is completed to the bottom elevation of the pile cap, the pile foundation concrete is poured.

[0043] (5) Install a bracket structure on the top of the extended steel casing; the bracket structure includes a clamp, a sand cylinder, a main beam, a distribution beam, and a steel plate from bottom to top. The clamp is used as a load-bearing component to erect and install the bracket structure, and the clamp is welded to the outer wall of the steel casing.

[0044] (6) Use the bracket structure as the construction platform for the foundation, and carry out the formwork erection and steel reinforcement binding construction of the foundation;

[0045] (7) Carry out the concrete pouring construction of the foundation and carry out concrete curing;

[0046] (8) Remove the bracket structure except for the clamps and complete the construction of the suspended platform on the steep slope of the mountain.

[0047] In step (1), the slope gradient is controlled at approximately 1:0.25 for rocky slopes and 1:0.5 for strongly weathered or accretionary rock layers.

[0048] In step (3), the steel casing is positioned accurately during installation, and the top surface of the steel casing is horizontal. After the steel casing is installed and positioned, C35 concrete is poured in the gap between the casing and the foundation pit to fix the casing.

[0049] In step (5), the clamp is made of 12mm thick steel plate, the clamp height is 0.5m, and a single clamp arrangement is adopted. The clamp is connected and closed with M24 high-strength bolts. The M24 high-strength bolts are arranged in 4 rows, with 4 bolts in each row.

[0050] The main beam is made of 56C I-beams, and the distribution beams are made of 22b I-beams with a spacing of 30cm. During installation, in order to ensure the stability of the entire bracket, U-shaped clips are used to fix the connection between the clamps, the main beam, and the distribution beams. Sand cylinders are used to support the clamps and the main beams to facilitate subsequent dismantling and construction.

[0051] In step (5), when installing the clamps on the steel casing, a positioning device is used to accurately position the clamps at the designed height of the steel casing. That is, the positioning device is fixed at the predetermined position of the steel casing. The positioning device can automatically clamp the steel casing. Then, two semi-circular clamps are placed on the upper part of the positioning device and fully aligned so that the clamps are at the designed height. M24 high-strength bolts are installed at the aligned position and tightened so that the clamps clamp the steel casing. Finally, the positioning device is removed and the clamps are welded to the outer wall of the steel casing.

[0052] In step (7), settlement observation points are set on the bracket structure during concrete pouring, and settlement is observed in real time during concrete pouring; the concrete is poured in layers, starting from the steep slope and pouring towards the bracket structure, so as to ensure that the bracket structure produces reasonable settlement deformation.

[0053] In step (7), the setting time of each layer of concrete is reasonably controlled during the layered pouring of concrete. The next layer of concrete is poured when the concrete of the next layer has reached 78% of its initial setting state, so as to ensure reasonable settlement of the bracket structure and prevent concrete cracking caused by settlement of the bracket structure.

[0054] The clamps are welded to the outer wall of the steel casing using different welding methods, with the upper and lower edges of the clamps being welded to the outer wall of the steel casing along its full circumference.

[0055] It is made of steel plate with a thickness of 5mm.

[0056] Example 2

[0057] See Figure 1 A method for constructing a suspended pier on a steep mountain slope includes the following steps:

[0058] (1) Excavate and level the upper part of the steep slope of the mountain from top to bottom using a multi-level platform; control the slope gradient during the slope excavation process;

[0059] (2) After the construction platform of the upper step is excavated and leveled, the lower construction platform is excavated step by step according to the actual situation.

[0060] (3) Excavate the pile foundation at the construction platform of each step; when excavating the pile foundation, enlarge the hole diameter by 25cm. After the bottom of the hole is stable hard rock and the hole depth is greater than 2m, change the hole diameter to the design hole diameter and continue excavation to provide sufficient space for subsequent pre-embedded steel casing.

[0061] (4) After the pile foundation excavation is completed, the steel casing is extended. The steel casing is extended by flange connection. After the extension is completed to the bottom elevation of the pile cap, the pile foundation concrete is poured.

[0062] (5) Install a bracket structure on the top of the extended steel casing; the bracket structure includes, from bottom to top, a clamp, a sand cylinder, a main beam, a distribution beam, and a wooden board. The clamp is used as a load-bearing component to erect and install the bracket structure, and the clamp is welded to the outer wall of the steel casing.

[0063] (6) Use the bracket structure as the construction platform for the foundation, and carry out the formwork erection and steel reinforcement binding construction of the foundation;

[0064] (7) Carry out the concrete pouring construction of the foundation and carry out concrete curing;

[0065] (8) Remove the bracket structure except for the clamps and complete the construction of the suspended platform on the steep slope of the mountain.

[0066] In step (1), the slope gradient is controlled at approximately 1:0.25 for rocky slopes and 1:0.5 for strongly weathered or accretionary rock layers.

[0067] In step (3), the steel casing is positioned accurately during installation, and the top surface of the steel casing is horizontal. After the steel casing is installed and positioned, C35 concrete is poured in the gap between the casing and the foundation pit to fix the casing.

[0068] In step (5), the clamp is made of 12mm thick steel plate, the clamp height is 0.5m, and a single clamp arrangement is adopted. The clamp is connected and closed with M24 high-strength bolts. The M24 high-strength bolts are arranged in 4 rows, with 4 bolts in each row.

[0069] The main beam is made of 56C I-beams, and the distribution beams are made of 22b I-beams with a spacing of 30cm. During installation, in order to ensure the stability of the entire bracket, U-shaped clips are used to fix the connection between the clamps, the main beam, and the distribution beams. Sand cylinders are used to support the clamps and the main beams to facilitate subsequent dismantling and construction.

[0070] In step (5), when installing the clamps on the steel casing, a positioning device is used to accurately position the clamps at the designed height of the steel casing. That is, the positioning device is fixed at the predetermined position of the steel casing. The positioning device can automatically clamp the steel casing. Then, two semi-circular clamps are placed on the upper part of the positioning device and fully aligned so that the clamps are at the designed height. M24 high-strength bolts are installed at the aligned position and tightened so that the clamps clamp the steel casing. Finally, the positioning device is removed and the clamps are welded to the outer wall of the steel casing.

[0071] In step (7), settlement observation points are set on the bracket structure during concrete pouring, and settlement is observed in real time during concrete pouring; the concrete is poured in layers, starting from the steep slope and pouring towards the bracket structure, so as to ensure that the bracket structure produces reasonable settlement deformation.

[0072] In step (7), the setting time of each layer of concrete is reasonably controlled during the layered pouring of concrete. The next layer of concrete is poured when the concrete of the next layer has reached 75% of its initial setting state, so as to ensure reasonable settlement of the bracket structure and prevent concrete cracking caused by settlement of the bracket structure.

[0073] The clamps are welded to the outer wall of the steel casing using different welding methods, with the upper and lower edges of the clamps being welded to the outer wall of the steel casing along its full circumference.

[0074] It is made of wood, and its thickness is 5cm.

[0075] Furthermore, to further improve the technical effect of the present invention, in this embodiment, see... Figure 2-4 The positioning device includes an arc-shaped outer ring sleeve, an arc-shaped inner ring retainer, a fixed buckle, a movable retaining ring, a drive motor, a drive engagement wheel, and a power module. The outer ring sleeve forms a U-shaped structure with track grooves on both the upper and lower sections. The inner ring retainer is movably nested within the U-shaped outer ring sleeve. The fixed buckle consists of a fixed ring and a movable latch. The fixed buckle is fixedly mounted on one end of the outer ring sleeve, and the movable retaining ring is fixedly mounted on the free end of the inner ring retainer. The fixed buckle and the movable retaining ring constitute a fastening system.

[0076] The inner ring retainer has a continuous, wavy groove on the side adjacent to the outer ring sleeve, which can engage with the drive engagement wheel driven by the drive motor. Under the drive of the drive motor, the inner ring retainer moves along the trajectory of the outer ring sleeve, causing the movable retaining ring on the free end to finally engage with the fixed buckle, thus completing the clamping and positioning.

[0077] The fixed ring and the movable latch are rotatably connected at one end via a rotating pin and a torsion spring, and at the other end via a stepped contact that restricts the rotation direction of the movable latch. When the inner ring's movable clamp moves the movable latch to the fixed latch and abuts against the movable latch, the movable latch is pushed open by the movable latch. When the movable latch continues to move, the movable latch returns to its starting position under the restoring force of the torsion spring, thus locking the movable latch into the fixed latch.

[0078] The construction process of the positioning device of the present invention is as follows: a) The operator uses hoisting equipment, such as a crane, to place the outer ring clamp at the predetermined position of the steel casing. b) The drive motor rotates, and through the meshing transmission between the drive engagement wheel and the inner ring movable clamp, the inner ring movable clamp and the movable clamp move along a fixed trajectory. c) Driven by the inner ring movable clamp, the movable clamp moves along the fixed trajectory until one end touches the movable latch, and pushes the movable latch to rotate and enter the fixed buckle, locking the movable clamp in the fixed buckle. At this time, the positioning device automatically tightens the steel casing.

[0079] The positioning device of the present invention eliminates the difficulty of cumbersome positioning of large components in existing construction, improves the efficiency and accuracy of clamp positioning, reduces the probability of accidents, and ensures reliable operation of construction safety.

[0080] Example 3

[0081] See Figure 1 A method for constructing a suspended pier on a steep mountain slope includes the following steps:

[0082] (1) Excavate and level the upper part of the steep slope of the mountain from top to bottom using a multi-level platform; control the slope gradient during the slope excavation process;

[0083] (2) After the construction platform of the upper step is excavated and leveled, the lower construction platform is excavated step by step according to the actual situation.

[0084] (3) Excavate the pile foundation at the construction platform of each step; when excavating the pile foundation, enlarge the hole diameter by 23cm. After the bottom of the hole is stable hard rock and the hole depth is greater than 2m, change the hole diameter to the design hole diameter and continue excavation to provide sufficient space for subsequent pre-embedded steel casing.

[0085] (4) After the pile foundation excavation is completed, the steel casing is extended. The steel casing is extended by flange connection. After the extension is completed to the bottom elevation of the pile cap, the pile foundation concrete is poured.

[0086] (5) Install a bracket structure on the top of the extended steel casing; the bracket structure includes a clamp, a sand cylinder, a main beam, a distribution beam, and a steel plate from bottom to top. The clamp is used as a load-bearing component to erect and install the bracket structure, and the clamp is welded to the outer wall of the steel casing.

[0087] (6) Use the bracket structure as the construction platform for the foundation, and carry out the formwork erection and steel reinforcement binding construction of the foundation;

[0088] (7) Carry out the concrete pouring construction of the foundation and carry out concrete curing;

[0089] (8) Remove the bracket structure except for the clamps and complete the construction of the suspended platform on the steep slope of the mountain.

[0090] In step (1), the slope gradient is controlled at approximately 1:0.25 for rocky slopes and 1:0.5 for strongly weathered or accretionary rock layers.

[0091] In step (3), the steel casing is positioned accurately during installation, and the top surface of the steel casing is horizontal. After the steel casing is installed and positioned, C35 concrete is poured in the gap between the casing and the foundation pit to fix the casing.

[0092] In step (5), the clamp is made of 12mm thick steel plate, the clamp height is 0.5m, and a single clamp arrangement is adopted. The clamp is connected and closed with M24 high-strength bolts. The M24 high-strength bolts are arranged in 4 rows, with 4 bolts in each row.

[0093] The main beam is made of 56C I-beams, and the distribution beams are made of 22b I-beams with a spacing of 30cm. During installation, in order to ensure the stability of the entire bracket, U-shaped clips are used to fix the connection between the clamps, the main beam, and the distribution beams. Sand cylinders are used to support the clamps and the main beams to facilitate subsequent dismantling and construction.

[0094] In step (5), when installing the clamps on the steel casing, a positioning device is used to accurately position the clamps at the designed height of the steel casing. That is, the positioning device is fixed at the predetermined position of the steel casing. The positioning device can automatically clamp the steel casing. Then, two semi-circular clamps are placed on the upper part of the positioning device and fully aligned so that the clamps are at the designed height. M24 high-strength bolts are installed at the aligned position and tightened so that the clamps clamp the steel casing. Finally, the positioning device is removed and the clamps are welded to the outer wall of the steel casing.

[0095] In step (7), settlement observation points are set on the bracket structure during concrete pouring, and settlement is observed in real time during concrete pouring; the concrete is poured in layers, starting from the steep slope and pouring towards the bracket structure, so as to ensure that the bracket structure produces reasonable settlement deformation.

[0096] In step (7), the setting time of each layer of concrete is reasonably controlled during the layered pouring of concrete. The next layer of concrete is poured when the concrete of the next layer has reached 76% of its initial setting state, so as to ensure reasonable settlement of the bracket structure and prevent concrete cracking caused by settlement of the bracket structure.

[0097] The clamps are welded to the outer wall of the steel casing using different welding methods, with the upper and lower edges of the clamps being welded to the outer wall of the steel casing along its full circumference.

[0098] It is made of steel plate with a thickness of 5mm.

[0099] Furthermore, to further improve the technical effect of the present invention, in this embodiment, the lower edge of the clamp is first welded to the outer wall of the steel casing along its entire circumference. A ceramic heating element is used to heat the entire circumference area to be welded, preheating it to 120°C. After preheating, carbon dioxide shielded welding is performed at a current of 320A, a voltage of 32V, a welding speed of 300mm / min, and a gas flow rate of 30L / min. After welding, the weld surface is ground, and the weld quality is inspected using thermomagnetic powder.

[0100] After the lower edge of the clamp is welded to the outer wall of the steel casing along its entire circumference, allow it to cool completely and stand for 2 hours. Then, weld the upper edge of the clamp to the outer wall of the steel casing along its entire circumference. Submerged arc welding is used to minimize welding deformation. The weld width for submerged arc welding is 4 cm, the welding current is 520 A, the voltage is 35 V, the welding speed is 650 mm / min, and the temperature is 180℃. After welding, maintain the temperature for 2 hours. Finally, cool to room temperature before performing non-destructive testing.

[0101] This invention employs different welding methods to weld the upper and lower edges of the clamp to the outer wall of the steel casing along the entire circumference. It fully considers the stress performance after welding the clamp and the steel casing at different fixed positions, ensuring the strength and stability of the overall structure after welding. It improves the quality or efficiency of a single welding method, increasing welding quality and efficiency by 45%.

[0102] The above welding process can prevent cracks from forming between the clamp and the steel casing, while also reducing the hardening degree of the weld and heat-affected zone, improving the crack resistance of the weld position; it reduces the complexity of welding construction, improves construction convenience, greatly improves welding efficiency and welding quality, and reduces construction costs.

[0103] In step (7), during the concrete pouring construction of the foundation, concrete pouring equipment is set up, which consists of a concrete feed tank, multiple steep inclined pipes, multiple gentle inclined pipes, and multiple connecting buffer pipes. The steep and gentle inclined pipes are alternately connected by the connecting buffer pipes. The steep inclined pipe has an angle of 55 degrees with the horizontal plane and a length of 5m, the gentle inclined pipe has an angle of 35 degrees with the horizontal plane and a length of 3m, and the connecting buffer pipe has a length of 1m and is in the form of a bend. The bottom of the concrete feed tank is connected to the upper end of the steep inclined pipe. The steep and gentle inclined pipes are fixed to the steep slope by fixed supports to maintain their stability. The alternating connection of the multiple steep and gentle inclined pipes forms a wavy bend in the vertical direction.

[0104] During concrete pouring, a concrete feed hopper can be installed at the height of the slope and connected to the upper end of the steep inclined pipe. Then, it is sequentially connected downwards through a connecting buffer pipe, alternating between the gentle inclined pipe, the steep inclined pipe, the gentle inclined pipe, and so on; and fixed with a fixed bracket. Concrete is poured into the concrete feed hopper, thereby enabling the construction of the foundation concrete below the slope through the above structure.

[0105] The above method enables rapid concrete pouring for the foundation, and the alternating connection of steep and gentle inclined pipes via buffer pipes prevents concrete segregation. It offers a large pouring coverage area and low cost, saving nearly 30% compared to traditional tank truck and pump truck pumping or ground pumping for the same pouring volume. Furthermore, it can be installed and used multiple times, has a simple structure, is easy to install on-site, and is reusable.

[0106] As can be seen from the above embodiments, the present invention provides a convenient, efficient and easy-to-implement construction method for suspended foundations located in mountainous areas with complex topography, large ground undulations, and located on cliffs with the bottom part suspended. This improves the safety and efficiency of construction of suspended foundations on cliffs, reduces damage to the original topography, and achieves green construction.

[0107] Compared with conventional construction methods for such suspended foundations, this invention has the advantages of lower safety risk, shorter construction period, lower cost, and greater environmental friendliness.

[0108] This invention employs an automatic clamping positioning device for steel casings to accurately position the clamps on the steel casing. Furthermore, the clamps can be removed after installation without damaging the steel casing structure. This overcomes the shortcomings of existing technologies that typically involve welding or installing other structural components (such as welded rebar ends or steel plates) onto the steel casing for positioning, which damages the outer wall structure and affects its structural strength. Moreover, this positioning device is reusable, simple to operate, and greatly improves the convenience, safety, and accuracy of construction, further ensuring construction quality and efficiency.

[0109] Theoretical calculations and practical demonstrations have proven the feasibility of using the construction method of this invention for suspended foundation construction on steep mountain slopes. It demonstrates particularly good economic efficiency and practicality in the construction of bridge foundations in V-shaped canyons. This construction method achieves safe, efficient, and green construction of bridge foundations in canyon areas, reducing construction costs, difficulty, and time, while significantly minimizing environmental damage and pollution. It serves as a good example for ecological protection in fragile areas, providing a reference for similar projects and showing promising application prospects.

[0110] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for constructing a mountain steep slope suspended pile cap, characterized in that, The method comprises the following steps: (1) excavating and leveling the upper part of the slope surface of the mountain from top to bottom in multiple steps; controlling the slope gradient during the slope excavation; (2) after the upper step is excavated and leveled, the lower step is excavated according to the actual situation; (3) excavating the pile foundation at each step; the hole diameter is expanded by 20-25 cm during the pile foundation excavation, and the hole diameter is changed to the design hole diameter for continuous excavation after the hole bottom is stable hard rock and the hole depth is greater than 2 m; (4) after the pile foundation is excavated, the steel casing is lengthened, the steel casing is lengthened by using a flange connection method, and the pile foundation concrete is poured after the steel casing is lengthened to the bottom elevation of the pile cap; (5) installing a bracket structure on the top of the lengthened steel casing; the bracket structure comprises, from bottom to top, a hoop, a sand cylinder, a main beam, a distribution beam, a steel plate or a wooden plate, the hoop is used as a force member to install the bracket structure, and the hoop is welded to the outer wall of the steel casing; the positioning device is fixed at a predetermined position of the steel casing, the positioning device can automatically tighten the steel casing, then the two hoop halves are placed on the upper part of the positioning device and are completely closed to make the hoop at the design height, M24 high-strength bolts are installed at the closed position and are tightened to make the hoop tightly clamp the steel casing, finally the positioning device is removed, and the hoop is welded to the outer wall of the steel casing; the positioning device comprises an arc-shaped outer ring sleeve, an arc-shaped inner ring movable hoop, a fixed buckle, a movable clamping ring, a driving motor, a driving meshing wheel and a power module, the outer ring sleeve forms a U-shaped structure with a track groove on the upper and lower sections, and the inner ring movable hoop is movably nested in the outer ring sleeve of the U-shaped structure; the fixed buckle is composed of a fixed ring and a movable clamping tongue; the fixed buckle is fixedly arranged on one end of the outer ring sleeve, and the movable clamping ring is fixedly arranged on the free end of the inner ring movable hoop; the fixed buckle and the movable clamping ring form a clamping system; a continuous wave-shaped concave-convex groove is arranged on the side surface adjacent to the outer ring sleeve of the inner ring movable hoop; (6) using the bracket structure as the construction platform of the pile cap to perform formwork erection and steel bar binding construction of the pile cap; (7) performing concrete pouring construction of the pile cap and performing concrete curing; (8) removing the bracket structure except the hoop to complete the construction of the suspended pile cap of the mountain slope.

2. The method according to claim 1, wherein In the step (1), the stone slope is controlled to be about 1:0.25, and the strong weathered or accumulated rock layer is controlled to be 1:0.

5.

3. The method according to claim 2, wherein In the step (3), the steel casing is accurately positioned during embedding, the top surface of the steel casing is horizontal, and C35 concrete is poured in the gap between the steel casing and the foundation pit to fix the steel casing after the embedding and positioning of the steel casing are completed.

4. The method according to claim 3, wherein In the step (5), the hoop is a 12mm-thick steel plate, the height of the hoop is 0.5m, a single hoop is arranged, the hoop is closed by M24 high-strength bolts, and the M24 high-strength bolts are arranged in 4 rows with 4 in each row.

5. The method according to claim 4, wherein The main beam is selected from 56C I-beams, the distribution beam is selected from 22b I-beams, the distance between the distribution beams is 30cm, a U-shaped clamping is arranged at the connection between the hoop, the main beam and the distribution beam, and the sand cylinder is arranged between the hoop and the main beam.

6. The method according to claim 5, wherein In the step (7), the settlement observation points are arranged on the bracket structure during the concrete pouring construction, and the settlement observation is carried out in real time during the concrete pouring process; the concrete is poured layer by layer, and the pouring is started from the steep slope to the direction of the bracket structure.

7. The method according to claim 6, wherein In the step (7), the setting time of each layer of concrete is reasonably controlled during the layer-by-layer pouring of the concrete, and the pouring of the upper layer of concrete is carried out when the poured concrete of the next layer reaches 75-78% of the initial setting state.

8. The method according to claim 7, wherein The hoop is welded on the outer wall of the steel casing by adopting different welding modes to weld the upper and lower edges of the hoop with the outer wall of the steel casing respectively.

9. The method according to claim 8, wherein When the steel plate is used, the thickness is 5 mm; when the wooden plate is used, the thickness is 5 cm.

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