A method for constructing a foundation adjacent to a deep-cut cliff wall

Abstract

The application relates to a construction method of a foundation near a deep-cut cliff, which comprises the following steps: firstly, carrying out local island construction near the deep-cut cliff in the dry season, and setting a convenient path leading to the bottom of the deep-cut cliff; secondly, installing a cofferdam at a cofferdam construction area, so that the cofferdam, the deep-cut cliff and the original riverbed surface jointly form a water-blocking structure; thirdly, carrying out second full-range island construction between the inner side of the cofferdam and the deep-cut cliff, and forming a bored pile working platform; fourthly, carrying out bored pile construction on the bored pile working platform; and finally, carrying out a bearing platform construction. The method makes full use of the advantages of the near shore, introduces the convenient path from the bottom of the deep-cut cliff in the dry season, enters the cofferdam through the convenient path in the later period, changes water construction into pure land construction, greatly saves the construction cost, makes full use of the dry season construction advantage, only needs to carry out local island construction to meet the cofferdam installation condition, and can quickly form an operation surface after the construction access is formed; and the cofferdam and the deep-cut cliff jointly form the water-blocking structure, and the topographic features of the deep-cut cliff are fully utilized.

Description

Technical Field

[0001] This application relates to the field of bridge construction, and in particular to a method for constructing foundations near deep-cut cliffs. Background Technology

[0002] In recent years, with the comprehensive advancement of the 14th Five-Year Plan for Transportation, my country's bridge construction industry has been developing rapidly. As the number of existing bridges increases, cross-river bridge sites are becoming increasingly scarce. More and more bridges are choosing to build their foundations in areas with smooth slate or shallow overburden near the riverbank. This approach reduces the impact of new bridges on waterways by allowing them to cross the river in a single span, and it also makes full use of the existing terrain to reduce construction costs.

[0003] The conventional construction methods for bridge foundations located on thick overburden layers are generally the platform-cofferdam method or the jacket structure method followed by the driving of positioning piles and steel casings. However, for bridge foundation construction in semi-shore and semi-water slate terrain, the conventional methods are limited by the effects of water flow and wind loads, and cannot take advantage of the foundation's proximity to the shore.

[0004] The existing bridge foundation construction on semi-shore and semi-water slate terrain requires the assistance of a large amount of equipment and drilling operations can only be carried out after certain conditions are met. It is impossible to quickly set up the work surface after entering the site, resulting in low construction efficiency. Secondly, it also requires the use of steel platforms on the water, which is purely water-based construction and cannot make full use of the good geological advantages of the slate foundation. Summary of the Invention

[0005] This application provides a method for constructing a foundation near a deep cliff face, in order to solve the problems of low construction efficiency and inability to fully utilize the geological advantages of the smooth slate foundation in related technologies.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for constructing a foundation adjacent to a deep-cut cliff face, comprising:

[0007] During the dry season, the first local island construction was carried out near the deep-cut cliff, and a access road leading to the bottom of the deep-cut cliff was set up; a cofferdam was installed in the cofferdam construction area, so that the cofferdam, the deep-cut cliff and the original riverbed surface together formed a water-blocking structure; a second full-range island construction was carried out between the inner side of the cofferdam and the deep-cut cliff to form a drilling pile working platform; drilling piles were constructed on the drilling pile working platform; and the pile cap was constructed.

[0008] In some embodiments, the installation of a cofferdam at the cofferdam construction area includes the following steps: clearing the original riverbed surface to expose the cofferdam construction area; opening slots in the deep-cut cliff face; installing cofferdam segments at the slots on the original riverbed surface and the deep-cut cliff face; connecting the cofferdam segments into a whole; and fixing the cofferdam to the original riverbed surface and the deep-cut cliff face.

[0009] In some embodiments, the cofferdam segments are connected as a whole, and the specific steps include: connecting two adjacent cofferdam segments as a whole using connectors; and pouring concrete between two adjacent cofferdam segments.

[0010] In some embodiments, the cofferdam is fixed to the original riverbed and the deep-cut cliff. The specific steps include: pouring concrete between the grooves of the cofferdam and the deep-cut cliff; pouring concrete of a set height between the cofferdam and the original riverbed; drilling holes at the designed locations on the concrete and the original riverbed; and installing prestressed anchor cables in the holes to connect the cofferdam and the original riverbed through the prestressed anchor cables.

[0011] In some embodiments, the steps of connecting two adjacent cofferdam segments into a whole using connectors and pouring concrete between two adjacent cofferdam segments are carried out simultaneously on different working faces; before the flood season, the steps of connecting two adjacent cofferdam segments into a whole using connectors, pouring concrete between two adjacent cofferdam segments and inside the cofferdam segments, carrying out a second full-range island construction between the inner side of the cofferdam and the deep-cut cliff, drilling holes at the designed locations on the concrete and the original riverbed surface, and installing prestressed anchor cables in the holes are all completed.

[0012] In some embodiments, the cofferdam is installed during the dry season.

[0013] In some embodiments, when carrying out a second full-range island construction between the inner side of the cofferdam and the deep-cut cliff, the method further includes filling the inside of the cofferdam with soil.

[0014] In some embodiments, the backfilling process inside the cofferdam and the drilling process on the drilling platform are carried out simultaneously.

[0015] In some embodiments, before forming the drilled pile working platform after the second full-range island construction between the inner side of the cofferdam and the deep-cut cliff, the method further includes: hardening the top of the island except for the drilled pile construction location.

[0016] In some embodiments, the original riverbed surface is a smooth slate riverbed surface.

[0017] The beneficial effects of the technical solution provided in this application include:

[0018] This application provides a method for constructing foundations near deep-cut cliffs, which fully utilizes the advantages of being close to the shore. During the dry season, a temporary road is introduced from the bottom of the deep-cut cliff, and later, the construction can be carried out through the temporary road into the cofferdam, transforming the construction from water-based to purely land-based construction, greatly saving construction costs. It also takes full advantage of starting construction during the dry season, requiring only the construction of a local island to meet the cofferdam installation conditions, and can quickly form a working surface after the start of construction. The cofferdam and the deep-cut cliff together form a water-blocking structure, making full use of the terrain features of the deep-cut cliff, simplifying the construction process, and saving on the amount of construction measures. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 The construction site layout diagram provided for the embodiments of this application;

[0021] Figure 2 for Figure 1 Schematic diagram of section 1---1;

[0022] Figure 3 This is a schematic diagram of the connection of cofferdam blocks provided in an embodiment of this application;

[0023] Figure 4 A schematic diagram of the cofferdam installation after the first island construction is completed, provided as an embodiment of this application;

[0024] Figure 5 This is a schematic diagram of concrete pouring provided for an embodiment of this application;

[0025] Figure 6 This is a schematic diagram of prestressed anchor cable construction provided in the embodiments of this application;

[0026] Figure 7 This is a schematic diagram of the second full-range island construction provided in an embodiment of this application;

[0027] Figure 8 This is a schematic diagram of bored pile construction provided in an embodiment of this application;

[0028] Figure 9 This is a schematic diagram of the foundation pit excavation and pile cap construction provided in the embodiments of this application;

[0029] Figure 10 A flowchart illustrating the construction method for foundations on adjacent deep cliff faces provided in this application embodiment.

[0030] In the diagram: 1. Deeply incised cliff face; 2. Access road; 3. Floating crane; 4. Bored pile; 5. First partial island construction; 6. Second full-scale island construction; 7. Working platform; 8. Rotary drilling rig; 9. Steel casing; 10. Cofferdam; 100. Corbel; 101. Connector; 102. Concrete; 103. Construction platform; 104. Prestressed anchor cable; 105. Surcharge ballast; 106. Side plate; 11. Original riverbed surface; 12. Foundation pit; 120. Subbase; 13. Pier; 14. Tower column. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0032] This application provides a method for constructing foundations near deep cliff faces, which can solve the problems of low construction efficiency and inability to fully utilize the good geological advantages of the smooth slate foundation in related technologies.

[0033] See Figures 1 to 10 This application provides a method for constructing a foundation adjacent to a deep cliff face, comprising:

[0034] S1: During the dry season, the first local island construction 5 will be carried out near the deep cliff 1, and a temporary road 2 will be set up to lead to the bottom of the deep cliff 1.

[0035] It should be noted that the foundation refers to the foundation of pier 13, which is located on the shore side near the deeply incised cliff 1. The geology of the pier 13 is smooth slate. During high water levels, the part of pier 13 that is underwater will be exposed above water during normal water levels. Normal water level refers to the water level during the period of the year excluding the summer flood season and the winter dry season, which total about 3 months.

[0036] The purpose of setting up access road 2 is to facilitate the entry of equipment and personnel into the cofferdam 10 via the downhill access road 2 on the bank during construction, changing the construction from water-based to purely land-based construction, which greatly saves construction costs.

[0037] The "partial" aspect of the first phase of partial island construction (Section 5) refers to the partial island construction undertaken during the dry season in areas of the original riverbed that are submerged (excluding areas of the original riverbed exposed above water). Specifically, this involves filling soil around the perimeter of the cofferdam construction area to isolate the submerged portion of the cofferdam construction area from the surrounding water. The purpose of this first phase of partial island construction (Section 5) is to completely isolate the submerged cofferdam construction area from the water, ensuring that all cofferdam construction areas are on land.

[0038] S2: Install cofferdam 10 in the cofferdam construction area so that cofferdam 10 and deep cliff 1 together form a water-blocking structure.

[0039] like Figure 1As shown, the cofferdam 10 is U-shaped and comprises multiple interconnected cofferdam segments, including a bottom cofferdam and a top cofferdam. The bottom cofferdam is fixed to a corbel 100 at its bottom end and includes a truss and side plates 106 fixed to both sides of the truss. The bottom and top cofferdams are fabricated separately. After being manufactured in sections in the factory, the bottom and top cofferdams are transported to the construction site by a transport ship.

[0040] The cofferdam 10 is installed during the dry season. When installing cofferdam 10 in the construction area on the island, the area must first be cleared to expose the original riverbed surface 11, which is a smooth slate surface. A groove is then cut into the deeply incised cliff face 1. Cofferdam sections are then installed on the original riverbed surface 11 and at the groove. During installation, the bottom section of the cofferdam is lifted in sections using a floating crane 3 (or a crawler crane), and installed piece by piece from upstream to downstream. When the bottom section is lowered close to the original riverbed surface 11, its position is adjusted until accurate. Then, an underwater sling is used to compact the gap between the corbel 100 on the bottom section and the original riverbed surface 11. Finally, the floating crane 3 is slowly released.

[0041] After the floating crane 3 (or crawler crane) is released, the bottom section of the cofferdam is anchored to the rock mass on the bank using wire ropes to prevent the bottom section of the cofferdam from overturning. Connecting holes can be installed on the cofferdam sections to ensure that the water levels inside and outside the cofferdam 10 are consistent, allowing the installation of the cofferdam 10 to be unrestricted by water level.

[0042] After the cofferdam segments are installed, they are connected as a whole. Adjacent cofferdam segments are then connected using connectors 101, which are steel interlocks. Underwater sealing concrete 102 is then poured between the two cofferdam segments, within the steel interlocks, to ensure the bottom of the steel interlocks is watertight. Once all cofferdam segments are connected, the gap between the bottom of the side plate 106 of the bottom section cofferdam and the original riverbed surface 11 is sealed, and the cofferdam segments are fixed to the original riverbed surface 11 and the deep-cut cliff 1. During fixing, concrete 102 is poured between the cofferdam segments and the grooves of the deep-cut cliff 1, and simultaneously, underwater sealing concrete 102 of a predetermined height is poured between the cofferdam segments and the original riverbed surface 11. When pouring the sealing concrete 102, it is essential to ensure that the top elevation of the poured concrete 102 is not lower than the design elevation. After the bottom sealing concrete 102 is poured, prestressed anchor cables 104 are constructed by drilling holes at the designed locations on the bottom sealing concrete 102 and the original riverbed surface 11. At this time, a construction platform 103 needs to be set up at the top of the bottom cofferdam, and an anchor cable drilling rig is set up on the construction platform 103. The drilling is carried out using the anchor cable drilling rig, and the drilling depth must not be less than the design requirements. After the drilling is completed, the hole is cleaned, and then the prestressed anchor cables 104 are installed in the hole. The prestressed anchor cables 104 are lowered into the hole, and then grout is poured into the hole to complete the prestressing of the prestressed anchor cables 104, so that the cofferdam segment is connected to the original riverbed surface 11 through the prestressed anchor cables 104.

[0043] S3: A second full-range island construction 6 is carried out between the inner side of the cofferdam 10 and the deep-cut cliff 1 to form a drilled pile working platform 7.

[0044] Before carrying out the second full-range island construction 6 between the inner side of the cofferdam 10 and the deep-cut cliff 1, the anchoring steel wire rope between the bottom section of the cofferdam and the rock mass on the bank is released. Then, the island is gradually filled from the bank to the center of the river on the inner side of the cofferdam 10 to the set height. During the second full-range island construction 6 inside the cofferdam 10, soil is simultaneously filled inside the cofferdam 10, that is, soil is filled between the two side plates 106 of the cofferdam block to the set height.

[0045] After the second full-range island construction 6 is carried out between the inner side of the cofferdam 10 and the deep cliff 1, before the drilling pile working platform 7 is formed, the top of the island needs to be hardened except for the construction position of the drilling pile 4.

[0046] The second full-range island construction 6 refers to the complete filling between the inner side of the cofferdam 10 and the deep-cut cliff 1, increasing the pressure inside the cofferdam 10 to resist high water levels.

[0047] S4: Drill pile 4 is constructed on the drilling pile working platform 7.

[0048] Steel casings 9 are driven into the bored pile 4 at the construction location on the bored pile working platform 7. The steel casings 9 include a first steel casing and a second steel casing. First, the first steel casing is driven in. Then, a rotary drilling rig 8 is used to drill a hole 1.0m to 2.0m below the original riverbed surface 11 at the location where the first steel casing was driven in. The second steel casing is then driven into the position where the first steel casing was driven in, so that the first steel casing fits over the outer surface of the second steel casing. The length of the second steel casing is determined according to the original riverbed elevation, and the diameter of the first steel casing is larger than the diameter of the second steel casing. After the steel casings 9 are driven in, a hole is drilled at the location where the steel casings 9 were driven in, and then concrete 102 is poured into the hole to form the bored pile 4.

[0049] The cofferdam 10 is manufactured in sections in the factory, installed in sections, and adjacent sections are connected together using connectors 101. The pouring of concrete 102 between adjacent sections can be carried out simultaneously on different work faces. That is, after some sections of the cofferdam 10 are manufactured in the factory, they can be installed in the cofferdam construction area while the remaining sections are manufactured simultaneously. After some sections are installed, the remaining sections can be installed while connecting them using connectors 101. After the connectors 101 are installed between adjacent sections, concrete 102 needs to be poured between them. This construction method shortens the construction period and saves costs.

[0050] The backfilling inside the cofferdam 10, the connection between the cofferdam 10 and the original riverbed surface 11 via prestressed anchor cables 104, and the drilling of bored piles 4 on the drilling pile working platform 7 can all be carried out simultaneously on different working faces. That is, after connecting part of the cofferdam 10 to the original riverbed surface 11 via prestressed anchor cables 104, while fixing another part of the cofferdam 10 to the original riverbed surface 11 and the deep-cut cliff 1, the interior of the already fixed cofferdam 10 can be backfilled, and a second full-range island construction 6 can be carried out simultaneously to form the drilling pile working platform 7, on which the drilling piles 4 are then constructed. This construction method shortens the construction period and saves costs.

[0051] Before the flood season, the following steps were completed: connecting two adjacent cofferdam blocks into a whole using connector 101; pouring concrete 102 between and inside the two adjacent cofferdam blocks; carrying out a second full-range island construction 6 between the inner side of the cofferdam 10 and the deep-cut cliff 1; drilling holes at the designed locations on the concrete 102 and the original riverbed surface 11; and installing prestressed anchor cables 104 in the holes.

[0052] S5: Carry out the construction of foundation 13.

[0053] Before constructing the pile cap 13 at the working platform 7 of the bored pile, the top section of the cofferdam needs to be installed on the bottom section of the cofferdam and subjected to surcharge 105. The construction of prestressed anchor cables 104, sand filling, and surcharge 105 within the cofferdam 10 can be carried out simultaneously with the construction of the bored pile 4, which improves construction efficiency and helps to shorten the construction period.

[0054] Before the construction of the foundation 13, the water level during the period from the excavation of the foundation pit 12 to the completion of the foundation 13 construction should be planned and predicted in advance. During the construction of the foundation 13, the water level outside the cofferdam 10 should be ensured not to exceed the normal water level. Then, the steel casing 9 is removed, and the foundation pit 12 is excavated from the top surface of the drilling pile working platform 7 in layers to the design height at the location where the steel casing 9 is inserted. After the foundation pit 12 is excavated, the cushion layer 120 is constructed in the foundation pit 12, the pile head of the drilling pile 4 is broken, and then the reinforcement and formwork of the foundation 13 are installed in the foundation pit 12, and concrete 102 is poured.

[0055] After the foundation 13 is constructed, the area between the foundation 13 and the original riverbed surface 11 will be backfilled and compacted. Then the tower column 14 will be constructed.

[0056] In summary, this invention fully utilizes the advantages of being near the shore. During the dry season, a access road 2 is introduced from the bottom of the deep-cut cliff 1, and later, access to the cofferdam 10 is achieved through the access road 2, transforming water-based construction into purely land-based construction, which greatly saves construction costs. It also takes full advantage of starting construction during the dry season, requiring only local island construction to meet the installation conditions of the cofferdam 10, and can quickly form a working surface after construction begins. The cofferdam 10 and the deep-cut cliff 1 together form a water-blocking structure, making full use of the terrain features of the deep-cut cliff 1, simplifying the construction process, and saving on the amount of construction measures.

[0057] In this invention, the construction of prestressed anchor cables 104, sand filling, and surcharge 105 within the cofferdam 10 can be carried out simultaneously with the construction of bored piles 4, improving construction efficiency and shortening the construction period. At the same time, the construction of prestressed anchor cables 104, sand filling, and surcharge 105 improve the connection strength between the cofferdam 10 and the original riverbed surface 11, ensuring the overall stability of the cofferdam 10. The use of prestressed anchor cables 104 to connect the cofferdam 10 and the smooth slate riverbed into a whole, sharing the load, fully utilizes the advantages of the good original riverbed where the foundation of the pier 13 is located.

[0058] The cofferdam 10 is manufactured and installed in sections, and the cofferdam 10 is directly anchored to the riverbed rock surface, thus avoiding the need for trenching construction on the original underwater riverbed surface 11.

[0059] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0060] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0061] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method of constructing a foundation adjacent to a deep undercut cliff wall, characterised by, It comprises: The first local island building (5) is constructed near the deep-cut cliff wall (1) in the dry season, and a convenient path (2) leading to the bottom of the deep-cut cliff wall (1) is arranged; The cofferdam (10) is installed at the cofferdam construction area, so that the cofferdam (10), the deep-cut cliff wall (1) and the original riverbed surface (11) jointly form a water-blocking structure; The second full-range island building (6) is constructed between the inner side of the cofferdam (10) and the deep-cut cliff wall (1), and a bored pile working platform (7) is formed; The bored pile (4) is constructed on the bored pile working platform (7); The pile cap (13) is constructed; The first local island building (5) insulates the part of the cofferdam construction area in the water from the surrounding area, so that all the cofferdam construction area is a land area; The cofferdam (10) is installed at the cofferdam construction area, and the specific steps include: The cofferdam construction area is cleaned to the original riverbed surface (11) to be exposed; A notch is formed in the deep-cut cliff wall (1); The cofferdam block segments are installed on the original riverbed surface (11) and the notch on the deep-cut cliff wall (1); The cofferdam block segments are connected into a whole; The cofferdam (10) is fixed with the original riverbed surface (11) and the deep-cut cliff wall (1); The cofferdam block segments are connected into a whole, and the specific steps include: Two adjacent cofferdam block segments are connected into a whole through the connecting piece (101); The concrete (102) is poured between the two adjacent cofferdam block segments; The cofferdam (10) is fixed with the original riverbed surface (11) and the deep-cut cliff wall (1), and the specific steps include: The concrete (102) is poured between the notch of the cofferdam (10) and the deep-cut cliff wall (1); The concrete (102) of a specified height is poured between the cofferdam (10) and the original riverbed surface (11); Holes are drilled at the designed positions on the concrete (102) and the original riverbed surface (11); The prestressed anchor cable (104) is arranged in the holes, so that the cofferdam (10) is connected with the original riverbed surface (11) through the prestressed anchor cable (104); The steps of connecting two adjacent cofferdam block segments into a whole through the connecting piece (101) and pouring the concrete (102) between the two adjacent cofferdam block segments are simultaneously performed at different working faces; Before the flood season comes, the steps of connecting two adjacent cofferdam block segments into a whole through the connecting piece (101), pouring the concrete (102) between the two adjacent cofferdam block segments and inside the cofferdam block segments, constructing the second full-range island (6) between the inner side of the cofferdam (10) and the deep-cut cliff wall (1), drilling holes at the designed positions on the concrete (102) and the original riverbed surface (11), and arranging the prestressed anchor cable (104) in the holes are all completed; When the cofferdam block segments are installed, the bottom cofferdam block is lifted by the floating crane (3), and is installed in the direction from the upstream to the downstream; The steps of filling the cofferdam (10) inside, connecting the cofferdam (10) with the original riverbed surface (11) through the prestressed anchor cable (104), and constructing the bored pile (4) on the bored pile working platform (7) are simultaneously performed at different working faces.

2. The method of constructing a foundation adjacent a deep undercut cliff wall of claim 1, wherein: The cofferdam (10) is installed in the dry season.

3. The method of constructing a foundation adjacent a deep undercut cliff wall of claim 1, wherein: The method further comprises: Filling the inside of the cofferdam (10) with earth.

4. The method of constructing a foundation adjacent a deep undercut cliff wall of claim 3, wherein: The filling of the inside of the cofferdam (10) with earth and the construction of the bored piles (4) on the bored pile work platform (7) are carried out simultaneously.

5. The method of constructing a foundation adjacent a deep undercut cliff wall of claim 1, wherein, The method further comprises: Hardening the top of the island, except for the position of the bored piles (4).

6. The method of constructing a foundation adjacent a deep undercut cliff wall of claim 1, wherein: The original river bed surface (11) is a light slate river bed surface.

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