Combined steel trestle construction method under geological conditions of shallow sea and thin covering layer

Abstract

The invention relates to a combined steel trestle construction method under the geological condition of shallow sea and thin covering layer, which comprises the following steps: arranging a steel trestle in a split manner according to the geological condition, and arranging a transition pier at the split part; in the seabed bare rock area, steel pipe piles are fixed through embedded steel bars and a cast-in-place concrete bearing platform; steel pipe pile arrangement and reinforcement measures are adjusted according to the thickness of a covering layer in a seabed area with the covering layer; reinforcing piers and transverse steel pipe inclined struts are arranged in a deep water area to enhance longitudinal and lateral stability; and the steel trestle is reliably connected with the old wharf and the mountain, so that the overall stability is improved. The construction period can be shortened, cost is reduced, and construction safety is guaranteed.

Description

Technical Field

[0001] The invention relates to the field of underwater steel trestle engineering, in particular to a method for constructing a combined steel trestle under shallow sea and thin cover geological conditions. Background Art

[0002] As China continues to increase its efforts to develop coastal areas, the number of offshore and landscape bridge construction projects is increasing. Steel trestles, as important temporary facilities during construction, are used to transport materials, equipment, and personnel, playing a key role in ensuring the smooth progress of projects. However, traditional construction technologies and methods for steel trestles in shallow waters, tidal areas, and thin overburden geological conditions often fail to meet the needs of these special environments and present a series of problems: 1. Complex geological conditions Shallow waters in shallow waters often present complex and diverse seabed geology. These conditions include exposed rock and sloping rock, making traditional steel trestle foundation construction methods difficult to apply directly. For example, in exposed rock areas, traditional driven pile foundation construction may be hindered by the rock's hardness, hindering construction progress.

[0003] The water level in tidal areas fluctuates dramatically, so the impact of tides on the stability of the steel trestle needed to be considered during construction. The rise and fall of seawater causes the stress conditions in the steel trestle foundation to constantly change, increasing the difficulty and risk of construction.

[0004] In thin overburden geological conditions, the overburden thickness is relatively thin and may not provide sufficient support for the steel trestle. Traditional construction methods in this case may result in insufficient stability of the steel trestle and even the risk of overturning.

[0005] 2. Complex construction environment In some construction areas, there may be abandoned old docks that the steel trestle needs to cross. The structure and stability of the old docks are unknown, which brings additional difficulties to the construction of the steel trestle.

[0006] In the shallow water area near the mountain, waves hitting the mountain will produce surges and back waves. These forces will have a huge impact on the steel pier and affect its stability.

[0007] The end point of the steel trestle needs to be reliably connected to the mountain, which requires a construction method that can ensure the firmness and stability of the connection.

[0008] After searching: Patent CN219930699U proposes a method for constructing a shallow-cover steel trestle. This method increases the stability of steel pipe piles by drilling holes into fully weathered rock and inserting locating rods. However, this method is primarily applicable to fully weathered rock surfaces and has limited applicability to other complex geological conditions, such as bare rock and sloping rock.

[0009] Traditional steel trestle construction methods typically use driven or precast pile foundations. These methods present numerous challenges in shallow waters, tidal zones, and areas with thin overburden, such as difficulty in construction, high costs, and insufficient stability. Summary of the Invention

[0010] The present invention aims to overcome the defects of the existing technology and provide a method for constructing a combined steel trestle under shallow sea and thin cover geological conditions, so as to solve the problems faced by the construction of steel trestle under shallow sea, tidal zone and thin cover geological conditions, complex geological conditions, harsh marine environment, high construction difficulty and limitations of existing technology.

[0011] In order to solve the above-mentioned technical problems, the present invention is achieved as follows: A method for constructing a combined steel trestle under shallow sea and thin overburden geological conditions, characterized in that it comprises the following steps: The steel trestle is divided into sections according to the geological conditions, and transition piers are set at the sections. In the bare rock area on the seabed, steel pipe piles are fixed with embedded steel bars and cast-in-place concrete caps; In areas with seabed overburden, adjust the arrangement of steel pipe piles and reinforcement measures according to the thickness of the overburden; Reinforced piers and transverse steel pipe bracing are installed in deep water areas to enhance longitudinal and lateral stability; Reliably connect the steel trestle to the old pier and the mountain to improve overall stability.

[0012] The method for constructing a combined steel trestle under shallow sea and thin overburden geological conditions is characterized in that the sub-joining arrangement is specifically as follows: The starting section of the pier is the first section, with no seabed cover. The upper structure longitudinal beams are made of section steel with a span of 3m-6m. The second section is from the starting point to the abandoned wharf. The average thickness of the seabed cover is about 5m. The upper longitudinal beam adopts Bailey beam with a span of 12m. The third section spans the abandoned wharf, has no covering layer, a span of 3m-6m, and the upper longitudinal beam adopts a steel structure; The fourth and fifth sections are located in the bare rock section near the bottom of the mountain. The longitudinal beams are made of steel structure with a span of 6m.

[0013] The method for constructing a combined steel trestle under shallow sea and thin cover geological conditions is characterized in that: in the bare rock area on the seabed, reinforcement is planted on the rock and a cast-in-place concrete foundation is used to fix steel pipe piles, and a pre-buried steel plate on the top of the foundation is welded to the steel pipe piles.

[0014] The method for constructing a combined steel trestle under shallow sea and thin cover geological conditions is characterized by further comprising the step of selectively driving inclined piles on both sides of the steel pipe piles according to geological conditions.

[0015] The method for constructing a combined steel trestle under shallow sea and thin overburden geological conditions is characterized in that the specific conditions for driving oblique piles on both sides of the steel pipe piles are: In areas where the seabed geological conditions are bare rock, oblique piles are driven on both sides of the steel pipe piles regardless of the cover conditions; In areas where there is a covering layer on the seabed geology, depending on the depth of the seabed silt, when the silt depth is less than 5m, inclined piles are added to the corresponding pipe piles; when the silt depth exceeds 5m, no inclined piles are added to the corresponding pipe piles.

[0016] The method for constructing a combined steel trestle under shallow-water thin-cover geological conditions is characterized in that: in areas with a cover layer on the seabed, the reinforcement measures refer to adding reinforcement piers and transverse steel pipe braces, specifically: in deep water areas, a group of reinforcement piers is set every three spans, and the reinforcement piers play a longitudinal stabilization role; transverse steel pipe braces are set between the middle piers of the two rows of reinforcement piers, and the steel pipe braces on both sides play a lateral stabilization role.

[0017] The method for constructing a combined steel trestle under shallow sea and thin overburden geological conditions is characterized in that: the reliable connection between the steel trestle, the old wharf and the mountain means that the steel trestle and the old wharf are connected by channel steel, and each row of steel pipe piles are longitudinally connected by channel steel; high and low piers are set at the connection to ensure a smooth transition and improve overall stability.

[0018] The beneficial effects of the present invention are as follows: It can be seen from the above technical scheme that the present application provides a method for constructing a combined steel trestle under shallow sea thin cover geological conditions, which makes full use of the environment around the trestle and connects the trestle with the old wharf and nearby mountains, thereby greatly increasing its overall stability; the method is simple to construct and operate, saving the time and cost of drilling holes; compared with traditional construction processes, the method has simple construction, good stability and low construction cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments: Figure 1 This is a schematic diagram of the steel pipe pile cap at the bare rock location; Figure 2 It is the location of the first and second joints, and the connection processing diagram; Figure 3 This is the second cross-sectional view; Figure 4 Schematic diagram of setting up a group of reinforcement piers every 3 spans for the second joint; Figure 5 Design cross-sectional drawings for the third, fourth, and fifth trestle structures; Figure 6 Cross-sectional drawings of the structural designs for the third, fourth and fifth trestle bridges. DETAILED DESCRIPTION

[0020] The following will clearly and completely describe the technical solutions of the embodiments of the present application in conjunction with the accompanying drawings. Obviously, the embodiments described are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments of the present application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection requested by this application. Example 1 like Figure 1-6 As shown: A method for constructing a combined steel trestle under shallow sea and thin overburden geological conditions, comprising the following steps: 1. Set up the steel trestle in sections according to geological conditions, and set up transition piers at the sections; The branch connection setting is specifically as follows: The starting section of the pier is the first section, with no seabed cover. The upper structure longitudinal beams are made of section steel with a span of 3m-6m. The second section is from the starting point to the abandoned wharf. The average thickness of the seabed cover is about 5m. The upper longitudinal beam adopts Bailey beam with a span of 12m. The third section spans the abandoned wharf, has no covering layer, a span of 3m-6m, and the upper longitudinal beam adopts a steel structure; The fourth and fifth sections are located in the bare rock section near the bottom of the mountain. The longitudinal beams are made of steel structure with a span of 6m.

[0021] 2. In the bare rock area on the seabed, steel pipe piles are fixed with embedded steel bars and cast-in-place concrete caps; Rebar is planted on the rock and a cast-in-place concrete foundation is used to fix the steel pipe piles. The embedded steel plate on the top of the foundation is welded to the steel pipe piles.

[0022] 3. In areas with seabed overburden, adjust the arrangement of steel pipe piles and reinforcement measures according to the thickness of the overburden; The reinforcement measures mentioned above refer to the addition of reinforcement piers and transverse steel pipe braces. Specifically, in deep water areas, a group of reinforcement piers is set up every three spans, and the reinforcement piers play a longitudinal stabilization role; transverse steel pipe braces are set up in the middle piers of the two rows of reinforcement piers, and the steel pipe braces on both sides play a lateral stabilization role.

[0023] 4. Install reinforcement piers and transverse steel pipe bracing in deep water areas to enhance longitudinal and lateral stability; 5. Reliably connect the steel trestle to the old wharf and the mountain to improve overall stability.

[0024] The reliable connection between the steel trestle, the old wharf and the mountain means that channel steel is used to connect the steel trestle and the old wharf, and channel steel is used to connect each row of steel pipe piles longitudinally; high and low piers are set at the connection to ensure a smooth transition and improve overall stability.

[0025] Furthermore, the method also includes the step of selectively driving inclined piles on both sides of the steel pipe piles according to geological conditions.

[0026] The specific conditions for driving oblique piles on both sides of the steel pipe piles are: In areas where the seabed geological conditions are bare rock, oblique piles are driven on both sides of the steel pipe piles regardless of the cover conditions; In areas where there is a covering layer on the seabed geology, depending on the depth of the seabed silt, when the silt depth is less than 5m, inclined piles are added to the corresponding pipe piles; when the silt depth exceeds 5m, no inclined piles are added to the corresponding pipe piles.

[0027] Furthermore, all steel pipe piles are treated with anti-corrosion to extend the service life of the trestle.

[0028] The design of the split-joint arrangement and transition piers, as well as the reliable connection of the trestle to the old pier or nearby mountain, significantly improves the overall stability of the steel trestle in shallow waters, tidal areas, and thin overburden geological conditions. This design fully considers the complex and changing geological conditions and effectively addresses adverse factors such as bare rock, inclined rock, abandoned pier crossings, and wave impact, ensuring the safe operation of the trestle in various environmental conditions.

[0029] The selective placement of inclined piles on both sides of the steel pipe piles, tailored to geological conditions, and the addition of reinforcement piers and transverse steel pipe bracing in deep water areas have significantly enhanced the pier's ability to resist overturning. These designs, particularly in areas subject to strong tidal forces and heavy wave impacts, effectively prevent the pier from capsizing due to external forces, ensuring safety during construction and operation.

[0030] By employing cast-in-place concrete caps, embedded rebar, and pre-buried steel plates, the positioning and securing of steel pipe piles was simplified, eliminating the time-consuming and labor-intensive traditional boring methods. This not only improved construction efficiency but also reduced costs, providing a more economical and efficient solution for similar projects.

[0031] This technical solution fully considers the special construction requirements of shallow waters, tidal areas, and thin overburden geological conditions. By adjusting the type and span of the superstructure longitudinal beams, as well as the placement of inclined piles, the trestle can adapt to the construction requirements of different geological conditions. This flexibility provides reliable technical support for trestle construction in complex geological conditions.

[0032] All steel pipe piles are treated with anti-corrosion treatment to effectively prevent damage caused by seawater corrosion, thereby extending the service life of the pier. This not only reduces subsequent maintenance costs, but also improves the economic and social benefits of the pier.

[0033] Example 2 like Figure 1-6 The specific steps are as follows: Geological survey and sub-joint design: A detailed geological survey is conducted along the pier to clarify the geological conditions of each section, including the distribution of bare rock, thickness of the cover layer, depth of seabed silt, etc.

[0034] According to the results of geological survey, the pier is divided into five sections: the starting section is the first section, with no seabed cover; the starting section to the abandoned wharf is the second section, with an average seabed cover thickness of about 5m; the section across the abandoned wharf is the third section, with no cover; the fourth and fifth sections are near the bottom of the mountain, with longitudinal beams made of steel structure, a span of 6m, and all of them are bare rock sections.

[0035] First joint construction: At the starting section (first leg), due to the lack of seabed cover, steel pipe piles were secured by embedding reinforcement in the rock and casting a concrete cap. A steel plate was pre-embedded on top of the cap and welded to the steel pipe piles for stability.

[0036] Inclined piles are driven on both sides of the steel pipe piles to enhance the anti-overturning ability.

[0037] The upper structure longitudinal beam adopts steel structure with a span of 3m-6m to meet the load-bearing and stability requirements.

[0038] Second joint construction: Entering the deep water area (second link), the average thickness of the seabed cover is about 5m, and the upper longitudinal beam adopts Bailey beam with a span set to 12m.

[0039] A group of reinforcement piers is set up every three spans, and the reinforcement piers play a longitudinal stabilization role; transverse steel pipe diagonal braces are set between the two rows of middle piers of the reinforcement piers, and the steel pipe diagonal braces on both sides play a lateral stabilization role.

[0040] According to the depth of seabed silt, when the silt depth is less than 5m, inclined piles are added to the corresponding pipe piles to enhance the anti-overturning ability.

[0041] The third, fourth and fifth joint construction: The sections across the abandoned wharf (third link) and near the bottom of the mountain (fourth and fifth links) are all bare rock sections, and the span is reduced to 6m to improve structural stability.

[0042] The steel pipe columns are connected longitudinally, and transverse steel pipe braces are set on both sides of each row of steel pipe columns to enhance the overall stability.

[0043] Connection and fixing: The pier and the old wharf are reliably connected using No. 14 channel steel, and each row of steel pipe piles are also longitudinally connected using No. 14 channel steel.

[0044] High and low piers are set at the connection points to ensure smooth transition and improve overall stability.

[0045] Anticorrosion treatment: All steel pipe piles are treated with anti-corrosion methods such as painting with anti-corrosion paint or wrapping with anti-corrosion materials to extend the service life of the pier.

[0046] The construction method of this embodiment successfully completed the construction of a steel trestle in shallow waters, tidal areas, and thin overburden geological conditions. The trestle exhibited excellent overall stability, with no structural instability due to geological conditions or the marine environment. This simplified construction process saved time and expense for drilling holes, reducing construction costs. The trestle also demonstrated strong anti-overturning capabilities, effectively resisting tidal forces and wave impacts, ensuring safety during construction and operation.

[0047] The above are only embodiments provided for this application and are not intended to limit this application. Although this application has been described in detail with reference to the embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. However, any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application should be included in the scope of protection of this application.

Claims

1. A method for constructing a combined steel trestle under shallow sea and thin overburden geological conditions, characterized in that It includes the following steps: The steel trestle is divided into sections according to the geological conditions, and transition piers are set at the sections. In the bare rock area on the seabed, steel pipe piles are fixed with embedded steel bars and cast-in-place concrete caps; In areas with seabed overburden, adjust the arrangement of steel pipe piles and reinforcement measures according to the thickness of the overburden; Reinforced piers and transverse steel pipe bracing are installed in deep water areas to enhance longitudinal and lateral stability; Reliably connect the steel trestle to the old pier and the mountain to improve overall stability.

2. The method for constructing a combined steel trestle under shallow sea and thin overburden geological conditions according to claim 1, characterized in that: The branch connection setting is specifically as follows: The starting section of the pier is the first section, with no seabed cover. The upper structure longitudinal beams are made of section steel with a span of 3m-6m. The second section is from the starting point to the abandoned wharf. The average thickness of the seabed cover is about 5m. The upper longitudinal beam adopts Bailey beam with a span of 12m. The third section spans the abandoned wharf, has no covering layer, a span of 3m-6m, and the upper longitudinal beam adopts a steel structure; The fourth and fifth sections are located in the bare rock section near the bottom of the mountain. The longitudinal beams are made of steel structure with a span of 6m.

3. The method for constructing a modular steel trestle under shallow sea and thin overburden geological conditions according to claim 1, characterized in that: In the bare rock area on the seabed, reinforcement is planted on the rock and a cast-in-place concrete foundation is used to fix the steel pipe piles. The embedded steel plate on the top of the foundation is welded to the steel pipe piles.

4. The method for constructing a modular steel trestle under shallow sea and thin overburden geological conditions according to claim 1, characterized in that: The method also includes the step of selectively driving inclined piles on both sides of the steel pipe piles according to geological conditions.

5. The method for constructing a combined steel trestle under shallow sea and thin overburden geological conditions according to claim 4, characterized in that: The specific conditions for driving oblique piles on both sides of the steel pipe piles are: In areas where the seabed geological conditions are bare rock, oblique piles are driven on both sides of the steel pipe piles regardless of the cover conditions; In areas where there is a covering layer on the seabed geology, depending on the depth of the seabed silt, when the silt depth is less than 5m, inclined piles are added to the corresponding pipe piles; when the silt depth exceeds 5m, no inclined piles are added to the corresponding pipe piles.

6. The method for constructing a modular steel trestle under shallow sea and thin overburden geological conditions according to claim 1, characterized in that: In areas where there is a covering layer on the seabed, the reinforcement measures mentioned above refer to the installation of reinforcement piers and transverse steel pipe braces. Specifically, in deep water areas, a group of reinforcement piers is set up every three spans, and the reinforcement piers play a longitudinal stabilization role; transverse steel pipe braces are set up in the middle piers of the two rows of reinforcement piers, and the steel pipe braces on both sides play a lateral stabilization role.

7. The method for constructing a modular steel trestle under shallow sea and thin overburden geological conditions according to claim 1, characterized in that: The reliable connection between the steel trestle, the old wharf and the mountain means that channel steel is used to connect the steel trestle and the old wharf, and channel steel is used to connect each row of steel pipe piles longitudinally; high and low piers are set at the connection to ensure a smooth transition and improve overall stability.

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