Construction Method of Gravity Wharf Foundation in Harsh Sea Conditions Based on Platform-Type Leveling Vessel

Abstract

This invention discloses a method for constructing gravity-type wharf foundations under adverse sea conditions using a platform-type leveling vessel, belonging to the field of hydraulic engineering technology. The method includes: moving the platform-type leveling vessel to the construction area and positioning it; jacking the vessel to remove it from the area affected by adverse sea conditions; laying continuous ridges using serpentine riprap; wherein the center-to-center distance between adjacent ridges is 4.0 to 5.0 times the designed leveling thickness, and the top width of the furrow between adjacent ridges is 0.9 to 1.1 times the designed leveling thickness; repeating the laying until the ridges and furrows together cover the area of ​​the gravity-type wharf foundation to be constructed; inspecting the gravity-type wharf foundation and verifying it through water depth surveying; calculating the reduction in foundation bearing capacity caused by the furrows to ensure that the design requirements of the gravity-type wharf are met. The gravity-type wharf foundation construction method provided by this invention can achieve stable construction of gravity-type wharf foundations under adverse sea conditions, ensuring that the foundation bearing capacity and settlement performance meet standards, with high construction efficiency and low stone cost.

Description

Technical Field

[0001] This invention belongs to the field of water conservancy engineering technology, and in particular relates to a method for constructing gravity wharf foundations under harsh sea conditions based on a platform-type leveling vessel. Background Technology

[0002] The construction of gravity-type wharf foundations is a core component of port engineering, and its quality directly affects the stability of the project. Traditional construction employs a full-laying process: first, riprap is dumped to form the bottom layer of the foundation, then two layers of riprap are laid on top, and finally, crushed stone is used for fine leveling, with a leveling accuracy of approximately ±5cm. However, this process relies on manual labor, resulting in loosely laid stones and a longer subsequent settlement period, thus having inherent limitations.

[0003] When the construction site is located at the ends of two closely spaced breakwaters, the shortcomings of traditional methods are further amplified by the harsh environment: the sea conditions in this area are complex, with high current speeds and the influence of medium- and long-period waves, leading to unstable anchoring of construction vessels and making all-weather operation difficult; at the same time, the currents around the breakwater head area can easily erode the rocks, causing displacement. Under these conditions, the traditional full-lay design is prone to causing the placement of the rocks to deviate, resulting in problems such as excessively thick local accumulation or gaps in the paving, ultimately leading to rework due to failure to meet design requirements, significantly increasing the construction period and cost.

[0004] Currently, there is no dedicated solution for this scenario in existing technology. Ordinary rock-dumping leveling vessels lack jacking and wave-avoidance functions, cannot escape the direct interference of waves and currents, and are difficult to adapt to such harsh sea conditions. If a platform-type leveling vessel specifically designed for immersed tunnel construction is used, its pile-insertion and jacking function can cope with harsh sea conditions. However, the construction characteristics of the platform-type leveling vessel dictate that the foundation bed will inevitably form a ridged structure, which is completely different from the stress mode of the traditional fully-laid foundation bed. This ridged structure may reduce the actual bearing area of ​​the foundation bed, leading to problems such as insufficient bearing capacity and excessive settlement, and failing to meet the design requirements of gravity-type wharves.

[0005] In summary, existing technologies lack construction equipment and processes adapted to the harsh sea conditions at the breakwater ends, and cannot resolve the incompatibility between platform-type leveling ditch foundation beds and traditional gravity-type wharf design standards. Therefore, it is urgent to develop a gravity-type wharf foundation bed construction method for this special scenario. Summary of the Invention

[0006] In view of the shortcomings of the related technologies, the purpose of this invention is to provide a gravity-type wharf foundation construction method based on a platform-type leveling vessel under severe sea conditions, so as to solve the problems mentioned in the background technology.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for constructing gravity-type wharf foundations under harsh sea conditions based on a platform-type leveling vessel includes the following steps:

[0009] S1. Move the platform-type leveling vessel with lifting function to the construction area and position it, then lift it to remove the hull from the area affected by the severe sea conditions.

[0010] S2. The riprap of the platform-type leveling vessel is laid in a serpentine path along the length of the gravity wharf foundation bed to be constructed, starting from the construction starting point, forming continuous ridges with adjacent ridges parallel to each other; the center-to-center distance between adjacent ridges is... The design leveling thickness of the gravity wharf foundation bed to be constructed. The width of the furrow top formed between adjacent ridges is 4.0 to 5.0 times that of adjacent ridges. For design leveling thickness 0.9 to 1.1 times;

[0011] S3. Repeat step S2 to lay the ridges until the ridges and furrows together cover the entire gravity wharf foundation area to be constructed.

[0012] S4. The gravity-type wharf foundation was inspected along the extension direction of the embankment using underwater acoustic detection devices mounted on the riprap pipes, combined with water depth surveying and analysis to verify the center-to-center spacing. and furrow top width Meets the design leveling thickness in step S2 The proportions are well-defined, with no overlapping material and no obvious defects such as excessively wide furrows;

[0013] S5. Calculate the reduction in subgrade bearing capacity caused by furrows, and determine whether the reduction is within a reasonable range to ensure that the subgrade bearing capacity and settlement performance meet the design requirements of gravity wharf.

[0014] In some embodiments, during step S2, when laying continuous ridges, the distance between the bottom of the riprap pipe and the top of the ridge is 0.3 to 0.8 m.

[0015] In some embodiments, during step S2, when laying the continuous ridge, the height of the stones inside the riprap is maintained at the designed leveling thickness. The weight of the stone is 8.0 to 18.0 times that of the stone itself, so as to pre-compact the ridge with the weight of the stone.

[0016] In some embodiments, in step S5, the preset reasonable range is... Calculate the percentage reduction in subgrade bearing capacity caused by furrowing. and ,in:

[0017]

[0018]

[0019] And judge and To ensure that the reduction in the bearing capacity of the subgrade is within a certain range Within a reasonable range, meeting the design requirements of gravity-type wharves; among which, The percentage reduction is based on the maximum bearing capacity of the vertical projection of the furrow. The percentage reduction in the ultimate bearing capacity of furrows due to slope. The width of the furrow top of adjacent ridges. This represents the center-to-center distance between adjacent ridges.

[0020] In some embodiments, during the acceptance of the gravity-type wharf foundation in step S4, the distance between the bottom of the riprap pipe and the top of the ridge is 0.2 to 0.5 m.

[0021] In some embodiments, in step S2, the laying direction of the continuous ridge extends at an angle of 0° to 30° with the dominant direction of water flow or waves in the construction area, so as to reduce the impact of water flow or waves on the ridge and the riprap.

[0022] In some embodiments, during step S2, when laying the continuous ridge, the moving speed of the riprap is 1.3 to 1.5 m / min.

[0023] In some embodiments, during the acceptance of the gravity-type wharf foundation in step S4, the moving speed of the riprap is 2.0 m / min.

[0024] In some embodiments, in step S2, two stones are used as the stone material for laying the continuous ridge.

[0025] In some of these embodiments, the diopside grains have a diameter of 8–15 cm.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] 1. The gravity-type wharf foundation construction method under severe sea conditions based on a platform-type leveling vessel provided by this invention utilizes the lifting function of the platform-type leveling vessel to remove the hull from the influence of severe sea conditions, avoiding interference from sea conditions, significantly improving the safety and stability of construction under severe sea conditions, reducing the risk of construction delays, and ensuring the quality of foundation construction; by optimizing the size ratio of the ridges and furrows, it avoids the waste of stone materials caused by stacking materials on the ridges and prevents the load-bearing hazards caused by excessively wide furrows, providing a flat and uniform stress foundation for the subsequent installation of wharf caissons, reducing the workload of caisson leveling, and indirectly improving the overall project efficiency.

[0028] 2. The gravity wharf foundation construction method for harsh sea conditions based on a platform-type leveling vessel provided by this invention, during the ridge laying stage, maintains the height of the stone material in the riprap pipe that is adapted to the design leveling thickness of the foundation, and uses the self-weight of the stone material to pre-compress the ridge in real time, which can make the stone material generate a moderate amount of compression in advance and improve the density, laying the foundation for the structural stability of the gravity wharf in long-term operation, while reducing the workload of additional compaction processes and helping to control construction costs.

[0029] 3. The gravity-type wharf foundation construction method for harsh sea conditions based on a platform-type leveling vessel provided by this invention reduces the bearing capacity of the foundation caused by furrows. , The quantitative calculation and reasonable range judgment can accurately assess the actual impact of furrows on the subgrade stress, fill the gap in the lack of quantitative assessment standards for bearing capacity when applying furrow subgrades to gravity wharves in traditional processes, avoid the later structural hazards caused by the lack of assessment, ensure that the bearing capacity and settlement performance of the subgrade are adapted to the design requirements of gravity wharves, provide quantifiable basis for the safe acceptance of the project, and reduce the risk of rework caused by performance misjudgment. Attached Figure Description

[0030] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0031] Figure 1 This is a flowchart illustrating an embodiment of the gravity-type wharf foundation construction method based on a platform-type leveling vessel under adverse sea conditions according to the present invention.

[0032] Figure 2 This is a schematic diagram of the cross-sectional structure of a ridge body in an embodiment of the gravity-type wharf foundation construction method based on a platform-type leveling vessel under severe sea conditions according to the present invention.

[0033] Figure 3 This is a schematic diagram showing the height of the riprap pipe during the laying of a continuous ridge in a gravity-type wharf foundation construction method under adverse sea conditions based on a platform-type leveling vessel, according to an embodiment of the present invention.

[0034] Figure 4 This is a schematic diagram of the height of the riprap pipe during the acceptance of a gravity wharf foundation construction method based on a platform-type leveling vessel under adverse sea conditions, according to an embodiment of the present invention.

[0035] Figure 5 This is a schematic diagram of the plan layout of the platform leveling vessel laying the ridge foundation bed, which is an embodiment of the gravity wharf foundation bed construction method based on the platform leveling vessel under severe sea conditions according to the present invention.

[0036] Figure 6This is a schematic diagram comparing the center-to-center spacing of different ridges and the top width of the furrow in one embodiment of the gravity-type wharf foundation construction method based on a platform-type leveling vessel under severe sea conditions according to the present invention.

[0037] Figure 7 This is a comparison of the scanning dimensions of an underwater acoustic detection device in an embodiment of the gravity-type wharf foundation construction method based on a platform-type leveling vessel under harsh sea conditions, according to an embodiment of the present invention.

[0038] In the picture:

[0039] 1. Platform leveling vessel; 2. Rock dumping pipe; 3. Underwater acoustic detection device; 4. Gravity-type wharf foundation; 41. Ridge; 42. Furrow. Detailed Implementation

[0040] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0041] In the description of this invention, it should be understood that the terms "center", "lateral", "longitudinal", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention 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. Therefore, they should not be construed as limitations on this invention.

[0042] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" 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 direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0043] Example 1:

[0044] See appendix Figures 1 to 7 This paper presents an illustrative embodiment of the gravity-type wharf foundation construction method based on a platform-type leveling vessel under severe sea conditions proposed in this invention.

[0045] This embodiment is applied to the construction of the foundation bed at the end of a breakwater. This area is the intersection of two closely spaced breakwater ends, where the sea conditions are harsh: a maximum water depth of 27m, a maximum current velocity of 4 knots, and the influence of medium-to-long-period waves (wave height 0.5m, wave period less than 5s), resulting in less than 30% of the effective working days. Furthermore, the breakwater head forms a bypass flow, and traditional full-lay foundation bed construction is prone to problems such as stone erosion and displacement, and unstable ship anchorages, leading to a high rework rate. Under these harsh sea conditions, the gravity-type wharf foundation bed construction method includes the following steps:

[0046] S1. Move the platform-type leveling vessel 1 with lifting function to the construction area and position it, and lift it to remove the hull from the area affected by the bad sea conditions.

[0047] S2, the riprap 2 of the platform-type leveling vessel 1 is laid in a serpentine path along the length of the gravity wharf foundation 4 to be constructed from the starting point of construction, forming continuous ridges 41, with adjacent ridges 41 parallel to each other; wherein, the center-to-center distance between adjacent ridges 41 is... The design leveling thickness of the gravity wharf foundation 4 to be constructed. The top width of the furrow 42 formed between adjacent ridges 41 is 4.0 to 5.0 times that of the ridges 41. For design leveling thickness 0.9 to 1.1 times;

[0048] S3. Repeat step S2 to lay the ridge 41 until the ridge 41 and the furrow 42 together cover the entire gravity wharf foundation 4 area to be constructed.

[0049] S4. The underwater acoustic detection device 3 on the riprap pipe 2 is used to inspect the gravity wharf foundation 4 along the extension direction of the ridge 41. The center spacing is verified by combining water depth measurement and analysis. and furrow top width 42 Meets the design leveling thickness in step S2 The proportions are well-defined, with no overlapping material and no obvious defects such as excessively wide furrows;

[0050] S5. Calculate the reduction in subgrade bearing capacity caused by furrow 42, and determine whether the reduction is within a reasonable range to ensure that the subgrade bearing capacity and settlement performance meet the design requirements of gravity wharf.

[0051] See appendix Figure 1 This is a flowchart of the method in this embodiment. Step S1 involves using a platform-type leveling vessel 1 to lift the structure away from the rough sea conditions, ensuring construction safety and stability. Step S2 optimizes the size ratio of the ridge body 41 and the furrow 42 to avoid stone waste and potential load-bearing hazards. (See attached diagram for details.) Figure 2 This is a schematic diagram of the cross-sectional structure of the ridge in this embodiment, which clearly shows the center-to-center spacing of this embodiment. 42mm top width of furrow and design leveling thickness By combining the acceptance and bearing capacity calculations of steps S4 and S5, the performance of the subgrade meets the standards, significantly improving construction efficiency and quality under harsh sea conditions and reducing the risk of project delays.

[0052] Before construction, a comprehensive comparison of the performance of platform-type leveling vessel 1 and frame-type leveling vessel in terms of current resistance and leveling accuracy was conducted. Platform-type leveling vessel 1, equipped with pile driving and lifting capabilities, was selected. Its measurement and control system was modified, replacing the original GPS positioning system with a domestically produced BeiDou system. Data frequency conversion software was developed to solve the matching problem between the BeiDou equipment's data output frequency and the leveling vessel's control system, ensuring a positioning accuracy of ±10cm. Simultaneously, based on the ±30cm height difference after foundation compaction, the design leveling thickness was determined. =0.5m, in step S2, the stones used for laying the continuous ridge 41 are two-piece stones, and the particle size of the two-piece stones is limited to 8-15cm. Two-piece stones have sharp edges, good permeability, and high compressive strength, which can ensure the stability of the ridge 41 structure and reduce the scouring of the subgrade by water flow, and are suitable for the long-term stress requirements of gravity wharf subgrade. Limiting the particle size of the two-piece stones to 8-15cm avoids the blockage of the stone throwing pipe 2 due to the particle size being too small, and also prevents the laying from being too loose due to the particle size being too large, ensuring smooth stone delivery and uniform overall density of the ridge 41, thereby improving the load-bearing capacity of the subgrade.

[0053] To determine the optimal center-to-center spacing of the ridge 41 in step S2 and furrow top width This embodiment conducted a comparative experiment with the following steps:

[0054] Step S201: Determine the design leveling thickness of the test substrate. =0.5m, select two pieces of stone with a particle size of 8-15cm, consistent with the project, as the test stone material, and delineate the test area to ensure consistency with the actual construction scene.

[0055] Step S202: Lay five parallel ridges 41 continuously along the length of the test area in a serpentine path. The five ridges 41 are arranged sequentially, with the center-to-center distance between adjacent ridges 41 being... The values ​​were set to 2.1m, 2.2m, 2.3m, and 2.4m respectively.

[0056] Step S203: After the five continuous ridges 41 are laid, an underwater acoustic detection device 3 is used to scan the entire length of the ridges 41 along their extension direction. Combined with water depth measurement data, the top width of the furrow 42 formed between each ridge 41 and the adjacent ridges 41 is recorded. The results were 0.3m, 0.4m, 0.5m, and 0.6m respectively; by scanning and comparing the dimensions using the underwater acoustic detection device 3, it was determined whether there were defects such as material stacking or furrow collapse.

[0057] Step S204: Analyze the experimental results; see appendix for details. Figure 6 and attached Figure 7 The figures show a structural comparison diagram of the center-to-center spacing of different ridges 41 and the top width of the furrows 42, and a comparison diagram of the scanning dimensions measured by the underwater acoustic detection device 3. It can be seen that when... m、 m and m、 When m, the furrow 42 is not obvious, meaning the top width of the furrow 42 is too small, and the edges of adjacent ridges 41 overlap, posing a significant risk of material stacking, which can easily lead to stone waste and uneven stress. When m、 At m, furrow 42 is obvious, meaning the top width of furrow 42 is too large, and the surface of the foundation bed is significantly undulating, which may lead to uneven stress during subsequent caisson installation; when m、 At m, the top width of furrow 42 is moderate, with no material overlap, and the shape of furrow 42 is regular. Therefore, the optimal construction parameters are preliminarily determined to be: m、 m, at this time , 。

[0058] Step S205: Calculate the reduction in subgrade bearing capacity caused by a 0.5m wide furrow 42 using the preliminarily determined optimal construction parameters. The reasonable range for the reduction in subgrade bearing capacity caused by furrow 42 is preset to be [8.5%, 18%]. (See attached...) Figure 6 Taking the foundation bed of three ridges 41 as an example, the foundation bed width is 2.3 + 2.3 = 4.6m, and the furrow width 42 is 0.5 + 0.5 = 1m. Calculate the percentage reduction in the foundation bed bearing capacity caused by the furrow 42, where the maximum percentage reduction in bearing capacity of the vertical projection of the furrow 42 is... The ultimate bearing capacity of furrow 42 is reduced by a certain percentage due to the slope. .

[0059] right and The calculation first clarifies that, in this embodiment, the stone material used for the subgrade paving (two-piece stones, particle size 8-15cm) and the compaction density of the pre-compacted stone-laying pipe 2 (maintaining the stone height inside the stone-laying pipe 2) are consistent. Therefore, the unit area bearing capacity... The same (i.e., stones of the same area can withstand the same load). In addition, the reduction in bearing capacity is essentially "the amount of bearing capacity loss caused by furrows ÷ the total bearing capacity when fully paved without furrows".

[0060] Corresponding to the maximum bearing capacity reduction ratio for "grooves with vertical sidewalls (no slope)," "one ridge 41 + one furrow 42" is selected as a single calculation unit (total unit width = center-to-center distance between adjacent ridges). + furrow top width ).

[0061] When fully paved without furrows (42mm): Total bearing capacity of a single unit At this point, the entire unit area participates in load-bearing;

[0062] When the furrow 42 has vertical sidewalls: the furrow 42 does not participate in the load bearing at all, and the total load bearing capacity of a single unit is... At this point, only 41 square meters of the ridge area are involved in bearing the load;

[0063] load-bearing capacity loss ;

[0064] but .

[0065] The ultimate bearing capacity of the natural slope in the 42 ridge in actual construction is reduced by a certain percentage (the natural accumulation of two stones will form a stable slope, and the stones in the slope part can participate in the bearing).

[0066] When there is a sloping furrow 42: the effective bearing area of ​​furrow 42 needs to be corrected, and the horizontal projection width of the slope is... ,Right now The width of the furrow 42 does not participate in the load-bearing capacity; the total load-bearing capacity of a single unit. At this time, the total area of ​​the ridge 41 and the area of ​​the furrow 42 The width and slope area both contribute to the load-bearing capacity;

[0067] load-bearing capacity loss ;

[0068] but .

[0069] In this embodiment, the maximum bearing capacity reduction ratio of the vertical projection of the furrow 42 is:

[0070]

[0071] The percentage reduction in ultimate bearing capacity of furrow 42 due to slope is:

[0072]

[0073] satisfy and It can be seen that the reduction in the bearing capacity of the subgrade is within a reasonable range of [8.5%, 18%], meeting the design requirements of a gravity-type wharf. Therefore, the optimal construction parameters can be determined as follows: m、 m, at this time , This satisfies the stress requirements while avoiding waste of stone.

[0074] Simplifying the above calculation formula, in step S5, the preset reasonable range is: Calculate the percentage reduction in subgrade bearing capacity caused by furrow 42. and ,in:

[0075]

[0076]

[0077] And judge and To ensure that the reduction in the bearing capacity of the subgrade is within a certain range Within a reasonable range, meeting the design requirements of gravity-type wharves; among which, The proportion of the maximum bearing capacity of the vertical projection of furrow 42 is reduced. The percentage reduction in the ultimate bearing capacity of furrow 42 due to slope. The width of the furrow 42 of the adjacent ridge 41 is the top width. The center-to-center distance between adjacent ridges 41.

[0078] In this embodiment, the reasonable range is [8.5%, 18%]. (Through) , The impact of furrow 42 on bearing capacity is quantitatively calculated, and the criteria for judging reasonable ranges are clarified. This fills the gap in the traditional process of assessing the bearing capacity of the subgrade bed without quantitative basis, ensuring that the bearing capacity of the subgrade bed matches the design requirements and avoiding potential structural safety hazards in the later stages.

[0079] Specifically, the endpoint values ​​of the reasonable range [8.5%, 18%] are for the special working conditions of this embodiment, namely, the construction area is the intersection of the ends of two breakwaters with a relatively close distance, the sea conditions are severe: the maximum water depth is 27m, the maximum current velocity is 4 knots, and two pieces of stone with a particle size of 8-15cm are used as paving stones. The technicians preset these values ​​based on the stress theory of gravity-type wharf foundation and the construction experience of similar discontinuous foundations (similar to the structure of ridge 41-ditch 42) to limit the acceptable range of the influence of ditch 42 on the bearing capacity of the foundation under this working condition.

[0080] It should be noted that the endpoint values ​​of the reasonable range are not fixed and can be flexibly adjusted according to the actual construction conditions: when the sea conditions in the construction area are gentler (e.g., current velocity ≤ 2 knots) and the caisson load is smaller (e.g., single caisson weight ≤ 3000t), the impact of trench 42 on the stability of the subgrade is smaller, and this range can be appropriately expanded; when the sea conditions in the construction area are more severe (e.g., current velocity ≥ 5 knots), the caisson load is larger (e.g., single caisson weight ≥ 5000t) or the foundation bearing capacity is weaker, the requirements for the stress stability of the subgrade are higher, and this range can be appropriately reduced.

[0081] The aforementioned interval endpoints are merely pre-control parameters under specific operating conditions in this embodiment. Those skilled in the art can apply the parameters disclosed in this embodiment. , The quantitative calculation method, combined with theoretical understanding and practical experience of its own construction conditions, flexibly sets appropriate interval endpoint values, which does not affect the understanding and actual implementation of this technical solution at all.

[0082] In this embodiment, the reduction ratio of the subgrade bearing capacity is limited to a preset reasonable range. The internal design aims to achieve a triple balance between meeting load-bearing capacity standards, construction feasibility, and cost control. A detailed analysis follows:

[0083] If we blindly pursue the lowest possible reduction in load-bearing capacity, then we need to reduce the top width of the furrow (42mm). While this can be achieved, the comparative experiments in this embodiment have clearly verified its drawbacks: when At time m, obvious material overlap will appear at the edges of adjacent ridges 41. See Appendix. Figure 6 , Figure 7 middle m、 m and m、 The test group with m will lead to stone waste on the one hand, as the amount of two stones used per ship position increases compared to the case without stacking, significantly increasing construction costs; on the other hand, it will cause uneven compaction of the foundation bed, with low stone compaction in the stacked area and high stone compaction in the non-stacked area, resulting in the settlement difference after the caisson is installed exceeding the allowable deviation of the specification.

[0084] Conversely, if the bearing capacity is reduced by too much, it will result in an excessive loss of the effective bearing area of ​​the foundation bed: even with the pre-compensation of the self-weight of the stones in the riprap pipe 2, the actual bearing capacity of the foundation bed still cannot meet the design requirements of the gravity wharf; at the same time, the later settlement is large, which is significantly more than the settlement of the traditional fully paved foundation bed, and is prone to safety hazards such as cracking of the wharf structure and displacement of caissons.

[0085] Therefore, a reasonable range is pre-defined. It represents the optimal range that balances load-bearing capacity compliance, no material overlap during construction, and controllable costs: it meets the lower limit. To avoid material waste and uneven settlement caused by excessively narrow furrows (42), and also through the upper limit... This approach ensures that the bearing capacity and settlement performance of the subgrade meet design requirements, while controlling the amount of stone used per vessel berth within an economically reasonable range (saving costs compared to stacking). This range setting fully complies with the design principles of technical feasibility and economic rationality in port engineering, enabling the technical solution in this embodiment to balance practicality and economy, and resolve the core contradiction in trench subgrade construction under harsh sea conditions.

[0086] In step S2, when laying the continuous ridge 41, the distance between the bottom of the riprap pipe 2 and the top of the ridge 41 is 0.3–0.8 m. (See appendix) Figure 3 This is a schematic diagram showing the height of the riprap 2 when laying the continuous ridge 41 in this embodiment. The value is 0.3 to 0.8m. The bottom of the stone-throwing pipe 2 is limited to 0.3 to 0.8m from the top of the ridge body 42. This can avoid the deviation of stone accumulation caused by the distance being too close, and prevent the stones from falling off due to the distance being too far. This ensures the flatness and continuity of the ridge body 41 and improves the accuracy of the base bed formation.

[0087] In step S2, when laying the continuous ridge 41, the height of the stones inside the riprap 2 is maintained at the designed leveling thickness. The height of the stones in the riprap 2 is 8.0 to 18.0 times T, so as to pre-compact the ridge body 41 by the self-weight of the stones. Pre-compaction by the self-weight of the stones is achieved through the height of the stones in the riprap pipe 2 (8.0 to 18.0 times T), which can promote the compaction of the stones in advance and generate moderate compression, reducing the problem of delayed settlement of the subgrade in the later stage, reducing the amount of leveling work after the caisson installation, and indirectly reducing rework costs. In this embodiment, the height of the stones in the riprap pipe 2 is H = 18T = 18 × 0.5 = 9m.

[0088] The height H of the stones inside the riprap pipe 2 is set because of the reduced bearing capacity of the subgrade caused by the aforementioned calculation of the furrow 42. and Theoretically, its settlement would be higher than that of a traditional fully paved subgrade. To verify this, a simultaneous onshore test was conducted, using a leveled subgrade layer (average thickness 50cm) consistent with the test results, simulating the pre-compression scenario of the stones within the riprap pipe 2: when the stone height inside the pipe was 6m (bulk density 1.7t / m³, generating pressure 0.15MPa), the subgrade compression reached 2cm; when the stone height was 9m (same density, same pressure), the compression reached 3cm, a 10% increase compared to the uncompressed condition. This pre-compression effect effectively offset the additional settlement risk caused by the furrow 42.

[0089] In step S4, during the acceptance inspection of the gravity-type wharf foundation 4, the distance between the bottom of the riprap pipe 2 and the top of the ridge 41 is 0.2–0.5 m. (See appendix) Figure 4 This is a schematic diagram showing the height of the riprap pipe 2 during the acceptance of the gravity-type wharf foundation 4 in this embodiment. The value is 0.2 to 0.5 m. By setting the detection distance, the detection accuracy of the underwater acoustic detection device 3 is improved, the size deviation and defects of the ridge 41 are more accurately identified, the reliability of the acceptance results is guaranteed, and an accurate basis is provided for subsequent construction.

[0090] In this embodiment, the hydraulic cylinder at the bottom of the sling pipe 2 has a telescopic range of 0.1 to 1.1 m, which can effectively resist the effects of large tidal range.

[0091] In step S2, the laying direction of the continuous ridge 41 forms an angle of 0° to 30° with the dominant direction of water flow or waves in the construction area to reduce the impact of water flow or waves on the ridge 41 and the riprap pipe 2. Reducing the direct impact of water flow or waves on the ridge 41 can reduce the risk of stone erosion and displacement on the ridge 41, reduce the load impact on the riprap pipe 2, ensure construction stability, and extend the service life of the equipment.

[0092] In step S2, when laying the continuous ridge 41, the moving speed of the stone-laying pipe 2 is 1.3 to 1.5 m / min. This ensures the uniformity of stone laying, avoids local material shortages due to excessive speed, and also takes into account construction efficiency, avoiding delays due to excessive slowness, thus achieving a balance between quality and schedule.

[0093] In step S4, during the acceptance inspection of the gravity-type wharf foundation 4, the moving speed of the riprap 2 is 2.0 m / min. With the underwater acoustic detection device 3 able to clearly identify the foundation structure, the acceptance process is accelerated, the acceptance time for a single area is shortened, and the overall construction efficiency is improved. In this embodiment, the underwater acoustic detection device 3 can be selected from underwater detection equipment based on acoustic principles, such as sonar or multibeam echo sounders.

[0094] In step S3, the laying is repeated until the ridge 41 and the furrow 42 together cover the entire area of ​​the gravity wharf foundation 4 to be constructed. See Appendix. Figure 5This is a schematic diagram of the plan layout for laying the ridge bed using the platform-type leveling vessel 1 in this embodiment. In the diagram, the left side is the bow and the right side is the stern, representing the bow and stern directions of the platform-type leveling vessel 1, clearly indicating the vessel's orientation during construction. In this embodiment, the length of the gravity-type wharf foundation 4 to be constructed is 43.05m, corresponding to the working area where the platform-type leveling vessel 1 lays the continuous ridges 41 along a serpentine path. The width of the gravity-type wharf foundation 4 to be constructed is 24.8m, reflecting the lateral coverage area of ​​the ridges 41. The multiple parallel lines within the yellow area represent the continuous ridges 41 laid by the riprap pipes 2. Adjacent ridges 41 are parallel to each other, distributed in a serpentine path, ultimately covering the entire foundation area. The length and width of the gravity-type wharf foundation 4 to be constructed are affected by the travel limits of the large and small trolleys of the platform-type leveling vessel 1; the maximum travel of the large trolley is 48m (under soft limit), and the maximum travel of the small trolley is 25m (under soft limit). Therefore, in this embodiment, the maximum travel length of the stone-throwing pipe 2 of the platform-type leveling vessel 1 in the bow-stern direction is 43.05m, and the maximum travel length of the stone-throwing pipe 2 in the port-to-port direction is 24.8m. (Based on the width of the ridge top...) If the ridges are laid out at a depth of 0.5m, then a maximum of 11 ridges can be laid on a single ship berth (i.e., 11 ridges are attached). Figure 5 The ridges marked 1#~11# (41) have a laying area of ​​1067㎡, which is about 1.2 container positions.

[0095] In this embodiment, the platform-type leveling vessel 1 can flexibly choose between a full-lift or full-floating process depending on the actual sea conditions. In areas with severe sea conditions, the full-lift process is used, where piles are driven into the vessel to lift it above the water surface. The rigid legs of the piles then prevent sea-related interference, ensuring the accuracy of the ridge laying. In areas with relatively calm sea conditions, the full-floating process is used, with the vessel anchored to eliminate the need for pile driving. This reduces the construction time per vessel position by 24% while still ensuring the accuracy of the ridge laying. Both processes are suitable for different scenarios, balancing stability and efficiency.

[0096] In the above illustrative embodiments, the gravity-type wharf foundation construction method under severe sea conditions based on a platform-type leveling vessel utilizes the lifting function of the platform-type leveling vessel to remove the hull from the influence of severe sea conditions, avoiding sea state interference, significantly improving the safety and stability of construction under severe sea conditions, reducing the risk of construction delays, and ensuring the quality of foundation construction. By optimizing the ratio of ridge and furrow dimensions, it avoids the waste of stone materials caused by stacking ridges and prevents the load-bearing hazards caused by excessively wide furrows, providing a flat and uniform stress foundation for the subsequent installation of wharf caissons, reducing the workload of caisson leveling, and indirectly improving the overall project efficiency.

[0097] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A method for constructing gravity-type wharf foundations under harsh sea conditions based on a platform-type leveling vessel, characterized in that, Includes the following steps: S1. Move the platform-type leveling vessel with lifting function to the construction area and position it, then lift it to remove the hull from the area affected by the severe sea conditions. S2. The riprap of the platform-type leveling vessel is laid in a serpentine path along the length of the gravity wharf foundation bed to be constructed, starting from the construction starting point, forming continuous ridges with adjacent ridges parallel to each other; wherein, the center-to-center distance between adjacent ridges is... The design leveling thickness of the gravity wharf foundation bed to be constructed. The width of the furrow top formed between adjacent ridges is 4.0 to 5.0 times that of adjacent ridges. For the design leveling thickness 0.9 to 1.1 times; S3. Repeat step S2 to lay the ridges until the ridges and furrows together cover the entire gravity wharf foundation area to be constructed. S4. The gravity-type wharf foundation is inspected along the extension direction of the embankment using the underwater acoustic detection device on the riprap pipe, and the center-to-center distance is verified by combining water depth scanning analysis. and furrow top width Meets the design leveling thickness in step S2 The proportions are well-defined, with no overlapping material and no obvious defects such as excessively wide furrows; S5. Calculate the reduction in subgrade bearing capacity caused by furrows, and determine whether the reduction is within a reasonable range to ensure that the subgrade bearing capacity and settlement performance meet the design requirements of gravity wharf.

2. The method for constructing gravity-type wharf foundations under harsh sea conditions based on a platform-type leveling vessel according to claim 1, characterized in that, In step S2, when laying continuous ridges, the distance between the bottom of the stone-throwing pipe and the top of the ridge is 0.3 to 0.8 m.

3. The method for constructing gravity-type wharf foundations under harsh sea conditions based on a platform-type leveling vessel according to claim 2, characterized in that, In step S2, when laying the continuous ridge, the height of the stones inside the riprap is maintained at the designed leveling thickness. The weight of the stone is 8.0 to 18.0 times that of the stone itself, so as to pre-compact the ridge with the weight of the stone.

4. The method for constructing gravity-type wharf foundations under harsh sea conditions based on a platform-type leveling vessel according to claim 1, characterized in that, In step S5, the preset reasonable range is: Calculate the percentage reduction in subgrade bearing capacity caused by furrowing. and ,in: And judge and To ensure that the reduction in the bearing capacity of the subgrade is within a certain range Within a reasonable range, meeting the design requirements of gravity-type wharves; among which, The percentage reduction is based on the maximum bearing capacity of the vertical projection of the furrow. The percentage reduction in the ultimate bearing capacity of furrows due to slope. The width of the furrow top of adjacent ridges. This represents the center-to-center distance between adjacent ridges.

5. The method for constructing gravity-type wharf foundations under harsh sea conditions based on a platform-type leveling vessel according to claim 1, characterized in that, In step S4, when the gravity-type wharf foundation is inspected, the distance between the bottom of the riprap pipe and the top of the ridge is 0.2 to 0.5 m.

6. The method for constructing gravity-type wharf foundations under harsh sea conditions based on a platform-type leveling vessel according to claim 1, characterized in that, In step S2, the laying direction of the continuous ridge is at an angle of 0° to 30° with the dominant direction of water flow or waves in the construction area, so as to reduce the impact of water flow or waves on the ridge and the riprap.

7. The method for constructing gravity-type wharf foundations under harsh sea conditions based on a platform-type leveling vessel according to claim 1, characterized in that, In step S2, when laying the continuous ridge, the moving speed of the stone-throwing pipe is 1.3 to 1.5 m / min.

8. The method for constructing gravity-type wharf foundations under harsh sea conditions based on a platform-type leveling vessel according to claim 1, characterized in that, In step S4, when the gravity-type wharf foundation is inspected, the moving speed of the riprap is 2.0 m / min.

9. The method for constructing gravity-type wharf foundations under harsh sea conditions based on a platform-type leveling vessel according to claim 1, characterized in that, In step S2, two pieces of stone are used as the stone material for laying the continuous ridge.

10. The method for constructing gravity-type wharf foundations under harsh sea conditions based on a platform-type leveling vessel according to claim 9, characterized in that, The particle size of the two stones is 8-15 cm.

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