Tower crane cofferdam method suitable for offshore group tower operation

Abstract

The present application relates to the field of tower crane cofferdam, disclose a kind of tower crane cofferdam method suitable for offshore group tower operation, comprising the following steps: S1, install tower crane embedded part and cofferdam embedded part;S2, install column adjusting base on the reserved connection position of the cofferdam embedded part;S3, install prefabricated column by the column adjusting base, form the side wall of water-stop cofferdam;S4, flexible sealing washer is arranged in the cofferdam base edge and the contact position of top surface of pile cap;S5, the flexible sealing washer of cofferdam bottom is evenly pressed on the top surface of pile cap;S6, in cofferdam bottom and tower base side post-cast area pours concrete;S7, after installing each tower crane cofferdam, remove the outer cofferdam of pile cap, carry out tower crane assembly, cofferdam formwork uses recycled cofferdam pouring formwork of having removed pile cap, the installation, disassembly and foundation construction of each tower crane can be independently carried out, do not interfere with each other, which breaks the traditional cofferdam to the limit of construction period, improves turnover efficiency.

Description

Technical Field

[0001] This invention relates to the field of tower crane cofferdams, and more particularly to a tower crane cofferdam method applicable to offshore multi-tower operations. Background Technology

[0002] In existing offshore tower crane operation models, a single large cofferdam is typically used to enclose the entire pier area. The biggest drawback of this model lies in the contradiction between coordination and economy. On the one hand, the massive cofferdam structure results in an excessively large waterproof area to be controlled, increasing construction difficulty and subsequent maintenance costs. On the other hand, due to the significant differences in the service life and installation / dismantling times of each tower crane, the large cofferdam must accommodate the crane being dismantled last, unreasonably extending the cofferdam's service life. This leads to the long-term occupation of a large amount of temporary engineering materials, severely reducing the economic rationality of the cofferdam. Furthermore, after the pier is poured, the large amount of dismantled formwork is often difficult to reuse efficiently, resulting in material waste and increased costs.

[0003] In this multi-tower crane operation mode that requires the setting of multiple tower crane cofferdams, traditional sealing treatment relies on passive sealing measures (such as simple rubber gaskets). The effectiveness of these measures is easily affected by the unevenness of the bearing platform surface. Furthermore, since the surface condition of the bearing platform at the bottom of each cofferdam, the installation stress, and the operational deviations are all different, it is difficult to ensure that the sealing effect of each independent tower crane cofferdam can reach a consistent and highly reliable standard. The failure of any interface may lead to the waterproof risk of the entire multi-tower crane operation system. Summary of the Invention

[0004] The purpose of this invention is to provide a method for cofferdam construction of tower cranes suitable for offshore multi-tower operations to solve the above-mentioned problems. The specific technical solution is as follows: A method for cofferdam construction of tower cranes suitable for offshore multi-tower operations includes the following steps: S1. Before pouring the foundation, install the tower crane embedded parts and the cofferdam embedded parts; S2. Install column adjustment bases at the reserved connection positions of the pre-embedded parts of the cofferdam; S3. Install precast columns through the column adjustment base, connect at least two layers of ring beams to the columns with high-strength bolts, and install templates on the inner side of the columns and ring beams to form the side wall of the water-stop cofferdam, wherein the templates are recycled from the dismantled foundation casting templates. S4. A flexible sealing gasket is installed at the contact position between the edge of the cofferdam base and the top surface of the pier, and pressure sensors are installed at the bottom, middle and top of the internal cavity of the cofferdam. S5. By controlling the pressure difference between the water level inside the cofferdam and the external seawater, and combining the feedback from the pressure sensor, the pressure difference is applied in stages to uniformly press the flexible sealing gasket at the bottom of the cofferdam onto the top surface of the pier, thereby achieving preliminary pre-pressure sealing and precise alignment at the bottom. S6. After the initial pre-pressure sealing is completed, concrete is poured at the bottom of the cofferdam and in the post-cast area on the side of the tower base. After the concrete has cured, the cofferdam is subjected to a water spraying test. S7. After installing the cofferdams for each tower crane, dismantle the large cofferdam outside the pier and assemble the tower cranes.

[0005] As an improvement to the above technical solution, multiple templates are provided, and the multiple templates are connected to each other by bolts, and rubber waterstops are filled in the connection gaps between the templates.

[0006] As an improvement to the above technical solution, the column adjustment base is set on the embedded part of the pier, and the column adjustment base is provided with a motion component for realizing three-dimensional positioning.

[0007] As an improvement to the above technical solution, after the adjustment base is positioned in three dimensions, high-strength non-shrink grout is injected into the cavity of the base for filling and locking, and finally locked in combination with a mechanical self-locking mechanism.

[0008] As one of the improvements to the above technical solution, the differential pressure staged loading is achieved by driving a water pump through a controller to remove water from the internal cavity of the cofferdam, so that the external seawater pressure is greater than the internal water pressure. The staged loading includes three stages: primary loading, secondary loading and tertiary loading. The primary loading is used for centering, the secondary loading is used for pre-pressure, and the tertiary loading is used for final pre-pressure loading or extreme condition verification.

[0009] As an improvement to the above technical solution, during the secondary and tertiary loading stages, the pressure sensor feeds back the actual pressure data on the flexible sealing gasket to the controller to control the water pumping volume.

[0010] As one of the improvements to the above technical solution, during the differential pressure settlement process, the high-precision linkage adjustment base of the column remains in an adjustable state. The base is used to make real-time fine adjustments to the elevation and verticality of the cofferdam until the multi-point pressure sensor shows that the pressure distribution is uniform.

[0011] As one of the improvements to the above technical solution, a backing-type waterstop is pre-embedded in the connection interface between the post-cast area on the tower base side and the original foundation structure, and the post-cast area is poured with micro-expansion high-performance concrete.

[0012] As an improvement to the above technical solution, before the cofferdam is dismantled, water is pumped into the internal cavity to make the net pressure of the cofferdam on the pier close to zero or generate a slight buoyancy, and then the cofferdam is unlocked and lifted.

[0013] The beneficial effects of this invention are as follows: The cofferdam formwork uses the dismantled foundation casting formwork for recycling, which greatly reduces the need for purchasing new formwork and saves the procurement cost of temporary engineering materials. The installation, dismantling and foundation construction of each tower crane can be carried out independently without interference. This breaks the traditional limitations of large cofferdams on the construction period, greatly shortens the service life of foundation cofferdams, reduces the long-term occupation of materials, and improves turnover efficiency. The introduction of a high-precision linkage adjustment base for the cofferdam columns enables rapid, accurate, and real-time adjustment of the columns in the XY plane, Z elevation, and inclination angle. This effectively compensates for unavoidable deviations during the construction of the embedded parts in the pier cap, greatly improves the geometric accuracy and efficiency of the column installation, and avoids complex and time-consuming on-site corrections and rework. A dynamic differential pressure grading loading mechanism was adopted, using external seawater pressure as the driving force to achieve active pre-compression sealing of the flexible sealing gasket at the bottom of the cofferdam. Closed-loop feedback through multi-point pressure sensors and a controller enabled real-time monitoring and uniform control of the pre-compression. This ensured uniform compression of the sealing gasket, effectively overcoming the unevenness of the pier surface, improving the reliability of the seal, and avoiding the risks of subsequent concrete construction due to localized leakage.

[0014] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Of course, implementing any product or method of this application does not necessarily require achieving all of the advantages described above at the same time. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a construction flowchart of the present invention. Detailed Implementation

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Please see Figure 1 In this embodiment of the invention, a method for cofferdam construction of tower cranes suitable for offshore multi-tower operations includes the following steps: In the preliminary preparation, before the foundation is poured, the tower crane embedded parts and cofferdam embedded parts are precisely installed in place according to the design drawings; First, install the high-precision linkage adjustment base of the column on the cofferdam embedded parts on the top surface of the pier. The prefabricated cofferdam columns are hoisted and initially positioned by adjusting the base. Then, the ring beam (which can be made of H-beams or I-beams) is connected to the columns with high-strength bolts. The dismantled foundation casting formwork is used as the side wall formwork of the cofferdam and installed on the inside of the columns and ring beam. High-elasticity rubber or water-swellable sealing strips are pre-laid as flexible sealing gaskets at the contact surface between the edge of the cofferdam base and the top surface of the pier. Multiple pressure sensors (such as strain sensors) are installed at various points along the bottom inside the cofferdam. After the cofferdam structure is erected, the water pumps are started to slowly extract water from the internal cavities of the cofferdam. The control system receives feedback from the pressure sensor and drives the water pumps to apply pressure differential in stages (first stage for centering, second stage for pre-pressurization, and third stage for final pressurization). Using external seawater, a uniform net pressure is applied to the cofferdam base, pressing the flexible sealing gasket tightly into the surface of the foundation. At the same time, fine adjustments are made in conjunction with the column base to achieve precise centering and reliable initial pre-pressurization sealing.

[0019] After the pre-stress seal passes inspection, the bottom concrete inside the cofferdam and the post-cast concrete area on the side of the tower base are poured. After the concrete curing is completed, a water spray test is conducted to verify the final water-stopping effect.

[0020] Repeat the above steps to complete the installation of all tower crane cofferdams and foundation construction. Finally, dismantle the large cofferdam outside the pier cap, and the tower crane can be assembled.

[0021] The templates are connected to each other with high-strength bolts, and the gaps between the templates are filled with rubber waterstops. Specifically, the templates need to be cleaned and pre-treated before reuse. During assembly, the edges of adjacent templates are connected by high-strength bolts (such as M24). Before tightening the bolts, water-swellable rubber strips or high-elasticity waterstops are pre-embedded in the gaps of the contact surfaces of the template edges to ensure that the connection gaps are double-sealed (mechanical tightening + material waterstop) under the action of bolt pre-tightening force.

[0022] The high-precision linkage adjustment base of the column is set on the embedded part of the pier, and the base structure is equipped with at least three motion components for achieving three-dimensional precise positioning.

[0023] Specifically, the linkage adjustment base body is a high-strength steel structure box, and its bottom is firmly connected to the embedded parts on the support platform by reserved bolts. Inside the base or at the interface where it connects with the column, there are three independent, individually operable mechanisms, corresponding to the three dimensions of horizontal (XY), vertical (Z) and tilt angle (α / β).

[0024] The three motion components include: a lateral sliding adjustment block, which supports the column and moves within the platform plane; an elevation adjustment screw, which is threaded to the column base for vertical lifting; and an angle hinged ball joint, which is located between the column base and the adjustment base.

[0025] Lateral sliding adjustment block: The column base is supported in the base by ball guide rails or low friction PTFE sliders. Jacks or horizontal bolts are provided on both sides to drive the column base to move slightly in the XY direction (e.g. ±50mm) within the platform plane.

[0026] Elevation Adjustment Screw: A high-precision hydraulic or mechanical threaded lifting jack is installed inside the base. The top of the screw is threaded to the center of the column base to lift and adjust the vertical direction (Z-axis) of the column.

[0027] Tilt hinge ball head: The bottom of the column adopts a spherical or universal hinge design, which allows the column to swing at a small angle (e.g. ±2°) during verticality correction, facilitating quick centering.

[0028] After the high-precision linkage adjustment base of the column is accurately positioned in three dimensions, high-strength non-shrink grout is injected into the cavity of the base for filling and locking, and finally locked in combination with a mechanical self-locking mechanism.

[0029] After the column reaches its final designed position and accuracy through the linkage adjustment base, the mechanical wedge lock or high-strength lateral bolts and other mechanical self-locking mechanisms inside the base are activated to provide immediate locking. Subsequently, high-strength non-shrink grout (such as C60 grade) is injected through the grouting holes reserved in the base to fill the base cavity. After the grout hardens, a high-rigidity permanent connection between the column and the foundation is achieved, providing structural reliability comparable to welding.

[0030] Differential pressure grading loading involves using a controller to drive a water pump to remove water from the internal cavity of the cofferdam, making the external seawater pressure greater than the internal water pressure. The grading loading includes three stages: primary loading (centering), secondary loading (pre-pressurization), and tertiary loading (final pressurization / testing).

[0031] A PLC (Programmable Logic Controller) is used to drive a water pump to extract water from inside the cofferdam at a precisely controlled flow rate.

[0032] Level 1 loading (centering): Pump water until the net pressure is the design minimum preload (e.g., 10% P). max This allows for a soft landing of the cofferdam, at which point the column base is adjusted.

[0033] Secondary loading (pre-compression): Continue pumping until the net pressure reaches the design median (e.g., 70% P). max This activates the sealing gasket and achieves initial uniform compression.

[0034] Three-stage loading (final pressure / test): Pumping until the net pressure reaches the design maximum (e.g., 100% P). max (and maintain for a period of time to verify the ultimate sealing performance).

[0035] During the secondary and tertiary loading stages, the pressure sensor feeds back the actual pressure data on the flexible sealing gasket to the controller to control the water pump's pumping volume.

[0036] Pressure sensors (such as piezoelectric or strain sensors) are mounted on a support structure beneath the flexible sealing gasket. During the secondary and tertiary loading stages, the real-time pressure data collected by these sensors is transmitted to the PLC controller. If the pressure deviates from the target value or the pressure distribution at various points is uneven, the PLC system will automatically adjust the frequency or power of the water pump to correct the pressure difference in real time until the pressure at all monitoring points reaches a uniform and stable target value.

[0037] During differential pressure settlement, the high-precision linkage adjustment base of the column remains in an adjustable state. The base is used to fine-tune the elevation and verticality of the cofferdam in real time until the pressure distribution is uniform as shown by multiple pressure sensors.

[0038] During the first and second loading stages, the lateral sliding block and elevation adjusting screw of the high-precision linkage adjustment base of the column are in an unlocked or semi-locked state. When the feedback data from the multi-point pressure sensors are uneven, the construction personnel operate the screw of the base to make slight lifting or tilting adjustments on one side of the cofferdam. The purpose is to maintain the differential pressure loading while eliminating uneven stress caused by the deviation of the abutment or embedded parts, so that the bottom sealing pressure is evenly distributed across the entire interface.

[0039] The post-cast area on the side of the tower base has a backing waterstop embedded at the interface with the original foundation structure, and the post-cast area is poured with micro-expansion high-performance concrete.

[0040] During the pouring of the original foundation concrete, a PVC or rubber-backed waterstop is pre-installed at the interface of the reserved post-pouring strip to form a second waterproof barrier. When pouring the post-pouring strip concrete, C40 or higher grade micro-expansion high-performance concrete (e.g., with expansion agent added, which has shrinkage compensation characteristics) is used. Its micro-expansion properties generate pre-stress at the interface between the new and old concrete, enhancing the density and impermeability of the interface.

[0041] Before the cofferdam is dismantled, water is pumped into the internal cavity to make the net pressure of the cofferdam on the pier close to zero or generate a slight buoyancy, and then the pier is unlocked and lifted.

[0042] After the tower crane foundation construction was completed and preparations were made to dismantle the cofferdam, water pumps began slowly injecting water into the cofferdam's internal cavity. The water injection rate was controlled so that the water level inside the cofferdam gradually rose to be level with or slightly higher than the external tide level. This used the internal water pressure to counteract the net pressure of the external seawater on the cofferdam base, resulting in a net pressure of the cofferdam on the foundation approaching zero or generating a slight buoyancy. Subsequently, the operators released the locking mechanism of the linkage adjustment base and easily lifted the cofferdam.

[0043] The cofferdam formwork uses the dismantled foundation casting formwork for recycling, which greatly reduces the need for purchasing new formwork and saves the procurement cost of temporary engineering materials. The installation, dismantling and foundation construction of each tower crane can be carried out independently without interference. This breaks the traditional limitations of large cofferdams on the construction period, greatly shortens the service life of foundation cofferdams, reduces long-term material occupation, and improves turnover efficiency. The introduction of a high-precision linkage adjustment base for the cofferdam columns enables rapid, accurate, and real-time adjustment of the columns in the XY plane, Z elevation, and inclination angle. This effectively compensates for unavoidable deviations during the construction of the embedded parts in the pier cap, greatly improves the geometric accuracy and efficiency of the column installation, and avoids complex and time-consuming on-site corrections and rework. A dynamic differential pressure grading loading mechanism was adopted, using external seawater pressure as the driving force to achieve active pre-compression sealing of the flexible sealing gasket at the bottom of the cofferdam. Closed-loop feedback through multi-point pressure sensors and a controller enabled real-time monitoring and uniform control of the pre-compression. This ensured uniform compression of the sealing gasket, effectively overcoming the unevenness of the pier surface, improving the reliability of the seal, and avoiding the risks of subsequent concrete construction due to localized leakage.

[0044] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0045] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method for cofferdam construction of tower cranes suitable for offshore multi-tower operations, characterized in that, Includes the following steps: S1. Before pouring the foundation, install the tower crane embedded parts and the cofferdam embedded parts; S2. Install column adjustment bases at the reserved connection positions of the pre-embedded parts of the cofferdam; S3. Install precast columns through the column adjustment base, connect at least two layers of ring beams to the columns with high-strength bolts, and install templates on the inner side of the columns and ring beams to form the side wall of the water-stop cofferdam, wherein the templates are recycled from the dismantled foundation casting templates. S4. A flexible sealing gasket is installed at the contact position between the edge of the cofferdam base and the top surface of the pier, and pressure sensors are installed at the bottom, middle and top of the internal cavity of the cofferdam. S5. By controlling the pressure difference between the water level inside the cofferdam and the external seawater, and combining the feedback from the pressure sensor, the pressure difference is applied in stages to uniformly press the flexible sealing gasket at the bottom of the cofferdam onto the top surface of the pier, thereby achieving preliminary pre-pressure sealing and precise alignment at the bottom. S6. After the initial pre-pressure sealing is completed, concrete is poured at the bottom of the cofferdam and in the post-cast area on the side of the tower base. After the concrete has cured, the cofferdam is subjected to a water spraying test. S7. After installing the cofferdams for each tower crane, dismantle the large cofferdam outside the pier cap and assemble the tower cranes. The column adjustment base is set on the embedded part of the support platform, and the column adjustment base is provided with a motion component for realizing three-dimensional positioning; During the graded loading process, the high-precision linkage column adjustment base of the column remains in an adjustable state. The column adjustment base is used to fine-tune the elevation and verticality of the cofferdam in real time until the pressure sensor shows that the pressure distribution is uniform. The graded loading is achieved by using a controller to drive a water pump to remove water from the internal cavity of the cofferdam, making the external seawater pressure greater than the internal water pressure. The graded loading includes three stages: primary loading, secondary loading, and tertiary loading. The primary loading is used for centering, the secondary loading is used for pre-stressing, and the tertiary loading is used for final pre-stressing or extreme condition verification.

2. The tower crane cofferdam method for offshore multi-tower operations according to claim 1, characterized in that: Multiple templates are provided, and the multiple templates are connected to each other by bolts, and the connection gaps between the templates are filled with rubber waterstops.

3. The method for cofferdam construction of tower cranes suitable for offshore multi-tower operations according to claim 1, characterized in that: After the column adjustment base is positioned in three dimensions, high-strength non-shrink grout is injected into the cavity of the base for filling and locking, and finally locked in combination with a mechanical self-locking mechanism.

4. The tower crane cofferdam method for offshore multi-tower operations according to claim 1, characterized in that: During the secondary and tertiary loading stages, the pressure sensor feeds back the actual pressure data on the flexible sealing gasket to the controller to control the water pump's pumping volume.

5. A method for cofferdam construction of tower cranes suitable for offshore multi-tower operations according to claim 1, characterized in that: The post-cast area on the side of the tower base has a backing waterstop embedded at the interface with the original foundation structure, and the post-cast area is cast with micro-expansion high-performance concrete.

6. A method for cofferdam construction of tower cranes suitable for offshore multi-tower operations according to claim 1, characterized in that: Before the cofferdam was dismantled, water was pumped into the internal cavity to make the net pressure of the cofferdam on the pier close to zero or generate a slight buoyancy, and then the cofferdam was unlocked and lifted.

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