Tower crane cofferdam method suitable for offshore tower group operation

Abstract

The invention relates to the field of tower crane cofferdams, and discloses a tower crane cofferdam method suitable for offshore tower group operation, which comprises the following steps: S1, mounting a tower crane embedded part and a cofferdam embedded part; s2, a stand column adjusting base is installed at the reserved connecting position of the cofferdam embedded part; s3, prefabricated stand columns are installed through the stand column adjusting bases, and the side walls of the water stop cofferdam are formed; s4, a flexible sealing gasket is arranged at the contact position of the edge of the cofferdam base and the top face of the bearing platform; s5, a flexible sealing gasket at the bottom of the cofferdam is evenly pressed on the top face of the bearing platform; s6, concrete is poured at the bottom of the cofferdam and a tower base side post-pouring area; and S7, after the tower crane cofferdams are installed, the large cofferdams outside the bearing platforms are dismantled, tower crane splicing is conducted, cofferdam formworks are recycled through dismantled bearing platform pouring formworks, installation and dismantling of the tower cranes and foundation construction can be independently conducted and do not interfere with each other, the limitation of a traditional large cofferdam on the construction period is broken through, and the turnover efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of tower crane cofferdams, and in particular to a tower crane cofferdam method suitable for offshore group tower operations. BACKGROUND

[0002] In the existing offshore group tower operation mode, a single large cofferdam is usually used to enclose the entire pile cap area. The biggest defect of this mode is the contradiction between its coordination and economy. On the one hand, the huge cofferdam structure leads to an excessively large waterproof area that needs to be controlled, increasing the construction difficulty and subsequent maintenance cost; on the other hand, due to the large difference in the use cycle and installation and removal time of each tower crane, the large cofferdam must take into account the latest removal of the tower crane, which unreasonably prolongs the use cycle of the cofferdam. This makes a large number of temporary engineering materials occupy for a long time, which seriously reduces the economic rationality of the cofferdam. In addition, after the pile cap is poured, a large number of formworks removed are often difficult to efficiently circulate and use, resulting in material waste and cost increase.

[0003] In this group tower operation mode requiring the setting of multiple tower crane cofferdams, the traditional sealing treatment relies on passive sealing measures (such as simple rubber pads), the effect of which is extremely susceptible to the unevenness of the pile cap surface, and since the pile cap surface conditions, installation stress and operation deviation of the bottom of each cofferdam are different, it is difficult to ensure that the sealing effect of each independent tower crane cofferdam can reach the consistent and high reliability standard, and the failure of any one interface can lead to the waterproof risk of the entire group tower operation system. SUMMARY

[0004] The present application aims to provide a tower crane cofferdam method suitable for offshore group tower operations to solve the above problems, and the specific technical solutions are as follows: A tower crane cofferdam method suitable for offshore group tower operations, comprising the following steps: S1, before pouring the pile cap, installing tower crane embedded parts and cofferdam embedded parts; S2, installing a column adjusting base at the reserved connection position of the cofferdam embedded part; S3, installing a prefabricated column through the column adjusting base, connecting at least two ring beams with the column through high-strength bolts, and installing a formwork on the inner side of the column and the ring beam to form the side wall of the water stop cofferdam, wherein the formwork is recycled using the removed pile cap pouring formwork; S4, setting a flexible sealing gasket at the position where the cofferdam base edge contacts the top surface of the pile cap, and setting pressure sensors at the bottom, middle and top of the cofferdam internal cavity; S5, by controlling the pressure difference between the water level inside the cofferdam and the outside seawater, and combining the pressure sensor feedback, the differential pressure is loaded in stages, the flexible sealing gasket at the bottom of the cofferdam is uniformly pressed on the top surface of the pile cap, the preliminary pre-pressing sealing and accurate centering of the bottom are realized; S6, after the preliminary pre-pressing sealing is completed, the cofferdam bottom and the tower seat side post-poured area are poured with concrete, and after the concrete curing is completed, the cofferdam is subjected to water spray test; S7, after the cofferdam of each tower crane is installed, the outer cofferdam of the pile cap is removed, and the tower crane is assembled.

[0005] As one of the improvements of the above technical solutions, the formwork is provided with a plurality of formworks, and the formworks are connected to each other by bolts, and a rubber waterstop is filled in the connecting gap between the formworks.

[0006] As one of the improvements of the above technical solutions, the column adjusting base is arranged above the pile cap embedded part, and a movement assembly for realizing three-dimensional positioning is arranged on the column adjusting base.

[0007] As one of the improvements of the above technical solutions, after the three-dimensional positioning of the adjusting base is completed, high-strength non-shrinkage grouting material is injected into the cavity of the base for filling and locking, and finally locked by a mechanical self-locking mechanism.

[0008] As one of the improvements of the above technical solutions, the differential pressure is loaded in stages by a controller driving a water pump to remove water in the cofferdam cavity, so that the external seawater pressure is greater than the internal water pressure, the differential pressure loading includes three stages of first loading, second loading and third loading, the first loading is used for centering, the second loading is used for pre-pressing, and the third loading is used for final pre-pressing or limit condition verification.

[0009] As one of the improvements of the above technical solutions, in the second loading and third loading stages, the pressure sensor feeds back the actual pressure data on the flexible sealing gasket to the controller to control the water pump pumping amount.

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

[0011] As one of the improvements of the above technical solutions, the tower seat side post-poured area is pre-buried with a backing type waterstop on the connecting interface with the original pile cap structure, and the post-poured area is poured with micro-expansion high-performance concrete.

[0012] As one of the improvements of the above technical solutions, the cofferdam is used to inject water into the internal cavity by a water pump before being removed, so that the net pressure of the cofferdam on the pile cap is close to zero or a small upward force is generated, and then the cofferdam is unlocked and lifted.

[0013] The cofferdam template is recycled by using the removed pile cap pouring template, which greatly reduces the demand for new templates, saves the procurement cost of temporary engineering materials, and the installation, disassembly and foundation construction of each tower crane can be carried out independently without interference, which breaks the limitation of traditional large cofferdams on construction period, greatly shortens the use time of the pile cap cofferdam, reduces the long-term occupation of materials, and improves the turnover efficiency. The high-precision linkage adjustment base of the column is introduced, and rapid, accurate and real-time adjustment of the cofferdam column in the X-Y plane, Z elevation and inclination is realized. This effectively compensates for the inevitable deviation of the pile cap embedded part construction, greatly improves the geometric accuracy and efficiency of the column installation, and avoids complex and time-consuming correction and rework on site. A dynamic pressure differential step loading mechanism is adopted, the external seawater pressure is used as the driving force, the active pre-pressing sealing of the flexible sealing gasket at the bottom of the cofferdam is realized, and the pre-pressing is monitored and uniformly controlled through the multi-point pressure sensor and the controller. This ensures that the sealing gasket is uniformly compressed, effectively overcomes the unevenness of the pile cap surface, improves the reliability of the sealing, and avoids the subsequent concrete construction risk caused by local leakage.

[0014] Additional aspects and advantages of the application will be described in part below, some will become apparent from the following description, or will be learned by practice of the application, of course, any product or method of the present application does not necessarily require all the advantages described above. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the drawings needed in the embodiment or prior art description will be briefly introduced below, and obviously, the drawings in the following description are only some embodiments of the application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0016] Figure 1 The construction flowchart of the application. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0018] Please refer to Figure 1 In the embodiments of the present application, a tower crane cofferdam method suitable for offshore group tower operation comprises the following steps. In the early stage, before pouring the pile cap, the tower crane embedded part and the cofferdam embedded part are accurately installed in place according to the design drawing; On the cofferdam embedded part on the top surface of the pile cap, a high-precision linkage adjustment base of the stand column is first installed; The prefabricated cofferdam stand column is hoisted and initially positioned through the adjustment base, then a ring beam (H-shaped steel or I-shaped steel can be used) is connected to the stand column through high-strength bolts, and the removed pile cap pouring formwork is used as the side wall formwork of the cofferdam and is installed on the inner side of the stand column and the ring beam; High-elastic rubber or water-swelling waterstop is pre-laid on the contact surface between the cofferdam base edge and the top surface of the pile cap as a flexible sealing gasket. A plurality of point pressure sensors (such as strain sensors) are installed along the bottom inside the cofferdam. After the cofferdam structure is erected, the water pump is started to slowly pump out the water in the cofferdam cavity. The control system receives the feedback of the pressure sensor to drive the water pump to load the pressure difference in stages (one-stage centering, two-stage pre-pressing, and three-stage final pressing). The external seawater is used to apply uniform net pressure to the cofferdam base to tightly press the flexible sealing gasket into the surface of the pile cap, and the stand column base is adjusted to realize accurate centering and reliable preliminary pre-pressing sealing.

[0019] After the pre-pressing sealing is checked, the bottom concrete inside the cofferdam and the post-poured concrete area of the tower base are poured. After the concrete curing is completed, a water injection test is performed to verify the final waterstop effect.

[0020] The above steps are repeated to complete the installation of all tower crane cofferdams and foundation construction, and finally the large cofferdam outside the pile cap is removed, so that the tower crane can be assembled.

[0021] The formworks are connected to each other through high-strength bolts, and rubber waterstop is filled in the connecting gap between the formworks. Specifically, before the formworks are recycled, they need to be cleaned and pretreated, and the edges of adjacent formworks are connected through high-strength bolts (such as M24) during assembly. Before the bolts are tightened, water-swelling rubber strips or high-elastic waterstop tapes are pre-embedded in the gap of the formwork edge contact surface as rubber waterstop to ensure that the connecting gap realizes double sealing (mechanical fastening + material waterstop) under the action of the bolt pretightening force.

[0022] The high-precision linkage adjustment base of the column is arranged on the pre-embedded part of the bearing platform, and at least three movement assemblies for realizing three-dimensional accurate positioning are arranged on the base structure.

[0023] Specifically, the linkage adjustment base body is a high-strength steel structure box, and the bottom is firmly connected to the pre-embedded part on the bearing platform through reserved bolts. Three independent and separately operated mechanisms are integrated in the base or at the interface between the base and the column, corresponding to three dimensions of horizontal (X-Y), vertical (Z) and inclination (α / β) respectively.

[0024] The three movement assemblies include a horizontal sliding adjustment block, a height adjustment screw rod and an inclination hinged ball head. The adjustment block is used for supporting the column and moving in the plane of the bearing platform; the screw rod is threadedly connected with the column base for vertical lifting; and the ball head is arranged between the column base and the adjustment base.

[0025] The horizontal sliding adjustment block: the column base is supported in the base through a ball guide rail or a low-friction PTFE sliding block, and jacks or horizontal bolts are arranged on both sides for driving the column base to move slightly in the X-Y direction (for example, ±50 mm) in the plane of the bearing platform.

[0026] The height adjustment screw rod: a high-precision hydraulic or mechanical screw jacking jack is arranged in the base, the screw rod top of which is threadedly connected with or jacks up the center of the column base, so as to realize the vertical (Z-axis) lifting adjustment of the column.

[0027] The inclination hinged ball head: the bottom of the column is designed in a spherical or universal hinge, allowing the column to swing at a small angle (for example, ±2°) when correcting the verticality, facilitating quick centering.

[0028] After the three-dimensional accurate positioning of the high-precision linkage adjustment base of the column is completed, high-strength non-shrinkage grouting material is injected into the cavity of the base for filling and locking, and finally locked in combination with the mechanical self-locking mechanism.

[0029] After the column reaches the final design position and accuracy through the linkage adjustment base, first, the mechanical wedge lock or high-strength lateral bolt in the base is started to provide immediate locking. Then, high-strength non-shrinkage grouting material (such as C60 grade) is injected through the grouting hole reserved in the base to fill the cavity of the base. After the grouting material hardens, the high-rigidity permanent connection between the column and the bearing platform is realized, providing equivalent structural reliability to welding.

[0030] The differential staged loading is to remove the water in the internal cavity of the cofferdam by driving the water pump through the controller, so that the external seawater pressure is greater than the internal water pressure. The staged loading includes three stages of primary loading (centering), secondary loading (pre-pressing) and tertiary loading (final pressing / testing).

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

[0032] Primary loading (centering): Pumping to a net pressure of the design minimum pre-tension (e.g. 10% P max ), achieving soft landing of the cofferdam, at which time the column base is adjusted.

[0033] Secondary loading (pre-pressurization): Continue pumping to a net pressure of the design median value (e.g. 70% P max ), activating the sealing gasket and achieving initial uniform compression.

[0034] Tertiary loading (final pressure / testing): Pumping to a net pressure of the design maximum value (e.g. 100% P max ) and maintaining it for a period of time to verify the ultimate sealing performance.

[0035] During the secondary and tertiary loading stages, pressure sensors provide real-time pressure data on the flexible sealing gasket to the controller to control the water pump's pumping capacity.

[0036] Pressure sensors (such as piezoelectric or strain sensors) are arranged on the support structure below the flexible sealing gasket. During the secondary and tertiary loading stages, 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 each point 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 the target value uniformly and stably.

[0037] During the pressure difference settlement process, the column high-precision linkage adjustment base remains in an adjustable state, and the base is used to make real-time fine adjustments to the elevation and perpendicularity of the cofferdam until the multi-point pressure sensor shows that the pressure distribution is uniform.

[0038] During the primary and secondary loading stages, the transverse sliding block and elevation adjustment screw of the column high-precision linkage adjustment base are in an unlocked or semi-locked state. When the multi-point pressure sensor feedback data is uneven, the construction personnel operate the screw of the base to make slight adjustments to the elevation or inclination of one side of the cofferdam, aiming to eliminate the uneven stress caused by the deviation of the pile cap or embedded parts while maintaining the pressure difference loading, so that the bottom sealing pressure is uniformly distributed on the entire interface.

[0039] The tower base side post-cast area is pre-embedded with a back-up type water stop at the connection interface with the original pile cap structure, and the post-cast area is cast with micro-expansion high-performance concrete.

[0040] During the original pile cap concrete pouring, PVC or rubber backing type waterstop is pre-installed at the interface position of the reserved post-pouring belt to form a second barrier for waterproofing. During the post-pouring belt concrete pouring, C40 or higher grade micro-expansion high-performance concrete (for example, mixed with expansion agent, with shrinkage compensation properties) is used to generate pre-stress on the new and old concrete interface by its micro-expansion performance, enhancing the interface density and impermeability.

[0041] Before the cofferdam is removed, water is pumped into the internal cavity to make the net pressure of the cofferdam on the pile cap close to zero or generate a small upward force, and then the cofferdam is unlocked and lifted.

[0042] When the tower foundation construction is completed and the cofferdam is ready to be removed, the water pump starts to slowly pump water into the internal cavity of the cofferdam. The amount of water pumped is controlled so that the water level inside the cofferdam gradually rises to the level of the external tidal water level or slightly higher than the external tidal water level, thereby using the internal water pressure to offset the net pressure of the external seawater on the cofferdam base, making the net pressure of the cofferdam on the pile cap close to zero or generating a small upward force. Subsequently, the operator releases the locking of the linkage adjustment base, easily lifting the cofferdam.

[0043] The cofferdam formwork is recycled using the removed pile cap pouring formwork, which greatly reduces the need for new formwork and saves the procurement cost of temporary engineering materials. The installation, disassembly and foundation construction of each tower can be carried out independently without interference, which breaks the traditional time limit of large cofferdams and greatly shortens the use time of the pile cap cofferdam, reduces the long-term occupation of materials, and improves the turnover efficiency. The introduction of high-precision linkage adjustment base for the column realizes rapid, accurate and real-time adjustment of the cofferdam column in the X-Y plane, Z elevation and inclination. This effectively compensates for the inevitable deviation of the pile cap pre-embedded part construction, greatly improves the geometric precision and efficiency of the column installation, and avoids complex and time-consuming correction and rework on site. Using a dynamic pressure differential step loading mechanism, the external seawater pressure is used as the driving force to achieve active pre-pressing sealing of the flexible sealing gasket at the bottom of the cofferdam. Through multi-point pressure sensors and controllers, closed-loop feedback is achieved to realize real-time monitoring and uniform control of the pre-pressing force. This ensures that the sealing gasket is uniformly compressed, effectively overcomes the unevenness of the pile cap surface, improves the reliability of the sealing, and avoids the risk of subsequent concrete construction due to local leakage.

[0044] In this document, reference to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of one another. As will be apparent to those of ordinary skill in the art, embodiments described herein can be combined with other embodiments.

[0045] It will be apparent to those skilled in the art that the application is not limited to the details of the above-exemplified embodiments and that the present application can be implemented in other particular forms without departing from the spirit or essential characteristics of the present application. The embodiments should therefore be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the above description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims

1. A tower cofferdam method suitable for offshore tower group operation, characterized in that, The method comprises the following steps: S1, before pouring the pile cap, install the tower crane embedded part and the cofferdam embedded part; S2, install the column adjusting base at the reserved connection position of the cofferdam embedded part; S3, install the prefabricated column through the column adjusting base, connect at least two layers of ring beams with the column through high-strength bolts, and install the formwork on the inner side of the column and the ring beam to form the side wall of the water stop cofferdam, wherein the formwork is recycled by using the removed pile cap pouring formwork; S4, set the flexible sealing gasket at the position where the cofferdam base edge is in contact with the top surface of the pile cap, and set the pressure sensor at the bottom, middle and top of the cofferdam internal cavity; S5, form the pressure difference between the internal water level of the cofferdam and the external seawater, and combine the pressure sensor feedback to perform graded loading on the pressure difference, so as to uniformly press the flexible sealing gasket at the bottom of the cofferdam on the top surface of the pile cap, realize the preliminary pre-pressing sealing and accurate centering of the bottom; S6, after the preliminary pre-pressing sealing is completed, pour concrete in the post-poured area of the cofferdam bottom and tower base, and after the concrete curing is completed, the cofferdam is subjected to water spray test; S7, after the cofferdam of each tower crane is installed, the outer cofferdam of the pile cap is removed, and the tower crane is assembled.

2. The tower cofferdam method for offshore tower group operation according to claim 1, characterized in that: The formwork is provided in plurality, and the plurality of formworks are connected with each other through bolts, and rubber waterstop is filled in the connecting gap between the formworks.

3. The tower cofferdam method for offshore tower group operation according to claim 1, characterized in that: The column adjusting base is arranged on the pile cap embedded part, and a movement assembly for realizing three-dimensional positioning is arranged on the column adjusting base.

4. The tower cofferdam method for offshore tower group operation according to claim 3, characterized in that: After the three-dimensional positioning of the adjusting base is completed, high-strength non-shrinkage grouting material is injected into the cavity of the adjusting base for filling and locking, and a mechanical self-locking mechanism is combined for final locking.

5. The tower cofferdam method for offshore tower group operation according to claim 1, characterized in that: The graded loading of the pressure difference is achieved by driving the water pump to remove water in the internal cavity of the cofferdam, so that the external seawater pressure is greater than the internal water pressure, and the graded loading comprises three stages of primary loading, secondary loading and tertiary loading, the primary loading is used for centering, the secondary loading is used for pre-pressing, and the tertiary loading is used for final pre-pressing loading or limit condition verification.

6. The tower cofferdam method for offshore tower group operation according to claim 5, characterized in that: In the secondary loading 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 amount of the water pump.

7. The tower cofferdam method for offshore tower group operation according to claim 1, characterized in that: In the pressure difference settlement process, the column high-precision linkage adjusting base remains in an adjustable state, the base is used for real-time fine adjustment of the elevation and perpendicularity of the cofferdam, and the pressure distribution is uniform until the pressure sensor shows that the pressure distribution is uniform.

8. The tower cofferdam method for offshore tower group operation according to claim 1, characterized in that: The tower base side post-poured area is pre-buried with a backing type waterstop at the connecting interface with the original pile cap structure, and the post-poured area is poured with micro-expansion high-performance concrete.

9. The tower cofferdam method for offshore tower group operation according to claim 1, characterized in that: Before the cofferdam is removed, the internal cavity of the cofferdam is filled with water by using the water pump, so that the net pressure of the cofferdam on the pile cap is close to zero or a small upward force is generated, and then the cofferdam is unlocked and lifted.

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