A horizontal static load test method and system for offshore single pile foundation

Abstract

The present invention discloses a method and system for horizontal static load test of offshore monopile foundation. In this scheme, the offshore monopile foundation is connected to a ship by an anchor cable, and the horizontal static load is applied to the offshore monopile foundation by the drag force generated when the ship is anchored. The scheme provided by the present invention can provide a reaction force for the horizontal static load test of the offshore monopile foundation, and at the same time overcomes the defect that the magnitude and direction of the test force change due to the shaking of the ship caused by tides, wind, waves, etc.

Description

Technical Field

[0001] The invention relates to a testing method, in particular to a horizontal static load testing method. Background Art

[0002] The horizontal static load test is the most direct and accurate method to determine the horizontal bearing capacity of the pile foundation. Through the static load test, the lateral foundation reaction of the foundation soil can be obtained, the reasonable calculation formula of the foundation soil resistance and the corresponding elastic foundation coefficient can be determined, and the horizontal bearing capacity of the test pile can be obtained.

[0003] The horizontal bearing capacity of offshore single piles, especially offshore super-large diameter single piles, is much greater than that of conventional diameter pile foundations. Similar to the vertical bearing capacity static load test, the horizontal force test also has the problem of loading method and loading tonnage. For the horizontal force test of conventional hydraulic structures such as dock pile foundations or offshore wind turbine foundation single piles, if the past reaction pile model is used and single piles are driven as reaction piles, the material cost of the reaction pile alone is easily several million yuan, and the cost of ships and machinery has not yet been considered, so the cost is very high.

[0004] It can be seen that providing a new reaction force mode and reducing the cost of pile testing are technical issues that urgently need to be solved in this field. Summary of the invention

[0005] In view of the problems existing in the existing offshore single pile horizontal force test technology, a new and low-cost offshore single pile horizontal force test solution is needed.

[0006] Therefore, the problem to be solved by the present invention is to provide a horizontal static load test method for an offshore single pile foundation and a horizontal static load test system for implementing the method.

[0007] In order to solve the above problems, the present invention provides a horizontal static load test method for an offshore single pile foundation, which uses an anchor cable to connect the offshore single pile foundation to a ship, and applies a horizontal static load to the offshore single pile foundation through the drag force generated when the ship is anchored.

[0008] Furthermore, the method also provides a tensioned and stable horizontal pulling force by cooperating with a valve-controlled asymmetric hydraulic cylinder electro-hydraulic servo system.

[0009] Furthermore, in the method, a corresponding loading level is first preset for the valve-controlled asymmetric hydraulic cylinder electro-hydraulic servo system according to actual conditions. When affected by the external environment, the valve-controlled asymmetric hydraulic cylinder electro-hydraulic servo system automatically restores the changed anchor force to a preset value in real time according to the preset loading level.

[0010] In order to solve the above problems, the present invention provides a horizontal static load test system for an offshore monopile foundation, comprising: a construction vessel and an anchor cable and an anchor arranged on the construction vessel, the anchor cable being connected to the offshore monopile foundation to be tested, and the anchor anchoring the construction vessel; the construction vessel applies a horizontal static load to the offshore monopile foundation through the dragging force generated when the anchor is raised.

[0011] Furthermore, the test system also includes an adjustable single pile loading protection device, which is sleeved on the offshore single pile foundation to be tested and connected to the anchor cable.

[0012] Furthermore, the adjustable single pile loading protection device includes a protection steel cylinder and a plurality of force bolts arranged on the protection steel cylinder, and the plurality of force bolts are correspondingly arranged on the cylinder wall of the protection steel cylinder to adjust the loading inner diameter in the protection steel cylinder.

[0013] Furthermore, the plurality of force bolts are divided into a plurality of groups and are arranged on the wall of the protective steel cylinder along the axial direction of the protective steel cylinder, and each group of force bolts is evenly distributed along the circumference of the protective steel cylinder.

[0014] Furthermore, a cushion block is provided at the top of the force bolt in contact with the pile body.

[0015] Furthermore, the test system also includes a valve-controlled asymmetric hydraulic cylinder electro-hydraulic servo system, which is arranged on the construction vessel and connected to the adjustment anchor cable.

[0016] Furthermore, the valve-controlled asymmetric hydraulic cylinder electro-hydraulic force servo system includes an upper computer, a lower computer, an electro-hydraulic servo valve, and an asymmetric hydraulic cylinder. The upper computer transmits commands to the lower computer, and the lower computer is used to control the electro-hydraulic servo valve and the asymmetric hydraulic cylinder. When a command is received from the main control computer, the electro-hydraulic servo valve is immediately controlled, and the electro-hydraulic servo valve is used to control the force in the electro-hydraulic servo force control system. The lower computer also performs data detection at the same time; the lower computer can receive the detection signal transmitted back by the lower computer in real time, process the data, and perform real-time monitoring.

[0017] The solution provided by the present invention can provide a reaction force for a horizontal static load test of an offshore single pile foundation, while overcoming the defect that the magnitude and direction of the test force change due to the shaking of the ship caused by tides, wind, waves, etc.

[0018] Furthermore, the test scheme provided by the present invention has a simple structure, is easy to implement, has a low implementation cost, and can perform loading tests on piles with different diameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0020] Figure 1It is a schematic diagram of a system for conducting a horizontal static load test of an offshore single pile foundation in an example of the present invention;

[0021] Figure 2 It is a working principle diagram of the valve-controlled asymmetric hydraulic cylinder electro-hydraulic servo system in an example of the present invention;

[0022] Figure 3 It is a schematic diagram of the structure of the adjustable single pile loading protection device in an example of the present invention. DETAILED DESCRIPTION

[0023] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below with reference to specific diagrams.

[0024] In view of the characteristics of the horizontal static load test of the offshore monopile foundation, this example adopts a new reaction force mode to effectively reduce the cost of the pile test. This solution mainly uses high-strength anchor cables to connect the offshore monopile foundation to the ship, and the drag force generated when the ship is anchored is used to apply a horizontal static load to the offshore monopile foundation.

[0025] See also Figure 1 , which is a schematic diagram of the composition of a horizontal static load test system for an offshore single pile foundation constructed based on the above principle in this example.

[0026] As can be seen from the figure, the offshore single pile foundation horizontal static load test system 100 provided in this example mainly includes five components: a construction vessel 110, an anchor 120, an anchor cable 130, a valve-controlled asymmetric hydraulic cylinder electro-hydraulic servo system 140 and an adjustable single pile loading protection device 150.

[0027] Among them, the anchor cable 130 is a high-strength anchor cable 130 used to connect the offshore monopile foundation 200 to be tested and the construction ship 110; at the same time, the anchor 120 is set on the construction ship 110 relative to the anchor cable 130, and is used to anchor the construction ship; and the construction ship 110 applies a horizontal static load to the offshore monopile foundation 200 through the drag force generated when raising the anchor.

[0028] There are no specific requirements for anchors and construction vessels in this scheme. It is only necessary to select ships and anchors of appropriate tonnage according to the load requirements of the single pile horizontal static load test.

[0029] The tensioning system of the anchor cable 130 is an important part of the horizontal static load test of the offshore monopile foundation. The load provided at each loading level must not deviate from the original position with the movement of the ship, and the influence of tides, wind, waves, etc. on the load value must be avoided. Therefore, the tensioning force of the anchor cable 130 needs to be automatically maintained and constant during the test, which is the guarantee for the test to be carried out.

[0030] To this end, in this embodiment, the tension of the anchor cable 130 is controlled and adjusted by a valve-controlled asymmetric hydraulic cylinder electro-hydraulic servo system 140 to provide a tensioned and stable horizontal pulling force for the offshore monopile foundation.

[0031] The servo control system consists of a main control computer and several single-chip microcomputers. The main control computer issues control instructions, and the single-chip microcomputer controls the servo valve and asymmetric hydraulic cylinder, thereby providing a tensioned and stable horizontal pulling force for the offshore single pile foundation.

[0032] The valve-controlled asymmetric hydraulic cylinder electro-hydraulic servo system 140 is arranged on the construction vessel 110 and controls the connected anchor cable 130 , thereby achieving control over the tensioning of the anchor cable 130 by cooperating with the construction vessel 110 .

[0033] The valve-controlled asymmetric hydraulic cylinder electro-hydraulic servo system 140 acts as a compensation device to cooperate with the ship to apply force.

[0034] See also Figure 2 , which shows the working principle diagram of the servo control system in this example. As can be seen from the figure, the entire system consists of a main control computer (host computer) 141 and several single-chip microcomputers (slave computers) 142. When the load level is reached, the main control computer (host computer) 141 directly issues a control command and transmits the command to the single-chip microcomputer through the serial port 143. The single-chip microcomputer 142 is used to control the servo valve and asymmetric hydraulic cylinder. When receiving the command from the main control computer, it immediately controls the electro-hydraulic servo valve, and the electro-hydraulic servo valve is used to control the force in the electro-hydraulic servo force control system. The single-chip microcomputer also performs data detection at the same time. The main control computer can receive the detection signal transmitted back by the single-chip microcomputer in real time, process the data, and perform real-time monitoring.

[0035] This servo control system is automatically controlled by the main control computer. Before implementation, a loading level is preset according to the actual situation. When affected by the external environment, the main control computer will automatically restore the changed anchor force to the preset value, thereby ensuring the stability of the tensioning force.

[0036] In the specific implementation, it is preferred to pre-set the command signal for the servo system. The command signal is the loading level required during loading. When the hull shakes due to tides, wind, waves, etc., causing the anchor force to change, the servo system can respond quickly and return to the original stable state (command signal) to operate, or under the action of the input command signal, it can return to the original equilibrium state after a short adjustment process, ensuring that the anchor tension is automatically maintained and constant during the test.

[0037] On this basis, in order to meet the needs of loading tests with different pile diameters, this example solution further adds an adjustable single pile loading protection device 105. The loading inner diameter of the adjustable single pile loading protection device 105 is adjustable, so that it is integrally mounted on the offshore single pile foundation 200 to be tested and connected to the anchor cable 130, so that the drag force generated when the ship is anchored can be applied to the offshore single pile foundation 200 to form a horizontal static load on the offshore single pile foundation 200.

[0038] See also Figure 3 The adjustable single pile loading protection device 150 is mainly composed of a protective steel cylinder 151 of a certain thickness and a plurality of force bolts 152 arranged thereon.

[0039] The inner diameter of the protective steel cylinder 151 is larger than the outer diameter of the common offshore monopile foundation 200. A plurality of force bolts 152 are threadedly arranged on the cylinder wall of the protective steel cylinder 151 in a certain manner, that is, each force bolt 152 can move radially along the offshore monopile foundation 200 by rotating, so that the loadable internal force in the protective steel cylinder 151 can be adjusted by the mutual cooperation of the plurality of force bolts 152.

[0040] On this basis, this example preferably divides the plurality of force bolts 152 into a plurality of groups and arranges them on the wall of the protective steel cylinder along the axial direction of the protective steel cylinder, and each group of force bolts is evenly distributed along the circumference of the protective steel cylinder.

[0041] As an example, 16 force bolts 152 are preferably used in the illustrated scheme. The 16 force bolts 152 are divided into two groups of 8 each. The two groups of force bolts 152 are correspondingly distributed on the outer wall of the protective steel cylinder 151 above and below. At the same time, the 8 force bolts 152 in each group are evenly arranged along the circumference of the protective steel cylinder 151.

[0042] The adjustable single pile loading protection device 150 thus constituted can form a corresponding loading inner diameter by rotating the force bolts 152, and the force bolts 152 cooperate with each other in the protection steel cylinder 151. Therefore, the loading inner diameter can be adjusted by rotating the bolts according to the different diameters of the actual test single pile.

[0043] At the same time, in this example, a steel plate pad 153 is arranged at the contact point between each force bolt 152 and the pile body to reduce stress concentration. The device can be applied to the loading requirements of different pile diameters, and avoids local buckling deformation caused by direct action between the pile and the anchor cable.

[0044] The horizontal static load test of the offshore monopile foundation thus formed adopts the slow-maintained load method when conducting the horizontal static load test on the offshore monopile foundation. The horizontal load is provided by the ship and the valve-controlled asymmetric hydraulic cylinder electro-hydraulic servo system. The slow-maintained load method here specifically loads the load in sections according to the test requirements, and each level of load is maintained unchanged for a period of time until the horizontal displacement reaches stability before the next level of loading is carried out.

[0045] When the set loading level is reached, the servo control system starts working immediately to ensure that the tension of the anchor cable is automatically maintained and constant during the test.

[0046] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A horizontal static load test method for an offshore single pile foundation, characterized in that: The offshore monopile foundation is connected to the ship by using an anchor cable, and the drag force generated when the ship is anchored provides a reaction force for the horizontal static load test of the offshore monopile foundation, thereby applying a horizontal static load to the offshore monopile foundation; the method also provides a tensioned and stable horizontal pulling force by cooperating with a valve-controlled asymmetric hydraulic cylinder electro-hydraulic servo system, and the load provided by the valve-controlled asymmetric hydraulic cylinder electro-hydraulic servo system at each level of loading does not deviate from the original position as the ship moves, and the tension of the anchor cable is automatically maintained and constant during the test. The valve-controlled asymmetric hydraulic cylinder electro-hydraulic servo system is arranged on the ship and controls the connected anchor cable, and acts as a compensation device to cooperate with the ship to control the tension of the anchor cable; the method In the method, the corresponding loading level is preset for the valve-controlled asymmetric hydraulic cylinder electro-hydraulic servo system according to the actual situation. The slow load maintenance method is first adopted. The ship and the valve-controlled asymmetric hydraulic cylinder electro-hydraulic servo system jointly provide the horizontal load. The load is loaded in sections according to the test requirements. Each level of load is maintained unchanged for a period of time until the horizontal displacement reaches stability before the next level of loading is carried out. When the set loading level is reached, the servo control system starts working immediately. When affected by the external environment, the valve-controlled asymmetric hydraulic cylinder electro-hydraulic servo system automatically restores the changing anchor force to the preset value in real time according to the preset loading level, ensuring that the anchor tensioning force is automatically maintained and constant during the test.

2. Offshore single pile foundation horizontal static load test system, characterized by: The test system comprises: a construction vessel, an anchor cable and an anchor arranged on the construction vessel, and a valve-controlled asymmetric hydraulic cylinder electro-hydraulic servo system, wherein the anchor cable is connected to the offshore monopile foundation to be tested, and the anchor anchors the construction vessel; the construction vessel applies a horizontal static load to the offshore monopile foundation through the drag force generated when the anchor is lifted; the valve-controlled asymmetric hydraulic cylinder electro-hydraulic servo system provides a tensioned and stable horizontal pulling force, and the load provided at each level of loading does not deviate from the original position as the vessel moves, and the tension of the anchor cable is automatically maintained and constant during the test; the valve-controlled asymmetric hydraulic cylinder electro-hydraulic servo system is arranged on the vessel, and controls the connected anchor cable, and acts as a compensation device to cooperate with the vessel to Control of anchor cable tensioning; firstly, preset the corresponding loading level for the valve-controlled asymmetric hydraulic cylinder electro-hydraulic servo system according to the actual situation, first adopt the slow load maintenance method, the ship and the valve-controlled asymmetric hydraulic cylinder electro-hydraulic servo system jointly provide the horizontal load, and the load is loaded in sections according to the test requirements, and each level of load is maintained unchanged for a period of time until the horizontal displacement reaches stability before the next level of loading is carried out; when the set loading level is reached, the servo control system starts working immediately, and when affected by the external environment, the valve-controlled asymmetric hydraulic cylinder electro-hydraulic servo system automatically restores the changing anchor cable force to the preset value in real time according to the preset loading level, ensuring that the anchor cable tensioning force is automatically maintained and constant during the test.

3. The offshore single pile foundation horizontal static load test system according to claim 2, characterized in that: The test system also includes an adjustable monopile loading protection device, which is sleeved on the offshore monopile foundation to be tested and connected to the anchor cable.

4. The offshore single pile foundation horizontal static load test system according to claim 3, characterized in that: The adjustable single pile loading protection device comprises a protection steel cylinder and a plurality of force bolts arranged on the protection steel cylinder. The plurality of force bolts are correspondingly arranged on the cylinder wall of the protection steel cylinder to adjust the loading inner diameter in the protection steel cylinder.

5. The offshore monopile foundation horizontal static load test system according to claim 4, characterized in that: The plurality of force bolts are divided into a plurality of groups and are arranged on the wall of the protective steel cylinder along the axial direction of the protective steel cylinder, and each group of force bolts is evenly distributed along the circumference of the protective steel cylinder.

6. The offshore monopile foundation horizontal static load test system according to claim 4, characterized in that: A cushion block is arranged at the top of the force bolt in contact with the pile body.

7. The offshore monopile foundation horizontal static load test system according to claim 2, characterized in that: The valve-controlled asymmetric hydraulic cylinder electro-hydraulic force servo system includes an upper computer, a lower computer, an electro-hydraulic servo valve, and an asymmetric hydraulic cylinder. The upper computer transmits commands to the lower computer, and the lower computer is used to control the electro-hydraulic servo valve and the asymmetric hydraulic cylinder. When a command is received from the main control computer, the electro-hydraulic servo valve is immediately controlled, and the electro-hydraulic servo valve is used to control the force in the electro-hydraulic servo force control system. The lower computer also performs data detection at the same time; the lower computer can receive the detection signal transmitted back by the lower computer in real time, process the data, and perform real-time monitoring.

Images