A guide pile shoe capable of reducing the hazard of stepping on footprints

Abstract

The present invention belongs to the technical field of movable platform installation in offshore engineering such as geotechnical, geological, and environmental projects, and provides a new type of guide pile shoe that can reduce the hazard of footprints. The new type of guide pile shoe is composed of any type of pile shoe and a guide plate; a guide plate is welded at the center below any existing type of pile shoe; the cross-sectional shape of the guide plate includes but is not limited to a cross, a straight line, a cross-shaped, etc. The size and thickness of the guide plate are determined according to the actual pile shoe size, and the anti-buckling requirements must be met. The new type of guide pile shoe of the present invention is suitable for all movable offshore platforms that require a pile shoe foundation, and can effectively reduce the lateral displacement of the platform and the horizontal force and bending moment acting on the pile legs when the entire platform is piled near the old pile pit, so that the pile insertion can proceed smoothly.

Description

Technical Field

[0001] The invention belongs to the technical field of movable platform installation in offshore engineering such as geotechnical, geological and environmental engineering, and relates to a novel guide pile shoe capable of reducing the hazard of stepping on footprints. Background Art

[0002] A self-elevating offshore platform is a common marine engineering machinery and a working base for implementing submarine oil and gas exploration and exploitation. A self-elevating offshore platform maintains the stability of the platform by inserting the pile shoe foundation into the seabed to a certain depth. After the operation is completed, the pile legs are pulled up and the entire platform is towed to the next well location for operation, and a pile pit will be formed at the original location. Commonly known as footprints. As the frequency of operations increases, self-elevating platforms are likely to perform secondary or multiple pile insertion and extraction operations (also known as "stepping on footprints") at similar or even the same location. During the process of piling near the footprints, the new platform may generate additional horizontal forces and bending moments acting on the pile shoes, which will cause the pile shoes to be offset, posing a hidden danger to the structural safety of the pile shoes, pile legs, and even the entire platform.

[0003] At present, the engineering measures taken to address the potential hazards caused by stepping on footprints include:

[0004] 1) New offshore platforms are piled far away from footprints, but the secondary pile-insertion distance of jack-up offshore platforms is determined by the cantilever beam between the drilling platform and the jack-up platform. This method is not applicable in actual engineering.

[0005] 2) The pile shoe used to form the pile pit is strictly used to insert piles above the old pile pit, but the selection of pile shoes for drilling platforms in actual projects is not flexible.

[0006] 3) Filling the old pile pit with soil that has similar properties to the surrounding seabed soil, but this method does not effectively solve the problem. During the footprinting process, obvious asymmetry in the soil movement pattern will occur, resulting in unacceptable forces and moments on the pile legs.

[0007] 4) Pile shoes are used to pre-insert piles near the expected pile insertion location, and the soil around the old pile pit (footprint) is squeezed into the pile pit. However, this method is limited by the gap between the drilling platform and the jack-up platform, and the operating space is small. On the other hand, this method can only be carried out under mild weather conditions, and the whole process takes a long time.

[0008] All of the above methods require pre-treatment on the seabed before stepping on the footprints, which costs extra time and money. Based on this, it is crucial to find a new type of guide pile shoe that does not require additional operations on the seabed but can effectively reduce the lateral displacement and unbearable horizontal forces and bending moments caused by stepping on the footprints. Summary of the invention

[0009] The embodiment of the present invention provides a new type of guide pile shoe to address the footprint problem. This type of pile shoe does not require pre-treatment on the seabed in advance, but can alleviate the lateral displacement problem caused by the footprint process, while effectively reducing the horizontal force and bending moment acting on the pile legs.

[0010] The technical solution of the present invention:

[0011] A new type of guide pile shoe that can reduce the hazard of stepping on footprints, the new type of guide pile shoe is composed of any type of pile shoe and a guide plate; a guide plate is welded at the center below any type of existing pile shoe; the cross-sectional shape of the guide plate includes but is not limited to a cross shape, a straight shape, a cross-shaped shape, etc. The size and thickness of the guide plate are determined according to the actual pile shoe size, and at the same time, the anti-buckling requirements must be met.

[0012] When the new guide pile shoe is inserted near the pile pit, the guide plate penetrates the seabed before the pile shoe body. Since the guide plate is a thin plate, the soil on both sides of the plate is evenly distributed during penetration, and no lateral displacement or additional horizontal force and bending moment will occur. When the pile shoe body begins to contact the seabed, the bottom of the guide plate has reached a position below the bottom of the pile pit. As the penetration depth increases, the pile shoe body tends to slide into the pile pit, but since the guide plate has penetrated a certain position on the seabed, the guide plate will prevent the entire new guide pile shoe from sliding into the pit, thereby reducing the lateral displacement and further reducing the bending moment acting on the pile leg due to the lateral displacement.

[0013] Beneficial effects of the invention: The device of the invention is suitable for all movable offshore platforms that require pile shoe foundations, and can effectively reduce the lateral displacement of the platform and the bending moment acting on the pile legs when the entire platform is piled near the old pile pit, so that the pile insertion can be carried out smoothly. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 There are three common types of offshore platform pile shoes;

[0015] Figure 1 (a) is Mod V "A" offshore platform pile shoe;

[0016] Figure 1 (b) 116C offshore platform pile shoe;

[0017] Figure 1 (c) is the pile shoe of the Haiyang Shiyou 944 platform.

[0018] Figure 2 It is a new type of guide pile shoe modified on the basis of the existing pile shoe, and the cross-sectional shape is a cross shape as an example;

[0019] Figure 2 (a) is a new Mod V "A" offshore platform pile shoe with guide plate;

[0020] Figure 2(b) is a new type of 116C offshore platform pile shoe with a guide plate;

[0021] Figure 2 (c) is the new offshore oil 944 platform pile shoe with guide plate.

[0022] Figure 3 It is a stress analysis of ordinary pile boots stepping on footprints.

[0023] Figure 4 It is a force analysis of the new type of pile boot with guide plate.

[0024] In the figure: 1 pile shoe body; 2 guide plate. DETAILED DESCRIPTION

[0025] The specific implementation of the present invention is described in detail below in combination with the technical scheme and the accompanying drawings.

[0026] Example

[0027] Figure 3 This is the stress analysis of the ordinary pile shoe footprint. The stress of the pile shoe body is as follows: Figure 3 (a) When the jack-up offshore platform is driving piles near the old pile pit, the soil on the left and right sides of the pile shoe body is unevenly distributed, and the soil flow mechanism is different. After the pile shoe body is subjected to the horizontal force directed into the pit, it deviates and slides toward the pile pit. At this time, the pile shoe body is tilted, and the uneven distribution of soil on both sides is aggravated. The horizontal force is further increased, causing the pile shoe body to tilt further, and the horizontal force and bending moment acting on the pile legs increase, which may eventually cause the pile legs to break, or even the entire platform to overturn, as shown in Figure 1. Figure 3 (b) as shown.

[0028] When the new guide pile shoe of this embodiment is inserted near the old pile pit, the guide plate penetrates into the pile pit before the pile shoe body. Since the cross-shaped guide plate is thin, the soil on both sides is uniformly distributed, so the forces on the left and right sides are balanced, and the entire new guide pile shoe will not be subjected to horizontal forces. With the increase of penetration depth, the pile shoe body begins to contact the pile pit, and at this time the guide plate has penetrated to a position below the pile pit. Even if the pile shoe body is subjected to a horizontal force directed into the pile pit, it will not slide into the pile pit. The existence of the guide plate reduces the horizontal slippage of the new guide pile shoe; in addition, since the guide plate ensures that the new guide pile shoe vertically penetrates the soil, the difference in soil on both sides of the pile shoe body gradually decreases with the increase of penetration depth, and the horizontal force received is much smaller than that of the simple pile shoe body penetration, which reduces the horizontal force and bending moment received by the new guide pile shoe to a certain extent.

[0029] In summary, this embodiment provides a new type of guide pile shoe, which can reduce the lateral displacement and increase in horizontal force that will occur when the pile shoe is inserted near the old pile pit, thereby ensuring the safety of the self-elevating offshore platform.

Claims

1. A guide pile shoe capable of reducing the hazard of stepping on footprints, characterized in that: The guide pile shoe is composed of any type of pile shoe and a guide plate; the guide plate is welded at the center below any type of existing pile shoe; the size and thickness of the guide plate are determined according to the actual pile shoe size and must meet the anti-buckling requirements; The guide pile shoe is used for inserting piles in an old pile pit, and the guide plate penetrates into the old pile pit before the pile shoe body, and the guide plate penetrates to a position below the old pile pit so that the pile shoe body contacts the old pile pit; The cross-sectional area of ​​the guide plate is smaller than the bottom area of ​​the pile shoe body.

2. The guide pile shoe capable of reducing the hazard of stepping on footprints according to claim 1 is characterized in that: The cross-sectional shape of the guide plate is a cross, a straight line or a cross.

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