Method of installing a pile by means of a pile guide

Abstract

In a method of installing a pile in the sea bottom by means of a pile guide which has a frame and at least an upper and a lower pair of cooperating guide members, wherein the upper pair and the lower pair are located at a distance from each other in vertical direction. Each pair of guide members comprises a passive guide member and an active guide member. The passive guide members are moved to respective fixed initial guiding positions with respect to the frame and the active guide members are moved to the pile until the passive and the active guide members engage the pile, after which the pile is hold between the upper pair of guide members and between the lower pair of guide members during driving the pile into the sea bottom, during which the actual forces between the pile and the respective guide members are determined.

Claims

1. A method of installing a pile in the sea bottom by means of a pile guide having a frame and at least an upper and a lower pair of cooperating guide members, wherein the upper pair and the lower pair are located at a distance from each other in a vertical direction, wherein each pair of guide members comprises a passive guide member and an active guide member, the method comprising: moving each of the passive guide members and the active guide members towards the pile (P) after placing the pile between each of the pairs of guide members, wherein the passive guide members are moved to respective fixed initial guiding positions with respect to the frame and the active guide members are moved to the pile until the passive and the active guide members engage the pile; driving the pile into the sea bottom while holding the pile between the upper pair of guide members and between the lower pair of guide members; measuring actual forces between the pile and the respective guide members during driving the pile into the sea bottom; moving the active guide member of a first of the pairs of guide members in a direction away from the pile without moving the passive guide member of the first pair relative to the pile when the actual forces at both the passive and active guide member of the first pair of guide members increase during driving the pile into the sea bottom; and moving the passive guide member of the first pair in a direction away from the pile if the actual force at the passive guide member of the first pair remains above a certain level without an increase of the actual force at the active member of the first pair during driving the pile into the sea bottom.

2. The method according to claim 1, wherein the guide members are operated hydraulically.

3. The method according to claim 1, wherein locations where resultant forces of the guide members engage the pile lie in a common plane.

4. The method according to claim 1, wherein the passive guide members of both pairs of guide members are located at the same side of the centerline of the pile.

5. The method according to claim 1, wherein the pair of upper guide members form a first pair of upper guide members, wherein a second, similar pair of upper guide members are located in a plane perpendicular to the common plane, and wherein the pair of lower guide members form a first pair of lower guide members, wherein a second, similar pair of lower guide members are located in a plane perpendicular to the common plane.

6. The method according to claim 1, wherein after placing the pile between each of the pairs of guide members, first the passive guide members are moved to respective fixed initial guiding positions with respect to the frame and subsequently the active guide members are moved to the pile until the passive and the active guide members engage the pile.

7. A method of installing a pile in the sea bottom by means of a pile guide having a frame and at least an upper and a lower pair of cooperating guide members, wherein the upper pair and the lower pair are located at a distance from each other in a vertical direction, wherein each pair of guide members comprises a passive guide member and an active guide member, the method comprising: moving each of the passive guide members and the active guide members towards the pile (P) after placing the pile between each of the pairs of guide members, wherein the passive guide members are moved to respective fixed initial guiding positions with respect to the frame and the active guide members are moved to the pile until the passive and the active guide members engage the pile; driving the pile into the sea bottom while holding the pile between the upper pair of guide members and between the lower pair of guide members; measuring actual forces between the pile and the respective guide members during driving the pile into the sea bottom; and locking at least two of the guide members in their positions relative to the pile during driving the pile into the sea bottom if the actual force at one of the guide members of the upper pair and an opposite actual force at one of the guide members of the lower pair both increase and the actual forces at the remaining guide members do not increase.

8. The method according to claim 7, wherein the guide members are operated hydraulically.

9. The method according to claim 7, wherein locations where resultant forces of the guide members engage the pile lie in a common plane.

10. The method according to claim 7, wherein the passive guide members of both pairs of guide members are located at the same side of the centerline of the pile.

11. The method according to claim 7, wherein the pair of upper guide members form a first pair of upper guide members, wherein a second, similar pair of upper guide members are located in a plane perpendicular to the common plane, and wherein the pair of lower guide members form a first pair of lower guide members, wherein a second, similar pair of lower guide members are located in a plane perpendicular to the common plane.

12. The method according to claim 7, wherein after placing the pile between each of the pairs of guide members, first the passive guide members are moved to respective fixed initial guiding positions with respect to the frame and subsequently the active guide members are moved to the pile until the passive and the active guide members engage the pile.

13. A method of installing a pile in the sea bottom by means of a pile guide having a frame and at least an upper and a lower pair of cooperating guide members, wherein the upper pair and the lower pair are located at a distance from each other in a vertical direction, wherein each pair of guide members comprises a passive guide member and an active guide member, the method comprising: moving each of the passive guide members and the active guide members towards the pile (P) after placing the pile between each of the pairs of guide members, wherein the passive guide members are moved to respective fixed initial guiding positions with respect to the frame and the active guide members are moved to the pile until the passive and the active guide members engage the pile; driving the pile into the sea bottom while holding the pile between the upper pair of guide members and between the lower pair of guide members; measuring actual forces between the pile and the respective guide members during driving the pile into the sea bottom; moving the active guide member of a first of the pairs of guide members in the direction of the pile when the actual force at the active guide member of the first pair decreases during driving the pile into the sea bottom; moving the active guide member of the first pair in the direction of the pile when the actual force at the passive guide member of the first pair decreases during driving the pile into the sea bottom; and moving the passive guide member of the first pair in the direction of the pile when the actual force at the passive guide member of the first pair remains below a predetermined level after moving the active guide member of the first pair in the direction of the pile.

14. The method according to claim 13, wherein the guide members are operated hydraulically.

15. The method according to claim 13, wherein locations where resultant forces of the guide members engage the pile lie in a common plane.

16. The method according to claim 13, wherein the passive guide members of both pairs of guide members are located at the same side of the centerline of the pile.

17. The method according to claim 13, wherein the pair of upper guide members form a first pair of upper guide members, wherein a second, similar pair of upper guide members are located in a plane perpendicular to the common plane, and wherein the pair of lower guide members form a first pair of lower guide members, wherein a second, similar pair of lower guide members are located in a plane perpendicular to the common plane.

18. The method according to claim 13, wherein after placing the pile between each of the pairs of guide members, first the passive guide members are moved to respective fixed initial guiding positions with respect to the frame and subsequently the active guide members are moved to the pile until the passive and the active guide members engage the pile.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will hereafter be elucidated with reference to schematic drawings showing an embodiment of the invention by way of example.

(2) FIG. 1 is a cross-sectional view of a pile guide for illustrating an embodiment of the method of installing a pile.

(3) FIG. 2 is a cross-sectional view of the pile guide of FIG. 1 along line II-II in FIG. 1.

DETAILED DESCRIPTION

(4) FIG. 1 shows a pile guide 1 which is suitable for guiding a pile P during submerged pile-driving. Under offshore operating conditions the pile guide 1 is placed on the sea bottom and a pile P which has to be inserted into the sea bottom by means of hammering is guided by the pile guide 1 during pile-driving. The embodiment of the pile guide 1 as shown in FIG. 1 is a simplified representation. In reality the pile guide 1 may be part of a construction which has feet for stable positioning and levelling the pile guide 1 on the sea bottom. The pile guide 1 may also be provided with a lifting element for lifting the pile guide 1. A surface vessel (not shown) having a hoist crane can position and lower the pile guide 1 onto the sea bottom before driving a pile and lift it after pile-driving.

(5) The embodiment of the pile guide 1 as shown in FIG. 1 comprises a frame in the form of a cylindrical guide sleeve 2 which envelopes a passage 3 for receiving the pile P. The guide sleeve 2 has a circular cross-section. The pile guide 1 is provided with eight guide members 4, 7, each having a roller 5 which can roll along the pile P during inserting the pile P into the sea bottom. The guide members 4, 7 are located at two parallel horizontal planes extending perpendicularly to a centerline 6 of the guide sleeve 2. In each of the planes four guide members 4 are disposed at equiangular distance from each other about the centerline 6, which is shown in cross-section of the pile guide 1 in FIG. 2. In this case the centerline 6 coincides with the centerline of the pile P.

(6) Each of the guide members 4, 7 is moveable with respect to the pile P and the guide sleeve 2 between a guiding position and a releasing position. Each guide member 4, 7 can be moved by means of a hydraulic cylinder (two of which are schematically illustrated in FIG. 2 at 9 and 10). In the embodiment as shown in FIG. 1 the guide member 4, 7 is moveable in radial direction to and from the centerline 6. The corresponding hydraulic cylinders 9, 10 extend in radial direction with respect to the centerline 6. FIG. 1 shows the guide members 4, 7 in their guiding positions, in which the rollers 5 project into the passage 3 and contact the pile P. When the guide members 4, 7 are in their releasing positions (FIG. 2) they are moved radially away from the centerline 6 by the hydraulic cylinders 9, 10 such that the pile P is loose from the guide members 4, 7 and the pile guide 1 can be removed from the pile P after installing the pile P. The guide members 4, 7 are also in their releasing positions before receiving the pile P in the passage 3 in order to facilitate inserting the pile P into the passage 3 before pile-driving.

(7) The guide members 4, 7 of the embodiment as shown in FIG. 1 form four pairs of opposite guide members 4a, 4b, and 7a, 7b, as illustrated in FIG. 2. Each of the horizontal planes in which four guide members 4 are present has two pairs of passive and active guide members 4a, 7a, 4b, 7b. As seen in vertical cross-section, as shown in FIG. 1, the pile guide 1 is provided with an upper pair 4a, 4b and a lower pair 7a, 7b of cooperating hydraulically operated guide members 4, 7 which contact and guide the pile P. The upper and lower pair of guide members 4, 7 are located at a distance from each other in vertical direction. The guide members 4a and 4b of the upper pair face each other at least in their guiding positions, and the guide members 7a and 7b of the upper pair face each other at least in their guiding positions. In their releasing positions the guide members 4, 7 are located at a larger distance from each other than in their guiding positions. Each pair of opposite guide members 4, 7 comprise a passive guide member 4a, 7a and an active guide member 4b, 7b. The passive guide members 4a, 7a have fixed guiding positions (represented by dashed lines 8a) with respect to the guide sleeve 2, which means that upon activating the corresponding hydraulic cylinders 9 the passive guide members 4a, 7a move to respective fixed locations with respect to the guide sleeve 2. The fixed guiding position corresponds with the maximum extension of a piston of the hydraulic cylinder 9, for example.

(8) The active guide member 4b, 7b has a flexible guiding position (represented by spacing between dashed lines 8b). This means that its position is adjustable by controlling the hydraulic cylinder 10. For example, if a pile P has a slightly different diameter the passive guide member 4a, 7a of a pair of guide members will still be at its fixed guiding position whereas the guiding position of the active guide member 4b, 7b will be adapted to the actual different diameter such that the pile P is not deformed by a too high local pressure or such that no gap will arise between the rollers 5 of the opposite guide members 4, 7 and the pile P. The presence of the passive guide member 4a, 7a provides a fast preparation for pile-driving since it can be moved to its initial fixed guiding position without a complicated hydraulic control. The guiding position of the active guide member 4b, 7b is controlled by actual hydraulic pressure in the corresponding hydraulic cylinder 8b. In practice, the hydraulic cylinder 9 for moving the passive guide member 4a, 7a can be operated at a higher pressure than the hydraulic cylinder 10 for moving the active guide member 4b, 7b.

(9) Both hydraulic cylinders are connected to respective accumulators (not shown) for relieving the guide members 4, 7 above a predetermined pressure. The accumulators prevent over pressure or overload of the pile guide 1 and the pile P in case of guiding a pile P which has a deviating diameter due to fabrication inaccuracy. For example, if the pile shape and diameter varies along its length, during pile-driving these variations must pass the rollers 5. When a larger diameter section of pile P, for example a weld bead, ovality or the like, passes, the rollers 5 must be moved outwardly with respect to each other. This is allowed by the accumulators. Basically, the majority of such a movement will be done by the accumulator cooperating with the active guide member 4b, 7b, but in case of an increase in pile diameter at the passive guide member 4a, 7a the accumulator cooperating with the passive guide member 4a, 7a may operate. It is noted that the accumulators can safeguard the guide members 4, 7 including the rollers 5 as well as the pile P. Since the contact stresses between the pile P and the rollers 5 are high, in practice the number of the rollers 5 and their diameter will be selected such that the risk of damage is minimized. The accumulators may be omitted in case of fast response times of the hydraulic cylinders. Nevertheless, in practice accumulators may still be applied from point of view of safety.

(10) Under operating conditions, before pile-driving, the eight guide members 4, 7 are retracted towards the wall of the guide sleeve 2 and a pile P is lowered by means of a hoist crane and inserted into the passage 3 of the guide sleeve 2 just above the sea bottom. The passive guide members 4a, 7a are moved to their fixed guiding positions and the pile P is clamped between the passive guide members 4a, 7a and the active guide members 4b, 7b by operating and controlling the cylinders for moving the active guide members 4b, 7b. The pile P is then lowered into the sea bottom and pile-driving is started. After installing the pile P the guide members 4, 7 are retracted and the pile guide 1 is lifted from the pile P.

(11) FIG. 1 illustrates that the pile P is held between the upper pair of guide members 4a, 4b and between the lower pair of guide members 7a, 7b in a direction parallel to an upwardly directed plane. In this case the resultant forces of the cooperating guide members 4a, 4b of the upper pair and lower pair 7a, 7b lie in a vertical plane in which the centerline of the pile P lies, as well. At the start of pile driving the passive guide members 4a, 7a of the upper and lower pair have a mainly fixed guiding position in radial direction of the centerline 6 of the guide sleeve 2 and it is intended to maintain this position during pile driving. As described above the diameter of the pile P may vary along its length and basically it is the active guide member 4b, 7b which has a variable guiding position in radial direction of the centerline 6 of the guide sleeve 2 in order to compensate for such variations.

(12) In the method the actual forces between the pile P and the respective guide members 4, 7 are measured. The actual forces provide feedback to a control system and on the basis of these signals the hydraulically controlled guide members 4, 7 can be moved to and from the pile P. The method responds to several situations.

(13) For example, if the actual force at the passive guide member 4a as well as at the active guide member 4b of the cooperating upper pair of guide members 4 exceed respective predetermined threshold levels, the active guide member 4b is moved in a direction away from the pile P in order to compensate for a portion of the pile P with increased diameter which passes the pair of upper guide members 4. Basically, the position of the passive guide member 4a with respect to the guide sleeve 2 remains unchanged. However, if the actual force at the passive guide member 4a of the upper pair 4 remains high in spite of moving the active guide member 4b in a direction away from the pile P and the actual force at the active member 4b does not increase, the passive guide member 4a is moved in a direction away from the pile P. Hence, in practice the method first attempts to compensate for a diameter increase by controlling the position of the active guide member 4b only, but also controls the position of the passive guide member 4a if required. A similar method of control occurs at the lower pair of guide members 7.

(14) If, for example, during pile driving the actual force at the passive guide member 4a of the upper pair of guide members 4 as well as the actual force at the active guide member 7b of the lower pair of guide members 7 increase whereas the actual force at the active guide member 4b of the upper pair of guide members 4 as well as the actual force at the passive guide member 7a of the lower pair of guide members 7 do not increase, all of the guide members 4, 7 remain in their actual position. When the opposite actual forces at diagonally located upper and lower guide members, in this example 4a and 7b, both increase, the pile P is typically leaning. A similar response of the guide members 4, 7 may be performed if the pile leans in a different direction.

(15) If, for example, during pile driving the actual force at the active guide member 4b of the upper pair of guide members 4 decreases, then the active guide member 4b of the upper pair of guide members 4 is moved in the direction of the pile P. If the actual force at the passive guide member 4a of the upper pair of guide members 4 decreases, then the active guide member 4b of the upper pair of guide members 4 is moved in the direction of the pile P, but if the actual force at the passive guide member 4a of the upper pair of guide members 4 remains below a predetermined level upon moving the active guide member 4b of the upper pair of guide members 4 in the direction of the pile P, then the passive guide member 4a of the upper pair of guide members 4 is moved in the direction of the pile P. This situation typically occurs in case of decreasing diameter of the pile P. A similar method of control occurs at the lower pair of guide members 7.

(16) From the foregoing, it will be clear that the invention provides a method for installing a pile in the sea bottom in a fast and accurate manner, whereas resistance between the pile and the guide members is minimized during pile driving.

(17) The invention is not limited to the embodiments shown in the drawings and described hereinbefore, which may be varied in different manners within the scope of the claims and their technical equivalents. For example, it is conceivable that the guide members are moveable by alternative drive means. Furthermore, the passive guide member and the active guide member of a pair of guide members may be out of line in their guiding positions but still facing each other. Moreover, the guide rollers may be replaced by slide pads or the like.