Vibro-hammer pile driver equipped with a method for determining whether the pile reaches the supporting layer and a pile construction support system.

Abstract

The present invention provides a vibro-hammer pile driver equipped with a pile construction support system and a pile bearing layer arrival determination method, which enables reliable installation of support piles, such as steel piles, into bearing layers investigated by N-values, and highly accurate determination of whether the tip of the support pile has reached the bearing layer assumed by the N-values. [Solution] A steel pile a is installed in the support layer assumed by the N value using a push-and-drive vibro-hammer pile driver 1, which includes a leader 5 erected at the installation position of the steel pile a, a vibro-hammer 7 mounted on the leader 5 so as to be movable up and down and to apply vibration to the steel pile a, and a pushing hydraulic cylinder 10 that pushes the steel pile a into the ground via the leader 5. The correlation between the value calculated by the determination formula P1 × P2 ÷ v from the pushing force P1 and pushing speed v of the pushing hydraulic cylinder 10 that pushes the steel pile a into the ground and the vibration force P2 of the vibro-hammer 7 that applies vibration to the steel pile a, and the N value, is used to estimate that the steel pile a has reached the support layer assumed by the N value.

Description

Technical Field

[0001] The present invention relates to a vibro hammer pile driver equipped with a pile support layer reaching determination method and a pile driving support system, which can reliably install a support pile such as a steel pile in a support layer estimated by the N value and can accurately estimate that the support layer has been reached.

Background Art

[0002] When constructing a support pile such as a steel pile, it is necessary to investigate in advance the support layer and its depth assumed at the time of design by the N value and construct so that the tip of the pile reaches the assumed support layer. The pile constructor is obliged to confirm that the tip of the pile has reached the assumed support layer.

[0003] Here, the N value is an index for obtaining the strength etc. of the support layer investigated by the standard penetration test (JIS A 1219), and is indicated by the number of blows required to penetrate a sampler (reference pile) into the ground to a predetermined depth by a drive hammer.

[0004] For example, when constructing a ready-made pile such as a steel pile by a vibro hammer, it is possible to confirm that the tip of the ready-made pile has reached the assumed support layer by pressing the ready-made pile into the depth indicated by the previously investigated N value.

[0005] Also, for example, Patent Document 1 discloses an invention of a vibro hammer construction machine for installing a pile in the ground while applying vibration by a vibro hammer, which has a construction support information calculation device that sequentially confirms the cumulative impact force calculated based on the vibration force and the number of blows of the vibro hammer obtained during construction and the depth of the pile, and determines the depth of the support layer in real time.

[0006] Furthermore, Patent Document 2 discloses a vibro-hammer pile driver that uses a leader equipped with a vibro-hammer for applying vibration to the pile and a hydraulic cylinder for pushing the pile into the ground via the leader to install the pile into a support layer assumed by the N-value, and includes a pile construction support system that determines whether or not the tip of the pile has reached the assumed support layer based on the correlation between the pushing force and pushing speed of the hydraulic cylinder for pushing, the excitation force of the vibro-hammer, and a previously investigated N-value. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Patent No. 5846592 [Patent Document 2] Japanese Patent Publication No. 2024-22181 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, while it is desirable to conduct the standard penetration test for each pile that is actually constructed, this is not practical due to the extremely large number of piles, etc. Therefore, the test is not conducted for each pile that is actually constructed, and as a result, the depth of the bearing layer indicated by the N value and the depth of the bearing layer where the pile is actually constructed do not match, which is a problem in terms of accuracy.

[0009] Furthermore, the vibro-hammer construction machine described in Patent Document 1 basically reduces the frictional resistance of the pile's surface by the forced vibration applied to the pile, and the pile does not penetrate into the ground and is not forcibly pushed in by the combined weight of the vibro-hammer and the pile exceeding the resistance force at the pile tip. Therefore, it takes time for the pile to reach the supporting layer, and work efficiency can be significantly reduced, especially in hard soil layers.

[0010] Furthermore, the vibro-hammer pile driver described in Patent Document 2 had the problem that it was not possible to accurately estimate whether the steel pile had reached the support layer assumed during the design phase based solely on construction data such as the pile driving force and driving speed obtained from the pile driver.

[0011] The present invention was made to solve the above problems, and aims to provide a vibro-hammer pile driver equipped with a pile support layer arrival determination method and pile construction support system that can reliably install support piles such as steel piles into the support layer assumed by the N value during the design phase, and can determine with high accuracy whether or not the pile has reached the support layer assumed by the N value. [Means for solving the problem]

[0012] The present invention relates to a pile construction method for determining whether a pile has reached a supporting layer, in which a pile is installed in a supporting layer assumed by an N value using a push-and-drive vibro-hammer pile driver equipped with a leader erected at the pile installation site, a vibro-hammer installed on the leader so as to be able to move up and down and to apply vibration to the pile, and a pushing hydraulic cylinder for pushing the pile into the ground via the leader, and is characterized in that the method estimates whether the pile has reached the supporting layer assumed by the N value based on the correlation between the value calculated by determination formula (1) from the pushing force P1 and pushing speed v of the pushing hydraulic cylinder and the excitation force P2 of the vibro-hammer, and the N value. P1 × P2 ÷ v ……(1)

[0013] Furthermore, the vibro-hammer pile driver used in the method for determining whether the pile has reached the supporting layer is preferably equipped with a pile construction support system that includes a storage unit for organizing and storing the values ​​of the pressing force P1, the pressing speed v, and the excitation force P2 as data.

[0014] Furthermore, a vibro-hammer pile driver equipped with a pile construction support system may include a calculation unit that calculates the pushing force P1 and pushing speed v of the pushing hydraulic cylinder, and the excitation force P2 of the vibro-hammer, based on the operating hydraulic pressure of the pushing hydraulic cylinder, the eccentricity of the eccentric weight provided in the vibro-hammer, and the penetration depth of the pile and the time it takes to reach the penetration depth.

[0015] Furthermore, the present invention relates to a pile construction method in which a pile is installed in a support layer assumed by the N value using a push-and-drive vibro-hammer pile driver equipped with a leader erected at the installation position, a vibro-hammer installed on the leader so as to be able to move up and down and to apply vibration to the pile, and a pushing hydraulic cylinder for pushing the pile into the ground via the leader, and is characterized in that the method estimates whether the pile has reached the support layer assumed by the N value based on the correlation between the value calculated by determination formula (2) from the pushing force P1 of the pushing hydraulic cylinder that pushes the pile into the ground and the excitation force P2 of the vibro-hammer that applies vibration to the pile, and the N value. P1 ÷ P2 ... (2)

[0016] While it is preferable to use formula (1) as a determination formula to estimate with high accuracy whether the pile has reached the expected bearing layer, depending on construction experience, construction results, etc., determination formula (2) may be used instead of formula (1).

[0017] Furthermore, the vibro-hammer pile driver used in the method for determining whether a pile has reached the supporting layer according to the present invention is preferably a vibro-hammer pile driver equipped with a pile construction support system that includes a storage unit for organizing and storing the values ​​of the pressing force P1 and the excitation force P2 as data.

[0018] Further, in the vibro hammer pile driver equipped with the pile driving support system of the present invention, from the hydraulic pressure of the operating oil of the pushing hydraulic cylinder, the amount of eccentricity of the eccentric weight provided in the vibro hammer, the penetration depth of the pile, and the arrival time when the penetration depth is reached, it is preferable to include an arithmetic unit that calculates the pushing force P1 of the pushing hydraulic cylinder and the vibration excitation force P2 of the vibro hammer.

Effects of the Invention

[0019] According to the present invention, by using two devices, namely, a vibro hammer and a pushing hydraulic cylinder provided in the pile driver, piles such as steel piles and sheet piles can be efficiently and reliably installed in the support layer assumed by the N value.

[0020] Further, from the pushing force P1 and the pushing speed v of the pushing hydraulic cylinder and the vibration excitation force P2 of the vibro hammer, or from the pushing force P1 and the vibration excitation force P2 of the vibro hammer, the support layer of the pile can be estimated with high accuracy from the correlation between the value calculated by the determination formula (1) or (2) and the N value investigated in advance.

Brief Description of the Drawings

[0021] [Figure 1] It is an embodiment of a vibro hammer pile driver equipped with the pile driving support system of the present invention, and is a side view in the basic posture. [Figure 2] It is the vibro hammer pile driver shown in FIG. 1, and is a side view in a state where the leader is at a position higher than the base machine. [Figure 3] It is an explanatory view of the vibro hammer provided in the vibro hammer pile driver of FIG. 1, where FIG. (a) is a front view and FIG. (b) is a side view. [Figure 4] FIG. (a) is a perspective view of the leader, and FIG. (b) is a perspective view of the pushing hydraulic cylinder installed in the leader and raising and lowering the vibro hammer along the leader. [Figure 5] It is an explanatory view showing the principle of generating the vibration excitation force. [Figure 6] It is an explanatory view showing the configuration of the pile driving support system. [Figure 7] Figures (a), (b), and (c) are graphs showing the pushing force P1 of the hydraulic cylinder used for pushing, the pushing speed v, and the excitation force P2 of the vibro-hammer for each depth of the steel pile. [Figure 8] Figure (a) is a graph showing the correlation between the value obtained by the determination formula (1) and the N value for each pile depth, and Figure (b) is a graph showing the correlation between the value obtained by the determination formula (2) and the N value for each pile depth. [Modes for carrying out the invention]

[0022] Figures 1 to 8 illustrate one embodiment of a pile driving machine that implements the pile bearing layer determination method of the present invention, and is equipped with a pile construction support system that determines the bearing layer of the pile simultaneously with the construction of the pile.

[0023] In the diagram, the pile driver 1 equipped with a pile construction support system includes a press-in type vibro-hammer pile driver 2 for driving steel piles, sheet piles, etc. (hereinafter referred to as "steel pile a") into the ground for installation, and a pile construction support system 3 for determining whether or not the steel pile a has reached the bearing layer assumed during the design phase.

[0024] The press-in combined vibro-hammer pile driver 2 comprises a base machine 4, a leader 5 positioned vertically at the end of the base machine 4 in the direction of travel, a support arm 6 attached to the end of the base machine 4 in the direction of travel and supporting the leader 5, and a vibro-hammer 7 mounted on the leader 5 so as to be able to move up and down and to apply vibration to the steel pile a.

[0025] The support arm 6 includes links 6a, 6b, and 6c arranged sequentially in the direction of travel of the base machine 4 between the base machine 4 and the leader 5, and a plurality of leader operating hydraulic cylinders 8 arranged on both the upper and lower sides of links 6a, 6b, and 6c, which operate the leader 5 via the support arm 6.

[0026] Links 6a, 6b, and 6c are each rotatably connected to each other in the vertical direction, and the base machine 4 side end of link 6a is rotatably connected in the vertical direction to the direction of travel side end of the base machine 4. Furthermore, link 6c is installed along the side of the leader 5.

[0027] The leader 5 is supported on the side of the link 6c via upper and lower brackets 9, 9, and is supported to move up and down along the link 6c by a hydraulic cylinder 10 for lifting the leader, with the link 6c positioned vertically.

[0028] The leader lifting hydraulic cylinder 10 is installed between the link 6c and the leader 5, along the link 6c and the leader 5. The lower end of the leader lifting hydraulic cylinder 10 is connected to the lower end of the link 6c, and the upper end is connected to the upper side of the leader 5.

[0029] Furthermore, by remotely operating multiple hydraulic cylinders 8 for leader operation in the control room 11 of the base machine 4, the leader 5 can stand vertically at the end of the base machine 4 on the direction of travel side, tilt forward and backward, and change its height freely. In addition, by remotely operating the hydraulic cylinder 10 for lifting and lowering the leader in the control room 11, it can move up and down along the link 6c.

[0030] Furthermore, the leader 5 incorporates a vibro-hammer lifting device 13 equipped with a hydraulic cylinder 12 for pushing the vibro-hammer 7 up and down (see Figures 4(a) and 4(b)).

[0031] The vibro-hammer lifting device 13 includes an upper pulley 14 and a lower pulley 15 positioned above and below the hydraulic cylinder 12 for pushing, respectively, and an intermediate pulley 16 positioned between the upper pulley 14 and the lower pulley 15 and connected to the rod of the hydraulic cylinder 12 for pushing.

[0032] Furthermore, it is equipped with an ascending rope 17a and a descending rope 17b, which are wound around the upper pulley 14 and the lower pulley 15 respectively, and also around the intermediate pulley 16, and an attachment block 18 attached to the vibro hammer 7 is provided between the ascending rope 17a and the descending rope 17b.

[0033] Then, by operating the hydraulic cylinder 12 for pushing in from the control room 11, the upward rope 17a and the downward rope 17b are wound onto one side, causing the vibro-hammer 7 to grip the steel pile a and move up and down along the leader 5.

[0034] In this configuration, the vibro-hammer 7 descends along the leader 5, and at the same time, vibrations are applied to the steel pile a by the vibro-hammer 7. As a result, the steel pile a, which is erected along the leader 5, is forcibly pushed into the ground by the pushing force P1 of the pushing hydraulic cylinder 12 and the excitation force P2 of the vibro-hammer 7.

[0035] The vibro-hammer 7 includes a chuck 19 that grips the upper end of the steel pile a, a vibrator 20 that applies vibration to the steel pile a via the chuck 19, and a hydraulic motor (power source) 21 that operates the vibrator 20 (Figures 3(a), (b)).

[0036] The vibrator 20 is equipped with at least one pair of eccentric weights 22, 22, which are arranged adjacent to each other horizontally and rotate in opposite directions by remote control from the control room 11. This generates a vibrating force P2 in the vertical direction (axis direction of the steel pile a) according to the rotation period of the eccentric weights 22, 22 (see Figure 5).

[0037] Furthermore, the eccentric weights 22, 22 can be remotely controlled from the control room 11 to arbitrarily set the eccentricity of the eccentric weights 22, 22, and the eccentricity of the eccentric weights 22, 22 changes as the eccentric weights 22, 22 move in the diametrical direction of the rotation axis 23, 23, respectively.

[0038] Furthermore, the excitation force P2 changes in proportion to the change in the eccentricity of the eccentric weights 22,22, and the excitation force P2 increases as the eccentricity of the eccentric weights 22,22 increases.

[0039] Furthermore, the rotational speed of the eccentric weights 22,22 corresponds to the number of strikes made against the pile head of the steel pile a, and the number of strikes of the eccentric weights 22,22 can be adjusted by remotely controlling the operating hydraulic pressure of the hydraulic motor 21 provided in the vibrator 20.

[0040] For example, when the friction on the surface of the steel pile a is high, the eccentricity of the eccentric weights 22, 22 is set to be large to increase the excitation force P2, and the operating hydraulic pressure of the hydraulic motor 21 is increased to increase the number of strikes, thereby ensuring that the steel pile a is reliably driven into the ground even in soil layers with high surface friction.

[0041] In this configuration, the vibration force P2 of the vibro-hammer 7 temporarily releases the friction on the surface of the steel pile a, and the combined weight of the vibro-hammer 7 and the steel pile a exceeds the tip resistance of the steel pile a, thereby pushing the steel pile a into the ground. Furthermore, the pushing force P1 of the hydraulic cylinder 12 is added to this, ensuring that the steel pile a is reliably pushed down to the support layer assumed by the N value.

[0042] The pile construction support system 3 is equipped with a data input unit 24 for acquiring data in real time that shows the eccentricity of the eccentric weights 22, 22 of the vibro hammer 7 when driving the steel pile a into the ground, data that shows the operating hydraulic pressure of the pushing hydraulic cylinder 12, and data that shows the penetration depth of the steel pile a and the time it took to reach that penetration depth.

[0043] Furthermore, the system includes a calculation unit 25 that calculates in real time the pushing force (cloud force) P1 and pushing speed (cloud velocity) v of the pushing hydraulic cylinder 12 and the excitation force P2 of the vibro hammer 7 at each penetration depth of the steel pile a, based on the operating hydraulic pressure of the pushing hydraulic cylinder 12, the eccentricity of the eccentric weights 22, 22, and the penetration depth and time to reach the penetration depth of the steel pile a.

[0044] Furthermore, the system includes a display unit 26 that examines and displays in real time the correlation between a value calculated using determination formula (1) or (2) from the pushing force P1 and pushing speed v of the pushing hydraulic cylinder 12 calculated in the calculation unit 25 and the excitation force P2 of the vibro-hammer 7, or from the pushing force P1 and the excitation force P2 of the vibro-hammer, and a previously investigated N value (see Figure 6). The N-value has been investigated in advance by conducting a standard penetration test within the construction area where steel pile a is to be installed.

[0045] In this configuration, the hydraulic fluid pressure of the pushing hydraulic cylinder 12 and the eccentricity of the eccentric weights 22, 22, as well as the penetration depth of the steel pile a and the time it takes to reach that depth, are input to the data input unit 24 and processed by the calculation unit 25. From these, the pushing force P1 and pushing speed v of the pushing hydraulic cylinder 12 applied to the steel pile a, and the excitation force P2 of the vibro hammer 7 are calculated in real time.

[0046] Furthermore, the correlation between the values ​​calculated using the determination formula (1) or (2) from the pushing force P1 and pushing speed v of the hydraulic cylinder 12 and the excitation force P2 of the vibro-hammer 7, and the previously investigated N-value, is examined in real time and displayed on the display unit 27 in a graph along with the support layer (see Figures 8(a) and (b)).

[0047] Furthermore, by comparing the value calculated using the determination formula (1) or (2) with the previously investigated N-value, the supporting layer at the penetration depth where a high correlation is determined is estimated to be the supporting layer for steel pile a. P1 × P2 ÷ v ……(1) P1 ÷ P2 ... (2)

[0048] Furthermore, the correlation between the value calculated by the determination formula (1) or (2) and the N value is taken into the storage unit 27 as data, organized and stored, and can be retrieved as needed to create documents such as construction reports. Furthermore, construction personnel can freely check construction information using a dedicated remote monitoring terminal, even while being located away from the construction site of steel pile a. [Industrial applicability]

[0049] The present invention enables reliable installation of support piles, such as steel piles, into a support layer assumed by the N-value, and allows for highly accurate determination of whether or not the tip of the support pile has reached the support layer. [Explanation of symbols]

[0050] 1. Pile driver equipped with a pile construction support system. 2. Vibro-hammer pile driver, 3. Pile construction support system, 4 base machine, 5 leader, 6 support arm 6a, 6b, 6c Link, 7 Vibro-hammer 8. Hydraulic cylinder for leader operation, 9. Guide 10 Hydraulic cylinder for lifting and lowering the leader, 11 Control room 12. Hydraulic cylinder for pushing, 13 Vibro-hammer lifting device, 14 Upper pulley 15 Lower pulley, 16 Intermediate pulley, 17a Ascending rope 17b Descending rope, 18 Mounting block, 19 Chuck, 20 Vibrator, 21 Motor, 22 Eccentric weight, 23 Rotating shaft, 24 Data input section, 25 calculation section, 26 display section, 27 storage section

Claims

【Request Item 1】 In a pile construction method for installing a pile into a support layer assumed by the N-value, the pile is driven by a push-and-drive vibro-hammer pile driver equipped with a leader erected at the pile installation location, a vibro-hammer mounted on the leader so as to be movable up and down and for applying vibration to the pile, and a pushing hydraulic cylinder for pushing the pile into the ground via the leader, wherein the pushing force P of the pushing hydraulic cylinder for pushing the pile into the ground 1 and the pushing speed v, and the excitation force P of the vibro-hammer that imparts vibration to the pile. 2 A method for determining whether a pile has reached a supporting layer, characterized by estimating whether the pile has reached the supporting layer assumed by the N value, based on the correlation between the value calculated by the determination formula (1) and the N value. P 1 ×P 2 ÷v……(1) 【Request Item 2】 In a vibro-hammer pile driver used in the method for determining whether a pile has reached the supporting layer according to claim 1, the pushing force P 1 , the pressing speed v and the excitation force P 2 A vibro-hammer pile driver equipped with a pile construction support system, characterized by having a memory unit that organizes and stores each value as data. 【Request Item 3】 In a vibro-hammer pile driver equipped with the pile construction support system according to claim 2, the pushing force P of the pushing hydraulic cylinder is determined from the operating hydraulic pressure of the pushing hydraulic cylinder, the eccentricity of the eccentric weight provided in the vibro-hammer, and the penetration depth of the pile and the time it takes to reach the penetration depth. 1 and the pushing speed v and the excitation force P of the vibro-hammer. 2 A vibro-hammer pile driver equipped with a pile construction support system characterized by having a calculation unit that calculates [a certain value]. 【Request Item 4】 A method for constructing a pile, in which the pile is installed in a bearing layer assumed by the N value by a combined vibro hammer pile driver including a leader erected at the installation position of the pile, a vibro hammer installed on the leader so as to be movable up and down and applying vibration to the pile, and a pushing hydraulic cylinder for pushing the pile into the ground through the leader. In the method, the pushing force P of the pushing hydraulic cylinder for pushing the pile into the ground 1 and the exciting force P of the vibro hammer for applying vibration to the pile 2 Based on the correlation between the value calculated by the determination formula (2) and the N value, it is estimated that the pile has reached the bearing layer assumed by the N value. A method for determining the reach of a pile to a bearing layer, characterized by this. P 1 ÷P 2 ……(2) 【Request Item 5】 In a vibro-hammer pile driver used in the method for determining whether a pile has reached the supporting layer according to claim 4, the pressing force P 1 and the excitation force P 2 A vibro-hammer pile driver equipped with a pile construction support system, characterized by having a memory unit that organizes and stores each value as data. 【Request Item 6】 In a vibro-hammer pile driver equipped with the pile construction support system according to claim 5, the pushing force P of the pushing hydraulic cylinder is determined from the operating hydraulic pressure of the pushing hydraulic cylinder, the eccentricity of the eccentric weight provided in the vibro-hammer, and the penetration depth of the pile and the time it takes to reach the penetration depth. 1 And the excitation force P of the vibro-hammer 2 A vibro-hammer pile driver equipped with a pile construction support system characterized by having a calculation unit that calculates [a certain value].

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