Hammering system with electromagnetic power for dynamic pile testing

Abstract

A new hammering system with electromagnetic power for dynamic pile testing. The basic working principle of the hammering system is as follows: when an internal coil is energized, a magnetic force is generated to attract tightly, via a magnetic conduction panel, an adaptive weight hammer disposed in contact with the surface of the panel; when the internal coil is de-energized, demagnetization occurs, and the weight hammer falls instantaneously to impact the pile top, thereby achieving the effects of a stable weight hammer and quick attraction and falling of the hammer. A clamping scale is arranged inside an adjustment section of a guide frame. A falling height of the weight hammer may be selected arbitrarily.

Claims

1. A hammering system with electromagnetic power for dynamic pile testing, comprising: an electromagnetic detacher, wherein when an internal coil of the electromagnetic detacher is energized, a magnetic force is generated to attract tightly, via a magnetic conduction panel, an adaptive weight hammer disposed in contact with the surface of the panel; when the internal coil is de-energized, demagnetization occurs, and the weight hammer falls instantaneously to impact a pile top as the magnetic force disappears; when the internal coil is energized again, a magnetic force is generated to attract the weight hammer again for performing next hammering; the electromagnetic detacher is a box-like component, which comprises a bottom shell, an iron core, a coil, a panel, a cable connection box, a current rectification control cabinet, a cable drum connectable to a power supply, and a wireless remote controller, and is powered by a direct current; the hammering system comprises a cylindrical box in which a coil of a corresponding number of turns is wound according to an attraction force requirement; and wherein, in dynamic pile testing, the electromagnetic detacher is placed on the top surface of the weight hammer by using a crane, and energized to attract the weight hammer and lift it to a desired height; then, the electromagnetic detacher is de-energized, and demagnetization occurs to release the weight hammer; since the de-energization and the hammer falling are completed instantaneously, the weight hammer falls freely to the pile top without any external force.

2. The hammering system with electromagnetic power for dynamic pile testing according to claim 1, wherein a retractable guide frame is of a steel structure comprising a base section and an adjustment section; the base section has trapezoidal side surfaces and square top and bottom surfaces; a side length of the bottom surface of the base section is 4 m; the adjustment section has rectangular side surfaces and square top and bottom surfaces; and the adjustment section is sleeved with the base section.

3. The hammering system with electromagnetic power for dynamic pile testing according to claim 1, wherein a hammer cushion is of a sheet structure comprising a steel plate, rubber, and an air bag, and has a specification the same as that of the bottom surface of the weight hammer.

4. The hammering system with electromagnetic power for dynamic pile testing according to claim 1, wherein the hammering system generates a magnetic force or undergoes demagnetization through energization or de-energization, thereby achieving the effects of a stable weight hammer and attraction and falling of the hammer.

5. The hammering system with electromagnetic power for dynamic pile testing according to claim 1, wherein a retractable guide frame is of a steel structure comprising a base section and an adjustment section; support legs and support leg leveling devices are arranged at four corners of the bottom of the guide frame; the support leg leveling devices being individually adjustable such that the support legs are located on the same level such that the guide frame is vertical and stable.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a longitudinal sectional view of a hammering system with electromagnetic power for dynamic pile testing.

(2) FIG. 2 is a structural view of an adaptive weight hammer.

(3) FIG. 3 is a longitudinal sectional view of a base section of a retractable and levelable guide frame.

(4) FIG. 4 is a longitudinal sectional view of an adjustment section of the retractable and levelable guide frame.

(5) FIG. 5 is an external view of a clamping scale.

(6) FIG. 6 is an overall external view of the hammering system according to the present invention.

(7) FIG. 7 is an external view of a special hammer cushion of the present invention.

DETAILED DESCRIPTION

(8) The present invention will be further described below in combination with the drawings.

Embodiment

(9) As shown in drawings, the operating steps of an electromagnetic hammering system are as follows. When an internal coil is energized, a magnetic force is generated to attract tightly, via a magnetic conduction panel, an adaptive weight hammer disposed in contact with the surface of the panel. When the internal coil is de-energized, demagnetization occurs, and the weight hammer falls instantaneously as the magnetic force disappears.

(10) When the internal coil is energized again, a magnetic force is generated to attract the weight hammer again for performing next hammering. The electromagnetic detacher 10 is a box-like component, which consists of a bottom shell 12, an iron core 14, a coil 16, a panel 18, a cable connection box 20, a current rectification control cabinet 22, a cable drum 24 and a wireless remote controller 26 and is powered by a direct current, thereby achieving stable and powerful attraction and low remanence. In consideration of the weight and shape of the hammer as well as uniform and stable attraction, the electromagnetic detacher is designed as a cylindrical box in which a coil of a corresponding number of turns is wound according to an attraction force requirement. The electromagnetic detacher is placed on the top surface of the weight hammer 30 by using a crane, and energized to attract the weight hammer and lift it to a desired height. Then, the electromagnetic detacher is de-energized, and demagnetization occurs to release the weight hammer. Since the de-energization and the hammer falling are completed instantaneously, the weight hammer falls freely to the pile top without any external force, and is stable and centered.

(11) A retractable guide frame in the present invention is of a special steel structure consisting of a base section and an adjustment section. The base section has trapezoidal side surfaces and square top and bottom surfaces. A side length of the bottom surface of the base section is 4 m. In addition, the steel is widened and thickened to meet the supporting force requirements. The base section consists of three sections, and the height of each section may be determined according to parameters such as hammer weight and pile diameter. A ladder is welded to one side of the base section to facilitate climbing when needed. The adjustment section has rectangular side surfaces and square top and bottom surfaces. The adjustment section is sleeved with the base section. When an elevation of the pile top is much higher than the ground, the adjustment section may be lifted to adapt to the requirements on a falling distance. On the contrary, when the elevation of the pile top is at a depth below the ground, the adjustment section may be lowered. A clamping scale is arranged inside the adjustment section at intervals of 10 cm to facilitate control of the falling distance of the weight hammer. In addition, support leg leveling devices are arranged at four corners of the bottom surface of the base section respectively to adapt to the case where a site is uneven. When no leveling is required, the support leg devices are fixed inside the guide frame for easy transportation and protection. If leveling is required, the support legs in all directions may be pulled out conveniently and individually adjusted to ultimately ensure that the four legs of the guide frame are located on the same level, such that the guide stable is vertical and stable as a whole. By means of such a retractable and levelable design, the hammer may be guided and controlled to fall stably in a centered manner, so as to adapt to different working conditions through stretching and retracting the adjustment section and leveling the support legs, thereby achieving high adaptability.

(12) A special hammer cushion is of a sheet structure consisting of a steel plate, rubber, and an air bag and has a specification the same as that of the bottom surface of the weight hammer.

(13) The hammering system generates a magnetic force or undergoes demagnetization through energization or de-energization, thereby achieving the effects of a stable weight hammer and quick attraction and falling of the hammer.

(14) During operation, two strain sensors and two acceleration sensors are installed symmetrically at a position about two times the pile diameter under the pile top, and are connected with a main cable. The main cable is connected with an data acquisition main unit. When everything is ready, the main unit can wait for the impact from the falling hammer and collects data.

(15) A hammer head is lifted and placed on the top of the tested pile by using a crane to ensure that the center of gravity of the weight hammer is consistent with the center of the pile.

(16) The hammering system is lifted and placed on the top surface of the weight hammer by using the crane.

(17) The retractable and levelable guide frame is lifted by using the crane and nested to the outside of the hammering system and the weight hammer which are connected. The base section is kept stable and horizontal. When the site is uneven, the support legs at the bottom are pulled out and leveled. After the guide frame is well fixed, a main hook of the crane extends to a lifting lug of the hammering system and waits for energization to attract the weight hammer. A cable drum is connected to a power supply. An alternating current is converted to a direct current through a current rectification control cabinet, such that the electromagnetic detacher is energized to attract the weight hammer. The weight hammer is lifted to a specified clamping scale position, i.e., the weight hammer is lifted to a desired falling height.

(18) After de-energization and demagnetization, the weight hammer falls stably to the pile top, and force and velocity impedance time curves are acquired.

(19) After signals are collected, the hammering system is lowered to the top surface of the weight hammer by using the crane and then energized to generate a magnetic force to attract the weight hammer. The above steps are repeated to perform a next impact action and continuously collect data.

(20) At last, after the data quality meets the requirements, the test is ended.

(21) Those solutions that achieve the above technical effects by use of the technical solutions described in the present invention, or similar technical solutions designed by those skilled in the art under the inspiration of the technical solutions of the present invention all shall fall into the protection scope of the present invention.