Patent Application
20150284926
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Not Applicable.
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Not Applicable.
Piles as deep foundation are widely used to transfer loads from top structure to soil. In general, larger and longer piles may take more loads such as bearing, uplifting and lateral, while going deeper into the soil may achieve better results of loading.
However, due to space, structural and cost restrictions, increasing pile dimension, length and numbers are not always possible.
Therefore, there is a need for increasing the pile capacity to meet engineering standards, without increasing pile size and/or its length. In addition, there is a need in increasing the pile capacity with minimum overall costs that includes installation.
The current invention relates to an device having an explosive device. Said device is installed at a tip or attached along a length of a pile and the method using thereof.
One object of the present invention is to installing the device on the tip of a conventional pile. Alternatively, the present invention may be attached or inserted into middle part of the conventional pile. Thus the fabrication and installation of the pile provided with the device are basically the same as the conventional ones except the installation of the present invention.
Yet another object of the present invention is to use explosives to form at least one ellipse-like or lantern-like shapes of balloons 10, which can squeeze surrounding soil and greatly increase the bearing, uplifting, lateral and overturning bending of the pile.
In one embodiment of the present invention, the device consists of a main pipe connection 3, a bearing pipe 10 and an end cone section 20 along with an explosive device.
The present invention is related to a device having an explosive device installed at a tip or attached along a length of a pile, and a method of using thereof. As shown in
Alternatively, the device may be inserted into middle part of the pile. For example, the device consists of the bearing pipe and two of the main pipe connections. Each main pipe connection has one of its ends connected to one end of the bearing pipe along its length, respectively.
Accordingly, the bearing pipe and the main pipe connection have their diameters the same as the pile installed, attached or inserted.
The main pipe connection 3 may be connected to the bearing pipe 10, for example, by means of a steel pin 4. The end cone section 20 may be connected is to the bearing pipe 10, for example by treading onto said bearing pipe and mounted by four screws 17. The explosive device is located inside the bearing pipe 10.
In general, the main pipe connection 3, the bearing pipe 10 and the end cone section 20 can be structural steels, stainless steels, copper and/or copper alloys, aluminum and/or aluminum alloys. It is required for the pile to have relative high yield stress, ultimate strength and especially high ductility.
Accordingly, the bearing pipe further consists of:
1) A bottom laminated structure 6-7 and a top laminated structure 27-28, both of which are made of a set of layered structures or a fiber reinforced composite structure and fixed to either end of the bearing pipe, respectively.
2) The explosive device, which is made of a main explosive area 9, an explosive holder 13, a detonating cord 25, and a detonating point 5.
3) A plurality of reinforcing rings 8&15 surrounding the second diameter of the bearing pipe, which may greatly reduce pipe expansion after blasting.
The laminated structures 6-7, 27-28 can be composed of two-layered and/or multi-layered structures, but must at least be made of two different layering materials.
For the two-layered laminated structure, a first layer made from a first layering material must have low sound impedance relative to a second layer made of a second layering material. The layering materials may be included but not limited to structure steel, stainless steels, steel alloys, copper/copper alloys, aluminum/aluminum alloys.
For a multi-layered laminated structure, one of the layering materials must have low sound impedance relative to the other layering materials.
The laminated structures 6-7 and 27-28 may have the same layer number and same layer materials, but may also have different layer numbers and layer material, depending on the individual situation.
The layering material can be composed of metal and/or non-metal materials.
Alternatively, the laminated structures may be replaced with fiber reinforced composite structures 6-7, 27-28 comprising of carbon fiber and epoxy matrix composite, or glass fiber and epoxy matrix composite, or any other fiber reinforced composites.
The purpose of the explosive holder 13 is to hold the explosive. By changing the explosive holder's shape, length 22, and diameter 14, the pipe's shape formed after blasting may be controlled, so that it can bear maximum force. Usually, after blasting, the OD 11 of the bearing pipe 10 will be more then doubled. The area will increase four-fold.
An explosive wave propagates along the detonating point 5 and the detonating cord 25. A plurality of holes 26 are uniformly distributed around the explosive holder 13 as shown in
Through the holes 26, the explosive wave can smoothly and uniformly propagate to the main explosive area 9 filled with an explosive. The explosive includes but not limited to the following: TNT, RDX, HMX, and COMPOSITE B. Alternatively, the explosive may be replaced by a variety of Solid Propellants or Liquid Propellants.
When the explosive detonated, it creates extremely high pressures e.g., CJ pressure of HMX can be more than 35.8 GPa. After the explosive blasts, in general, the pin 4 which holds together the main pipe connection 3 and the bearing pipe 10 may suffer damage if not protected. So might be the end cross section 20. However, by controlling the weight and shape of the explosive, it is possible to keep the pipe's integrity, which means no break to the device and the pile. It is also possible to select different explosives that have lower CJ pressures to achieve same result described hereahove.
The capability of the dispersion of the shock wave mainly depends on the sound impedance differences between the layering materials. A shock wave disperses very quickly when a propagates in the laminated structures in which the layering materials have different sound impedance or in fiber-reinforced composite structures. In order to achieve the best dispersing results, the direction of the shock wave may be perpendicular with respect to the layers of the layered structures or to fiber lines of the fiber-reinforced composite structures.
The laminated structure 6 must be mounted to the device, for example, by welded onto the bearing pipe 10 so that the structures will be much stronger to prevent the pin 4 from damage. The laminated structures 27-28 may not necessary been welded onto the bearing pipe. For example, they may be mounted onto the explosive holder using a bolt 16.
The shock wave propagating in the laminated structures 6-7 and 27-28 will quickly attenuate. A pressure of a front shock wave will be greatly reduced after propagating through the laminated structures. However the laminated structure 6 welded to the bearing pipe 10 might partially detached therefrom under intensive high loading of the explosive. Additionally, a high-pressure explosion gas will be released through the detonating cord 25. The pressure left would be below yield strength of the device and the pile, which will therefore not be broken. In this way, the integrity of the bottom structure can still be kept, and the pin 4 may not be damaged or broken.
The enhance rings 8 and 15 may be composed of various metals and non-metals, such as structure steel stainless steels, aluminum/aluminum alloys, copper/copper alloys, titanium/titanium alloys, rubbers, plastics, fiber-reinforced composites, laminated structures, etc.. but not limited to the above list.
Under the action of the explosive, the bearing pipe 10 will quickly expand outward. A high pressure of an outside surface of the bearing pipe 10 will compress a soil outside the pipe 10 and make it even harder and stronger. In return, said pressure on the outside surface of the pipe 10 will sustain even higher than situations in which only the pipe 10 presses the soil.
When propagating from the bearing pipe 10 to the soil, the shock wave will reflect from and be incident to the soil. According to Theory of Shock Wave Physics, the reflected wave is a rare wave, while the incident wave is a compressive wave which makes the density of the soil increasing and thereafter strengthens the soil.
In a conventional situation, the pile bears a friction force F2 which is P*□ where P is a normal pressure and □ is a friction coefficient, respectively. However, according to the present invention, the pile bears not only the friction force F2, but also a normal force F1 which is much larger than the friction force as shown in
Yield stress of a material will significantly increase with high strain rate >10̂3/sec. To estimate the interaction of tire explosive and the bearing pipe 10, one has to consider above factor. A proper method of estimation is numerical simulation using AUTODYN, a finite different code or other dynamic finite element codes. Most metals with high strain rate are sensitive to temperature. So when carrying out analysis, the temperature is another factor to be considered.
It is to be understood that the use of “including”, “comprising” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items; the terms “a” and “an” herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item; and, the use of terms “first”, “second”, and the like, herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another.
It is to be understood that the above embodiments and examples are provided as illustrations only, and do not in any way restrict or define the scope of the present invention. Various other embodiments may also be within the scope of the claims.
