The present invention relates to systems and methods of stabilizing soil, and more particularly, to a soil nail launcher used to emplace soil nails.
In order to stabilize soil and rock formations, it is known to utilize soil nailing in which a plurality of elongate reinforcing members are driven into the ground in an array in order to improve the bulk properties of the surrounding soil and rock.
One reference that discloses a device and method of soil nailing includes the U.S. Pat. No. 5,044,831, the disclosure of which is hereby incorporated by reference.
Two additional examples of references that disclose soil nailing techniques includes the British Patent No. 1,580,142, and the European Patent 0 239 258.
While these references may be adequate for their intended purposes, there is still a need to provide an improved soil nailing device that is easier to maintain, as well as one that is more efficient by having the capability to launch a greater number of soil nails over a period of time.
The portion of the soil nailing device that contacts the ground when a nail is being launched is referred to as the shroud or baffle assembly which enables the distribution of pressure away from the barrel of the launcher, and also captures any fragments that are carried through the barrel, such as the sabot or collett which is attached to the distal tip of the soil nail. As time progresses, the baffle may become clogged with soil or other debris, thereby limiting its ability to effectively release high-pressure from the barrel. The baffle may become damaged over time, thereby also changing it pressure-relieving characteristics. The failure to consistently relieve pressure from the barrel as the nail is launched can negatively affect the depth of the launched nail. Therefore, there is a need to provide an improved design for the baffle to ensure it captures fragments launched from the barrel, yet allows effective pressure release from the barrel.
Another disadvantage of existing soil nailing devices is that it may take an inordinate amount of time to pressurize the device so that a nail can be launched. One type of soil nailing device includes a barrel having a coaxial arrangement of an inner tube/casing and an outer tube/casing. The annular space between the inner and outer tubes is pressurized, and supplies the motive force for launching the soil nail by release of pressure within this annular space into the breach of the barrel. This annular space is pressurized by a source of compressed gas. Preferably, the source of compressed gas includes a plurality of pressurized containers that are stored on a deployment vehicle that transports and secures the launching device. One limiting factor in how quickly soil nails can be launched depends upon the time in which it takes to adequately pressurize the annular space for the next nail to be launched. Because of the noise associated with the launching of a nail, safety requirements for construction along highways and other roads generally require that traffic be stopped during the launching of a nail. The more quickly the soil nails can be launched, the less disruption for traffic flow and of course the more quickly a job can be completed. Therefore, there is also a need to provide a soil nail launching device that has a shorter cycle time in terms of the number of soil nails that can be launched in a period of time.
Additionally, there is also a need to reduce the required pressure to launch a nail, yet still achieving the same depth of penetration for a soil nail that is launched. A reduced pressure requirement will inherently reduce the time to launch successive nails.
In accordance with the present invention, an improved soil nail launching device is provided with two primary improvements. The first improvement of the present invention relates to a construction for the shroud that enables adequate pressure distribution from the barrel after a launch, yet minimizes clogging of the shroud by provision of removable shroud plates, thereby easing maintenance efforts.
A second improvement of the present invention relates to an improved barrel construction in which the compressed gas within the annular space between the inner and outer tubes can be more efficiently evacuated into the breach, thereby reducing the actual pressure requirement in the annular space for launching a soil nail to a desired depth. This reduced pressure requirement within the barrel also results in a shorter cycle time for consecutive firing of multiple soil nails at a particular job site. Additionally, the reduced pressure requirement also increases the life of the soil nail launcher by creating less stress on the various seals of the breach and valving that will inherently fail over time and require replacement.
With respect to the first improvement of the present invention, the construction of the shroud has been modified by providing the plurality of removable shroud plates attached to a perforated cage. The removable plates are spaced from one another along the cage, yet have parallel side edges that are closely spaced from one another to prevent escape of fragments exiting the barrel. The plates are easily removed from the cage, thereby easing maintenance efforts in replacing damaged plates and to remove debris around the plates.
With respect to the second improvement of the present invention, the pathway between the annular gap between the tubes of the barrel and the cavity or chamber within the breach has been improved such that the annular gap can be more quickly evacuated during operation, thereby providing an increased volume of air which pressurizes the chamber within the breach, and therefore increases the force by which the soil nail is driven into the soil. More specifically, a connection between the breach and the barrel has been improved such that there is no constriction as the compressed air travels through that connection and then into the chamber of the breach.
Various other features and advantages of the present invention will become apparent from a review of the following detailed description, taken in conjunction with the accompanying drawings.
The primary components of the launching device 10 include a barrel 34, a breach 36 located at one end of the barrel and a shroud assembly 38 located at the opposite end of the barrel. A frame 40 comprising a number of angled plates provide a stable mounting for the launcher components. A front support 42 and a rear support 46 allow the launcher to be placed horizontally on the ground when not in use. The rear support 46 also acts as a housing for valve bank 44, as described below.
Now referring to
Referring now to
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A slight uniform gap exists between each abutting side edge of adjacent removable plates 84. With this specific arrangement of the removable plates 84, venting of the pressurized air within the cage 80 can be achieved, yet debris and fragments exiting the barrel during launching will not escape from the cage. In the event one of the removable plates is damaged or is clogged with debris, the plate can be easily removed. With the use of the removable plates 84, precise relieving pressures can be maintained which improves the operation of the launching device.
Referring to
The breach 38 includes a breach block housing 90, a breach block end plate 92, and a valve plate area 130. In
In the prior art design, the portion of the breach terminating at the barrel includes a flange 150. The end 148 of the outer tube 140 of the barrel is fitted over the flange 150, such as by a threaded connection. As shown, by the directional arrows, when the compressed air from the annular space 146 is allowed to travel into the breach cavity 134, it must first pass through an annular constriction 152 located at the flange 150. This constriction 152 is defined by the narrowed area between the inner tube 142 and flange 150. This constriction is smaller in area as compared to the annular space 146. Because of this constriction 152, gas cannot be evacuated from the annular space 146 as quickly as if there were no constriction there.
The basic operation of the launching device is as follows. First, the compressed source of gas 144 pressurizes the annular space 146 located between the inner and outer tubes 140 and 142. Once the annular space 146 is pressurized to the set point, then the launcher can be fired by operating valves (not shown) located at the valve plate area 130, which opens a corresponding plurality of passageways (not shown) between the cavity 134 and the annular space 146. As mentioned above, the valve plate area 130 is simplified by the illustration of the single annular passageway 132. As the cavity 134 quickly pressurizes, the soil nail is forced through the barrel as shown by the directional arrow within the bore 160 of the barrel. An o-ring shaped metallic anvil (not shown) is placed around the central opening in the base plate. The anvil has a diameter large enough to allow passage of the soil nail to enter the ground, yet the diameter of the anvil is such that the larger diameter collett strikes the anvil and breaks apart into fragments. Pressurized air is prevented from escaping the cavity 134 by the breach cap 122 that is maintained in its position as shown. The nail passes completely through the breach cap 122 and when enough pressure is relieved in the breach cavity, the breach cap may also be carried along with the spacer to the anvil where they are also fragmented by striking the anvil.
Now referring to
By redesigning the connection between the breach and the barrel, improved air flow is achieved which allows a more immediate evacuation of the compressed gas into the breach chamber, thereby increasing the speed at which the soil nail can be driven into the ground. This solution is preferable over a complete redesign of the complex valve plate assembly and valving, which otherwise would be a much more complex and expensive redesign effort.
By the foregoing, it is apparent that two improvements are provided to an existing soil nail launching device to improve the overall operation and performance. These improvements are achieved without requiring a complete resign of the basic function of the soil nail launching device.
Although the foregoing invention has been shown with respect to various preferred embodiments, it should be understood that various other changes and modifications may be made within the spirit and scope of the invention.
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Number | Date | Country | |
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20090277943 A1 | Nov 2009 | US |