MICROTUNNELING METHOD
A microtunneling method includes: (a) forming a working well; (b) boring a tunnel from the working well through waterjet techniques which use at least one waterjet cutter including a jet seat and a jet nozzle mounted rotatably on the jet seat, the tunnel being bored by moving progressively the jet seat along a circular path and by rotating the jet nozzle relative to the jet seat; (c) removing excavated soil, rocks or gravel from the tunnel; and (d) advancing the waterjet cutter along an axis of the circular path.
1. Field of the Invention
This invention relates to a microtunneling method, more particularly to a microtunneling method using waterjets techniques.
2. Description of the Related Art
Conventional contact-type tunnel boring machines normally have disadvantages, such as the inability of providing sufficient friction and abutment force during cutting a hard rock structure or the problem of undesired attachment of cement onto the cutting head during cutting a cement structure, which results in a decrease in cutting efficiency. As a consequence, there is normally required additional manpower to bore the tunnel and to remove the attached cement on the cutting head. In microtunneling (tunnel diameter less than 900 mm), particularly, for tunnel diameter less than 600 mm, the aforesaid drawbacks become more severely, and result in an increase in the operation cost, a decrease in boring efficiency, dust and noise pollution problems, safety concerns, insufficient emergent response space, etc.
Although the structure of the hard working surface of the cement structure can be pre-weakened before the actual cutting operation, only a limited area of the hard working surface covered by the first and second jet nozzles 161, 171 is pre-weakened, and the structure of the remainder area of the hard working surface remains relatively strong. Hence, the effect of facilitating the subsequent cutting operation through pre-weakening of the structure of the hard working surface using the first and second waterjet units 16, 17 is limited.
SUMMARY OF THE INVENTIONTherefore, the object of the present invention is to provide a microtunneling method that can overcome the aforesaid drawback associated with the prior art.
According to this invention, there is provided a microtunneling method that comprises: (a) forming a working well; (b) boring a tunnel from the working well through waterjet techniques which use at least one waterjet cutter including a jet seat and a jet nozzle mounted rotatably on the jet seat, the tunnel being bored by moving progressively the jet seat along a circular path and by rotating the jet nozzle relative to the jet seat; (c) removing excavated soil, rocks or gravel from the tunnel; and (d) advancing the waterjet cutter along an axis of the circular path.
Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiments of this invention, with reference to the accompanying drawings, in which:
Before the present invention is described in greater detail, it should be noted that same reference numerals have been used to denote like elements throughout the specification.
In this embodiment, the first waterjet cutter 3 further includes a first circular rail 31 that defines the first circular path 300. The first nozzle seats 332 are mounted slidably on the first circular rail 31, and are moved progressively and intermittently along the first circular rail 31 during the boring operation. Each of the first nozzle seats 332 is moved a predetermined pace on the circular path 300 each time. Each of the first jet nozzles 331 is then actuated and is rotated 360 degrees relative to the respective first nozzle seat 332 so as to form a circular groove 34 in a working surface 201 of the tunnel 200 each time (see
The first circular rail 31 is received in and is secured to a tubular tunnel support 2 (see
A pumping unit 6 includes a pump 63 connected to a chamber defined by the tubular tunnel support 2 through a mud pipe line 61 and a water pipe line 62 so as to remove the excavated soil, rocks or gravel collected in the chamber of the tubular tunnel support 2.
By virtue of the configuration of the first and second waterjet cutters 3, 9 used in the microtunneling method of this invention, the aforesaid drawback associated with the prior art can be eliminated.
While the present invention has been described in connection with what are considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation and equivalent arrangements.
Claims
1. A microtunneling method comprising:
- (a) forming a working well;
- (b) boring a tunnel from the working well through waterjet techniques which use at least one first waterjet cutter including a first jet seat and a first jet nozzle mounted rotatably on the first jet seat, the tunnel being bored by moving progressively the first jet seat along a first circular path and by rotating the first jet nozzle relative to the first jet seat;
- (c) removing excavated soil, rocks or gravel from the tunnel; and
- (d) advancing the first waterjet cutter along an axis of the first circular path.
2. The microtunneling method of claim 1, wherein the first waterjet cutter further includes a first circular rail that defines the first circular path, the first nozzle seat being mounted slidably on the first circular rail, and being moved progressively and intermittently along the first circular rail during the boring operation.
3. The microtunneling method of claim 2, wherein in step (b), a second waterjet cutter is further included to bore the tunnel, the second waterjet cutter including a second circular rail that is disposed coaxially with the first circular rail, a second nozzle seat that is mounted slidably on the second circular rail, and a second jet nozzle that is mounted rotatably on the second jet seat, the second nozzle seat being moved progressively and intermittently along the second circular rail and the second jet nozzle being rotated relative to the second nozzle seat during the boring operation.
4. The microtunneling method of claim 2, wherein the first circular rail is received in and is secured to a tubular tunnel support, advancement of the tubular tunnel support in the tunnel along the axis being conducted using pipe jacking techniques.
Type: Application
Filed: Sep 20, 2007
Publication Date: Mar 26, 2009
Applicant: Taiwan Water-Jets Technology Co. Ltd. (Kaohsiung City)
Inventor: Piin-Tsung Cheng (Kaohsiung City)
Application Number: 11/858,317
International Classification: E21B 7/18 (20060101);