Telescopic Foundation Screw Pile with Continuously Tapered Pile Body
The embodiments provided herein are directed to a telescopic foundation screw piles with continuously tapered pile body that facilitates a faster pile placement speed, less labor and operators, less material, single step operation, low overhead clearance, no excess soils to be removed and hauled away which translates in lower cost and greater ease of use as well as higher load capacity.
The embodiments described herein generally relate to a foundation pile, in particular, to a telescopic foundation screw pile with continuously tapered pile body.
BACKGROUND OF THE INVENTIONFoundation piles are widely used (e.g., in the building or other structural fields) for anchoring a component to the ground. Typically, a foundation pile has a retaining portion in the upper region for receiving the anchored component.
A conventional drilled pile can be installed by first drilling a borehole into the ground. Then, a temporary casing is used to seal the borehole through water-bearing or unstable strata overlying suitable stable material. Upon reaching a desired depth, a reinforcing cage is introduced. Then, concrete is poured into the borehole and brought up to the required level. One disadvantage of the conventional drilled pile is that it is labor and material intensive.
An auger-cast pile, often known as a CFA pile, can be formed by drilling into the ground with a hollow stemmed continuous flight auger to a desired depth or degree of resistance. A cement grout mix is then pumped down the stem of the auger. While the cement grout is pumped, the auger is slowly withdrawn, conveying the soil upward along the flights. A shaft of fluid cement grout is formed to ground level. The Auger-cast pile causes minimal disturbance, and is often used for noise and environmentally sensitive sites. However, both the conventional drilled pile and the auger-cast pile are labor intensive, material intensive, unfit for tight spaces, unable to be placed where surcharge loads are present, high overhead clearance and depending on the situation the drilled holes could cave in and create safety concerns. For example, soils removed from the borehole need to be hauled away. In addition, where the ground in a job site is deemed to be contaminated, any soil removed from the ground must be disposed properly, which presenting an additional problem and associated cost.
A more complex system (e.g., STELCOR pile made by the IDEAL Group, 999 Picture Parkway, Webster, N.Y. 14580) whereby a pile is attached to a drill head which is substantially larger than the diameter of the pile itself. The pile is turned together with the drill head by a drilling rig to create a passage in the soil bed through which the pile may pass. A conduit is provided through the center of the pile for water or grout to be pumped down and out the tip of the drill head to either float away debris or anchor the pile in its final resting place in the soil bed. Therefore, no soil is removed during pile installation. Although the system has certain advantages over other known systems, the drilling system is obviously substantially more complex, and therefore more costly than the conventional drilled pile and the auger-cast pile discussed earlier.
Therefore, an improved foundation pile that facilitates a faster pile placement speed, lower cost and greater ease of use as well as higher load capacity is desirable.
BRIEF SUMMARY OF THE EMBODIMENTSThe embodiments provided herein are directed to a telescopic foundation screw piles with continuously tapered pile body that facilitates a faster pile placement speed, less labor and operators, less material, single step operation, low overhead clearance, no excess soils to be removed and hauled away which translates in lower cost and greater ease of use as well as higher load capacity.
Other systems, methods, features and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims. It is also intended that the invention is not limited to the details of the example embodiments.
The details of the invention, both as to its structure and operation, may be gleaned in part by study of the accompanying figures, in which like reference numerals refer to like parts. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, all illustrations are intended to convey concepts, where relative sizes, shapes and other detailed attributes may be illustrated schematically rather than literally or precisely.
In the present embodiment, the lower end 22 has a round opening 34. In one embodiment, the opening 34 has a radius of less than one inch. Alternatively, the lower end 22 can have a cone-shaped head (not shown). In one embodiment, the head is made of metal. In a further embodiment, the metal is titanium.
In the present embodiment, an annular flange 36 is attached to the upper end 24 of the body 20. In the present embodiment, the flange 36 has a plurality of holes 46 (see
In the present embodiment, the body 20 of the first section 12 is surrounded by a helical screw thread 48, which extends from the upper end 24 to the lower end 22 over the entire first section 12. In another embodiment, the helical screw thread 48 does not cover the entire first section 12.
In the present embodiment, the helical screw thread 48 is joined to the body 20 via welds. Alternatively, the helical screw thread 48 and the body 20 can be formed together or attached by mechanical means.
In the present embodiment, the body 20, the flange 36, and the helical screw thread 48 are made of metal. In one embodiment, the metal is solid steel.
The body 50 is preferably hollow internally. In the present embodiment, the body 50 is continuously tapered from the upper end 54 to the lower end 52. In one embodiment, the degree of taping (i.e., the angle 60 formed between the longitudinal axis 28 and an outer contour 62 running approximately along the longitudinal direction of the body 50) is the same through the whole body 50. Alternatively, the degree of taping can vary through the whole body 50. In a preferable embodiment, at any point of the body 50, the outer diameter at that point is greater than or equal to that at any point lower (i.e., closer to the lower end 52) and less than or equal to that at any point higher (i.e., closer to the upper end 54).
In the present embodiment, an annular lower flange 66 is attached to the lower end 52 of the body 50. In the present embodiment, the lower flange 66 has a plurality of holes 78 (see
In the present embodiment, an annular upper flange 80 is attached to the upper end 54 of the body 50. In the present embodiment, the upper flange 80 has a plurality of holes (not shown) for receiving bolts. In the present embodiment, the upper flange 80 has additional slots (not shown) for facilitating the connection of the pile 12 to a pile driving equipment (not shown) if the second section 14 is the last section of the pile 10.
In the present embodiment, the body 50 of the second section 14 is surrounded by a helical screw thread 94, which extends from the upper end 54 to the lower end 52 over the entire second section 14. In another embodiment, the helical screw thread 94 does not extends over the entire second section 14.
In the present embodiment, the helical screw thread 94 is joined to the body 50 via welds. Alternatively, the helical screw thread 94 and the body 50 can be formed together or attached by mechanical means.
In the present embodiment, the body 50, the flanges 66, 80 and the helical screw thread 94 are made of metal. In one embodiment, the metal is solid steel.
In the present embodiment, the first section 12 and the second section 14 are merged by aligning the flange 36 of the first section 12 with the lower flange 66 of the second section 14. Then, a fixing mechanism is used to merge the first section 12 with the second section 14. In one embodiment, bolting is used to merge the first section 12 with the second section 14. After the merge of the first section 12 and the second section 14, the outer contour of the merged unit are preferably smoothly aligned so that a continuously taper outer contour is still formed from the upper end 54 of the second section 14 all the way to the lower end 22 of the first section 12.
The third section 16 and the fourth section 18 can have similar structure as that of the second section 12 except that they have different lateral dimension so as to keep a continuously taper outer contour of the telescopic foundation screw pile 10 when they are merged with the first section 12 and the second section 14.
Referring back to
Although the embodiments described earlier employ holes on the flanges 36, 66, 80, 72, 76, 98 for bolt connection, other configurations can also be used for connecting adjacent sections. For example, instead of the bolted connection, a plate connection (see
The body 120 extends substantially rotationally symmetrically about a longitudinal axis 128 (see
In the present embodiment, the degree of taping (i.e., the angle formed between the longitudinal axis 128 and an outer contour running approximately along the longitudinal direction of the body 120) are different among portions 121, 123 and 125. In one embodiment, the degree of taping of the lower portion 121 is greater than that of the middle portion 123. In addition, the degree of taping of the middle portion 123 is greater than that of the upper portion 125. In a preferable embodiment, at any point of the body 120, the outer diameter at that point is greater than or equal to that at any point lower (i.e., closer to the lower end 122) and less than or equal to that at any point higher (i.e., closer to the upper end 124). Alternatively the degree of taping can be the same through the whole body 120.
In the present embodiment, the lower end 122 has a round opening 134. In one embodiment, the opening 134 has a radius of less than one inch. Alternatively, the lower end 122 can have a cone-shaped head (not shown). In one embodiment, the head is made of metal. In a further embodiment, the metal is stainless steel. Alternatively, the metal is aluminum or titanium.
In one embodiment, the length in the longitudinal direction of the lower portion 121 is 12 inches; the length in the longitudinal direction of the middle portion 123 is 52 inches; and the length in the longitudinal direction of the upper portion 125 is 8 inches.
In one embodiment, the outer diameter at the lower end 122 is 1.2 inches; the outer diameter at the joint place 127 is 3 inches; the outer diameter at the joint place 129 is 5 inches; and the outer diameter at the upper end 124 is 5 inches.
In one embodiment, the degree of taping of the lower portion 121 is 4.3°. In one embodiment, the degree of taping of the middle portion 123 is 1.1°.
In the present embodiment, the flange 136 has a plurality of holes 146 for receiving bolts. In one embodiment, the number of the holes is six. In one embodiment, the flange 136 is joined to the body 120 via welds. Alternatively, the flange 136 and the body 120 can be formed together or attached by mechanical means.
In the present embodiment, the body 120 of the first section 112 is surrounded by a helical screw thread 148, which extends from joint place 129 to joint place 127 over the entire middle portion 123. Alternatively, the helical screw thread 148 can extends from the upper end to the lower end 122 over the entire body 120.
In the present embodiment, the helical screw thread 148 is joined to the body 120 via welds. Alternatively, the helical screw thread 148 and the body 120 can be formed together or attached by mechanical means.
In the present embodiment, the body 120, the flange 136, and the helical screw thread 148 are made of metal. In one embodiment, the metal is solid steel.
In the present embodiment, the body 150 extends substantially rotationally symmetrically about a longitudinal axis (not shown), which at the same time defines the longitudinal direction of the body 150. The body 150 is preferably hollow internally.
In the present embodiment, the lower portion 151 is continuously tapered from the joint place 157 to the lower end 152; the middle portion 153 is continuously tapered from joint place 159 to joint place 157; and the upper portion 155 is continuously tapered from the upper end 154 to joint place 159. In one embodiment, the body 150 of the second section 114 is continuously tapered from the upper end 154 to the lower end 152.
In the present embodiment, the degree of taping (i.e., the angle formed between the longitudinal axis 128 and an outer contour running approximately along the longitudinal direction of the body 120) are different among portions 151, 153 and 155. In one embodiment, the degree of taping of the lower portion 151 is greater than that of the middle portion 153. In addition, the degree of taping of the middle portion 153 is greater than that of the upper portion 155. In a preferable embodiment, at any point of the body 150, the outer diameter at that point is greater than or equal to that at any point lower (i.e., closer to the lower end 152) and less than or equal to that at any point higher (i.e., closer to the upper end 154). Alternatively the degree of taping can be the same through the whole body 150.
In one embodiment, the length in the longitudinal direction of the lower portion 151 is 8 inches; the length in the longitudinal direction of the middle portion 153 is 52 inches; and the length in the longitudinal direction of the upper portion 155 is 8 inches.
In one embodiment, the outer diameter at the lower end 152 is 5 inches; the outer diameter at the joint place 157 is 5.3 inches; the outer diameter at the joint place 159 is 7 inches; and the outer diameter at the upper end 154 is 7 inches.
In the present embodiment, the lower flange 166 has a plurality of holes 178 for receiving bolts. In one embodiment, the number of the holes 178 is six. In the present embodiment, the lower flange 166 is joined to the body 150 via welds. Alternatively, the lower flange 166 and the body 150 can be formed together or attached by mechanical means.
In the present embodiment, the body 150 of the second section 114 is surrounded by a helical screw thread 194, which extends from joint place 159 to joint place 157 over the entire middle portion 153. Alternatively, the helical screw thread 194 can extends from the upper end 154 to the lower end 152 over the entire body 150 of the second section 114.
In one embodiment, the helical screw thread 194 is joined to the body 150 via welds. Alternatively, the helical screw thread 194 and the body 150 can be formed together or attached by mechanical means.
In one embodiment, the body 150, the flanges 166, 180 and the helical screw thread 194 are made of metal. In a further embodiment, the metal is stainless steel. Alternatively, the metal is aluminum or titanium.
In the present embodiment, the first section 112 and the second section 114 are merged by aligning the flange 136 of the first section 112 with the lower flange 166 of the second section 114. Then, a fixing mechanism is used to merge the first section 112 with the second section 114. In one embodiment, bolting is used to merge the first section 112 with the second section 114. After the merge of the first section 112 and the second section 114, the outer contour of the merged unit are preferably smoothly aligned so that a continuously taper outer contour is still formed from the upper end 154 of the second section 114 all the way to the lower end 122 of the first section 112.
The third section 116 and the fourth section 118 can have similar structure as the second section 114 except that they have different lateral dimension so as to keep a continuously taper outer contour of the telescopic foundation screw pile 110 when they are merged with the first section 112 and the second section 114
Referring also to
Although the embodiments described earlier employ holes on the flanges 136, 166, 180, 172, 176, 198 for bolt connection, other configurations can also be used for connecting adjacent sections. For example, instead of the bolted connection, a plate connection (see
The manufacturing process for making the telescopic foundation screw piles 10 and 110 will be described in further details hereafter. Tubes of different diameter can be selected as fabricated tubes. For example, tubes of HSS “Hollow Structural Steel” ASTM A-500 Grade A or B can be used. For example, a 5 inch diameter round tube can be selected for the first section; a 7 inch diameter round tube can be selected for the second section, etc. Then the tubes can be cut into desired section length. Then, a swaging process can be performed on the sectioned tube to reduce its diameter to form a continuously taper tube. For example, the 7 inch diameter round tube for the second section can be swaged to have a diameter of 7 inch diameter at the upper end and a 5 inch diameter at the lower end with a continuously taping. The swaging process can be either hot swaging or cold swaging.
The connection between sections can be performed by a flange to flange bolted connection as described previously in connection with the telescopic foundation screw piles 10 and 110. Individual flanges can first be fabricated to their corresponding geometry in a factory. Flanges can then be welded to the sections at the factory. The first section has one flange at its upper end. The other sections have two flanges, one at the lower end and one at the upper end. Then, the sections are installed in the field by bolting the corresponding flanges from connecting sections. The upper flange of the last (the up most) section can have slots for connecting the pile to a pile driving equipment.
Alternatively, the connection between sections can be performed by a plate connection.
Alternatively, the connection between sections can be performed by a threaded rod connection.
Although the flange to flange bolted connection, the plate connection, and the threaded rod connection described hereinbefore are used mutually exclusive in different embodiments, a pile can be fabricated and installed with more than one connection schemes if desired.
The telescopic foundation screw piles 10, 110, 210, 310 described herein have several advantages. First, there is no requirement of pre-drill or digging to the soils for installation of the telescopic piles. Therefore, there is no potential spoils or cross contamination. In addition, there is no requirement of refilling of concrete or grout, resulting in a fast, simple, low cost and ease of use installation processing.
In addition, the use of telescopic piles with variable number of sections, which can be flexibly chosen, based on the desired depth of the foundation, can reduce the cost of materials. In addition, energy for drilling can be reduced.
In addition, the continuously taping outer contour of the telescopic piles provides a uniformly lateral pressure to the soils in terms of the depth of the foundation, resulting in an improved soil density around the installed telescopic piles so as to achieve a higher load capacity.
In addition, the continuously taping outer contour of the telescopic piles provides an increased skin friction. Nordlund developed a method of calculating skin friction based on field observations and results of several pile load tests in cohesionless soils. Several pile types were used, including timber, H type steel, pipe, monotube, etc. The method accounts for pile taper and for differences in pile materials. Nordlund indicates that the unit skin friction is increased by a factor of at least 1.5 for an angle of taper of 0.5 degrees (approximately 1%). (See page 119, M. J. Tomlinson, Pile Design and Construction Practice, fourth edition, Tayler and Francis, Oxon, UK, 1994.)
While the invention has been described in connection with specific examples and various embodiments, it should be readily understood by those skilled in the art that many modifications and adaptations of the invention described herein are possible without departure from the spirit and scope of the invention as claimed hereinafter. Thus, it is to be clearly understood that this application is made only by way of example and not as a limitation on the scope of the invention claimed below. The description is intended to cover any variations, uses or adaptation of the invention following, in general, the principles of the invention, and including such departures from the present disclosure as come within the known and customary practice within the art to which the invention pertains.
Claims
1. A telescopic foundation screw pile comprising:
- a first section having a lower end, an upper end, and a continuously tapering body surrounding by a helical screw thread; and
- a second section having a lower end, an upper end, and a continuously tapering body surrounding by a helical screw thread, wherein the first section and the second section form a continuously tapering outer contour from the upper end of the second section all the way to the lower end of the first section.
2. The telescopic foundation screw pile of claim 1, wherein the helical screw thread of the first section covers a portion of the body.
3. The telescopic foundation screw pile of claim 1, wherein the helical screw thread of the second section covers a portion of the body.
4. The telescopic foundation screw pile of claim 1, wherein the first section has a flange attached to the upper end.
5. The telescopic foundation screw pile of claim 1, wherein the second section has a lower flange attached to the lower end and an upper flange attached to the upper end.
6. The telescopic foundation screw pile of claim 5, wherein the flange of the first section is merged with the lower flange of the second section.
7. The telescopic foundation screw pile of claim 6, wherein the flange of the first section and the lower flange of the second section is merged by bolting.
8. The telescopic foundation screw pile of claim 6, further comprising a third section having a lower end, an upper end, and a continuously tapering body surrounding by a helical screw thread, wherein the third section has a lower flange attached to the lower end and an upper flange attached to the upper end, and wherein the upper flange of the second section is merged with the lower flange of the third section.
9. The telescopic foundation screw pile of claim 8, further comprising a fourth section having a lower end, an upper end, and a continuously tapering body surrounding by a helical screw thread, wherein the fourth section has a lower flange attached to the lower end and an upper flange attached to the upper end, and wherein the upper flange of the third section is merged with the lower flange of the fourth section.
10. A telescopic foundation screw pile comprising a plurality of sections connected together to form a single unit, wherein the unit has a continuously tapering body surrounding by a plurality of helical screw threads.
11. The telescopic foundation screw pile of claim 10, wherein the number of the plurality of sections is four.
Type: Application
Filed: Mar 14, 2014
Publication Date: Oct 9, 2014
Inventor: Edick Shahnazarian (Los Angeles, CA)
Application Number: 14/211,673
International Classification: E02D 5/56 (20060101);