KR20180034584A - Open floor expandable shells and related methods for supporting pier construction - Google Patents

Abstract

Expandable shells and associated methods for constructing support piers are disclosed. The expandable shell defines an interior for retaining the particulate construction material and may define a first opening at the first end and a second opening at the second end for receiving the particulate construction material therein. The expandable shell may be flexible such that the shell expands when the particulate construction material is consolidated within the shell. The method can include locating the expandable shell on the ground and filling at least a portion of the interior of the shell with the particulate construction material. The particulate construction material may be consolidated within the expandable shell to form a support pier.

Description

Open floor expandable shells and related methods for supporting pier construction

[0001] This application is an international patent application filed on July 27, 2015, which claims priority to U.S. Serial No. 14 / 809,579, the disclosure of which is incorporated herein by reference in its entirety.

[0002] The present invention relates to ground or soil improvement devices and methods. More particularly, the present invention relates to open-end extensible shells and associated methods for constructing a support pier.

[0003] Buildings, walls, industrial facilities and transport-related structures typically include shallow foundations such as spread footings or driven piles or drilled shafts And deep foundations such as. Shallow foundations are much cheaper to build than deep foundations. Thus, deep foundations are generally used only if the shallow foundations can not provide enough bearing capacity to withstand the settlement and support the building weight.

[0004] Recently, ground improvement techniques such as jet grouting, soil mixing, stone columns and aggregate columns have been used to improve the soil sufficiently to allow the use of shallow foundations . Cement-based systems such as grouting or mixing methods can sustain heavy loads, but are relatively costly. Stone pillars and aggregate pillars are generally more cost effective but may be limited by the load bearing capacity of the pillars in soft clay soils.

[0005] In addition, it is known in the art to use metal shells for driving and forming concrete piles. One set of examples includes U.S. Patent Nos. 3,316,722 and 3,327,483 to Gibbons, which discloses putting a tubular metal shell tapered to the ground to form a pile and subsequently filling the shell with concrete . Another example is U.S. Patent No. 3,027,724 to Smith, which discloses installing shells on the ground for subsequent filling into concrete to form concrete piles. A disadvantage of these prior art shells is that the sole purpose of these shells is to provide a temporary form for insertion of the cementitious material to form a cured pile for structural load support. The prior art shells are not extensional and thus do not exhibit properties that allow them to bond to surrounding soil through lateral deformations. Moreover, since the shells are associated with the use of ferrous materials that can be corroded, the function of the shells is completed when the concrete infill is cured. Thus, the prior art shells are not suitable for containing less expensive particulate filler materials, such as sand or aggregate, because prior art shells can not contain embedded materials laterally during the life of the pier. Prior art shells are also not permeable and thus are not suitable for draining clays.

[0006] It is therefore an object of the present invention to provide an improved method of forming an aggregate of a soil or an aggregate by using expanded shells formed from relatively permanent materials of substantially non- It is desirable to provide improved technology for constructing shallow support piers on the ground.

[0007] Expandable shells and related methods for constructing support piers on the ground are disclosed. The expandable shell may define an interior for retaining particulate construction material and may define an opening for receiving particulate construction material therein. The shell may be flexible such that the shell expands laterally outward when the particulate construction material is consolidated within the shell.

[0008] According to one aspect, the shell may include a first end defining an opening. The shell may be shaped to taper downwardly from the first end of the shell to the opposite second end.

[0009] According to another aspect, the second end of the shell may define a substantially flat blunt surface.

[0010] According to another aspect, the cross-sectional surface of the shell may form one of a substantially hexagonal shape and a substantially octagonal shape along the length of the shell extending between the first and second ends.

[0011] According to a further aspect, the cross-section of the first end of the shell is larger than the cross-section of the second end.

[0012] According to yet another further aspect, the shell is comprised of plastic.

[0013] According to another aspect, the shell may define a plurality of apertures extending between the interior of the shell and the exterior of the shell.

[0014] According to another aspect, the shell may be substantially cylindrical in shape or substantially conical in shape.

[0015] According to a further aspect, the method can include positioning the shell on the ground and filling at least a portion of the interior of the shell with the particulate construction material. The particulate construction material can be consolidated in the interior of the shell to form the pier.

[0016] According to another aspect, the method may comprise forming a cavity in the ground. The cavity may be partially backfilled with the aggregate construction material. Next, the shell may be positioned with at least a portion of the interior of the shell filled with the cavity and particulate construction material. The particulate construction material can then be consolidated in the interior of the shell to form the pier. Consolidation can be performed on the primary mandrel. And additional consolidation may be performed with a second mandrel having a larger cross-sectional area than the main mandrel.

[0017] According to a further aspect, the expandable shell may comprise a plurality of slots extending between the interior of the shell and the exterior of the shell, the slots generally transverse to the centerline along the length of the shell. The slots are discontinuous about the circumference of the shell, thereby maintaining continuity of continuous material portions along the length of the shell. The slots may have a width in the range of 1/4 inch (6.35 mm) to 3/8 inch (9.53 mm), and may be spaced 6 inches (152 mm) apart from each other.

[0018] According to yet a further aspect, the present disclosure is directed to an extensible shell for constructing a support pier on the ground, wherein the expandable shell is configured to hold a granular construction material Wherein the expandable shell defines a first end having a first opening for receiving particulate construction material therein and a second end having a second opening, wherein the shell defines a particulate construction So that the shell expands laterally outwardly when the material is compacted.

[0019] In another aspect, the first end defines a first opening in a condition that the shell is shaped to taper from the first end to the opposite second end of the shell and the second end comprises the second opening.

[0020] In another aspect, a method is disclosed for constructing a support bridge in a ground, the method comprising the steps of positioning an expandable shell on a ground, the shell defining an interior for retaining particulate construction material, Defining a first opening at a first end and a second opening at a second end for receiving the interior of the shell, the shell being configured to allow the shell to expand laterally outward when the particulate construction material is consolidated within the shell - Eligible to do; Filling at least a portion of the interior of the shell with particulate construction material; And consolidating the particulate construction material within the shell to form a support pier.

[0021] In a further aspect, the present disclosure is directed to a method for constructing a support pier in a ground, the method comprising: forming a cavity in the ground; Partially refilling the cavity with the aggregate construction material; Positioning the expandable shell in a cavity, the shell having a first end having a first opening and a second end having a second opening, the shell defining an interior for retaining the particulate construction material, Wherein the shell is flexible such that when the particulate construction material is consolidated within the shell, the shell expands; Filling at least a portion of the interior of the shell with particulate construction material; And consolidating the particulate construction material within the shell to form a support pier.

[0022] This brief description is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description of the Invention. This brief description of the invention is not intended to identify key or essential features of the claimed subject matter nor is it intended to be used as a limitation on the scope of the claimed subject matter. Further, the claimed subject matter is not limited to implementations that solve any or all problems mentioned in any part of this disclosure.

[0023] FIGS. 1A, 1B, 1C, 1D, and 1E illustrate different views of an expandable shell in accordance with an embodiment of the present invention.
[0024] Figures 2a, 2b, and 2c illustrate steps of an exemplary method of constructing a bridge in a ground using an expandable shell in accordance with an embodiment of the invention.
[0025] Figures 3a, 3b, 3c, and 3d illustrate steps of another exemplary method of constructing a support pier in a ground using an expandable shell in accordance with embodiments of the present invention.
[0026] Figures 4, 5, 6, and 7 are graphs showing the results of load tests of support piers constructed using an expandable shell in accordance with embodiments of the present invention.
[0027] FIG. 8 illustrates a perspective view of another embodiment of the present invention with respect to a slotted shell.
[0028] FIG. 9 is a graph illustrating the results of load tests of support piers constructed using the embodiment shown in FIG.
[0029] Figures 10a and 10b illustrate an example perspective view and a cross-sectional view of an open-ended expandable shell in accordance with embodiments of the present invention.
[0030] Figures 11a, 11b, and 11c illustrate perspective and cross-sectional views of another example of an open-ended expandable shell in accordance with embodiments of the present invention.
[0031] Figures 12a and 12b illustrate an example of a process for installing an open-ended expandable shell on the ground.
[0032] FIG. 13 shows another example of installing an open-end expanded shell on the ground.
[0033] Figure 14 shows a flow diagram of an example of a method of using an open-ended expandable shell to form a support pier.
[0034] Figures 15a and 15b illustrate certain process steps using an open-ended expandable shell to form a pier.
[0035] FIG. 16 is a graph illustrating the results of load tests of support piers constructed using the embodiment shown in FIGS. 10a, 10b, and / or 11a, 11b, and 11c.

[0036] The present invention relates to an expandable shell and associated methods for constructing a support "shell pier" on the ground. In particular, the expandable shell according to embodiments of the present invention may have an interior that can be loaded and consolidated in particulate construction material. The shell may be positioned in a cavity formed in the ground (the cavity is formed through various methods, as described in more detail below, including plugging the shell from the grade to form the cavity). After positioning on the ground, the particulate construction material can be loaded internally through the opening in the shell. The particulate construction material can subsequently be consolidated. The shell may be expandable (or flexible) such that the walls of the shell expand when the particulate construction material is consolidated within the shell. Thus, because the shell keeps the consolidated particulate construction material in a contained manner (i.e., the material can not expand laterally into the field generated over the shell walls), the ground surrounding the shell is shallow Reinforced and improved to support bases and other structures. The present invention may be advantageous, for example, because the particulate construction material allows much higher load bearing capacity due to its ability to limit side bulging to the outside during charging. The shell is typically made of a relatively permanent, substantially non-corrosive and / or non-degradable material such that lateral inflation of the material is limited during the lifetime of the pier.

[0037] 1A-1E illustrate different views of an expandable shell 100 in accordance with embodiments of the present invention. FIG. 1A depicts a perspective view of an expandable shell 100 including an enclosed end 102. FIG. The surface of the enclosed end 102 may define a substantially planar, blunt bottom surface 104 that may be hexagonal in shape. Alternatively, the enclosed end 102 may have any other suitable shape or size. The bottom of the shell may also be open or may be blunt as in the case of a cylindrical shell or may be pointed like the bottom of a conical shell or may be frustum or frustum, May be truncated to form a blunt configuration at the bottom of a conical or articulated section such as a frustoconical configuration. Thus, for purposes of this disclosure, the term cone is understood to include cone configurations. The length of the shell may range from about 0.5 m to about 20 m in length; For example, from about 1 m to about 10 m in length. The surfaces of the shell (interior and / or exterior) may be smooth or may include varying degrees of roughness for interaction with surrounding surfaces.

[0038] Opposing the encapsulated end 102 is the other end defining an opening 108 for receiving the granular construction material into the interior defined by the shell 100 Open end. As will be described in greater detail herein below, the open end 106 is positioned substantially vertically and from the end to the end 102 enclosed during the construction of the pier.

[0039] Figures 1B, 1C, 1D, and 1E depict a top view, a bottom view, a side view, and a cross-sectional side view, respectively, of the expandable shell 100. 1B, the expandable shell 100 includes a substantially hollow interior 110 extending between the open end 106 (with the opening 108) and the enclosed end 102 And

[0040] 1C shows that the cross-section of the open end 106 can be formed larger than the bottom surface 104 of the enclosed end portion 102. FIG. FIG. 1D shows cross-sectional lines A-A in the direction of the cross-sectional view of the expandable shell 100 depicted in FIG.

[0041] The external shape of the shell 100 may be articulated so as to form a plurality of panels that form a hexagonal shape when viewed from the top or bottom of the shell. Alternatively, the shape may be octagonal, cylindrical, conical, or any other suitable shape.

[0042] The expandable shell 100 is often shaped to taper downwardly from the open end 106 to the sealed end 102. In one embodiment, the shell 100 tapers at a two degree angle, but the shell may taper at any other suitable angle.

[0043] The expandable shell 100 may be made of plastic, aluminum, or any metallic or non-corrosive material of suitable extensibility, and preferably substantially non-corrosive and / or non- - can be made of metallic material. Shell 100 may be a relatively thin wall. The wall thickness of the shell 100 may range, for example, from about 0.5 mm to about 100 mm. The exemplary shell 100 of FIG. 1B has a thickness of about 0.25 inches (about 6.35 mm), but the shell may have any other suitable thickness. The thickness interval is an interval for uniformly separating the inside (110) of the shell and the outside. The material and thickness of the shell may be configured to have proper integrity such that the shell retains the construction material in its interior 110 and expands laterally at least a slight distance when the construction material is consolidated in the interior 110 .

[0044] 2A-2C illustrate steps of an exemplary method of constructing a bridge in a ground using the expandable shell 100 according to an embodiment of the present invention. In this example, partial lateral cross-sections illustrate the use of an expandable shell 100 (see FIG. 2C) for building a pier 200 in a ground according to an embodiment of the present invention. Other methods are described with reference to Figures 3a to 3d and the following examples. The method of Figures 2a-2c includes the steps of forming a pre-formed elongate vertical cavity 202 or hole in the ground surface 204, as shown in Figure 2a, . The ground may consist mainly of soft cohesive soils such as soft clay and silt or loose sand and fill materials. have. The cavity 202 may be formed, for example, with a suitable drilling device having a drill head or auger to form a cavity or hole, or may be formed, for example, with a driving mandrel ≪ / RTI > may be formed by other methods of forming cavities by insertion and removal. In some embodiments, the cavity may not be formed at all before shell insertion, as described below with reference to Figures 3A-3D.

[0045] After the partial cavity 202 is formed, the expandable shell 100 can be positioned within the cavity 202 to finally reach the desired depth, as shown in FIG. 2B. In particular, an extractable mandrel 206 may be used to enclose the expandable cell 100 in the cavity 202 and the ground 204. The tamper head 208 of the mandrel 206 can be positioned to abut the bottom surface 210 of the interior 110 as shown in Figure 2C and the shell 100 can be positioned at a desired penetration depth . Cavity 202 is sized and sized to fits tightly against the walls of cavity 202 at the point where the outer surface of expandable shell 100 is fits tightly.

[0046] After the expandable shell 100 is embedded in the sufficiently enlarged cavity 202, the mandrel 206 is removed and the shell 100 is left in the cavity 202 and the interior 110 is empty. The shell 100 may then be treated with a particulate material such as sand aggregate, admixture-stabilized sand or aggregate, recycled materials, crushed glass, or other suitable materials, May be filled with construction material (212). The particulate construction material 212 may be compacted within the shell using the mandrel 206. Compaction increases the strength and stiffness of the inner particulate construction material 212 and pushes the particulate construction material 212 against the walls of the shell 100 and pushes it outwardly,

This pre-strains the shell 100 and increases the coupling of the shell 100 with the on-site soil. Significant increases in the load carrying capacity of the bridge 200 can be obtained as a result of the restraint provided by the shell 100.

[0047] Figures 3A-3D illustrate steps of another exemplary method of constructing a bridge in a ground using an expandable shell in accordance with an embodiment of the present invention. 3A, an aggregate construction material 300 (e.g., sand) is disposed to a predetermined level above the bottom surface 210 of the shell 100 in the interior 110 of the shell 100. As shown in FIG. The tamper head 208 of the extractable mandrel 206 then fits into the interior 110 of the expandable shell 100 and over the top of the aggregate construction material 300. The mandrel 206 may then be moved toward the ground 204 in the direction indicated by the arrow 302 to place the shell 100 in the ground 204. Stamping may or may not be facilitated using a preformed small cavity (e.g., cavity 202 shown in FIG. 2A), depending on field conditions.

[0048] Referring to FIG. 3B, the mandrel 206 is shown in the direction of putting the shell 100 into the ground 204 in the direction 302 so that the shell 100 is at a predetermined depth below the grade. Next, the mandrel 206 can be removed. 3C, shell 100 is substantially filled with additional aggregate construction material 304 (e.g., sand) through opening 108 and mandrel 206 is positioned as shown. Next, vertical consolidation force and / or vibrational energy is applied to the mandrel 206 to consolidate the materials 300 and 304. The shell 100 can be stuck to a depth further downward by this force. The addition of construction material 304 and subsequent consolidation can be repeated several times until the final bridge is built. Alternatively, the shell may be "topped off " with additional construction material after only one consolidation cycle.

[0049] In one embodiment of the present invention, the second mandrel 212 can be used to consolidate the upper portion of the material 304 in the direction 302, as shown in Figure 3D. The second mandrel 212 may have a larger cross-sectional area than the primary mandrel 206 to provide increased confinement during consolidation.

[0050] The shell 100 may define apertures 218 extending to the in-situ soil between the interior 110 and the exterior of the shell 100 (see, for example, 1A and 2C). The apertures 218 may provide a multiple of excess pore water pressure that may be present in the on-site generated soil to drain into the interior 110 of the shell 100. Increases in pore water pressure typically reduce the strength of the soil, which is one of the reasons that prior art piers are limited in their load bearing capacity in saturated clays such as clay, silt, and the like. The projected apertures 218 herein allow the excess pore water pressure of the soil to dissipate into the pier 200 after insertion. This allows the on-site artefact to gain strength quickly over time and allows unrecoverable phenomena by concrete, steel files, or grout elements (i.e., "cured" elements). A multiple of excess pore water pressure allows for additional settlement of the soil that can occur as a result of pore water pressure dissipation prior to applying foundation loads.

[0051] Other embodiments may not define the apertures, or may provide one or more apertures 218 on only one side of the shell 100. Alternatively, the apertures 218 can be positioned along a portion of the length of the shell 100, positioned along the entire length of the shell 100, or positioned asymmetrically in various configurations, 100). The sizes and arrangements of the apertures 218 may vary depending on the size of the shell 100, the conditions of the ground (e.g. where the higher water pressure is known to be present) and other relevant factors. The apertures 218 may have a width of about 0.5 mm to about 50 mm; For example, it can range in size from about 1 mm to about 25 mm. In another embodiment, the upper portion of the shell 100 may be connected via apertures 218 surrounded by a vacuum pressure to further increase and accelerate the surplus water pressure in the surrounding soil.

[0052] The mandrel 206 may be constructed with sufficient strength, rigidity, and geometry to allow the shell 100 to be properly retracted and retracted from the shell 100 after being struck. In one embodiment, the external shape of the mandrel 206 is substantially similar to the shape of the interior 110 defined by the shell 100. In another embodiment, the mandrel 206 is comprised primarily of steel. Also contemplated are other materials including, but not limited to, aluminum, rigid composites, and the like.

[0053] The mandrel 206 is a piling machine capable of applying a static crowd pressure, hammering or vibration sufficient to engage the mandrel 206 and the expandable shell 100 on the surface of the ground 204 a piling machine or other suitable equipment and techniques. In one embodiment, the machine may be comprised of an articulating, diesel, pile-driving hammer that jacks the mandrel 206 using high energy impact forces. The hammer can be mounted on the hanging leads from the crane. In another embodiment, the hammer may be a sheet pile vibrator mounted on a rig capable of providing a downward static force. In another embodiment, the shell 100 may be disposed in the prefabricated cavity 200 and constructed without the use of an extractable mandrel. Standard methods of putting mandrels on the ground are known in the art and can therefore be used for jacking.

[0054] The following examples illustrate further aspects of the invention.

Example I

[0055] By way of example, the piers were constructed using extended shells in accordance with embodiments of the present invention at a testing site in Iowa. Load tests were performed on the bridges using conventional processes. The extended shells used in the tests and their methods of use were essentially constructed as described above and shown in the accompanying drawings. In this test, expandable shells made of LEXAN® polycarbonate plastic were installed in a test site featuring soft clay. This test was designed to compare the load versus deflection characteristics of an expandable shell according to the present invention to aggregate piers constructed using a driven tapered pipe. Two comparative framed bridges (fine aggregate and coarse aggregate) were constructed at a depth of 12 feet below the ground.

[0056] In this test, an expandable shell was formed by bending the sheets of plastic to form a tapered shape with a hexagonal cross-section, which was 18 inches (460 mm) from the bottom of the shell from an outer diameter of 24 inches (610 mm) ). ≪ / RTI > The panels of the shells were overlapped, and this part was glued together and bolted together. The length of the extended shell was 9.5 feet (2.9 m). In this embodiment, the apertures were formed in the expandable shell by punching the sides of the shell with "weep" holes of 3 mm to 7 mm diameter spaced apart from one another. The bottom of the shell was capped with a steel shoe to facilitate putting. LEXAN® polycarbonate plastic has a tensile strength of approximately 16 MPa (2300 psi) at 11% elongation and Young's modulus of 540 MPa (78,000 psi). The extractable mandrels used in this test were attached to the high frequency hammer, which is often associated with putting sheet files. The hammer can provide both downward force and vibration energy to compact the aggregate construction material into the shell and to shell the shell.

[0057] In this example, the expandable shell was embedded in the ground without pre-drilling cavities or holes. Specifically, in this test, the two shells orient each shell in a vertical direction, place approximately four feet (1.2 m) of sand in the base of the shell, and then place the outer Lt; RTI ID = 0.0 > a < / RTI > extractable mandrel having dimensions. The shell was embedded at a depth of approximately 8.5 feet (2.6 meters) below the grade. The mandrel was removed and the shells were filled with sand. The extractable mandrel was then re-lowered in the shells and in conjunction with the oscillating energy a vertical consolidation force was applied to consolidate the sand and the shell was moved to a depth of 9 feet (2.7 m) below the grade . The mandrel was then extracted, and the upper portion of the shell was then filled with crushed stone to a depth of 0.5 feet (0.2 m) below the grade. The concrete cap was then poured over the crushing filler to facilitate the load test.

[0058] Radial cracks were observed extending from the edge of the shell pier to the outer chamber. These cracks form drainage galleries which result in high radial stresses and low tangential stresses created in the ground during pier installation. The drainage was allowed by the perforations of the shell and drainage water was allowed to drain into the piers filled with sand and aggregate.

[0059] The shell piers were subjected to a load test using a hydraulic jack pushing against the test frame. Figure 4 is a graph showing the results of a load test in comparison with aggregate piers constructed using a similar shaped mandrel. As shown in FIG. 4, at the top of the 1 inch pier deflection, the piers built without shells supported loads of 15,000 to 20,000 pounds (67 kN to 89 kN). The shell piers constructed in this embodiment of the present invention supported loads of 310 kN to 360 kN (70,000 pounds to 80,000 pounds) at the top of the 1 inch piercing sag. The load bearing capacity of the shell piers constructed in accordance with the present invention provided an improvement of 3.5 to 5.3 times compared to the aggregate piers constructed without the expandable shells.

Example II

[0060] In another test, expandable shells were formed of high density polyethylene polymer ("HDPE") and installed in a test location as described in Example I. This test program was designed to compare the load versus deflection properties of this embodiment of the present invention with aggregate piers constructed using a tapered pipe as described in Example I. A total of six shell piers were installed as part of this example.

[0061] In this test, the expandable shell was formed by a rotomolding process. The shells defined a tapered shape with a hexagonal cross-section, which tapered down to a diameter of 460 mm (18 inches) from the bottom of the shell from an outer diameter of 585 mm (23 inches) at the top of the shell. The bottom of the expandable shell was integrally constructed as part of the shell walls as a result of the rotational molding process. The mandrel of this example was attached to the same hammer as described in Example I.

[0062] The installation process of this embodiment was somewhat different from the installation process in Example I (not initially shelling from the upper grade) and down the ground to a depth of 2 inches (0.61 m) to 3 feet (0.9 m) 0.76 m) diameter cavities. The shell was then placed vertically in the pre-drilled cavity. The extractable mandrel was then inserted into the shell and the shell was embedded down to a depth of 11 feet (3.4 m) to 12 feet (3.7 m) below the grade. The expandable shell was then filled with aggregate construction material and consolidated with four lifts (each lift having a volume of about 7.4 square feet (0.2 square meters)). The aggregate consisted of sand in five of the piers, and one of the piers consisted of crushed stone. Each lift was consolidated with the downward pressure and vibrational energy of the extractable mandrel.

[0063] After sand placement and consolidation within the expandable shells, the tops of the shells were positioned about 2 feet (0.61 m) to 3 feet (0.9 m) below the ground. A crushed stone was then placed over the expanded shell at a depth of 1 foot (0.3 m) below ground and consolidated. The concrete cap was then poured onto the crushing filler to facilitate the load test.

[0064] The shell piers were subjected to a load test using a hydraulic jack pushing against the test frame. 5 is a graph showing the results of a load test compared to the aggregate piers described in Example I. FIG. As shown in FIG. 5, at the top of the 1 inch pier deflection, the piers constructed without shells supported loads of 15,000 to 20,000 pounds (67 kN to 89 kN). The shell piers constructed in this embodiment of the present invention supported loads in the range of 62,000 pounds (275 kN) to 71,000 pounds (315 kN) at the top of the 1 inch piercing sag. The load bearing capacity of the shell piers constructed in accordance with this embodiment of the present invention provided an improvement of 3.1 to 4.7 times compared to the aggregate piers constructed without the expandable shells.

Example III

[0065] In another test, an expandable shell of the same embodiment described in Example II was installed in a test location as described in Example I. This test program was designed to compare the load versus deflection properties of this embodiment of the present invention with aggregate piers constructed using a tapered pipe as described in Example I. The mandrels, hammers, and expandable shells used in the test were the same as those used in Example II.

[0066] In this embodiment of the invention, the installation process previously drilled a 30 inch (0.76 m) diameter cavity down to 3 feet (0.9 m) depth below the ground. Cavities with a total depth of 5 feet (1.5 m) were then created downward when the extractable mandrel was inserted into the pre-drilled cavity. Then, this cavity was backfilled with sand. The expandable shell was then placed vertically to a depth of 9 feet (2.7 m) below the ground with the extractable mandrel through a sand filled cavity, with the top of the shell positioned 6 inches above the ground. The expandable shell was then filled with sand in four lifts (each lift having a volume of about 7.4 square feet (0.2 square meters)). Each lift was consolidated with the downward pressure and vibration energy of the mandrel. The concrete cap surrounding the top of the shell was then cast onto the shell to facilitate loading testing.

[0067] The shell piers were subjected to a load test using a hydraulic jack pushing against the test frame. FIG. 6 is a graph showing the results of a load test in comparison with the aggregate piers described in Example I. FIG. As shown in FIG. 6, at the top of the 1 inch pier deflection, the piers constructed without shells supported loads of 15,000 to 20,000 pounds (67 kN to 89 kN). The piers constructed in this embodiment of the present invention supported a load of 57,500 pounds (255 kN) at the top of the 1 inch piercing sag. The load bearing capacity of a shell pier constructed according to this embodiment of the present invention provided an improvement of 2.9 to 3.8 times compared to aggregate piers built without an expandable shell.

Example IV

[0068] In another test, an embodiment of the present invention is a method of forming a 3 foot (0.9 m) non-compacted sand on 7 foot (2.1 m) soft clay soil on a dense sandy soil It was installed in a project site featuring. An embodiment of the invention at the project site has been used to support structural loads such as building foundations and structural loads associated with heavily loaded floor slabs. The mandrels, hammers, and expandable shells used for testing were the same as those used in Examples II and III.

[0069] In this embodiment of the invention, the installation process previously drilled a 30 inch (0.76 m) diameter pre-drill to a depth of 3 feet (0.9 m) below the ground. Approximately 7.4 square feet (0.2 square meters) of sand were then placed in the pre-drilled cavity. This has led to pre-drilled cavities being approximately half-full.

[0070] The expandable shell was then placed vertically in the partially drilled backfilled cavity. The extractable mandrel was then inserted into the shell, and the shell was embedded down to a depth of 12.5 feet (3.8 m) below the grade. The expandable shell was then filled with sand in four lifts (each lift having a volume of about 7.4 square feet (0.2 square meters)). Each lift was consolidated with the downward pressure and vibration energy of the mandrel.

[0071] After sand placement and consolidation within the expandable shell, a lift of about 4.9 square feet (0.14 square meters) of crushed stone was placed in the expanded shell and consolidated. The crushed stone was then placed and consolidated in the expanded shell until the crushed stone backfill was at the same level as the ground.

[0072] At one shell location, a 30-inch (0.76 m) diameter concrete cap was placed on the shell to facilitate load testing. At a second shell location, a concrete cap having a width of 6 ft (1.8 m) x 6 ft (1.8 m) in width facilitates loading and allows the use of a composite of a natural matrix soil and an expandable shell It was placed on the shell to simulate load deflection characteristics (to simulate a floor slab).

[0073] The shell piers were subjected to a load test using a hydraulic jack pushing against the test frame (the results of the load test are shown in FIG. 7). The shell pier, which was tested with a 30-inch diameter concrete cap, supported a load of 35,500 pounds (158 kN) at a deflection of 0.4 inches (10 mm). The shell pit tested with a concrete cap of 6 feet wide and 6 feet wide supported a load of 104,700 pounds (467 kN) at a deflection of 0.4 inches (10 mm).

Slotted shell embodiment

[0074] 8, there is shown an alternative embodiment of the present invention which includes an expandable shell 800 having one or more slits or slots 812 extending between the interior of the shell and the exterior of the shell do. The slots 812 may be located over the entire length of the shell 800 or may be located only partially along the length and may have variable spacing, e.g., (0.46 m) and spaced every 6 inches (152 mm). The slots 812 may be variable widths, such as, for example, 1/4 inch (6.35 mm) to 3/8 inch (9.53 mm) widths. The slots 812 typically extend generally across the centerline along the length of the shell and may form a major or minor portion of the circumference of the shell 800. [ 8, the slots 812 are discontinuous about the circumference to form three spines (not shown) to maintain continuity of continuous material portions along the length of the shell 800. In one embodiment, 814). The shell 800 of the present embodiment may be any suitable size or shape as described above with reference to the shell 100.

[0075] By way of example, the slotted, expandable shell of the present embodiment may be used to compare the load versus deflection characteristics of this embodiment of the expandable shell to the aggregate piers constructed using the tapered tapered pipe in a test location in Iowa Installed. The test site was characterized by soft clay soil and two comparative aggregate piers (fine aggregate and coarse aggregate) were constructed at a depth of 12 feet below the ground.

[0076] For testing of this expandable shell, the shell was formed of a high density polyethylene polymer and formed by a rotational molding process. The shell was hexagonal in cross section and formed a tapered shape that tapered down from the outer diameter of 23 inches (585 mm) at the top of the shell to the diameter of 18 inches (460 mm) at the bottom of the shell. The bottom of this embodiment of the expandable shell was integrally constructed as part of the shell walls as a result of the rotational molding process. In this embodiment of the invention (similar to the embodiment shown in FIG. 8), 1/4 inch (6.35 mm) wide slots were cut in circumferential orientation around the expandable shell. The expandable shell was left as one continuous piece by not removing material from three of the six corners or spines. The extractable mandrels used in this test were attached to the high frequency hammer, which is often associated with putting sheet files. The hammer can provide both downward force and vibration energy to compact the aggregate construction material into the shell and to shell the shell.

[0077] In this example, the installation process included a 30 inch (0.76 m) diameter pre-drill to a depth of 1.5 feet (0.46 m) below ground. The shell was then placed perpendicular to the pre-drilled hole, and then the shell was embedded into an extractable mandrel having external dimensions similar to the internal dimensions of the shell. The shell was embedded down to a depth of 11 feet (3.4 m) below the grade. The mandrel was removed, and then the expandable shell was filled with aggregates in four lifts (each lift having a volume of about 7.4 square feet (0.2 square meters)). Each lift was consolidated with the downward pressure and vibrational energy of the extractable mandrel.

[0078] After placing and consolidating the aggregate within the expandable shell, the top of the shell was positioned about 1.5 feet (0.46 m) below the ground. The backfill of the aggregate was then at the same level as the top of the shell, and then the concrete cap was poured onto the shell to facilitate loading testing.

[0079] The slotted shell piers were subjected to a load test using a hydraulic jack that pushed against the test frame. 9 is a graph showing the results of the load test as compared with the aggregate pier described above. As shown in FIG. 9, on top of a 1 inch pier deflection, piers built without slotted shells supported a load of 15,000 pounds to 20,000 pounds (67 kN to 89 kN). The piers constructed in this embodiment of the present invention supported a load of 77,500 pounds (345 kN) at the top of the 1 inch piercing sag. The load bearing capacity of a pier constructed in accordance with this embodiment of the present invention provided an improvement of 3.9 to 5.2 times compared to aggregate piers constructed without extended shells.

An open-end embodiment

[0080] Referring to Figs. 10A-B, an alternative embodiment of the present invention is shown, which includes an open-ended expandable shell that can be used to form the piers. 10A shows a perspective view of an example of the open-ended expandable shell 1000. As shown in FIG. Figure 10B shows a cross-sectional view of the open-end expanded shell 1000 taken along line A-A in Figure 10A. In this example, the open-ended expandable shell 1000 is a hollow tubular member having a first open end 1010 and a second open end 1012. The open-ended expandable shell 1000 can be used in any orientation for putting on the ground. However, for purposes of illustration, the first open end 1010 is hereinafter referred to as an advancing open end 1010, wherein the open front end 1010 is initially an open-ended expandable shell 1010 that is advanced into the ground, Quot; bottom end " The second open end 1012 is hereinafter also referred to as a trailing open end 1012 wherein the subsequent open end 1012 is an open end 1012 that mates with driving equipment such as a mandrel, Which means the upper end of the expandable shell 1000.

[0081] The open-ended expandable shell 1000 can be of any length and any width or diameter. Without limitation, the length of the open-ended expandable shell 1000 may be from about 3.05 m (5 ft) to about 6.1 m (20 ft) in one example, or about 10 ft (3.05 m) in another example . Without limitation, the width or diameter of the open-ended expandable shell 1000 can be from about 61 cm (24 in.) To about 46 cm (18 in.) In one example, or about 20.4 in. . In one example, the open-ended expandable shell 1000 may be formed of a plastic such as a high density polyethylene polymer (HDPE) plastic. In another example, the open-ended expandable shell 1000 may be formed of a metal such as steel or aluminum.

[0082] The open-ended expandable shell 1000 is not limited to a straight tubular shape. For example, FIGS. 11A, 11B, and 11C illustrate various views of an example of an open-ended expandable shell 100 having a hexagonal cross-section and a tapered tip; That is, the open end 1010 tapers. 11A and 11B illustrate perspective views of a portion of the front open end 1010 of the open-ended expandable shell 1000, which is hexagonal and includes a taper 1020. FIG. 11C shows a cross-sectional view of the open-end expanded shell 1000 taken along line B-B of FIG. 11B. In one example, the width or diameter of the open-ended expandable shell 1000 is tapered from about 20.4 inches to about 46 inches (18.1 inches).

[0083] 12A and 12B illustrate an example of a process for installing an open-ended expanded shell 1000 into a ground (e.g., ground 1205). In this example, a closed pipe mandrel 1210 with a shoulder collar 1215 is used to fasten the open-ended expandable shell 1000 to the ground 1205. The closed collar mandrel 1210 is inserted into the open-ended expandable shell 1000 until the shoulder collar 1215 contacts the subsequent open end 1012 of the open-ended expandable shell 1000. Thus, a driving force is transmitted from the closed pipe mandrel 1210 to the open-end expanded shell 1000. 12A and 12B, the front end of the closed pipe mandrel 1210 extends beyond the forward open end 1010 of the open-ended expandable shell 1000. In one example, the end of the closed pipe mandrel 1210 extends about 5 m (5 ft) beyond the front open end 1010 of the open-ended expandable shell 1000.

[0084] However, the position of the shoulder collar 1215 may be adjustable along the length of the closed pipe mandrel 1210. That is, the shoulder collar 1215 may be adjustable so that the depths of the open-ended expanded shell 1000 and the closed pipe mandrel 1210 and the range of relative positions can be obtained without having to change the mandrels. For example, FIG. 13 illustrates the location of the shoulder collar 1215 that is configured to substantially align while the forward end of the closed pipe mandrel 1210 advances the open end 1010 of the open-ended expandable shell 1000.

[0085] 14 shows a flow diagram of an example of a method 1400 of using an open-ended expandable shell 1000 to form a support pier. Method 1400 may include, but is not limited to, the following steps.

[0086] In step 1410, the open-ended expanded shell 1000 is stuck to the surface using a mandrel. For example, referring again to FIGS. 12A and 12B, the open-ended expanded shell 1000 is embedded in the ground 1205 using a closed pipe mandrel 1210.

[0087] In step 1415, a mandrel (e.g., a closed pipe mandrel 1210) is withdrawn from the open-ended expandable shell 1000 leaving the open-ended expanded shell 1000 in the ground. For example, FIG. 15A illustrates an open-ended expanded shell 1000 of a ground 1205 creating a shell cavity 1220 after a closed pipe mandrel 1210 has been drawn. That is, the shell cavity 1220 is part of the material-free ground 1205.

[0088] In step 1420, the shell cavity 1220 is refilled with sand, aggregate, cementitious grout, and / or any other material. For example, FIG. 15B illustrates a shell cavity 1220 of an open-ended expandable shell 1000 that is re-filled with the volume of material 1225.

[0089] In step 1425, a mandrel (e.g., a closed pipe mandrel 1210) is reinserted into the open-ended expandable shell 1000. The material 1225 is then packed under the forward open end 1010 of the open-ended expandable shell 1000. For example, Figure 15B illustrates that a "bulb" of material 1225 is formed in the ground 1205 below the forward open end 1010 of the open-ended expandable shell 1000. [

[0090] In step 1430, the mandrel (e.g., the closed pipe mandrel 1210) is again withdrawn from the open-ended expandable shell 1000, as shown in FIG. 15A.

[0091] In step 1435, the remainder of the shell cavity 1220 is refilled with a material 1225 (e.g., sand, aggregate, cementitious grout, and / or any other material).

[0092] In step 1440, a mandrel (e.g., a closed pipe mandrel 1210) is reinserted into the open-ended expandable shell 1000. The material 1225 is then filled into the shell cavity 1220 of the open-ended expanded shell 1000.

[0093] At step 1445, the mandrel (e.g., the closed pipe mandrel 1210) is again withdrawn from the open-ended expandable shell 1000, as shown in FIG. 15A.

[0094] In decision step 1450, it is determined whether construction of the support pier has been completed. Once construction of the support pier has been completed, the method 1400 ends. However, if the construction of the support pier has not been completed, the method 1400 returns to 1435.

[0095] An advantage of using the open-ended expandable shell 1000 and method 1400 is that the increased stiffness for the shell support layer and the increased overall length of the expandable shell system in the upper zone (open-ended expandable shell 1000 + "Bulb" depth).

Yes V

[0096] As an example, support piers were constructed using extended shells in accordance with embodiments of the present invention at a test site in Iowa. Load tests were performed on the bridges using conventional processes. The extended shells used in the tests and their methods of use were essentially constructed as described above and shown in Figures 10a-15b. In this test, an expandable shell formed of high density polyethylene polymer (HDPE) plastic was installed in a test site characterized by soft clay soil. This test was designed to compare the load versus deflection characteristics of an expandable shell according to the present invention to aggregate piers constructed using a driven tapered pipe. Two comparative aggregate piers were constructed at a depth of 12 feet below the ground.

[0097] In this test, the expandable shell was formed by a rotomolding process. The shells defined a tapered shape with a hexagonal cross-section (e.g., as shown in Figs. 11A, 11B, and 11C), which was obtained from an outer diameter of 518 mm (20.4 inches) at the top of the shell And tapered down to a diameter of 460 mm (18.1 inches). In the present embodiment of the invention, the expandable shell has an overall length of 10 ft., And is designed so that an extractable tapered mandrel commonly used for constructing aggregate piers can pass completely through the expandable shell. Both the top and bottom ends are open.

[0098] The extractable mandrels used in this test were attached to the high frequency hammer, which is often associated with putting sheet files. The hammer can provide both downward force and vibration energy to compact the aggregate construction material into the shell and to shell the shell. The "open bottom" extended shell piers and aggregate piers were constructed with similar mandrels and high frequency hammers.

[0099] In this example, a pre-drilled hole with a diameter of 61 inches (24 in) and a depth of 61 inches (24 in) was formed on the ground prior to deployment of the expandable shell. The purpose of the pre-drill is to facilitate the placement of the concrete cap for load testing. The expandable shell and tapered mandrel are then positioned such that the tip of the tapered mandrel is at a depth of about 5.2 ft (17 ft) below the ground and the bottom of the expandable shell is about 12 feet (3.65 m) below the ground And the top of the shell was embedded in the ground to a depth of about 61 cm (24 in) below the ground.

[00100] The tapered mandrel used in this example is hollow to allow the mandrel to be filled with the aggregate and to flow out of the bottom of the mandrel. By raising and lowering the mandrel at predetermined intervals to build an aggregate pier, an aggregate pier is built into the mandrel. In this example, an aggregate pier was constructed under and within the expandable shell using a similar process.

[00101] The open bottom expanded shell piers were subjected to a load test using a hydraulic jack pushing against the test frame. FIG. 16 is a graph showing the results of a load test in comparison with aggregate piers constructed using the embodiment shown in FIGS. 10A, 10B, and / or 11A, 11B, and 11C. As shown in FIG. 16, at the top of the 1-inch bridge sag, the piers constructed without shells supported loads of 67 kN to 89 kN (15,000 pounds to 20,000 pounds). The piers constructed in this embodiment of the present invention supported a load of 188 kN (42,300 pounds) at the top of the 1 inch pit deflection. The load bearing capacity of the piers constructed in accordance with the present invention provided an improvement of 2.1 to 2.8 times compared to the aggregate piers constructed without the expandable shells.

[00102] The foregoing detailed description of the embodiments refers to the accompanying drawings which illustrate specific embodiments of the invention. Other embodiments having different structures and operations are within the scope of the present invention. The terms "invention" and the like are used herein to refer to many alternative aspects or embodiments of the inventions of the applicant as presented herein, and the absence of the absence is not intended to limit the scope of the inventor's invention Neither the uses nor the absence of which is intended to limit the scope. Moreover, although the term "step" which may be used herein may be used to imply different aspects of the methods in use, it will be understood that the term And should not be construed as implying any particular order between the various steps disclosed. This specification is divided into sections for your convenience only. The headings should not be construed as limiting the scope of the invention. It will be appreciated that various details of the invention may be varied without departing from the scope of the invention. Moreover, the foregoing description is for purposes of illustration only and not for the purposes of limitation.

Claims (32)

An extensible shell for constructing a support pier on the ground,
Said expandable shell defining a interior for retaining a granular construction material and having a first end having a first opening for receiving said particulate construction material therein and a second end having a second opening, And,
Wherein the shell is configured such that when the particulate construction material is consolidated within the shell, the shell expands laterally outwardly,
Expandable shell. The method according to claim 1,
Wherein the shell is shaped to taper downwardly from a first end of the shell to an opposite second end,
Expandable shell. 3. The method of claim 2,
Wherein the cross-section of the shell defines one of a substantially hexagonal shape and a substantially octagonal shape along the length of the shell extending between the first and second ends,
Expandable shell. 3. The method of claim 2,
Wherein the cross-section of the first end is sized larger than the cross-section of the second end,
Expandable shell. The method according to claim 1,
Wherein the shell is made of plastic,
Expandable shell. The method according to claim 1,
The shell defining a plurality of apertures extending between the interior of the shell and the exterior of the shell,
Expandable shell. The method according to claim 1,
The shell has a substantially cylindrical shape,
Expandable shell. The method according to claim 1,
The shell has a substantially conical shape,
Expandable shell. As a method for constructing a support pier on the ground,
(a) positioning an expandable shell on the ground, the shell defining an interior for retaining particulate construction material, defining a first opening at a first end for receiving the particulate construction material therein, and Defining a second opening at a second end, the shell being flexible to expand the shell when the particulate construction material is consolidated within the shell;
(b) filling at least a portion of the interior of the shell with the particulate construction material; And
(c) consolidating said particulate construction material within said shell to form a support pier.
A method for constructing support piers on the ground. 10. The method of claim 9,
Wherein the shell is shaped to taper downwardly from a first end of the shell to an opposite second end,
A method for constructing support piers on the ground. 11. The method of claim 10,
Wherein the cross-section of the shell defines one of a substantially hexagonal shape and a substantially octagonal shape along the length of the shell extending between the first and second ends,
A method for constructing support piers on the ground. 11. The method of claim 10,
Wherein the cross-section of the first end is sized larger than the cross-section of the second end,
A method for constructing support piers on the ground. 10. The method of claim 9,
Wherein the shell is made of plastic,
A method for constructing support piers on the ground. 10. The method of claim 9,
The shell defining a plurality of apertures extending between the interior of the shell and the exterior of the shell,
A method for constructing support piers on the ground. 15. The method of claim 14,
Further comprising applying a vacuum pressure through the shell,
A method for constructing support piers on the ground. 10. The method of claim 9,
The shell has a substantially cylindrical shape,
A method for constructing support piers on the ground. 10. The method of claim 9,
The shell has a substantially conical shape,
A method for constructing support piers on the ground. 10. The method of claim 9,
Wherein the positioning step of step (a) further comprises: partially filling the shell with the particulate construction material and driving the shell following the step of partially filling the shell.
A method for constructing support piers on the ground. 19. The method of claim 18,
The step of applying the expandable shell to the ground comprises applying a force to the mandrel to place the shell on the ground.
A method for constructing support piers on the ground. 10. The method of claim 9,
Wherein the step of locating the step (a) further comprises the step of forming a cavity in the ground first, and subsequently putting the expandable shell into the cavity.
A method for constructing support piers on the ground. 21. The method of claim 20,
Wherein the cavity is at least partially filled with particulate construction material after the forming step and prior to the step of inserting the expandable shell into the cavity,
A method for constructing support piers on the ground. 10. The method of claim 9,
Wherein the consolidating step of step (c) is carried out with a primary mandrel,
A method for constructing support piers on the ground. 23. The method of claim 22,
Further comprising a further consolidating step performed with a second mandrel having a cross-sectional area greater than the major mandrel,
A method for constructing support piers on the ground. As a method for constructing a support pier on the ground,
(a) forming a cavity in the ground;
(b) partially refilling said cavity with aggregate construction material;
(c) positioning the expandable shell in a cavity, the shell having a first end having a first opening and a second end having a second opening, the shell defining an interior for retaining particulate construction material Defines an opening for receiving said particulate construction material therein, said shell being flexible to expand the shell when the particulate construction material is consolidated within the shell;
(d) filling at least a portion of the interior of the shell with the particulate construction material; And
(e) consolidating said particulate construction material within said shell to form a support pier.
A method for constructing support piers on the ground. The method according to claim 1,
Further comprising a plurality of slots extending between the interior of the shell and the exterior of the shell, the slots generally extending across the length of the shell,
Expandable shell. 26. The method of claim 25,
Wherein the slots are discontinuous about a circumference of the shell, thereby maintaining continuity of continuous material portions along the length of the shell,
Expandable shell. 26. The method of claim 25,
The slots may have a width in the range of 1/4 inch (6.35 mm) to 3/8 inch (9.53 mm)
Expandable shell. 26. The method of claim 25,
The slots are spaced 6 inches (152 mm) apart from each other,
Expandable shell. 10. The method of claim 9,
The shell further includes a plurality of slots extending between the interior of the shell and the exterior of the shell, the slots generally extending across the length of the shell,
A method for constructing support piers on the ground. 30. The method of claim 29,
Wherein the slots are discontinuous about a circumference of the shell, thereby maintaining continuity of continuous material portions along the length of the shell,
A method for constructing support piers on the ground. 30. The method of claim 29,
The slots may have a width in the range of 1/4 inch (6.35 mm) to 3/8 inch (9.53 mm)
A method for constructing support piers on the ground. 30. The method of claim 29,
The slots are spaced 6 inches (152 mm) apart from each other,
A method for constructing support piers on the ground.

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