WO2021032596A1 - Procédé de formation d'une fondation dans le sol - Google Patents

Procédé de formation d'une fondation dans le sol Download PDF

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Publication number
WO2021032596A1
WO2021032596A1 PCT/EP2020/072785 EP2020072785W WO2021032596A1 WO 2021032596 A1 WO2021032596 A1 WO 2021032596A1 EP 2020072785 W EP2020072785 W EP 2020072785W WO 2021032596 A1 WO2021032596 A1 WO 2021032596A1
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WO
WIPO (PCT)
Prior art keywords
foot
forming
pile
vibrator arrangement
vibrator
Prior art date
Application number
PCT/EP2020/072785
Other languages
English (en)
Inventor
Alexander Degen
Wilhelm Degen
Original Assignee
Alexander Degen
Wilhelm Degen
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Alexander Degen, Wilhelm Degen filed Critical Alexander Degen
Priority to US17/637,092 priority Critical patent/US20220290395A1/en
Publication of WO2021032596A1 publication Critical patent/WO2021032596A1/fr

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D27/00—Foundations as substructures
    • E02D27/10—Deep foundations
    • E02D27/12—Pile foundations
    • E02D27/16—Foundations formed of separate piles
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
    • E02D5/22—Piles
    • E02D5/34—Concrete or concrete-like piles cast in position ; Apparatus for making same
    • E02D5/38—Concrete or concrete-like piles cast in position ; Apparatus for making same making by use of mould-pipes or other moulds
    • E02D5/44—Concrete or concrete-like piles cast in position ; Apparatus for making same making by use of mould-pipes or other moulds with enlarged footing or enlargements at the bottom of the pile
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D3/00—Improving or preserving soil or rock, e.g. preserving permafrost soil
    • E02D3/02—Improving by compacting
    • E02D3/046—Improving by compacting by tamping or vibrating, e.g. with auxiliary watering of the soil
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D3/00—Improving or preserving soil or rock, e.g. preserving permafrost soil
    • E02D3/02—Improving by compacting
    • E02D3/046—Improving by compacting by tamping or vibrating, e.g. with auxiliary watering of the soil
    • E02D3/054—Improving by compacting by tamping or vibrating, e.g. with auxiliary watering of the soil involving penetration of the soil, e.g. vibroflotation
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D3/00—Improving or preserving soil or rock, e.g. preserving permafrost soil
    • E02D3/02—Improving by compacting
    • E02D3/08—Improving by compacting by inserting stones or lost bodies, e.g. compaction piles
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
    • E02D5/22—Piles
    • E02D5/24—Prefabricated piles
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
    • E02D5/22—Piles
    • E02D5/34—Concrete or concrete-like piles cast in position ; Apparatus for making same
    • E02D5/36—Concrete or concrete-like piles cast in position ; Apparatus for making same making without use of mouldpipes or other moulds
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
    • E02D5/22—Piles
    • E02D5/34—Concrete or concrete-like piles cast in position ; Apparatus for making same
    • E02D5/38—Concrete or concrete-like piles cast in position ; Apparatus for making same making by use of mould-pipes or other moulds
    • E02D5/385—Concrete or concrete-like piles cast in position ; Apparatus for making same making by use of mould-pipes or other moulds with removal of the outer mould-pipes
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D7/00—Methods or apparatus for placing sheet pile bulkheads, piles, mouldpipes, or other moulds
    • E02D7/02—Placing by driving
    • E02D7/06—Power-driven drivers
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D7/00—Methods or apparatus for placing sheet pile bulkheads, piles, mouldpipes, or other moulds
    • E02D7/18—Placing by vibrating
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D2250/00—Production methods
    • E02D2250/0007—Production methods using a mold
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D2250/00—Production methods
    • E02D2250/0023—Cast, i.e. in situ or in a mold or other formwork
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D2300/00—Materials
    • E02D2300/0004—Synthetics
    • E02D2300/0018—Cement used as binder
    • E02D2300/002—Concrete
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D2300/00—Materials
    • E02D2300/0026—Metals
    • E02D2300/0029—Steel; Iron
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D2300/00—Materials
    • E02D2300/0071—Wood

Definitions

  • This disclosure in general relates to a method for forming a foundation capable of bearing a load in the ground.
  • Rigid bodies such as concrete piles may be used as foundations in the ground for any kind of structure when a load bearing capability of the ground is not high enough to support the structure on a shallow foundation.
  • One example relates to a method.
  • the method includes forming a mate rial foot in the ground, forming a material column on top of the material foot, and form ing a pile inside the material column such that the pile extends down to the foot or into the foot.
  • Figures 1 A to 1C illustrate one example of a method for forming a foun dation in the ground, wherein the foundation includes a pile and a bedding of the pile, wherein the bedding includes a material foot and a material column;
  • Figure 2 illustrates one example of a depth vibrator in greater detail
  • Figures 3A to 3C illustrate method steps for producing the material foot according to one example
  • Figures 4A and 4B illustrate one example of a method for forming the pile of the foundation in the bedding
  • Figures 5 A and 5B illustrate another example of a method for forming the pile
  • Figures 6A and 6B illustrate yet another example of a method for form ing the pile
  • Figure 7 illustrates one example of a concrete pile manufactured in a con ventional way using a so-called continuous flight auger method
  • Figure 8 illustrates another example of a foundation, wherein this founda tion has been formed without a material column.
  • One way of forming a foundation capable of bearing a load includes ram ming a precast rigid element, such as a concrete pile into the ground.
  • a foundation based on piles often requires that the piles are long enough to reach a stable ground region, such as a stiff or dense soil layer or a rock region, capable of bearing large parts of the load provided by the structure through the bottom of the pile.
  • a stable ground region such as a stiff or dense soil layer or a rock region
  • Another way of forming a pile in the ground includes drilling a hole and filling the hole with concrete. This method, similar to driving a precast concrete pile into the ground, requires that the hole is drilled down to a stable ground region capable of bearing the load provided by a structure.
  • Concrete piles with an enlarged foot may be used to form foundations even in a loose ground, such as loose sand or silt, when solid ground regions are too deep to be reached cost efficiently by ramming pre cast piles into the ground or by drilling holes.
  • These Franki piles are formed by ram ming a tube filled at the bottom with gravel or dry concrete into the ground and by driv ing, with a falling weight, the concrete or gravel from the tube into the ground after the tube has reached a desired depth.
  • a foot having a diameter larger than the diameter of the tube is formed. After installation of such foot, and while withdrawing the tube from the ground, the pile is completed by fill ing the hole formed by the tube with concrete down to the foot. This method, however, is slow and, therefore, expensive.
  • the method includes forming a foot 11 in the ground 100. More specifically, forming the foot 11 includes forming the foot 11 spaced apart from a ground surface 101.
  • the foot 11 may be formed in various ways.
  • forming the foot 11 includes introducing material into the ground and forming the foot 11 using a vibrator arrangement 2.
  • the foot 11, which may also be referred to as material foot is formed such that a diameter dl of the material foot 11 is larger than a diameter d2 of the vibrator arrangement 2.
  • a method for forming the material foot 11 using the vibrator arrangement 2 is explained in greater detail herein further below.
  • the material foot 11 is formed from concrete.
  • the material foot 11 is formed from a granular material, such gravel or sand.
  • the material foot 11 includes a granu lar material and grout.
  • grout may be injected from grouting nozzles (not shown) attached to the vibrator arrangement 2 at the same time as the granular material is introduced into the ground, wherein the grout provides for a bonding between the stones or grains of the granular material of the material foot 11.
  • the method further includes forming a material column 12 on top of the material foot 11.
  • the material column 12 may extend from the material foot 11 to the ground surface 101.
  • the material col umn may be formed from one or more different materials. These materials include, for example, gravel or sand.
  • the gravel may include angular gravel or rounded river gravel.
  • the material column is formed from only one material, such as gravel or sand.
  • the material column is formed from two or more different materials, such as gravel and sand.
  • the column may be formed such that it includes two or more column sections, wherein each column section only includes one material, such as gravel or sand.
  • the type of material and, optionally, the size of the material particles may be selected dependent on the type of soil in which the respective column section is formed.
  • the ground may include different soil layers one above the other, wherein for each column section formed in a respective soil layer the column material can be se lected independently.
  • the material column or at least one section of the material column is formed from a mixture of two or more different mate rial, such as sand and gravel.
  • a foundation of the type illustrated in Figure 1C that includes a foot 11, a material column 12 on top of the material foot 11, and a rigid pile 13 inside the material column 12 provides an increased lateral support of adjustable magnitude over depth, as compared to a conventional foundation formed in the ground.
  • This higher lateral sup port can be beneficial to increase the portion of the load to the pile 13 that is carried by a shaft of the pile 13 as compared to a bottom of the pile 13, wherein the bottom of the pile 13 is the section of the pile 13 that faces the foot 11.
  • Higher lateral support can also be beneficial to reduce the moment load in the pile shaft when the pile is horizontally loaded or loaded by a moment on the pile head, wherein the pile head is a section of the pile facing away from the foot 11.
  • the vibrator arrangement 2 that may be used for forming the material foot 11 is only schematically illustrated in Figure 1 A. Vibrator arrangements for intro ducing material into the ground are known. Nevertheless, for a better understanding, one example of a vibrator arrangement 2 is briefly explained with reference to Figure 2 in the following.
  • the vibrator arrangement 2 includes a silo tube 21, a vibrator 23, which may also be referred to as vibroflot, coupled to the silo tube 21 and including a tip 25.
  • the tip 25 forms a lower end of the vibrator arrangement 2.
  • the vibrator 23 may be coupled to the silo tube 21 by a damper element 22.
  • the vi brator arrangement 2 includes a pipe 24 connected to the silo tube 21 and extending from the silo tube 21 towards the lower end of the vibrator arrangement 2, wherein the pipe 24 has an outlet 26 at the lower end of the vibrator arrangement 2.
  • the vibrator arrangement 2 includes an inlet 27 (illus trated in Figure 1 A), wherein material can be fed into the silo tube 21 via the inlet 27. Material fed into the silo tube 21 can be introduced into the ground 100 via the outlet 26 of the pipe 24 connected to the silo tube 21.
  • the silo tube 21 may include one or more locks in order to apply excess air pressure in the silo tube 21 to control material flow from the input 27 to the outlet 26 against the in-situ pressure in the soil. Such locks, however, are not illustrated in the drawings. [0026]
  • the tip 25 of the vibrator oscillates (repeatedly moves) in lateral directions, which are directions parallel to the ground surface 101 and perpendic ular to a longitudinal direction of pipe. In this way, the vibrator 23 laterally compacts the ground and creates space for the vibrator arrangement 2 to move into the ground, just driven by its own weight.
  • the vibrator arrangement 2 illustrated in Figure 2 includes one pipe 24 and one outlet 26. This, however, is only an example. According to another example (not illustrated) two or more pipes extend from the silo tube 21 along the vibrator 23 to the lower end of the vibrator arrangement 2.
  • FIGs 3A to 3C illustrate, in greater detail, one example of a method for forming the foot 11 in the ground 100 using a vibrator arrangement.
  • this method includes introducing the vibrator arrangement 2 to a predefined depth into the ground 100.
  • the vibrator arrangement 2 may be held by a suitable device, such as an excavator arm, and may be lowered or lifted by this device.
  • a suitable device such as an excavator arm
  • For introducing the vi brator arrangement 2 into the ground 100 no external force is required.
  • the vibrator arrangement 2 penetrates into the ground 100 just supported by its own weight and vibrations of the vibrator 23, wherein these vibrations of vibrator 23 create a space at the lower end of the vibrator arrangement 2 that enables the vibrator arrangement 2 to penetrate deeper into the ground 100.
  • the device holding the vibrator arrangement 2 may stop lowering the vibrator arrangement 2 so that the vibrator arrangement 2 stops penetrating deeper into the ground 100.
  • the method further includes lifting the vibrator arrangement 2 and introducing material 11 ’ into a space below the lower end of the vi brator arrangement 2, wherein this space has been created by the vibrator arrangement 2.
  • the silo tube 21 has been filled with material before, so that automatically when the vibrator arrangement 2 is lifted the material 1 G is intro pokerd into the ground via the silo tube 21 and the pipe 26.
  • the method further includes lowering the vibrator arrangement 2 into the material 1 G.
  • the material 1 G is compacted and driven mainly radially into the ground surrounding the space into which the material 11 ’ had been introduced.
  • Forming the material foot 11 may include repeating the method steps il lustrated in Figures 3A to 3C several times, that is, (a) lifting the vibrator arrangement 2 in order to introduce material 1 G into the ground 11, and (b) penetrating into the intro Jerusalem material 1 G by the vibrator arrangement 2 in order to compact the material 11 ’ and drive the material into ground regions surrounding the material.
  • a size of the mate rial foot 11, that is, a height of the material foot 11 in a direction perpendicular to the ground surface 101, and a width or diameter dl of the material foot 11 in directions par allel to the ground surface 101 are dependent on an amount of material that is intro Jerusalem into the ground 100. The amount of material increases as the number of repeti tions of the method steps illustrated in Figures 3A to 3C increases.
  • the 100 and forming the material foot 11 may be concrete.
  • This concrete is introduced into the ground in liquid form, wherein the concrete cures (hardens) after being introduced into the ground 100.
  • the material 11 ’ introduced into the ground 100 in order to form the material foot 11 is gravel, wherein the gravel is com pacted by a method step of the type illustrated in Figure 3C.
  • liquid grout may be introduced into the gravel by the vibrator arrangement 2 either from time to time in the process of forming the material foot 11 or after the gravel forming the material foot 11 has been introduced. The liquid grout flows between the gravel and finally cures so that a solid material foot 11 is formed.
  • the material foot 11 is formed such that the diam eter dl of the material foot 11 is greater than a diameter d2 of the vibrator arrangement 2.
  • the diameter d2 of the vibrator arrangement 2 essentially equals the diameter of a hole the vibrator arrangement 2 forms when penetrating into the ground 100. Due to ir regularities in the ground and variations in the manufacturing process of the material foot 11 the material foot 11 might not have the same diameter along its entire height. According to one example, as used herein "the diameter dl of the material foot 11" is an average diameter of the material foot 11.
  • the diameter dl of the material foot 11 is at least two times the diameter d2 of the vibrator arrangement 2, dl>2*d2. According to one example, the diameter dl of the material foot 11 is between two times and five times the diameter d2 of the vibrator arrangement 2, 2*d2 ⁇ dl 5*dl. According to one example, the diameter dl of the material foot 11 is between 0.5 meters (m) and 2 me ters.
  • the diameter dl of the material foot 11 is con trolled by controlling or monitoring at least one operating parameter of the vibrator ar rangement.
  • the at least one operating parameter is a power consumption of the vibrator 23 when the vibrator arrangement 2 (by its weight and vi brations of the vibrator 23) is driven into the material of the material foot 11.
  • the power consumption may be measured by measuring an electric power consumption of a motor of the vibra tor arrangement 2 or by measuring a hydraulic pressure in a motor of the vibrator ar rangement 2.
  • the power consumption of the vibrator 23 required to penetrate into the introduced material is a function of the stiffness / density of the material and also the soil that surrounds the material into which the vibrator arrangement 2 penetrates.
  • the stiffer or denser the material the higher is the power consumption and the higher is also the lateral confinement between the installed column 12 and the sur rounding soil.
  • the power consumption is measured and the method steps of lifting and lowering the vibrator arrangement 2 is repeated until the power consumption reaches a predefined threshold. Basically, the weaker the ground, the greater the diameter of the material column 12 will be before a desired power consumption threshold is reached.
  • an acceleration or a velocity of the vibrator arrangement 2 may be monitored. This may be achieved by placing one or more accelerometers or velocity sensors at the vibrator arrangement 2. The measured acceleration or velocity, similar to a power measurement, can be correlated with the confinement generated by the vibrator arrangement 2 while building the foot 11.
  • forming the material foot 11 using a vibrator arrangement includes introducing a predefined amount of material into the ground 100 and compacting the material using the vibrator arrangement 2.
  • the material foot is formed in accordance with forming the material foot in the Franki pile method explained above.
  • forming the material foot includes: ramming a tube filled at the bottom with gravel or dry concrete into the ground; and driving, with a falling weight, the concrete or gravel from the tube into the ground.
  • a foot having a diameter larger than the diameter of the tube is formed.
  • the foot 11 has a diameter larger than a diame ter of the tube.
  • the diameter of the material foot 11 may be between two times and five times the diameter of the tube.
  • the diameter dl of the mate rial foot 11 is between 0.5 meters (m) and 2 meters.
  • forming the material foot 11 includes: ramming a tube having a lock at its lower end into the ground until the tube reaches a desired depth; partially filling the tube with gravel or dry concrete; withdrawing the tube and opening the lock so that the filling material is introduced into a hole below the tube; closing the lock and driving the tube into the material at least once.
  • the tube may be lifted and driven into the material several times.
  • the lock may be implemented in such a way that it automatically opens when the tube is lifted and closes when the tube is driven into the material.
  • the foot 11 has a diameter larger than a diameter of the tube.
  • the diameter of the material foot 11 may be between two times and five times the diam eter of the tube.
  • the diameter dl of the material foot 11 is between 0.5 meters (m) and 2 meters.
  • forming the foot 11 using one of the methods explained above are just examples. Other examples include: forming the foot using any type of top driven mandrel with or without a lock; forming the foot 11 using a rotary bottom feed stone column technique; forming the foot 11 using a top feed technique, wet or maybe even dry; or the like.
  • the vibrator arrangement 2 may penetrate into the ground 100 just supported by its own weight and vibrations of the vibrator 23. Further, referring to Figures 3A-3C, the ground may include different soil layers 110-140, wherein one or more of these soil layers may be too stable for the vibrator arrangement 2 to penetrate through.
  • the hole at the bottom of which the material foot 11 is formed by the vibrator arrangement 2 is at least partially predrilled. That is, a hole is formed by a drilling device such that the hole extends through soil layers impenetrable by the vibrator arrangement 2. After removing the drilling device, the vibrator arrange ment is lowered into the predrilled hole in order to form the material foot 11 as ex plained above.
  • a depth of the predrilled hole may correspond to the desired depth of the hole at the bottom of which the material foot is to be produced.
  • the predrilled hole is less deep as desired and the vibrator arrangement 2 is used to extend the hole to the desired depth.
  • a diameter of the predrilled hole may be less than the di ameter of the vibrator arrangement 2.
  • the drilling device is an auger, for example.
  • At least partially pre-drilling the hole is not restricted to a method in which the material foot 11 is produced using a vibrator arrangement.
  • the hole may also be pre-drilled when forming the material foot 11 in accordance with any one of the other methods explained above.
  • foot 11 is a material foot that is formed by introducing material into the ground. This, however, is only an example.
  • forming the foot 11 includes compacting ground material. A foot 11 formed in this way may be referred to as in-situ foot. Forming an in-situ foot may in clude using a vibrator arrangement 2 of the type explained above, introducing the vibra tor arrangement 2 to a predefined depth, and repeatedly lifting and lowering the vibrator arrangement.
  • the foot 11 may be formed in this way in a sandy soil layer, for example, wherein each time the vibrator arrangement 2 is lifted ground material flows into the space below the vibrator tip 25 and is compacted when the vibrator arrangement is low ered.
  • the vibrator arrangement 2 may be implemented without a tube in this example.
  • the material column 12 is formed in the hole above the foot
  • Forming the material column 12 may include simply filling the hole with material.
  • Filling the hole with material may be achieved by feeding the column material via the tube 26 of the vibrator arrangement 2 or via any other kind of tube into the hole when the vibrator arrangement 2 or the tube is withdrawn from the hole.
  • the vibrator arrangement 2 or tube is withdrawn from the hole and gravel is filled into the hole after the vibrator arrangement 2 has been withdrawn.
  • the latter may be applied when the ground is stable enough that the hole formed by the vibrator ar rangement 2 remains open after the vibrator arrangement 2 or the tube has been with drawn from the ground.
  • the material column 12 is formed using a wet top feed method. This method uses a deep vibrator that does not have a material pipe attached to it. Instead, the material forming the material column 12 is fed in an an nular space around the vibrator, wherein the space is kept open by flushing water from the vibrator tip. [0048] Referring to the above, the material column may include two or more column sections formed from different materials or material combinations. A material column of this type may be achieved by introducing different materials or different ma terial combinations into the hole at different times of the filling process.
  • forming the material column 12 includes forming the material column 12 using a vibrator arrangement and using the same kind of method steps explained with reference to Figures 3A to 3C, that is, lifting the vibrator arrangement 2 and introducing material into a space below the lower end of the vibrator arrangement 2 and causing the vibrator arrangement 2 to penetrate into the introduced material in order to compact the material and laterally drive the material into the ground.
  • the vibrator arrangement may be the same vibrator arrangement used to form the material foot 11 or a different vibrator arrangement.
  • Forming the material column may include forming several column segments (column sections) one above the other. According to one example, a diameter of the material column 12 is lower than the diam eter dl of the material foot 11.
  • the diameter dl of the material column 12 is larger than the diameter d2 of the vibrator arrangement 2 (dl>d2).
  • the diameter of the material column is between the diameter d2 of the vibrator arrange ment 2 and 1.5 times the diameter d2 of the vibrator arrangement 2 (d2 ⁇ dl ⁇ 1.5*d2).
  • the number of repetitions when forming the gravel col umn is controlled dependent on at least one operating parameter, such a power con sumption, an acceleration, a velocity, etc of the vibrator 23.
  • the power consumption may be measured by measuring an electric power consumption of a motor of the vibra tor arrangement 2 or by measuring a hydraulic pressure in a motor of the vibrator ar rangement 2, depending on the type of motor drive used.
  • the acceleration and the ve locity may be measured using suitable sensors.
  • the stiffness / den sity of the material and also the soil that surrounds the material into which the vibrator arrangement 2 penetrates is a function of the stiffness / den sity of the material and also the soil that surrounds the material into which the vibrator arrangement 2 penetrates.
  • the stiffer or denser the material the higher is the power consumption, the lower is the acceleration and the velocity, and the higher is also the lateral confinement between the installed column 12 and the surrounding soil.
  • at least one operating parameter is measured and the method steps of lifting and lowering the vibrator arrangement 2 is repeated until the operating parameter in each in stallation depth interval reaches a respective predefined threshold.
  • the vibrator arrange ment 2 is then lifted to a greater extent and forming a new segment of the gravel column 12 starts, wherein forming each segment includes lowering the vibrator arrangement 2 into the introduced material at least once.
  • the diameter of the material column 12 may vary along its length. Basically, the weaker the ground, the greater the diameter of the material column 12 will be before a desired operating parameter threshold is reached.
  • a load transfer between the concrete pile 13 and the soil surrounding the material column 12 happens at least in part by shaft friction between the material col umn 12 and soil. Based on this, it may generally be beneficial to increase such shaft friction also in weak layers by raising the lateral stress in such layers by means of the power consumption-controlled installation of the gravel column 12.
  • the column 12 can be produced in such a way that the lateral confinement stress caused by the column 12 is essentially the same at each longitudinal position of the material column 12. This, however, is only an example. In general, monitoring at least one operating parameter makes it possible to control the lateral confinement stress, wherein it may be desirable to vary the lateral confinement stress according to soil mechanical requirements of the particular pile 13 that is embedded in such column 12.
  • the ground may be analyzed beforehand. Analyzing the ground may include any kind of an alytical processes that provides information on stability, thickness, etc. of individual ground layers.
  • One method of analyzing the ground 100 includes measuring a power consumption of a vibrator arrangement when it penetrates into the ground in the process of forming the material foot 11 and/or the material column 12.
  • the pile 13 inside the gravel column 12 may include various kinds of materials and may be formed in various ways.
  • the method includes forming the pile 13 as a concrete pile using a vibrator arrangement 30.
  • This vibrator arrangement 30 may have a lower diameter than the vibrator arrangement 2 used to form the material foot 11. This however, is only an example.
  • the diameter of the vibrator arrangement may also be larger than the diameter of the material column 12.
  • forming the concrete pile 13 in cludes forming a hole in the gravel column 12 by the vibrator arrangement 30 such that the hole in the gravel column 12 extends down to the material foot 11 or into the mate rial foot 11.
  • the hole extends into the material foot 11 such that a depth of the hole in the material foot 11 is between 0.3 times and 0.5 times the height of the material foot 11.
  • forming the pile 13 includes withdrawing the vi brator arrangement 30 from the ground 100 and introducing liquid concrete into the hole formed by the vibrator arrangement 30. Forming the pile 13 in this way may be referred to as cast in place piling.
  • the concrete may be introduced into the hole via the vibrator arrangement while withdrawing the vibrator arrangement 30 from the hole.
  • the pile 13 may include a reinforcement cage.
  • the hole is filled with con crete, either via the vibrator arrangement 30 or after withdrawing the vibrator arrange ment 30 from the hole, and the reinforcement cage is inserted after filling the hole with concrete. Inserting the reinforcement cage may include using a vibrator or any other kind of device capable of driving the reinforcement cage into the liquid concrete.
  • Forming the pile 13 by cast in place piling may result in a high friction between the concrete pile 13 after curing and the material column 12, wherein the fric tion is particularly high when the material column is at least partially formed from an gular gravel.
  • forming the pile 13 includes forming the concrete pile 13 from gravel and grout, wherein both grout and gravel are introduced into the hole via the vibrator arrangement 30.
  • Gravel and grout may be introduced into the hole at the same time.
  • gravel and grout are altematingly introduced into the hole while withdrawing the vibrator arrangement 30 from the hole, wherein the grout flows into the gravel and fills spaces between gravel stones so that, finally and af ter curing, the concrete pile 13 is formed.
  • the grout also flows into spaces of the mate rial column surrounding the hole, so that a high friction between the concrete pile 13 and the material column can be achieved.
  • an auger is used to drill a hole into the material column 12 and the pile 13 is formed as a concrete pile in the drilled hole.
  • Forming the concrete pile may withdraw the auger from the ground and may include the same method steps explained above with regard to forming the concrete pile after entirely withdrawing the vibrator arrangement 2 from the ground 100.
  • the hole is filled with concrete when withdrawing the auger from the ground 100, wherein a reinforcement cage 14 may be inserted after withdrawing the auger from the ground 100.
  • the pile 13 may be formed such that it essentially has the same diameter along its length. This, however, is only an example. According to another example, the pile 13 has a varying diameter. According to one example, the pile diameter increases towards the ground surface 101.
  • forming the pile 13 includes driving a pile 13 into the material column 12.
  • Driving the pile 13 into the material column 12 may include using a conventional ramming or hammering device 5, which is only schematically illustrated in Figures 5A and 5B, or may include any other kind of device that is suitable to drive a precast pile into the ground, such as a top vibrator.
  • the pile 13 may be comprised of any kind of rigid materi als, such as concrete, steel, timber, or combinations thereof.
  • the pile 13 is a precast concrete pile that includes a steel reinforcement cage.
  • the foundation of the type explained above with a material foot 11 spaced apart from the ground surface 101, a material column 12 on top of the material foot, and a pile 13 in the material column may form a part of a solid foundation for any kind of structure.
  • the arrangement is capable of bearing high loads even when the material foot 11 is formed in an initially relatively weak ground, such as compactable sand.
  • vibrator 23 horizontal vibrating depth vibrator
  • the load bearing capability of the rigid body is, inter alia, dependent on a friction between the material column and the surrounding soil and a load bearing capa bility of the material foot 11.
  • the load bearing capability of the material foot 11 is de pendent on the diameter of the material foot 11 and the load bearing capability of the soil region in which the material foot 11 rests.
  • the material column 12 may be formed from a material providing a low friction, such as sand or round (river) gravel. Using this type of material may result in an easier manu facturing of the concrete pile 13, either because the vibrator arrangement 30 can pene trate into the material column 12 more easily, or because a precast concrete pile can be rammed into the material column 12 more easily.
  • Figures 6A and 6B illustrate another example of a method for forming the concrete pile 13 in the material column.
  • the method includes driving a hollow tube 71 that is closed at a bottom end by a shoe 72 into the material column 12. Driving the tube 71 into the material column may include using a vibrator (not shown). Further, referring to Figure 6B, the method further includes filling the tube 71 with liquid concrete or with gravel and grout, and removing the tube from the ground, thereby forming the concrete pile 13. The shoe 72 remains in the material col umn 12 of the foot 11 after removing the tube (lost shoe).
  • a reinforcement cage is installed in the tube 71 before filling the tube 71 or after filling and withdrawing the tube 71.
  • the pile may be formed in such a way that it extends to the ground surface 101.
  • the pile 13 is formed in such a way that its upper end is spaced apart from the ground surface, wherein a distance between the upper end and the ground surface 101 is between 0.5 and 1.5 meters, for example.
  • a so called load transfer platform may be formed between the upper end of the pile 13 and the ground surface.
  • the load transfer platform may include compacted crushed gravel with layers of rein forcement (geogrids and the like).
  • the material column 12 which is proucked prior to forming the concrete pile 13 (and which may be installed with variable diameter, i.e. a stronger diameter in a weak soil layer 130 as compared to a smaller di ameter in stiff er/denser soil layers 140) stabilizes the ground before forming the con crete pile 13.
  • This stabilizing of the ground 100 is more intense in weak layers than in stronger soil layers.
  • Forming the material layer 12 pre-stresses the surrounding soil lat erally, wherein by such pre-stressing it can be prevented that liquid concrete of the con crete pile expands in such weak layers under its self-weight, which would lead to the well-known bottlenecking effect as shown in Figure 7 (see 61).
  • bottle necks in the concrete pile can be avoided. This is explained with reference to Figure 7 in greater detail.
  • Figure 7 schematically illustrates a concrete pile 6 that has been formed by drilling a hole in the ground and filling the hole with concrete.
  • the hole needs to be drilled down to a solid region, such as bedrock 110, so that the hole must not end in a relatively loose region such as compactable sand region 120.
  • the weight of the concrete before curing provides a load to the ground sur rounding the hole. This may result in an unwanted varying diameter of the concrete pile, wherein the weaker the surrounding material, the larger the diameter.
  • a bottle neck may be formed such that the concrete pile 61 locally has a diameter that is smaller than the diameter of the hole formed before.
  • the pile would be interrupted at such a transition zone between strong soil 140 and weak soil 130 and no longer be contiguous over its full length.
  • forming a foundation without the material column may include forming the foot 11 in accordance with one of the methods explained above and forming the pile 13 in the hole that remains above the foot 11 after installing the foot 11.
  • Forming the pile 13 may include any one of the pile forming methods explained above.
  • a foundation formed in this way is illustrated in Figure 8.
  • the pile 13 is a precast pile in accordance with any of the examples explained above and has a diameter that is larger than a diam eter of the hole remaining above the foot 11.
  • the pile 13 is driven into the ground using any kind of driving device, wherein the hole provides a guidance for the precast pile 13.

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  • Engineering & Computer Science (AREA)
  • Structural Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Mining & Mineral Resources (AREA)
  • Paleontology (AREA)
  • Civil Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Agronomy & Crop Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Soil Sciences (AREA)
  • Investigation Of Foundation Soil And Reinforcement Of Foundation Soil By Compacting Or Drainage (AREA)

Abstract

L'invention concerne un procédé de formation d'une fondation dans le sol, comprenant les étapes consistant à : - former un pied (11) dans le sol (100);- former une colonne (12) à partir d'un matériau de support de charge dans le sol (100) au-dessus du pied (11); et -former une pile (13) dans la colonne de matériau (12) de telle sorte que la pile (13) s'étend vers le bas jusqu'au pied de matériau (11) ou dans le pied de matériau (11).
PCT/EP2020/072785 2019-08-22 2020-08-13 Procédé de formation d'une fondation dans le sol WO2021032596A1 (fr)

Priority Applications (1)

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US17/637,092 US20220290395A1 (en) 2019-08-22 2020-08-13 Method for forming a foundation in the ground

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US201962890496P 2019-08-22 2019-08-22
US62/890,496 2019-08-22

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3416679A1 (de) * 1984-05-05 1985-11-14 Gkn Keller Gmbh, 6050 Offenbach Verfahren und vorrichtung zum herstellen von gruendungen durch einbinden von fertigteilen, insbesondere von stuetzen, im ortfuss
WO2003091503A1 (fr) * 2002-04-24 2003-11-06 Vibroflotation B.V. Procede et dispositif pour produire des colonnes de materiaux dans le sol
KR100762991B1 (ko) * 2006-08-08 2007-10-02 지에스이앤씨(주) 고강도 몰탈을 충진하는 기성말뚝 매입공법

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4397588A (en) * 1981-01-23 1983-08-09 Vibroflotation Foundation Company Method of constructing a compacted granular or stone column in soil masses and apparatus therefor
AU2017418336B2 (en) * 2017-06-12 2024-06-13 Ppi Engineering & Construction Services, Llc Combination pier
US10640944B2 (en) * 2017-07-28 2020-05-05 Ppi Engineering & Construction Services, Llc Pier tool and method of use

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3416679A1 (de) * 1984-05-05 1985-11-14 Gkn Keller Gmbh, 6050 Offenbach Verfahren und vorrichtung zum herstellen von gruendungen durch einbinden von fertigteilen, insbesondere von stuetzen, im ortfuss
WO2003091503A1 (fr) * 2002-04-24 2003-11-06 Vibroflotation B.V. Procede et dispositif pour produire des colonnes de materiaux dans le sol
KR100762991B1 (ko) * 2006-08-08 2007-10-02 지에스이앤씨(주) 고강도 몰탈을 충진하는 기성말뚝 매입공법

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
"DAS TIEFENRUETTELVERFAHREN", KELLER, XX, XX, 1 January 1996 (1996-01-01), pages 1 - 12, XP000646946 *

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