Classifications

• • 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
  • E02D5/46—Concrete or concrete-like piles cast in position ; Apparatus for making same making in situ by forcing bonding agents into gravel fillings or the soil
• • 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

Definitions

• the present invention refers to a method for obtaining a micropi le to be used in the methodologies concerning foundations at high depth, i .e. non superficial , and in particular it refers to a micropi le for foundations of bui ldings in soi ls with poor mechanical properties.
• the bore may be "free" or provided with a l ining, i .e. the wal ls of the bore may be stabi l ized by introducing permanently into the ground a sheet metal , or by temporary introducing a tubular casing which wi l l be recovered after casting of the concrete.
• a dri l l ing may be performed by means of a continuos screw with a hol low shaft (auger), and casting the concrete through the shaft of the auger.
• wich have a longitudinal and transversal spiral shaped reinforcement, and are made of concrete by the method of centr i fugat i on , this type of pi les being provided with a metal l ic point adequate for penetrating into the ground.
• Another type of driven caissons is that made of ducti le cast iron T.R.M. (Tirder Roehren und Metal Itechniker A.G. , Hal l I . Tirol ).
• Such bearing pi les are pre-fabr i cated pi les by the method of centr ifugat i on , with a unique form and length, or pi les consisting of a corrugated sheet metal closed at the tip into wich concrete is cast.
• the driven caissons have two important disadvantages. On the one side, since they are pre-fabr i cated , they must be trasported to the bui lding yard. Furthermore, their tamping l imits their appl ications in places where vibrations may cause damages.
• micropi les A last type of bearing pi les for high-depth foundations, are the micropi les.
• the micropi les ( ital ian patent n. 497736 issued on the 3rd of november 1952) are real ized by letting penetrate into the soi l a tubular casing wich carries at the tip a perforation crown, the perforation being obtained by special rotation equipments.
• the metal l ic reinforcement is introduced into the tubular casing, for instance a steel rod, or a cage, or a steel tube with a diameter adequate to the the cross sectional area of the tube. Afterwards, the casting of mortar of cement is performed.
• the tubular casing is gradual ly extracted by compressing the casting material .
• a bore is obtained by dri l l ing, and then a tubular steel casing provided with injection valves is inserted.
• the casting is performed in two steps. During the first step, l iquid mortar is poured into the air space formed by the bore wal ls and the casing. Then the cement mixture is introduced under pressure inside the tubular casing, causing the breakage of the valves and the compaction of the soi l surrounding the tubular casing.
• the present invention is concerned with the real ization of a method for obtaining a micropi le for foundations of bui ldings on soi ls having poor mechanical qual ities, which al lows to overcome the drawbacks of the prior art, prev i ous I y c i ted .
• This object is attained according to the conditions and principles defined in the fol lowing description and c I a i ms .
• Fig. 1 shows the tubular casing, a half of it having been already introduced into the soi l;
• Fig. 2 shows the tubular casing completely fixed into the soi l , when the reinforcement is introduced;
• Fig. 3 i l lustrates the injection step of the concrete inside the tubular casing
• Fig. 4 shows the step of extraction of the tubular cas i ng ;
• Fig. 5 shows the finished micropi le.
• a hol low tube 1 of variable diameter (between 150 mm and 300 mm) is introduced into the soi l 2, the latter being loose or composed by a material of fine particle size or having poor mechanical qual ities, also in presence of an aquifer or a confined aquifer.
• This operation is carried out by making the tube to vibrate and fixing it to the ground at the same ti e. The vibrations cause a compaction of the soi l by compression, increasing its density.
• the hol low tube 1 carries at its lower end a hinge-tip 3.
• a reinforcement 6 is introduced (fig. 2) .
• a special seal ing head 4 is appl ied to the tubular casing, which by means of sleeves is connected to a pump 5 for concrete (Fig. 3) .
• the tubular casing is extracted, making it vibrate at the same ime, and transmitting the vibrations to the concrete 7.
• the lower end of the tubular casing where the hinge-tip is located is submitted to the weight of the overlying column of concrete, the hinge opening itself because of the lack of a reaction force from the underlying soi l .
• micropi le wi l l have a diameter with a width wich varies considerably, according to the sol idity of the l ithotypes adjacent to the surface 5 portion of the stem, and the micropi le wi l l also have a particularly rough surface, advantageously increasing the lateral friction of the micropi le, which for example in the case of the bearing pi les with a casing permanently introduced into the ground, was particularly
• the method according to the present invention is appl icable to a type of soi l with poor mechanical qualities, for example: peats, si lts, low density sands, but also for clays, sands and loose gravel , and in the presence of a confined aquifer.
• the method may be appl ied to the real ization of foundations in al luvial deposits and for off-shore platforms.
• the low costs of the method of the invention also al lows to substitute the use of a traditional pi le by more than one micropi le, by maintaining an advantageous load/cost ratio, by el iminating the cost l imit set by the use of traditional micropi les in the field of foundations of bu i I d i ngs .

Landscapes

• 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)
• Sampling And Sample Adjustment (AREA)
• Investigation Of Foundation Soil And Reinforcement Of Foundation Soil By Compacting Or Drainage (AREA)
• Piles And Underground Anchors (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=11400667

Family Applications (1)

Country Status (3)

Cited By (14)

Citations (2)

• 1992
  • 1992-02-07 IT ITRM920085A patent/IT1254303B/it active
• 1993
  • 1993-02-03 WO PCT/IT1993/000008 patent/WO1993016236A1/en active Application Filing
  • 1993-02-03 AU AU34626/93A patent/AU3462693A/en not_active Abandoned

Patent Citations (2)

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