EP0398762A1 - Zementstrukturen - Google Patents

Zementstrukturen Download PDF

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Publication number
EP0398762A1
EP0398762A1 EP90305446A EP90305446A EP0398762A1 EP 0398762 A1 EP0398762 A1 EP 0398762A1 EP 90305446 A EP90305446 A EP 90305446A EP 90305446 A EP90305446 A EP 90305446A EP 0398762 A1 EP0398762 A1 EP 0398762A1
Authority
EP
European Patent Office
Prior art keywords
tube
cementitious
pile
cementitious material
hardened
Prior art date
Legal status (The legal status 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 status listed.)
Granted
Application number
EP90305446A
Other languages
English (en)
French (fr)
Other versions
EP0398762B1 (de
Inventor
Wilfred George Kenneth Fleming
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Cementation Skanska Ltd
Original Assignee
Kvaerner Cementation Foundations Ltd
Cementation Piling and Foundations Ltd
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 Kvaerner Cementation Foundations Ltd, Cementation Piling and Foundations Ltd filed Critical Kvaerner Cementation Foundations Ltd
Publication of EP0398762A1 publication Critical patent/EP0398762A1/de
Application granted granted Critical
Publication of EP0398762B1 publication Critical patent/EP0398762B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
    • E04B1/62—Insulation or other protection; Elements or use of specified material therefor
    • E04B1/66—Sealings
    • E04B1/68—Sealings of joints, e.g. expansion joints
    • E04B1/6816—Porous tubular seals for injecting sealing material
    • 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
    • E02D5/64—Repairing piles

Definitions

  • This invention relates to a method of constructing cementitious structures, in particular (but not exclusively) underground concrete structures, for example piles.
  • underground concrete structures for example piles.
  • the pile When a pile is formed in a pre-formed bore in the ground, the pile has a tendency to crack as a result of mechanical or thermal stresses before the load which the pile is intended to carry is emplaced.
  • the present invention proceeds from an appreciation that the cost of heavy reinforcement in pile construction is unnecessary, provided that proper corrective measures for treating cracks in piles can be achieved. Pressure grouting of such cracks after such site excavation is completed will satisfactorily deal with the temporary cracks, and if the grout pressure is sufficiently high, the shortening of the pile can to a large extent be negated and pile performance can be preserved. The costs of drilling through a concrete pile to the location of a crack in order to permit pressure grouting is however unacceptably high. The present invention therefore aims to provide a technique whereby pressure grouting can be achieved relatively simply and therefore relatively cheaply.
  • a method of protecting and/or stabilising a cementitious structure from adverse effects due to ground heave and/or thermal shrinkage which comprises embedding into the cementitious structure during its construction and before the cementitious material has hardened at least one tube having on its outer surface one or more spirally formed grooves in order to assist bonding between the tube and the cementitious material and additionally to provide a zone or zones of weakness in the tube; and, after the cementitious material has hardened, injecting grout under pressure through said tube, whereby grout has access through any ruptured zones in the tube to fractures in the hardened cementitious material of the structure itself.
  • the or each tube is advantageously formed of a metal, e.g. mild steel.
  • the requirement for the tube is that it should be formed of a material capable of forming a strong bond to concrete, but which can easily be fractured.
  • brittle plastics materials may be used.
  • the ratio between the diameter of the or each metal tube and the pile diameter is in the range of 1:12 to 1:60. It is also advantageous for two or more tubes to be embedded at or close to the periphery of the pile, and in order to provide access for grouting purposes, the or each tube should extend to the top of the pile, thereby giving ready access to its interior.
  • the spirally formed groove or grooves make an angle of not less than 20° with respect to the axis of the tube.
  • the or each groove may be in the form of a helix (i.e. a continuous running groove) or it may be in the form of arcuate sections which may or may not extend to a complete revolution about the tube.
  • the depth of the or each spirally formed groove is advantageously in the range 0.5mm to 10mm.
  • the pitch of the or each groove is advantageously in the range 20mm to 400mm.
  • each 25mm inside diameter and of 4mm wall thickness will be located at the periphery of the pile while the cementitious material is still fluid.
  • Each tube (or pipe) may be grooved with a helical groove (e.g. formed on site by means of lathe), and typically a groove depth of 2mm and a pitch of 100mm mm will be satisfactory. In such a case, the helical groove makes an angle of 33.82° with the longitudinal axis of the metal tube.
  • the groove formed on the outside of the or each tube provides a good bond with the cementitious material of the pile in which it is embedded.
  • the force necessary to disrupt such a metal tube would be about 50kN if the tube is made of mild steel; this force is well below the level of forces which generate cracks in piles. As mentioned earlier, forces of the order of 3500 kN are frequently experienced by 1.5m diameter piles.
  • each tube is capped and left protruding from the pile head until required.
  • Capping of the pipes at their upper (and, if desired, lower) ends may be achieved by using screw caps.
  • the tube caps should be readily accessible in order to permit injection of grout at the end of the site excavation stage.
  • the upper length of the tube close to the pile head needs no grooving, since the tube is not required to disrupt at these levels.
  • a tube used in accordance with method of this invention needs to carry its external grooving only over that region of its length which corresponds to the zone of anticipated cracking. Since the exact location of any crack or cracks cannot be predicted, a continuous helical groove over the pre­determined portion of the length of the tube is necessary.
  • the full tensile force may be instantly transferred to three or four tubes located in the pile, and these forces are such that they will disrupt the tubes at the level of the cracks, thereby providing access for grout which can be forced into the crack under pressure and up any tubes not connected to the grout inlet.
  • a plurality of tubes are embedded in the cementitious structure during its construction and before it has hardened, and pressurised grout is inserted into the tubes in a plurality of stages, one or more of the tubes undergoing grouting at each stage.
  • pressurised grout is inserted into the tubes in a plurality of stages, one or more of the tubes undergoing grouting at each stage.
  • Fig. 1 shows a mild steel tube 1 embedded within, but at the periphery of, cementitious material 2 which, when hardened, will form a pile.
  • the tube 1 has an inside diameter of 25mm and a wall thickness of 4mm.
  • Four such tubes are positioned equidistantly around the circumference of the shaft containing cementitious material 2, which is 1.5m in diameter and 20m deep.
  • a helical groove 3 is formed in the outer surface of tube 1 over the lower 12m of the tube; the uppermost part 4 of the tube 1 projects above the ground level 5 at the top of the shaft containing material 2.
  • Groove 3 is 2mm deep and has a pitch of 65mm.
  • the grooved pipes such as 1 are positioned in the fluid cementitious material 2, which is then allowed to harden.
  • Mechanical and/or thermal stresses during hardening cause cracks such as 6 (Fig. 2) to form across the width of the pile 21.
  • Such cracks are typically 5-20mm wide.
  • the tensile forces acting to create crack 6 also affect tube 1, which by this time has become intimately bonded to the hardened cementitious material. This results in fracture of the tube 1 along a part 7 of the groove 3.
  • grout is supplied under pressure at 8 to the top of tube 1, and travels downwardly to the base of the tube. Fissure 7 in groove 3 permits the grout to enter crack 6, where the grout hardens in due course and, in effect, restores the integrity of pile 21.
  • a length of cold rolled mild steel tubing of 30mm outside diameter (o.d.) was cut into 300mm sections.
  • the tubing size was not significant other that it was readily available from current stocks.
  • a helical groove was machine cut (4 turns/inch) into each of the sections surface, each section having a different remaining wall thickness.
  • the tube sections were mounted in a load frame (modified Contraves ZM5Oa) and stresses in tension at a rate of 2.5mm/min were applied until failure.
  • a box 230 x 230 x 850mm was constructed with the groove tube placed centrally. 16mm diameter studding was used as anchor bolts so that the tensile load could be applied through the block once it had been cast.
  • the box was filled with concrete and compacted using a small diameter poker vibrator. A plastic sheet was introduced midway to act as a crack inducer to the concrete.
  • the block was mounted in the load frame and a 1m head of water applied to the helical grooved tube.
  • the specimen was stressed in tension at a rate of 2.5mm/min. until failure occurred.
  • the opc grout had a w/c ratio of 0.4. and was placed with a head of 1m.
  • a manual cut could only be produced in one pass of the lathe thus restricting the groove depth.
  • the pipe fractured allowing water to escape through the crack.
  • the rate of loading was held at zero to keep the block in position for inspection.
  • On inspection the crack width was approximately 2mm. It was evident that the helix had opened up as the specimen could be 'stretched' and 'relaxed' thus opening and closing the crack.

Landscapes

  • Engineering & Computer Science (AREA)
  • Structural Engineering (AREA)
  • Civil Engineering (AREA)
  • Architecture (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Mining & Mineral Resources (AREA)
  • Paleontology (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Piles And Underground Anchors (AREA)
EP19900305446 1989-05-18 1990-05-18 Zementstrukturen Expired - Lifetime EP0398762B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8911403 1989-05-18
GB898911403A GB8911403D0 (en) 1989-05-18 1989-05-18 Improvements relating to underground concrete structures

Publications (2)

Publication Number Publication Date
EP0398762A1 true EP0398762A1 (de) 1990-11-22
EP0398762B1 EP0398762B1 (de) 1993-05-05

Family

ID=10656945

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19900305446 Expired - Lifetime EP0398762B1 (de) 1989-05-18 1990-05-18 Zementstrukturen

Country Status (3)

Country Link
EP (1) EP0398762B1 (de)
DE (1) DE69001506D1 (de)
GB (1) GB8911403D0 (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104947723A (zh) * 2014-03-28 2015-09-30 中国二十冶集团有限公司 嵌岩灌注桩桩底预裂注浆方法
CN112523202A (zh) * 2020-11-23 2021-03-19 中冶交通建设集团有限公司 钻孔灌注桩断桩处理施工方法
CN113897951A (zh) * 2021-10-26 2022-01-07 邓亚光 超载验证劲性复合桩的施工方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2192422A (en) * 1986-07-11 1988-01-13 Kaken Leon Kk Device for grouting buildings
DE3642919A1 (de) * 1986-12-16 1988-06-23 Wolfgang Rieck Verfahren und mittel zum ausfuellen von unerwuenschten hohlraeumen und risse bei der herstellung von verbundestrich, stuetzen, unterzuegen, fertigteilen etc. aus beton

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2192422A (en) * 1986-07-11 1988-01-13 Kaken Leon Kk Device for grouting buildings
DE3642919A1 (de) * 1986-12-16 1988-06-23 Wolfgang Rieck Verfahren und mittel zum ausfuellen von unerwuenschten hohlraeumen und risse bei der herstellung von verbundestrich, stuetzen, unterzuegen, fertigteilen etc. aus beton

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104947723A (zh) * 2014-03-28 2015-09-30 中国二十冶集团有限公司 嵌岩灌注桩桩底预裂注浆方法
CN104947723B (zh) * 2014-03-28 2016-08-17 中国二十冶集团有限公司 嵌岩灌注桩桩底预裂注浆方法
CN112523202A (zh) * 2020-11-23 2021-03-19 中冶交通建设集团有限公司 钻孔灌注桩断桩处理施工方法
CN113897951A (zh) * 2021-10-26 2022-01-07 邓亚光 超载验证劲性复合桩的施工方法

Also Published As

Publication number Publication date
EP0398762B1 (de) 1993-05-05
GB8911403D0 (en) 1989-07-05
DE69001506D1 (de) 1993-06-09

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