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EP1468146A1 - Construction et conception d'elements de fondation - Google Patents

Construction et conception d'elements de fondation

Info

Publication number
EP1468146A1
EP1468146A1 EP03700872A EP03700872A EP1468146A1 EP 1468146 A1 EP1468146 A1 EP 1468146A1 EP 03700872 A EP03700872 A EP 03700872A EP 03700872 A EP03700872 A EP 03700872A EP 1468146 A1 EP1468146 A1 EP 1468146A1
Authority
EP
European Patent Office
Prior art keywords
volume
foundation element
concrete
ground material
piles
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.)
Withdrawn
Application number
EP03700872A
Other languages
German (de)
English (en)
Inventor
Melvin Gerrard England
Peter Gilbert Shotton
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
Cementation Foundations Skanska 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 Cementation Foundations Skanska Ltd filed Critical Cementation Foundations Skanska Ltd
Publication of EP1468146A1 publication Critical patent/EP1468146A1/fr
Withdrawn legal-status Critical Current

Links

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
    • E02D27/14—Pile framings, i.e. piles assembled to form the substructure
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D2200/00—Geometrical or physical properties
    • E02D2200/16—Shapes
    • E02D2200/165—Shapes polygonal

Definitions

  • the present invention relates to a foundation element and a method of designing and forming the same.
  • the present invention relates to a foundation element which is designed by consideration of a number of parameters including the contribution of ground material to the overall bearing capacity of the element .
  • Foundation elements such as piles made from concrete or grout are used in the construction industry to provide support for buildings or other large structures . They may be formed in a number of ways such as installing a pre-formed element vertically in the ground.
  • cast-in-situ methods are commonly used by the piling industry, which involve driving or boring a piling tool to a certain depth, and then withdrawing the tool from the ground while concurrently or subsequently pouring or pumping concrete or grout to the tip of the tool so as to fill the underground void left by the tool.
  • the dimensions, concrete type and consequently the strength of the piles are selected in accordance with the weight of the above ground structure and it is typical to design the pile shaft dimensions according to the allowable stress which will be exerted on the resultant pile for the chosen concrete type.
  • the friction experienced between a foundation element and the surrounding ground material known as “skin friction”
  • the distance around the perimeter of the resultant element is related to the amount of friction experienced between the element and the concrete.
  • the diameter of a cylindrical pile for example will therefore have a direct consequence on the stress exerted on the concrete.
  • a foundation element such as, for example, a conventional bored pile
  • the soil within the vicinity of the pile becomes disturbed and, as a result, adhesion between the pile and the soil becomes lower than would correspond to an undisturbed region of soil, with soil to soil contact.
  • the soil surrounding the pile will have a lower frictional bearing capacity than undisturbed soil. This effect has meant that the full potential contribution of the soil to the bearing capacity of a foundation structure has not been taken into account.
  • the strength of a series or group of piles is conventionally taken to be a variable fraction of the sum of the individual piles, depending on the pile spacing.
  • the reduction applied might typically reduce potential capacity by 20%.
  • the piling industry therefore considers that the group effect of a plurality of piles is that the group capacity is less than the sum of the individual piles.
  • present testing regimes for determining the bearing capacity of a pile or other foundation element involve the application of test axial forces to the top of a single pile to measure the settlement of that pile. To date, there has been virtually no testing of groups of piles.
  • a consequential working rule adopted by the piling industry is to maintain a minimum separation between adjacent piles.
  • This general rule for installing a series of piles is that the spacing between piles is kept at about 3 times the diameter of the pile and should be determined with regard to the nature of the ground, the behaviour of the piles as a group and the overall cost of the foundation. Since a significant proportion of the load is carried by a pile in the skin friction along the surface of the pile, it is important that the adjacent pile surfaces are not damaged during the installation of other piles. It is uncommon to install piles in closer proximity than the recommended limits. Although piles may occasionally be installed closer together because of space restrictions or when used in retaining wall structures, it is common practice to follow the standard codes set by the piling industry.
  • a method of designing a foundation element wherein the foundation element comprises a volume of concrete and a volume of ground material, the method comprising the steps of: i) determining the total load bearing capacity required by the foundation element; ii) determining the parameters of the foundation element by consideration of the contribution of. the volume of ground material to the overall load bearing capacity of the foundation element.
  • a method of analysing the load bearing capacity of a foundation element comprising the steps of: i) determining the volume and strength of the concrete; and ii) determining the volume and shear strength of ground material which contributes to the overall bearing capacity of the foundation element.
  • the predetermined volume of concrete may advantageously comprise a plurality of discrete concrete sections separated by the predetermined volume of ground material or, alternatively, a monolithic section with a plurality of peripheral concrete sections.
  • the load bearing capacity of a given foundation element can be found and indeed the design of a foundation element can be optimised for given constraints such as concrete strength, space available and structural load.
  • the volume of concrete required to make a single foundation element can be optimised by consideration of the composite contribution of soil to the load bearing capacity and the adhesion perimeter between the element and the surrounding soil.
  • the foundation element may comprise a plurality of individual piles which are installed in the ground in close proximity in a predetermined arrangement .
  • the contribution of the relatively undisturbed soil between adjacent piles means that the group of piles can be considered as acting as a single element such as a large diameter pile.
  • load bearing capacity of the soil and the adhesion between contributing soil and surrounding soil there is a considerable reduction in concrete required to achieve a given load bearing capacity.
  • a composite foundation element comprising a volume of concrete and a volume of ground material, wherein the parameters of the foundation element have been determined by consideration of the contribution of the volume of ground material to the overall load bearing capacity of the foundation element .
  • the spacing between the concrete sections of the composite element may be 2 to 2.5 times the concrete section diameter or less. From a practical point of view, the separation between the concrete sections must be sufficient to ensure that the piles are not damaged during the installation process.
  • a group of piles behaving in composite action will develop high cross-sectional stresses with generally shorter lengths than more conventional piles sizes. As a result of this they are efficient and economical load bearing units. It is therefore envisaged that foundation elements such as this, embodying the present invention, can be used to replace large diameter bored piles.
  • the use of a closely spaced group of "mini piles" has been disregarded by the piling industry due to the recommended spacings between piles and also due to the well known assumption that the bearing capacity of a group of piles has been taken to be a fraction of the sum of the individual piles.
  • Such analysis yields a minimum load for the composite foundation element, which may then be compared to the equivalent non-composite foundation element, such as a large diameter pile and the equivalent number of isolated elemental piles.
  • the settlement of the composite pile is acceptable for the applied structural load. This can be determined by consideration of: the single pile element settlement relative to the composite foundation unit including the elastic shortening; and/or adding the composite unit settlement calculated on the basis of a single pilelike element of equivalent calculated dimensions.
  • each section In order to prevent independent concrete sections from slipping through the element, it is preferable for each section to carry a load which is approximately equal to the load applied to the composite element divided by the number of piles.
  • Figure 1 shows a composite foundation element embodying the present invention having a plurality of discrete concrete sections
  • Figure 2 shows a composite foundation element embodying the present invention, having a ribbed monolithic concrete section
  • Figure 3 shows a composite foundation element embodying the present invention, having a ribbed monolithic concrete section.
  • the composite foundation element as shown in figure 1 comprises a plurality of discrete concrete sections in the form of cylindrical piles 1 and a volume of ground material 2.
  • Each pile has a diameter Dp, wherein the separation between the centres of adjacent piles is defined by S.
  • There exists a predetermined volume of compacted or undisturbed soil 2 disposed between the piles and the composite foundation element is taken to comprise the pile group which defines a rectangular perimeter and the ground material which falls within that perimeter.
  • the pile group is one with M x N piles and the parameters needed for the analysis/design/construction of an optimum foundation element are :
  • N number of piles in the direction at right angles (column)
  • the friction around the group perimeter is calculated on the basis that adhesion on a pile surface is alpha x Cu, but where clay shears against clay it is simply Cu.
  • the clay is assumed to shear on a circular arc between piles of radius R.
  • the spacing S of piles 1 is firstly chosen to be 0.4 metres, or 2 times the pile diameter.
  • the foundation element comprises a rectangular block with straight line sides and that the friction is alpha x Cu all around the group :
  • the spacing S of piles 1 is firstly chosen to be 0.35 metres, or 1.75 times the pile diameter.
  • Pile diameter Dp (metres) .2
  • Pile length in clay L (metres) 15 Cu average along friction length: 150 Cu at base level (kN/sq.m) : 200
  • Adhesion factor - alpha .6
  • the foundation element comprises a rectangular block with straight line sides and that the friction is alpha x Cu all around the group :
  • FIG 2 illustrates a second embodiment of the present invention in which the concrete component of the composite element comprises a cylindrical pile 6, having a plurality of concrete ribs or protrusions 7.
  • the concrete component of the composite element comprises a cylindrical pile 6, having a plurality of concrete ribs or protrusions 7.
  • consideration must also be given to the volume of relatively undisturbed soil 8 which exists within a curved failure plane between adjacent ribs. This soil will not only contribute to the load bearing capacity of the element, but the adhesion and thus the skin friction at 9 between the relatively undisturbed soil and the surrounding soil, is actually greater than the adhesion between the soil/concrete interface.
  • the skin friction at 10 between the edge of the concrete rib and the surrounding soil must also be considered.
  • Figure 3 shows a diaphragm wall 11 having a plurality of concrete ribs 12. Consideration is given to the volume of soil 13 and the friction between the interface 14 between the soil 13 and the surrounding soil, in addition to the skin friction at 15.
  • the length of the protruding ribs outside the nominally cylindrical or rectangular central envelope and. the number of ribs can be optimised for maximum load bearing capacity according to the ground conditions.
  • the precise geometry of the ribs need only ensure that they are of an appropriate size to withstand the maximum shear stresses that may be generated on that protruding section.
  • the orientation of the ribs may be nominally parallel to the axis of the central element or, in the case of the cylindrical form, may be allowed to rotate around the central axis according to depth.
  • the method of formation of these ribs is influenced by the method of installation of the central core of the element.
  • a specific tool can be inserted into the bore, which when at full depth deploys cutters against the bore walls which form the rib shaped protrusions in one operation as the tool is extracted.
  • the tool can be predisposed of a suitable spoil catching bucket.

Landscapes

  • Engineering & Computer Science (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)
  • Structural Engineering (AREA)
  • Piles And Underground Anchors (AREA)
  • Consolidation Of Soil By Introduction Of Solidifying Substances Into Soil (AREA)
  • Foundations (AREA)

Abstract

L'invention concerne un procédé de conception et de fabrication d'un élément de fondation, qui prend en compte un certain nombre de paramètres comprenant la contribution du matériau du sol à la portance globale de l'élément. L'invention concerne également des techniques d'analyse de la force portante d'un élément de fondation composite, qui prennent en compte le volume du matériau du sol existant entre sections de béton distinctes avoisinantes.
EP03700872A 2002-01-23 2003-01-15 Construction et conception d'elements de fondation Withdrawn EP1468146A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
GB0201513 2002-01-23
GB0201513A GB2384510B (en) 2002-01-23 2002-01-23 Construction and design of foundation elements
PCT/GB2003/000135 WO2003062540A1 (fr) 2002-01-23 2003-01-15 Construction et conception d'elements de fondation

Publications (1)

Publication Number Publication Date
EP1468146A1 true EP1468146A1 (fr) 2004-10-20

Family

ID=9929596

Family Applications (1)

Application Number Title Priority Date Filing Date
EP03700872A Withdrawn EP1468146A1 (fr) 2002-01-23 2003-01-15 Construction et conception d'elements de fondation

Country Status (5)

Country Link
US (1) US20050117975A1 (fr)
EP (1) EP1468146A1 (fr)
CA (1) CA2473912A1 (fr)
GB (1) GB2384510B (fr)
WO (1) WO2003062540A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110750901A (zh) * 2019-10-21 2020-02-04 成都理工大学 基于离散元模型的土体扰动范围判断方法

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FI20106346A7 (fi) * 2010-12-20 2012-06-21 Uretek Worldwide Oy Menetelmä ja sovitelma rakenteen tukemiseksi
EP3132094B1 (fr) * 2014-04-14 2018-03-07 Habdank PV-Montagesysteme GmbH & Co. KG Procédé et dispositif de surveillance du battage d'un pieu à battre dans un sol
CN112746610A (zh) * 2019-10-30 2021-05-04 张国梁 混凝土桩
CN112597571B (zh) * 2020-12-17 2022-03-22 贵州正业工程技术投资有限公司 基于传递系数法的复合地基填方边坡稳定性系数计算方法
CN118965522A (zh) * 2024-07-30 2024-11-15 北京城建设计发展集团股份有限公司 一种复合地基中布桩优化设计方法

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DE715314C (de) * 1938-01-09 1941-12-18 Gruen & Bilfinger Ag Gruendung fuer Bauwerke
GB1153188A (en) * 1965-08-11 1969-05-29 Yoshiro Tsuzuki Mould for and method of Moulding concrete piles
US3621663A (en) * 1969-03-13 1971-11-23 Akemasa Otani Ribbed pile
US3797259A (en) * 1971-12-13 1974-03-19 Baker Oil Tools Inc Method for insitu anchoring piling
NL167000C (nl) * 1972-01-13 1981-10-15 Shell Int Research Werkwijze voor het geheel of gedeeltelijk bekleden van vertikale funderingselementen met een bitumineuze glijlaag.
US3913337A (en) * 1972-03-17 1975-10-21 Stanley Merjan Piling
US4614110A (en) * 1984-06-08 1986-09-30 Osterberg Jorj O Device for testing the load-bearing capacity of concrete-filled earthen shafts
JPS6153911A (ja) * 1984-08-23 1986-03-18 Toa Harbor Works Co Ltd 杭の周面摩擦力測定方法
GB2197369B (en) * 1986-08-14 1990-04-25 Shell Int Research Method for installing a hollow pile
US5099696A (en) * 1988-12-29 1992-03-31 Takechi Engineering Co., Ltd. Methods of determining capability and quality of foundation piles and of designing foundation piles, apparatus for measuring ground characteristics, method of making hole for foundation pile such as cast-in-situ pile and apparatus therefor
SU1625958A2 (ru) * 1989-03-03 1991-02-07 Тверской политехнический институт Сва
US5145284A (en) * 1990-02-23 1992-09-08 Exxon Production Research Company Method for increasing the end-bearing capacity of open-ended piles
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US5234290A (en) * 1991-11-04 1993-08-10 Rodney B. Stewart Prestressed caisson bearing pier and structural foundation device
US5622015A (en) * 1995-04-12 1997-04-22 Collins; James S. Method and apparatus for consolidating earth and anchor setting device
EP0758699B1 (fr) * 1995-07-31 2001-10-17 Dipl.Ing. Helmut Hemmerlein GmbH & CO. Bau KG. Procédé d'installation de pieux côniques, pieux correspondants, et fondation à pieux ainsi obtenue
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110750901A (zh) * 2019-10-21 2020-02-04 成都理工大学 基于离散元模型的土体扰动范围判断方法
CN110750901B (zh) * 2019-10-21 2021-09-14 成都理工大学 基于离散元模型的土体扰动范围判断方法

Also Published As

Publication number Publication date
GB2384510A (en) 2003-07-30
CA2473912A1 (fr) 2003-07-31
GB0201513D0 (en) 2002-03-13
GB2384510B (en) 2005-06-22
WO2003062540A1 (fr) 2003-07-31
US20050117975A1 (en) 2005-06-02
HK1054976A1 (en) 2003-12-19

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