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BS EN 14199:2015

$198.66

Execution of special geotechnical works. Micropiles

Published By Publication Date Number of Pages
BSI 2015 66
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1.1 This European Standard establishes general principles for the execution of micropiles.

They are for drilled piles constructed using a drilling tool with a diameter less than 300 mm.

NOTE 1

This European Standard is not applicable to driven piles, the execution of which is governed by EN 12699 .

NOTE 2

For a definition of shaft diameter see 3.3.

1.2 Micropiles are structural members to transfer actions to the ground and can contain bearing elements to transfer directly or indirectly loads and or to limit deformations. For examples of micropiles see Figure 1, Figure 2 and Figure 3. Their shaft and base resistance can be improved (mostly by grouting) and they can be constructed with (see Figure 4):

  • uniform cross section (straight shaft); or

  • telescopically changing shaft dimensions;

  • shaft enlargements; and/or

  • base enlargement.

1.3 Other than practical considerations, there are no limitations regarding, length, inclination (definition of inclination, see Figure 5), slenderness ratio or shaft and base enlargements.

1.4 The provisions of this European Standard apply to (see Figure 6):

  • single micropiles;

  • micropile groups;

  • reticulated micropiles;

  • micropile walls.

1.5 The material of micropiles covered by this European Standard can be:

  • steel or other reinforcement materials;

  • grout, mortar or concrete;

  • a combination of above.

1.6 Micropiles can be used for:

  • working under restricted access and/or headroom conditions;

  • foundations of new structures (particularly in very heterogeneous soil or rock formations);

  • reinforcing or strengthening of existing structures to increase the capacity to transfer load to depth with acceptable load settlement characteristics, e.g. underpinning works;

  • reducing settlements and/or displacements;

  • forming a retaining wall;

  • reinforcing of soil to form a bearing and/or retaining structure;

  • improving slope stability;

  • securing against uplift;

  • other applications where micropile techniques are appropriate.

1.7 Deep mixing columns according to EN 14679 are not included in this European Standard. Columns constructed by jet grouting are covered by EN 12716 . Ground anchors are covered by EN 1537 .

PDF Catalog

PDF Pages PDF Title
4 Contents Page
6 Foreword
7 1 Scope
8 2 Normative references
9 3 Terms and definitions
13 4 Information needed for the execution of the works
4.1 General
14 4.2 Special features
15 4.3 List of activities
5 Geotechnical investigation
5.1 General
16 5.2 Specific requirements
17 6 Materials and products
6.1 General
6.2 Reinforcement and load bearing elements
6.2.1 Steel for reinforcement
6.2.2 Steel for load bearing elements
18 6.2.3 Other materials or grades of steel
6.3 Materials for grout, mortar and concrete
6.3.1 Cement
6.3.2 Aggregates
6.3.3 Water
6.3.4 Additions and admixtures
6.4 Grout
19 6.5 Mortar and concrete
6.6 Spacers, centralisers and other components
20 6.7 Coatings and corrosion protection compounds
7 Considerations related to design
7.1 General
21 7.2 Geometrical construction tolerances
7.3 Installation
7.4 Reinforcement and load bearing elements
22 7.5 Connecting elements
7.6 Corrosion protection of steel elements
23 7.7 Spacers and centralisers
7.8 Micropile enlargement
24 7.9 Connections to the superstructure
7.10 Spacing of micropiles
7.11 Special requirements for micropiles
8 Execution
8.1 General
25 8.2 Construction tolerances
8.3 Site preparation
26 8.4 Sequence of installation
8.5 Drilling
8.5.1 General
27 8.5.2 Use of flushing
8.5.3 Boreholes supported by casings
8.5.4 Drilling with segmental hollow stem augers
8.6 Enlargements
28 8.7 Reinforcement and load bearing elements
8.7.1 Handling and storing
8.7.2 Joints
Table 1 — Guidance on welding testing and inspection, minimum criteria for micropiles and micropile details in structural steels
29 8.7.3 Spacers and centralisers
8.7.4 Installation
8.8 Filling and grouting
8.8.1 General
30 8.8.2 Grout preparation
8.8.3 Borehole testing and pregrouting
8.8.4 Filling the borehole
8.8.5 Filling or grouting through a temporary casing
31 8.8.6 Filling or grouting through a load bearing element
8.8.7 Grouting during drilling
8.8.8 Multi-stage grouting
8.9 Concreting
8.9.1 Concreting in submerged conditions
8.9.2 Concreting through a segmental hollow stem augers
32 8.9.3 Concreting in dry conditions
33 8.10 Trimming of micropiles
34 9 Supervision, monitoring and testing
9.1 Supervision
9.2 Monitoring of micropile construction
35 9.3 Micropile testing
9.3.1 General
9.3.2 Static load tests
9.3.2.1 General
9.3.2.2 Static load tests on preliminary micropiles
36 9.3.2.3 Static load tests on working micropiles
9.3.2.4 Loading procedure
9.3.3 Dynamic load tests
9.3.4 Low strain integrity tests
37 10 Records
10.1 General
10.2 Records for the execution of construction micropiles
Table 2 — General information concerning the site
38 Table 3 — General information concerning the micropile construction
39 Table 4 — Schedule of as-built information to be provided as applicable
10.3 Records for micropile tests
40 11 Special requirements
41 Figure 1 — Typical components of micropiles
42 Figure 2 — Example of steel core pile
43 Figure 3 — Example of drilled end-bearing steel pipe micropile
44 Figure 4 — Examples of micropile shafts and bases
Figure 5 — Definition of inclination
45 Figure 6 — Examples of micropile structures
46 Figure 7 — Examples of base and shaft enlargements
47 Figure 8 — Filling borehole through tremie pipe (bearing element in place first)
48 Figure 9 — Filling borehole through drill rods or bearing element
49 Figure 10 — Filling borehole with temporary casing (no pressure)
Figure 11 — Grouting borehole with temporary casing with applied pressure
50 Figure 12 — Single step grouting through tube-à-manchettes
51 Figure 13 — Multi step grouting through tube-à-manchettes
52 Figure 14 — Single step grouting through tube-à-manchettes in succession
53 Annex A (informative) Execution methods of micropiles
Table A.1
54 Annex B (informative) Guidance on minimum cover (in mm) for bearing element of low strength steel for cast in situ micropiles
Table B.1
55 Annex C (informative) Borehole testing and pregrouting
56 Annex D (informative) Guideline for a record for micropiles
Table D.1
57 Annex E (informative) Degree of obligation of the provisions
64 Bibliography
BS EN 14199:2015
$198.66