BS EN 14199:2015
$198.66
Execution of special geotechnical works. Micropiles
Published By | Publication Date | Number of Pages |
BSI | 2015 | 66 |
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.
This European Standard is not applicable to driven piles, the execution of which is governed by EN 12699 .
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):
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uniform cross section (straight shaft); or
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telescopically changing shaft dimensions;
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shaft enlargements; and/or
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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):
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single micropiles;
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micropile groups;
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reticulated micropiles;
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micropile walls.
1.5 The material of micropiles covered by this European Standard can be:
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steel or other reinforcement materials;
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grout, mortar or concrete;
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a combination of above.
1.6 Micropiles can be used for:
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working under restricted access and/or headroom conditions;
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foundations of new structures (particularly in very heterogeneous soil or rock formations);
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reinforcing or strengthening of existing structures to increase the capacity to transfer load to depth with acceptable load settlement characteristics, e.g. underpinning works;
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reducing settlements and/or displacements;
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forming a retaining wall;
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reinforcing of soil to form a bearing and/or retaining structure;
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improving slope stability;
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securing against uplift;
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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 |