Foundation design to Eurocode 7

1 Foundation design to Eurocode 7. Dr Andrew Bond (Geocentrix). Outline of talk z Overview of Eurocode 7. z New principles for geotechnical design z Impact on retaining wall design z Impact on pile design z Benefits of Eurocode 7. This presentation is available from: 2006 Geocentrix Ltd. All rights reserved 2. 1. Foundation design to Eurocode 7. Overview of Eurocode 7. Structural Eurocodes suite z Main resistance Eurocodes: z Same Principles, different Rules z Eurocode 7: z Same Rules, different Principles 2006 Geocentrix Ltd. All rights reserved 4.

2 2. Eurocode 7 timetable z Prospective standards for provisional application (ENVs). z ENV 1997-1: 1994 General rules z ENV 1997-2: 1999 Field testing z ENV 1997-3: 1999 Lab. testing z Full European standards (ENs). z EN 1997-1 published December 2004. z prEN 1997-2 available 2005. z EN 1997-2 to be published late 2006? 2006 Geocentrix Ltd. All rights reserved 5. Contents of EN1997-1 General rules Contents of EN 1997-1. 1 General 2 Basis of Annexes geotechnical design 12 3. Embankments Geotechnical data 9 Retaining structures 4 Supervision 5 Fill, 8 Anchorages dewatering, etc 7 Pile 10 Hydraulic foundations failure 11 Overall 6 Spread stability foundations 2006 Geocentrix Ltd.

3 All rights reserved 6. 3. Contents of prEN 1997-2. design assisted by field and laboratory testing Contents of prEN 1997-2. 2 Planning of 6 Ground 1 General ground Investigation investigations Report Annexes 3 Soil and rock sampling and groundwater measurements 5 Laboratory 4 Field tests tests on soil in soil and rock and rock 2006 Geocentrix Ltd. All rights reserved 7. Foundation design to Eurocode 7. New principles for geotechnical design 4. design requirements z (1)P For each geotechnical design situation it shall be verified that no relevant limit state is exceeded z (4) Limit states should be verified by z Use of calculations z Adoption of prescriptive measures z Experimental models and load tests z An observational method 2006 Geocentrix Ltd.

4 All rights reserved 9. Geotechnical categories GC Includes design requirements design procedure 1 Small and Negligible risk of Routine design &. relatively simple instability or ground construction methods structures with movements negligible risk Ground conditions known No excavation below water table 2 Conventional Quantitative geotechnical Routine field & lab types of structure data & analysis to ensure testing & Foundation fundamental Routine design &. with no requirements are satisfied execution exceptional risk or difficult soil or loading conditions 3 Structures or Use alternative provisions and rules to those in parts of Eurocode 7.

5 Structures not covered above 2006 Geocentrix Ltd. All rights reserved 10. 5. Example geotechnical categories GC Includes Examples 1 Small and None given in Eurocode 7. relatively simple structures with negligible risk 2 Conventional (19) Spread; raft; & pile foundations ; walls &. types of structure other structures retaining or supporting soil or & Foundation water; excavations; bridge piers & abutments;. with no embankments & earthworks; ground anchors &. exceptional risk other tie-back systems; and tunnels in hard, non- or difficult soil or fractured rock and not subjected to special water loading conditions tightness or other requirements.

6 3 Structures or (21) Very large or unusual structures;. parts of structures involving abnormal risks, or unusual or structures not exceptionally difficult ground or loading conditions;. covered above structures in highly seismic areas; and structures in areas of probable site instability or persistent ground movements that require separate investigation or special measures 2006 Geocentrix Ltd. All rights reserved 11. Ultimate limit states for stability 2006 Geocentrix Ltd. All rights reserved 12. 6. Ultimate limit states for strength 2006 Geocentrix Ltd.

7 All rights reserved 13. Limit states GEO and STR. z Definition of limit state GEO. z Failure or excessive deformation of the ground, in which the strength of soil or rock is significant in providing resistance z often critical to sizing structural elements in foundations or retaining structures z Definition of limit state STR. z Internal failure or excessive deformation of the structure or structural elements in which the strength of structural materials is significant in providing resistance z includes (for example) footings, piles, and basement walls 2006 Geocentrix Ltd.

8 All rights reserved 14. 7. Structural verification of strength (STR). Verification of limit state STR. Actions and effects Material properties and resistances Representative Characteristic actions material Frep properties Xk design material Partial factors design actions Partial factors F properties M. Fd Xd Structural analysis Stress analysis design effect of design actions resistance Ed Rd Verify Ed Rd 2006 Geocentrix Ltd. All rights reserved 15. Allowable stress design procedure 2006 Geocentrix Ltd. All rights reserved 16. 8. Verification of strength for GEO/STR.

9 2006 Geocentrix Ltd. All rights reserved 17. design Approaches z (1)P The manner in which [GEO and STR. are applied] shall be determined using one of three design Approaches z design Approaches are ONLY relevant to limit states STR and GEO. z NOTE 1 Particular design Approach to be used may be given in the National Annex z UK/Denmark prefer DA1. z Germany/France prefer DA2. z Some countries will allow a choice 2006 Geocentrix Ltd. All rights reserved 18. 9. design approaches for STR/GEO. Structure design Approach 1 2 3. Combination Combination 1 2.

10 Axially loaded Actions Resistances Actions & Actions &. piles and resistances material anchors properties &. resistances Other Material structures properties Slopes Effects of Effects of actions & actions &. resistances material properties &. resistances 2006 Geocentrix Ltd. All rights reserved 19. Foundation design to Eurocode 7. Impact on retaining wall design 10. Contents of Section 9. General Limit states Actions, geometrical data and design situations design and construction considerations Determination of earth pressures Water pressures Ultimate limit state design Serviceability limit state design 2006 Geocentrix Ltd.