THIRTYFIVE YEARS OF APPLICATION OF MICROPILES IN AUSTRIA

Transcription

1 THIRTYFIVE YEARS OF APPLICATION OF MICROPILES IN AUSTRIA Manfred FROSS Dipl.-Ing. Dr.techn.,., Ass.Prof.i.R. Geotechnical Consultant Vienna, 1

2 CONTENTS Introduction Types of micropiles used in, 8 examples of applications of micropiles in between 1971 and 2005 Activities in to promote the use of micropiles Closing remarks 2

3 Types of micropiles used in in the period first from 1971 until about

4 8 examples of application of micropiles in ) Kläranalage GÜSSING/Burgenland 1971/72 2) ÖBB-Brücke Brücke Südtirolerplatz U U 1/Vienna 1972/73 3) Haus REISCH Schwarzsee bei KITZBÜHEL/Tyrol Tyrol 1974/75 4) Halle DONAUPLASTIK Auhof/Vienna 1976/77 5) Freibad WILDSCHÖNAU/Tyrol 1979/80 6) Waldsiedlung BISAMBERG/Lower 1992/94 7) Kurzentrum BAD SAUERBRUNN/Burgenland 2001/02 8) Tunnel RANNERSDORF S 1/Lower 2004/05 Examples 1 to 3: Type Wurzelpfahl, examples 4 to 6: Type GEWI-piles piles, Example 7: type DUKTIl-piles piles, example 8: GEWI-tension tension-piles. 4

5 EXAMPLE No. 1 A new sewage tank of Kläranlage GÜSSING/Burgenland (10 m diameter,, 13 m high) was built without any soil investigation, founded on a spread foundation (slab). After a first test filling with water an inclination with a differential settlement of 25 cm occured. Supplementary investigation borings showed a layer of peat in one borehole in a depth of 7 m to 8 m. Rehabilitation (underpinning( underpinning) ) was performed by 16 micropiles (type Wurzelpfahl), the first application of micropiles in, execution in winter

6 Section through the sewage tank with differntial settlements of 25 cm 6

7 Results of 2 supplementary borings 7

8 Rehabilitation of the sewage tank with 16 micropiles (type Wurzelpfahl ) 8

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10 EXAMPLE No. 2 The footings of a railway bridge in VIENNA close to Südbahnhof were strengthened by micropiles (type Wurzelpfahl) prior to tunneling works of Vienna metro line U 1 (tunnel( construction of the 2 tubes with BADE shield machine) ) in 1972/73. It was the first application of micropiles for a public building in a cooperation of the building authorities of Vienna with n railways (ÖBB). Displacements during piling and tunneling works were only 4 mm to 7 mm. 10

11 Cross section through the railway bridge and the metro tunnels of U 1 Time settlement behaviour during piling and tunneling works 11

12 EXAMPLE No. 3 A new house (double bungalow) near KITZBÜHEL/Tyrol Tyrol close to lake SCHWARZSEE built 1974 was founded on a spread foundation (reinforced concrete slab d = 30 cm) on a compacted fill of coarse material. No soil investigations were done. Just before finishing this house differential settlements of about 35 cm (!) occured. Supplementary soil investigation showed a lense-like like layer of very soft peat between a depth of 3 m to 5 m. Rehabilitation (underpinning( ) was performed 1975 by 21 micropiles (type Wurzelpfahl), bored through the foundation slab. 12

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14 Time-dependant settlement-behaviour of the building before and after the underpinning with micropiles 14

15 EXAMPLE No. 4 An new industrial building in Vienna (prefabricated reinforced concrete elements) founded on rather small single footings showed differential settlements already during construction work. A loose fill of course soil material (sandy( gravel) ) was not recognized as a fill because of insufficient in-situ soil investigation. Rehabilitation (underpinning( underpinning) ) was performed by micropiles 1976/77. It was the first application of the type GEWI-pile in. 15

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17 Equipment for the installation of the GEWI-piles in 1976/77 17

18 EXAMPLE No. 5 Freischwimmbad WILDSCHÖNAU/Tyrol built 1978/79 without any soil investigation on spread footings only with an exchange of the upper soil layers against a very coarse fill of crushed rock material. 2 swimming pools showed differential settlements of more 25 and 30 cm, a restaurant building about 18 cm. Supplementary investigation borings showed layers of peat to a depth of 12 m below the surface. Rehabilitation of the swimming pools (stainless steel) was performed by driven precast reinforced concrete piles, rehabilitation (underpinning)) of the restaurant building was performed by micropiles (type GEWI-pile with double corrosion protection) ) in winter 1979/80. 18

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20 Time-dependant settlement behaviour before and after underpinning with GEWI-piles piles. 20

21 Installation of the GEWI-piles in winter 1979/80 21

22 EXAMPLE No. 6 Waldsiedlung BISAMBERG/NÖ north of Vienna, built 1992 without any soil investigation. 2 new houses on spread foundations showed differential settlements of 12 cm and 5 cm and a lot of cracks. This settlements were caused by a small natural trench filled with loose, partly organic material (roots( etc.) without any compaction. Rehabilitation (underpinning( underpinning) ) was performed 1994 by micropiles (type GEWI-pile pile) with special construction of the pile heads with additional reinforcement (against bending moments) ) and HILTI-dowels sticked with a paste of synthetic resin to the existing walls. 22

23 Ground plan of the houses 23

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25 EXAMPLE No. 7 Foundation of a new building of sanatorium Kurzentrum Bad Sauerbrunn/Burgenland on DUKTIL-Piles 2001/2002. Soil conditions were rather difficult: young deposits with intermediate layers of peat an soft silt. Higher existing buildings were founded on large diameter bored piles about 25 years ago. A flat building of this sanatorium was founded on a spread foundation and had to be underpinned by micropiles (type ROPRESS-Pile ) after differential settlements of more than 12 cm already soon after construction in

26 Elements of the DUKTIL Pile, driving machine with high speed - hydraulic hammer 26

27 DUKTIL Pile (displacement pile) diameters, thickness of walls of the tubes, design loads 27

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30 EXAMPLE No. 8 Tunnel Rannersdorf, about 1,9 km in length, part of new highway S 1 Wiener Außenring Schnellstraße in the south and southeast of the city of Vienna, close to Vienna International Airport Schwechat. Construction of the tunnel in open excavation with sheet pile walls, underwater concrete slab, stabilized against uplift due to high groundwater by micropiles (type GEWI tension piles). Execution of more than 1200 GEWI piles 2004/2005. The higway was opened for traffic on April 28th,

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33 Tunnel Rannersdorf, longitudinal geological-geotechnical geotechnical profile 33

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35 Cross-sections sections of the tunnel 35

36 Model according to ÖNORM B :1999 2: , Section 8, Fig.16 c) 36

37 Model according to DIN 1054: , 01, Section 8.5.4, Fig.2, for a single tension pile 37

38 Models according to EUROCODE 7-1, Section 7, Fig

39 Comparison of the results of the design length of the GEWI-tension tension-piles 39

40 Test device for load tests to prove the pull out resistance of GEWI-piles 40

41 Pile load test proving the pull out resistance of a GEWI-tension pile 41

42 Result of a pull out test 42

43 Under water excavation 43

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46 Section of the ground plan for the installation of the GEWI-piles 46

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49 Diving devices 49

50 Divers working 50

51 Under water concreting 51

52 Under water concrete slab and GEWI-pile heads 52

53 Cleaning and compensation concrete 53

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55 Reinforcement of the tunnel base 55

56 CLOSING REMARKS now has a tradition of application of micropiles of 35 years. We have a wide range of types of micropiles, both bored piles and displacement piles. We have several contractors offering these different types of micropiles. These contractors are organized within VÖBU (n( association of special foundation contractors), affiliated to EFFC (European Federation of Foundation Contractors). ISM - International Society for Micropiles is not yet known in, but I will try to do my best to bring this new society to the attention of all n geotechnical engineers working in different fields (science, universities, authorites, designers and contractors). 56

57 Activities in in 2005 to promote the use of microplies according to European Standard ÖNORM EN

58 Many thanks for your kind attention! 58