Preliminary findings field visit Balakot & Muzzafarabad March 2006

Transcription

1 Preliminary findings field visit Balakot & Muzzafarabad March 2006 Mark van der Meijde Siefko Slob INTERNATIONAL INSTITUTE FOR GEO-INFORMATION SCIENCE AND EARTH OBSERVATION

2 Damage assessment and possible relation with geology gy and geomorphology gy Balakot Muzaffarabat

3 Balakot

4 Main bridge Horizontal displacement (1m) direction (Southwards) foundation & bridge-deck remain however intact

5 Footbridge Horizontal displacement of foundation p (southwards)

6 Slope failure

7 Structural building failure Failure of pillarbeam connection

8 Damage due to irregular lay-out

9 Damage due to wrong detailing Exposed reinforcement Insufficient lateral reinforcement

10 Damage due to wrong detailing Insufficient connection between pillars and horizontal beams

11 Damage due to wrong detailing Insufficient connection between pillars and horizontal beams

12 Failure of supporting walls due to inferior concrete quality Too large quantities of gravel Presence of silt- size particles

13 Foundation failure Due to slope movement?

14 Or. soft storey?

15 Complete devastation on top of hill (West of river)

16 View on hill (from the East)

17 Tentative conclusions for Balakot - for discussion (1) Damage in West side of river combination of Poor construction o + shaking Possible slope failure (buildings situated on steeper slope, likely loose unconsolidated poorly sorted colluvium deposits)

18 Tentative conclusions for Balakot - for discussion (2) Total devastation on hill (Eastside) Larger damage than other areas in town Possibly due to topography amplification effect

19 Tentative conclusions for Balakot - for discussion (3) Damage in Flat alluvial plains possible combination of: Normal soil amplification 2D and 3D amplification effects due to trapped body waves in valley geometry Surface waves (Love & Rayleigh waves)

20 Muzaffarabad

21 Damage at building of Dept. of agriculture Failure of supporting wall due to bad detailing; weak cement bonding between stone bricks

22 Weak bonding - detail

23 Failure of supporting walls

24 Failure of supporting wallls Double wall Inner and outer cemented wall Space filled with debris Lack of lateral support between inner and outer walls

25 Observed poor quality concrete bricks Many weak discontinuities in bricks Clay, organic material Non-optimal use of cement, gravel, sand mixture

26 Failure of weak columns: Columns are cemented brick No steel reinforcement Have no purpose, ornamental? Unnecessary ornamental additions should be avoided

27 Detailing Improper p use of steel reinforcement Outside of wall Not continuous Merely to attach roof?

28 Detailing Utility lines embedded just at surface of wall create potential lines of weakness along which shearing can take place

29 Old city centre Failure of tower of mosk

30

31 Column-beam failure Maybe lack of y bonding Maybe insufficient steel reinforcement Maybe poor quality concrete Most likely combination of factors

32 Increased damage near slope.

33 Soft storey

34 Failure of wall and columns due to horizontal shearing forces

35 Damage related to geology, geomorphology? gy Very hard to say, maybe not very relevant, listening to previous conclusions Seems like devastation is larger near the steep slope of river bank, e.g.: campus site site effect?

36 Comment from Mr Upadhyay from NSET: Much of the damage could have been avoided if only proper construction would have taken place

37 Key question - who to blaim? Who is/are responsible for the design and construction? Design: Geotechnical engineer Seismologic engineer Architect Structural engineer Construction: Architect Structural t engineer Site supervisor/engineer Mason/construction worker