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Viaduct I Failure, Caracas – La Guaira Highway, Venezuela Ali Jabalameli Yaút Peña Pattanun Chanpiwat.

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Presentation on theme: "Viaduct I Failure, Caracas – La Guaira Highway, Venezuela Ali Jabalameli Yaút Peña Pattanun Chanpiwat."— Presentation transcript:

1 Viaduct I Failure, Caracas – La Guaira Highway, Venezuela Ali Jabalameli Yaút Peña Pattanun Chanpiwat

2 Introduction  Viaduct No.1 was completed in 1953.  The main part of structure consist of three parallel arch ribs of a hollow box type, with a hinge to hinge span of 152 m and a height of 70 m.  The southern pile was founded on vertical concrete shafts and three inclined concrete piles.  The pilaster and the arch on the northern side were founded on a raft foundation.

3 Behaviour of the southern slope 1953-1987  Landslide in 1974 that affected many low income houses.  In 1981 a landslide occurred in the upper part of the slope, located 250 m south of the Viaduct.  An asphalt bump formed along southern abutment on April 1987.  Geotechnical investigation, including photogeology, borings and slope instrumentation was carried out. 1974 Landslide

4 Photogeology  Aerial photographs carried out between 1936 and 1983 were carefully examinated.  Scarps, stepped topography and color tone contrast of the slope were evidence of an ancient, 500 m long landslide.  A meander in the channel of Tacagua creek at the bottom of the slide served as physiographic evidence of the slope movement.

5 Geology and exploratory borings (prior to 1987) Material of the slope: Colluvial material derived from ancient landslides. Rock Mass: Limestones interfoliated with calcaroues mica schists, quartzites and some amphibolites. Main Geological Feature: East - West Fault. Considered geologically active and responsible for some earthquakes in central Venezuela. Strike Parallel to strike of slope. Dip Direction 15-40° North Colluvium Limestones

6 Emergency works in 1987 245 passive anchors. 1 3/8” diameter grouted bars. 30 – 36 m long. 3 m into rock. 20 prestressed cable anchors. Only constructed to divert the landslide thrust from the bridge. On both sides: On the south abutment: Opening of the expansion joints to reduce the positive bending moment on the northern side.

7 Geological Exploration 1987 - 1988: Observations Movement of rock blocks along foliation planes at low dips (10°-20°). Tectonic slickensides. Local fault breccias. Evidence of the intense tectonic history of the area. Fault Breccia 50 m wide in a direction parallel to the displacement vector of the landslide. Two inclinometers revealed the presence of a well defined failure surface

8 Surface Movement Monitoring A)3 bench marks opposite side of valley B)15 control reference points on the surface C)56 control points on the deck D)4 control points on pilaster s and abutments Instrumentation

9 Prediction of failure Prediction based on * Fukuzono (1985 ) and Voight (1989a,b) *Ration between rate of soil movement & rate of arch closing Method *collect rate of soil movement (cm/month) *plot the invert of velocity against time (month/cm)

10 Effect of landslide thrust on Viaduct No. 1 Why does it fail? *Slope movement of reactive ancient landslide *Moving of Viaduct No.1 southern side increase distress in the structure *The structural geologic setting influence and rainfall infiltration *Structure is designed to resist compression stress not for tension forces Cause Action *Replacement of northern concrete abutment and piers with steel trusses with rollers (allow to move freely ) *Replacement of original concrete rockers with steel struts (resist tension) *Construction of a cable system placed in U shape grabbing between two piers ( support of transverse shear failure & releasing energy stored in the decks)

11 Series of Actions August 2005December 2005

12 Question ?

13 References Salcedo, Daniel. "Behavior of a landslide prior to inducing a viaduct failure, Caracas-La Guaira highway, Venezuela." Engineering Geology. 109. (2009): 16-30. Print.

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