Anaheim hills landslide
This presentation is the property of its rightful owner.
Sponsored Links
1 / 14

Anaheim Hills Landslide PowerPoint PPT Presentation


  • 308 Views
  • Uploaded on
  • Presentation posted in: General

Anaheim Hills Landslide. ‘Avenida de Santiago’ January 17th 1993. Introduction. Southern California, the Orange County Winter storms cause widespread slope failures Disrupt infrastructure Excess rainwater causes rising groundwater levels Re-activates ancient landslide

Download Presentation

Anaheim Hills Landslide

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Anaheim hills landslide

Anaheim Hills Landslide

‘Avenida de Santiago’

January 17th 1993


Introduction

Introduction

  • Southern California, the Orange County

  • Winter storms cause widespread slope failures

  • Disrupt infrastructure

  • Excess rainwater causes rising groundwater levels

  • Re-activates ancient landslide

  • ‘Avenida de Santiago’ most high profile


Why did it occur

Why did it occur?

  • North-facing hillside topography

  • Geology

  • Rising Groundwater

  • Human error


Geology

Geology

  • Northward dipping section

    • Sandstone and Siltstone (Puente Formation)

    • Miocene age

  • Bedding dips 7° to 25° to North

  • Strikes range NE to NW

  • Failure in Puente Formation

    • Parallel to bedding

  • Sandstone

    • Medium to Coarse grained

    • Poor cemented

    • Weak

    • Inter bedded with Siltstone


Geology1

Geology

  • Compressional uplift of tertiary sedimentary section due to blind thrust faults

  • San Andreas fault

    • Strike slips and thrust faults

    • Multiple earthquakes

    • Late Quaternary time contributes to landslide


Weather

Weather

  • Intense rainfall December 1992 and January 1993

    • Equal to average annual rainfall (38cm)

  • Raised groundwater level in landslide mass


Human error

Human Error

  • Early Geotechnical Investigation

    • No groundwater evaluation

      • Piezometer

    • Poor borehole investigations

      • Few widely spaced and shallow

  • Responsive, not proactive

    • Local authorities authorised Geological Investigation upon observation of cracks

  • Neglected evidence of previous landslides


The landslide

The Landslide

  • Soil Slumps and Soil Block slides move at 2/3cm per day

  • Translational

    • 400m wide x 600m long

  • After management solutions slide deemed stationary by mid-April 1993


The landslide1

The Landslide

  • Cracks and Fissures developed at head

  • Compressional features damaged infrastructure lower down slope

  • Immediate Engineering implications


Geotechnical investigation

Geotechnical Investigation


Geotechnical investigation1

Geotechnical Investigation

  • Ridge Top Graben at LD-3 source of landslide

  • Slip occurs at Sandstone bedrock as identified by borehole logs


Engineering prevention strategies

Engineering Prevention Strategies

  • Dewatering to control groundwater level

  • Removal and recompaction of potentially compressible soils

  • Complete or partial removal of ancient landslides

  • Stabilisation of potentially unstable cut slopes

    • Case study $2.9 million for one house!

  • Specific structure foundation designs


Dewatering

Dewatering

  • GHAD final solution

  • 30 million gallons water per year

  • Dewatering wells and horizontal drains

  • Lower and control groundwater levels

  • Substantially improved stability of landslide mass

  • Constantly monitored


Conclusion

Conclusion

  • Re-activation of Ridge-Top Graben by seismic shaking & rising groundwater

  • Dewatering is a ‘stop gap’

  • $3.5 million budget

  • Constant road resurfacing

  • New fissures appeared in 1998

  • Escape route plan


  • Login