×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Causes of Lanslide

Causes of Lanslide

Causes of Lanslide

(OP)
We have a pipeline project on a 60 degree slope mountain. We hired a specialist to evaluate the factor of safety which they provided equal to 2.31. Based on my site inspection the soil is dominantly composed of loose gravel. Thickness of soil is 3-6m from boreholes. Bedrock consiting of DIORITE. Climate is tropical. traces of landslide were visible near the area is near the river.
QUESTION:  
1. Based on experience is the contractor correct?
2. What causes landslide?
3. Circular and Planar failure was used for evaluation?
4. References?

thanks

RE: Causes of Lanslide

Be careful of working on mountainous slopes. A 60 deg slope giving a factor of safety that high?  How deep will you pipeline be buried - into rock or within the "gravel".  If you take "loose gravel" - infinite slope (shallow translational slides) would be the most critical.
see:  www.cedd.gov.hk/eng/publications/guidance_notes/doc/tgn10.pdf
 

RE: Causes of Lanslide

(OP)
BigH the pipeline is proposed to be exposed outside..pipeline slippers or its foundation is approx. 2m deep at 250 bearing capacity, pipeline dia is 2.0.

 

RE: Causes of Lanslide

with 60° slope angle it is difficult that material is loose.
it is better foundation with collar and (no excavation) and micropile or similar for staibility. the value of 2.31 was performed from geotecnical data?

RE: Causes of Lanslide

Question Number 2 as to causes can have several answers.  Using your geotechnical info may provide some answer, such as weak layer.  However, did the evaluation consider you weather and possibly some saturation of the site at times?  In my experience saturation is generally in the picture when failure occurs.

Also, is that 60 degree a measurement or someone's guess?  Slopes may seem steeper than the measurement says.

Slides in the area would tell me that 2.31 is wrong.

RE: Causes of Lanslide

(OP)
i agree with you oldestguy since the climate is tropical and the type of soil is loose difinitely it will surely fail. they are using "geoslope" software to evaluate the stability based on the boreholes and soil parameters they gathered on site (cohesion, angle of internal friction, grading, water table etc) thats why we are currently hiring another company to conduct another slope stability on the area. thanks

RE: Causes of Lanslide

Don't forget seismic effects in your translational sliding model.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources