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Question 12:

On 5 May 2014, we received a heart-breaking email. Here is part of the content:

I received news that my friend and his family were buried in the recent landslide in Afghanistan, many others have been frantically removing the debris and earth to search for survivors. But till this date, we still receive no news of him. There were similar landslides in the past, is it true that the same location is not suitable for habitation?

 

Our Reply:

We have been following the landslide news of Afghanistan and we are saddened by the fact that there are more than 2000 casualties / missing people when many of you have been searching round the clock for survivors. We would like to send our condolences to all the families of the victims and we hope that you know that our prayers reach out to you and the people are not alone in the face of such disaster. We understand that aids are flowing in but slow due to the difficult terrain. Please keep in touch and let us know if you need our assistance as we would be able to forward your requests to other parties whom we think would be able to help.

 

When a landslide happens to a slope, it implies that there are some kind of slope stability problems in the area. This means that there should be NO housing development to be built on the top of the slope, on the slope or below the slope until adequate Ground Improvement Measures be taken to ensure that similar landslide problems would not occur in the future.

 

What would a Responsible Engineer do before he / she decides whether houses could be built on or around the slope area?

Step 1: Comprehensive Slope Stability Analysis to be performed based on the existing earth characteristics and strength.

Step 2: Decide on the type of Ground Improvement Measures to be taken to increase the strength of the earth, on and around the slope area.

Step 3: Perform the Ground Improvement Measures and conduct tests on the treated earth to ensure that the Soil Treatments which have been conducted can serve its purpose.

Step 4: Use the tested soil parameters to design building foundations based on new Slope Stability Calculations.

 

What are the Ground Improvement Methods normally being adopted?

The Ground Improvement Methods to be adopted would depend on what kind of buildings going to be built on or around the slope. In the case of no new construction, Ground Improvement Measures may still be needed to ensure that no further landslide would happen.

Here are some possible treatments to the soil depending on the existing earth characteristics / soil matrix:

a. Particulate Grouting, Chemical Grouting, Pressure injected Lime, Displacement Grout, Jet Grouting,

b. Remove and Replace, Structural Fills, Mix-In-Place Piles and Walls,

c. Vibro-Replacement Stone and Sand Columns, Root Piles, Soil Nailing, Strips Grids and Membranes and possibly others.

We would not elaborate further as all of the aforesaid are specialist trade terms and only Engineers who are well-trained in this field could understand.

 

What to do next?

It is wise NOT to build any new developments after a landslide without comprehensive Soil Improvement Measures taken as the same could happen again without warning. The people should request the Authorities to treat the Area and to strengthen the earth before new construction should begin, so as to avoid possible loss of lives and properties in the future.

 

Please contact us if you need further clarification or help.

We hope that the Families of the Victims would slowly recover, go on in life and be assured that the dead victims are now being well taken care by God who is just and would reward all of us base on the good we have done in this life.

Lets unite and work together to build a better world!

 

Drafted by:

Er. Goh Cheow Leng Maria

(First drafted on 6 May 2014)

 

 

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