You are here:

Construction & Contractors/foundation column on river rock bouldeR

Advertisement


Question
plot image
plot image  

plot image 2
plot image 2  
HI
I AM FROM HYDERABAD INDIA I PURCHASE LAND NEAR MUSI RIVER IN HYDERABAD THAT LAND FILLED WITH ROCK BOULDER UP 15 FEET COMPLETE AREA IT IS SMALL AND LARGE BOULDERS MY QUESTION IS HOW TO CONSTRUCT FOOTING COLUMN ON THAT PART OF AREA PLEASE ANSWER ME IN DETAIL ATTACH PICTURE ON FILE
THANK U
MIR KHAN

Answer
In my opinion that material is uncontrolled rock fill probably disposed from another construction site elsewhere.  Between the boulders is loose dirt.  Under load from shallow footings the dirt will rearrange and the boulders will shift.  As such the material should not be built upon until it is removed and recompacted, otherwise large differential settlements are likely.  If it is a small site and you have sufficient funding you may be able to grout the fill, in other words, permeate the spaces between the loose boulders with cement grout that will support the boulders so they cannot shift, and then place spread footings, but this will entail drilling holes all through the loose fill to solid, native material and injecting the grout through those holes, under pressure.  Drilling holes that will stay open is difficult in this kind of material.  Another option would be to drill holes and place reinforced concrete piles but for that, in this kind of ground, you will need a casing advancement method such as ODEX.  There are specialty foundation contractors who will do this kind of work but it is expensive.  It is probably not as expensive as the grouting option.

I am sorry to tell you this but if you expect the structure to be safe and to perform, you are going to have to correct this loose ground condition.

Construction & Contractors

All Answers


Answers by Expert:


Ask Experts

Volunteer


Robert Cummings, P.E.

Expertise

I can answer questions related to rock blasting, rock and soil excavation (such as tunnels and highway cuts), stability of such excavations, and foundations in rock and soil. I can also answer questions related to geology and mining.

Experience

30+ years as a geotechnical engineer and minerals engineer. Active consulting practice in rock blasting, geotechnical engineering, and rock mechanics for mining and heavy construction.

Organizations
Society of Mining Engineers, Deep Foundations Institute, Association of Engineering Geologists, and International Society of Explosives Engineers.

Publications
Mining Engineering, AEG Bulletin.

Education/Credentials
BS and MS Geological Engineering

©2016 About.com. All rights reserved.