Abstract:
Collapsible soils have known to cause major damage to structures and facilities all over
the world. These soils which have excellent strength and stiffness properties in dry
conditions undergo a sudden reduction in volume when exposed to water. Buildings in
Risalpur cantonment show severe signs of distresses in form of extensive cracking,
settlement and at times tilting. Geological evidence show that soil deposits in Risalpur
are mostly alluvial and loess deposits which together with hot and humid climate favors
formation of collapsible soils. A study has been conducted to investigate the possibility of
collapsing soils as a probable cause of cracking and settlement of buildings. Soil was
characterized up to a depth of 20 feet, i.e., zone of influence of shallow foundations.
Existing criterion for identification of collapsible soils indicated the presence of
collapsible soils up to the depth of investigation. Detailed investigations were carried out
to using single oedometer tests, standard penetration tests, unconfined compression tests
and plate load tests. All these tests indicated severe collapse potential especially at 4 feet
depth. For example, single oedometer test at 4 feet depth indicated a collapse potential of
seventeen percent when the specimen was flooded under a load of 200kPa.
A preliminary study was also conducted to ascertain the feasibility of use of stone
columns to mitigate collapse of Risalpur soil. The stone column improved the load
carrying capacity and reduced the settlement under flooded conditions; however, more
detailed study is required to determine the optimum area ratio for most economical and
efficient stone columns
