A study on the engineering behaviour of Nairobi subsoil

Abstract

Nai r obi C i t y is un derl ai n by vol cani c m a t e ri al s t h at resul t ed fr om t h e form at i on of t h e ri ft val l e y . Som e of t h e challenges tha t face design of structures i n the city include: the nee d to devel op st ruct ures in a r eas with poor site co nd itio ns; d i stress in stru ctures th at co u l d b e related to fou n d a tion con d i tio n s ; en co un ter o f u n e xp ected sub s o il co nd itio ns even a f t e r ca rr y i ng o u t s o m e geot ec hni cal i n vest i g at i o ns, a nd; devel opm ent o f de fect s re l a t e d t o ad jace nt dee p e x cava t i o n . Th e ob j ecti v es of t h is stud y were: t o i n v e stig ate th e qu a litativ e an d q u an titativ e properties of sub s urface m a terials , to est a bl i s h t h e engi neeri ng pr o p ert y vari at i o n s and t o p r o v i de p r o p e rties th at rep r esen t th e b e st esti mates. In formatio n av ailab l e fo r t h is stud y in clu d e d ; Atterb erg li m its, g r ad i n g, con s o lid atio n, swell and co llap s e, tria xial shear a nd direct sh ear, po in t load and un co nfin ed co m p ressiv e streng t h . Failu re in v e stig atio n and resistiv ity su rv ey were carried ou t to fill th e g a p s in th e av ailab l e in fo rmatio n . Th e r