dc.contributor.author | Otando, Simon Wanyonyi | |
dc.date.accessioned | 2013-05-09T12:04:05Z | |
dc.date.available | 2013-05-09T12:04:05Z | |
dc.date.issued | 1996 | |
dc.identifier.citation | M.Sc. (Geology) Thesis 1996 | en |
dc.identifier.uri | http://erepository.uonbi.ac.ke:8080/xmlui/handle/123456789/20839 | |
dc.description | Master of Science Thesis | en |
dc.description.abstract | This thesis work presents the results of geological and geotechrucal investigations carried
out in the Nairobi area. Kenya. The study was undertaken with the aim of obtaining and
providing information that could help in assessing the suitability, and capacity of the soils
of the study area. to support shallow foundation engineering structures. This information
could in turn assist in the design and construction 0;' projected shallow foundation
structures.
The study was centered on determining and, or establishing the various soil classes: and
their lateral extent, thickness and possible genetic origin Other aspects of the study were
aimed at establishing the position and nature of the bedrock, the general physiography of
the study area and the geotechnical characteristics of the soils.
The field investigations incorporated an integrated approach The methods used included
photo - interpretation. geological reconnaissance and mapping. and auger - boring and
disturbed soil samples collection.
The western and north - western parts of the study area are predominated by the dark red
friable clays and the red friable clays. Also found in this zone are the dark grey mottled
clays and the shallow yellow-brown to yellow-red friable clays. Minor and isolated
occurrences of shallow stony soils and peaty swamps are also found.
The eastern and south - eastern sections of the study area are covered mainly by the black
to dark grey clays and the dark greyish - brown calcareous clays. Also found but to a
lesser extent are the shallow yellow-brown to yellow-red friable clay s. shallow stony
soils and alluvium.
The laboratory analysis of the collected soil samples involved soil classification testing
(grain size analysis; natural moisture content; Atterberg limits: and free swell tests). More
elaborate soil testing procedures involved CD shear strength tests and subsequent soil
bearing capacity evaluation; and oedometer consolidation testing and subsequent
evaluation of soil compressibility and settlement characteristics. The results show the
mottled clays, the black clays and the calcareous cia; s to be of high plasticity and
apparently more expansive. In addition the clays exhibit limited strength and stability and
significant compressibility and settlement characteristics. Under normal conditions of
occurrence these clays are generally not suited for shallow foundation engineering
purposes.
On the other hand the low to medium plasticity shallow yellow - brown to yellow - red
friable clays exhibit some significant strength and stability and slightly limited
compressibility and settlement characteristics. However. the soils are generally limited in
depths and unsuitable for shallow foundation engineering purposes. The dark red clays
and the red clays are generally inactive and exhibit very limited expansive behaviour.
They represent a relatively more stable group of soils and are generally suited for shallow
foundation engineering purposes.
On the basis of the results obtained. it is recommended that the first 0.5 m thickness of
the black clays, calcareous clays and grey mottled clays should be mass - excavated to
allow for the partial or total compensation of projected shallow foundation structures. It
is also recommended the total excavation of the shallow yellow-brown to yellow-red
clays and the placement and construction of projected foundation structures right from
the underlying bedrock. | en |
dc.description.sponsorship | University of Nairobi | en |
dc.language.iso | en | en |
dc.title | Geological evaluation of subsurface suitability for shallow building foundations In Nairobi and the surrounding area | en |
dc.type | Thesis | en |
local.publisher | Department of Geology, University of Nairobi | en |