Soil Mechanics | Project Report

SOIL MECHANICS
[Author Name(s), First M. Last, Omit Titles and Degrees]
[Institutional Affiliation(s)]

Contents
1.0 Introduction.......................................................................................................................... 2
1.1 Objectives......................................................................................................................... 2
2.0 Site Description.................................................................................................................... 2
3.0 Ground Model....................................................................................................................... 3
4.0 Ground Behaviour................................................................................................................ 4
4.1 Analysis of soil or Soil Properties....................................................................................... 5
4.2 Summary of the soil Properties......................................................................................... 8
5.0 Proposed Structure.............................................................................................................. 8
5.1 Podium.............................................................................................................................. 8
5.2 Tower................................................................................................................................ 8
6.0 Design of the Foundation..................................................................................................... 9
6.1 Philosophy of the Design................................................................................................... 9
7.0 Proposal of Foundation Design............................................................................................. 9
7.1 Deep Pile foundation......................................................................................................... 9
Capacity of Single piles...................................................................................................... 10
7.2 Capacity of Pile Groups................................................................................................... 11
7.3 Settlement of Pile group.................................................................................................. 11
8.0 Conclusion.......................................................................................................................... 13
9.0 REFERENCES...................................................................................................................... 15
10.0 APPENDIX......................................................................................................................... 17
1.0 Introduction
Several geological factors must be considered during the project proposals regarding the building and
construction elements. This will be the best way of ensuring that the building’s long safety and life is

guaranteed through a stronger foundation base. Every county council, city or region will tend to enact an
ordinance. Such kind of the enactment requires a report on the preliminary soil which has been prepared by
a registered civil engineer (Skempton and MacDonald 1956).
According to the available building codes, there is illustration that in places where deep foundations are
used, there will be need to conduct a comprehensive geotechnical investigation. Such kind of the
geotechnical investigation will include among others analysis of the conditions of the soil, recommendations
to the capacity as well as type of the foundations, methods of the construction and finally settlements
(Forsberg et al.2017).
1.1 Objectives
The primary objective of this particular project was to come up with a smart and effective design of the
foundation for the given structure/office blocks. In the final end, there will be safe recommendations as for
the best design for the structure. This would go alongside having retaining walls which consider the location
of the site as well as subsurface conditions. The project never delves into the designs which analyses the
seismic waves but instead has focused on the gravity load effects.
2.0 Site Description
2.1 Geological Setting and topographical information
The topographical map indicates that the selected site for the study is located to the north-east of Salford
City centre, east of Salford and about 2km from the centre of Manchester city. There is centre stage property
of the site to SJ 382590, 398770 as for the case of grid reference and this is equivalent to the area coverage
of 1.3 ha. The selected site was relatively square in shape measuring approximately 180m (NW-SE) by
180m (SW-NE). Topography of the selected site was relatively gently towards south east being about
+9.5mAOD and +8.5mAOD. The geological maps available clearly indicated the presence of clay soil.
According to the interpreted information the clay formation was of Paleogene geological age. Underlying
this geological matter is superficial of silty clay (Forsberg et al.2017).

3.0 Ground Model
Regardless as to whether there will be required investigation or there will be requirement of revision on the
same would be treated as a matter of commonsense. It primarily forms the part of responsibility of engineer
of safeguarding the public from harm, injuries and damages. As a result of the proposed structures /office
block’s size, location and size, the integrity in terms of the structural performance will be very important
(Nizamani, En,& Nakayama 2019).
The investigation through the concepts of soil mechanics that utilized the use of the four cable percussion
boreholes was crucial in the investigation of the soil characteristics. There was varying depth which included
in the bore analysis of Terrace Gravels, Alluvium and Made Ground. This was prior to reaching the Clay
formation commonly refered to as Salford formation in the UK geological set up. The geological
information has been summarized as shown in the table below:
. Also, the spread footings would be rather close to the thick layer of clay after excavation which proves to
be very dangerous. The layer of clay that emerges as a result of large spread footing leads to extreme
settlement and destruction to the structure. Also, the load spread by the footings greatly affects foundations
of structures around. Therefore, considering matters to do with settlement and excessive size, spread footing
as an option was regarded to be of no use (Pender 2019).

Other than spread footing, mat footing was investigated as one of the types of foundation layouts. This
however has an instant problem in its design following the insufficient data availed on the columns. Partition
of the columns assumes three different categories over which load range is assigned as per the category.
4.0 Ground Behaviour
Ground Water There was encountered groundwater while
sinking BH105 (21.9m depth slurry) and
BH103 (9.80m depth). The maximum and
minimum depths were recorded.
Made ground There is varying thickness of made ground
underlying the site. It is basically made up of
gravels, sand and cobbles. According to the
provided drawing, the construction of the
basement will be up to -5mOD.
Alluvium It was found on restricted places. It was made
up of gravels, cobbly clays, silty clays and
sandy clays. Its excavation will be extended to
-5mOD for basement set up.
Terrace Graves It spread across the entire site being found
below alluvium and Made Ground. It was
basically made up of some silty sands and
sandy gravel.
Local Clay/ Salford Clay All the boreholes dugs indicated the presence
of the local/Salford Clay. The property varied
from being stiff to very stiff with the moisture
content being about 3% lower than the plastic

limit. The index of plasticity ranged from 32%
to 58%.
Chemistry of the soil Laboratory testing procedures were carried out
to confirm various chemical properties of the
soil. Various assumptions were made include
attack of the sulphates in the case of the
concretes.
In the cases where there will improper design or deficient information related to the design, the probable
consequences will include structural failure of the building. This kind of the negative impacts can be
extended to those structures which are adjacent to the real structure/building. Constant and costly repairs
will be required which again will escalate the project’s demand.
4.1 Analysis of soil or Soil Properties
By use of the geologic profile and the boring logs in the provided data package, the category of the
underlying soil was considered to determine the exact activity that was taking place beneath the site. The
knowledge gathered was regarded important in drawing conclusions to the type of foundation that best suit
the site. This process involves series of steps and the first was examining the geologic profile as well as the
report to acquire the primary knowledge on the composition as well as the depth of the soil beneath
(Houlsby 2016).
The composition of the soil beneath includes a slight cemented Merritt layer of sand (of thickness 30 ft.),
clay-like sands on the top layer of local area formation composting of extremely stiff to silt clays which are
hard with intermittent lenses of dense gravel. Beneath the formation of San Antonio lies Alameda formation
comprising of a pair of partitioned halves, whereby the lower half is sandy oxidized clay and the upper half
is hard marine clay (Fang 2002). The above mentioned layers lie on a bedrock of Franciscan which is not
regarded for this design. In actual fact, a fairly thin layer of sand rests upon a very thick layer of clay,
however, dense gravelly lens of sand found within the formation of San Antonio constitute a greater part for
the ultimate design.

Figure 1: showing composition of the underlying soil
There are crucial details which are necessary on perception of the general tendencies concerning the site
settings as indicated in the above soil profile. A particular soil profile was then developed with the help of
data issued on the three borings. The soil profile which was constructed indicated a match of the site to the
general trends in geologic (Fleming, Weltman and Randolph 1992). The site is observed to be of a sand
layer resting upon a thick layer of clay as given in the figure below. The presented data also indicated that
the gravelly layer of sand extended to the depth of around 40 ft. and more through the site. On understanding
the strength as well as the settings of the underlying site soil, analysis was made to explore the varied types
of foundation (Elliott et al.2017).

Figure of site layout indicating the cross-section applied in constructing specific soil profile
Figure 2: showing site specific soil profile
In the analysis whereby type of the foundation was a factor of consideration, shallow foundations were
considered first followed by deep foundations. This was done considering the lower costs incurred on
materials as well as the installations required by the shallow foundations. The shallow foundation would be
regarded as a better option compared to deep foundation if and only if it could suit column building demands
(Tomlinson 2001).