Volume 6 – Geotechnical Manual, Site Investigation and Engineering ...

Chapter 1 PLANNING AND SCOPE
1 PLANNING AND SCOPE
1.1 INTRODUCTION
One of the more important tasks to be considered, prior to carrying out soil investigations (SI) is to
first understand clearly what is intended for the project in terms of design and construction, and the
existing conditions of the site on which the project is to be established. Accordingly, where available,
the requisite information to be had at the early stages of SI planning includes the detailed collection,
inspection and study of the following:
i. Topographic Maps: assist in or complement the examination of earthworks, soft ground and
or or slope for site reconnaissance and planning of SI;
ii.
iii.
iv.
Geological Maps and Memoirs: assist with the planning of SI; methods of SI; and in deciding
the extent of field and laboratory testing required or necessary;
Site Histories: a good understanding and appreciation of the existence of old foundations,
tunnel, underground services and etc. will provide for better SI planning;
Results of Adjacent and Nearby SI: provide for a more efficient and economical SI;
v. Details of Adjacent Structures and Foundations: provide for better safety assessment and
prevention of foundation failure or settlement of adjacent properties due to current or
proposed foundation works; and
vi.
Aerial Photographs: provide indication of geomorphological features, land use, problem areas
and layout arrangements, and are particularly useful for highways and hillslope
developments.
1.2 GENERAL
By general convention, site investigation can be defined as the process by which geological,
geotechnical, and other relevant information which might affect the construction and performance of
a civil engineering project is acquired.
Due to the irregular nature of its deposition and its creation through the many processes out of a
wide variety of materials, soils and rocks are notoriously variable, and often have properties which
are undesirable from the point of view of a proposed structure. Often, the decision to develop a
particular site cannot often be made on the basis of its complete suitability from the engineering
viewpoint. Thus geotechnical problems may occur and require geotechnical parameters for their
solution.
1.3 OBJECTIVES
Referring to the definitions as specified by the various Codes of Practices (BS CP 2001:1950, 1957;
BS 5930:1981 & MS 2038:2006), the objectives of site investigation can be summarized and adopted
herein as providing data for the following.
i. Site selection. The construction of certain major projects, such as dams, is dependent on the
availability of a suitable site. Clearly, if the plan is to build on the cheapest, most readily
available land, geotechnical problems due to the high permeability of the sub-soil, or to slope
instability may make the final cost of the construction prohibitive. Since the safety of lives and
property are at stake, it is important to consider the geotechnical merits or demerits of
various sites before the site is chosen for a project of such magnitude.
March 2009 1-1