Steps in preparation of site for construction works involves geotechnical report, site clearing, excavation, grading and compaction. Steps for construction site preparation are discussed.
To construct excellent project, the condition of the project site including subsurface and surface condition must be investigated and assessed thoroughly.
Site assessment may involve determining the present and installation of underground services, specify suitable foundation depend on recommendation of geotechnical report, anticipate the level of ground water, grading amount needed for proper drainage to push water away from the structure, whether the site is difficult to excavate or not, frost penetration depth.
To build the framework as per the design, estimate the excavation volume accurately, and offer suitable drainage, structural elevations and layout must be carried out with substantial precision.
Stages or steps which are needed to undertake to prepare the building undertaking site are.
Geotechnical report creates communication between project site condition and design and construction recommendation. Therefore, to understand properties and condition of the soil of the project site, a geotechnical report about the soil of the site is a must.
This report often describes soil property and provides necessary recommendation. It is produced based on a series of tests on soil. Type of the framework dictates sampling approach, type of test, and number of test required.
After achieving and interpreting test results, type of foundation appropriate for the site, settlements and related recommendations, liquefaction possibilities, slope stability, groundwater level, soil bearing capacity , excavation related hazards, soil strength, soil classification, and many more information are offered in the geotechnical reports.
These invaluable data adequately define the properties of soil and its behavior in the future. If the undertaking site prone to earthquake, then necessary testing and recommendation must be included in the geotechnical report.
Fig.1: Preparing Site for construction undertaking
Fig.2: Borehole Sampling for Geotechnical Report
Clearing and excavation is part of the greater job which is carried out in preparing site for construction undertakings. As shown in Figure-3, trees and all sorts of vegetation on the site are removed at site clearing phase.
After the layout of the structure is set accurately, the excavation work begins and the soil is removed to a required depth in which the foundation of the structure is placed.
There are various types of machinery used to excavate and transport soil at project site. The selection of the type of machinery employed for excavation is based on the soil type, how long is the distance the soil need to be transported, soil site ability to carry load, and site accessibility.
For instance, blasting, drilling, and machinery like boulders, backhoe, shovels, and scooper are involved to excavate and transported blasted and drilled substances when rocks are present at the site.
Fig.3: Clearing Construction Site
Fig.4: Removing Excessive Soil and other Materials from Construction site
Fig.5: Construction Site Excavation
Grading at constructed site is very crucial to force water away from the structure. International construction Code (IBC 2009), provides necessary recommendation to create proper grading.
The Code states that grade slope should be at least one unit vertical to twenty units horizontal in other words 5% at a distance of 3m measured perpendicular from the wall face.
If a horizontal distance of 3 m is not available due to physical hinders, then other options need to be employed such as swales and impervious surface for which least slope must be 2% if is located within the limit of 3m. The IBC code permit minimum slope of one unit horizontal to forty-eight-unit vertical under certain conditions.
If the construction site is not flat, then suitable cutting and filling need to be carried out and the both cut and fill volume is dictated by the lowest level placement of the structure.
Final settlement of soil must be considered while grading is carried out.
Soil beneath foundation at site construction must be compacted to the required degree which as per IBC Code is 90% of maximum dry density. Compaction of soil layers which support loads is a must because it decreases settlement and hence prevents undesired incidents.
Tamping, rolling, and vibration are types of loads employed to compact soil layers. there are several machines used for compaction at construction site such as smooth wheel roller, sheep foot roller, rubber tire, crawler, and tamping plate compactor.
Not only does the compaction of soil improve shear strength but also it declines soil permeability and compressibility.
Fig.6: Bad Compaction and Poor Grading led to Cracks in the Building
Fig.7: Standard Proctor Test for Soil Compaction
Optimum moisture content should be offered to get target degree of compaction. In this regard, silt and clay are considerably sensitive because improper moisture content lead to fail the process and poor compaction will be achieved which usually is not desirable.
The optimum moisture content and compaction percentage are determined by either standard modified or proctor modified compaction test in laboratory.
approach of Dewatering Excavations at construction Site
protection procedure at construction Site – protection Precautions and PPEs
Safety Measures to Prevent Accidents at Building building Site