Site Investigation is the gathering of the information about the proposed location of a project, e.g.
The Stages of Site Investigation In general, a site investigation program should comprise four stages, i.e. Desk study and site reconnaissance The desk study is the first stage of the site investigation process which involves researching the site to gain as much information as possible, both geological and historical. The reconnaissance phase of a site investigation This site investigation is done through a site visit or walk-over survey.
Preliminary Investigation Preliminary Investigation is aimed at predicting the geological structures, soil profiles and the position of ground water table by geophysical method or by making a few boreholes. Detailed Investigation At this stage, the extent of the test, number and depth of boreholes, selection of appropriate equipment for field testing and the choice of laboratory testing are made. Monitoring Monitoring during construction and maintenance period is required whether the expectations of the proceeding investigation have been realize. Percussion Drilling Percussion Drilling is the process of making boreholes by striking the soil then removing it. Rotary Drilling Rotary Drilling uses rotation of the drill bit with the simultaneous application of pressure to advance the hole.
The sampling procedures varies according to the type of strata in which the investigation takes place.
A sampling program should be consistent with the required accuracy of design and the scale of the structures.
If a test pit is available in clay soil, an undisturbed sample may be obtained by simply carving a sample very carefully out of the side of the test pit. Several types of piston samplers are available, for instance the fixed piston sample, free piston sampler, and restraint sampler. Immediately after the tube containing the sample is brought to the ground surface, the ends of the tube should be sealed with paraffin wax. Care should be taken during shipment and stored of the sealed tube for testing in the laboratory because these processes may result in serious sample disturbance. IN SITU TESTING In some cases the data obtained from sampling and laboratory testing is less reliable than those from in- situ testing. STANDARD PENETRATION TEST (SPT) The standard penetration test (SPT) is a dynamic test and is a measure of the density of the soil. Many of the correlations developed based on hammer that have an efficiency of 60%, the results of other hammer should be corrected to this efficiency factor. The SPT data may also be influenced by overburden pressure, thus the N value should be corrected to a standard effective overburden pressure ( o ).


The site investigation is aimed at providing sufficient reliable subsurface information for most economical, satisfactorily safe foundation for the proposed structure. A good starting point is to use Ordinance survey maps which allow the selection of the site by obtaining accurate grid reference through the maps. Geological map Geological maps are probably most important source of information as these give and excellent indication of the sort of ground conditions like to be encountered.
Important evidences to look for are site lay out, surface condition, climate and hazards water levels, etc. The investigation should give information on the existence on ground structures that may need closer examination: for example, 1.
No one can ensure that the soil parameters used for design is the most representative of the soil conditions at the site unless the response is observed.
The tools are repeatedly dropped down the borehole while suspended by wire from the power winch.
Undisturbed samples are normally needed for clays at every 1.5 m depth or change of stratum.
Disturbed sample can be obtained from auger boring, core boring, split spoon sampler in standard penetration test (pit and trench, and some types of sampler such as thick walled sampler, displacement sampler, and Beggemann sampler. The term undisturbed is considered relative because the process of extracting the sample from a depth in soil, transporting the samples to laboratory and preparing the specimen for testing my introduce disturbance that can cause the result of laboratory testing will not be representative of in-situ condition.
On arrival at the laboratory, it is important to check the conditions of the samples and compare them with the states recorded in the field. The SPT is carried out in a borehole by lowering the split spoon sampler of about 650 mm length, 50 mm external diameter, and 35 mm internal diameter (Figure 2.5), and driving it using repeated blows by a freely dropped hammer at falling height of 765 mm. Generally the desk study and reconnaissance is aimed at the feasibility study of the being planned. Field observation can help for early diagnosis and redemption of any problem that might be encountered during construction. A bore hole is used to determine the nature of the ground in a qualitative manner and then recover disturbed and undisturbed samples for quantitative examination. Jetting action is accomplished by pumping water downward through the drilling bit to soften the soil. If undisturbed sample cannot be retrieved at a specific depth, then bulk samples should be taken. Undisturbed sample are generally required during a detail subsurface exploration to provide specimens for laboratory testing. A more common method of obtaining an undisturbed sample is to push a thin tube into the soil, thereby trapping the undisturbed sample inside the tube and then to remove the tube and the intact sample.


To ensure the quality of the sample, some step should be taken after obtaining the undisturbed sample appropriate tube.
The samples should be stored in a room where the temperature and humidity are kept constant and similar to the in situ-conditions.
The blow count (N) may be corrected by field conditions such as, a) energy used for driving the rod into the soil (E m ), b) Variations in the test apparatus (C s and C R ), c) Size of drilling hole (C B ) The values of E m, C s, C R, and C B depend on the SPT equipment.
The site investigation should reveal sufficient subsurface information for the design and construction of a stable foundation safe from both collapse and detrimental movements.
Aerial photography Aerial photography is another extremely useful source of information on topography and ground conditions. If the desk study shows that the site is feasible for the structure, then preliminary investigation should follows. Among the measurement made during the monitoring stage are the settlement, displacement, deformation, inclination, and pore water pressure. The removed soil can be used for field classification and laboratory testing, but it must not be considered as an undisturbed soil sample. Sample obtained from drilling by this method is relatively less disturbed as compared to samples obtained by the preceding methods. The most popular tube is the open drive sampler while the recommended sampler for the soft soil is the piston sampler.
Common types of field testing include the standard penetration test (SPT), cone penetration test (CPT), vane shear test (VST), pressure meter test (PMT), and dilatometer test (DMT). Bulk samples to be taken every 1 m or every change of stratum while alternate disturbed and undisturbed samples should be taken for silt layer at 0.75 m intervals.
Records of previous investigation Records of previous investigation reports also helpful in a desk study. Fractures and river crossings or alluvial areas that may have buried soft material or pet, their liability to cause subsidence, surface movements or instability 4.
Undisturbed samples This sample are usually needed for determining the engineering properties such as shear strength and consolidation characteristic of the soil.
The many sources of site investigation data include previous company and Public Works Departement. Information on suitability of soil for fills work, ground water condition and the possibility of flooding should be provided at this stage.



Free email marketing newsletter
Free email hotmail sign up
Free web page examples




Comments to «Site investigation presentation example»

  1. YAPONCHIK_VOR writes:
    That need to not patronise their readers.
  2. 10_ON_010 writes:
    Faster than traveling the planet the correct guy drop a man's.
  3. ElektrA_RaFo writes:
    Who are confident in their own character and that my man.
  4. Vuqar writes:
    You site investigation presentation example do not know no matter whether he likes you back whether you're single, in a connection or married.