CONSTRUCTION TECHNOLOGY (KA10802)

CHAPTER 2: SITE ANALYSIS AND SET-UP

FUNCTION OF SITE ANALYSISBefore starting construction Determine economical feasibility of chosen site.

If the soil profile of an area is not complete Risk to the construction process (Delays, Additional costs for weak soil encountered on site)

Inadequate soil investigation = Inappropriate foundation design Cause structural problems in the future (e.g. Differential settlement)

FUNCTION OF SITE ANALYSISBrownfield sites: Land that has been previously built on and used.

Necessary to seal, stabilize or remove any contaminated ground, toxic waste or other dangerous substances before building on brownfield sites.

The main function of Site Analysis: To identify and reduce risks associated with construction, by recording site features and soil characteristics, to determine the design and cost of suitable foundation and structure.

BENEFITS OF SITE ANALYSISBenefit of Site Analysis to a building team:Owner can assess project viability Consult with professional advisers.Owner, architect, structural engineer and contractor Choose best location for buildingGeotechnical engineers Design suitable foundation system

BENEFITS OF SITE ANALYSISBenefit of Site Analysis to a building team:Mechanical and Electrical (M&E) engineers Design service provisionDesign team and contractor Ensure safe construction methods are used Environmental consultants/ engineers Choose suitable methods to deal with contaminants, problem materials on site

1ST STAGE: DESK-TOP STUDYInvolves collecting all documents and materials related to the proposed site - from local and national authorities, museums, private companies and research groups.

For brownfield sites, the previous owner may have the required documents to hand.

1ST STAGE: DESK-TOP STUDYCompletion of desk-top study & relevant SI info is obtained:May avoid unnecessary, expensive ground exploration and soil tests

May avoid health and safety issues before physical investigations are carried out, location of services must be known (e.g. water, wastewater, communication lines)

1ST STAGE: DESK-TOP STUDYInformation required for a desk-top study:

1ST STAGE: DESK-TOP STUDYOwnership and legal boundaries:Owner: Provide the design team and contractor (via a legal representative) the info regarding the exact location of the site boundaries.

These need to be checked against a measured land survey conducted by JUPEM (Jabatan Ukur dan Pemetaan Malaysia).

1ST STAGE: DESK-TOP STUDYOwnership and legal boundaries:Other legal issues that need to be determined by the owners legal representative:

1ST STAGE: DESK-TOP STUDYGround conditions:

InformationLocal Authority/ Relevant CompaniesSoil and subsoil conditions JKR (Jabatan Kerja Raya)JMG (Jabatan Mineral dan Geosains) Kumpulan IKRAM Sdn. Bhd.Geological and Hydrogeological MapJMG (Jabatan Mineral dan Geosains) Hydrology and Geology Research Group, FSSAMaps and Aerial PhotographyJUPEM (Jabatan Ukur dan Pemetaan Malaysia)Meteorological InformationJMM (Jabatan Metereologi Malaysia)

1ST STAGE: DESK-TOP STUDYServices:All suppliers of services should be contacted to confirm the positions of service pipes/ cables.This includes mains water, sewage and surface drainage pipes, electricity, broadband and telephone cables.

A representative from the service company will identify their equipment on site (if service lines are in a different location than shown in plan).

1ST STAGE: DESK-TOP STUDYContaminated land/ Methane:Associated with brownfield sites local authorities may help, i.e. Jabatan Alam Sekitar (JAS)

But if needed, extensive soil tests can be conducted to confirm any contamination on site.

Methane Usually found in landfill sites, and local knowledge of old landfill is useful (Contact Local SWM company/ Municipal Council)

1ST STAGE: DESK-TOP STUDYFlooding:High frequency of flooding Potential/ Risk of damage to property and possessions.Factors include Heavy rainfallBuildings sited on/ near flood plains Poor maintenance of rivers, watercourses, surface water drainageChecks should be made about previous flooding of the site (if any), and the proximity to flood plains.

2ND STAGE: SITE RECONNAISANCEBefore entering the site: Written approvals must be obtained from the ownerThorough risk assessment exercise must be carried out.

On brownfield sites, the site may contain buildings that are structurally unsound (but still in use despite the dangers/ risks).Type of information collected during site recon:

2ND STAGE: SITE RECONNAISANCESite Reconnaisance = Visual Inspection/ WalkoverShould be conducted by 2 or more people, i.e. Architect, Engineer and ContractorObservation is made on: Subsoil, Vegetation, Marshy ground/ tanah paya (if any), Signs of groundwater and flooding, Irregular topography, andGround erosion near soft, alluvial soil.

2ND STAGE: SITE RECONNAISANCEA record should be made on existing structure as well, e.g. foundation of old building, cracks and signs of movement from adjacent buildings.

On contaminated lands, SR should be done after identifying all hazards and all safety procedures are followed.

In preparation of an SR, all maps/records should be assembled to compare with the findings on site during walk-over.

2ND STAGE: SITE RECONNAISANCEWhen conducting a walkover survey, the British Standard for site investigations (BS 5930:1999) suggests that the surveyor should: Traverse the whole area on foot Establish the proposed location of work on plans Identify and record any differences on the plans and maps Record details of existing services, trees, structures, buildings and obstruction(The remaining suggestions are found in page 21!)

2ND STAGE: SITE RECONNAISANCEDuring a site reconnaissance the following ground information and features should be noted (BS 5930:1999): Record surface features on site and on adjacent land, note the following: Type and variability of surface conditions Compare land and topography with previous records; check for fill, erosions and cuttings. Low-lying flat areas in hill country may be the site of a previous lake and can indicate the presence of soft silts and peat

2ND STAGE: SITE RECONNAISANCE Record details of ground conditions in quarries and cuttings. Record groundwater levels, and identify the position of wells and springs. Note the nature of vegetation in relation to soil type and wetness of soil. Unusual green patches in soil indicate wet ground conditions. Investigate structures in the vicinity of areas having a settlement history.

2ND STAGE: SITE RECONNAISANCEIdentification and physical location of services

Handheld sonic and magnetic detecting devices to help locate the position of services.Exact position and depth are established by digging trial pits to expose pipes, cables, etc.

2ND STAGE: SITE RECONNAISANCETo develop the site to its full potential, we:

Re-route the service lines (with permission from the authority), but this is expensive

Or, we can adjust the proposed position of the building to ensure that no disruption to major service routes occurs.

2ND STAGE: SITE RECONNAISANCE

2ND STAGE: SITE RECONNAISANCEMeasured SurveyLand surveyor = Conduct topographical survey to determine physical boundaries, existing features and variations in GL, saved in CAD (Computer Aided Drawing) or BIM (Building Information Modelling).

2ND STAGE: SITE RECONNAISANCECondition SurveyCarry out a full condition survey of surrounding and adjoining properties and structures - as a record of the physical condition on site.If any damage is caused by vibration during construction work (demolition, excavation, piling), this record is used as a reference for damage claims.

2ND STAGE: SITE RECONNAISANCEPhotographic and Video surveysA record of the original condition of the site and adjoining land/ property in case of any dispute or claim for damage.

3RD STAGE: GROUND/ SOIL INVESTIGATIONDetails of the subsoil should include:Soil type, consistency or strength, Soil structure, Moisture conditions and the presence of roots.From the nature of the subsoil the bearing capacity, seasonal volume changes and other possible ground movements are assumed.

3RD STAGE: GROUND/ SOIL INVESTIGATIONTo determine the nature of the subsoil below foundation level , we need to obtain soil samples.What are the common methods of obtaining samples? Trial pits Boreholes cable percussive boreholes and rotary drilled borehole Window sampling and dynamic probe testing

3RD STAGE: GROUND/ SOIL INVESTIGATIONWhen proposing work to existing buildings (e.g. adding another floor), check if the existing foundation was built as detailed on drawings, and check the subsoil below the foundation.Whichever system is adopted will depend on economy, the proposed building works and the nature of the subsoil. Trial pits or boreholes should be sufficient in number to determine the nature of the subsoil over and around the site of the building and should be at most, say 30m apart.

EXAMPLE: KARAMUNSING, KK

3RD STAGE: GROUND/ SOIL INVESTIGATIONGround movements that may cause settlement: Compression of the soil by building load Seasonal volume changes in the soil Mass movement in unstable areas e.g. made mining areas may have considerable settlement Ground made unstable by adjacent excavations or by de-watering, for example, due to an adjacent road cutting.

3RD STAGE: GROUND/ SOIL INVESTIGATIONBoreholes : Various methods used to excavate and extract disturbed and undisturbed soil samples. All samples taken from boreholes should be sealed as soon as possible to minimise any loss of moisture before testing.

3RD STAGE: GROUND/ SOIL INVESTIGATIONAuger boring rotary boring methodsHoles in ground made by hand or powered augerSize of auger holes: 75-150 mm dia.Short helical augers: Disturbed samples of soil are collected as they are brought to the surface, this method rarely used because soil cannot be examined in situ, and cannot penetrate to BH depth.

3RD STAGE: GROUND/ SOIL INVESTIGATIONAuger boring rotary boring methodsRotary drilling: BH cut into very dense gravel or bedrock. Samples or bedrocks are recovered in seamless plastic tubes, logged by an engineer, and taken for laboratory testing (Photograph 2.1).

3RD STAGE: GROUND/ SOIL INVESTIGATIONWindow SamplerA steel tube (with different dia.) about 1 m long with a hole cut into the wall of the tube (can view the disturbed sample in it).The tube is driven into the ground using a lightweight percussion hammer and extracted using jacks. Large tubes are driven first and removed, then smaller tubes to be inserted, driven in further.

3RD STAGE: GROUND/ SOIL INVESTIGATIONWindow SamplerSamples can be obtained to a depth of 8 m.Window sampler is done using handheld pneumatic samplers/tracked percussive samplers (Photo 2.2). Samples are shown in (Photo 2.3).Suitable to be used in sites with restricted access, i.e. minimal disturbance and for contamination investigation.

3RD STAGE: GROUND/ SOIL INVESTIGATIONWindow SamplerPercussive samplers are also used for penetrometer testingPenetrometer test: Continuous soil test procedure to determine relative density or strength of the soil.

3RD STAGE: GROUND/ SOIL INVESTIGATIONPercussion boringBH are made using light percussion equipment. The 150200 mm dia. weighted hollow tube is dropped into the hole so that the soil is lodged inside the tube (then sample is removed) In clay soils the method relies on the cohesive properties of the soil to hold it in the tube (clay cutter). In granular soils a hollow tube with a flap over its base is used (shell or bailer).

3RD STAGE: GROUND/ SOIL INVESTIGATIONPercussion boring (cont.)1 day drilling: Excavate 715 mSample obtained is classified as disturbed sampleBut in cohesive soils a 100 mm dia. tube can be used to collect undisturbed sample at bottom of the hole (undisturbed samples= for cohesive soils). Standard penetration tests (SPTs) and vane tests can be carried out in the borehole as the drilling and excavation process proceeds.

3RD STAGE: GROUND/ SOIL INVESTIGATIONPhotographic evidence from boreholesFor very stiff clays and fissured rock, take photographs of the strata using a remote-controlled borehole camera. If the BH has entered a void, use the photo as evidence to determine the nature of the void, e.g. mine shaft, sewer, cave, etc.

3RD STAGE: GROUND/ SOIL INVESTIGATIONDepth and location of exploratory investigationThe information from boreholes and trial pits are used to design suitable foundation systems.BH must penetrate through all unsuitable deposits e.g. unconsolidated fill, organic silts and very soft compressible clay.For low-rise and high-rise buildings, the depth of the borehole can be calculated using the following formulae (BRE, 1995).

3RD STAGE: GROUND/ SOIL INVESTIGATIONGround and soil tests- On-site/ In-situ test Plate load test Vane shear test California bearing ratio (CBR) test Dry density/moisture relationship SPT Cone penetration tests (CPT)

PLATE LOAD TEST

VARIOUS SOIL TESTS

CBR TEST

3RD STAGE: GROUND/ SOIL INVESTIGATIONGround and soil tests- Laboratory work Triaxial compression tests Liquid and plastic limit tests/ Atterberg limits Sieve analysis particle size and distribution Moisture content pH value tests

SIEVE ANALYSIS TEST

HYDROMETER TEST

TRIAXIAL TEST

ATTERBERG LIMITS TEST(CASAGRANDE CUP & PLASTIC LIMIT)

LIQUID LIMIT TEST: FALL CONE

PERFORMANCE APPRAISALWhen the info has been collected from the desk-top study, the site recon and the ground and soil investigations, it must be brought together in a final report, the performance appraisal.Structure of the report: The main headings should address the following.Feasibility studyEnvironmental auditRisk assessment

PERFORMANCE APPRAISALConclusions and recommendationsClear and concise conclusions based on the information gathered need to be made and any areas requiring further detail/research clearly stated.

3 Interrelated Research Activities, namely the Desk-top study, Site Reconnaissance and Ground and Soil InvestigationsSI May involve laboratory tests on liquids and gases in soil samples*3rd point: Desk-top study might reveal that there were recent site and soil investigation was carried out and the info is availableb*Desk-top study might reveal that there were recent site and soil investigation was carried out and the info is available

*Ownership and legal boundaries: Owner should provide the design team and contractor (via a legal representative) the info regarding the EXACT LOCATION of the site boundaries, and the responsibilities maintaining them. These need to be checked against a measured land survey conducted by JUPEM (Jabatan Ukur dan Pemetaan Malaysia). Any uncertainties need to be checked by the legal rep, which includes*Ownership and legal boundaries: *Ownership and legal boundaries: *Ownership and legal boundaries: Owner should provide the design team and contractor (via a legal representative) the info regarding the EXACT LOCATION of the site boundaries, and the responsibilities maintaining them. These need to be checked against a measured land survey conducted by JUPEM (Jabatan Ukur dan Pemetaan Malaysia). Any uncertainties need to be checked by the legal rep, which includes*Ownership and legal boundaries: Owner should provide the design team and contractor (via a legal representative) the info regarding the EXACT LOCATION of the site boundaries, and the responsibilities maintaining them. These need to be checked against a measured land survey conducted by JUPEM (Jabatan Ukur dan Pemetaan Malaysia). Any uncertainties need to be checked by the legal rep, which includes*******************************************