lecture2 site investigation
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1. A site investigation determines the suitability of a site for construction by examining physical aspects like soil composition and legal aspects like planning permissions. 2. The investigation assesses the site suitability, helps with design and construction planning, and predicts potential issues. Information is needed on soil properties, groundwater, and excavated materials. 3. The investigation process involves a desk study of existing information, a site walkover, detailed tests and sampling which may include trial pits and boreholes to examine soil and groundwater conditions.
lecture2 site investigation
- 2. PURPOSE To determine the site’s suitability for building and the nature and the extent of preliminary work that will be needed Why it is important? It will shows the detailed to many physical aspect such as subsoil composition, demolition and the legal aspect such as planning permission, right of access and preservation order 2
- 3. OBJECTIVES • To assess the general suitability of the site with the proposed works • To help produce a design which is adequate and economic • To help overcome possible difficulties & delays that may arise during construction period due to ground and other local conditions • To predict possible changes that may occur/cause of all changes in site condition • To maximize potential of the site 3
- 4. DESCRIPTION A combination process which range from looking at published information such as maps to arrange laboratory test on the soil 4
- 5. Information required from a site investigation: a. Information affecting the design of the structure: shear strength and compressibility of the soil b. Information affecting the construction of the works: the extent and properties of material to be excavated, or to be used for fill or for road bases or concrete aggregates 5
- 6. Information required from a site investigation: c. Information on ground water conditions: the level and seasonal variation of the water table, the pressures in the soil water, and the permeability of the soil. 6
- 7. Planning an investigation: • In the earlier stages of an investigation, the information available is often inadequate to allow a detailed plan to be made. • The investigation must therefore proceed in 3 stages: 1. Desk study 2. Site reconnaissance 3. Detail Examination of Tests and Programs 7
- 8. INFORMATION/ISSUES TO CHECK 1. Site Location Nearest town and city Schools, emergency services, entertainment, recreation, shops, transport and employment Distance from head office (client & builders) & traveling time Distance from nearest railway station to the site 8
- 9. INFORMATION/ISSUES TO CHECK 2. Accessibility Approach and site access roads, width, gradient, bends, sharp corners, condition and construction relative to transport heavy plant and equipment Bridges, strength, width and clearance height Temporary roads, rolled metal tracts or consider preparing sub base for new roads as temporary access 9
- 10. INFORMATION/ISSUES TO CHECK 3. Availability of space Site offices, canteen, stores and compound Material storage areas and handling Construction area and assembly areas Plant location 10
- 11. INFORMATION/ISSUES TO CHECK 4. Services Water, drainage, electricity, gas & telephone Location will be determined from maps by consultation with the appropriate local authorities An estimate of buildings usage is also for ascertaining the demand on sewers and drains 11
- 12. INFORMATION/ISSUES TO CHECK 5. Ground composition Boreholes are required to determine : Changes in strata Strength of subsoil Toxicity of subsoil Stability of excavation Water table (depth below surfaces) 12
- 13. INFORMATION/ISSUES TO CHECK 6. Site clearance and demolition A plan of the site should indicate trees, shrubs and existing buildings and a site survey will reveal the extent of necessary leveling Demolition and excavation Method and cost Effect of trees and structural prevention orders 13
- 14. INFORMATION/ISSUES TO CHECK Reuse of materials Protection of adjacent building Special insurance requirement Compensation payment and liability for damage Distance to spoil tips and charge 14
- 15. IN GENERAL… • Dealt with local planning authority to ascertain whether there are special/significant restrictions which could adversely affect the development of site building line position • Survey should include details of neighboring development, future development and the position with regard to facilities in the area • Should enquire the existence of any restrictive covenants such as right of way, light & drainage which may restrict the development 15
- 16. THE PROCESS • Desk Study • Site Reconnaissance/ Walk over survey • Preliminary report or feasibility study • Preliminary Ground Investigation - Planning of main Preliminary report • Main Ground Investigation • Laboratory testing • Financial Report (Return of Investment) • Final report 16
- 17. DESK STUDIES • It is important to collect all available information about the site before starting work. • A desk study is the collation and review of information already available about a site, and is carried out at an early stage of site appraisal to inform and guide the remainder of the site investigation. 17
- 18. DESK STUDIES • Collect as much material as possible about the site such as- Maps (geological, ordinance survey, etc) Air photograph Geological books & journal Mining records & reports of previous site investigation Library, news paper, adjacent buildings, etc. 18
- 19. DESK STUDIES 19
- 20. SITE RECOINAISSANCE / WALK OVER SURVEY The initial document search should be followed by a walk-over survey of the site and its surroundings. This should be a methodical examination of the site, based on defined classes of information, which complements the desk study and typically provides valuable information on matters such as: Topography: indications of slope instability, spoil heaps or signs of ground subsidence resulting from mining. 20
- 21. SITE RECOINAISSANCE / WALK OVER SURVEY Geology: exposures of soils and rocks which can be examined and sampled. Surface water and ground water: signs of flooding; springs; water logging Vegetation: signs of vegetation die-back or restricted vegetation as a result of contamination of the ground; presence of invasive species such as Japanese Knotweed; trees which may cause shrinkage and swelling of clay soils. 21
- 22. SITE RECOINAISSANCE / WALK OVER SURVEY The invasive root system and strong growth can damage foundations, buildings, flood defences, roads, paving, retaining walls and architectural sites. It can also reduce the capacity of channels in flood defenses to carry water 22
- 23. SITE RECOINAISSANCE / WALK OVER SURVEY Ecology: indicators of protected species, newts, badgers, bats, nesting birds. Contamination: indications of spills, disturbed ground, areas of fill or spoil heaps, old fuel or oil tanks. Structures: settlement of existing structures or the use of asbestos; indicators of archaeological value. 23
- 24. SITE RECOINAISSANCE / WALK OVER SURVEY Local Knowledge: anecdotal information on past uses of the site or past problems in the area. Access & services: information such as access for site equipment and location of buried or overhead services 24
- 25. DETAIL EXAMINATION OF TESTS AND PROGRAMS/ DETAILED EXPLORATION The principal objectives of the detailed soil test/investigation are as follows: a. To determine in detail the geological structure of the site, including the thickness, sequence and extent of the strata. b. To determine the ground water conditions 25
- 26. DETAIL EXAMINATION OF TESTS AND PROGRAMS/ DETAILED EXPLORATION c. To obtain disturbed and undisturbed samples for identification and laboratory testing d. To carry out tests to determine the mechanical properties of the soil insitu 26
- 27. DETAIL EXAMINATION OF TESTS AND PROGRAMS/ DETAILED EXPLORATION There are two principal methods of investigating the ground conditions, trial pits and boreholes 27
- 28. GROUND INVESTIGATION Trial Pits Trial pits are shallow excavations going down to a depth not greater 6m. The trial pit as such is used extensively at the surface for block sampling and detection of services prior to borehole excavation. Can be dug by hand or mechanical excavator 28
- 29. GROUND INVESTIGATION Trial Pits Only suitable in dry area as they allow hand cut samples to be taken which minimize the disturbance of sample Most suitable use in exploring back filled area and sites overlain by variable natural deposits 29
- 30. GROUND INVESTIGATION 30
- 31. GROUND INVESTIGATION Boreholes • A borehole is used to determine the nature of the ground (usually below 6m depth) in a qualitative manner • Recover undisturbed samples for quantitative examination. Where this is not possible, for in gravelly soils below the water table, in-situ testing methods are used. 31
- 32. GROUND INVESTIGATION • Obviously the information gained from a borehole is an extremely limited picture of the subsurface structure. It is therefore essential to compare the results obtained with those that could have been expected from the desk study. The greater the number of boreholes the more certain it is possible to be of the correlation and thus to trust in the results. • The two principal types of boring machine used for Site Investigation which is light percussive and drilling machines. 32
- 33. GROUND INVESTIGATION 33
- 34. TASK 1 Your team are appointed as a project leader to a proposed mix development project in Sri Iskandar, Perak. The site is located on existing 300 acre of ex-mining area. You are required to conduct the site exploration according to phase by phase. Assumption can be made to suit to your project and site. (1 hour task, 30 minutes for presentation)