--- title: "Purposes of site investigation" subject: "Engineering Geology II" chapter: 4 key: "semester_4/engineering_geology_ii:site-investigation-purposes" source: https://www.bctengineer.com/q/semester_4/engineering_geology_ii/site-investigation-purposes site: BCT Engineering --- # Purposes of site investigation Engineering Geology II · Chapter 4: Engineering geology in site selection, investigation & construction/excavation - Asked in: 2079 Asoj, 1 marks; 2073 Bhadra, 2 marks; 2077 Chaitra, 3 marks; 2076 Bhadra, 2 marks; 2071 Bhadra, 2 marks; 2079 Chaitra, 1 marks; 2073 Magh, 4 marks (asked 7 times) - Video: [What is Geotechnical Investigation or Soil Investigation?](https://www.youtube.com/watch?v=ClCUdEyqm4Q) — Civil Mentors - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_4/engineering_geology_ii/site-investigation-purposes - Whole chapter: https://www.bctengineer.com/md/semester_4/engineering_geology_ii/chapter-4 ## Question What are the purposes of site investigation? (Define site investigation and explain why geological site investigations are required.) ## Short answer Site investigation is the systematic study of a site's geology, groundwater, and engineering properties to assess suitability and provide design data. Its purposes include selecting safe foundations, detecting defects, evaluating hazards, estimating material quantities, and preventing costly failures. ## Answer **Site investigation** is the systematic collection, analysis and interpretation of geological, geotechnical and hydrological data of a site, to decide its suitability and to provide the information required for the design and construction of a civil engineering project. #### Why geological site investigation is required 1. **To select a suitable site** or alignment among alternatives. 2. **To find the soil and rock types** and their sequence, thickness and extent. 3. **To determine engineering properties:** bearing capacity, shear strength, compressibility, permeability. 4. **To locate geological defects:** faults, shear zones, joints, cavities, landslides and weak layers. 5. **To determine groundwater conditions:** water table, seepage and quality. 6. **To assess hazards:** earthquake, flood, landslide, erosion and subsidence. 7. **To design foundations, slopes and support systems** economically and safely. 8. **To estimate quantity and quality of construction materials.** 9. **To choose the construction method** and equipment, and to estimate cost and time. 10. **To prevent failures,** unexpected costs, claims and delays in the contract. 11. **To assess the environmental impact** of the project on the ground. Investigation is done in stages: reconnaissance, preliminary and detailed. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. What is site investigation? A. Only the final construction of foundations B. Systematic collection and interpretation of geological, geotechnical and hydrological data of a site for suitability and design C. Only a laboratory test of concrete D. Estimating project profit Answer: B. It provides information for design and construction decisions. (Key point: Definition) 2. Which properties does site investigation determine for design? A. Colour and taste of rock B. Market price of land C. Bearing capacity, shear strength, compressibility and permeability D. Number of workers Answer: C. These ground properties are required for foundation and slope design. (Key point: Engineering properties) 3. Why must geological defects be located? A. They improve the strength of the ground B. They only affect the appearance C. They are important only after construction D. Faults, shear zones, cavities and weak layers can cause failures and unexpected costs Answer: D. Finding defects early prevents failures, claims and delays. (Key point: Locating defects) 4. In what order are the stages of investigation done? A. Reconnaissance, preliminary, detailed B. Detailed, preliminary, reconnaissance C. Preliminary, detailed, reconnaissance D. Detailed, reconnaissance, preliminary Answer: A. Investigation proceeds from broad to specific. (Key point: Stages) ## Related in Engineering Geology II - [Detail stage of EG site investigation](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Adetail-stage-investigation) — Engineering Geology II, chapter 4 - [Tunneling and site investigation process](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Atunneling-site-investigation-process) — Engineering Geology II, chapter 4 - [Geological investigation of tunnel and road](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Atunnel-road-investigation) — Engineering Geology II, chapter 4 - [Types and methods of site investigation](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Asite-investigation-methods) — Engineering Geology II, chapter 4, asked 7× - [Geology in bridge site selection](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Abridge-site-selection) — Engineering Geology II, chapter 4, asked 6× - [Direct methods of sub-surface investigation](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Adirect-subsurface-methods) — Engineering Geology II, chapter 4, asked 3× ## Related in other subjects - [Engineering geological map and site investigation](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Aengineering-geological-map-and-site) — Engineering Geology I, chapter 1, asked 3× - [Pre-feasibility site-specific investigations](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Aprefeasibility-site-investigations) — Hydropower Engineering, chapter 2 - [Methods of surface and subsurface site investigation](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Amethods-of-surface-and-subsurface) — Engineering Geology I, chapter 1, asked 4× - [Pre-feasibility vs feasibility; site investigations](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Aprefeasibility-vs-feasibility-investigations) — Hydropower Engineering, chapter 2