--- title: "Phases of EGS and its tasks" subject: "Engineering Geology II" chapter: 1 key: "semester_4/engineering_geology_ii:egs-phases-tasks" source: https://www.bctengineer.com/q/semester_4/engineering_geology_ii/egs-phases-tasks site: BCT Engineering --- # Phases of EGS and its tasks Engineering Geology II · Chapter 1: Introduction to Engineering Geology - Asked in: 2081 Chaitra, 2 marks; 2079 Asoj, 1+1 marks; 2077 Chaitra, 2 marks; 2078 Baisakh, 3 marks; 2073 Magh, 3 marks; 2072 Asoj, 3 marks; 2071 Magh, 2 marks; 2078 Poush (asked 8 times) - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_4/engineering_geology_ii/egs-phases-tasks - Whole chapter: https://www.bctengineer.com/md/semester_4/engineering_geology_ii/chapter-1 ## Question What are the phases of an Engineering Geological System (EGS)? Point out the major engineering geological tasks in each phase, especially the detailed design phase. ## Short answer EGS phases: reconnaissance (desk study, fatal flaws), feasibility (mapping, trial pits, boreholes), detailed design (detailed mapping, drilling, in-situ/lab tests, rock classification, design of foundation, slopes, grouting), construction (mapping, revising support), operation (monitoring). Detailed design: confirm foundation conditions, define parameters, delineate weak zones, design excavation, support, drainage, and locate materials. ## Answer The engineering geological study (system) of a project is carried out in successive phases, each more detailed than the previous one, so that geological uncertainty and risk fall as the design develops. | Phase | Main engineering geological tasks | |---|---| | 1. Reconnaissance / pre-feasibility | Desk study, air-photo interpretation, quick walk-over survey, identify fatal geological flaws and alternative sites | | 2. Feasibility / preliminary | Engineering geological mapping of the alternative sites (1:5,000-1:25,000), trial pits, a few boreholes, geophysical profiles, rough assessment of rock quality, construction material and hazards; compare alternatives | | 3. Detailed design | Detailed large-scale mapping of the chosen site, closely spaced core drilling, test adits/trenches, in-situ tests (permeability, plate load, shear, Lugeon), laboratory tests, rock mass classification, geological cross-sections and longitudinal sections, design of foundation treatment, slope support and grouting, quantity of borrow materials | | 4. Construction | Geological documentation of excavations (face mapping), checking design assumptions, revising support, treating unforeseen conditions such as faults or water inflow | | 5. Operation / monitoring | Monitoring of slopes, seepage, settlement and instrumentation; maintenance and hazard review | **Detailed design phase in short:** the main tasks are to confirm the foundation and abutment conditions, define geotechnical parameters for design (strength, deformability, permeability), delineate weak zones, decide excavation slopes and support, plan grouting/drainage, and locate and quantify construction materials. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Which is the correct order of EGS phases? A. Detailed design, reconnaissance, feasibility, construction, operation B. Feasibility, reconnaissance, detailed design, operation, construction C. Reconnaissance, feasibility, detailed design, construction, operation/monitoring D. Construction, design, reconnaissance, feasibility, operation Answer: C. Studies go from reconnaissance to feasibility, detailed design, construction and then operation/monitoring, each more detailed than the last. (Key point: Phase sequence) 2. What is a main task of the reconnaissance phase? A. Closely spaced core drilling and Lugeon tests B. Face mapping of excavations C. Identifying fatal geological flaws and alternative sites by desk study and walk-over D. Grouting of the foundation Answer: C. Reconnaissance uses desk study, air photos and a quick survey to find fatal flaws and alternative sites cheaply. (Key point: Reconnaissance aim) 3. Which set of tasks belongs to the detailed design phase? A. Large-scale mapping, close core drilling, in-situ tests, and defining design parameters and treatment B. Only a walk-over survey C. Only monitoring of slopes D. Only comparing alternative sites Answer: A. Detailed design needs large-scale mapping, closely spaced drilling, in-situ and laboratory tests, rock mass classification and design of foundation treatment, support and grouting. (Key point: Detailed design tasks) 4. What is done in the construction phase? A. Desk study of old reports B. Geological documentation of excavations and checking design assumptions C. Choosing between alternative sites D. Quantifying borrow material for the first time Answer: B. Face mapping and checking of assumptions let the design be revised and unforeseen faults or water inflow treated. (Key point: Construction phase) ## Related in Engineering Geology II - [Engineering geological problems of Siwalik zone](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Asiwalik-problems) — Engineering Geology II, chapter 2, asked 4× - [EGS and its main parameters](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Aegs-parameters) — Engineering Geology II, chapter 1, asked 6× - [Geological hazards of Higher Himalaya](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Ahigher-himalaya-hazards) — Engineering Geology II, chapter 2 - [Geological documentation in tunnelling](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Atunnel-geological-documentation) — Engineering Geology II, chapter 4, asked 6× - [Geological factors for hydrogeological condition](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Ahydrogeological-condition-factors) — Engineering Geology II, chapter 3, asked 9× - [Topographical and geological maps for materials](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Amaps-construction-materials) — Engineering Geology II, chapter 7, asked 7× ## Related in other subjects - [Phases of new product design](https://www.bctengineer.com/question.md?key=semester_6%2Fmachine_design_i%3Anew-product-design-phases) — Machine Design I, chapter 3 - [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× - [Engineering geological problems in tectonic divisions](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Aengineering-geological-problems-in-tectonic) — Engineering Geology I, chapter 7, asked 2× - [Pattern lobes and 180° out-of-phase array](https://www.bctengineer.com/question.md?key=semester_6%2Fpropagation_and_antenna%3Alobes-importance-opposite-phase-array) — Propagation and Antenna, chapter 2