Kim, J I (2016) Framework for dynamic generation and evaluation of excavation schedules for hard rock tunnels in preconstruction and construction. PhD thesis, Stanford University, USA.
Abstract
Projects with uncertain product specifications make it difficult for planners to achieve on-time completion within budget. This challenge is especially important for the excavation of hard rock tunnels because (1) hard rock tunnels include inherent uncertainties about rock mass properties (RMPs) and (2) excavation of these tunnels represents a sizable portion of such projects. Given the characteristics of hard rock tunnel projects, construction planners (CPs) for these projects frequently encounter cost overruns and schedule delays. To overcome this challenge, CPs for hard rock tunnels must be able to make informed decisions about resource-loaded excavation schedules and schedule adjustment policies (SAPs) in preconstruction and construction. These informed decisions require CPs to (1) take into account multiple sets of RMPs, (2) generate a cost-optimal schedule for every set of RMPs, and (3) evaluate expected total excavation costs (TECs) of schedules for multiple sets of RMPs, under given SAPs. However, currently CPs have difficulty making informed decisions about schedules and SAPs because they lack formal representations of estimation rationales and methods for schedule generation and evaluation required to support informed decisions. Thus, in preconstruction and construction, CPs cannot generate multiple cost-optimal schedules for multiple sets of RMPs in a timely fashion and they cannot evaluate the expected TECs of excavation schedules under given SAPs in a timely and consistent manner. In addition, existing ontologies cannot sufficiently account for multiple reference and non-reference sets of RMPs, transition costs and durations among construction methods at the method level of detail, times required for decision-making, and SAPs. Moreover, the existing methods cannot use those representations to generate cost-optimal schedules and evaluate the TECs of the schedules. To address those limitations, I developed a dynamic excavation schedule generation and evaluation framework (DESGEF) for hard rock tunnels. The DESGEF consists of (1) an ontology to represent estimation rationales of TECs for schedules and SAPs and (2) a methodology to generate cost-optimal schedules for multiple sets of RMPs and evaluate expected TECs for excavation schedules under given SAPs. To develop the ontology, I extended the existing construction method models. To develop the methodology, I specialized the existing dynamic programming and earthwork risk analysis methods for the excavation of hard rock tunnels. I validated the completeness of the ontology by interviewing 5 experts in tunnel construction projects. The validation results demonstrate that the ontology represents estimation rationales more completely than the current practice and existing approaches. In addition, to validate the speed, closeness to cost-optimality, and consistency of the methodology, I conducted Charrette tests with 12 test subjects. The validation results demonstrate that, in preconstruction and construction, the test subjects with the methodology (1) generate closer-to-cost-optimal schedules more rapidly, and (2) evaluate TECs of schedules and SAPs more rapidly and consistently than the subjects without the methodology.
| Item Type: | Thesis (Doctoral) |
|---|---|
| Thesis advisor: | Fischer, M A; Kam, C K H and Kiremidjian, A S |
| Uncontrolled Keywords: | duration; construction project; specifications; tunnel; construction method; excavation; programming; risk analysis; risk analysis; interview |
| Index terms: | cost overrun, estimation, tunnel construction, schedule delay, duration, dynamic programming, planner, ontology, construction method, interview, earthwork, specification, tunnel, level of detail, evaluation, risk analysis, construction project, decision-making, methodology, validation, excavation, charrette, programming, construction planner |
| Subjects: | technical documentation, data analysis and analytics, financial and cost management, data collection methods, profession, project controls, decision analysis, infrastructure and transport systems, education and knowledge transfer, civil engineering, contractual condition, professional development, construction methods, construction operations, programming, practitioner, building construction, environmental hazards, algorithms, research methods, production management, design process |
| Topics: | Roles and Professions, Information Management, Research Practice, Cost Management, Site Management, Contract Administration, Time Control, Digital Applications, Design Practice, Sustainability, Risk Management, Engineering Principles, Project Management |
| Descriptive scope: | 5 PCTEA |
N.B. Descriptive scope is a count of how many of the five facets of empirical research are indicated by the words used in title, abstract and keywords. It is not intended as a judgement on the research; merely a count of the kind of word we would expect to indicate Phenomenon, Concepts, Theoretical framing, Empirical techniques, Analytical techniques. If all five are present, then a code of “5 PCTEA” will indicate this. If you feel the coding for this record is questionable, we welcome discussion around the terms we matched or the way we categorized them. The facet you would expect may not be coded, or a facet may be coded inappropriately. This can also bear on a larger question, of which facets should be treated as defining in construction management research. Please get in touch, and we will look at it. More details here