Building information modeling (BIM), which can efficiently manage the life cycle of structures, has been increasingly applied in the construction industry. However, it is difficult to implement BIM for existing structures, due to the differences between the design and as-built conditions. Point cloud data (PCD) can be obtained through the scan-to-BIM process, which builds a model based on the current state of the structure. The scan-to-BIM process is complicated for bridge structures and consumes significant time and resources. Therefore, this study developed a system to extract bridge design parameters automatically to reduce the time and resources for the scan-to-BIM process. The proposed automatic bridge design parameter extraction is performed in three steps: (1) noise reduction, (2) 3D transformation, and (3) parameter extraction. The validation test was conducted on the Osong test track fifth bridge in Nojang-ri, Jeondong-myeon, Yeongi-gun, Chungcheongnam-do, Korea. The system developed in this study successfully extracted the design parameters of the bridge from the PCD automatically, resulting in 0.8% error rate.

A risk management methodology that can be applicable to a shield Tunnel Boring Machine (TBM) tunneling project is proposed in this paper. A Shield TBM Risk Analysis Model (STRAM) is developed based on Bayesian networks. STRAM considers geological risk factors and TBM types, such as Earth Pressure Balance (EPB) open mode, EPB closed mode, and slurry TBMs, and systematically identifies the potential risk events that may occur during tunnel construction. It can also quantitatively evaluate the degree of risk for the identified potential risk events by estimating the cost of countermeasures against event occurrence. The proposed methodology based on STRAM can minimize the drawbacks of the TBM tunneling method, including difficulty in substituting the machine type once it is selected and excessive delay of the project due to unexpected risk events.

The present study compares and analyzes three risk analysis models that are applicable to shield tunnel boring machine (TBM) tunneling, and thus proposes an improved risk matrix model based on the causal networks applicable to sustainable tunnel projects. The advantages and disadvantages of three risk analysis models are compared, and causal networks are structured by analyzing the causal relationship between risk factors and risk events. Based on the comparison and analysis results, the causal network-based risk matrix model (CN-Matrix model), which complements the disadvantages and exploits the advantages of the three existing models, is proposed in this paper. Furthermore, this study suggests a means of modifying the weighting scores in the estimation of the risk score, which permits the CN-Matrix model to determine the risk level more reasonably. Thus, the improved CN-Matrix model is more reliable and robust compared to the three existing models.

The injection process of fracture grouting and/or fracture-permeation grouting is studied in this paper and analytical solutions are proposed to determine the fracture initiation pressure, the fracture length and thickness, and the pressure-induced filtration phenomenon for weathered granite soil, which is the most abundant soil type on the Korean peninsula. A theory is proposed and then verified through laboratory chamber tests. Experimental results show that fracture grouting occurs in unsaturated weathered granite soil, while fracture-permeation grouting occurs in saturated weathered granite soil. Also, through the experimental results with unsaturated weathered granite soil, it was found that the filtration phenomenon occurs when the water-cement ratio of the grout is less than 1.25. We were also able to demonstrate that the fracture initiation pressure as well as the fracture length and thickness obtained from the experiments match reasonably well with the theoretical values obtained from the analytical solutions.

Soil conditioning is a key factor in increasing tunnel face stability and extraction efficiency of excavated soil when excavating tunnels using an earth pressure balance (EPB) shield tunnel boring machine (TBM). Weathered granite soil, which is abundant in the Korean Peninsula (also in Japan, Hong Kong, and Singapore), has different characteristics than sand and clay; it also has particle-crushing characteristics. Conditioning agents were mixed with weathered granite soils of different individual particle-size gradations, and three characteristics (workability, permeability, and compressibility) were evaluated to find an optimal conditioning method. The lower and upper bounds of the water content that are needed for a well-functioning EPB shield TBM were also proposed. Through a trial-and-error experimental analysis, it was confirmed that soil conditioning using foam only was possible when the water content was controlled within the allowable range, that is, between the upper and lower bounds; when water content exceeded the upper bound, soil conditioning with solidification agents was needed along with foam. By taking advantage of the particle-crushing characteristics of the weathered granite soil, it was feasible to adopt the EPB shield TBM even when the soil was extremely coarse and cohesionless by conditioning with polymer slurries along with foam. Finally, the application ranges of EPB shield TBM in weathered granite soil were proposed; the newly proposed ranges are wider and expanded to coarser zones compared with those proposed so far.