In order to understand the nature of the dangers associated with the excavation, the study began with a detailed study of accident cases and previous literature. Subsequently, the current state of security management, the related security rules established by OSHA and the most advanced BIM technologies were reviewed. The initial investigation into the hazards of excavation work identified in accident cases led to the development of a conceptual framework for the modeling of automated safety excavations. Subsequently, the prototype of the system was developed and implemented in a real world case study to test the usability and effectiveness of the system.
The proposed approach, as shown in Figure 1, reflects the conceptual framework that proactively addresses the risks of landslides, falls and emergency exits. The conceptual framework for the BIM-based excavation safety compliance modeling approach consists of three parts. First, the extraction of relevant rules from the pool of construction industry best practices and regulations along with other guidelines and process information, including field tests and drawings. The second part consists of visual programming and BIM. The former is used to convert the required security rule information into graphical algorithms in a single scripting environment, while the latter is used to integrate the process into a common place. Likewise, the third part is comprised of an automated modeling tool, which executes safety rule algorithms on information captured from two-dimensional (2D) data drawings on a BIM platform.
Prototype system proposed based on the framework
Based on the methodology and framework provided above, an automated excavation safety modeling system proposed as a tool for automated compliance safety planning is developed. This system is called the Auto-Exca Safety Modeling System, which consists of the following three modules, namely, (1) Information Extraction and Logical Design (IELD) module; (2) information conversion and process integration module (ICPI); and (3) module for generating safety and automotive plans (ASPG). The functions and systematic process of the prototype system in each module are detailed in the following sections.
4.1. Information Extraction and Logical Design (IELD) module
As the name suggests, the function of this module is to extract information from the raw data. The Information Extraction and Logic Design (IELD) module begins with the review of OSHA regulations. These rules provide best practices and lessons learned in the construction industry. The IELD module focuses on extracting relevant information from the OSHA set of regulations. These deleted relevant rules are then manually converted to mathematical logic and thus machine-readable data in the next module. As shown in Figure 2, additional required guidelines such as soil type and actual size of excavation are also considered in this module, which should be included in the ground report and excavation plans respectively.
Extraction of the relevant safety rules
The cause of incidents provides vital information for safety planning; The historical data relating to the excavation was reviewed and analyzed to discover the main risks and causes. Landslides, fire exits, machinery and people falling into the trench and people hit by machinery were the main potential hazards identified during the investigation of the accident. In addition to this, other risks have also been reported such as lack of oxygen inside the trench, fires and water leaks. Among these, landslides represent the greatest potential danger for excavation workers. To limit the scope, this study considers only the first three potential hazards (collapses, fire exits and falls). The remaining risks associated with the excavation work are out of reach at this stage of the investigation. The standard prevention methods applicable to the minimization and mitigation of associated risks have been thoroughly investigated in the context of regulations (OSHA).