Multi-Parameter Based Risk Evaluation And Pre-Warning System For Deep Excavation

Risk of deep excavation increases with the increase of the size and depth, and its risk evaluation and control has caused widespread concern. Currently, risk evaluation of deep excavation mainly focuses on theoretical research, and risk pre-warning and control in practice is mainly based on the single parameter control value set by the norms. According to engineering practice, this paper combines the mechanical properties, construction risk source and monitoring data, raises the multi-parameter risk evaluation method based on mechanical analysis and statistical laws and makes a quantitative pre-warning to construction. The main contents include the following respects.1,The multi-parameter risk evaluation method has been raised based on the mechanics and statistical results of the correlation of the deep foundation force and deformation indicators. On the basis of the analysis of common types of accidents of deep foundation pit, sources of risk in deep foundation construction have been identified. This paper analyzes the mechanical mechanism of the force and deformation of the deep excavation, combines mechanical correlation and its statistical relationship between various parameters of foundation construction and quantitatively determinate harmonious relations and the corresponding risks among the parameters. Then, multi-parameter risk evaluation and pre-warning method has been raised combined with identification of risk sources. The case studies show that this method can determine the excavation risks which can't be identified by the conventional single-parameter risk warning method, and reflect better the inner force and deformation of the foundation pit supporting structure and the surrounding environment, compared with single-parameter method.2,Dynamic multi-parameter risk evaluation and pre-warning method is raised, combining the multi-parameter risk evaluation method with displacement back analysis theory. Based on monitoring data, the method back analyzes and dynamic forecasts deformation of support structure with elastic foundation beam method. Then, it dynamic forecasts risks of deep excavation on next working condition and warns to control the risks.3,The dynamic multi-parameter risk evaluation software has been developed and applied in engineering, based on information technology. This software combines the multi-parameter risk evaluation mode with the finite element displacement back analysis dynamic evaluation theory for the core modules of risk calculation, which has capacity of three-dimensional solid modeling, as well as risk evaluation and early warning. The result of engineering application indicates that this software has a good function in displaying the three-dimensional excavation and space-time data and it also accomplishes the multi-parameter risk evaluation and dynamic prediction of the deep excavation, which can be used in judging and warning the risk and its source in the excavation procedure and compensates the deficiencies of routine monitoring and controlling.