Research On The Subway Shield Construction Risk's Controllable Degrees Of Alarm Based On Extenics Theory

The current researches on risk management and the early-warning system of metro project concentrate on the recognition of risk factors and early-warning diagnostic methods. This thesis mainly focuses on analyzing early-warning diagnostic methods for limited time and ability. In the early-warning system, the trigger of preplan needs two factors: one is the occurrence probability of a risk, another is the serious consequence of a risk. As to the estimation on the risk consequences severity, the existing research focuses on the measurements to the casualties and loss of materials at the place where risk just happened. While the delayed consequences and repeatability of the risk are important indicators of the risk consequences severity, especially in metro projects, the chain effects of risk will cause great damages. If you have not considered the delayed consequences and repeatability of the risk, and have not judged controllable degrees of warning-signals, the implementation level of preplan and strength of organizational measures would be lack of evidence. So it is very necessary to research whether the risk is controllable or not and the controllable degree of risks in metro projects.This thesis attempts to introduce the concept of controllability into the subway risk management. Under the condition of fully identifying warning signs, quantifying the warning degrees and analyzing the controllable degree of warning sources, then combining the quantitative results and other diagnosed results of warning signals to start the appropriate level and strength of risk response measures (preplan). It not only solved the start level and the strength accuracy of the preplan, but also providing the decision-making basis for dealing with the multiple warning signs under limited resources situation.As to controllable degrees of warning-signal, this thesis uses the extenics theory, applies extenics set theory into alert diagnostics, and makes warning degrees and controllable degrees judgement for underground deep foundation pit in subway construction.First, combining the methods of WBS-RBS and HAZOP in the deep foundation pit to find the evaluation indexes of the warning signs in subway construction hazard, and making use of experts experience and Heinrich's accident law to define the warning limit, so that the standard subway construction disaster warning diagnosis model and the warning signs monitoring indexes matter-element model can be obtained. Then, considering the difficulty in getting data, this thesis adopts the Monte Carlo simulation method to simulate the subway construction disaster alert status matter-element model, and calculates the warning degrees and controllable degrees of each simulate status. At last, makes fitness analysis for the warning degree and controllable degree of the simulation status and proves the rationality and feasibility of the design through the expert questionnaires and interviews.Finally, this thesis illustrates the calculation process of the warning degree and the controllable degree combining with a case, and the final conclusion fully demonstrates the practicability of the design, as well as guidance for implementation of the preplan measures.In this thesis, the controllable degree of risk which is the Concept in the control theory has been introduced to the early warning system of subway construction risk. Introduced the concept of controllability to the subway construction part of disaster early warning systems of control, give a better solution to solve the problem of the subway construction process control methods and plans for decision-making. Respectively, as the goal with reducing the degree of police control and controlling to no warning, quantify the controllable degree of risk, this quantitative approach is consistent with the risk management concept. Course of the study has great theoretical and practical significance.