Huang Hong-wei

Risk Assessment of Voids behind the Lining of Mountain Tunnels

Accidents caused by lining damage are commonly faced problems of tunnels. These accidents may have detrimental effects on drivers and cars in the form of injury, disability, etc. One of the main causes of lining damage is void behind the lining. This study proposes a risk evaluation methodology for assessment and management of risk associated with void behind lining. In the proposed methodology, risk assessment requires the determination of probabilities and possible consequences. In order to define probability, a statistical method is used; and to define consequence, a finite element analysis is carried out; finally, the proposed method is illustrated with an example and it is found to be useful to evaluate and manage such risks.

The performance test of U-shape antenna applied in tunnel detection

Owing to the growth of population, thus increased land scarcity for normal surface road construct and improper city council planning it inflict more tunnel and underground structure constructed. As most of the constructed underground structures are subjected to severe adverse condition which need thorough inspection. To maintain the good inhabitable tunnel structure ground penetrating radar (GPR) always use as a measuring tools. GPR as an inspection tools in tunnel has been plague with series of setback. In this case a new type of antenna has been introduced in order to improve the performance in tunnel inspection. An emphasize part of the antenna design must be ensuring the directivity, bandwidth characteristic, radiation efficiency and the penetration depth. This research has been divided into three cases and those cases were performed in order to signify the characteristic of the antenna. Laboratory test and numerical simulation were carried out for the comparison and urged to the optimize solution. In this paper, Agilent E5060A ENA has been used for the laboratory test to examine the performance of the antenna. The FDTD method for numerical simulation is to prove the authenticity of the result of laboratory test. The test result illustrates that; the new designed antenna is suitable for tunnel inspection. The important improvement should be further carried out. Further studies must investigate the application of this type of antenna for the inspection of tunnel lining.

Development of radar antennas for the detection of voids behind tunnel liner and laboratory experiments

Ground penetrating radar antennas used for voids detection in the tunnel are almost ground-coupled, which leads to a slow detection speed, and also was greatly affected by the surrounding environment and operation factors, to improve the detection speed and reduce the effect of surrounding environment, the air-coupled antenna, Vivaldi antenna I was chosen, and a series improvement were proposed, finally two kinds of novel Vivaldi antennas were introduced, namely, Vivaldi antenna II and Vivaldi antenna III, the performance of the antennas was investigated numerically, and to test the performance of the antennas, some model detection experiments are carried out, and the detections results of Vivaldi antennas also was compared with the results of commercial antennas, the results indicate that the novel Vivaldi antennas are as good as commercial antenna, and Vivaldi antenna II and III has a better performance than Vivaldi antenna I, and Vivaldi antennas are air-coupled, the detection results will be better if there is a certain distance between the antenna and the tunnel lining, which provides feasibility for fast detection of tunnel disease.

MODELING OF RISK ACCEPTANCE CRITERIA FOR TUNNEL AND UNDERGROUND ENGINEERING

The importance of risk acceptance criteria research and the calculation principle for determining them are analyzed in according with the present state of art. And some fundamental risk acceptance criteria, such as the individual risk (IR), societal risk (SR), economical risk and environmental risk, are comprehensively introduced. The paper furthermore addresses and discusses some key points, future application and development of these criteria for tunnel and underground engineering. Finally a number of problems are highlighted and the needs for further research are stressed.