The existence of giant karst cave can cause collapse and water inrush hazards during the excavation tunnel, causing serious economic losses. In this paper, based on FEA software MIDAS, a numerical simulation model for backfilling large through cross-section tunnel was established. distribution characteristics change rules displacement field, stress horizontal support stress, plastic zone surrou...

A trisonic wind tunnel has been modified to improve its flow quality when operating at transonic speeds through perforated walls and side suctions. The usefulness of such a perforated wall, already known, is reduction of the blockage effect as well as the shock elimination. Two types of perforated walls have been used in this investigation. The first wall had a porosity of about 22% and the hol...

A constant cross-section wind tunnel usually experiences a negative pressure gradient (ie, favorable gradient, FPG), resulting in certain degree of discrepancy between the simulated and idealized atmospheric boundary layer (ABL) flows. To investigate its impact, three large-eddy simulation (LES) cases were conducted this study: one simply reproduced tunnel, removed FPG by adjusting ceiling heig...

An open-jet wind tunnel operating within an anechoic chamber was developed for the purpose of the study of V/STOL noise mechanisms. An existing low-speed conventional hardwalled wind tunnel was modified to operate as an open-jet tunnel; an anechoic chamber was then constructed around the test section. The resulting aerodynamic and acoustic characteristics of the tunnel are discussed. This work ...

A rapid, precise and automated means for the regular inspection and maintenance of a large number of tunnels is needed. Based on the depth study of the tunnel monitoring method, the CNU-TS-1 mobile tunnel monitoring system (TS1) is developed and presented. It can efficiently obtain the cross-sections that are orthogonal to the tunnel in a dynamic way, and the control measurements that depend on...

Railway tunnel clearance is directly related to the safe operation of trains and upgrading of freight capacity. As more and more railway are put into operation and the operation is continuously becoming faster, the railway tunnel clearance inspection should be more precise and efficient. In view of the problems existing in traditional tunnel clearance inspection methods, such as low density, sl...