The effect on residential life for the tunnel construction
With the appearance of tunnels in the city or downtown, residential life and building is influenced inevitably by drilling and blasting construction at the entrance of tunnel. In order to reduce the effect, the monitoring of effect on resident, such as dust and noise was conducted during the construction of the entrance of tunnel. The monitoring result shows: (1) Dust content is 20 mg/m3 at the entrance of tunnel for blasting. It is 60 mg/m3 during the construction of wet pneumatically placed concrete. It is higher than the standard of health, 5.3 mg/m3. (2) Noise is 85 decibels when ventilation and noise is 200 decibels during the construction of drilling that is more than the standard, 60 decibels. It provides the reference for similar engineering.(3)The surface settlement induced by drilling and blasting in tunnels affects residential life.
UDEC modeling of a field explosion test
A field explosion test is conducted to investigate the blast wave characteristics and propagation in jointed rock mass. A hybrid AUTODYN and UDEC scheme is used to predict the rock mass response due to the explosion. The original prediction is then modified by involving the actual test conditions and dynamic equation of state of the rock material. Correlating the prediction results with the field explosion test results shows that the hybrid AUTODYN and UDEC scheme is capable of modeling explosion problems with high reliability. It is observed that the modified prediction result agrees better with the field test result than the original prediction result, which implies that involving dynamic parameters in the modeling is very important to produce reliable prediction results.
Accurate measurements of output characteristics and detonations of motorbike high-speed racing engine and their optimization at actual atmospheric conditions and combusted mixture composition
Abstract At a motorbike high speed racing engine there is very important an output engine characteristics which depends significantly on a detonation combustion rate, atmospheric conditions and a combusted mixture composition. The combustion process has got a relevant influence on a wear degree of main engine parts or on their damage eventually. The detonation combustion rate is very important because this kind of burning can be not only destructive but a useful phenomenon, as well. If the process of detonation burning is kept on a certain level, it can help significantly to the next increasing of an engine power output. In this article there is described the measurements of output characteristics of a high-speed racing engine which were performed by means of a data-recording system and the detonation combustion was evaluated using a quantitative method. The actual values of atmospheric conditions and the mixture composition were added to the measured values. Then the obtained values are compared visually with a damage degree of an engine piston caused by the detonation burning. The result is a limit value expressed in a number of detonation units related to a run distance interval of the vehicle driven by the high-speed racing engine. In framework of this run distance interval there is the process of detonation burning profitable. As well as it increases an engine power output and together it is not destructive with regard to engine design parts.