Abstract
The super-speed tube transport (SSTT) system, which enables high-speed transportation in a partially vacuumed tube by minimizing the air resistance, is drawing attention as a next-generation transportation system. To evaluate the applicability of concrete as a material for the system, the effect of cracks on the airtightness of the system needs to be considered. This study aims to establish an analytical relationship between the cracks induced on a concrete tube structure and the system airtightness. An analytical model for the leakage rate through the concrete cracks is first applied to establish a differential equation, which can help determine the air flow rate into the concrete tube structure through the cracks. A mathematical formula for predicting the internal pressure changes over time in the concrete tube structure is then derived. The effect of crack development on the system airtightness is assessed through parametric analysis and a crack index for describing the extent of crack development is proposed by investigating the correlation with the system airtightness. Finally, assuming that the cracks due to external loadings are closely related to the displacement, the correlation between displacements and the airtightness of concrete tube structures is demonstrated through a set of experimental tests. As a result, the necessity of crack analysis for evaluation of the airtightness performance is emphasized.
Highlights
The super-speed tube transport (SSTT) system, which helps to minimize the air resistance of vehicles by keeping the pressure inside the tunnel or tube structure much lower than the atmospheric pressure (Figure 1), is drawing attention as a next-generation transportation system owing to its high efficiency and environmental friendliness [1,2,3,4]
This study study aims aims toestablish relationship between the cracks cracks developed on aa concrete concrete tube tube structure and the system airtightness
The crack index proposed in this study can be ensure airtightness performance, because the system airtightness was found to be highly sensitive to effectively used to provide information required to set the limit states considering the target the degree of crack development
Summary
The super-speed tube transport (SSTT) system, which helps to minimize the air resistance of vehicles by keeping the pressure inside the tunnel or tube structure much lower than the atmospheric pressure (Figure 1), is drawing attention as a next-generation transportation system owing to its high efficiency and environmental friendliness [1,2,3,4]. Developed a mathematical model for describing the air such as material permeability, thickness, and diameter of the tube structure. The current design standard applied to concrete structures considers the generation of cracks on may cause rapid inflow of outside air, which in turn can significantly affect the airtightness of the. To design tube structures to determine resulting vacuum pump capacity, air, which in turn significantly affect theand airtightness of the system. To design tube structures and to determine the resulting vacuum pump capacity, cracks To this end, a quantitative relationship between the generated cracks and the resulting inflow in the pressure inside the tube due to the air inflow through the cracks. A comparison analysis is performed to establish a crack index that shows the most correlation with the system airtightness and could describe the degree of the developed cracks at the same time
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