The pressure drop and conveying stability caused by the bend significantly affect the pneumatic conveying process of stiff shotcrete, which is the key to solving the problem of long-distance transportation. In this paper, the effects of different air velocities (32 m/s, 36 m/s, 40 m/s), water-cement ratios (0.1, 0.2, and 0.3), and bending-diameter ratios (4, 12, and 20) on the pressure drop of the elbow R1 and conveying stability R2 are studied using the response surface method. The conveying stability is characterized by the pressure variation coefficient (C.V). The response surface graph aids in the intuitive analysis of the effects of these variables. The results show that the impact of air velocity on R1 and R2 is exceptionally significant, and the interaction of each factor on the response value is analyzed. The response value and the quadratic polynomial regression equation between the various factors are obtained in addition to the flow characteristics of stiff shotcrete under different working conditions. The relationship established by the statistical processing of the experimental results can provide some reference for specifying the pressure loss model of stiff shotcrete.
Based on practice engineering and model test, and considering different bridge elevation, elevation of sea bed, and the different wave factor, the author uses the 2D numerical wave tank based on the software ANSYS FLUENT which is established by ourselves to carry on the numerical simulation to various models, and compares with the corresponding experimental values. The author verified that all the forces are descending with the increase of bridge elevation. The most dangerous bridge elevation under wave action exists in bridge design, so it should be avoided. The optimum elevation of the bridge deck is recommended +5.5 m, and some advices on practice design engineering are presented.
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