Railway ground borne vibration is a major problem for high-speed and intercity trains. This problem causes many environmental as well as financial problems for railway companies. In the past decades, there have been numerous methods and strategies to avoid the excessive vibration from vehicles. Many of these methods have been tested and used in tracks and surrounding structures while others are still theories. This paper intends to discuss the current practice in railway vibration reduction and the effectiveness of each method for the different track, vehicle and structures. The methods are divided into three groups; in track, in the path and at the destination solutions. For each category, the results from state-of-the-art research and practice have been presented and conclusion on the appropriate methods and strategies for each case has been made.
Scrutinizing the considerable flow energy in a spillway plays a significant role in maintaining downstream dam safety, and due to this fact, the dimension of the stilling basin will be enormously reduced, and from an economical point-of-view, construction costs will dramatically reduce. This phenomenon may even result in the removal of the stilling basin. A stepped spillway is one of the best structures for this purpose. In this experimental study, steps in the stepped spillway are equipped with inclined steps with various slopes, to find out how they influence their relative energy loss. Results illustrate that using inclined steps, considerably affect both the nappe and skimming flows; however, the energy loss in nappe flows is greater than that in skimming flows. Analyzing the results of experimental tests side-by-side with the results obtained from other researchers makes clear that the method used in the current investigation is more efficient than previous ones.
A spillway is one of the most important parts of a dam for controlling floods. Among different types of spillways, stepped spillways are one of the best energy dissipaters. Due to technological advances and the satisfaction of two elements for safe and low-cost construction, the use of stepped spillways has increased widely. Due to this, more studies are focused on stepped spillways. Researchers have made some efforts and proposed different methods to improve structural efficiency to dissipate energy. Modifications on step geometry, regarding flow regime type, are one of these efforts. Flow pressure and its fluctuations on the steps of the stepped spillways is one of the main factors affecting structural design and safety. In this experimental research, reverse inclined steps combined with the end sills have been applied in four degrees [0o (horizontal), 5o, 8o, and 11o] to obtain static pressure in both the nappe flow and skimming flow regimes of stepped spillways. Static pressure obtained from reverse inclined steps with end sills have been compared to the amount in the horizontal step. Results indicate a slight increase in the energy loss rate when reverse inclined steps have been applied in the nappe flow regime of stepped spillways.
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