| Dynamic compaction method, which used to improve the bearing capacity of soft ground by raising hammer to a certain height and then it free fall, compactes the foundation so that it can be rapidly consolidated.It is increasingly widely used in various types and different purpose of foundation treatment engineering in world wide, for its outstanding characteristic, such as economic benefit, remarkable effect, convenient construction, short construction period and so on.At present, to realize the the separation and integration of the hammer and lifting mechanism, self-release mechanism are widely used in the construction of dynamic compaction. But the work efficiency isn’t high because of decoupling, hooks and other complex processes, at the same time manual strength, and poor construction safety are also the typical problems.Therefore, continuous dynamic compaction technology becomes an urgent need.Continuous dynamic compaction is also called dynamic compaction which is not decoupled. The hammer is promoted to the specified height, and then release the clutch or brake, so that the hammer can fell at the speed close to freefell until it touches the ground.During the process, hoisting rope and drum are drived by the hammer. To ensure the efficiency of construction, it should brake the drum and rope as soon as the hammer fell on the ground to reduce the length of the wire rope in brake. Meanwhile, premature brake will result in overloading of institutions and whole even cause an accident.Obviously, it is unable to guarantee the best braking effect rely on the judgment of operators, thus automatic control technology must be adopted.So fer, and however, there are no related theoretical and experimental studies to be reference for the continuous dynamic compaction technology.lt brings challenges for the automatic control technology of continuous dynamic compaction.Based on the analysis of the structure of free fell brake and its brake mechanism, using dynamic simulation and experimental research method by dynamics analysis of free fell hammer and winch brake, this paper obtains the length of wire rope in brake of winch under different working temperatures, and gives the optimized braking time to be the theory basis for continuous dynamic compaction automatic control.The heat of free fell brake is particularly serious due to the high operating frequency of dynamic compaction continuously work, its strength and fast brake. This kind of phenomenon can shorten the life of the brake; in serious cases it can result in significant security risks. This paper builds the fluid-so lid coupling simulation model of clutch using CFD software Fluent combined with3D design software Pro/E to analysis the heat balance. Puts forward the optimized amoun of cooling flushing oil based on thermal equilibrium analysis under different flushing oil quantities, this can provide theory basis for the cooling of free fall brake. |
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