Experimental Research On The Mechanism Of High-voltage Pulse Discharge Pile

Pile foundation has been widely adopted in the underlying project because of high carrying capacity, simple construction methods, good economic returns. Currently, the pile has hundreds kinds of species, one of which of the mostly widely used type is the reaming pile, pile construction method of reaming has many kinds, including mechanical reaming, vibration expanding, hand-dug expansion, water jet reaming, drilling expansion, explosive expansion, rammed and other methods. The reaming methods there are some technical problems and economic irrationality, and the pile effect is not particularly obvious. so in the actual application process has some limitations. Russia is now trying to study shock waves generated by high-voltage pulse in liquid medium to discharge pressure pile, and made some achievements in scientific research. But our country is little or gaps in the field on studying expanding pile to use the high-voltage pulse discharge technology, through access to a large number of related literature, The ideas and research of this paper are identified based on the current research situation and the research results.In this paper, working principle of high voltage pulse discharge device is analyzed, and analyze and select the the charging circuit, discharge circuit, and charge and discharge of electrical circuit components, and introduce briefly the new composition structure of high-voltage pulse discharge device, performance, and availability. The paper focuses on the choose of the device while charging capacitors, high voltage transformers, high voltage silicon stack and current limiting resistor, discharge gap switch, the discharge cable and electrode gap choice. To chose correctly the electrical components o ensure the discharge device has a good performance, give full play to their pile effect. to establishing a mathematical model to high voltage pulse discharge on the expansion of the discharge channel. Hydraulic power generated by the discharge, the relationship between the rate and radius of channel expansion is derived by from the spherical model and the cylindrical model. high-voltage pulse discharge expanding radius is derived theoretically, and Deformation mechanism of soil around the pile is analyzed. The results show that the discharge produced by hydraulic pressure, flow velocity s directly proportional towith the discharge energy, is directly proportional to the radius is inversely proportional relationship with the model.on-site pile experimental is carried out by using new high-voltage pulse discharge devices, results show that when the high-voltage pulse discharge, the greater choice of energy parameters, the larger changes in the value of the pile diameter, the more obvious the effects. This is because the pile of soil compaction is complete before, the higher pulse energy, the greater the pressure generated by the shock wave, causing spread to pile more pressure to the soil, so soil around the pile has a large plastic deformation, to the purpose of expanding effect. The pore size changes gradually with the increase in the number of discharges larger, when energy in the pulse is alike, This is because after the end of each discharge, on the role of soil around the pile will have a pressure peak, leading to soil effective stress increases, so the soil around the pile after each pulse will have a certain amount of plastic deformation, but with the pile density of soil pushed the same time, it's deformation modulus is constantly increasing, before the soil around of the pile the pile is completely compacted, the pile diameter changes is proportional to the number of pulses to discharge, while increasing number of pile diameter decreasing trend as increasing with each the density conditions way of the soil of pile.High-voltage pulse discharge test pile is still first in the country, changes of diameter of pile of high-voltage pulse discharge were formula using knowledge of soil mechanics in this paper, It can be determined by test results:derived formula can be used to evaluate the variation of pile diameter under high-voltage pulse discharge, can be provide a reference for future research and design.