目前国内外使用的打桩锤不外乎冲击式和振动式两大类。冲击式打桩锤如柴油锤,构造简单,使用方便,但是随着锤重的增加和应用的日益广泛,它所产生的公害—噪声,冲击波及范围和大气污染越发严重,使得柴油锤在城市施工中受到一定限制;而振动式打桩锤是使桩体产生高频振动,当桩的强迫振动与土壤颗粒的自振频率接近时,土壤颗粒产生共振,此时颗粒产生最大的振幅,在足够的振动加速度下,使桩和其附近土壤间的粘结力得到破坏,土壤结构呈现“准流体”状态,减小了沉桩阻力,这样桩在自重及较小的附加压力作用下便可沉入土中。常用的机械偏心式振动锤是靠电机驱动偏心块旋转而产生强迫振动,液压偏心式振动锤的工作原理是液压马达驱动偏心块旋转产生高频振动并传递给桩体;电液—液压缸式 At present, the hammers used at home and abroad are nothing but impact and vibration. Impact hammers, such as diesel hammers, are simple in construction and easy to use. However, as hammer weights increase and applications become more widespread, the nuisances, noise, shock waves, and atmospheric pollution that they generate are increasingly severe, making diesel hammers in urban areas. It is subject to certain restrictions; the vibratory hammer is used to generate high-frequency vibration of the pile. When the forced vibration of the pile is close to the natural vibration frequency of the soil particles, the soil particles resonate. At this time, the particles have the largest amplitude and are sufficient. Under vibratory acceleration, the bond between the pile and its nearby soil is destroyed, the soil structure assumes a “quasi-fluid” state, and the pile-pile resistance is reduced, so that the pile can sink under its own weight and a small additional pressure. In the soil. Commonly used mechanical eccentric vibratory hammers rely on the motor to drive the eccentric block to rotate to generate forced vibration. The working principle of the hydraulic eccentric vibratory hammer is that the hydraulic motor drives the eccentric block to rotate to generate high-frequency vibration and transmit to the pile body; the electrohydraulic-hydraulic cylinder type