挤密砂桩振动沉桩可打性分析中必要振幅的试验研究

Experimental study on the necessary amplitude in the analysis of the drivability of compacted sand pile vibration driving

击振力和振幅是挤密砂桩振动沉桩可打性分析中2个最重要的参数,其中工作振幅与机械设备能力及土性相关,而必要振幅主要与土性相关。现有的振动沉桩可打性分析理论在必要振幅的认识方面存在较大的差异。为了更好解决振动沉桩必要振幅预测问题,依托港珠澳桥隧人工岛工程挤密砂桩可打性分析课题,通过在砂桩管上安装加速度传感器对挤密砂桩沉桩过程进行全程监测,并通过二次积分得到振幅-时程曲线,将各个土质条件下实测振幅与目前常用的日本建调神户株式会社法、美国ICE沉桩理论以及法国PTC沉桩理论进行对比分析,根据实测结果,对上述振动沉桩理论的适用性及优缺点进行了对比分析并给出了必要振幅取值方法的建议。研究结果表明,在采用电动振动锤沉桩的条件下,日本建调神户株式会社法必要振幅的取值偏大,法国PTC法的必要振幅偏小,美国ICE法必要振幅的取值规律性与实测结果吻合良好,但是取值方法不够具体。建议在美国ICE法的基础上结合工程经验进一步细化和完善振动沉桩必要振幅取值。

The vibration force and amplitude are the two most important parameters in the analysis of the drivability of compacted sand pile vibration driving.The working amplitude is related to the mechanical equipment capacity and soil properties,while the necessary amplitude is mainly related to soil properties.There are significant differences in the understanding of necessary amplitudes among the existing theories for analyzing the drivability of vibration driven piles.In order to better solve the problem of predicting the necessary amplitude for vibration pile driving,based on the analysis of the drivability of compacted sand piles in the artificial island project of the Hongkong-Zhuhai-Macao Bridge and Tunnel,an acceleration sensor is installed on the sand pile pipe to monitor the entire process of compaction sand pile driving.The amplitude time curve is obtained through quadratic integration.The measured amplitude under various soil conditions is compared and analyzed with commonly used methods such as the Jiandiao Kobe Corporation Law of Japan,the ICE pile driving theory in the United States,and the PTC pile driving theory in France.Based on the measured results,the applicability and advantages and disadvantages of the above vibration pile driving theory are compared and analyzed,and suggestions for the necessary amplitude value method are given.The research results indicate that under the condition of using an electric vibration hammer for pile driving,the necessary amplitude of the Jiandiao Kobe Corporation Law of Japan is larger,the necessary amplitude of the French PTC method is smaller,and the regularity of the necessary amplitude of the American ICE method is in good agreement with the measured results,but the value method is not specific enough.It is recommended to further refine and improve the necessary amplitude values for vibration pile driving based on the ICE law in the United States and engineering experience.