【作者】 林奇；

【导师】 陈龙珠；

【作者基本信息】 上海交通大学 ， 防灾减灾工程及防护工程， 2011， 硕士

【摘要】 由于现代化城市对环境保护的要求日趋严格,施工过程引起环境振动的桩基施工机械受到越来越多的限制。为解决城市地区桩基础施工的环境影响问题,国内外近十多年来发展和推广高频液压振动沉桩技术。虽然该技术在工程界已被逐渐应用,但是对沉桩过程中土的动力特性变化研究还是不足。本文在总结国内外既有研究成果基础上,利用组装高频振动测试系统分别对干砂、饱和砂土进行高频振动测试试验;同时,对饱和砂土与饱和软粘土在2～10Hz范围内进行动三轴试验。主要工作包括:(1)利用实验室现有静力固结仪和电磁式激振器等仪器设备,组装一套可用于高频振动测试的系统。该系统工作频率18～2000Hz,变形测量精度为1μm,可以持续输出恒定峰值动荷载。(2)采用高频振动测试系统对相对密实度为33%和66%的干砂,在侧限和振动频率为18～42Hz条件下进行振动试验,着重探讨了干砂土残余变形与振动频率的变化关系,并考察了相对密实度、动应力幅值的影响。(3)对不同相对密实度、不同动应力幅值下饱和砂土进行高频振动试验,研究饱和砂土残余变形与振动频率关系;并且与干砂土试验结果比较,分析饱和砂土与干砂土不同振动频率下残余变形的差异。(4)在固结比为1.0,围压为250kPa、500kPa条件下,对饱和砂土和饱和软粘土在振动频率处于2～10Hz范围内进行动三轴试验,探讨了振动频率对动模量、阻尼比的影响;分析不同振动频率下饱和砂土与饱和软粘土孔隙水压力变化规律。本文是国家自然科学基金资助项目(50779034)的一部分。更多还原

【Abstract】 Owing to the requirements on environmental protection in modern cities, the application of pile construction machinery which arousing environmental vibration in process of construction has been constrained. In order to alleviate the environmental impacts of piling driving in urban areas, piling with high-frequency vibration was developed and gradually used abroad over recent 10 years. However, there is little work focus on the soil dynamic characteristics in process of piling.In this thesis, the dry and saturated sands are employed to perform high-frequency vibration experiment test. It is also employed to perform cyclic tri-axial tests for saturated sand and saturated clay. The main contents are as follows:(1) Making the use of present instrument and equipment including static consolidation apparatus and electromagnetic vibration exciter to assembling a test system with high-frequency vibration. Its working frequency is between 18~2000Hz, and accuracy of deformation measurement is 1μm, and also can supply with dynamic load of constant peak.(2) A series of vibration compaction tests were done by "the system of high-frequency vibration experiment test" for dry sand of the relative density 33%、66%, under lateral confinement with vibration frequencies 18~42Hz. The relationship of dry sand between residual deformation and vibration frequency was investigated. The influence of relative density and amplitude of dynamic stress were also analyzed for the relationship between vibration frequency and residual deformation.(3) Experimenting on the "the system of high-frequency vibration experiment test" with saturated sand of different relative density and different amplitude of dynamic stress, the relationship between residual deformation and vibration frequency was investigated for saturated sand. Comparing the results with those of the dry sand and discussing the differences of residual deformation between saturated sand and dry sand were followed then.(4) The soil dynamic tri-axial test was employed for saturated sand and saturated clay with vibration frequency 2~10Hz under consolidation ratio 1.0 and confining pressure250kPa and 500kPa.The effect of vibration frequency were carried out emphasis on dynamic modulus, damping ratio and the change patterns of the generation of pore water pressure under different vibration frequency were analyzed.The research work presented in this thesis was supported by the National Natural Science Foundation of China with the granted number 50779034.更多还原