| 摘要: |
| 混凝土芯砂石桩是由高强度预制混凝土芯桩和透水的砂石外壳组合而成, 常采用振动沉管施工工艺进行软土地基加固。针对混凝土芯砂石桩新颖的桩型特点，对软黏土地基中振动沉管工艺引起的成桩效应及其特性进行了现场测试分析和理论计算研究。通过对远距离四桩施工全过程、全场地持续施工过程进行孔压、周边土体深层水平位移和混凝土芯桩桩身应力的实时跟踪监测，得到各监测量的变化规律和特点，揭示了振动沉管持续施工对各监测量消长变化的累积特性，指出振动沉管施工过程综合了静、动荷载对地基土的共同作用，体现荷载传递引起的能量在时间和空间上持续累积的特点。运用圆孔扩张理论对混凝土芯砂石桩沉管挤土的超静孔压和径向位移进行计算，探讨了理论解答与实际情况的适应性。 |
| 关键词: 混凝土芯砂石桩 振动沉管 成桩效应 累积特性 圆孔扩张理论 |
| DOI：10.12170/201901003 |
| 分类号:TU472 |
| 基金项目:国家自然科学基金青年基金资助项目（51208321)；江苏省交通科学研究计划项目（05y18） |
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| Study on compaction effect and its accumulation characteristics of concrete-core sand-gravel pile with vibrating immersed tube technology |
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TANG Tongzhi, MING Jingping, GUAN Yunfei, ZHAO Weibing
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Nanjing Hydraulic Research Institute， Nanjing
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| Abstract: |
| Concrete-core sand-gravel pile is composed of high strength precast concrete-core pile and permeable sand-gravel shell， and vibrating immersed tube technology is often used to reinforce soft soil foundation. In view of the characteristics of the new-type concrete-core sand-gravel pile，the compaction effect and its characteristics caused by the vibrating immersed tube technology in soft clay foundation are tested and analyzed on site and calculated theoretically. Through the whole process of long-distance construction of four piles and the continuous construction of the whole site， the real-time tracking and monitoring of the pore water pressure， the deep horizontal displacement of surrounding soil and the stress of concrete core pile body are conducted. The variation rules and characteristics of each monitoring quantity are obtained. This study reveals the effects of the cumulative characteristics of the continuous construction of vibrating sunken tube on the variation of each monitoring quantity， points out that the construction process of vibratory sunken tube integrates the combined action of static and dynamic load on foundation soil， and brings to light the characteristics of continuous accumulation of energy in space and time caused by load transfer. Based on the theory of cavity expansion， the excess pore water pressure and radial displacement of the concrete-core sand-gravel pile submerged pipe are calculated and the adaptability of theoretical solution to practical situation is discussed. |
| Key words: Concrete-cored sand-gravel pile vibrating immersed tube compaction effect accumulation characteristic cavity expansion theory |
