【作者】 杨东；

【导师】 夏唐代；

【作者基本信息】 浙江大学 ， 岩土工程， 2013， 博士

【摘要】 大直径现浇混凝土薄壁筒桩(CTP)作为一种新桩型,目前已在我国的公路软基处理、海堤及码头工程、深基坑围护、建筑物基础处理等工程中得到广泛的应用。然而,该种桩型的理论研究远落后于工程应用,随着应用范围的日益扩大,对其理论分析、试验研究以及计算方法的研究、探讨和分析变得日益迫切。目前国内对CTP桩在竖向荷载作用下的性状进行了大量的分析,然而对其在水平荷载作用下的性状研究却较少,这严重制约着CTP桩的推广与应用。针对这些问题,本文在前人研究的基础上,首先介绍了高速公路CTP桩加固路堤的试验研究情况,然后推导了CTP桩土水平抗力的解析解,编程分析了CTP桩抗水平力性状,对CTP桩海堤和基坑围护进行了研究,所做的工作如下：1)根据广东珠江三角洲环形高速公路西环段的现场试验和观测数据,分析了CTP桩桩承式加筋路堤的荷载-沉降、抗滑移等工程性状以及拉膜效应和土拱效应的作用。2)根据考虑变形效应的主被动土压力与桩-土间摩擦力理论,并参考前人对圆筒结构土抗力分布的研究成果,推导出CTP桩在某深度处的水平抗力H(z,y)的解析解并与目前常用的几种方法进行了比较,进而分析了不同桩土参数下的大直径CTP桩的H-y曲线。3)根据CTP桩水平抗力解析计算结果,从刚性桩和柔性桩两种情况,分别把桩视为刚性体和弹性地基梁,应用有限差分法,编制计算程序,求解CTP桩的变形和内力,并与现场试验数据和其他方法进行比较,检验此方法的适用性,进而分析桩、土各参数对CTP桩水平受力性状的影响。研究显示,该方法可以考虑土抗力的非线性和有限性(即不随位移的增加而无限增大),比目前常用的m法更接近实际,比p-y曲线法更容易取得参数。4)介绍了CTP桩海堤和基坑支护体系特点和计算方法。在前文单桩抗水平力分析方法基础上,计算分析了CTP桩海堤和基坑支护体系的内力和位移,并分析了各因素对其的影响。更多还原

【Abstract】 The cast in situ concrete large diameter tubular pile (CTP) now has been widely used in our country’s construction projects, such as sea dike, retaining and protecting for foundation excavation and composite foundation of highway and building. But as all new construction technologies, the behindhand in theoretical research hampered its applications, particularly in the behavior of laterally loaded CTP piles. So based on the previous research work of others, the main works of this dissertation are shown as follows:1) The field test of Guangdong highway CTP pile composite foundation was introduced. According to field test and in-situ observation, the bearing and settlement law of Geosynthetic-reinforced CTP pile-supported embankments was analyzed.2) Based on the earth pressure theory and interface friction theory considering the displacement effects, the supporting force of soil to the CTP pile (H(z,y))was deduced. Then the effects of pile and soil parameters including the pile diameter, the depth and the internal friction angle, the cohesive strength and the bulk density of soil were analyzed.3) Based on the supporting force formula deduced in this dissertation, effects of parameters piles and soil on lateral bearing capacity of rigid piles were studied. It was found that the lateral bearing capacities of rigid piles have important relation with the cohesion and internal friction angle of soil. But the effects of friction coefficient of pile-soil interface on the lateral bearing capacities of rigid piles were negligible.4) The deflection differential equation of elastic beams was introduced, considering the soil supporting force, the horizontal displacement and internal force of CTP pile could be solved by Finite Difference Method and MATLAB. Further discipline on mechanical characteristics of laterally loaded piles probed by changing the pile diameter, pile length and soil parameters.5) The design and construction of sea dikes using CTP piles were discussed. Using the program based on the method of this dissertation, the horizontal displacement and internal force of CTP piles of sea dikes were calculated, and the effects of soil reinforcement were analyzed.6) The using on CTP piles on building foundation pits was discussed, and the analyze method based on the earth pressure theory considering the displacement effects was deduced. After comparing the calculated results with the measured values, the results were close to the measured values. Meanwhile, the influences of many factors, such as the soil reinforcement, the stiffness and position of the brace on the horizontal displacement of pile-brace support system were investigated thoroughly.更多还原