Structural and geotechnical interpretation of strain gauge data from laterally loaded reinforced concrete piles
Structural and geotechnical interpretation of strain gauge data from laterally loaded reinforced concrete piles
复制标题
DOI：
--
复制
发表时间：
2011-05
期刊：
影响因子：
--
通讯作者：
Nicola Biocchi
中科院分区：
文献类型：
--
作者：
Nicola Biocchi
我们分析了四个已安装仪器的地点，共14根桩柱，以了解桩柱的结构特性和已加固斜坡的岩土特性。振弦应变计用于计算施加在桩上的弯矩，而测斜仪用于测量位移。对仪器进行了审查，并制定了处理和分析应变计数据的方法。混凝土是一种性能复杂的材料。收缩，徐变，开裂，温度变化，混凝土的强度和弹性模量进行了严格的分析，以了解它们对混凝土桩的行为和应变计的功能的影响。结果表明，饱和粘土中地下钢筋混凝土结构的徐变和收缩效应可以忽略不计，而开裂效应和温度变化则需要具体情况分析。提出了一种考虑应变片热膨胀系数与混凝土热膨胀系数差异的修正方法。分析了两种桩型，标准钢筋混凝土桩和圆形钢管混凝土桩。审查他们的行为在弯曲，认为裂纹的发展。考虑到实际应力/应变曲线和混凝土开裂的影响，开发了两种计算桩弯矩的方法。弯矩的结果进行了比较，使用现有的曲线拟合方法的改进版本的测斜仪剖面。比较表明，两种仪器的结果之间的良好的协议。一个关键的分析桩/土的行为进行了比较的结果，从仪器化的网站与理论机制滑坡稳定桩在其他地方。结果表明，与理论机制，以及表明，斜坡已成功稳定良好的匹配。在分析监测数据期间还进行了其他观察。这包括气候和植被对稳定斜坡的季节性影响，以及横向受载圆形钢管混凝土桩外部灌浆环的结构效应
Four instrumented sites, with a total of 14 instrumented piles, have been analysed to understand the structural behaviour of the piles and the geotechnical behaviour of the stabilised slopes. Vibrating wire strain gauges are used for the calculation of the bending moment applied to the piles, while inclinometers are used to measure the displacements. A review of the instrumentation has been carried out and a methodology for processin and analysing strain gauges data has been developed. Concrete is a material with a complex behaviour. Shrinkage, creep, cracking, temperature variations, strength and modulus of elasticity of concrete are critically analysed to understand their influence on the concrete pile behaviour and on the function of the strain gauges. The results show that creep and shrinkage effects can be neglected in underground reinforced concrete structures in saturated clay, while cracking effects and temperature variations have to be analysed case by case. A correction method has been developed to consider the difference between the coefficient of thermal expansion of the strain gauges and that of the concrete. Two types of pile have been analysed, standard reinforced concrete piles and circular concrete-filled steel tubular piles. A review of their behaviour in bending that considers the development of cracking is presented. Two methods for the calculation of bending moment in the piles have been developed taking into account realistic stress/strain curves and the effects of concrete cracking. The bending moment results are compared with the inclinometer profiles using an improved version of an existing curve fitting method. The comparison shows good agreement between the two instrument results. A critical analysis of the pile/soil behaviour has been carried out comparing the results from the instrumented sites with theoretical mechanisms for landslide stabilising piles presented elsewhere. The results show a good match with the theoretical mechanisms as well as showing that the slopes have been successfully stabilised. Other observations have been made during analysis of the monitoring data. These include the seasonal effects of climate and vegetation on stabilised slopes and the structural effect of the external grout ring in laterally loaded circular concrete-filled steel tubular piles