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根据炎热多雨地区轨道交通周边土体的实际工程状态,开展经历不同干湿循环过程的花岗岩残积土的共振柱试验,研究炎热多雨气候影响下残积土小应变下的刚度特性。结果表明,受反复干湿循环效应影响,在10~(-6)~10~(-4)小应变范围内,残积土G_(max)随干湿循环次数n的衰变规律与常应变下黏性土强度特性衰减规律有较大差异,最大衰减出现在干湿循环中期;经历多次循环后,小围压下残积土的G–γ关系曲线出现直线下降和骤降阶段;利用Martin–Davidenkov模型和经验关系能较好地反映G/G_(max)和D随γ的变化规律,发现不同干湿循环次数后,G/G_(max)–γ关系随围压增大逐渐出现“两极分化”现象。研究还从微观角度对残积土小应变刚度特性的干湿循环效应给与解释,说明炎热多雨气候下残积土刚度的力学行为是由于结构强度减损、微观结构重塑引起。研究可为轨道交通工程动力参数的选取,类似工程场地的设计、施工及抗震分析提供技术参考依据。
According to the actual engineering conditions of the soil around the rail transit in hot and rainy areas, the resonance column test of granite residual soil subjected to different wetting and drying cycles was carried out to study the stiffness characteristics of the residual soil under the small strain under the influence of hot and rainy weather. The results show that under the influence of repeated wetting and drying cycles, the G_ (max) of residual soil varies with the number of cycles of wet and dry cycles n and the normal strain becomes constant within the range of 10 ~ (-6) ~ 10 ~ (-4) The attenuation of strength characteristics of soils is quite different. The maximum attenuation appears in the middle of the wet-dry cycle. After repeated cycles, the G-γ curve of the residual soils under a small confining pressure shows a straight-line decline and a sudden drop. By using Martin-Davidenkov The relationship between G / G max and D with γ can be well reflected by the model and empirical relationship. It is found that G / G max -γ relationship gradually increases with the increase of confining pressure after different cycles Differentiation "phenomenon. The study also explained the effect of microcosmic stiffness of the residual soil from the microscopic point of view on wetting and drying cycles. It is shown that the mechanical behavior of the residual soil stiffness under hot and rainy conditions is caused by the decrease of structural strength and remodeling of the microstructure. The research can provide technical reference for the selection of dynamic parameters of rail transit engineering, design, construction and seismic analysis of similar engineering sites.