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通过覆盖上海地区两种沉积相(滨海平原和湖沼平原)19个工程的原位十字板强度Su FV,结合国内外研究成果,对上海3个软黏土层的超固结比OCR及其地质成因进行了分析。根据强度比S_(uFV)/σ’_(v0)(σ’_(v0)为有效上覆压力)计算OCR,给出了OCR随深度的变化规律。上海软土整体上处于超固结状态,浅部具有较大的OCR且较为离散(在1.3~5.0),随深度的增加OCR迅速减小,超过约13 m后维持在一稳定的数值(平均为1.6)。过去采用室内压缩试验给出的结果显著低估了上海软黏土的OCR。结合Hanzawa和Tanaka给出的模型对上海软黏土的强度及超固结地质成因进行了分析,认为基本符合浅部以胶结作用为主、深部以次压缩为主的特征。浅部的胶结作用变化范围较大而深部的次压缩作用则相对稳定,并初步给出了正常压缩、胶结作用和次压缩作用对总强度的贡献。
By covering the Su FV of 19 projects in two sedimentary facies (coastal plains and lakeshore plains) in Shanghai, combining with the research results at home and abroad, the overconsolidation ratio OCR of three soft clay layers in Shanghai and its geological causes Analyzed. The OCR is calculated according to the intensity ratio S_ (uFV) / σ ’_ (v0) (σ’ _ (v0) as the effective overburden pressure), and the variation rule of OCR with depth is given. The soft clay in Shanghai is in an overconsolidated state as a whole, with a large OCR in the shallow part and relatively discrete (1.3 ~ 5.0). The OCR decreases rapidly with increasing depth and maintains a stable value after about 13 m Is 1.6). In the past, the results obtained using the indoor compression test significantly underestimated the OCR of Shanghai soft clay. Based on the model given by Hanzawa and Tanaka, the strength of soft clay in Shanghai and the geologic cause of overconsolidation are analyzed, which are basically consistent with the features of shallow cementation and deep sub-compression. The shallow cementation has a wide range of variation and the deep sub-compression is relatively stable, and the contribution of normal compression, cementation and sub-compression to the total strength is preliminarily given.