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针对一定相对密度的饱和砂土,首先开展单元体K0固结试验和振动液化试验研究,发现饱和砂土液化后体变规律受再沉积和再固结两种机制制约:其中再沉积部分与所受振动历史密切相关,尤其是液化触发后的应变历史,土骨架累积剪应变比越大、再沉积体变越大;而再固结部分受先期固结历史和循环振动历史影响显著,再固结曲线会沿原有正常固结曲线趋势发展,其稳定段再压缩指数比相同条件下的正常固结曲线的压缩指数稍大。据此提出了考虑先期固结和振动历史的砂土液化后体变模型和简化算法,将再沉积和再固结两者统一表达成再固结体变,并建议了再固结压缩指数和假设起始应力的确定方法。进一步开展了水平场地地震液化离心机模型试验,监测模型固结和振动液化过程的沉降,从模型尺度进一步揭示砂土液化后体变规律,并初步验证了本文模型与简化算法的有效性。
For a certain relative density of saturated sands, first of all, K0 consolidation test and vibration liquefaction test of unit body are carried out. It is found that the volume change law of saturated sands after liquefaction is controlled by two mechanisms: re-deposition and re-consolidation It is closely related to the history of vibration, especially the strain history after liquefaction triggered. The larger the cumulative shear strain ratio of soil skeleton, the larger the re-deposited body becomes. The re-consolidation part is significantly affected by the pre-consolidation history and the cyclic vibration history, The curve of the knot will develop along the trend of the normal consolidation curve, and the compressibility index of the stable section will be slightly larger than that of the normal consolidation curve under the same condition. Therefore, the post-liquefaction body deformation model and the simplified algorithm considering the history of pre-consolidation and vibration are put forward. The re-deposition and re-consolidation are expressed as re-consolidation changes, and recombination compression index and Assume the method of determining the initial stress. Furthermore, the horizontal field earthquake liquefaction centrifuge model test was further carried out to monitor the settlement of the model consolidation and the vibration liquefaction process. The body deformation law of sand liquefaction was further revealed from the model scale, and the validity of the model and the simplified algorithm was verified.