Low–concentration of colloidal silica (usually from 5 to 20 wt%) for liquefaction mitigation has been widely studied. But fewer literatures have focused on higher concentration of colloidal silica for cementing sand. For calcareous sand seeped by 40 wt% colloidal silica, cyclic loadings were performed to explore its anti–liquefaction, long–term settlement and self–sensing characteristics. Cyclic triaxial apparatus were to perform anti–liquefaction and long–term settlement tests, and use self-built setup to perform self-sensing tests. The new findings are as follows: (1) for anti–liquefaction, specimens seeped by 40 wt% colloidal silica can’t achieve liquefaction, i.e., the excess pore pressure ratios cyclically fluctuates between 1 and negative, which is not discovered by lower concentration of colloidal silica in the previous literatures; (2) for long–term settlement, cumulative strain is small after 20,000 cycles, and the cumulative strain is less than 1 % even the cyclic stress ratio (CSR) is greater than 1.1, indicating that the colloidal–silica–cemented sand has good resistance to deformation; (3) self–sensing characteristics have been discovered, i.e., a stress change of 90 kPa can lead to 59.37 % change in electrical resistivity, compared to Portland–cement-treated sand without change of resistivity under the same stress change. When Portland–cemented materials are added with conductive fillers in the previous literatures, they can exhibit self-sensing characteristics, but the stress sensitivity is still two orders lower than colloidal–silica–cemented sand. For colloidal–silica–cemented sand, based on the fact that the dry silica gel is non–conductive and only the salt solution in the micro porous media is conductive, the self–sensing feature can be attributed to the stress–induced deformation of micro conductive–salt–solution–filled channels (i.e., the deformation of conductive network). The above research indicates that colloidal–silica–seeped sand has a potential for self–sensing subgrades in the marine environments.

中文翻译：

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高浓度胶体二氧化硅渗流钙质砂的自感、抗液化及长期沉降特性

用于缓解液化作用的低浓度胶体二氧化硅（通常为 5 至 20 wt%）已得到广泛研究。但很少有文献关注用于固井砂的较高浓度的胶体二氧化硅。针对掺有40 wt%胶体二氧化硅的钙质砂，进行循环加载，探讨其抗液化、长期沉降和自感知特性。循环三轴仪进行抗液化和长期沉降试验，并采用自建装置进行自传感试验。新发现如下：（1）在抗液化方面，40wt%胶体二氧化硅渗入的试件无法实现液化，即超孔隙水压力比在1到负值之间循环波动，这是较低浓度时未发现的。以往文献中胶体二氧化硅的介绍； (2) 对于长期沉降，20000次循环后累积应变较小，即使循环应力比(CSR)大于1.1，累积应变也小于1%，表明胶体硅质胶结砂具有良好的抗渗性。抗变形能力； (3)发现了自传感特性，即90 kPa的应力变化可导致电阻率变化59.37%，与相同应力变化下电阻率没有变化的硅酸盐水泥处理砂相比，电阻率变化59.37%。以往文献中硅酸盐胶结材料添加导电填料后，可以表现出自感知特性，但应力敏感性仍比胶体硅质胶结砂低两个数量级。对于胶态二氧化硅胶结砂，基于干硅胶不导电而只有微孔介质中的盐溶液导电的事实，自感知特征可归因于微孔介质的应力引起变形。导电盐溶液填充通道（即导电网络的变形）。上述研究表明，胶体硅渗砂具有在海洋环境中用于自感知路基的潜力。