Soil conditioning technology is usually required to modify the excavated soil to a fluid plastic state during the construction with earth pressure balance (EPB) shield. The steady pressure distribution in the excavation face is linked to soil fluidity. Compared with the slump test, the rheological behavior of the conditioned soil can better reflect the dynamic flow characteristics. A gas-loading rotational rheometer is developed to test the rheological properties of the conditioning agents and the conditioned sandy soil, which can overcome the disadvantage of uneven mechanical loading and create gas-loading conditions. The rheological properties of sandy soil conditioned by different agents under atmospheric and gas-loading pressure conditions were studied, and the influences of foam injection ratio (FIR), bentonite slurry injection ratio (SIR), and polymer injection ratio (PIR) on soil viscosity were analyzed. The test results show that the ambient air pressure only greatly influences the experimental group with foam. Under the same gas-loading pressure, the foam’s apparent viscosity decreases with the foam expansion ratio (FER) increasing. The rheological behavior of the conditioned sandy soil conforms to the Bingham model under atmospheric pressure and conforms to the Power Law model when PIR ≤ 5 % under gas-loading pressure of 3 bar. The Weissenberg effect accounts for the differences. When PIR > 10 %, the rheological curve of three agents conditioned sand conforms to the Herschel Bulkley model. The higher content polymer reacts with bentonite to increase the soil viscosity, and blocks the foam seepage channel, making it difficult for the foam to re-enter the soil under gas-loading pressure. Investigating the rheological behavior of different conditioned sandy soil provides optimization strategies for EPB performance.

中文翻译：

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土压平衡盾构掘进气体加载压力下调理砂土的流变特性

在土压平衡（EPB）盾构施工过程中，通常需要采用土壤调理技术将开挖的土壤改性为流塑状态。开挖面的稳定压力分布与土壤流动性有关。与坍落度试验相比，调理土的流变行为更能反映动态流动特性。开发了气体加载旋转流变仪来测试调理剂和调理后的沙土的流变特性，可以克服机械加载不均匀的缺点，创造气体加载条件。研究了不同药剂在常压和充气压力条件下调节砂土的流变特性，以及泡沫注入比（FIR）、膨润土浆注入比（SIR）和聚合物注入比（PIR）对土粘度的影响进行了分析。测试结果表明，环境气压仅对泡沫实验组影响较大。在相同的充气压力下，随着泡沫膨胀比（FER）的增加，泡沫的表观粘度降低。调节后的砂土的流变行为在大气压下符合Bingham模型，在气体加载压力3 bar下当PIR≤5%时符合幂律模型。韦森伯格效应解释了这些差异。当PIR>10%时，三种药剂调理砂的流变曲线符合Herschel Bulkley模型。较高含量的聚合物与膨润土反应，增加土壤粘度，堵塞泡沫渗流通道，使泡沫在气体加载压力下难以重新进入土壤。研究不同条件沙土的流变行为为 EPB 性能提供优化策略。