智能化双向搅拌桩技术在引江济淮白山船闸工程中得到了推广应用,为研究白山船闸水泥土的强度变化规律以及新技术应用效果,通过制备不同形状、水泥掺量和龄期的水泥土试样,进行无侧限抗压强度试验和三轴不固结不排水试验,获得水泥土的应力应变关系、抗压强度及抗剪强度参数。室内试验结果表明:水泥土应力-应变关系为应变软化型,无侧限抗压强度随水泥掺量、龄期的增长而增大,与龄期对数近似呈线性关系;90 d龄期的圆柱体试样强度比立方体试样高约13%;变形模量与无侧限抗压强度的比值在55.6~96.2之间,受龄期影响较大;黏聚力与无侧限抗压强度呈近似线性增长关系,内摩擦角范围为22°~33°。现场芯样强度达到室内水泥土强度的70%以上,智能化双向搅拌技术能够在一定程度上改善搅拌桩成桩质量,采用强度比值的拟合关系式有利于弥补室内与现场水泥土的强度差异。扫描电镜(SEM)结果从微观角度揭示了水泥土的强度增长机理。研究成果可为类似工程研究提供依据。
Abstract
Intelligent bidirectional cement-soil mixing technology has been applied in the Baishan navigation lock of the Yangtze-Huaihe water diversion project. To investigate the strength variation of the cemented soil in the Baishan navigation lock and assess the effectiveness of the new technology, we prepared cemented soil specimens with varying shapes, cement ratios, and curing ages. These specimens underwent unconfined compressive strength tests and triaxial unconsolidated and undrained tests, allowing us to obtain the stress-strain relationship, compressive strength, and shear strength parameters. The results of the laboratory tests indicate that the stress-strain relationship of the cemented soil exhibits strain softening behavior. The unconfined compressive strength increases with the growth of cement ratio and curing age, showing an approximate linear correlation with the logarithm of curing age. Under the same conditions, 90-d age cylindrical specimens display a strength approximately 13% higher than cubic specimens. The ratio of deformation modulus to unconfined compressive strength ranges from 55.6 to 96.2 and is significantly influenced by the age of the specimens. Cohesion and unconfined compressive strength can be described as approximate linear growth relationship, and the internal friction angle ranges from 22° to 33°. The in-situ core samples exhibit a strength exceeding 70% of that of laboratory cemented soil, demonstrating that the strength ratio expression helps compensate for the strength discrepancy between laboratory and in-situ cemented soil. Scanning electron microscope (SEM) results also unveil the mechanism behind the strength growth of cemented soil from a micro perspective.
关键词
水泥土 /
无侧限抗压强度 /
抗剪强度 /
三轴试验 /
微观机理
Key words
cemented soil /
unconfined compressive strength /
shear strength /
triaxial test /
micro-mechanism
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