Evolution of the properties of lime-treated silty soil in a small experimental embankment
Evolution of the properties of lime-treated silty soil in a small experimental embankment
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DOI：
10.1016/j.enggeo.2015.03.008
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发表时间：
2015-05
影响因子：
7.4
通讯作者：
Lamis Makki-Szymkiewicz;A. Hibouche;S. Taibi;G. Herrier;D. Lesueur;J. Fleureau
中科院分区：
文献类型：
--
作者：
Lamis Makki-Szymkiewicz;A. Hibouche;S. Taibi;G. Herrier;D. Lesueur;J. Fleureau
为了研究石灰处理粉质土在现场搅拌、铺设、压实和环境条件下的演变，在法国西北部鲁昂附近建造了一个实验堤;该堤长25 m，顶部宽4 m，高1.8 m。虽然特别注意将土壤和石灰混合得非常彻底，精确测量水量，使用振动羊蹄压路机压实土壤，但建筑条件通常用于建造所有其他方面的建筑。在工程完成后约1个月、6个月和12个月从堤坝上取样，并进行三轴和体积测量试验。为了比较处理前后土的性质，在附近修建了一个与粉质土相似的小型"参考"路堤，利用原始应变测量装置对处理前后土的非饱和土试样进行了小应变三轴试验。轴向割线模量的变化可以用幂律E = β σ 1m来描述，其中β是取决于固化时间的参数，m几乎是常数对饱和处理和未处理的试样进行CU和CD大应变三轴试验，在10至300 kPa的围压下固结，结果表明粘聚力随养护时间有一定的增加，摩擦角几乎不变。研究了使用非线性失效准则的可能性。压缩系数Ciso（[log（p ′），e]坐标系中临界州线（CSL）的斜率）在处理后显著低于未处理的试样，但其值与固化时间无关。同时，处理后的试样的CSL高于未处理的粉土。材料的脆性，从峰值残余偏应力比qpeak/qresis的处理和未处理的标本是相同的，是独立的固化时间和围压。然而，对应于CD曲线的峰值的轴向应变在未处理的试样中比在处理的试样中高得多。饱和石灰处理土的渗透性（10 − 9m/s）与未处理土的渗透性相同。路堤建成一个月后测得的值不随时间或围压而变化。本研究的结果证实了以前的研究实验室制备的非饱和试样：他们已经证明了石灰处理的有效性，在更困难的环境中的一个真实的工作现场，并表明，石灰处理的样品提出了显着的收益，其工程性质，即使饱和，提供石灰和水的剂量，混合和压实条件进行了仔细控制。由此获得的新材料呈现出较低的塑性、改进的可加工性、增加的刚度和内聚性，而在脆性或渗透性方面没有任何性能损失。
In order to study the evolution of a lime-treated silty soil under in-situ conditions of mixing, laying out, compaction and environment, an experimental dike was built near Rouen, in northwest France; this dike is 25 m long, 4 m wide at the crest and 1.8 m high. While special care was taken to mix the soil and lime very thoroughly, to precisely measure the quantity of water, to compact the soil using a vibrating sheepsfoot roller, the building conditions were those usually used to construct embankments in all other respects. Samples were taken from the dike approximately 1 month, 6 months and 12 months after the completion of the work and underwent triaxial and oedometric testing. To compare the properties of treated soil with those of untreated soil, another smaller “reference” embankment was built nearby under similar conditions with silty soil.Small-strain triaxial tests were performed on unsaturated specimens of treated and untreated soil using an original strain measurement device. The change in axial secant moduli can be described by a power law E = βσ1m, where β is a parameter that depends on curing time and m is nearly constant (m ≈ 0.45).CU and CD large-strain triaxial tests carried out on saturated treated and untreated specimens, consolidated under confining stresses ranging from 10 to 300 kPa, showed a definite increase in cohesion as a function of curing time, with nearly unchanged friction angles. The possibility to use a non-linear failure criterion was examined. The compressibility coefficient Ciso, slope of the critical state line (CSL) in the [log(p′), e] coordinate system, is significantly lower in treated than untreated specimens, but its value remains constant whatever the curing time. At the same time, the CSL of the treated specimens is above that of the untreated silt. The brittleness of the material, derived from the peak to residual deviator stress ratio qpeak/qresis the same for treated and untreated specimens and is independent of curing time and confining stress. However, the axial strain corresponding to the peak of CD curves is much higher in untreated than in treated specimens. The permeability of the saturated lime-treated soil (10− 9m/s) is the same as that of the untreated soil. The value measured one month after the embankment was constructed, does not change with time or with the confining stress. The results of the present study confirm those of previous studies on laboratory-prepared unsaturated specimens: they have demonstrated the effectiveness of lime-treatment in the much more difficult environment of a real working site and shown that lime-treated samples present a significant gain in their engineering properties, even when saturated, provided that the dosage of lime and water, mixing and compaction conditions are carefully controlled. The new material thus obtained presents lower plasticity, improved workability, increased stiffness and cohesion without any loss of performance in terms of brittleness or permeability.