Effect of in situ water content variation on the spatial variation of strength of deep cement-mixed clay

Abstract

This paper examines the interaction between the spatial variations in binder concentration (i.e. cement slurry concentration) and in situ water content, in cement-mixed soil, using field and model data as well as statistical analysis and random field simulation. The field data are first analysed to shed light on the spatial variation in the in situ water content, including its scale of fluctuation. A statistical model is then developed which takes into account the variation in binder concentration and in situ water content. This leads to a two-parameter model for the prediction of the mean, variance and probability distribution function of the strength of the cement-treated soil. The scale of fluctuation for the variation in binder concentration arising from imperfect mixing within a cement-mixed column is then examined using centrifuge model data. This indicates that the scale of fluctuation in binder concentration is much shorter in range than that of the in situ water content. The combined effect of these two scales of fluctuation is then studied by simulating the resulting random field using Monte-Carlo simulations. This indicates that the size of the sampling region has a significant effect on the scale of fluctuation that is captured. If the sampling region is of a similar size to the column diameter, the measured scale of fluctuation reflects that of the binder concentration. As the size of the sampling region increases, so does the measured scale of fluctuation. This explains the wide range of scales of fluctuation that have been reported for cementtreated soil. To capture both scales of fluctuation in core sampling, some boreholes should be sunk at close spacings of less than a column diameter, in order to capture short-range variation.

Experimental Study on Unconfined Compression Strength of Polypropylene Fiber Reinforced Composite Cemented Clay

“…Soft clays are widely present in offshore areas and cannot be used directly in geotechnical engineering activities, such as subgrade engineering, embankments, deep excavation and underground construction. Considering the economy and effectiveness, using cement to reinforce soft clay is of great popularity [3][4][5][6][7][8], compared with other chemical stabilization methods. Though cement-stabilized clay has the advantages of rapid formation, good plasticity and high compressive strength, it also has the disadvantages of low tensile strength and flexural strength.…”

Investigation on the Triaxial Mechanical Characteristics of Cement-Treated Subgrade Soil Admixed with Polypropylene Fiber

“…It is necessary to make ground improvements to avoid serious damage to the roadbed, pavement, and even the upper road structures [1][2][3][4]. As a typical example of the chemical improvement method, cement soil is widely applied to various roadbed treatment projects due to its advantages of good integrity, strong water stability, and low cost [5][6][7][8][9]. However, a large number of tests show that, due to the defects of low tensile strength, large brittleness, and poor deformability, cement soil is not suitable for every kind of project [10][11][12][13].…”

Engineering Characteristics and Reinforcement Approaches of Organic Sandy Soil

“…It should be noted that the cement-admixed organic sandy soil possesses a high variability in its engineering mechanical indices, such as the strength and stiffness [23,24]. To fully capture the variability, random fields may need to be employed [25]. As a limitation, this kind of variability was not considered in this study, which forms the scope of future investigations.…”