Statistically Quantifying the Uncertainty in Strength of Marine Clay Stabilized by a Type of Portland-Fly Ash Cement

Zhi-Ren Zhu,Qiang-Qiang Cheng,Elton J Chen,Yuan Su,Yang-Yang Chen,Yong Liu

doi:10.1155/2021/6654802

Abstract

This study deals with the variation in strength of clays stabilized by a special binder—the CEM II/B-V type of Portland-fly ash cement. Two sources of uncertainties were examined, that is, the uncertainty in cement fraction in the binder, and the nonuniformity in binder concentration resulted from the process of mixing binder slurry with in situ clays. These two uncertainties were quantitatively described as two random variables, and the analyses were conducted through the Monte Carlo simulation method. Results indicate that the strength is insensitive to the cement fraction in the binder but is sensitive to the binder concentration; the variation of the latter even results in an amplified variation of strength. The variation of binder concentration is proposed to be linked up with the variation of strength through the operational parameter of blade rotation number. By doing so, the results could benefit designers in quality control prior to the construction of soil stabilization.

Highlights

Soil stabilization is necessary prior to the constructions of many geotechnical projects in marine clay. e stabilization can be realized by adding cementitious binders or other admixtures into natural clays with the deep soil mixing or jet-grouting techniques
Xiao et al [2] found that the coefficient of variation (COV) of the unconfined compressive strength (UCS) of Portland-fly ash cement (PFC)-stabilized clay samples prepared in laboratory is generally less than 0.05. is level of COV is negligible when compared to that reported from deep cement mixing projects; the latter is often as high as 0.4 to 0.6 ([6]). is discrepancy implies a gap between laboratory studies and Advances in Civil Engineering
Four parameters of the random variable α can be Figure 8 shows the effects of α and β on the strength with the Monte Carlo simulation method [12]. e curing period is α : binder concentration β β : cement fraction in binder α

Summary

Introduction

Soil stabilization is necessary prior to the constructions of many geotechnical projects in marine clay. e stabilization can be realized by adding cementitious binders or other admixtures (e.g., lime, fly ash, and bitumen) into natural clays with the deep soil mixing or jet-grouting techniques. Many projects have a long construction period; for instance, when applying a cement-admixed slab in a deep excavation to resist the lateral displacement ([1]), the excavation may last half a year after the completion of the slab. In this circumstance, a low strength gaining rate is allowable. Xiao et al [2] found that the coefficient of variation (COV) of the unconfined compressive strength (UCS) of PFC-stabilized clay samples prepared in laboratory is generally less than 0.05. A rule-of-thumb estimation of the variation in strength can be obtained for construction quality control

Strength Prediction Model

State Variables

Results

Conclusions