Reliability-Based Verification of Serviceability Limit States of Dry Deep Mixing Columns

Johan Spross,Stefan Larsson,Niclas Bergman

doi:10.1061/(asce)gt.1943-5606.0002458

Abstract

AbstractDeep mixing columns commonly are used to reduce settlement under road and railway embankments on soft soils. However, the structural behavior of the soil volume improved with columns is dif...

Highlights

In the construction of road and railway embankments on soft clays, measures typically need to be taken to reduce the effect of consolidation settlement on the structure
This paper modeled the complex settlement behavior of soil reinforced by deep mixing columns with an updated version of the well-established Voigt model, which assumes an equal strain in the soil and the column as well as no lateral deformation; Broms (1991) and Han (2015) discussed these assumptions
The value of a that corresponded to the assigned pFT was close to 0.37, indicating that the initial design should have an area ratio less than this value. This is an effect of the conditional criterion for observing a tip resistance above the established threshold, i.e., qfcobsg

Summary

Introduction

In the construction of road and railway embankments on soft clays, measures typically need to be taken to reduce the effect of consolidation settlement on the structure. Soil improvement through the installation of deep mixing columns commonly is used for this purpose. The wet deep mixing method is dominant in terms of execution, but in northern Europe, Japan, and Thailand, the dry deep mixing method is commonplace, it is used sparsely in other regions. The dry deep mixing method was developed mainly in Japan and the Nordic countries during the 1960s and 1970s (e.g., Broms and Boman 1975; Okumura and Terashi 1975). The difference between the two methods lies in whether the binder is distributed into the soil as a dry powder or as a slurry before the mixing. There is no principal difference between the methods in terms of the analysis of limit states

Methods

Results

Discussion

Conclusion