The in-situ deep mixing technique has been established as a means to effect columnar inclusions into soft ground to enhance the bearing capacity and reduce settlement. Since the inception of this method, developments in the plant and machinery, as well as associated field techniques, have surpassed the basic understanding of strength developments in high water-content clays admixed with cementing agents.In this paper an attempt is made to identify the critical factors governing the engineering behavior of cement-stabilized clay, which helps not only to control the input of cementing agent to attain strength development with curing time and clay water content, but also to understand the subsequent engineering behavior. It is revealed that the clay-water/cement ratio, $wc/ c$ is the prime parameter for the above purposes .

Engineering Behavior of Cement Stabilized Clay at High Water Content (IS-YOKOHAMA 2000「沿岸域の地盤工学における理論と実際」特集号〔英文〕)

Volume Change of Clays Induced by Heating as Observed in Consolidation Tests

Oedometer tests starting from a very small effective vertical stress of 0·5 kPa were performed on three reconstituted clays with different liquid limits The soils were prepared at various initial water contents, ranging from 0·7 to 2·0 times their corresponding liquid limits It is observed that the e–log σ ′ v compression curves show an inverse ‘S' shape due to suction pressure resisting deformation, similar to that of soft natural clays caused by consolidation yield stress The suction pressure σ ′ s of the reconstituted clays can be correlated with the ratio of initial void ratio to void ratio at liquid limit e0/eL The suction pressure curve defined by a unique relationship between suction pressure σ ′ s and the normalised void ratio at suction pressure es/eL is also proposed to distinguish between the pre-suction and the post-suction states In addition, Burland's concept of the intrinsic compression line is adopted for correlating the compression curves of various reconstituted clays at high initia

/pdf/compression-behaviour-of-reconstituted-soils-at-high-initial-5bwcn4awu4.pdf

Compression Behaviour of Reconstituted Soils at High Initial Water Contents

This paper proposes a simple, practical method of three‐dimensional stability analysis for concave slopes in plan view using the equilibrium concept. The force equilibrium and the moment equilibrium conditions over failure mass are satisfied in the analysis. The results obtained using this three‐dimensional method show that the stability of concave slopes in plan view increases as the relative curvature radii R0/H0 decrease, and the influence of plan curvature on the stability of concave slopes in plan view changes when the lateral pressure coefficient of soil Ka is different. When the ratio R0/H0 is relatively small, the slip surface passes not through the toes of concave slopes in plan view, but above them. Finally the results obtained through this three‐dimensional method for a straight slope under six different conditions are compared with the results calculated through six two‐dimensional methods.

Closure of "Three-Dimensional Stability Analysis of Concave Slopes in Plan View"

The intercept of the log(1+e)–logσ ′ v straight line is introduced to describe the effect of the starting point on the compressibility of natural and reconstituted clays. It is found that when the effective stress exceeds the remoulded yield stress, the compression behaviour of reconstituted clays is controlled solely by the water content at the remoulded yield stress and the liquid limit. Comparison of the compression behaviour of natural and reconstituted clays indicates that their difference in compressibility is caused by soil structure and the difference in water content at the compression starting point. The compression behaviour of natural clays can be classified into three regimes: (a) the pre-yield regime, characterised by small compressibility, with soil structure restraining the deformation up to the consolidation yield stress; (b) the transitional regime, characterised by a gradual loss of soil structure when the effective stress is between the consolidation yield stress and the transitional s...

/pdf/compression-behaviour-of-natural-and-reconstituted-clays-3ffrzmi21a.pdf

Compression behaviour of natural and reconstituted clays

https://www.jstage.jst.go.jp/article/sandf1995/41/5/41_5_129/_pdf

Practices of reused dredgings by cement treatment

Engineering behavior of cement-treated marine dredged clay during early and later stages of curing

https://www.jstage.jst.go.jp/article/sandf1995/36/2/36_2_57/_pdf

Comparative study on sample quality using several types of samplers

Strength and stiffness of cement-treated marine dredged clay at various curing stages

The lack of construction materials in the coastal areas and the high cost of importing good-quality soil creates the need for developing new technologies to manufacture engineered fills using low-quality materials obtained from a seabed. This study presents results of a series of tests conducted to obtain field data related to basic engineering properties of a geomaterial comprised of the mud dredged from Tokyo Bay, mixed with lightweight additives, such a foam or expanded polystyrol beads, and portland cement as a binder. Due to discrepancies that may exist in laboratory-prepared samples, a field study was launched to replicate the actual construction conditions. Relationships are developed to correlate various engineering properties of the geomaterial in terms of strength, modulus of elasticity, and deformation characteristics.

Takashi Tsuchida

Papers

Practices of reused dredgings by cement treatment

Engineering behavior of cement-treated marine dredged clay during early and later stages of curing

Comparative study on sample quality using several types of samplers

Strength and stiffness of cement-treated marine dredged clay at various curing stages

Development of a Geomaterial from Dredged Bay Mud