Utilisation of ground granulated blast furnace slag (GGBFS) for soft soil improvement by deep mixing method

Ground granulated blast furnace slag (GGBFS) is the by-products from pig iron plants which can cause a serious problem for land, soil, and water. Thus, the study for reusing GGBFS is very nessesary. This paper presents the utilisation of GGBFS for soft soil improvement by cement deep mixing method. Portland cement was replaced by GGBFS from 0 to 100% and a total of 33 specimens were used to determine the unconfined compressive strength and deformation modulus of treated soil. The experimental results showed that replacement of GGBFS from 0 to 60% cement could increase the unconfined compressive strength and deformation modulus of treated soil. The optimum GGBFS content was found to be 30% of cement content. In general, the utilisation of GGBFS for soil improvement could increase the properies of soft soil and soil treated with cement. The result of this study will be basic for utilisation of GGBFS in ground improvement by cement deep mixing method.

FIELD TRIALS ON THE SOIL CEMENT MIXING TECHNOLOGY TO REINFORCE EARTH LEVEES IN THE MEKONG DELTA, VIETNAM

The effectiveness of seepage cutoff and sliding stability of an earth levee reinforced by soil cement deep mixing technology (SCDM) was evaluated by field monitored data. Groundwater observation was conducted via nine ground water wells installed in the research site. Lateral displacement of the whole earth levee was measured by the 15-m inclinometer casing and a 0.5-m inclinometer probe. The research assessed effects of soilcrete reinforcement by comparing with simulations before applying widely in the Mekong Delta, Vietnam. The results indicate that the soilcrete walls can effectively prevent the seepage through the earth levee’s body and improve the factor of safety about 1.2 times.

Comparisons and Decisions on Construction Methods from an Energy Consumption and Carbon Emission Perspective

This paper established a evaluation model of construction methods aiming at the key indexes including energy consumption, carbon emission and cost. The model disassembles the energy consumption and carbon emission into four parts, i.e. labor, material, transportation, and manufacture construction. The corresponding module calculation method is proposed. A calculation example is presented. It is about a comparison among five typical foundation treatments. With this evaluation model, the performance ranking is yielded, which is cement-flyash-gravle pile, vibroflotation, high-pressure jet grouting, cement deep mixing, sand-gravle pile.

Numerical Simulation of Load Transfer Mechanism of T-Shaped Soil-Cement Deep Mixing Column

T-shaped soil-cement deep mixing column load transfer mechanism is different from the general section column. Basing on the fast Lagrangian finite difference method, we study the load transfer mechanism of T-shaped soil-cement deep mixing column at different load levels, expanding head height and the ratio of upper and lower pile diameter. By the numerical simulation we obtained that the axial force plummeted value of expanding head flange increases with the load and the ratio of upper and lower pile diameter increasing, it will decreases when the height of expanding head increasing.This paper can provide a reference for the design of T-shaped soil-cement deep mixing column.

Analysis on Consolidation and Settlement Characteristics of Composite Foundation with T-Shaped Bidirectional Soil-Cement Deep Mixing Columns

Based on the solution of one-dimensional consolidation model of T-shaped bidirectional soil-cement deep mixing column composite foundation and its calculating program deduced by the separation of variables and Laplace method. This paper discussed the consolidation and settlement characteristics of composite foundation under the conditions of different loading modes, foundation reinforcement modes, diameter of enlarged pile head and pile spacing. The results indicate, the soil layer in the region of enlarged pile head hardly be influenced by above factors, the lower soil layer and soft substratum soil are influenced greatly. Loading mode has a large effect on the consolidation, when loading instantaneously, the rate of consolidation is faster than that of loading constantly. The consolidation and settlement behavior of composite foundation reinforced by T-shaped bidirectional soil-cement deep mixing column and traditional bidirectional deep mixing column is much better than the original natural foundation. When the other parameters stay the same, consolidation degree and total settlement decrease with the increase of enlarged pile head diameter. With the increase of pile spacing, consolidation rate of the composite foundation decreases significantly, but the settlement value increases rapidly on the contrary.

Study on the Scope of Application of Cement Deep Mixing Pile to Consolidate Soft Soils

According to the experiments study, the formulas of strength with the changes of moisture content, natural dry density, cement dosage are presented. Applicable range of cement mixing pile to consolidate soft soils is determined which can be used to guide the using of cement mixing pile and provide reference for design or research departments at the same time.