Constitutive Modeling of Coal Ash Using Modified Cam Clay Model

Previous studies showed that the addition of coconut shell ash (CSA) to soil improved the California Bearing Ratio, Maximum Dry Density, and Unconfined Compressive Strength. But the effect of CSA in decreasing soil susceptibility to static liquefaction has yet to be investigated. Static liquefaction is a major concern because it is defined as when soil loses its strength and behaves like a fluid. This causes settlements, damages buildings, and endangers lives. The loss in soil strength is attributed to the increase in pore water pressure. Pore water pressure buildup is more likely to happen in loose and saturated sands. This study hypothesizes that the particle size and the chemical property of CSA can reduce the liquefaction susceptibility of sands by decreasing pore water pressure buildup when the sand is subjected to vertical loads. For the experiment, the consolidated undrained (CU) triaxial test was conducted. The Cam-Clay model was used to analyze soil behavior between the control samples and the samples mixed with CSA. Results show that administering 5 % CSA expanded the soil's yield surface, improving soil's ability to respond elastically to deformations. Five percent CSA decreased pore water pressure buildup in the samples subjected to 50 kPa and 100 kPa consolidating pressures by 6.53 % and 5.55 %, respectively. However, for the sample subjected to 25 kPa consolidating pressure, 5 % CSA caused an adverse effect by increasing pore water pressure buildup by 10.73 %. The low consolidating pressure negates the effect of CSA and there should be a sufficiently high consolidating pressure to decrease pore water pressure buildup.

Section: Cam-clay Modelmentioning

confidence: 99%

Effect of Coconut Shell Ash on Pore Water Pressure Changes in Sand

Lim¹

2022

“…Many models may also be considered [20,21,22,23]. In the study, their permeability values were used to generate linear optimization model.…”

Section: Linear Optimization Modelmentioning

confidence: 99%

Linear Optimization of Soil Mixes in the Design of Vertical Cut-Off Walls

Dungca¹,

Galupino²,

Sy³

et al. 2018

ABSTRACT:In order to prevent the contamination of surrounding groundwater in a landfill, cut-off walls were recommended. Cut-off walls are walls utilized when there is a need to restrict horizontal movement of liquids. Currently, the factors in designing cut-off walls are effective permeability, and relatively inexpensive materials in containing contaminants. It was suggested to provide a mix of 96% soil and 4% bentonite in the design of cut-off walls, but bentonite is relatively expensive, thus the viability of fly ash as a replacement for bentonite was considered. Soil mixtures were proposed and rigorous laboratory tests was performed to determine the individual properties. Tests such as specific gravity tests, Atterberg limit tests (liquid limit, plastic limit and plasticity index), emax and emin test/relative density tests, particle size analyses, microscopic characterizations, elemental composition tests and permeability tests were performed to garner data, and were utilized for the model. A linear optimization model was generated to achieve the least cost with the minimum required permeability. The minimum permeability requirement for the cut-off wall was achieved by providing various mixtures for soil-bentonite-fly ash.

“…Many models may be considered in the study [15,16,17,18]. The experiments conducted for the different blends had been reasonably included within its limits which is 10 -6 < k <10 -3 for sand and sandy soils.…”

Section: Modelmentioning

confidence: 99%

Hydraulic Conductivity Characteristics of Road Base Materials Blended With Fly Ash and Bottom Ash

Dungca¹

2018

Hydraulic conductivity, is the ability of water to flow through a soil, should be considered when designing roads. Hydraulic conductivity should be employed when designing roads that will provide good drainage as well. Fly ash and bottom ash were utilized as partial substitutes to conventional road base materials in road base construction. The study aimed to prove that employing fly ash and bottom ash would increase the hydraulic conductivity characteristics of road base while also decreasing the disposal costs of the said coal by-products. Series of experiments were conducted to test the horizontal and vertical hydraulic conductivity of pure fly ash, pure bottom ash, pure conventional road base materials, and blends comprising of the said soil components. It was also established that horizontal and vertical hydraulic conductivity had a significant difference wherein the flow of water at the horizontal-direction is greater compared to the vertical-direction.