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RISS 인기검색어
- 검색키워드
- 저자 : Sanjay Nimbalkar (검색결과 4 건)
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Free strain analysis of the performance of vertical drains for soft soil improvement
Basack, Sudip,Nimbalkar, Sanjay Techno-Press 2017 Geomechanics & engineering Vol.13 No.6
Improvement of soft clay deposit by preloading with vertical drains is one of the most popular techniques followed worldwide. These drains accelerate the rate of consolidation by shortening the drainage path. Although the analytical and numerical solutions available are mostly based on equal strain hypothesis, the adoption of free strain analysis is more realistic because of the flexible nature of the imposed surcharge loading, especially for the embankment loading used for transport infrastructure. In this paper, a numerical model has been developed based on free strain hypothesis for understanding the behaviour of soft ground improvement by vertical drain with preloading. The unit cell analogy is used and the effect of smear has been incorporated. The model has been validated by comparing with available field test results and thereafter, a hypothetical case study is done using the available field data for soft clay deposit existing in the eastern part of Australia and important conclusions are drawn therefrom.
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Strength and Deformation Characteristics of Calcareous Sands Improved by PFA
Qing-Sheng Chen,Wan Peng,Gao-LiangTao,Sanjay Nimbalkar 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.1
Calcareous sand is widely distributed in the islands of the South China Sea, which could be promisingly used as the construction materials. However, particle breakage commonly occurs in calcareous sands, which may significantly influence their mechanical characteristics. To address these issues, an eco-friendly agent, i.e., polyurethane foam adhesive (PFA) is proposed to improve the engineering properties of calcareous sands, compared to the commonly used alkaline stabilizing agents (e.g., lime, cement). The objective of this work is to examine the effectiveness of using PFA in improving the strength-deformation properties of calcareous sand. A series of laboratory tests including direct shear tests, unconfined compression tests, and oedometer tests were performed on the calcareous sands improved by PFA. In addition, A scanning electron microscope (SEM) was conducted to reveal microstructural analysis of using PFA for calcareous sand. The experimental results provided insights into the shear strength, deformation modulus, as well as the micro-structural characteristics of improved calcareous sands with various PFA contents and particle size distributions.
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Qing-Sheng Chen,Hongyu Zhang,Jianjun Ye,Gao-LiangTao,Sanjay Nimbalkar 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.4
Cemented soil structures are frequently exposed to the corrosive environment of seawater for an extended period, severely affecting their interior structure and mechanical qualities. This study presents laboratory-based approach to investigate the effect of nano-SiO2 on the structural and mechanical properties of cemented soil in a simulated seawater environment. The unconfined compressive strength (UCS), elastic modulus and other mechanical properties of cemented soil mixed with nano-SiO2 and ordinary silicate cemented soil were evaluated. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to deduce the crystalline composition and microstructure characteristics of the modified cemented soil. The results show that the addition of nano-SiO2 greatly increased the compressive strength and corrosion resistance of the cemented soil. In a 3C (105% salinity) simulated saltwater curing environment, the compressive strength of the cemented soil containing 2% nano-SiO2increased by 86% and 158% at 30days and 60days, respectively. XRD and SEM showed that nano-SiO2 enhanced the interface structure of cemented soil and increased the compactness of the cement-soil system. The current study demonstrates that nano-SiO2 could considerably improve the mechanical characteristics and corrosion resistance of cemented soil when exposed to simulated seawater.
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Permeability and cracking of compacted clay liner improved by Nano-SiO2 and sisal fiber
Gao-LiangTao,Erhui Guo,Jinghan Yuan,Qing-Sheng Chen,Sanjay Nimbalkar 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.12
The landfill liner is the last line of defense to protect the soil from damage, but it is difficult to satisfy both impermeability and crack resistance requirements with conventionally compacted clay. This paper proposes a new composite material to enhance the anti-seepage and anti-cracking properties of clay as a solution to this problem. In this Study, the effects of two single amendment materials, Nano-SiO2 (6 dopings) and sisal fiber (SF) (4 dopings), and a composite amendment material (Nano-SiO2+SF), on the permeability and cracking resistance of the improved clay were investigated by infiltration tests and dry-wet cycle tests, respectively. The nuclear magnetic resonance test (NMR) test reveals the microscopic pore changes of soil and explore the reinforcement mechanism. The findings of penetration experiments demonstrate that Nano-SiO2 and SF, both single and composite components, can increase the modified clay's impermeability. The optimum content of Nano-SiO2 is 3%, and its permeability coefficient is 5.09 × 10−8 cm·s−1, which is two orders of magnitude lesser than that of virgin soil. The results of three dry and wet cycle tests showed that the overall trend of fracture length and cracking factor (CIF) increased with the increase of the number of de-wetting. After the third de-wetting of the modified clay, 0.75% Nano-SiO2 + 0.3% SF is the optimal dose, which reduces the fissure length by 19.94 times and CIF by 27.25 times compared with the three de-wetting of the plain clay. As a whole, the data demonstrates that the composite Nano-SiO2 and SF are able to make up for the shortcomings of each component. It can simultaneously improve the anti-seepage and anti-cracking properties of the enhanced clay. The test results provide a certain benchmark for the impermeability and anti-cracking of landfill liners.
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