Abstract
The newly developed three-dimensional finite element program was applied to the problem of the stress and deformation of the reclaimed marine deposits for the connecting bridge at the corner of the Kansai International Airport (KIX) fill. The connecting bridge of KIX is supported by the sea friction piles and the abutment on the airport fill. Differential deformation has been expected to occur at the border of the pile foundation and abutment on the reclaimed fill. Then, for the corner of the large reclaimed island, a three-dimensional analysis is strongly required because a stress dispersion with depth for the applied filling load is expected to occur, and one and two-dimensional approaches have a definite limitation to assess the stress and deformation due to reclamation. Stress dispersion was remarkable with depth. The stress concentration effect due to the existence of a deeply compacted sand column in the alluvial clay layer influenced the subsequent deformation of the Pleistocene deposits. Remarkable lateral displacement, as a typical three-dimensional behavior, was observed in association with long-term settlement. It is noteworthy that the in-situ measured settlement is found to be well described with the calculated performance by the developed 3D elasto-viscoplastic finite element program.
Key Words
elasto-viscoplastic constitutive model; Kansai International Airport (KIX); reclaimed marine foundation; stress dispersion
Address
Seong-Kyu Yun, Hyeonsu Yun and Gichun Kang: Department of Civil Engineering, College of Engineering, Gyeongsang National University, 501 Jinjudae-ro,
Jinju, Gyeongsangn,-do 52828, Republic of Korea
Abstract
Highly organic soils are often challenging for geotechnical applications due to their low strength, high
compressibility, and increased permeability. This study investigates the efficacy of xanthan gum (XG) biopolymer as an ecofriendly
alternative to traditional, carbon-intensive soil stabilizers. A comprehensive series of laboratory experiments was
conducted to assess the effects of XG on the compaction behavior, unconfined compressive strength (UCS), elastic modulus
(E₅₀), and permeability of organic soils. XG dosages ranged from 0% to 5% (by dry weight of soil), with aging periods extending
up to 60 days. The test results demonstrate that 1% XG significantly improves the mechanical properties of the soil, achieving a
sixfold increase in UCS and E₅₀ greater than 20,000 kPa within 28 days of aging. Additionally, permeability was reduced by 3–5
orders of magnitude, meeting the stringent requirements for hydraulic barrier applications. Scanning electron microscopy (SEM)
identified the formation of a bridging gel matrix and associated pore-clogging as the key microstructural mechanisms
responsible for the significant gains in strength and the drastic reduction in permeability. Based on the analysis of strength,
stiffness, and permeability, 1% XG was identified as the optimal dosage. These findings highlight the significant potential of XG
as a sustainable, cost-effective solution for stabilizing highly organic soils, offering substantial performance enhancement while
maintaining environmental benefits. XG presents a viable alternative to conventional stabilizers in geotechnical applications,
particularly in projects requiring environmentally conscious and efficient material solutions.
Address
Muhammad Hamza: College of Civil and Transportation Engineering, Shenzhen University, Shenzhen 518060, China;
State Key Laboratory of Intelligent Geotechnics and Tunnelling, Shenzhen University, Shenzhen 518060, China
Muhammad Israr Khan: College of Civil and Transportation Engineering, Shenzhen University, Shenzhen 518060, China;
State Key Laboratory of Intelligent Geotechnics and Tunnelling, Shenzhen University, Shenzhen 518060, China;
Key Laboratory for Resilient Infrastructures of Coastal Cities, Shenzhen University, Shenzhen 518060, China
Abstract
In highway engineering, foamed concrete used for subgrade filler is typically influenced by external environmental
factors such as freeze-thaw cycles and vehicle loads. This study conducts freeze-thaw cycle tests, load cycle tests, and coupling
(freeze-thaw-load) cycle tests under the designed wet density to simulate the field environment of highway engineering and
examine the strength variation of foamed concrete under different conditions. Additionally, the pore structure and freezing
damage mechanism of foamed concrete were analyzed using SEM. The results indicate that the strength loss of foamed concrete
exceeds 20% after 100 freeze-thaw cycles. During the load cycle tests, the compressive strength of foamed concrete can be
divided into three stages, corresponding to the development of micro-cracks in the material. In the coupled environment to
simulate field conditions, the compressive strength of foamed concrete decreases rapidly to 0.96 MPa (20.66% loss) after the
first 10 years, which followed by a slower decline (0.83 MPa in the 20th years and 0.78 MPa in the 40th years). SEM analysis
shows that the internal damage caused by freeze–thaw cycles can be categorized into cavity failure and crack failure.
Key Words
coupling cycles; foamed concrete; freeze-thaw cycles; load cycles; SEM analysis
Address
Long Chen, Yi Zhu and Desheng Li: College of Civil and Transportation Engineering, Hohai Univ., Nanjing, Jiangsu 210098, China
Lunyang Zhao: School of Civil Engineering and Transportation, South China Univ. of Tech., Guangzhou, Guangdong 510641, China
Yonghui Chen: Suzhou Research Inst. of Hohai Univ., Suzhou, Jiangsu 215004, China
Ming Huang: The Fourth Construction Co., Ltd of China Railway Construction Engineering Group, Shanghai 201306, China
Abstract
The hyperbolic method is a method of predicting the future settlement from the measured settlement based on the assumption that the speed of settlement decreases in the form of a hyperbola over time. However, this method forces artificial linearity during linear regression analysis because both the independent variable (time) and dependent variables (time/settlement) contain time. Thus, to overcome this problem, this study proposed the nonlinear and weighted nonlinear regression hyperbolic methods to supplement the statistical incompleteness of the original hyperbolic method based on linear regression. A hyperbolic method that applied nonlinear regression analysis and a weighted nonlinear regression hyperbolic method that applied high weight linearly over time were proposed as alternatives to the existing linear regression hyperbolic method. The accuracies of the original, nonlinear, and weighted nonlinear regression hyperbolic methods were analyzed and compared based on the time-settlement data measured from six sites with thick soft clay layers in Busan new port. The proposed methods yielded superior results compared to the original hyperbolic method. Further research on the forms of various weight functions can lead to the formulation of an optimal weighted nonlinear regression hyperbolic method.
Key Words
consolidation; field monitoring; regression; settlement prediction; soft clay site
Address
Tae Young Kwak, Seongho Hong and Ju Hyung Lee: Department of Geotechnical Engineering Research, Korea Institute of Civil Engineering and Building Technology, Goyang, South Korea
Sang Inn Woo: Department of Civil and Environmental Engineering, Incheon National University, Incheon, South Korea
Abstract
The conventional uniformity coefficient Cu fails to capture the uniformity of gap-graded granular mixtures. To
address this limitation, this study introduces a new index Cu
m for quantifying mixture uniformity based on their small-strain
stiffness G0. Granular mixtures with varying fines content (FC) and particle size ratio (PSR) were prepared, and their G0 values
were determined through quasistatic drained triaxial tests. The corresponding Cu
m values were then derived from the measured
G0 values and expressed as a function of FC and PSR. The rationality of the proposed Cu
m was verified, and it was further
demonstrated that Cu
m can be used to predict the small-strain stiffness of granular mixtures when the mechanical coordination
number (CNm), particle shear modulus of particles (Gp), confining stress (O0) and Cu
m are known.
Key Words
DEM; fines content; granular mixtures; particle size ratio; small-strain stiffness; uniformity coefficient
Address
Jian Gong, Jingwen Xu, Dianhong Huang and Yu Tang: School of Civil Engineering and Architecture, Guangxi University, Nanning, Guangxi 530004, China
Zhiyong Liu: Shanghai Key Laboratory of Rail Infrastructure Durability and System Safety, Tongji University, Shanghai 201804, China
Abstract
Particle breakage can alter the gradation of soil, reduce the interparticle contact friction induced by shear, and serve as
a primary cause of deformation in geomaterials, significantly influencing their engineering mechanical properties. The singleparticle
crushing test is an essential test method for investigating particle breakage and strength. However, merely analyzing
particle strength neglects the deformation information during the crushing process, leading to an inability to accurately
characterize the strain state before the particle's overall breakage. In this study, single-particle crushing tests were designed and
conducted to analyze the particle strength and specific fracture energy of limestone particles. Based on the analytical results, an
equivalent stiffness was formulated. By introducing the concept of equivalent stiffness, the distribution of specific fracture
energy was transformed into a particle strength distribution. The validity and reliability of this conversion method were verified,
demonstrating its effectiveness in statistically characterizing different stress-path features of particles. This study reveals that the
equivalent stiffness of 10-20 mm Baihetan limestone particles in single-particle crushing test is 4.7x106N/m. This result offers a
reference value for associated numerical modeling and can inform the corresponding engineering design.
Key Words
equivalent stiffness; particle strength; single-particle crushing test; specific fracture energy
Address
Buxueyan Wang: Department of Geotechnical Engineering, Tongji University, Shanghai, 200092, China
Zhiyong Liu: Shanghai Key Laboratory of Rail Infrastructure Durability and System Safety, Tongji University, Shanghai, 201804, China
Jiangu Qian: Department of Geotechnical Engineering, Tongji University, Shanghai, 200092, China;
State Key Laboratory of Disaster Reduction in Civil Engineering, Tongji University, Shanghai, 200092, China
Ilhan Chang: Department of Civil Systems Engineering, Ajou University, Suwon-si, 16499, Republic of Korea
