Abstract
As a new type of high-speed railway subgrade filler, the deformation performance of foamed concrete under longterm
traffic loading requires further research. In addition, the potential adverse effects caused by water immersion in actual
environments cannot be overlooked. In this paper, a series of dynamic triaxial tests were performed to study the deformation
behavior of foamed concrete samples under dry and water immersion conditions, considering the effect of dynamic stress
amplitudes and confining pressures. Moreover, scanning electron microscopy was used to capture the microstructure
characteristics of the foamed concrete. The pore shape coefficient and fractal dimension were introduced to explain the
macroscopic deformation properties. For the dry sample subjected to dynamic loading, its resistance to deformation increases
with increasing buried depth. However, the previous water immersion treatment led to the pore structure of the foamed concrete
being more vulnerable to damage under subsequent dynamic loading. At this time, the accumulative deformation of the wet
samples was greater than that of the dry samples, especially at the top and bottom layers. Notably, as the dynamic stress
amplitude exceeded 20 kPa, a rapid growth of the accumulative deformation was observed for the samples. In addition, the pore
structure characteristics of the foamed concrete under the excitation of dynamic loading experience significant variation, with
the large pores splitting into small pores and the pore diameter decreasing. The pore walls of the large pores ruptured and
connected with others, accompanied by an increase in the number of narrow pores. The findings in this paper contribute to a
better understanding of the design and maintenance of the foamed concrete subgrade.
Key Words
accumulative strain; dynamic loading; foamed concrete; fractal dimension; pore structure; water immersion
conditions
Address
Long-Ji Zhang, Zhen-Dong Cui, Yan-Kun Zhang and Mukhtiar Ali Soomro: State Key Laboratory of Intelligent Construction and Healthy Operation & Maintenance of Deep Underground Engineering,
School of Mechanics and Civil Engineering, China University of Mining and Technology, Xuzhou, Jiangsu 221116, PR China
Abstract
Studies on uplift piles in layered soil have been insufficient. This study aimed to develop an analytical model to
predict the limit state performance of single pile in two-layered soil under uplift load. Appropriate mathematical correlations
have been derived for uplift capacity and limiting displacement of piles considering limit state analysis. Validation of the model
by comparison with available experimental and theoretical results ensured its accuracy. The model has been applied to conduct
parametric studies and develop design curves for uplift pile design considering safety and serviceability criteria. A typical design
example has also been illustrated. From the entire study, relevant conclusions are drawn.
Key Words
cohesionless soil; cohesive soil; layered soil; single pile; uplift load
Address
Sudip Basack: Principal, Regent Education and Research Foundation, Affiliated: MAKA University of Technology, Kolkata, India;
Department of Civil Engineering, Graphic Era Deemed to be University, Dehradun, Uttarakhand, India
Meshel Q. Alkahtani and Saiful Islam: Department of Civil Engineering, College of Engineering, King Khalid University, Abha, Saudi Arabia
Abstract
Portland cement, a conventional binder for soft soil stabilization, faces limitations in treating specialized soils due to
its high carbon footprint and environmental impact during production. This study proposed an eco-friendly alternative using
reactive magnesia (MgO) and magnesium chloride (MgCl2) for carbonation treatment of saline soft soils. The mechanical
properties, hydrochemical behavior, water stability, and microstructural evolution of carbonation-stabilized soils were
systematically investigated under varying salinity levels (MgCl2 content) and initial moisture conditions. Key findings revealed
that unconfined compressive strength and modulus decreased with increasing initial water content but exhibited a unique trend
under MgCl2 variation—initial gradual reduction (3–6% MgCl2) followed by significant enhancement (6–12% MgCl2).
Carbonation efficiency declined from 40% to 10% with rising initial water content, while showing a V-shaped relationship with
MgCl2 dosage (minimum at 6%). Post-carbonation pH decreased with higher MgCl2 content and lower initial moisture, whereas
electrical conductivity increased proportionally to both parameters. Microstructural analyses identified distinct phase formations:
low-MgCl2 (6%) systems produced flower-like hydromagnesite, spheroidal dypingite, and prismatic nesquehonite, while high-
MgCl2 (12%) systems generated short-rod chloro-carbonates and acicular magnesium oxychloride crystals
(5Mg(OH)2 MgCl2 8H2O). These crystalline phases collectively enhanced soil stabilization. Optimized performance was
achieved at a magnesium-chloride molar ratio <6 and a water-chloride ratio of 12–17, demonstrating the viability of MgOMgCl2
carbonation activation for sustainable soil stabilization.
Address
Guanghua Cai, Yibo Wang and Han Zhang: College of Civil and Engineering, Nanjing Forestry University, Nanjing 210037, China
Zhaoyuan Guo: School of Transportation, Southeast University, Nanjing 211189, China;
Jiangsu Provincial Transportation Engineering Construction Bureau, Nanjing 210004, China
Tianyun Liu: Tianjin Port Engineering Institute Ltd. of CCCC First Harbor Engineering Company Ltd., Tianjin 300222, China
Hongsen Liu: Yellow River Engineering Consulting Co., LTD, Zhengzhou 450003, China
Chi-Sun Poon: Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong
Abstract
In recent years, tunnel-type anchorage (TTA) has been increasingly applied in long-span suspension bridges.
However, research on its reliability analysis under seismic effects remains insufficient. This study takes the Puli Bridge in
Yunnan Province, China, as an example to investigate the dynamic response and reliability of the TTA of a suspension bridge
under seismic action. The dynamic response of ten measurement points on the front and rear anchor faces of TTA under seismic
acceleration was calculated and analyzed using finite difference method software. Combining the secondary sequence response
surface method, the reliability indices of each measurement point on the anchor surface before and after TTA were calculated
and analyzed, and the limit state equation of TTA dynamic response was established. The results indicate that the elastic
modulus and cohesion of the TTA surrounding rock have a significant influence on the dynamic response of the TTA. The
dynamic response of TTA decreases with increasing elastic modulus and increases with increasing cohesion. As shown in its
displacement response. Due to the design characteristics of TTA, the reliability value of the front anchor surface is significantly
lower than that of the rear anchor surface. Under different peak ground accelerations (PGA), the reliability of different crosssections
of TTA varies and decreases with increasing PGA, indicating that the reliability of TTA is highly sensitive to changes in
PGA. Research on the dynamic response and reliability of the front and rear anchor surfaces of TTA structures can provide
reference and assistance for the seismic retrofitting and optimization design of TTA structures.
Key Words
bridge and tunnel engineering; dynamic response; ground motion acceleration; reliability analysis; tunneltype
anchorage
Address
Guojun Yang, Shutao Zhang and Yongfeng Du: Western Engineering Research Center of Disaster Mitigation in Civil Engineering of the Ministry of Education,
Lanzhou University of Technology, Lanzhou 730050, China
Guangwu Tang: State Key Laboratory of Bridge Engineering Structural Dynamic,China Merchants Chongqing Communications
Technology Research & Design Institute Co., Ltd. Chongqing,400067,China
Abstract
This paper aims to perform a stability analysis of an existing grain bin project based on the 2018 Turkish Building
Earthquake Code (TBEC), and to achieve soil improvement and reinforcement solutions using unreinforced bored piles. In the
study area, after the construction of the grain bins, static loading was applied, and soil problems were observed in certain
sections. As a result, some grain bins were partially taken out of use. To diagnose the problem and understand the soil
stratigraphy, eight (8) boreholes were drilled in the study area. The results indicated that the soil was exposed to surface water,
which caused settlement problems. To solve this problem, the soil was improved by supporting it with unreinforced piles. The
grain bins with capacities of 28000 kN for wheat and 24000 kN for barley, consisting of 18 storage cells with a diameter of 14 m
each, located in Sarioğlan district, Kayseri city, Turkey, were investigated in this paper. The observations of differential
settlement and heave as geotechnical problems started after two of these grain bins were loaded twice with approximately 15000
kN. The extensive laboratory and field tests revealed that the soil consisted of vegetative soil, alluvial soil of various thicknesses
and sandstone, in addition to the fact that the study area is close to an active fault. Bearing capacity and horizontal slip were
checked according to TBEC (2018), and settlement analyses were carried out using PLAXIS 2D and 3D to identify the
mechanical characteristics of the grain bins that have differential settlement problems in the field. The amount of settlement
occurring in the existing condition was determined to be approximately s0=47 mm. In the case of ground improvement and
reinforcement, the maximum total settlement was found to be s1=23 mm, the maximum differential settlement s=0.21 mm,
and the angular distortion =0.0015%. As a result of the investigations, it was understood that there was no bearing capacity
and horizontal slip failure, and the numerical analyses indicated that the use of unreinforced bored piles with controlled
embankment brought the settlement and angular distortion to permissible limits.
Address
Osman Sivrikaya, Burak Akçay, Fatih Yesevi Okur,
Süleyman Adanur and Ahmet Can Altunişik: Department of Civil Engineering, Karadeniz Technical University, 61080 Trabzon, Turkey
Firdevs Uysal: Department of Civil Engineering, Niğde Ömer Halisdemir University, 51240 Niğde, Turkey
Abstract
This study integrates machine learning (ML) algorithms and system reliability analysis to assess the stability of
geotextile-reinforced retaining walls. The research utilized ensemble-based ML techniques such as Random Forest (RF),
Gradient Boosting (GBM), and Extreme Gradient Boosting (XGB), alongside the First-Order Second Moment (FOSM) method,
the study evaluates multiple failure scenarios sliding, overturning, bearing capacity, rupture, and pullout with soil parameters
treated as random and geometric parameters as deterministic. Results indicate that RF and GBM outperform XGB, achieving R2 accuracy, while XGB exhibits variability, particularly in sliding and rupture conditions, suggesting sensitivity to data
distribution. Lower RMSE and RSR values for RF and GBM confirm minimal errors, while a Willmott Index (WI) above 0.99
reflects strong agreement between predicted and actual values. The Bias Factor remains close to 1.0, ensuring unbiased
estimations, while low TIC and sMAPE values highlight superior generalization between training and testing datasets. System
reliability analysis reveals a system reliability index (B𝑠𝑦𝑠𝑡𝑒𝑚 = 1.083), lower than the minimum component reliability index
(B𝑚𝑖𝑛 = 1.213) from FOSM, emphasizing the need for a comprehensive probabilistic assessment. The study demonstrates that
machine learning, particularly GBM and RF, provides robust predictions, improving the reliability evaluation of reinforced
retaining walls.
Key Words
GBM; retaining wall; RF; sequential compounding method; system reliability; XGB
Address
Pratima Kumari, Pijush Samui and Avijit Burman: Department of Civil Engineering, National Institute of Technology Patna, Patna, Bihar 800005, India
