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CONTENTS
Volume 39, Number 4, November25 2024
 

Abstract
The issue of problematic disposal of excavated material, commonly referred to as muck, generated during tunnel boring machine (TBM) excavation has emerged as an environmental challenge amidst the escalating demand for sustainable engineering solutions. TBM excavation operations necessitate the use of a slurry to bolster the excavation process and aid in muck conveyance. Typically composed of bentonite, this TBM slurry is conventionally discarded along with the excavated spoils, posing risks to human safety and raising environmental contamination apprehensions. This study aims to explore a novel slurry material as a means to mitigate the toxicity associated with muck disposal. Given the notable adsorption capabilities of bentonite, alternative options such as kaolinite clay and xanthan gum biopolymer are under consideration. Through experimental analysis, various combinations of bentonite clay, kaolinite clay, and xanthan gum are examined to assess their effectiveness in enhancing tunneling performance and optimizing transport properties. The evaluated parameters encompass rheological characteristics, swelling behavior, permeability, suspended viscosity and stickiness. Employing statistical analysis integrated with random weighting factors and the measured properties of each slurry candidate, competitiveness of each slurry candidate is analyzed. The findings of this investigation, accounting for 47.31% priority across all probabilistic scenarios, indicate that a specific blend consisting of bentonite and xanthan gum (2.5% bentonite, 0.75% xanthan gum) demonstrates considerable promise as a substitute for conventional bentonite-based slurries (7.5% bentonite) in TBM excavation applications.

Key Words
biopolymer; biopolymer-based soil treatment (BPST); geotechnical engineering; xanthan gum; slurry

Address
Sojeong Lee: Korea Standard Construction Center, Korea Institute of Civil engineering and Building Technology, Goyang 10223, Korea
Barrie Titulaer: Snowy Hydro, Cooma, NSW, 2630, Australia
Hee-Hwan Ryu: Next generation Transmission and Substation Laboratory, KEPCO Research Institute, Daejeon, 34056, Korea
Ilhan Chang: Department of Civil Systems Engineering, Ajou University, Su-won 16499, Korea

Abstract
The aim of the present investigation is focused on the nonlinear forced vibration analysis of porous FGM sandwich beam with a viscoelastic core resting on nonlinear elastic foundation. The analytical formulation incorporates both normal and shear deformations in the core by utilizing the Zig-Zag theories. The harmonic balance method is integrated with a one-mode Galerkin's procedure designed for a simply supported beam. The nonlinear geometric coupling and viscoelastic effects result in a frequency amplitude equation that is nonlinear and governed by multiple complex coefficients. The damping and frequency response curves are depicted and analyzed across various geometrical and mechanical configurations of sandwich beams. The results indicate that the porosity effects and elastic coefficients of the foundation exert a significant influence on the damping and nonlinear vibration response of these beams.

Key Words
analytical modeling; damping; porosity; FGM; nonlinear elastic foundation; vibration; viscoelastic; Zig-Zag theories

Address
Hadj Youzera: Laboratoire d'Etude des Structures et de Mécanique des Matériaux, Département de Génie Civil,
Faculté des Sciences et de la Technologie, Université Mustapha Stambouli B.P. 305, R.P. 29000 Mascara, Algérie
Abdallah Zine: Department of Civil Engineering, Faculty of Science and Technology, University of Relizane, Algeria
Sid Ahmed Meftah: Laboratoire des Structures et Matériaux Avancés dans le Génie Civil et Travaux Publics,
Université Djillali Liabes, Sidi Bel Abbes, Algérie
Abdelouahed Tounsi: Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Department of Civil Engineering, Algeria;
5Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals,
31261 Dhahran, Eastern Province, Saudi Arabia
Mofareh Hassan Ghazwani and Ali Alnujaie: Mechanical Engineering Department, Faculty of Engineering, Jazan University, P.O. Box 45142, Jazan, Saudi Arabia

Abstract
The pressurized water conditions of goafs weaken the support of remaining coal and rocks, which causes instability, failure, and sudden ground collapse. The impact of pressure-bearing water and CO2 on the tensile properties of residual coal pillars was explored in old goafs. Coal was analyzed using a pressure-water soaking device, electronic scanning microscope, and 3D full-field strain measurement system. Besides, Brazilian splitting tests were performed. The failure characteristics and energy evolution law of the macro-microscopic structure of coal specimens were analyzed under different soaking conditions—desiccation (DC), CO2 soaking (CS), water-CO2 soaking (WCS), and water soaking (WS). The peak stress of coal specimens and time to reach the peak decreased with varying soaking environments. Stress concentration initially occurred at the water end under the WCS condition, indicating that coal specimens deteriorated more under the pressure-bearing WCS condition compared with the CS condition. Fractures of coal specimens exhibited the highest development under the WS condition. Besides, dissolution was observed at the fractures of coal specimens, with severe failure to their internal microstructures. In conclusion, the instability failure of residual coal pillars is significant in studying the old goafs.

Key Words
Brazilian splitting test; mesoscopic analysis; soaking condition; tensile strength of coal rocks; water-CO2 action

Address
Ning Jiang: College of Energy and Mining Engineering, Shandong University of Science and Technology, Qingdao 266590, China;
State Key Laboratory of Mine Disaster Prevention and Control, Shandong University of Science and Technology, Qingdao 266590, China
Quanbao Su: College of Energy and Mining Engineering, Shandong University of Science and Technology, Qingdao 266590, China
Xia Jiang: Yuloka (Shandong) Mining Technology Co., Ltd.,Taian 271000, China
Zhiyou Gao and Tao Lyu: College of Energy and Mining Engineering, Shandong University of Science and Technology, Qingdao 266590, China;
Shandong Geology and Mineral Resources Engineering Group Co., Ltd., Jinan 250013, China
Qingbiao Guo: School of Spatial Informatics and geomatics Engineering, Anhui University of Sciences and Technology, Huainan 232001, China
Shijie Song: College of Geology& Environment, Xi'an University of Science and Technology, Xi'an 710054, China
Ke Lyu: School of Mines, China University of Mining and Technology, Xuzhou, Jiangsu, 221116, China


Abstract
The construction of the shield tunnel results in the deformation of the surrounding soil and the existing pipeline. It is important to analyze the deformation of the existing pipeline during the excavation of the tunnel. Based on the two-stage analysis method, the shear effect of pipeline due to the uneven settlement was considered and the deformation and internal force of existing pipeline due to the tunnel excavation were studied. The theoretical formulas were verified by the in-site monitoring. Compared with the theoretical calculation, the three-dimensional numerical simulation was established to simulate the deformation of the existing pipeline and the ground surface during the tunnelling. The effect of the Poisson' s ratio, the tunnel diameter and the pipeline shading on the deformation of the existing pipeline were further investigated. The results show that the deformation curves of the pipeline and the ground surface conform to the Gaussian distribution, and the position above the axis of the tunnel experiences the maximum. When the excavation surface of tunnel crosses underneath the pipeline, the pipeline and the ground surface experience larger deformation and more subsidence, respectively. A certain amount of uplift is generated for the pipeline and the ground surface at +- 20 m away from the center line of the tunnel. The deformation of existing pipelines is affected by the tunnel excavation within its diameter range. The results can provide a reference for the design and construction of the shield tunnel underpass.

Key Words
existing pipeline; shield tunnel; shielding effect of pipeline; underpass construction; vertical deformation of pipeline

Address
Zhen-Dong Cui, Zhang-Lin Zhu, Xuan-Yu Mi, Li Yuan, Zhong-Liang Zhang and Chen-Yang Zhao: 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, P.R. China

Abstract
With the recent development of satellite, aerial, and remote sensing technologies, it is easy to produce landslide inventory maps over a large area. In this study, the object-based framework was designed to address the limitations inherent in the pixel-based deep learning (DL) methodology. This framework explores the potential of combining Sentinel-2 MultiSpectral Instrument (MSI) satellite imagery and digital elevation models (DEMs) to enhance shallow landslide mapping across diverse terrains comprehensively. The study area for analysis and verification was selected as Jucheon-myeon, Namwon-si, and Jeollabuk-do, where significant large-scale landslides and slope failures occurred in 2020. As a result, the application of this framework led to the classification of 68 candidate sites spanning an area of 0.5 hectares or more. Site surveying was conducted on 20 random sites with a 1ha or more scale. Furthermore, six sites were selected where satellite imagery could discern the damaged areas. At these locations, the damaged area estimated by the framework was compared with the actual observed damaged area to assess accuracy. These rapid and cost-effective landslide mapping techniques can accurately estimate the location and extent of landslides and enhance the precision of sensitivity models and land management strategies.

Key Words
image classification; inventory map; landslide; object-based image analysis; satellite

Address
Hwan-Hui Lim, Enok Cheon and Seung-Rae Lee: Water Infrastructure Research Center, K-water Research Institute, Daejeon 34141, Republic of Korea
Seung-Min Lee: The 21st Infantry Division of the Republic of Korea Armed Forces, Yang-gu, Korea
Eu Song: Landslide Team, Department of Forest Environment and Conservation, National Institute of Forest Science,
Seoul 02455, Republic of Korea
Jun-Seo Jeon: Department of Geotechnical Engineering Research, Korea Institute of Civil Engineering and Building Technology,
Goyang-si 10223, Republic of Korea


Abstract
The goal of this work is to examine how a fiber-reinforced thermoelastic half-space with voids is affected by the gravity field and viscosity. The displacement, stress, and temperature distributions' analytical formulas are obtained from the normal mode analysis. The problem is analytically addressed using a three-phase-lag model. Use MATLAB programming to determine the physical fields with appropriate boundary conditions and carry out numerical computations. Examine the outcomes in the absence and presence of gravity, viscosity as well as reinforcement. Graphs are used to visualize and analyze computational findings. Theoretical as well as numerical results reveal that all the field variables are sensitive towards the gravity field, the viscosity, and the reinforcement.

Key Words
gravity; fiber-reinforced; normal mode analysis; three-phase-lag model; visco-thermoelastic

Address
Mohamed I.A. Othman, Samia M. Said, Rania A. Fathy and Esraa M. Gamal: Department of Mathematics, Faculty of Science, Zagazig University, P.O. Box 44519, Zagazig, Egypt

Abstract
Construction on waterlogged ground presents significant challenges for geotechnical engineers due to the low bearing capacity, high water table, and risks of post-construction settlement, all of which can compromise the stability of buildings. This study aims to investigate the settlement behavior of foundations on such terrains and recommend suitable foundation types to safely support building loads. To achieve these objectives, three-dimensional coupled consolidation analyses were performed to evaluate the bearing capacities of shallow footings with dimensions of 1.22 x 1.22 m2 and 1.83 x 1.83 m2. The results showed ultimate load capacities of approximately 10 kN and 21 kN, respectively, for these footings on waterlogged ground. To enhance these capacities, the use of pit sand as a filling material was explored, yielding substantial improvements. The bearing capacity of the 1.22 x 1.22 m2 footing increased by a factor of 9, while the 1.83 x 1.83 m2 footing saw a sixfold improvement. In addition, alternative foundation solutions were evaluated to achieve higher load-bearing capacities. These included raft foundations, single piles, pile groups, and piled raft foundations. Among these, a single pile demonstrated an ultimate load capacity of 300 kN, while a (2 x 2) pile group supported up to 400 kN. The piled raft foundation exhibited the highest capacity, with an ultimate load of 620 kN. These findings provide valuable insights into effective foundation designs for waterlogged conditions, enabling safer and more reliable construction practices.

Key Words
bearing capacity; coupled consolidation analysis; footings; waterlogged condition

Address
Mukhtiar Ali Soomro, Shaokai Xiong, Naeem Mangi and Sharafat Ali Darban: School of Mechanics and Civil Engineering, China University of Mining and Technology, Xuzhou, Jiangsu, P.R. China
Dildar Ali Mangnejo: Department of Civil Engineering, Mehran University of Engineering and Technology, Shaheed Zulfiqar Ali Bhutto Campus,
Khairpur Mir's Sindh, Pakistan

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