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CONTENTS
Volume 34, Number 4, August25 2023
 

Abstract
This study evaluates the seismic fragilities in fill slopes in South Korea through parametric finite element analyses that have been barely investigated thus far. We consider three slope geometries for a slope of height 10 m and three slope angles, and two soil types, namely frictional and frictionless, associated with two soil states, loose and dense for frictional soils and soft and stiff for frictionless soils. The input ground motions accounting for four site conditions in South Korea are obtained from one-dimensional site response analyses. By comparing the numerical modeling of slopes using PLAXIS2D against the previous studies, we compiled suites of the maximum permanent slope displacement (Dmax) against two ground motion parameters, namely, peak ground acceleration (PGA) and Arias Intensity (IA). A probabilistic seismic demand model is adopted to compute the probabilities of exceeding three limit states (minor, moderate, and extensive). We propose multiple seismic fragility curves as functions of a single ground motion parameter and numerous seismic fragility surfaces as functions of two ground motion parameters. The results show that soil type, slope angle, and input ground motion influence these probabilities, and are expected to help regional authorities and engineers assess the seismic fragility of fill slopes in the road systems in South Korea.

Key Words
fill slope; finite element analysis; ground motion characteristic; seismic fragility assessment; site conditions; slope angle

Address
Dung T.P. Tran, Youngkyu Cho, Hwanwoo Seo and Byungmin Kim: Department of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology, 50, UNIST-gil,
Eonyang-eup, Ulju-gun, Ulsan 44919, Republic of Korea

Abstract
The present paper evaluates seismic bearing capacity of rock masses subjected to loads of strip footings using the upper bound method. A general formula was proposed to evaluate the seismic bearing capacity considering both the horizontal and vertical accelerations of the earthquake and the effects of footing embedment depth simultaneously. Modified Hoek-Brown failure criterion was employed for the rock mass. Some comparisons were made with the available solutions and the finite element numerical models to show the accuracy of the developed upper bound formulations. The obtained results show significant improvement compared to the other available solutions. By increasing the horizontal earthquake acceleration from 0.1 to 0.3, the bearing capacity was reduced by up to 39%, while the effect of the vertical earthquake acceleration depends on its direction. An upward acceleration in the range of zero to 0.2 results in an increase in the bearing capacity by up to 24%, while the downward earthquake acceleration has an adverse effect. Also, by increasing the embedment depth of the footing from zero to 5 times the footing width, the value of seismic bearing capacity was raised about 86%. The obtained results were presented as design tables for use in practical applications.

Key Words
Hoek-Brown; rock mass; seismic bearing capacity; strip footings; upper bound

Address
Saeed Shamloo and Meysam Imani: Geotechnical Engineering Group, Amirkabir Univercity of Technology, Garmsar Campus, Iran

Abstract
Pipe pile walls are commonly used as retaining structures for excavation projects, particularly in densely populated coastal cities such as Hong Kong. Pipe pile walls are preferred in reclaimed land due to their cost-effectiveness and convenience for installation. However, the pre-bored piling techniques used to install pipe piles can cause significant ground disturbance, posing risks to nearby sensitive structures. This study reports a well-documented case history in a reclamation site, and it was found that pipe piling could induce ground settlement of up to 100 mm. Statutory design submissions in Hong Kong typically specify a ground settlement alarm level of 10 mm, which is significantly lower than the actual settlement observed in this study. In addition, lateral soil movement of approximately 70 mm was detected in the marine deposit. The lateral soil displacement in the marine deposit was found to be up to 3.4 and 3.1 times that of sand fill and CDG, respectively, mainly due to the relatively low stiffness of the marine deposit. Based on the monitoring data and site-investigation data, a 3D numerical analysis was established to back-analyze soil movements due to the installation of the pipe pile wall. The comparison between measured and computed results indicates that the equivalent ground loss ratio is 20%, 40%, and 20% for the fill, marine deposit and CDG, respectively. The maximum ground settlement increases with an increase in the ground loss ratio of the marine deposit, whereas the associated influence radius remains stationary at 1.2 times the pipe pile wall depth (H). The maximum ground settlement increases rapidly when the thickness of marine deposit is less than 0.32H, particularly for the ground loss ratio of larger than 40%. This study provides new insights into the pipe piling construction in reclamation sites.

Key Words
3D numerical modelling; case history; pipe pile wall; weak layer

Address
Hu Lu: School of construction engineering, Shenzhen Polytechnic University, Nanshan, Shenzhen, China
Rui-Wang Yu: Shanghai Tunnel (Hong Kong) Company Limited, North Point, Hong Kong
Chao Shi: School of Civil and Environmental Engineering, Nanyang Technological University, 639798, Singapore
Wei-Wei Pei: Wenzhou Design Assembly Company Ltd., Wenzhou, 325000, China

Abstract
Response of the pipeline crossing fault is considered as the large strain problem. Proper estimation of the pipeline response plays important role in mitigation studies. In this study, an advanced continuum modeling including material non-linearity in large strain deformations, hardening/softening soil behavior and soil-pipeline interaction is applied. Through the application of a fully nonlinear analysis based on an explicit finite difference method, the mechanics of the pipeline behavior and its interaction with soil under large strains is presented in more detail. To make the results useful in oil and gas engineering works, a continuous pipeline of two steel grades buried in two clayey soil types with four different crossing angles of 30, 45, 70 and 90 with respect to the pipeline axis have been considered. The results are presented as the fault movement corresponding to different damage limit states. It was seen that the maximum affected pipeline length is about 20 meters for the studied conditions. Also, the affected length around the fault cutting plane is asymmetric with about 35% and 65% at the fault moving and stationary block, respectively. Local buckling is the dominant damage state for greater crossing angle of 90 with the fault displacement varying from 0.4 m to 0.55 m. While the tensile strain limit is the main damage state at the crossing angles of 70 and 45, the cross-sectional flattening limit becomes the main damage state at the smaller 30 crossing angles. Compared to the stiff clayey soil, the fault movement resulting 3% tensile strain limit reach up to 40% in soft clayey soil. Also, it was seen that the effect of the pipeline internal pressure reaches up to about 40% compared to non-pressurized condition for some cases.

Key Words
buried steel pipes; continuous pipelines; fault crossings; nonlinear soil behavior; soil-pipe interaction; strick-slip fau

Address
Hadi Khanbabazadeh: Department of Engineering, Gebze Technical University, Kocaeli, Turkey
Ahmet Can Mert: Department of Civil Engineering, Istanbul Kutlur University, 34158 Istanbul, Turkey

Abstract
Granite and marble are widely produced and utilized in the construction industry, resulting in significant waste production. It is essential to manage this waste appropriately and repurpose it in recycling processes to ensure sustainability. The utilization of waste materials such as marble and granite waste (MGW) has become increasingly important in geotechnical engineering to improve the physical and mechanical properties of weak soils. This study investigated the applicability of utilizing MGW and cement (C)-MGW mixtures to improve clayey soil. A series of model plate loading tests were carried out in a specialized circular test tank to assess the influence of MGW and C-MGW mixing ratios on clayey soil samples. The samples were prepared by blending MGW and C-MGW in predetermined proportions. It is found that the bearing capacity of clay soil increased by approximately 71% when using MGW and C additives. Moreover, the consolidated settlement values of the clay soil decreased up to 6 times compared to the additive-free case.

Key Words
clayey soil; marble and granite waste; model test; soil improvement; waste disposal

Address
Baki Bagriacik and Gökhan Altay: Department of Civil Engineering, Çukurova University, Balcali Campus Sariçam, Adana, Türkiye
Cafer Kayadelen: Department of Civil Engineering, Osmaniye Korkut Ata University,
Karacağlan Campus, Merkez, Osmaniye, Türkiye

Abstract
Inclined piles are commonly used in civil engineering constructions where significant lateral resistance is required. Many researchers proved their positive performance on the seismic behavior of the supported structure and the piles themselves. However, most of these numerical studies were done within the framework of linear elastic or elastoplastic soil behavior, neglecting therefore the soil non-linearity at low and moderate soil strains which is questionable and could be misleading in dynamic analysis. The main objective of this study is to examine the influence of the pile inclination on the seismic performance of the soil-pile-structure system when both the linear elastic and the nonlinear soil models are employed. Based on the comparative responses, the adequacy of the soil's linear elastic behavior will be therefore evaluated. The analysis is conducted by generating a three-dimensional finite difference model, where a full interaction between the soil, structure, and inclined piles is considered. The numerical survey proved that the pile inclination can have a significant impact on the internal forces generated by seismic activity, specifically on the bending moment and shear forces. The main disadvantages of using inclined piles in this system are the bending forces at the head and pile-to-head connection. It is crucial to account for soil nonlinearity to accurately assess the seismic response of the soil-pile-structure system.

Key Words
inclined piles; numerical analyses; seismic; soil nonlinearity; soil structure interaction

Address
Lina Jaber and Zeinab Zein: Department of Civil Engineering, Beirut Arab University, Beirut, Lebanon
Reda Mezeh and Marwan Sadek: Univ. Lille, IMT Lille Douai, Univ. Artois, JUNIA Hauts-de-France, ULR 4515 - LGCgE,
Laboratoire de Génie Civil et géo-Environnement, F-59000, Lille, France
Marc Azab: College of Engineering and Technology, American University of the Middle East, Kuwait

Abstract
The design and development of underground nuclear waste repositories should cover the performance evaluation of the different components such as the construction materials because the long term stability will depend on their response to the surrounding conditions. In South Korea, Gyeonju bentonite has been proposed as a candidate to be used as buffer and backfilling material, especially in the form of blocks to speed up the construction process. In this study, various cylindrical samples were prepared with different dry density and water content, and their physical and mechanical properties were analyzed and correlated with X-ray CT observations. The main objective was to characterize the samples and establish correlations for non-destructive estimation of physical and mechanical properties through the utilization of X-ray CT images. The results showed that the Uniaxial Compression Strength and the P-wave velocity have an increasing relationship with the dry density. Also, a higher water content increased the values of the measure parameters, especially for the P-wave velocity. The X-ray CT analysis indicated a clear relation between the mean CT value and the dry density, Uniaxial Compression Strength, and P-wave velocity. The effect of the higher water content was also captured by the mean CT value. Also, the relationship between the mean CT value and the dry density was used to plot CT dry densities using CT images only. Moreover, the histograms also provided information about the samples heterogeneity through the histograms

Key Words
bentonite; buffer material; dry density; EBS; X-ray

Address
Melvin B. Diaz, Sang Seob Kim and Gyung Won Lee, Kwang Yeom Kim: Department of Energy and Resources Engineering, Korea Maritime and Ocean University,
727, Taejongro, Yeongdo-gu, Busan, 49112, Republic of Korea
Changsoo Lee, Jin-Seop Kim and Minseop Kim: Radioactive Waste Disposal Research Division, Korea Atomic Energy Research Institute,
111 Daedeok-dero 989 Beon-gil, Yuseong-gu, 34057, Republic of Korea

Abstract
A box scale affects the shear behavior of soils in the direct shear test. The purpose of this study is to investigate the scale effect on the shear behavior of dilative granular materials by testing specimens of different heights placed in a type C shear box. Experimental tests were performed on specimens composed of glass beads with different heights and equal initial void ratios. Results showed that the peak friction and dilation angles linearly increased with the specimen height; however, the residual friction angle remained relatively constant. Similarly, the shear stiffness increased with the specimen height, rapidly reaching its peak state. Height does not have a significant effect on the total volume changes; nevertheless, a high aspect ratio can be assumed to result in global and homogeneous failure. The results and interpretations may be used as reference for recommending shear box scale in direct shear tests.

Key Words
direct shear test; glass beads; scale effect; shear behavior; shear stiffness

Address
Young-Ho Hong and Jong-Sub Lee: School of Civil, Environmental and Architectural Engineering, Korea University,
145, Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
Yong-Hoon Byun: School of Agricultural Civil & Bio-Industrial Engineering, Kyungpook National University,
80, Daehak-ro, Buk-gu, Daegu, 41566, Republic of Korea

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