Abstract
The sandwich composite structure formed by roof rock, coal pillar, and floor rock significantly affects the stability of mining areas. Simultaneously, the instability processes of composite structure need to be diagnosed by rational monitoring technology. In this study, uniaxial compression tests are implemented on the rock-coal-rock combination structures using the acoustic emission (AE) technology. The effects of the thickness of interlayer coal and loading speed on the mechanical responses and the AE behaviors of combined body are investigated. The minimum thicknesses of interlayer coal and loading speeds both evidently affect the elastic modulus and the peak strength of combined body. The evolutionary paths with the "U" type in the AE-ER curves gained by the inter-event time function can reliably characterize the macro-cracking process of composite body. The evolution characteristics of historic index (HI) and severity (Sr) acquired by the intensity analysis (IA) method can reliably characterize the cracking process of composite body. Five regions in the chart of IA are determined by the different cracking processes of composite body. The statistical distribution characteristics of HI and Sr in the five regions can provide the early warning information related to the fracture damage of composite body. The interlayer coal thicknesses and the loading speeds both affect the failure mechanism of composite structure. The present results can provide guidance for safe and efficient production in mining areas.
Address
Guangjian Liu: State Key Laboratory of Intelligent Deep Metal Mining and Equipment, Shaoxing University,
Shaoxing 312099, Zhejiang China;
Institute of Rock Mechanics, Ningbo University, Ningbo 315211, Zhejiang China
Yong Niu, Yunjin Hu: State Key Laboratory of Intelligent Deep Metal Mining and Equipment, Shaoxing University,
Shaoxing 312099, Zhejiang China
Dalang Tian: Chongqing Survey, Design and Research Institute Co., Ltd. of CREEC, Chongqing 400023, China
Yongwei Wang: School of Civil Engineering and Architecture, Hainan University, Haikou 570228, Hainan China
Liang Fu: Sichuan Shudao Railway Investment Group Co., Ltd, Chengdu 610093, Sichun China
Abstract
This study examines ground responses at five stations in eastern Taiwan (EYUL, TTN020, ECS, EHD, and TTN023) where borehole data indicate hard geological materials. The horizontal-to-vertical spectral ratio (HVSR) method, commonly used to assess site characteristics in soft-soil areas, is applied. Ground motion data are obtained from microtremors, the 2016 Meinong earthquake (far-field), and the 2022 Kuanshan-Chihshang earthquake (near-field). Microtremor HVSR analysis reveals predominant ground frequencies of 2.35 Hz at EYUL, 2.84 Hz at EHD, and 0.63 Hz at ECS, which align with the frequencies identified using earthquake HVSR at these sites. However, both microtremor and earthquake HVSR analyses are less effective at TTN020 and TTN023: the microtremor HVSR curves lack clear peaks, and the earthquake HVSR peaks differ because of variations between near- and far-field seismic characteristics. These results indicate that microtremor and seismic motion data do not always correspond. Furthermore, HVSR analysis does not effectively capture seismic velocity pulses associated with near-field effects. Consequently, the HVSR method should be used cautiously at hard sites, and a comprehensive evaluation of spectral variations is necessary for effective seismic mitigation engineering.
Key Words
hard sites; HVSR method; microtremors; seismic response; site effects
Address
Po-Hsiang Liu: Department of Civil Engineering, National Cheng Kung University, No. 1, University Road,
Tainan, 70101, Taiwan
Department of Urban Management, Kyoto University, Kyotodaigaku-katsura, Nishikyo-ku,
Kyoto 615-8540, Japan
Abstract
This paper numerically investigates using energy-absorbing foams to mitigate reverse faulting damage
on shallow foundations. Using ABAQUS and MATLAB, the study examines how trench horizontal distance
(S=2.5, 5, 7.1), depth (D=2.5, 5, 10, 12), and width (B=0.25, 0.5, 1) affect foundation rotation for aluminum and
polyurethane foams. Results show increasing polyurethane trench width from 0.25 to 1 m reduces rotation by 26%.
Depth increases beyond a D/foundation-width ratio of 0.5 significantly reduce rotation, with diminishing returns
thereafter. Optimal trench distance is 5 m, cutting rotation by up to 64% versus the 2.5-m case. Under optimal
conditions (large depth, proper spacing), polyurethane outperforms aluminum, offering up to 42% greater rotation
reduction. However, at close spacing, aluminum performs more consistently, while polyurethane can increase
rotation by up to 145%. A highly accurate rotation prediction equation (R2 near 1) is presented. Overall, foam type
and trench geometry are critical for effective fault damage mitigation.
Address
Nima Ajeli Lahiji, Behnam Adhami: Department of Civil Engineering, Islamic Azad university, CT.C., Tehran, Iran
Gholamreza Ghodrati Amiri: Natural Disasters Prevention Research Center, School of Civil Engineering,
Iran University of Science & Technology, Tehran, Iran
Elham Rajabi: Department of Civil Engineering, Tafresh University, Tafresh 39518-79611, Iran
Abstract
The large-scale generation of high-water-content dredged soils presents significant challenges due to their
low strength and high compressibility, limiting their direct use in engineering applications. This study investigates a
sustainable stabilization approach by combining lime with sugarcane bagasse fibers (SBF) to enhance the mechanical
performance and deformation characteristics of dredged soil. A comprehensive experimental program was
conducted, including direct shear and unconfined compressive strength (UCS) tests under varying fiber contents (0-
2%) and curing periods (3 h, 7 d, and 28 d), complemented by scanning electron microscopy (SEM) to examine
microstructural evolution. The results show that lime–fiber treatment significantly improves shear strength, cohesion,
internal friction angle, and UCS compared to untreated and lime-only stabilized soils. An optimal SBF content of
1.5% was identified, at which peak strength and ductility were maximized. Compared with lime-only treated soil,
the inclusion of 1.5% sugarcane bagasse fiber (SBF) increased cohesion by approximately 65.9% and significantly
enhanced the unconfined compressive strength after 28 days of curing. The internal friction angle also increased with
fiber inclusion, indicating improved interparticle interaction and resistance to shear deformation. In addition, fiberreinforced
specimens exhibited enhanced ductility with peak axial strain increasing from approximately 3-5% to 5-
10%. Fiber inclusion increased axial strain at peak stress, indicating enhanced deformation capacity and reduced
brittleness. Strength gains were more pronounced with curing time, reflecting the progressive development of
cementitious products from lime-induced hydration and pozzolanic reactions. SEM observations reveal that strength
enhancement arises from the synergistic interaction between fiber-induced interlocking and crack-bridging
mechanisms and lime-induced bonding within the soil matrix. Excessive fiber content led to agglomeration and weak
interfaces, slightly reducing strength. The findings demonstrate that lime-SBF stabilization provides an effective and
environmentally sustainable solution for improving dredged soil for geotechnical applications.
Address
Odokonyero Charles Laber, Zhehao Qiu, Patrick Banda,
Iradukunda Patrick, Jie Yin: Department of Civil Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, China
Abstract
In composite rock-soil strata, cavern excavation often induces roof collapse. To address this issue, a
generalized nonlinear failure criterion capable of describing the mechanical behavior of both soil and rock is adopted.
Using the upper bound limit analysis method, three-dimensional stability analysis models for cavern roofs are
established, considering both rectangular and elliptical cross-sections. The total energy dissipation rate of the
collapsing block is formulated, thus identifying the potential failure zone of the cavern roof. Based on this energy
dissipation rate equation, a set of quantitative stability evaluation indicators for the cavern roof is derived, and stability
charts for the roof factor of safety F and supporting pressure p/ra under various parameters are established. The
proposed method is validated through engineering case studies, numerical simulations and quantitative comparisons
with previously published research. The results indicate that the parameters of the rock and soil mass, as well as
vertical seismic forces, significantly affect the stability of the cavern roof. Under identical stability number N, the
required supporting pressure for rectangular cavern roofs is greater than that for circular ones, suggesting a higher
susceptibility to failure in rectangular configurations.
Address
Qianlong Zhu, Yuliang Lin, Ye Ma, Rongning Deng: School of Civil Engineering, Central South University, Changsha 410075, China;
National Engineering Research Center of High Speed Railway Construction Technology,Changsha 410075, China
Chao Cao, Xiaojing Li: China Construction Fifth Engineering Bureau Co. Ltd., Changsha, 410019, China
Abstract
Conventional one-dimensional site response analyses often use simplified nonlinear effective stress
models to assess porewater pressure generation and liquefaction potential in soft soils. This study evaluates the
performance of the coupled effective stress model PDMY03 using a dataset of four case histories and high-quality
centrifuge tests where liquefaction was observed. Consistent with previous research, early liquefaction during
shaking induces significant shear strains and discrepancies between nonlinear total and effective stress analyses.
Comparisons of recorded and predicted surface spectra, piezometer measurements, and subsurface accelerations
indicate that the model generally accurately predicts liquefaction onset, with some exceptions. In particular, excess porewater pressure ratios exceeding ru 0.8 are associated with shear strain levels on the order of 3 - 6%, which lead
to significant divergence between nonlinear total stress and effective stress predictions. Under these conditions, the
results show short-period deamplification and long-period amplification, depending on the timing of pore pressure
generation. In contrast, when ru < 0.6, both approaches yield similar spectral responses and ground motion
characteristics. In particular, surface waves and lateral spreading are challenging because one-dimensional shear
wave propagation does not capture their effects. Quantitatively, PDMY03 predicted porewater pressure ratios within
+-0.15 ru of measured values in three of four cases, and spectral accelerations within +-20% for periods between 0.1
and 2.0 s. Unlike previous validations of the PDMY03 model that focused on laboratory element tests, this study
provides a multi-case systematic evaluation integrating field downhole array records and controlled centrifuge
experiments. The primary limitation in predicting liquefaction and surface response is the accurate characterization of
the dynamic soil properties. In cases of poor model performance, minor adjustments to these properties have
improved predictions; specifically, variations in shear wave velocity and stiffness within approximately +-15 – 40%
resulted in significantly improved agreement with measured response spectra, pore pressure evolution, and
acceleration profiles. Overall, PDMY03 provides reliable predictions when porewater pressure evolution and shear
stiffness are well-characterized; its applicability is limited under conditions dominated by lateral spreading and
multidimensional wave propagation, highlighting the need for complementary numerical approaches in such cases.
Address
Oscar H. Moreno-Torres: Universidad Cooperativa de Colombia, Department of Civil Engineering, Sede Santa Marta, Colombia;
2Universidad del Magdalena, Department of Civil Engineering, Santa Marta, Colombia
Andrés Salas-Montoya: Universidad Nacional de Colombia, Department of Civil Engineering, Manizales, Colombia
Cristian Quintero-Castañeda: Universidad Nacional de Colombia, Department of Civil Engineering, Manizales, Colombia
