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CONTENTS
Volume 16, Number 4, November20 2018
 

Abstract
A reinforced concrete pedestrian tunnel is constructed under a four-track surface railway. Heavy rainfall and soil exposure to drying lead to soil with different water content throughout the year. A railway is an open utility that is subject to rainfall without control on the quantity of the water on it and when there is a tunnel under a railway, the water content of the soil around the tunnel is very influential. This research shows the effects of change of water content in the soil around a pedestrian tunnel under a four-track surface railway. The pedestrian tunnel and the soil block around the tunnel are modeled in 3D by the FEM and are studied under the vibrations induced by the moving trains on the four-track surface railway for different soil water contents and the effects of the soil water content on the dynamic behavior of the tunnel and the surrounding soil are demonstrated.

Key Words
pedestrian tunnel; four-track surface railway; moving trains induced vibrations; soil water content; dynamic analysis; FEM

Address
Ahmed Abdelraheem Farghaly: Department of Civil and Architectural Constructions, Faculty of Industrial Education, Sohag University, Sohag 82524, Egypt

Denise-Penelope N. Kontoni: Department of Civil Engineering, Technological Educational Institute of Western Greece, 1 M. Alexandrou Str., Koukouli, GR-26334 Patras, Greece

Abstract
In this paper, nonlinear vibration of Euler-Bernoulli beams resting on linear elastic foundation is studied. It has been tried to prepare a semi-analytical solution for whole domain of vibration. Only one iteration lead us to high accurate solution. The effects of linear elastic foundation on the response of the beam vibration are considered and studied. The effects of important parameters on the ratio of nonlinear to linear frequency of the system are studied. The results are compared with numerical solution using Runge-Kutta 4th technique. It has been shown that the Max-Min approach can be easily extended in nonlinear partial differential equations.

Key Words
elastic foundation; max-min approach; analytical method; Runge-Kutta 4th

Address
Mahmoud Bayat: Young Researchers and Elite club, Roudehen Branch, Islamic Azad University, Roudehen, Iran

Mahdi Bayat: Department of Civil Engineering, Roudehen Branch, Islamic Azad University, Roudehen, Iran

Mehdi Kia: Department of Civil and Environmental Engineering, University of Science and Technology of Mazandaran, Behshahr, Iran

Hamid Ahmadi: Department of Civil Engineering, Faculty of Engineering, University of Maragheh, Maragheh, Iran

Iman Pakar: Young Researchers and Elite Club, Mashhad Branch, Islamic Azad University, Mashhad, Iran

Abstract
The evaluation of Thermo-Hydro-Mechanical (THM) coupling behavior is important for the development of underground space for various purposes. For a high-level radioactive waste repository excavated in a deep underground rock mass, the accurate prediction of the complex THM behavior is essential for the long-term safety and stability assessment. In order to develop reliable THM analysis techniques effectively, an international cooperation project, Development of Coupled models and their Validation against Experiments (DECOVALEX), was carried out. In DECOVALEX-2015 Task B2, the in situ THM experiment that was conducted at Horonobe Underground Research Laboratory(URL) by Japan Atomic Energy Agency (JAEA), was modeled by the research teams from the participating countries. In this study, a THM coupling technique that combined TOUGH2 and FLAC3D was developed and applied to the THM analysis for the in situ experiment, in which rock, buffer, backfill, sand, and heater were installed. With the assistance of an artificial neural network, the boundary conditions for the experiment could be adequately implemented in the modeling. The thermal, hydraulic, and mechanical results from the modeling were compared with the measurements from the in situ THM experiment. The predicted buffer temperature from the THM modelling was about 10oC higher than measurement near by the overpack. At the other locations far from the overpack, modelling predicted slightly lower temperature than measurement. Even though the magnitude of pressure from the modeling was different from the measurements, the general trends of the variation with time were found to be similar.

Key Words
THM; neural network; waste disposal; underground research laboratory; in situ experiment

Address
Sangki Kwon: Department of Energy Resources Engineering, Inha University, Yong-Hyun dong, Namgu, Incheon, Republic of Korea

Changsoo Lee: Department of HLW disposal, Korea Atomic Energy Research Institute, Yuseong-gu, Daejeon, Republic of Korea

Abstract
Unconfined compressive strength (UCS) of high plasticity clayey soil mixed with 5 and 10 % of Portland cement and four chemical agents such as sodium hexametaphosphate, aluminum sulfate, sodium carbonate, and sodium silicate with 0, 5, 10, and 20% concentrations was comparatively evaluated. The individual and combined effects of the cement and chemical agents on the UCS of the soil mixture were investigated. The strength of the soil-cement mixture generally increases with increasing the cement content. However, if the chemical agent is added to the mixture, the strength of the cement-chemical agent-soil mixture tends to vary depending on the type and the amount of the chemical agent. At low concentrations of 5% of aluminum sulfate and 5% and 10% of sodium carbonate, the average UCS of the cement-chemical agent-soil mixture slightly increased compared to pure clay due to increasing the flocculation of the clay in the mixture. However, at high concentrations (20%) of all chemical agents, the UCS significantly decreased compared to the pure clay and clay-cement mixtures. In the case of high cement content, the rate of UCS reduction is the highest among all cement-chemical agent-soil mixtures, which is more than three times higher in comparison to the soil-chemical agent mixtures without cement. Therefore, in the mixture with high cement (> 10%), the reduction of the USC is very sensitive when the chemical agent is added.

Key Words
clay; cement; chemical-based agent; unconfined compressive strength; soil-cement-chemical interaction

Address
Yuksel Yilmaz and Aysegul Goren: Deptartment of Civil Engineering, Gazi University, 06570 Maltepe, Ankara, Turkey

Jongwan Eun: Deptartment of Civil Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska, U.S.A.

Abstract
This study evaluates the interfacial properties of composite specimens consisting of shotcrete and sprayed waterproofing membrane. Two different membrane prototypes were first produced and tested for their waterproofing ability. Then composite specimens were prepared and their interfacial properties assessed in direct shear and uniaxial compression tests. The direct shear test showed the peak shear strength and shear stiffness of the composites\' interface decreased as the membrane layer became thicker. The shear stiffness, a key input parameter for numerical analysis, was estimated to be 0.32-1.74 GPa/m. Shear stress transfer at the interface between the shotcrete and membrane clearly emerged when measuring peak shear strengths (1-3 MPa) under given normal stress conditions of 0.3-1.5 MPa. The failure mechanism was predominantly shear failure at the interface in most composite specimens, and shear failure in the membranes. The uniaxial compression test yielded normal stiffness values for the composite specimens of 5-24 GPa/m. The composite specimens appeared to fail by the compressive force forming transverse tension cracks, mainly around the shotcrete surface perpendicular to the membrane layer. Even though the composite specimens had strength and stiffness values sufficient for shear stress transfer at the interfaces of the two shotcrete layers and the membrane, the sprayed waterproofing membrane should be as thin as possible whilst ensuring waterproofing so as to obtain higher strength and stiffness at the interface.

Key Words
interface; spray; waterproofing; membrane; shotcrete; composite

Address
Byungkwan Park: School of Smarty City and Construction Engineering, University of Science and Technology (UST),
Goyangdae-Ro 283, Ilsanseo-Gu, Goyang-Si, Gyeonngi-Do 10223, Republic of Korea

Chulho Lee: 1.) School of Smarty City and Construction Engineering, University of Science and Technology (UST),
Goyangdae-Ro 283, Ilsanseo-Gu, Goyang-Si, Gyeonngi-Do 10223, Republic of Korea
2.) Department of Infrastructure Safety Research, Korea Institute of Civil Engineering and Building Technology,
Goyangdae-Ro 283, Ilsanseo-Gu, Goyang-Si, Gyeonngi-Do 10223, Republic of Korea

Soon-Wook Choiand Tae-Ho Kang: Department of Infrastructure Safety Research, Korea Institute of Civil Engineering and Building Technology,
Goyangdae-Ro 283, Ilsanseo-Gu, Goyang-Si, Gyeonngi-Do 10223, Republic of Korea

Jintae Kim and Myung-Sik Choi: Silkroad T&D Co., Ltd., Woni-Ro 341, TaeanGun, Chungcheongnam-Do 32134, Republic of Korea

Seokwon Jeon: Department of Energy Resources Engineering, Seoul National University,Gwanak-Ro 1, Gwanak-Gu, Seoul 08826, Republic of Korea

Soo-Ho Chang:1.) School of Smarty City and Construction Engineering, University of Science and Technology (UST),
Goyangdae-Ro 283, Ilsanseo-Gu, Goyang-Si, Gyeonngi-Do 10223, Republic of Korea
2.) Construction Startup Promotion Center, Korea Institute of Civil Engineering and Building Technology,
Goyangdae-Ro 283, Ilsanseo-Gu, Goyang-Si, Gyeonngi-Do 10223, Republic of Korea

Abstract
This paper addresses the issue of field measurement of excavation damage zone (EDZ) and its numerical simulation method considering both excavation unloading and blasting load effects. Firstly, a 2000 m-deep rock cavern in China is focused. A detailed analysis is conducted on the field measurement data regarding the mechanical response of rock masses subjected to excavation and blasting operation. The extent of EDZ is revealed 3.6 m-4.0 m, accounting for 28.6% of the cavern span, so it is significantly larger than rock caverns at conventional overburden depth. The rock mass mechanical response subjected to excavation and blasting is time-independent. Afterwards, based on findings of the field measurement data, a numerical evaluation method for EDZ determination considering both excavation unloading and blasting load effects is presented. The basic idea and general procedures are illustrated. It features a calibration operation of damage constant, which is defined in an elasto-plastic damage constitutive model, and a regression process of blasting load using field blasting vibration monitoring data. The numerical simulation results are basically consistent with the field measurement results. Further, some issues regarding the blasting loads, applicability of proposed numerical method, and some other factors are discussed. In conclusion, the field measurement data collected from the 2000 m-deep rock cavern and the corresponding findings will broaden the understanding of tunnel behavior subjected to excavation and blasting at great depth. Meanwhile, the presented numerical simulation method for EDZ determination considering both excavation unloading and blasting load effects can be used to evaluate rock caverns with similar characteristics.

Key Words
rock cavern; field measurement; excavation damaged zone (EDZ); numerical simulation; blasting load

Address
Yuting Zhang, Xiuli Ding, Shuling Huang, Yang Qin, Peng Li and Yujie Li: Key Laboratory of Geotechnical Mechanics and Engineering of the Ministry of Water Resources,
Changjiang River Scientific Research Institute, Wuhan, 430010, China

Abstract
A location determining method is proposed for critical sliding surface in the stability analysis of the filling materials in karst caves. First, a preliminary location of the sliding surface is determined based on simulation results which includes displacement contour and plastic zone. The sliding surface will locate on the bottom contact interface when the friction angle is relative small. However, a weakened contact interface always becomes the critical sliding surface no matter what the friction angle is. Then when the friction angle becomes larger, the critical sliding surface inside fillings can be determined by a parabola, the coefficient of which increases linearly with the friction angle under the same cohesion. Finally, the critical sliding surface approximately remains unchanged with friction angle. The influence of cohesion is similar to that of friction angle. Although affected by shape, size or position of the karst cave, the critical sliding surface mainly depends on both friction angle and cohesion. Thus, this method is always useful in determining the critical sliding surface.

Key Words
critical sliding surface; stability analysis; filling materials; karst cave

Address
P. Lin, S.C. Li, X. Huang, D.D. Pang, X.T. Wang and J. Wang:School of Qilu Transportation, Shandong University, Jinan, Shandong 250061, China

Z.H. Xu: 1.) School of Qilu Transportation, Shandong University, Jinan, Shandong 250061, China
2.) Geotechnical & Structural Engineering Research Center, Shandong University, Jinan, Shandong 250061, China
3.) SinoProbe Center-China Deep Exploration Center, Chinese Academy of Geological Sciences, Beijing 100037, China

Abstract
A three-dimensional model is constructed to simulate water infiltration in an unsaturated slope from a leaking pipe. Adaptive mesh refinement and time stepping are used, assisted by an automatic procedure for progressive steepening of the hydraulic property function for better convergence. The model is justified by comparing the simulated results with experimental data. Steady-state flow is investigated considering various pipe water pressures, locations and sizes of the opening, and soil layering. The opening size significantly affects the soaked zone around the pipe. Preferential flow dominates along the pipe longitudinal direction in the presence of a loose backfill around the pipe.

Key Words
seepage; buried pipes; water infiltration; unsaturated soil; preferential flow; centrifuge test

Address
Hong Zhu, Limin Zhang and Kit Chan:Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay,
Kowloon, Hong Kong

Chen Chen: 1.) Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay,
Kowloon, Hong Kong
2.) State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, China
3.) College of Hydraulic and Hydroelectric Engineering, Sichuan University, China

Abstract
In order to make reliable earthquake-resistant design of civil engineering structures, one of the most important considerations in a region with high seismicity is to pay attention to the local soil condition of regions. It is aimed in the current study at specifying dynamic soil characteristics of Kirikkale city center conducting the 1-D equivalent linear and non-linear site response analyses. Due to high vulnerability and seismicity of the city center of Kirikkale surrounded by active many faults, such as the North Anatolian Fault (NAF), the city of Kirikkale is classified as highly earthquake-prone city. The first effort to determine critical site response parameter is to perform the seismic hazard analyses of the region through the earthquake record catalogues. The moment magnitude of the city center is obtained as Mw=7.0 according to the recorded probability of exceedance of 10% in the last 50 years. Using the data from site tests, the 1-D equivalent linear (EL) and nonlinear site response analyses (NL) are performed with respect to the shear modulus reduction and damping ratio models proposed in literature. The important engineering parameters of the amplification ratio, predominant site period, peak ground acceleration (PGA) and spectral acceleration values are predicted. Except for the periods between the period of T=0.2-1.0 s, the results from the NL are obtained to be similar to the EL results. Lower spectral acceleration values are estimated in the locations of the city where the higher amplification ratio is attained or vice-versa. Construction of high-rise buildings with modal periods higher than T=1.0 s are obtained to be suitable for the city of Kirikkale. The buildings at the city center are recommended to be assessed with street survey rapid structural evaluation methods so as to mitigate seismic damages. The obtained contour maps in this study are estimated to be effective for visually characterizing the city in terms of the considered parameters.

Key Words
local soil condition, site response analysis, soil amplification, peak ground acceleration, spectral acceleration, seismic hazard

Address
Yetis Bulent Sonmezer: Department of Civil Engineering, Faculty of Engineering, Kirikkale University, 71450 Kirikkale, Turkey

Selcuk Bas: Department of Civil Engineering, Faculty of Engineering, Bartin University, 74100 Bartin, Turkey

Nihat Sinan Isik: Department of Civil Engineering, Faculty of Technology, Gazi University, 06500 Ankara, Turkey

Sami Oguzhan Akbas: Department of Civil Engineering, Faculty of Engineering, Gazi University, 06500 Ankara, Turkey

Abstract
The load sharing ratio (apr) of piles is one of the most common problems in the preliminary design of piled raft foundations. A series of 3D numerical analysis are conducted so that special attentions are given to load sharing characteristics under varying conditions, such as pile configuration, pile diameter, pile length, raft thickness, and settlement level. Based on the 3D FE analysis, influencing factors on load sharing behavior of piled raft are investigated. As a result, it is shown that the load sharing ratio of piled raft decreases with increasing settlement level. The load sharing ratio is not only highly dependent on the system geometries of the foundation but also on the settlement level. Based on the results of parametric studies, the load sharing ratio is proposed as a function of the various influencing factors. In addition, the parametric analyses suggest that the load sharing ratios to minimize the differential settlement of piled raft are ranging from 15 to 48% for friction pile and from 15 to 54% for end-bearing pile. The recommendations can provide a basis for an optimum design that would be applicable to piled rafts taking into account the load sharing characteristics.

Key Words
piled raft foundation; 3D numerical analysis; load sharing ratio; sand; optimum design

Address
Junyoung Ko: Department of Civil, Environmental, and Construction Engineering, Texas Tech University, 911 Boston Ave., Lubbock, TX 79409, U.S.A.

Jaeyeon Cho: Foundations and Geotechnics, Mott MacDonald, 8-10 Sydenham Road, Croydon CR0 2EE, U.K.

Sangseom Jeong: Department of Civil and Environmental Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of Korea


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