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Volume 13, Number 1, July 2017

A coupled liquid-gas-solid three-phase model, linking two numerical codes (TOUGH2/EOS3 and FLAC3D), was firstly established and validated by simulating an in-situ air flow test in Essen. Then the coupled model was employed to investigate responses of multiphase flow and soil skeleton deformation to compressed air or freshwater injection using the same simulation conditions in an aquifer of Tianjin, China. The simulation results show that with injecting pressurized fluids, the vertical effective stress in some area decreases owing to the pore pressure increasing, an expansion of soil skeleton appears, and land uplift occurs due to support actions from lower deformed soils. After fluids injection stops, soil deformation decreases overall due to injecting fluids dissipating. With the same applied pressure, changes in multiphase flow and geo-mechanical deformation caused by compressed air injection are relatively greater than those by freshwater injection. Furthermore, the expansion of soil skeleton induced by compressed air injection transfers upward and laterally continuously with time, while during and after freshwater injection, this expansion reaches rapidly a quasi-steady state. These differences induced by two fluids injection are mainly because air could spread upward and laterally easily for its lower density and phase state transition appears for compressed air injection.

Key Words
coupled liquid-gas-solid three-phase model; compressed air injection; freshwater injection; geo-mechanical analysis; effective stress

(1) Yong-Ge Zang, Dong-Mei Sun, Ping Feng:
State Key Laboratory of Hydraulic Engineering Simulation and Safety, Tianjin University, Tianjin 300072, China;
(2) Semprich Stephan:
Institute of Soil Mechanics and Foundation Engineering, Graz University of Technology, 8010 Graz, Austria.

In recent years, the amount of sludge ash (SA) has considerably increased due to rapid urbanization and population growth. In addition, its storage in landfills induces environmental pollution and health problems. Therefore, its disposal in an environmentally friendly way has become more important. The main goal of this study is to investigate the reusability of sludge ash as an additive with polypropylene fiber (PF) to stabilize marginal sand based on the compressive strength performances from UCS tests. For this purpose, a series of UCS tests was conducted. Throughout the experimental study, the used inclusion rates were 10, 15, 20 and 30% for sludge ash and 0, 0.5 and 1% for polypropylene fiber by total dry weight of the sand+sludge ash mixture and the prepared samples were cured for 7 and 14 days prior to the testing. Freezing and thawing resistance of the mixture including 10% sludge ash and 0, 0.5 and 1% polypropylene fiber was also examined. On the basis of UCS testing results, it is said that sludge ash inclusion remarkably enhances UCS performance of sand. Moreover, the addition of polypropylene fiber to the admixtures including sand and sludge ash significantly improves their stress-strain characteristics and post-peak strength loss as well as UCS. As a result of this paper, it is suggested that sludge ash be successfully reused with polypropylene fiber for stabilizing sand in soil stabilization applications. It is also believed that the findings of this study will contribute to some environmental concerns such as the disposal problem of sludge ash, recycling, sustainability, environmental pollution, etc. as well as the cost of an engineering project.

Key Words
sludge ash; polypropylene fiber; sand; unconfined compressive strength; freezing and thawing resistance; soil stabilization

(1) Hamza Güllü:
Department of Civil Engineering, University of Gaziantep, 27310, Gaziantep, Turkey;
(2) Halil I. Fedakar:
Department of Civil Engineering, Abdullah Gül University, 38080, Kayseri, Turkey.

The inverted T-type abutments are generally used in highway bridges constructed in Korea. This type of abutment is used because it has greater stability, with more pile foundations embedded in the bedrock, while simultaneously providing support for lateral earth pressure and vertical loads of superstructures. However, the cross section of inverted T-type abutments is large compared with the piers, which makes them more expensive. In addition, a differential settlement between the abutment and embankment, as well as the expansion joints, causes driving discomfort. This study evaluated the driving comfort of several types of abutments to improve driving comfort on the abutment. To achieve this objective, a traditional T-type abutment and three types of candidate abutments, namely, mechanically stabilized earth wall (MSEW) abutment supported by a shallow foundation (called "true MSEW abutment"), MSEW abutment supported by piles (called "mixed MSEW abutment"), and pile bent and integral abutment with MSEW (called "MIP abutment"), were selected to consider their design and economic feasibility. Finite element analysis was performed using the design section of the candidate abutments. Subsequently, the settlements of each candidate abutment, approach slabs, and paved surfaces of the bridges were reviewed. Finally, the driving comfort on each candidate abutment was evaluated using a vehicle dynamic simulation. The true MSEW abutment demonstrated the most excellent driving comfort. However, this abutment can cause problems with respect to serviceability and maintenance due to excessive settlements. After our overall review, we determined that the mixed MSEW and the MIP abutments are the most appropriate abutment types to improve driving comfort by taking the highway conditions in Korea into consideration.

Key Words

(1) Moon S. Nam, Jong-Nam Do:
Structure Research Division, Research Institute of Korea Expressway Corporation, 208-96, Dongbu-daero 922beon-gil, Dongtan-myeon, Hwaseong-si, Gyeonggi-do, Republic of Korea;
(2) Min-Cheol Park:
Department of Civil Engineering, Kumoh National Institute of Technology, 61 Daehak-ro,Gumi-si, Gyeongsnagbuk-do, Korea.

The failure mechanism of a deep hard rock tunnel under high geostress and high geothermalactivity is extremely complex. Uniaxial compression tests of granite at different temperatures were conducted. The complete stress-strain curves, mechanical parameters and macroscopic failure types of the rock were analyzed in detail. The brittleness index, which represents the possibility of a severe brittleness hazard, is proposed in this paperby comparing the peak stress and the expansion stress. The results show that the temperature range from 20 to 60°C is able to aggravate the brittle failure of hard rock based on the brittleness index. The closure of internal micro cracks by thermal stress can improve the strength of hard rock and the storage capacity of elastic strain energy. The failure mode ofthe samples changes from shear failure to tensile failure as the temperature increases. In conclusion, the brittle failure mechanism of hard rock under the action of thermal coupling is revealed, and the analysis result offers significant guidance for deep buried tunnels at high temperatures and under high geostress.

Key Words
deep buried tunnel; high geothermal activity; brittle failure; expansion stress

(1) Guoqing Chen, Tianbin Li, Wei Wang, Fan Guo, Hongyu Yin:
State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, #1 Dongsanlu, Erxianqiao, Chengdu 610059, Sichuan, China;
(2) Guoqing Chen:
State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, Hubei 430071, China.

Natural clays exhibit features such as structural and anisotropy. In this work, a constitutive model that is able to replicate these two salient features of natural clays is presented. The proposed model is based on the classical S-CLAY1 model, where the anisotropy of the soil is captured through the initial inclination and rotation of the yield surface. To account for the structural of the soil, the compression curve of the reconstituted soil is taken as the reference. All parameters of the proposed constitutive model have clear physical meanings and can be conveniently determined from conventional triaxial tests. This proposed model has been used to simulate the behavior of soft soil in the undrained triaxial tests and the performance of Murro embankment in terms of settlement and horizontal displacements during embankment construction and consolidation stage. Results of numerical simulations using proposed model have been compared with the field measurement data. The comparisons show that the two features significantly influence the prediction results.

Key Words
constitutive model; structural; anisotropy; soft clay; embankment

(1) Hao Zhang, Jinjian Chen, Jianhua Wang:
Department of Civil Engineering, Shanghai Jiao Tong University, Shanghai,
200240, China;
(2) Qiushi Chen:
Glenn Department of Civil Engineering, Clemson University, Clemson, SC 29634, USA.

Rock physics modeling of sandstone reservoir from gas fields of Krishna-Godavari basin represents the link between reservoir parameters and seismic properties. The rock physics diagnostic models such as contact cement, constant cement and friable sand are chosen to characterize reservoir sands of two wells in this basin. Cementation is affected by the grain sorting and cement coating on the surface of the grain. The models show that the reservoir sands in two wells under examination have varying cementation from 2 to more than 6%. Distinct and separate velocity-porosity and elastic moduli-porosity trends are observed for reservoir zones of two wells. A methodology is adopted for generation of Rock Physics Template (RPT) based on fluid replacement modeling for Raghavapuram Shale and Gollapalli Sandstones of Early Cretaceous. The ratio of P-wave velocity to S-wave velocity (Vp/Vs) and P-impedance template, generated for this above formations is able to detect shale, brine sand and gas sand with varying water saturation and porosity from wells in the Endamuru and Suryaraopeta gas fields having same shallow marine depositional characters. This RPT predicted detection of water and gas sands are matched well with conventional neutron-density cross plot analysis.

Key Words
rock physics model; rock physics template; well log data; Krishna-Godavari Basin; neutron-density cross plot

(1) Dip Kumar Singha:
Department of Geophysics, Institute of Science, Banaras Hindu University, Varanasi 221005, India;
(2) Rima Chatterjee:
Department of Applied Geophysics, Indian Institute of Technology (Indian School of Mines), Dhanbad 826004, India.

]Static Penetration Test (CPT) and Dynamic Penetration Test (DPT) are commonly used in-situ tests in a routine geotechnical investigation. Besides their use for qualitative investigation (lithology, homogeneity and spatial variability), they are used as practical tools of geotechnical characterization (resistance to the penetration, soil rigidity) and modern foundation design as well. The paper aims at presenting the results of an extensive research work on the evaluation of the 1D primary consolidation settlement of saturated clayey soils on the basis of the CPT or DPT tests. The work is based on an analysis of the correlations between the tip resistance to penetration measured in these tests and the parameters of compressibility measured by the compressibility oedometer test, through a local geotechnical database in the northern Algeria. Such an analysis led to the proposal of two methods of calculation of the settlement, one based on the CPT test and the other one on the DPT. The comparison between the predicted settlements and those computed on the basis of the oedometer test showed a good agreement which demonstrate the possbility to use the CPT and DPT tests as reliable tools of computation of foundation settlements in clayey soils.

Key Words
settlement; shallow foundation; Cone Penetration Test (CPT); Dynamic Penetration Test (DPT); clay; oedometer test; consolidation

(1) Mouna Mir:
Department of Materials Engineering, University Yahia Fares of Médéa, Faculty of Science and Technology, Ain-Dhahab, Médéa, 26000, Algeria;
(2) Ali Bouafia, Khaled Rahmani, Nawel Aouali:
Department of Civil Engineering, University Saad Dahleb, Faculty of Engineering, P.O. Box 270, R.P Blida, 09000 Blida, Algeria.

A pick cutter is a rock-cutting tool used in partial-face excavation machines such as roadheaders, and its quality is a key element influencing the excavation performance and efficiency of such machines. In this study, pick cutters with hardfacing deposits applied to a tungsten carbide insert were made with aim of increasing their durability and wear resistance. They were field-tested by being installed in a roadheader and compared with conventional pick cutters under the same excavation conditions for 24 hours. The hardfaced pick cutters showed much smaller weight loss after excavation, and therefore better excavation performance, than the conventional pick cutters. In particular, the damage to and detachment (loss) of tungsten carbide inserts was minimal in the hardfaced pick cutters. A detailed inspection using scanning electron dispersive X-ray spectrometry and three-dimensional X-ray computed tomography scanning revealed no macro- or micro-cracks in the pick cutters. The reason for the absence of cracks may be that the heads of pick cutters are mechanically worn after the tungsten carbide inserts have been worn and damaged. However, scanning revealed the presence of voids between tungsten carbide inserts and pick cutter heads. This discovery of voids indicates the need to improve production processes in order to guarantee a higher quality of pick cutters.

Key Words
pick cutter; rock cutting; partial-face machine; wear; hardfacing

(1) Soo-Ho Chang, Chulho Lee, Tae-Ho Kang, Soon-Wook Choi:
Geotechnical Engineering Research Institute, Korea Institute of Civil Engineering and Building Technology, 283 Goyangdae-Ro, ilsanseo-Gu, Goyang-Si, Gyeonngi-Do 10223, Republic of Korea;
(2) Taewook Ha:
Department of Mining and Processing Technology, Korea Resources Corporation, 199 Hyeoksin-Ro, Wonju-Si, Gangwon-Do 26464, Republic of Korea.

The underlying ground state of a railway plays a significant role in maintaining the integrity of the overlying concrete slab and ultimately supporting the train load. While effective nondestructive tests have been used to evaluate the rail track system, they can only be performed during non-operating time due to the stress wave generated by active sources. In this study, finite element numerical simulations are conducted to investigate the feasibility of detecting unfavorable substructure conditions by using a moving train load. First, a train load module is developed by converting the train load into time-variant equivalent forces. The moving forces based on the shape functions are applied at the nodes. A parametric study that takes into account the bonding state and the train class is then performed. All the synthetic signals obtained from numerical simulations are analyzed at the frequency domain using a Fast Fourier transform (FFT) and at the time-frequency domain using a Short-Time Fourier transform (STFT). The presence of a void condition amplifies the acceleration amplitude and the vibration response. This study confirms the feasibility of using a moving train load to systematically evaluate a rail track system.

Key Words
underlying ground states of railway; train load module; fourier transform; short-time fourier transform; finite element numerical simulations

(1) Song-Hun Chong, Gye-Chun Cho, Eun-Soo Hong:
Department of Civil Engineering, Korean Advanced Institute for Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea Republic of Korea;
(2) Seong-Won Lee:
Geotechnical Engineering Research Institute, Korea Institute of Civil Engineering & Building Technology, 283, Goyang-daero, Ilsanseo-gu, Goyang-si, Gyeonggi-do, 10223, Republic of Korea.

Access shaft is of critical importance to the construction and operation of underground rock caverns. It usually has a relatively large cross-section and penetrates through fill materials, soil layers, and weathered rocks before reaching the caverns excavated in solid bedrock. In this paper, the design and construction of vertical shafts are reviewed in terms of diameter, depth, geological conditions, and support structure. Three shaft alternatives, namely alternative I: vertical shaft with spiral roads, alternative II: upper shaft with spiral roads & lower tunnels, alternative III: plain shaft, are proposed based on a simplified geological profile of the Jurong formation, Singapore. The advantages and limitations of the three types of shafts are discussed. The key issues relating to shaft design and construction, such as the shaft sinking, water control, support structure, are also discussed with a series of solutions provided, such as the sequential excavation, pre-grouting and diaphragm walls.

Key Words
shaft; rock cavern; sinking; water control; support structure

(1) Xiao-Ping Zhang:
The Key Laboratory of Safety for Geotechnical and Structural Engineering of Hubei Province, School of Civil Engineering, Wuhan University, Wuhan, China;
(2) Ming Lu:
SINTEF Rock Engineering, Trondheim, Norway;
(3) Dawei Mao:
Hydro China Zhongnan Engineering Corporation, Changsha, China;
(4) Zhiye Zhao:
China Railway Siyuan Survey and Design Group Co., LtdWuhan, China;
(5) Liu Hao:
China Railway Siyuan Survey and Design Group Co., LtdWuhan, China.

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