Wei Liu^{1, 2, *}, Qianxiang Wu²

CMES-Computer Modeling in Engineering & Sciences, Vol.123, No.2, pp. 661-690, 2020, DOI:10.32604/cmes.2020.07764 - 01 May 2020

Abstract A utility tunnel system consists of pipes and ancillary facilities. In this paper, a finite element model of a concrete utility tunnel with pipes inside is established. Several tunnel segments were built to simulate a real utility tunnel, while the pipe was fixed by springs on the brackets in the utility tunnel. Using the discrete soil spring element to simulate the soil-structure interaction, actual earthquake records were adopted as excitation to analyze the seismic responses of pipes in a utility tunnel. Moreover, the influences of different parameters, including soil type, earthquake records, and field apparent More >

Abierdi¹, Yuzhou Xiang², Haiyi Zhong², Xin Gu², Hanlong Liu^{2, 3}, Wengang Zhang^{2, 3, *}

CMC-Computers, Materials & Continua, Vol.63, No.2, pp. 825-844, 2020, DOI:10.32604/cmc.2020.07946 - 01 May 2020

Abstract Tunnel excavation is a complicated loading-unloading-reloading process characterized by decreased radial stresses and increased axial stresses. An approach that considers only loading, is generally used in tunnel model testing. However, this approach is incapable of characterizing the unloading effects induced by excavation on surrounding rocks and hence presents radial and tangential stress paths during the failure process that are different from the actual stress state of tunnels. This paper carried out a comparative analysis using laboratory model testing and particle flow code (PFC^2D)-based numerical simulation, and shed light upon the crack propagation process and, microscopic stress More >

Yundong Han¹, Dawei Chen¹, Shaoqing Liu¹, Gang Xu²

FDMP-Fluid Dynamics & Materials Processing, Vol.16, No.1, pp. 1-19, 2020, DOI:10.32604/fdmp.2020.06525 - 01 February 2020

Abstract A series of tests have been conducted using a Cryogenic Wind Tunnel to study the effect of Reynolds number (Re) on the aerodynamic force and surface pressure experienced by a high speed train. The test Reynolds number has been varied from 1 million to 10 million, which is the highest Reynolds number a wind tunnel has ever achieved for a train test. According to our results, the drag coefficient of the leading car decreases with higher Reynolds number for yaw angles up to 30º. The drag force coefficient drops about 0.06 when Re is raised… More >

Panpan Zhai^{1, 2}, Ping Xu^{1, 2, *}

CMC-Computers, Materials & Continua, Vol.62, No.1, pp. 179-197, 2020, DOI:10.32604/cmc.2020.06474

Abstract When a tunnel is excavated below the groundwater table, groundwater flows in through the excavated wall of the tunnel and seepage forces act on it. These forces significantly affect the ground reaction curve, which is defined as the relationship between the internal pressure and radial displacement of the tunnel wall. This study investigates analytical solutions for seepage forces acting on the lining of a circular tunnel under steady-state groundwater flow. Considering the tunnel’s construction or service period and boundary conditions, the direction of maximum principal stress changes, and the input stress of the Mohr-Coulomb criterion… More >

Simone Goa Diab¹, Kristin Godang², Lil‐Sofie Ording Müller³, Runar Almaas⁴, Charlotte de Lange³, Leif Brunvand¹, Kari Margrethe Hansen¹, Anne Grethe Myhre⁵, Gaute Døhlen¹, Erik Thaulow^1,6, Jens Bollerslev^2,6, Thomas Möller¹

Congenital Heart Disease, Vol.14, No.6, pp. 996-1004, 2019, DOI:10.1111/chd.12848

Abstract Objective: We investigated bone mineral density (BMD) at different ages after the Fontan completion, and we evaluated the relationship between BMD, vitamin D levels, and pertinent patient variables.
Methods: A cross‐sectional sample of 64 patients was examined with dual‐energy X‐ray absorptiometry (DXA) scans to determine BMD. Of these patients, 24 were also examined with BoneXpert software to determine bone mass density (BMX), expressed as the bone health index (BHI). Blood samples from all patients were analyzed. Patients were divided into three different age groups; A: 4‐9 years old (n = 22), B: 10‐15 years old (n =… More >

Wei Wu^1,2,3, Yaji Jiao^2,*, Hehua Zhu^1,2,3, Rui Jin²

The International Conference on Computational & Experimental Engineering and Sciences, Vol.21, No.2, pp. 33-33, 2019, DOI:10.32604/icces.2019.05324

Abstract When shield tunnels pass through gas-bearing strata, leakage may happen through the gasketed segmental joints, which puts threats on the safety during construction and operation process. Previous studies on sealing performance of the gasketed joints have focused on the waterproof behavior. However, differences in physical characteristics between liquid and gas, lead to different permeation properties. This paper presents a combined experimental and computational study to investigate the gas sealing behavior of the gasketed joints used for a shield tunnel project, i.e., Sutong GIL Utility Tunnel, which passes through soft soil strata rich in high-pressure biogas… More >

Zixin Zhang^1,2,*, Shuaifeng Wang^1,2, Xin Huang^1,2

The International Conference on Computational & Experimental Engineering and Sciences, Vol.21, No.2, pp. 29-29, 2019, DOI:10.32604/icces.2019.04704

Abstract Block theory is widely used in numerical simulation of rock engineering due to its concision and fast-calculation. The paper proposes block theory for TBM (tunnel boring machine) tunnels to extend the traditional block theory applicative for tunnels excavated by TBM. In the proposed method, TBM-block interaction forces are taken into consideration. Subsequently, an index is proposed to estimate the stability of the TBM tunnel based on safety factor at every given chainage of the tunnel. Finally, a real water-conveyance tunnel project is studied with block theory for TBM tunnels. The simulation results include the joint More >

Gongyu Hou¹, Zhedong Xu^1,*, Xin Liu¹, Cong Jin¹

CMES-Computer Modeling in Engineering & Sciences, Vol.118, No.2, pp. 317-337, 2019, DOI:10.31614/cmes.2019.04693

Abstract This article proposes an exponential adjustment inertia weight immune particle swarm optimization (EAIW-IPSO) to enhance the accuracy and reliability regarding the selection of shield tunneling parameter values. According to the iteration changes and the range of inertia weight in particle swarm optimization algorithm (PSO), the inertia weight is adjusted by the form of exponential function. Meanwhile, the self-regulation mechanism of the immune system is combined with the PSO. 12 benchmark functions and the realistic cases of shield tunneling parameter value selection are utilized to demonstrate the feasibility and accuracy of the proposed EAIW-IPSO algorithm. Comparison More >

Ling Wu¹, Haoxue Liu², Tong Zhu², Yueqi Hu³

Intelligent Automation & Soft Computing, Vol.24, No.3, pp. 633-642, 2018, DOI:10.31209/2018.100000030

Abstract The objective of the current study was to examine how experienced and inexperienced driver behaviour changed (including heart rate and longitudinal speeds) when approaching and exiting highway tunnels. Simultaneously, the NARX neural network was used to predict real-time speed with the heart rate regarded as the input variable. The results indicated that familiarity with the experimental route did decrease drivers’ mental stress but resulted in higher speed. The proposed NARX model could predict synchronous speed with high accuracy. These results of the present study concern how to establish the automated driver model in the simulation More >

Ling Zhang^{1, 2}, Xiaoyan Lei¹, Jian Jiang², Qingsong Feng¹

Sound & Vibration, Vol.52, No.5, pp. 22-27, 2018, DOI:10.32604/sv.2018.04058

Abstract Underground railway vibration source strength is one of the key values used for environmental impact assessment and the evaluation of mitigation measure’s performance. However, currently there is no international standard of measuring the underground railway vibration source strength for such purposes. The available local standards and industrial guidelines do not agree on measurement locations as well as the metrics for presenting the source strength. This has caused many confusions. This paper aims to study the suitable measurement location and metrics using the data from a large scale field-testing carried out at the Nanchang underground railway… More >