bluuebunny/crossref_metadata_2025_split huggingface dataset:
Anisotropic Failure in Foliated Rock Tunnels: Comparison between Deformational Behavior and Confined Pressure
Authors: Peng SHA , Shuyu GAO , Yiwen ZHAO , Mossa A S 
Published: November 2020

Abstract
Foliated rock mass, such as slate, schist, and phyllite, is widely distributed in Northwest China. During tunnel excavation, some geotechnical problems are encountered in the surrounding rock, such as excessive over break and intense deformation by asymmetric squeezing, because of low strength, poor self-stationary, and intense anisotropy of structural strength. The large deformation results in intense damage of the primary support and splitting of the secondary support, which can significantly influence the construction and security of tunnels. Anisotropic failure in foliated rock tunnels under high stress conditions has become an engineering challenge. The deformational anisotropy of both rock and underground structures has drawn increasing attention in the field. The relative orientation of foliation plays an essential role on the deformational behavior of layered surrounding rocks by laboratory experiments and numerical simulations. Meanwhile, the symmetrical rigid support structure cannot effectively resist the asymmetric deformation exhibited by the excavation in foliated rock mass. Consequently, the excessive confined pressure generated between surrounding rock and support is essential for anisotropic failure in tunnels. In-situ monitoring tests of deformation and contact pressure were conducted in different positions of sections within a deep-buried tunnel in the Lanzhou–Chongqing railway. The comparison results indicated that the contact pressure of the support system showed irregular space distribution, which agreed with the concentrated deformation position of the surrounding rock. However, the monitoring data showed that the occurrence of failure obviously lagged behind the stabilization of convergence deformation. The internal confined pressure could last for a long time period than the deformation monitored outside. The failure of the support takes place in the weak axis plane because of its small lateral anti-bending rigidity. The authors believe that the proposed findings will be a step further in supporting the design of tunnels passing through foliated rock mass under high in-situ stress conditions.
Predicting the settlement of Urumqi subway based on wavelet denoising and BP neural network
Authors: Zhang J Q , Qin Y J , Xie L F 
Published: November 2020

Abstract
In this study, we propose a model to accurately predict the ground subsidence caused by subway excavation using the wavelet denoising model and BP neural network. First, we develop an optimal denoising model by comparing and analyzing the denoising effect of different wavelet denoising parameters. The model is used to reduce the noise of the monitoring data. Then, we utilize BP neural network to develop a prediction model in which the proposed denoising model is used. Finally, we apply the proposed model to Urumqi subway. The results demonstrate the rationality and accuracy of the proposed model.
Analysis of TBM disc cutter wear: a case study of a water conveyance tunnel project in Xinjiang, China
Authors: Ban Chao , Gong Qiuming , Zhou Xiaoxiong , Li Shuyuan 
Published: November 2020

Abstract
Disc cutter is one of the most significant tools for TBM excavation and it is also a part that is most likely to consume. Its high cost and complicated maintenance process often bring great troubles to a project. Exploring the wear law of disc cutter can not only promote TBM excavation efficiency but also effectively save the cost. In this paper, the wear data of 671 disc cutters over a 3688-meter-long advancing distance was collected from a water conveyance tunnel project in Xinjiang, China, and the wear law of disc cutter as well as the influence of interactions among cutters on disc cutter wear were analysed. It was found that the wear velocity of one single cutter was high in the initial stage, and then it gradually decreased as the cutter constantly wore. The wear velocity of cutter increases greatly when it’s turned from outer area into front area due to its unbalanced wear while serving in outer area. The wear of a cutter increases with the increase of its installation radius, however, this phenomenon is not obvious in outer area, which is mainly because of interactions among cutters, the weaker the interaction among cutters are, the severer the wear of the cutters will be. This study can provide a useful guidance for cutter replacing process and cutterhead layout design in TBM tunnelling projects.
Study on Underpinning Scheme of Viaduct Pile Foundation Crossed by Shield Tunnel
Authors: Liangliang Zhang 
Published: November 2020

Abstract
Rapid developments in domestic metro construction could inevitably result in cross-engineering conflicts between metro lines and existing bridge pile foundations. Pile underpinning technology has been successfully applied to such projects to ensure the operating safety of viaducts and synchronous construction of metro lines. One section tunnel of Jinan Metro Line R2 is selected as the research object in this study. First, the processes of pile underpinning and tunnel crossing construction are numerically simulated using finite element software. Next, the deformation law of underpinning structures is studied and the engineering risk points are determined. Finally, the design scheme of pile underpinning is proven to be correct and reasonable. The results are as follows: (1) The underpinning structure presents a trend of overall settlement. The horizontal displacement of the pile body occurs in the form of a bow. Maximum deformation occurs at the underpinning beam and top of the pile. (2) The influence area of the soil surface is approximately 4 m outside the underpinning beam, and the deformation values of the underpinning system meet construction requirements. (3) The following construction steps are recommended. Step 1: Pre-jacking constructing. Step 2: Pile cutting. Step 3: Jack removal and underpinning beam and pile cap construction. Step 4: Road surface backfilling and repair. The shield machine should then be allowed to pass. (4) This paper provides targeted risk management measures. For example, isolation piles should be set on both sides of the tunnel.
Analytical solutions for the internal forces of lining structure in shallow double-arched tunnel subject to unsymmetrical loads
Authors: Li Xiaochang , Yang Song , Dai Rui , Ai Zubin , Zhang Chao , Huang Xin 
Published: November 2020

Abstract
This paper presents analytical solutions for the internal forces of lining structure in shallow double-arched tunnel subjected to unsymmetrical loads, mainly for the section of arch rings. The force method is employed during the derivation. The internal forces obtained from the analytical solutions are compared with that from the numerical simulation by FEM model utilizing the load-structure-method. It is found that the largest positive bending moment appears at the arch crown, while larger negative bending moment is located at both haunches of arch rings. The axial forces of both ends of arch rings are larger than that at the arch crown, which indicates that the side and middle walls are in larger compression than the arch crown. The larger shear forces of arch rings appear at the cross section approaching the top of side walls, which may be caused by the application of elastic resistance to the side wall. The comparison results and variation trend verify the applicability of presented analytical solutions for the double-arched tunnel subjected to unsymmetrical loads.
Research on the Mechanism and Treatment Technique of Invert Floor Heave After the Penetration of Large Cross-section Tunnel in Slight Inclined Stratum
Authors: Ma Kaimeng , Li Wuhong , Li Jianjun , Wang Haijun , Zheng Jieyuan , Zhang Junru 
Published: November 2020

Abstract
The newly built Chengdu–Guiyang Railway Gaopo Tunnel crosses through an interstratified rock mass of slightly inclined mud-sand. Sometime between the completion of the main structure and the construction of the monolithic ballast-less track, some sections began to bulge or even crack with a maximum deformation of up to 46 mm. At the same time, the vault jet concrete began to peel, causing significant risks in and challenges to the construction of the ballast-less track and the succeeding operations. In this study, the mechanism of and treatment techniques for invert floor heave following penetration of a large-cross-section tunnel into a slightly inclined stratum were investigated. In the study, the in-situ stress values and physical and mechanical parameters of the surrounding rock were obtained through field testing, and the extracted parameters were used in theoretical analysis based on discrete element numerical calculation to determine the applicable mechanism of invert floor heave. Finally, the implementation effects of different treatment techniques were compared and analyzed using the control variable method to identify final treatment measures. The results of this study reveal the following. (1) The heaving section of the invert floor in the tunnel area primarily comprised thin to medium-thick or interbedded mudstone and sandstone with argillaceous cement and was, in general, gently inclined. The joints of the rock mass were relatively well developed and broken. The effects of tectonic stress were not strong, and vertical stress was dominant. The swelling of the surrounding rock was weak. (2) The rock layer cracked as a result of the bending deformation of the layered surrounding rock in the unfavorable force direction. The argillaceous cement was lost or diluted in the presence of water. The weakening of the interlayer connection up to and including failure was an important contributory factor to the invert floor heave. (3) In treating the invert floor heave problems induced by joint surface weakening, the control effect of deepening the inversion was determined to be superior to those obtained by increasing the bolt length or strengthening the support stiffness. Based on these conclusions, a comprehensive management method involving the construction of a circular cavern using double linings and a 12-m long bolt was selected as a replacement treatment to effectively control the deformation. These results provide a reference for the design and construction of similar projects in the future.
Formation process of paste HDN slurry in gravel stratum
Authors: Shuyi Luo , Weiran Huang , Jinsheng Mi 
Published: November 2020

Abstract
At present, due to the complex geological conditions and long-distance drive, scheduled and unscheduled cutter head intervention maintenance during shield tunneling has become a major innovation in shield engineering in China. Therefore, paste HDN has been successfully applied to cutter head intervention under pressure, but corresponding research work on its film-forming mechanism and process is lacking. Film-forming experiments and theoretical analysis of the paste indicated that the film-forming process of the paste during gravel-stratum formation can be divided into two stages: Seepage blocking of the forming pore diameter and forming of a mud cake on the excavation surface. The seepage process was completed almost instantaneously, and the forming process of a 5–10 cm mud cake required 1–2 days. In addition, a mud diffusion model was established for investigating the mud infiltration process. The results of the aforementioned experiments were applied to the cutter head intervention of Guangzhou Metro and Lanzhou Metro, and this application ensured the efficient and safe completion of the intervention task.
Study on Design of Tunnel Lining Reinforced by Combination of PCM Shotcrete and FRP Grid Technique
Authors: Han Wei , Jiang Yujing , Gao Yuan , Koga Dairiku 
Published: November 2020

Abstract
The purpose of this paper is to investigate the reinforcing effect of the fiber-reinforced plastic (FRP)-polymer shotcrete mortar (PCM) technique on degraded tunnel lining based on the finite difference method. One adverse condition that cavities exist between the lining and rock masses was concerned, and another adverse condition was considered, namely, that due to the existence of the cavity, the rock mass located above the cavity underwent large deformation that may have exerted excessive pressure on the lining. This pressure was defined as loosening pressure; In addition, the degree of deterioration was defined to represent the degraded level of the lining concrete compared to the original strength of the concrete. The limit state design method of the Moment-Axial force (M-N) performance curve was proposed to determine whether the structure is in a safe state. The results show that when the lining deterioration degree is 0% and 50%, the location of (M, N) is all distributed inside the corresponding M-N performance curves, which indicates that the reinforcing measures can meet the safety requirement, while when the lining deterioration degree is 80%, ten sets of cases (four cases for ground class DI and six cases for ground class DII) where the M-N values of several strengthening measures distributed outside the corresponding M-N performance curves were summarized, and these cases should be avoided in the corresponding engineering. The results of this investigation can provide a valuable reference for study on the reinforcing behavior with the FRP-PCM technique.
Reasonable Width of Narrow Coal Pillars Along Gob-side Driving Entries in Gas Outburst Coal Seams: Simulation and Experiment
Authors: Hao LIU , Yu-jun ZUO , Wen-ji-bin SUN , Zhong-hu WU , Lu-jing ZHENG 
Published: November 2020

Abstract
In gob-side entry driving, the coal pillar width determines the stability of the surrounding rock and the pillar itself. Thus, to improve the stability of gas outburst coal seams, the reasonably narrow width of the coal pillars of the 40403 working face of the Shengyuan coal mine 4# was theoretically determined. Through two-dimensional simulations, the surrounding rock stability for a roadway with different coal pillar widths was evaluated. The mechanism of the surrounding rock displacement and stress distribution with the increase of the coal pillar width was also defined; for pillar widths of 2–4, 4–6, and 6–10 m, the vertical stress distribution was approximately triangular, trapezoidal, and parabolic, respectively. The coal pillar displacement was significantly greater on the goaf side than on to the roadway side. As the width of the coal pillar was incremented, its displacement on the goaf side increased, while that on the roadway side remained relatively small. The combination of the simulation results with on-site measurements finally revealed that 5 m is a reasonably narrow coal pillar width. Then, the findings were successfully applied to the 40403 working face of the Shengyuan coal mine 4#, achieving good outburst prevention and cost reduction.
A Review on Seismic Response and Aseismic Measures of Fault-crossing Tunnels
Authors: Zhang L F , Li R H , Liu H , Fang Z B , Wang H B , Y Yuan , Yu H T 
Published: November 2020

Abstract
Several earthquakes have challenged the traditional view that the seismic performance of tunnels is excellent. The seismic damage of these tunnels has led scholars and engineers to study the seismic response of tunnels and underground facilities. Many earthquake damage investigations of mountain tunnels reveal that fault or fracture zone is one of the most critical factors leading to tunnel damage. In this paper, the mechanisms of seismic damages and the main factors that influencing the seismic response of fault-crossing tunnels have been explained. Based on two different aseismic philosophies, different aseismic measures of fault-crossing tunnels including buffer layer, fiber concrete, flexible joint, grouting and enlarging tunnel across have been review, and the advantages and disadvantages of different aseismic measures as well as their application scope have been assessed. The ideal aseismic design of fault-crossing tunnels is as follows: verify the fault activity, accurately estimate the possible displacement and the earthquake intensity of the fault area, and then combine the advantages of different aseismic measures, set up composite aseismic measures at the place where the tunnel crosses the fault zone. It is believed that the present study will help in a better understanding of the seismic response of fault-crossing tunnels and have some guidance of aseismic design of fault-crossing tunnels in engineering practice.
Study on the optimum grouting materials and their performance in the TBM tunnel collapse reinforcement project
Authors: Weiwei HAN , Xiaoguo WANG , Lujia HAN 
Published: November 2020

Abstract
Considering the water inrush and collapse accident involving a tunnel boring machine (TBM) in a tunnel of the Qingdao Metro Line 1, the difficulties in grouting reinforcement in the collapse area were analyzed in order to avoid the adverse effects of grouting on the TBM equipment. The zoning governance method was chosen to solve these problems. The performance requirements of grouting materials for different areas were analyzed, after which the key properties of the materials were tested and the optimum was determined. For the water gushing area, polyurethane material was the common option, whereas for the shield area, a new high-expansion grouting material with low-strength was chosen. For the cutter head area, cement silicate grout modified by adding bentonite and quick-setting additives was tested, with the resulting material showing low strength and a quick-setting property. For the tunnel vault area, cement silicate grout and polymer-modified material were deemed suitable. After testing its viscosity change, we found that the polymer-modified material had a viscosity stabilization period. Thus, it was subsequently used at the key area. The selection of materials could reduce the consolidation risk of cutter disc and shield shell in the TBM. The research findings provide useful reference for similar projects.
Progressive Deformation Failure Characteristics of Highway Tunnel Working Face in Sand Pebble Stratum
Authors: Lu Junfu , Zhu Yi , Luo Aolei 
Published: November 2020

Abstract
The sand pebble stratum is typically unstable with discrete particles. The most important constituent elements are sand and pebbles. The surrounding rock of tunnels in the sand and pebble stratum has prominent engineering problems, such as being loose, easy to collapse, and unstable when exposed to water. Therefore, it is critical to ensure the safety of tunnel construction in this stratum. This paper studies the failure modes of surrounding rock on sand and pebble tunnel working face of different excavation footage, and the formation of subsidence law starting from the micro-mechanical and motion characteristics of particulate matter. This study is based on the Bai Heqiao tunnel of the Wudu expressway in Gansu Province. The results show that the instability failure of the surrounding rock mainly occurs in the upper part and sliding area in front of the tunnel working face. The sliding area is a curved body after the failure of the tunnel working face. The deformation and failure of the surrounding rock in the lower half of the tunnel working face are relatively small, and are gradually transferred from the vault to the surface, resulting in the subsidence of the surface and collapse. The deformation degree of the surrounding rock in the region closer to the tunnel vault is more obvious. After the formation is stabilized, the maximum subsidence deformation occurs above the tunnel vault. The final settlement amount of the stratum is also different with different footage. The smaller the excavation footage, the smaller the stratum settlement amount. Therefore, the appropriate excavation footage is selected as the principal safety control index during the excavation with the short-step method. The research results provide the necessary reference for the fine design and construction of tunnel engineering in the sand pebble stratum.
A fast automatic extraction method for rock mass discontinuity orientation using fast k-means++ and fast silhouette based on 3D point cloud
Authors: Wu Wei , Zhang Keshen , Zhu Hehua 
Published: November 2020

Abstract
In this paper, a fast automatic extraction method for rock discontinuity orientation using fast k-means++ and fast silhouette based on three-dimensional (3D) point cloud is proposed. The main contributions of the proposed method include: (1) a concept of base vector is proposed, (2) a fast k-means++ algorithm and a fast clustering validity index of silhouette are proposed and combined to automatically achieve a fast optimal grouping of discontinuities, and (3) the generation and optimization of independent discontinuity based on a double-clustering algorithm. The proposed method consists of three steps : (1) point cloud preprocessing, (2) optimal grouping of discontinuities, and (3) discontinuity generation and optimization. Several cases, including two polyhedral models under laboratory conditions and two rock slope models, are adopted to verify the accuracy and efficiency of the proposed method. A sensitivity analysis is performed to determine the optimal parameters. The results show that the proposed method can automatically achieve a fast and effective extraction of discontinuity orientations compared with the classical method, Slob (2010), Riquelme et al. (2014) and Li et al. (2016), and the efficiency is significantly improved compared with Rousseeuw (1987), Arthur and vassilvitskii (2007) and Li et al. (2016).
Research on the deformation and failure mode of rock slope with multiple locking segment failure characteristics
Authors: Hongnan QIN , Haitao MA , Zhengxing YU 
Published: November 2020

Abstract
Landslides are the most critical types of geological disasters in China, seriously threatening the safety of life and property of the inhabitants in the surrounding areas. Most landslides in China are large and giant rock landslide slope failures of large and giant rocks. Brittle failure of multiple locking sections usually accompanies rock slope failure. The locked section is significant for the early identification of rock slopes, slope deformation control, and slope failure prevention. This study uses the ground-based synthetic aperture radar technology to obtain the surface deformation data of the entire process of slope failure. By analyzing the development law of slope surface deformation before landslide failure, the dynamic process and evolution model of the time–space evolution of slope deformation and failure are proposed. The finding of the research shows that the deformation time-series curve of slope failure with multiple locking sections completely differs from the typical three-stage theory of slope failure deformation with creep characteristics. The failure process of each locking segment before the failure of the critical locking segment is accompanied by the transverse expansion of the shear failure of the sliding surface and the pulling failure of the trailing edge. After the failure of the last key-locking section, the final landslide failure will be formed. The entire process is a process of energy accumulation and downward movement, manifested by the stage displacement of the sliding mass, the mixed deformation characteristics of oscillation, and rising trend of the monitoring curve. Based on the characteristics of the entire surface deformation data in the landslide failure process, the research results prove the typical failure mode of rock slope with three sliding-tension cracking-shearing sections. The research results are critical in identifying the failure mode, analyzing slope stability, predicting landslide failure, and judging the scale of the landslide.