bluuebunny/crossref_metadata_2025_split huggingface dataset:
Node Location Study of an Urban Underground Container Logistics Network
Authors: Dong Tang , Ai-lian Zhou 
Published: November 2020

Abstract
Underground logistics systems are becoming a new way to solve the problems of urban logistics delivery and surface traffic congestion. Among them, intelligent containers, as a means of transport in the underground logistics trunk network, will allow for significantly less volumes for the logistics OD (starting point to the destination of the flow of goods), where container logistics network node site selection has been a key issue of the city’s underground logistics network planning. Based on an analysis of the characteristics of urban logistics OD, this paper builds a model that targets and optimizes parameters, such as infrastructure cost and operating cost, from the perspective of the system builder. The cplex algorithm was used to solve the model. Finally, the validity and logic of the model and algorithm are verified via case study analysis.
Deformation characteristics and internal force analysis of shield hoisting construction of working shaft in silty clay strata: Case study in Jinan
Authors: Lu Yao , Liu Hongjun , Chen Jian , Su Xiuting , Liu Tao 
Published: November 2020

Abstract
Unlike a conventional shield machine, a large-diameter shield machine needs to be hoisted separately with large hoisting equipment because of its heavy weight and large volume. Therefore, hoisting process control is important for the safety of the working shaft. By examining the shield hoisting of the Jinan Yellow River Tunnel project, this paper studied the influence of large-diameter shield hoisting on the working shaft in silty clay strata under the worst working conditions (358 t shield cutterhead load + 650 t and 300 t crawler crane loads). A three-dimensional numerical model was conducted to investigate the ground settlement, horizontal and vertical displacements of the retaining wall, and internal force in the process of shield hoisting. Field monitoring data were adopted to validate the results of the numerical analysis. The results showed that the following. (1) During the shield hoisting process, the ground settlement in the hoisting area was obviously larger than that outside it, whose maximum settlement reached 7.35 mm. (2) The horizontal displacement in the center of the retaining wall was the greatest, which reached 3.4 mm. When the depth of the foundation pit was 22 m, the maximum displacement was 9.2 mm. (3) The maximum bending moment was 1625.5 k⋅Nm, located at the foundation pit depth of 22 m, which was about two-thirds of the total pit depth. (4) The monitoring data showed that the maximum ground settlement during the shield hoisting was approximately 8.4 mm. The value was 12.5% different from the simulated maximum settlement of 7.35 mm. The maximum horizontal displacement value of the retaining wall was 5.2 mm.
Study on the deformation and fracture laws of surrounding rock of a TBM tunnel in a deep composite stratum
Authors: Ren Chao , Zhu Jiajie , Liu Jinshan , Du Jianming , Yuan Junchao , Zhang Shangkun , Jiang Ming , Shen Zhihao 
Published: November 2020

Abstract
To solve the key problems of tunneling and excavation, deformation and rupture of surrounding rocks in TBM tunnel model test research in deep composite stratum was conducted. This research employed a combined strategy of physical model test and numerical simulation for studying the deformation and fracture laws of the surrounding rock in a vertical section of a TBM tunnel in deep composite strata. In this study, the main research results are 1) The “soft and hard unevenness” and “combination effect” of the composite stratum affected the overall bearing capacity of the tunnel resulting in failure at a shallower buried depth or a lower stress concentration factor. 2) When the model was only excavated and unloaded, the plastic zone was basically near the periphery of the tunnel, resulting mainly in shear failure. In the lower layer of the composite stratum tunnel, the plastic zone due to its higher strength parameters was smaller than that in the upper layer. 3) Under the premise of the axial loading and surrounding constraints, the deformation and failure mode of the TBM tunnel in the deep composite strata exhibited “X”-type failure characteristics. The vertical section of the partially excavated rock mass revealed that the rock mass at the top layer of the tunnel caused a sudden and integral shear sliding of the palm face along the oblique direction upward 50°. This research provides significant and important guidelines for solving the problems of safety in TBM tunnel construction in a deep composite stratum.
Microseismic source location in tunnels: Effect of arrival-time picking
Authors: Feng Guang-Liang , Xiao Ya-Xun , Lin Man-Qing , Yu Yang , Fu Yu 
Published: November 2020

Abstract
The microseismic (MS) monitoring technique is widely used in deep tunnels for rock mass stability monitoring and disaster warning. MS source location is the basis of the MS monitoring technique. This study investigates the effect of arrival-time picking on MS source location in a tunnel. A total of 1000 MS sources, 12,000 arrival-time pickings, and particle swarm optimization are used. Accordingly, 3796 source-locating operations are conducted for each MS source. The results show that the number of arrival-time pickings and their mode of combination significantly affect the accuracy and the stability of MS source location in a tunnel. The optimal location cannot be obtained when using the arrival-time pickings with the smallest errors. The optimal location accuracy decreases with the increase in the number of arrival-time pickings; however, the average location accuracy increases therewith. The source location accuracy significantly changes when the number of arrival-time pickings is small. The location result becomes more stable with the increasing number of arrival-time pickings. Accordingly, a suggestion involving the usage of all arrival-time pickings for MS source location in a tunnel is provided. The results will contribute to rock mass stability monitoring and disaster warning in tunnels using the MS monitoring technique.
Study on parallel flow diffusion of granular slurry in porous media
Authors: Xiao FENG , Chong XIA , Bing ZHANG , Shijie ZHANG 
Published: November 2020

Abstract
The migration velocity model and seepage pressure model of suspension grout with plane-parallel flow state in porous media were proposed based on mass conservation equation, seepage flow continuity equation, linear filtration law, and pressure gradient equations. The effect of the particle filtration process of suspension with distance on the migration velocity, pressure gradient, and seepage pressure was analysed. By using the independently developed monomer combined type osmotic grouting device, the diffusion velocity field and pressure field of cement slurry in sand layer were studied. Then, the value of model test was compared with the filtration theoretical values and without filtration theoretical values. Results show that the difference between the value of migration velocity with neglecting filtration effect and that of the model test was 1.2~17 times. With the decreased of K
c/K
0, the theoretical value and the experimental value of filtration velocity decreased along the path, and the rate of both was positively correlated with the diffusion distance. At a certain diffusion distance, the model test value and the theoretical value of seepage pressure increase with time, but the rate was different. The difference between the model test value of seepage pressure and the theoretical value considering filtration was -23~84kPa, and the deviation rate was -70%~58%. The plane-parallel flow pressure model of slurry can accurately reflect the law of seepage field of cement slurry.
Field Test Research on Film Bag Grouting in Strongly Weathered Stratum Overlying Subway
Authors: Xu Zhen , Zhu ZhiJing , Fan YanXiang , Li KeXian , Chen Xin , Jiang QiChen , Liu RenTai 
Published: November 2020

Abstract
A strongly weathered stratum needs to be reinforced by grouting before tunnel excavation due to its poor self-stability. This work studied the law of surface uplift caused by grouting in a strongly weathered stratum overlying a subway. A strongly weathered stratum overlying a subway section was taken as the research object, and the field test method was used to reveal the time and space variation characteristics of the surface uplift with grouting reinforcement. Then, the influence of the grouting reinforcement technology, quantity, and material on the maximum surface uplift value in the practical grouting process was analyzed. The results show the following. Regardless of whether film bag grouting is used or not, the uplift value of the monitoring points is directly proportional to time, and the growth rate of the uplift value tends to accelerate. The spatial distribution of the surface uplift is mainly related to its distance to the grouting point. In addition, the maximum uplift value of the film bag grouting technology is 32.1% lower than that of the ordinary grouting technology; given the same grouting materials and technology, the grouting amount increases by 50%, and the surface uplift value increases by 121%. Moreover, the C-S slurry exhibits rapid setting, a small diffusion range, and a large thickness of the grouting vein; the surface uplift value of the C-S slurry is 3.08 times that of the cement slurry. The field test research conclusion is applied to practical engineering, where the final uplift value is 1.8 to 2.5 cm, and the average permeability coefficient of the inspection hole is 3.52×10−7 cm/s, which reflects a good engineering governance effect.
Dynamic Prediction of Rock Mass Classification in the Tunnel Construction Process based on Random Forest Algorithm and TBM in situ Operation Parameters
Authors: Hou S K , Liu Y R , Li C Y , Qin P X 
Published: November 2020

Abstract
Accurately predicting the rock mass classification is of great significance to ensure the safe and efficient construction of tunnel boring machines (TBMs). On the basis of the TBM in situ operation data recorded during tunnel construction, a prediction model for rock mass classification using the random forest (RF) algorithm is proposed. Through data preprocessing, 7538 TBM excavation cycles were obtained to form a data set. Each data sample included 195 operation parameters and corresponding information on mileage and rock mass classification. Furthermore, 6784 samples were randomly selected as the training set and the remaining 754 samples as the test set. According to the changing characteristics of operation parameters, each TBM excavation cycle was divided into the empty-push phase, the rising phase, and the stable phase. On the basis of the mean decrease Gini index, seven machine parameters highly correlated with rock mass classification were selected. Then, the variation characteristics (i.e., mean value and linear fitting slope) of the seven operation parameters in the first 30 s of the rising phase were used as the input features of the RF model. Additionally, the hyperparameters in the RF model were analyzed. The quantitative results show that the prediction accuracy is up to 87.27%, indicating that the proposed model is effective for the prediction of rock mass classification.
Large deformation analysis of tunnel-surrounding rock along the expressway from Wenchuan to Maerkang, China
Authors: Cheng Qiang , Yi Du , Yuan Quan , Liu Tian-Xiang , Lei Hang , Wang Feng 
Published: November 2020

Abstract
The rock surrounding the Wenchuan–Malkang Tunnel, which consists of metasandstone, slate, and phyllite (including carbonaceous phyllite), is strongly affected by geological and tectonic factors. The large deformation of the tunnel-surrounding rock is a concerning problem. Based on the analysis of the geological characteristics of the tunnel-surrounding rock, Hoek predictive equation was used to study the relationship between the relative deformation of the tunnel-surrounding rock and the rock strength, geostress, geological strength index, and strength-to-stress ratio. Using the strength-to-stress ratio, we predicted the large deformation of the tunnel-surrounding rock and compared it with the deformation phenomena revealed during tunnel construction. Our study shows that the large deformation of tunnel-surrounding rock along the expressway from Wenchuan to Maerkang occurs primarily in soft rock, such as slate and phyllites, which are strongly affected by the geology and tectonics factors. Deformation of the tunnel-surrounding rock grows rapidly in soft rock with decreasing geological strength index and strength-to-stress ratio and with increasing ground stress. Moreover, the relationship between the schistosity strike of the steeply layered rock mass and the tunnel axis has an important influence on the tunnel-surrounding rock deformation. Tunnels where the schistosity of the surrounding rock has a strike at a small angle with the tunnel axis are more prone to large deformation.
Bench Blasting Excavation Test for Multifault Foundation Pit of DG Hydropower Station
Authors: Cai Chang , Xiang Qian , Shen Guowu , Liu Chaojian 
Published: November 2020

Abstract
A DG hydropower station is studied in a high-altitude area, where the air is thin and a fault fracture zone develops on the left and right banks of the dam foundation and riverbed dam section. To ensure the quality of the foundation pit blasting excavation and reduce the blasting disturbance to the surrounding unexcavated rock mass, a bench blasting excavation test is conducted on the dam foundation and the relaxation depth detection is adopted for the foundation rock blasting excavation. The average attenuation rate of acoustic wave velocity before and after blasting of all control points of rock mass meets the relevant standards and specifications, and the overall performance of excavation and cleaning is good. Test results show that reasonable blasting parameters are favorable for the formation of foundation excavation, and this technology can be used as a reference in similar projects.
Advance Grouting Technology for a Large Surge Tunnel
Authors: Cai Chang , Liu Chaojian , Shen Guowu , Qiu Yun , Dai Xiaochuan 
Published: November 2020

Abstract
The large water inrush during excavation construction is a prominent problem in tunnels because of their fractured surrounding rock conditions and complex lithology, which seriously affects the tunnel construction progress and safety. Advanced grouting ideas of combining plugging and draining, mainly involving draining and supplementing water plugging, have been put forward according to different geological conditions. In this study, we used three different advanced grouting techniques to dispose of the water inrush from the palm face, block the large water inrush points in time, control the water inrush from the palm face, and successfully dispose of the large water inrush from the tunnel. Through a comparative analysis, we found a more effective advance grouting technology under different geological conditions, which can be applied for future use by other researchers.
Experimental Study on Deformation Law of Soil Layer Induced by Undercut between Existing Twin Tunnels based on 3D Geomechanical Model
Authors: Wang Ke-zhong , Liu Xian-liang , Jin Zhi-hao , Dong-lingyue  , Yang-kexing  
Published: November 2020

Abstract
The underground excavation of subway station spaces between existing twin tunnels is vital for ensuring the normal flow of ground traffic during excavation, reducing costs, and protecting the environment. However, such excavation would induce the deviation of the existing tunnel segment due to the collapse upon soil layers. Based on model test theory, a large-scale geomechanical model test frame was conducted to investigate the soil layer deformation law. A high-precision multi-point extensometer and an earth pressure cell were embedded in the design position during the manufacture of the model stratum. All of the deformation and earth pressure data at each monitoring point were obtained during the whole test process, and these data were used to analyze the deformation law in three test phases: excavation and support of the station space, transverse tunnel excavation, and overload pressure exertion on the model top surface. Results showed that the deformation induced by the underground excavation space was small, and the excavation of the transverse tunnel and overload pressure on the top surface of the model were the main factors inducing the soil deformation. The maximum vertical displacement and horizontal displacement were 1.29 mm and 0.58 mm, respectively; as indicated by the geometric similarity ratio, the displacements of the corresponding points were 12.9 mm and 5.8 mm, respectively. The test also revealed that a pre-reinforced pile outside the shield tunnel could effectively limit the segment deviation and reduce the deformation of the outside soil mass. This method might be used in the excavation of underground station spaces under good geological conditions.
Characterization of Dynamic Mechanical Parameters of Rock Fracture Evolution Based on Dry Coupling Point Contact Ultrasonic Technology
Authors: Liu Yang , Qiao Lan , Li Yuan , Liu Yuan 
Published: November 2020

Abstract
The nonlinear characteristics of deep rock masses are very prominent. Accurately obtaining the dynamic mechanical parameters of rock masses and crack damage evolution can provide the necessary data basis for studying the nonlinear behavioral changes of the stress release core during the pressure relief of rock masses. An ultrasonic acquisition system based on a compact dry-coupled acoustic wave probe can adapt to the surface of the rock being monitored with various curvatures. It can monitor the ultrasonic wave at multiple locations during the entire process of uniaxial failure from the field sandstone standard sample. It can also comprehensively collect the ultrasonic wave changes in different areas of the rock during the entire process of failure. Furthermore, the evolution of cracks characterized by dynamic mechanical parameters of sandstone samples is analyzed. The results show that the dynamic Poisson ratio is relatively stable at the beginning and then gradually increases during crack development. While the dynamic elastic wave begins to accelerate down during crack develop steady gradually accelerates to decrease, and falls rapidly when the rock damage. This can serve as a precursor to damage, providing certain feasibility for the characterization of onsite rock damage.
Tunnel in situ stress measurement by hydraulic fracturing based on the iS3 platform
Authors: Ziyang Chen , Hehua Zhu , Xiaojun Li , Ruming Liu , Jinyi Du 
Published: November 2020

Abstract
In situ stress is an important fundamental design and construction parameter in tunnel engineering as the external load of tunnels, especially in case of deep tunnels in which potential geological hazards caused by high in situ stress can be often observed. This paper describes the integration of the acquisition technique and analysis method of tunnel in situ stress measurement via hydraulic fracturing into the infrastructure smart service system (iS3) platform. The hydraulic fracturing method, which is recognized as the most reliable and effective means to measure in situ stress deep in the crust, is applied in iS3 to acquire the stress information of the rock. The transient pressure analysis (PTA) method is integrated as the analysis module of iS3 because of its advantage of accurately capturing the hydraulic fracture closure event and determining the shut-in pressure (equal to the minimum horizontal principal stress) through flow regime analysis of the fracturing fluid. The hydraulic fracturing measurement based on iS3 has been applied to a deep rock highway tunnel in south-western China (maximum depth: 1259 m). The iS3 integrated system provides a valuable reference for tunnel in situ stress measurement.
Analysis of mechanical behavior of a pipe-roof based on model of anisotropic plate on elastic foundation
Authors: Song WU , Cheng-jie ZHI , Hua TANG , Yong-hao DAI 
Published: November 2020

Abstract
According to the equivalent stiffness method of elastic theory, pipe roofs can be regarded as stiffening ribs and reinforced rock and soil can be regarded as an isotropic plate. Hence, pipe roofs and reinforced rock and soil in the local area of tunnel’s arch crown can be considered as an anisotropic plate on an elastic foundation with specific constraints on the four edges. To improve the traditional elastic foundation beam model for pipe roofs, an anisotropic plate model of a pipe roof on an elastic foundation is established. The hyperbolic model is adopted for the foundation reaction. The mechanical model of a pipe roof is extended from one to two dimensions and solved by finite element method via the COMSOL partial differential equation (PDE) module. The model is used to analyze the mechanical behavior of a pipe-roof for a shallow-buried and soft rock highway tunnel. Meanwhile, the calculated results of the hyperbolic and traditional models (Pasternak model and Winkler model) are compared and analyzed. The results show that the following: (1) The stress and deformation of pipe roofs mainly appear in the section no more than 6 m ahead of the working face. The pipe roof plays a role of a supporting beam to improve the stabilization of the working face. It can effectively transfer the upper load to the un-excavated section and better distribute the stress of surrounding rock. (2) The 2D pipe-roof model overcomes defects of traditional models that cannot simulate the plane stress of the reinforced area and provides a reference for the design and construction of pipe-roofs. The longitudinal bending moment (My
) is about 14 times the size of the lateral bending moment (Mx
), which indicates that the pipe-roof has an obvious effect on My
along the tunnel. Mx
however cannot be neglected. (3) The maximum deflection difference between the hyperbolic model and Pasternak model is about 5%, and the calculated results are in good agreement with each other. The hyperbolic model considers the monotonous and bounded characteristics of sub-grade reaction varying with the displacement. The basis of the model is verified and extent of its accuracy is demonstrated.
Prediction of mechanical parameters of the surrounding rock based on Hoek-Brown criterion
Authors: Mao Jin-zhu , Huang Zhen-wei , Xiao Li-ping , Du Sheng-hua 
Published: November 2020

Abstract
The research object is F1-6, a branch of Nujiang fault zone, which is crossed by the diversion tunnel of a hydropower station in Southwest of China, the relationship between geological strength index (GSI), disturbance parameter (D) and acoustic wave velocity of rock mass is explored. The Hoek-Brown criterion based on wave velocity is applied to predict the mechanical parameters of the surrounding rock in F1-6.The feasibility of the method is verified by the in-situ test of the fracture zone (F1-6), and the deformation of tunnel after excavated is predicted by the numerical simulation method. The study show that the mechanical parameters of fault fracture zone predicted by Hoek-Brown criterionbased on wave velocity are close to the results of in-situ test. It is feasible to predict the mechanical parameters of deep fracture zone by this method, which can solve the difficulty that the mechanical parameters of deep fracture zone can not be obtained by test directly. In addition, the numerical simulation based on the derived mechanical parameters can provide guidance for the design and construction of tunnel engineering.