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Quick Search     Advanced Search MODERN TUNNELLING TECHNOLOGY   2021 Vol.58 Issue.1 Published 2021-02-25 1 Study on Temperature Loads and Structural Internal Force Characteristics of Large-diameter Shield-driven Railway Tunnels in a Fire Scenario WANG Mingnian1,2 HU Xiaoyue1,2 TANG Xiongjun3 DONG Yucang1,2 YU Li1,2 In order to obtain the change laws of the temperature load and structural internal force of a large-diame? ter shield-driven railway tunnel in uneven fire scenarios, first, using the software FDS the train fire model with ventilation in the fire area considered is established to research the distribution of temperature loads on the fired lining surface. Then using the software ANSYS the thermal mechanical coupling model with internal structure considered is established to focus on researching the deformation, temperature distribution and internal force change of the tunnel lining and internal structure. The results show that the fire occuring to the train in a single-tube double-track railway tunnel with ventilation in the fire area considered is an uneven fire scenario where the fire temperature load is at most 500 ℃ and the highest concrete temperature of the fired lining surface is up to 256 ℃ after being exposed to fire for 120 m. The vertical displacements of tunnel vault and bottom in fire conditions are smaller than those in non-fire conditions, the horizontal structural displacement increases slightly while the vertical displacement of track slab decreases, and the internal force of the partial structural sections changes significantly with maximum increase being nearly 1 times. The sections on the fired lining surface present a complex stress status with larger temperature stress in the local range influenced by the temperature. 2021 Vol. 58 (1): 1-9 [Abstract] ( 862 ) [HTML 1KB] [ PDF 5349KB] ( 1707 ) 10 Mechanical Mechanism of the Shear Rock Burst in Intact Surrounding Rocks HUO Mengzhe1 LIU Xiqi1 LIN Manqing2 According to numerous rock burst cases in engineering practice, the characteristics of shear rock bursts are summarized in this paper. On the basis of this a simplified mechanical model of shear rock burst is proposed. In consideration of the release of the energy stored in rock masses in rock burst area, the Cook Stiffness theory is used to investigate the shear rock bursts′ physical and mechanical processes. The failure of surrounding rock caused by the post-peak strain-softening of the constitutive curve of a potential shear plane, and the release of energy stored in rock masses during the failure processes are analyzed. Moreover, the unstable mechanism of shear rock burst is discussed. The results show that the shear rock burst results from the shear dislocation and slip along the potential shear plane, owing to the stress concentration after excavation. Furthermore, the shear rock burst causes the sudden and rapid energy release in the rock burst area and surrounding intact surrounding rocks, and results in the ejection of fractured rock masses toward the direction of the excavation face. In rock burst area and intact surrounding rock masses, the energy released at the shear plane serves as a pair of series springs. It is concluded that the shear rock burst is governed by the lithology, potential shear failure angle and the rock masses′ stiffness around the shear plane. Furthermore, it is a failure catastrophe that resulted from energy release and the progressive deterioration of the mechanical properties of surrounding rocks during the deformation processes. 2021 Vol. 58 (1): 10-18 [Abstract] ( 902 ) [HTML 1KB] [ PDF 2005KB] ( 1565 ) 19 Study on Main Controlling Factors of Surrounding Rock Stability and Support Optimization of Deep-buried Tunnels under the Coupling Action of Anchor Bolts and Rocks YU Yuanxiang YAO Yao WANG Jingbin WANG Fuyu KE Da Due to significant rheological characteristics of the surrounding rocks of deep-buried tunnels, the rock deformation range and the displacement of the tunnel wall usually become stable after installing the primary support for some time. Therefore, researching the deformation range of tunnel surrounding rocks and the displacement of tunnel walls after supporting with the anchors will provide important theoretical basis for optimization of support parameters and reserved excavation volumes. In the paper, a mechanical model of interaction between pre-stressed anchor bolt and surrounding rock is established to analyze the position of neutral point and the maximum axial force, where the relative displacement between the bolt rod and surrounding rock is zero. The calculation formulae of the tunnel rock deformation range and the tunnel wall displacement under the coupling action of excavation disturbance, bolt pre-stress and pore-water pressure are deduced based on the neutral point theory of the bolt. The results show that the deformation range of tunnel surrounding rocks as well as the displacement of tunnel walls gradually increase with increase of the excavation disturbance and pore-water pressure while reduce with increase of the bolt pre-stress. Finally, the deformation range of the tunnel surrounding rocks and the displacement of tunnel walls in the extremely unstable tunnel section are calculated according to the proposed theoretical formulae to optimize the original excavation and support schemes, by taking a water diversion tunnel in the Qinling Mountains as engineering background. 2021 Vol. 58 (1): 19-26 [Abstract] ( 720 ) [HTML 1KB] [ PDF 1979KB] ( 1003 ) 27 Cause Analysis and Treatment Measures of the Inverted Arch Heaving Disease of a High-speed Railway Tunnel under Heavy Rainfall LI Linyi1 YANG Junsheng1 WANG Lichuan1,2 WANG Shuying1 FANG Xinghua1 XIE Yipeng1 In recent years, the rainfall-induced inverted arch heaving diseases occur frequently in the railway tun? nel, which seriously affects the tunnel operation safety. Based on the inverted arch heaving case of a high-speed railway tunnel, this paper discusses the causes of the heaving disease by comprehensively considering the effects of the rainfall, the topographic and geological conditions, and the actual conditions of the drainage system. The numerical simulation method is used to reproduce the occurrence process of the disease, the characteristics of the tunnel structure stress field and seepage field during the disease occurrence are explored, and then the remediation measures are proposed in combination with the disease situation. The results show that: (1) the water-rich connectivity of the strata caused by complex geological conditions, the unpredictable high-intensity concentrated rainfall, and the partial failure of the drainage system are the main causes of the disease, and the excessive water pressure outside the tunnel caused by the above factors is the direct cause of the disease; (2) based on the FLAC3D software, an inversion analysis method for the water pressure-induced inverted arch heaving diseases is proposed, by which it reproduces the occurrence of inverted arch heaving diseases in the studied case and provides a new idea for the analysis of similar diseases; (3) based on the disease situation, the comprehensive treatment measures are adopted, including "installing of the pressure-release holes + grouting and anchorage at the tunnel bottom + adding of the drainage tunnels + treatment at the ground surface ", proving the effectiveness of the treatment measures after field implementation, which can be used as reference for similar tunnel disease remediation works. 2021 Vol. 58 (1): 27-36 [Abstract] ( 739 ) [HTML 1KB] [ PDF 6325KB] ( 1862 ) 37 Study on the Structural Stability of Mined Tunnels with Double-layer Initial Supporting Arch Cover in Soil-Rock Composite Strata Based on the Arch Section Constructed by CD Method HUANG Fei1 GAO Xin2 Based on the advantages and disadvantages of the cover excavation method, secondary lining arch cover method and double side-drift method, the double-layer initial support arch cover method is a fast construction technology for mined large-span tunnels, which is suitable for the upper-soft and lower-hard composite strata and integrates the design concept of "bridge arch" structure. Taking the typical upper-soft and lower-hard composite strata in Qingdao area as the engineering geological background, and based on the comprehensive investigation, statistics and summary of the distribution patterns and characteristics of the geotechnical parameters of the deep rock and soil masses, it establishes a structural stability analysis model for arch-covered tunnels with arch section constructed by the CD method, using the "rock thickness-span ratio" at the arch foot as the control variable. The structural deformation patterns and the plastic zone distribution characteristics of the rock mass at the arch foot are analyzed, summarized under different combinations of arch foot bedrock lithology + overburden rock thickness, and the corresponding engineering support plans and control measures are put forward. It is recommended that priority should be given to placing the arch foot on the slightly weathered bedrock, while the depth of the arch foot embedded in the rock being no less than 4 m, which could not only reduce the burial depth of the arch top, control structural deformation and reduce construction risks but also save the cost of sidewall support and realize fast construction without bracing, achieving significant engineering and economic benefits. 2021 Vol. 58 (1): 37-45 [Abstract] ( 735 ) [HTML 1KB] [ PDF 3319KB] ( 1018 ) 46 Research Progress in the Porous Media Grouting Simulation Test MENG Yan1,2 CHENG Qifeng1,3 CHEN Xi1,2 WU Wanxia1,2 HUANG Yichun1,2 Due to the characteristics of concealment and complexity of the grouting engineering, grouting simula? tion test has become an important way to study grouting process and grouting theory. In this paper, the calculation methods of the porous media grouting theories are summarized and discussed, and the current situation and development of the research on the regularity of the grouting parameters such as diffusivity, consolidation strength, grouting pressure, internal pressure of the injected media, permeability coefficient and permeability stability in porous media grouting simulation tests are also introduced. Besides, prospect is made for the research directions of porous media grouting simulation test. 2021 Vol. 58 (1): 46-53 [Abstract] ( 725 ) [HTML 1KB] [ PDF 2418KB] ( 1430 ) 54 Study on Optimization of TBM Driving Parameters Based on the Energy Consumption YANG Jihua1 GUO Weixin1 YAN Changbin2 MIAO Dong1 In TBM tunelling, energy consumptions during TBM driving are different subjected to geological condi? tions, so the study of TBM energy consumption is of great significance for economic and efficient construction. Firstly, according to the working principle of TBM, the energy consumption calculation formula and parameters optimization formula are established. Secondly, taking the double shield TBM construction in the water convey tunnel of Lan?zhou water source project as the background, the relationships between TBM energy consumption and penetration under different geological conditions are analyzed. Finally, according to a large number of measured data, the function relationships between penetration and thrust, cutter torque are fitted, and the TBM driving parameters are optimized according to energy consumption, equipment performance and stability of surrounding rock. The results show that, with the decrease of rock classification, TBM energy consumption decreases, the TBM energy consumption in class Ⅲ granite drops about 45% contrast to that in class Ⅱ granite; TBM energy consumption decreases with the increase of penetration, and the reduction decreases gradually; the penetration has exponential relationship with driving thrust and linear relationship with cutterhead torque. 2021 Vol. 58 (1): 54-60 [Abstract] ( 974 ) [HTML 1KB] [ PDF 3100KB] ( 914 ) 61 Study on Optimization of Design Parameters of One-sided Water Stopping Curtain Based on the Orthogonal Test CHEN Fudong1 LEI Mingfeng1 ZHENG Bangyou2 WU Zhigang2 YAO Yu2 The one-sided water stopping curtain has been applied in construction near the water body, but there is lack of systematic research and specification references in the design of relevant parameters. Based on the actual project, Modflow numerical simulation software is used to establish the pumping drawdown model under the one-sided water stopping curtain. The orthogonal test and design parameter optimization research are carried out in terms of the four factors affecting the water isolation effect of the one-sided water stopping curtain, including the pile length,pile diameter, permeability coefficient and engineering boundary distance. The results show that the pile length is the most significant factor affecting the water isolation effect of the water stopping curtain, followed by the distance between the water stopping curtain and the underground works; comprehensively considering the project cost and ecological environment, it is suggested that the length of the pile should be 0.7~0.8 times as much as the thickness of the phreatic aquifer, and the distance from the underground works should be less than 0.1 times of the distance between the large-scale water body and the underground works. Moreover, on the premise of meeting the design and construction feasibility requirements, it is more economical and reasonable to choose the single-row multi-head small-diameter deep mixing pile. 2021 Vol. 58 (1): 61-66 [Abstract] ( 832 ) [HTML 1KB] [ PDF 2043KB] ( 1655 ) 67 Study on Risk Assessment in Subway Station Construction Based on Principal Component Analysis JIANG Pin LI Yuanfu The construction environment of subway station is complicated with many risk sources. Great losses will be resulted in if an accident occurs. Therefore, it is very important to carry out the risk assessment in advance to reduce the risks and losses. In this paper, a three-level hierarchical structural risk index system is established based on a subway station project case, and the weight of each risk factor is assigned according to the risk occurrence probability level and risk loss level. As a multivariate statistical method, the principal component analysis method is used to build a mathematical model for principal component analysis by a matrix of linear transformation, then obtain a few potential observable comprehensive indexes (principal components) by matrix operation and finally construct comprehensive evaluation function by comprehensive indexes and the corresponding variance contribution rates, so as to calculate the comprehensive score of each risk category and reflect the magnitude of a risk by the score. As shown in the case evaluation results, the surrounding environment risks are greater than those of foundation pit and retaining structure construction, which basically reflects the actual conditions of the construction site,thus showing strong practicability of the proposed method. 2021 Vol. 58 (1): 67-74 [Abstract] ( 831 ) [HTML 1KB] [ PDF 1554KB] ( 1346 ) 75 Metro Construction Risk Assessment Based on PPC-D-S Evidence Theory ZHOU Shengshi ZHANG Ning ZHANG Xiaojuan As for the construction safety, it is very important to make a thorough study of the source and evolution process of metro construction risks and to clarify the uncertain influence of different risks on construction. Based on the background of the literature investigation, retrieval and analysis, combined with the actual metro construction situation, the index factors are selected from the five aspects of“human, machine, material, system and environment”,and the risk assessment index system is established. The projection pursuit method (PPC) is introduced to calculate and quantify the weights objectively, and a comprehensive assessment of metro construction safety is carried out by constructing a D-S evidence theory based risk assessment model. The proposed model is applied to Qingdao metro line 13 project, by which the impacts of risks are analyzed, the safety levels are classified, and effective improve?ment and avoidance measures are put forward, providing reference for the construction of similar metro projects. 2021 Vol. 58 (1): 75-83 [Abstract] ( 880 ) [HTML 1KB] [ PDF 1642KB] ( 1047 ) 84 Study on the Safety Risk Criterion for Personnel Escape in Highway Tunnel Fires under the Concept of Life Value and Injury Value HAN Xingbo1，2 XIA Yongxu1 WANG Wenbing3 CHAI Lunlei1 WANG Xing1 Smoke and high temperature are the two main factors which threaten the life safety of passengers, drivers and firefighters while a fire accident occurs in a highway tunnel. Based on the existing personnel escape conditions regarding the fire smoke and high temperature respectively, this paper defines a concept of the injury value and life value, proposes a new safety risk criterion for personnel escape with considering both harms resulted from the tunnel fire smoke and high temperature. Taking a bus fire in a highway tunnel as an example, the numerical simulation models are built to analyze the temperature and smoke distribution fields under various fire scenarios. The injury degree of personnel during the escape process at the downstream of the fire, as well as the injury degree of firefighters at different fire-fighting positions are determined according to the proposed new safety risk criterion. The results show that properly increasing the ventilation speed will be of benefit to the personnel escape; the CO is the dominant factor threatening the personnel life safety; the firefighters at the upstream of the fire have enough time to extinguish and rescue when the ventilation speed is higher than 2.5 m/s; in case of ventilation failure, fire extinguishing and rescue time should not exceed 360 s. 2021 Vol. 58 (1): 84-91 [Abstract] ( 850 ) [HTML 1KB] [ PDF 2459KB] ( 1413 ) 92 Research on Digital Project Management and Control Platform of Construction Works FANG Youliang1 SONG Shangming1 SHANG Haisong2 ZHOU Jibing2 In view of the problem that the number of projects under construction is increasing while the manage? ment strength is weak, it puts forward the concept of digital project management and control, that is, from the managerial perspective and by means of information technology, how could construction entities realize the digital management of "standardized management, remote supervision and visual supervision" for the projects under their management. Based on the model lightweight display technology, software system integration technology and other information technology, we put forward the digital project management and control platform, including the four modules of online management and control, comprehensive statistics, auxiliary functions and data reporting, which could realize the construction of dispatching management, video monitoring, monitoring measurement, shield monitoring and other subsystems, and finally achieve the goal of digital management to ensure safety, quality and progress. 2021 Vol. 58 (1): 92-98 [Abstract] ( 878 ) [HTML 1KB] [ PDF 3570KB] ( 1408 ) 99 Optimization Analysis on Spatial Variability of Tunnel Surrounding Rock Parameters Based on Constrained Random Field Theory WEN Ming1,2 ZHANG Dingli2 FANG Huangcheng2 YU Fucai1 LIU Yan1 Aiming at the problem of insufficient use of geological prospecting data in the traditional random field simulation of spatial variability of surrounding rock parameters, the constraint random field generation method based on sampling data is developed through the combination of the Karhunen-Loève series expansion method with the Kriging interpolation. Besides, combined with Monte Carlo simulation, non-intrusive stochastic finite difference analysis and stratigraphic structure model, the optimization analysis model of spatial variability of surrounding rock parameters based on constrained random field theory has been realized. This model is used for reliability analysis of the mechanical response of surrounding rocks during the construction of Hejie Tunnel. The results show that through the constraint of the surrounding rock mechanical parameters at specified location, the optimization model can introduce the known information into the reliability analysis as much as possible, reduce the discreteness from the actual condition and improve the calculation precision of reliability analysis. 2021 Vol. 58 (1): 99-108 [Abstract] ( 698 ) [HTML 1KB] [ PDF 4744KB] ( 1618 ) 109 Study on Time Series Prediction of the Tunnel Deformation Based on the Multivariable GP-DE Model ZHANG Fengrui1 JIANG Annan1 ZHAO Liang2 CHEN Wei2 GUO Kuo2 Accurate prediction and controlling of the tunnel deformation is the key point in ensuring the tunnel con? struction safety. Aiming at the insufficiency of current time series prediction method of tunnel surrounding rock deformation, a time series prediction method of the tunnel deformation based on multivariable Gauss Process (GP) -Differential Evolution Algorithm (DE) is proposed. According to the results of tunnel automation monitoring, the multivariable phase space is reconstructed, and the input dimensions are reduced by principal component analysis. On this basis, the GP-DE model is used to predict the tunnel deformation. Taking the Gaoligou tunnel in Jilin province as an example, the surrounding rock displacement on the vault crown is predicted, and the prediction results are compared with that of BP neural network and SVM model. The results show that the GP-DE model of multi-variable time series has higher prediction accuracy, and the predicted value is in good agreement with the measured value,proving that it is an effective method for tunnel displacement prediction. 2021 Vol. 58 (1): 109-116 [Abstract] ( 741 ) [HTML 1KB] [ PDF 2426KB] ( 1116 ) 117 Soil Parameters Inversion and Working Face Stability Analysis for a Shielddriven Utility Tunnel in Water-rich Strata WANG Junxiang1 XU Chenhui1 DONG Jianhua2 CHEN Sili1 KOU Haijun3 WANG Xin1 Taking the Shenyang utility tunnel project in water-rich strata as the research background, which is ex? cavated by a EPB shield machine, the vertical displacement and horizontal displacement of the ground surface caused by the EPB shield tunnelling are monitored, and the displacement development law is analyzed. According to the actual measured displacement data, the PSO-BP parameter inversion analysis method is established based on the particle swarm optimization algorithm. The displacement inverse analysis program is compiled using Fortran language, and the parameter inversion is performed using orthogonal design and ABAQUS numerical calculation method. Considering the effects of static earth pressure, active earth pressure and passive earth pressure on the working face stability, the limit supporting pressure on the shield-driven utility tunnel face is analyzed according to the inversed soil parameters. The results show that the PSO-BP parameter inversion analysis method is a feasible and effective method. When the supporting pressure ratio is 0.4, the working face is in the limit state; and with the decrease of the supporting pressure ratio, the ground surface settlement maintains an increase trend. When the effect of groundwater is considered, larger supporting pressure should be needed to ensure the stability of the working face;and the working face is in the limit stat when the supporting pressure ratio is 0.6. 2021 Vol. 58 (1): 117-126 [Abstract] ( 868 ) [HTML 1KB] [ PDF 4477KB] ( 1276 ) 127 Experimental Analysis on Mechanical Behaviors of the Nodular Cast IronReinforced Concrete Composite Tunnel Liner Slab under Loading WU Hongyu1,2 LU Junfu1 PEI Qifan1 In order to study the application feasibility of the nodular cast iron-reinforced concrete composite liner slab as the tunnel lining structure, a three-dimensional finite element analysis method is used to simulate the loading environment of the test, and analyze the mechanical characteristics of the composite liner slab under loading.The analysis results show that when the concrete component reaches the ultimate state of compression failure, the composite liner slab can withstand the vertical pressure of 2.22 MPa and the horizontal pressure of 1.11 MPa, the maximum deformation occurs at the arch crown with the value of 6.63 mm; when the nodular cast iron component reaches the ultimate state of compression failure, the composite liner slab can withstand the vertical pressure of 11.48 MPa and the horizontal pressure of 5.74 MPa, the maximum deformation occurs at the arch crown with the value of 33.16 mm; under the effect of the nodular cast iron liner slab ring, the composite liner slab's ability to withstand the surrounding rock pressure and anti-deformation capacity are increased by 5 times compared with that of concrete liner slab under compression failure, which fully reflects the advantages of high strength and high ductility of the nodular cast iron. 2021 Vol. 58 (1): 127-133 [Abstract] ( 868 ) [HTML 1KB] [ PDF 3762KB] ( 1292 ) 134 Study on the Bending Mechanics of Precast Prestressed Utility Tunnel Joints WANG Xueliang1 WANG Pengyu2 WANG Shuhong2 Alipujiang Jierula2 Joint bending stiffness is an important parameter for the design of precast prestressed utility tunnel, and at present, there is still no extant test data or formulae. It puts forward the mechanical assumptions according to the structural characteristics of the utility tunnel joints, in which the joint section is assumed to be a non-deformable rigid plate, while the elastic gasket and prestressed tendons are abstracted into springs. And on this basis, the mechanical model is established. A non-linear equation for joint bending stiffness is derived according to deformation compatibility and stress equilibrium equations. The accuracy of the joint mechanical model and the stiffness expression is verified by comparison with the results of the joint stress test. Finally, the sensitivity of the factors influencing the bending stiffness of the joints is analyzed by using the established model, and the results can provide guidance and reference for the design of precast prestressed utility tunnels. 2021 Vol. 58 (1): 134-140 [Abstract] ( 814 ) [HTML 1KB] [ PDF 2424KB] ( 790 ) 141 Simulation Analysis on Structural Cracking Damages of Railway Tunnels with Construction Joints in Water-rich Condition GUO Yonghui1 YANG Junsheng2 To clarify the influence of construction joints on the structural safety of operating tunnels in water-rich condition, taking a typical railway tunnel defects as the basis this paper uses the FLAC3D software to establish a simulation analysis model, and studies the influence laws of the internal forces, safety coefficients and deformation patterns of the lining structures with/without construction joints and under different groundwater heights. The research results show that the occurrence of the tunnel defects is not only due to the rising of the groundwater level caused by concentrated rainfall on the ground surface, but is also significantly related to existing defects (construction joints) in the lining structure; the existence of construction joints will not only change the original bearing mode of the lining, resulting in the significant increase of the axial force at the side of the construction joints and abrupt change of the bending moment, but also change the deformation mode of the lining structure, in which case the lining structure would be prone to misalignment slip along the surface of construction joints, and part of the lining structure would be bent inward, causing deformation damage. 2021 Vol. 58 (1): 141-147 [Abstract] ( 634 ) [HTML 1KB] [ PDF 3621KB] ( 1291 ) 148 Research on the Application of Steel Fiber Reinforced Concrete Segment in Shield Tunnelling Based on the Post-cracking Linear Softening Model LI Deming1 DONG Zhanwu2 WEN Shuyi1 DENG Yisan1 As a new type of composite building material, steel fiber reinforced concrete can make up for the short? comings of ordinary concrete such as low tensile strength and poor toughness, and thus has good engineering mechanical properties, but its application lacks clear theoretical support. This paper studies the post-cracking plastic behaviors of steel fiber reinforced concrete through the three-point bending test of a notched beam. By adopting the post-cracking linear softening model as the material model of the shield tunnel segment, and based on the principle of internal force equivalence, the residual plastic axial tensile strength under the post-cracking linear softening model is obtained, which is expressed by the residual elastic flexural and tensile strength. Through the sectional static equilibrium equation and the introduction of residual plastic axial tensile strength, the formula for calculating the normal section bearing capacity of steel fiber reinforced concrete structure is obtained, which is applicable to large and small eccentric compression conditions, improving the calculation system of the normal section bearing capacity of steel fiber reinforced concrete segments. Through the full-scale segment test, the rationality of the material model and the normal section calculation method is verified. 2021 Vol. 58 (1): 148-153 [Abstract] ( 714 ) [HTML 1KB] [ PDF 2004KB] ( 1122 ) 154 Analysis on Calculation Methods for the Soil Chamber Pressure in Composite Strata Shield Tunnelling in Israel AN Hongbin The shield tunnelling of the Red Line Light Rail project in Tel Aviv, Israel, traverses composite strata mainly composed by silty-fine sand, silty sand and sandstone. In light of the problem that it is difficult to reasonably calculate the soil chamber pressure of the shield in composite strata, the strata passed by the running tunnel are divided into four rock-soil groups, and on the basis of determining the physical and mechanical parameters of each rock-soil group, this paper combines Protodyakonov's theory with the empirical method, J&S method and A&K method commonly used in European norms to calculate the soil pressures of the four rock-soil groups, and analyzes the calculation results. The analysis shows that using the average value of the three calculation methods it can effectively avoid the limitations of calculating the soil pressure through a single method, and the soil chamber pressure varies with the height of the groundwater table but is independent of the thickness of the overburden soil layer. By comparing the calculation results of this method with the actual pressure while intervention, it verifies the accuracy of this method in calculating the soil chamber pressure of shield tunnelling in Israel composite strata, providing reference and guidance for the construction parameters of similar projects. 2021 Vol. 58 (1): 154-159 [Abstract] ( 620 ) [HTML 1KB] [ PDF 1972KB] ( 983 ) 160 Analysis on Mechanical and Dilation Characteristics of Phyllite Rock under Triaxial Compression Analysis on Mechanical and Dilation Characteristics of Phyllite Rock under Rocks are characterized by dilation in deformation failure process. Taking phyllite rock as the research subject, the indoor rock triaxial compression tests are conducted to reveal the strength and dilation characteristics of jointed phyllite rocks with joint angles of 5°~45°. The results show that (1) the characteristic point stress of the rock increases with the increase of the confining pressure, while the dilation characteristics diminish; (2) the peak stress of the rock decreases as the angle between the joint plane and the maximum principal stress increases; within the range of joint angle from 5° to 45°, the closure stress, cracking stress and damage stress are maximum at θ=5° and minimum at θ=25°, after which, they increase as the angle increases; (3) the dilation characteristics are quantified and described by the dilation indicator Id, which has a confining pressure effect, i.e., the dilation indicator has a good negative exponential distribution with the confining pressure; greater variability in rock dilation rates is seen under various confining pressures at small angles; (4) the md coefficient is linearly related to the angle within the joint angle range of 5°~45°, which can describe the fractal characteristics of the dilation index with the distribution of the confining pressure, reflecting the weakening effect of the angle on the variability of rock dilation with the confining pressure. 2021 Vol. 58 (1): 160-167 [Abstract] ( 635 ) [HTML 1KB] [ PDF 3781KB] ( 1097 ) 168 Model Test Study on the Influence of the Close Crossing Angles of Overlapped Shield Tunnels on Existing Tunnels in Coastal Soft Soils WANG Chaodong1 LAI Peng′an1 CAO Yang2 YANG Sheng2 In order to study the influence of a new overlapped tunnel on the existing tunnel induced by shield con? struction with different crossing angles, the shield construction processes under the crossing angle of 0°, 30°, 60°,90° are simulated and the effects on the existing tunnel stability are analyzed by a model test, taking Fuzhou metro line 2 project as the background. The study results show that during the construction process, the soil layers along the longitudinal direction of the new tunnel are mostly affected by the construction disturbance, and the closer to the working face, the more significant the construction disturbance for the soil layer; the variation law of the additional internal force at each measuring point of the existing tunnel is consistent, and the change is most obvious at the working face of the new tunnel; when the overlapped angle changes from 0° to 90°, with increase of the angle, the soil layers in the longitudinal direction of the existing tunnel are less affected by the construction disturbance at the separated section of the two tunnels, and the longitudinal internal force is also reduced gradually. However, the influence of the construction disturbance on the soil layers at the overlapped section is consistent, and the longitudinal additional internal force is slightly reduced because of the integrity of the existing tunnel. 2021 Vol. 58 (1): 168-174 [Abstract] ( 728 ) [HTML 1KB] [ PDF 2499KB] ( 1351 ) 175 Preliminary Study on Internal Forces and Deformation Laws of the Initial Support of Railway Tunnels Passing through Various Strata in the Paleogully GUAN Xiaojun The Yangcheng tunnel mainly passes through the loess stratum, soil-sand interface strata, completely weathered red sandstone stratum, etc. in the paleogully. During the construction, large deformation and cracking of the initial support were encountered. Based on the physical and mechanical tests, field monitoring and measuring as well as the numerical simulation, it studies the deformation and stress behaviors of the initial support structure of the tunnel crossing various strata in the paleogully. The study conclusions are as follows: 1) although the cohesion of sandy loess is larger, the compressive modulus and internal friction angle of the completely weathered red sandstone are larger; 2) the tunnel displacements in the soil-sand interface strata are complex and variable, with the values being still between the displacements in the loess stratum and the completely weathered red sandstone stratum. The tensile stresses would appear at the arch foot in the completely weathered red sandstone stratum and at the interface of the soil-sand strata, which should be paid attention to during construction; 3) the deformation law in the numerical simulation is the same as that in the field test. Unlike conditions in the loess and red sandstone strata, as for the soilsand interface strata, the minimum principal stress at the upper part of the interface is larger than that at other locations, and the maximum principal stress at the interface is slightly larger than that at the arch foot. 2021 Vol. 58 (1): 175-181 [Abstract] ( 631 ) [HTML 1KB] [ PDF 5034KB] ( 1239 ) 182 Analysis on Deformation Behaviors of Diaphragm Walls of an Extra-long Special-shaped Deep Foundation Pit in Nanjing Soft Soil Area GU Zhenxue1 LOU Weizhong2 CHENG Yubo1 LI Yiwei1 SONG Dewei1 SUN Yang1 In order to study deformation behaviors of the enclosure structure of the foundation pit in Nanjing soft soil area, this paper discusses the deformation causes of the enclosure structure of the foundation pit by analyzing field measured data of an extra-long special-shaped deep foundation pit in Nanjing. The results show that the lateral displacement patterns of the diaphragm walls are all in shape of a convex drum towards the foundation pit, and there are little differences between reinforced concrete bracing and steel bracing in terms of controlling the diaphragm wall deformation. The maximum lateral displacement of diaphragm wall is less than 1% of the excavation depth and generally occurs between 4 m below the excavation point and the vicinity of the excavation point. The dimensionless maximum lateral displacement of diaphragm wall decreases with the increase of the thickness of soft soil above the wall bottom, and the dimensionless depth of maximum lateral displacement of diaphragm wall increases slightly with the increase of the thickness of soft soil above the wall bottom. Compared with other foundation pit data,the heaving resistance coefficient of the foundation pit bottom is higher, and the maximum lateral displacement of diaphragm wall is also smaller in the studied case. The insertion ratio of diaphragm wall and the horizontal bracing spacing are less relevant to the diaphragm wall deformation. 2021 Vol. 58 (1): 182-189 [Abstract] ( 775 ) [HTML 1KB] [ PDF 3600KB] ( 1174 ) 190 Study on Lighting Energy Saving Technology in the Middle Section of Highway Tunnels with Low Traffic Volume LI Ke1 MA Huaiqin2 Aiming at the problem of lighting energy waste caused by low traffic flow of secondary and tertiary high? way tunnels in West Sichuan Plateau, a real vehicle running test is conducted by using TOBIIGLASESS2 eye tracker.Through direct calculation, the stopping sight distances of the drivers in the middle section of the plateau tunnels with low traffic volume under different lighting conditions are obtained, and comparison with the minimum stopping sight distance as required in Guidelines for Design of Lighting of Highway Tunnels (2014 Editoin) is made. Under the premise of ensuring the traffic safety of drivers, it is recommended that the lighting brightness design standard for the middle section of this kind of tunnels should be 0.5 cd/m2. Using Dialux software, the numerical simulation is conducted for the lighting conditions in the middle section of secondary and tertiary highway tunnels with low traffic volume on the Western Sichuan Plateau, and the engineering economy under different lighting conditions is analyzed. It is recommended that the lamps in the Balangshan tunnel should be arranged in the middle position with an unequal interval of 30 m. 2021 Vol. 58 (1): 190-196 [Abstract] ( 644 ) [HTML 1KB] [ PDF 2283KB] ( 1327 ) 197 Study on Drivers′ Eye Movement Characteristics Affected by the Fatigue Mitigation Light Belt in Highway Tunnels QIN Pengcheng1 WANG Mingnian1 BAO Yifan1 CHEN Jinyu1,2 YAN Tao1 CHEN Zhanwen1 The provision of a fatigue mitigation light belt in highway tunnels can improve drivers′ visual environ? ment. However, if its design is too complicated, drivers will shift their attention to the light belts, which will endanger the driving safety. Hence, based on the Yanglin extra-long tunnel, the eye movement characteristics of the driver in the fatigue mitigation light belt section and the other tunnel sections are tested using the eye tracker, and the law of influence of the fatigue mitigation light belt on the eye movement characteristics is obtained by comparison. The results show that the drivers′fixation range in the light belt section is expanded and distributed linearly to the tunnel walls on both sides; the drivers′fixation time on the tunnel wall in the light belt section is longer, but it is still much shorter than the fixation time on the far distance in the central main visual area; in the tunnel section with the fa? tigue mitigation light belt, the drivers′eye movement type in the central main visual area is almost gaze, with the eye saccade occupying a certain proportion in the areas of tunnel walls on both sides; when passing through the fatigue mitigation light belt section of Yanglin extra-long tunnel, the drivers′ main concern is still the road ahead and the driver can easily obtain and perceive the information of the wall pattern. 2021 Vol. 58 (1): 197-202 [Abstract] ( 751 ) [HTML 1KB] [ PDF 1524KB] ( 1823 ) 203 Study on Deformation Characteristics and Control Measures of Shallow Large-span Loess tunnels CHEN Peishuai1,2 WANG Wei1,3 WU Zhongshi1,4 YUAN Qing1,4 JIANG Hong1,5 ZHAI Shihong1,5 In order to study the deformation characteristics and the corresponding control technology of large-span loess tunnels, guide the loess tunnel design & construction and ensure the construction safety, based on a tunnel project being under construction, this paper analyzes the surrounding rock deformations and the causes according to field monitoring data of the large deformation section, as well as proposes corresponding control measures and parameters. The study results show that great differences exist in surrounding rock deformations of a shallow loess tunnel affected by the properties of overlying surrounding rocks, the surrounding rock deformation rate is generally large at the early stage of excavation with the maximum settlement rate of 54.6 mm/d; the deformation lasts for a long time and tends to converge gradually after about 45 d; the accumulative deformation is large and significantly affected by excavation disturbance, in particular, the surrounding rock deformation during the lower bench excavation accounts for about 70% of the total deformations; the large deformation process of surrounding rocks will experi? ence four stages of "fast development, sustainable development, slow development and gradual stabilization", in the stage of sustainable development it is susceptible to external environment with a large fluctuation in surrounding rock deformation rate, at the stage of slow development the invert should be closed as soon as possible to effectively restrain the deformation development of surrounding rocks; the regression curve model can be directly used to predict the deformation of soft loess tunnels. 2021 Vol. 58 (1): 203-211 [Abstract] ( 698 ) [HTML 1KB] [ PDF 4416KB] ( 941 ) 212 Study on Vertical Freezing Technology Applied in the Emergency Remediation of Foshan Metro Line 2 Project LIU Dongjun1 LIU Weijia2 XU Chao3 GAO Ruchao4 ZHAO Jingxuan5 Based on the emergency remediation case of applying the vertical freezing technology in the right line of Huyong station - Lvdaohu station section of Foshan metro line 2, the numerical modeling and monitoring data analysis methods are used to systematically research the development law and application effects of the vertical frozen wall in the water-rich sand layer. The results show that it is completely feasible to isolate the hydraulic connection between undamaged and damaged tunnel sections with the vertical freezing technology. When the target ground are frozen with multiple rows of freeze pipes, the temperature of surrounding ground will influence the development of frozen walls, and the peripheral cooling rate of the frozen wall is obviously slower than that of inside the frozen wall.During freezing construction, to improve the peripheral development speed of the frozen wall, the refrigerating powers of the peripheral refrigerators should be increased and the refrigerator numbers of peripheral freezing holes can be added when necessary. It is recommended that temperature monitoring holes should be installed between the adjacent freezing pipes of the outmost row of frozen wall (the weakest point), to accurately determine the development quality and closure time of the frozen body. 2021 Vol. 58 (1): 212-216 [Abstract] ( 632 ) [HTML 1KB] [ PDF 2980KB] ( 1227 ) 217 Study on Causes to and Treatment of Concrete Cracking of the Secondary Lining of Qilianshan Tunnel YU Hongqin1 QI Jun2 LIU Huairong1 HOU Zhigang1 LI Dewu2 To address the disease problem of secondary lining cracking in the operation period of Qilianshan tun? nel, the crack features and strike distribution conditions are investigated at the field, the cracking mechanism and causes are analyzed, as well as the treatment measures and relevant suggestions are proposed for different kinds of lining cracks according to relevant specifications and design requirements. 2021 Vol. 58 (1): 217-222 [Abstract] ( 692 ) [HTML 1KB] [ PDF 3477KB] ( 1522 ) 223 Discussion on Imaging Operation Technology in Advanced Horizontal Boreholes of Railway Tunnels FENG Tao XIE Li Subjected to the analyzer′ s experience and geological conditions at the coring location, the exploration results of the advanced horizontal drilling are often different to the actual conditions. In view of this, the industrial endoscope technology is applied to the advanced horizontal drilling for geological prediction in Fuxing tunnel on the newly-built Dali-Ruili railway. In combination with the application practice of industrial endoscope technology in the advanced geological prediction, this paper summarizes the technical requirements for the imaging operation in the advanced horizontal boreholes and proposes the corresponding quality control measures for the imaging operation, effectively improving the accuracy and timeliness of the advanced geological prediction, enhancing the guiding effect of the geological prediction on tunnel excavation construction. 2021 Vol. 58 (1): 223-228 [Abstract] ( 611 ) [HTML 1KB] [ PDF 2842KB] ( 907 )

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