[an error occurred while processing this directive]

Home | About Journal |  Editorial Board |   |  Instruction |  Subscription |  Advertisement |   |  Download |  中文  Office Online   Search     Adv Search

·Online Submission ·Manuscript Tracking ·Peer Review ·Editor Work ·Office Work ·Editor-in-chief  Journal Online ·Forthcoming Articles ·Current Issue ·Next Issue ·Archive ·Advanced Search ·Read Articles ·Download Articles ·Email Alert ·  Download · More>>

Quick Search     Advanced Search MODERN TUNNELLING TECHNOLOGY   2018 Vol.55 Issue.1 Published 2018-02-25 Article 1 Discussion of Tunnelling in Squeezed Surrounding Rock LI Guoliang LI Ning Based on the experience of tunnels with high geostress conditions constructed in China, assessment cri? terion, geological characteristics of squeezed surrounding rock and suggestions for the rock mass classification are presented. A further analysis of geological factors of rock mass integrity, thickness, structure and geostress that affect initial support deformation is conducted, a classification method, which is based on relative deformation, the degree of cracking of the initial support, soft and hard rock, and an unsymmetrical load and section dimension, is discussed, and a design method for a tunnel in squeezed surrounding rock and systematic management techniques for large deformation are proposed. 2018 Vol. 55 (1): 1-6 [Abstract] ( 875 ) [HTML 1KB] [ PDF 917KB] ( 2036 ) 7 State of the Art of Techniques and Equipment for Defect Remediation in Existing Railway Tunnels GAO Juru1 GUI Fengtao2 YUAN Wei1 ZHANG Bo1 The state of the art of the techniques and development tendency of defect remediation for existing railway tunnels are studied in terms of defect detection and safety evaluation, treatment methods and technology, adopted materials and equipment. Relevant suggestions are proposed, such as increasing the rationality of tunnel design, improving controllability of quality in the course of tunnel construction and promoting normalization of defect remediation, which can be a reference for defect remediation and safe operation in existing railway tunnels. 2018 Vol. 55 (1): 7-16 [Abstract] ( 941 ) [HTML 1KB] [ PDF 1487KB] ( 3180 ) 17 Structural Design of the Stacked Loaded Arch of Large-Span Tunnels in Upper-Soft Lower-Hard Rock Stratum SONG Chaoye HE Weiguo There aren′t many project cases of shallow large-span tunnel metro stations in rock strata that are soft on top and hard on the bottom, nor is there referential experience for a reasonable structure type and construction method for these metro stations. Based on the Xinggongjie Station of the Dalian metro, a new structure type and construction method named“stacked loaded arch for metro stations”is presented by analyzing the characteristics of loose surrounding rock of a large-span tunnel in upper-soft and lower-hard stratum, and similar project cases. So a single-arch station structure with a span of more than 20 m can be constructed. The design method and mechanical characteristics of the initial support and secondary lining for a stacked loaded arch structure are analyzed. Application practice shows that the stacked loaded arch with initial support bears the full load in the construction process,the lower structure can be built safely under its protection, ground deformation can be controlled effectively and rapid mechanization construction in rock stratum is feasible. 2018 Vol. 55 (1): 17-26 [Abstract] ( 845 ) [HTML 1KB] [ PDF 4514KB] ( 2110 ) 27 Proper Spacing of the Deformation Joints of a Bored Section of the Gongbei Tunnel WANG Xiuying TAN Zhongsheng DAI Yibo HUANG Mingli ZHAO Jinpeng A deformation joint is meant to solve the problem of structural damage induced by differential settle? ment or concrete shrinkage, but it can make it difficult to achieve a watertight tunnel. Despite the use of deformation joints, there is still a lack of quantitative analysis regarding the spacing of deformation joints. Based on the actual geological conditions and structural forms of the Gongbei tunnel on the Hongkong-Zhuhai-Macao throughfare, proper spacing of deformation joints is analyzed quantitatively by simulation. The results show that: 1) if the reinforcement effect of the pipe roof under the tunnel base is not considered，it can not meet the safety requirements for the structure, even at a deformation joint space of 22 m; 2) if the reinforcement effect of the pipe roof under the tunnel base is considered, a deformation joint space of 88 m is feasible; and 3) if the reinforcement effect of the pipe roof around the tunnel is considered, the deformation joint can be canceled for the bored section from the view of the horizontal stress and vertical displacement. A deformation joint space of no more than 88 m is feasible for the bored section of the Gongbei tunnel for the sake of safety, economy and convenience considering the differential settlement that may occur at the foundation after tunnel operation. 2018 Vol. 55 (1): 27-35 [Abstract] ( 772 ) [HTML 1KB] [ PDF 3379KB] ( 2162 ) 36 Identification of Geological Structures and Precursory Information Likely to Cause Water Inflow in Karst Tunnels YUAN Yongcai GAO Chenglu WANG Jing ZHU Yuze ZHANG Meng It is believed that certain potential environment conditions may induce water bursts and mud gushing, and certain precursory information is often noticed before these kinds of geological hazards occur. Based on engineering practice, case investigation and theoretical analysis, this paper systematically studies the occurrence rule of water inflow and mud gushing in karst tunnels, determines the inherent meaning of occurrence conditions (e.g., a water-bearing structure with pressure, a migration pathway and an external disturbance), divides them into five types of water inflow: water inflow in a fault fracture zone, water inflow in a karst cavity and pond, water inflow in a waterrich fracture, water inflow in contact zone between soluble and dissoluble rock layers, water inflow in an underground river and a karst conduit. By studying the geological and geophysical precursors to water inflow and water bursts, a comprehensive precursory information identification system is established for water inflow and water bursts and is successfully applied in the Shangjiawan Tunnel, avoiding casualties and reducing economic loss. 2018 Vol. 55 (1): 36-44 [Abstract] ( 1015 ) [HTML 1KB] [ PDF 1888KB] ( 2470 ) 45 Analysis and Control of Collapse Events during Tunnel Construction HOU Yanjuan ZHANG Dingli LI Ao Collapse is one of the most common disasters in tunnel construction, and its prevention is the focus of safety measures in tunnel construction. In light of the characteristics of surrounding rock deformation, failure, and instability, tunnel collapse events are attributed to surrounding rock instability, structure failure and/or environmental disturbance based on the statistics of typical cases, and the evolution process and formation mechanism of various collapse events are systematically studied. These three types of accidents are significantly correlated to the characteristics of surrounding rock movement and the interaction mode between the supporting and surrounding rock, and these accidents occur at the tunnel face and front, behind the tunnel face before secondary lining installation and at shallow tunnel portals. Comprehensive treatments are suggested with respect to geological surveys, detailed design,enhanced monitoring and construction management so as to avoid tunnel collapses and improve the safety of tunnel construction. 2018 Vol. 55 (1): 45-52 [Abstract] ( 888 ) [HTML 1KB] [ PDF 2367KB] ( 2200 ) 53 Analysis of the Weight Values of Common Earthquake Damages in Railway Tunnels RONG Miren1 WANG Hailong1, 2 SU Mubiao3 RONG Huren2 CAO Haiyun4 HUO Xaoyan5 Earthquakes occur frequently in China and often railway tunnels are much affected and seriously damaged as a result. The quantitative and rapid assessment of earthquake damage and loss is very important. The fuzzy analytic hierarchy process, weight value calculation of the 10/10-18/2 score scale method and the validation method for calculation consistency ratio CR are introduced. Hierarchical structure models of the rail, main structure and annex of the railway tunnel structure, which is often damaged by earthquakes, are established. The weight values of railway tunnel structures and common earthquake damages are calculated by the 10/10-18/2 score scale method, and the calculation consistency ratio CR is verified. The results show that it is more reasonable and accurate to calculate weight values with the 10/10-18/2 score scale method based on a hierarchical model of the tunnel structure and common earthquake damages for the quantitative assessment of railway tunnel damage and loss. The research results can be used as a basis for grading earthquake damage and economic loss assessment for railway tunnels, and it is feasible for the quantitative evaluation of damage to a single railway tunnel. 2018 Vol. 55 (1): 53-64 [Abstract] ( 808 ) [HTML 1KB] [ PDF 1676KB] ( 2005 ) 59 Sub-Classification System for Rocky Surrounding Rock of the Qingdao Metro WU Shengzhi WANG Mingnian LIU Dagang Based on the Qingdao metro project, a sub-classification system for rocky surrounding rock is studied, and elastic longitudinal wave velocities, core recovery percentages and forms of rock cores corresponding to various grades of rock masses are obtained. In light of the research results, a sub-classification system, which includes qualitative discrimination, elastic longitudinal wave velocity and rock core condition, is established. Applicability analysis of the sub-classification shows it has a good coincidence rate and the deviation of the rock mass grade is less than one sub-classification; the new classification system is favorable for reducing the span of design parameters for rock masses of different grades, which guarantees design safety and avoids waste. Uncertainty regarding rock mass classification decreases and the grading system for rocky surrounding rock is enriched. 2018 Vol. 55 (1): 59-64 [Abstract] ( 881 ) [HTML 1KB] [ PDF 1335KB] ( 1781 ) 65 Rock Mass Quality Classification of Wudang Group Schist Based on a Corrected Q-Value WANG Zhangqiong1,2 YAN E′chuan2 WANG Yajun Rock masses with special geological backgrounds are often encountered during construction of under? ground works, and it is necessary to establish a corresponding rock mass quality classification method. In light of the features and weak points of Q-value classification, the characteristics of water sensitivity, anisotropism, unsymmetrical structure pressure and the horizontal tectonic stress of a structure are analyzed using the Wudang group schist in northwest Hubei province as an example. A corrected Q- value classification is presented considering rock mass strength, rock integrity, groundwater, geostress and occurrence of schistosity plane, and a calculation formula for Qvalue classification, which takes ground water (exposure condition and water pressure), geostress (magnitude and included angle with excavation axis) and schistosity obliquity as correction factors, is obtained. An analytical validation is conducted based on the Tongsheng tunnel on the Shiyan-Fangxian expressway, and results are consistent with the actual rock quality classification. 2018 Vol. 55 (1): 65-70 [Abstract] ( 877 ) [HTML 1KB] [ PDF 816KB] ( 2272 ) 71 Rock Burst Characteristics of Deep-Buried Tunnels Based on Complex Variable Function Theory BAI Mingzhou1,2 SHI Hai1 YI Diqing3 ZHANG Yunlong1 NIE Yicong1,2 It is important to accurately predict rock bursts in unexcavated tunnel sections for the safe and rapid construction of tunnels. Aiming at the characteristics of tunnel rock bursts, a unified solution to the stress of the circular section under the effects of lateral pressure is obtained by a complex variable function solution proposed by Muskhelishvili and based on conformal mapping function represented by the Laurent series of infinite single connected domain. With proper criteria for rock bursts, a comprehensive assessed grade of rock bursts is determined, and a comparison of the calculation results, numerical simulation results and actual results of rock bursts is conducted.The results show that: 1) stress concentrations with different degrees occur at different parts of the surrounding rock,and the maximum compressive stress mainly occurs at the crown after excavation; 2) stress concentration and abrupt change could occur at the structural surface after excavation of a deep-buried tunnel section due to the effects of tectonic stress; and 3) the analytic calculation results and numerical simulation results agree well with the actual results of rock bursts, which demonstrates the effectiveness of this analysis method with complex variable function. 2018 Vol. 55 (1): 71-77 [Abstract] ( 802 ) [HTML 1KB] [ PDF 2246KB] ( 1987 ) 78 Seismic Response of Subway Tunnels in Complicated Geological Conditions to an Oblique Incident Wave GAO Xinjun Based on the viscous-spring artificial boundary theory, a numerical model of a subway tunnel and soil foundation is established by seismic dynamic analogue simulation that considers the soil/structure dynamic interaction and wave effects. The dynamic response law of subway tunnels in strata that is interbedded with soft and hard soil layers under oblique incidence SV waves is analyzed systematically. The results show that: 1) seismic wave incident angle has a significant effect on the tunnel′s dynamic response and the dynamic response of the running tunnel decreases with an increase of the incident angle; 2) the dynamic response at the stratum interbedded with soft and hard soil layers is more obvious than that in other places under the same incident angle, which indicates this condition is unfavorable for seismic resistance; 3) the dynamic response of each point of the running tunnel tends to be consistent with decrease of the differences of the elastic modulus of soft and hard soil bodies; and 4) increasing the lining thickness reduces the displacement and bending moment of the tunnel structure at the connection of the soft soil body and the hard soil body, which increases the tunnel′s seismic behavior. 2018 Vol. 55 (1): 78-84 [Abstract] ( 871 ) [HTML 1KB] [ PDF 2979KB] ( 1114 ) 85 Back Analysis of the Internal Force on the Supporting Structure of a Multi-Centered Circular Arch Tunnel CHEN Yixin1 CUI Genqun2 SONG Lin3 It is important to understand the characteristics of the internal force distribution of the supporting struc? ture of a tunnel with multi-centered circular arch in complicated construction conditions to ensure safe tunnel construction. Based on the initial parameter method and site-measured pressures of the surrounding rock, an inversion expression for the internal force calculation of the supporting structure of the multi-centered circular arch tunnel is theoretically derived using the theory of a curved beam on an elastic foundation. Based on the measured pressures of the surrounding rock of a certain section of the Qixiaying tunnel, a back analysis is conducted for the internal force distribution of the tunnel lining structure and a safety evaluation of the weak parts of the tunnel structure is undertaken. The results show that site monitoring should be strengthened for the weak parts during construction since the bending moment and shearing force of the lining structure at the BG arc section are relatively large; monitoring and observation should also be improved since concrete cracking could occur at the tunnel crown due to bending. 2018 Vol. 55 (1): 85-91 [Abstract] ( 793 ) [HTML 1KB] [ PDF 1591KB] ( 1890 ) 92 Effects of Tangential Friction Resistance on the Stress and Deformation of a Tunnel across a Landslide Area SUN Chunping1 FAN Honghai2 LI Fang1 WANG Yuanyuan3 LI Kaitian3 Simplifying the tunnel across the landside deformation zone as an elastic foundation beam, large bend? ing deformation may occur when a tunnel section in a landslide area is long. Being a special full-buried elastic foundation beam, it′s necessary to study the effect of tangential friction resistance. A calculation model of elastic foundation beam considering the effects of tangential friction resistance is established, a gradual revision concept is introduced, a formula for calculation of the internal force and displacement is set up with the transfer matrix method, and a corresponding calculation procedure is programmed. The calculation results show the scope of the effects of the tangential friction resistance on the tunnel mainly concentrates in the area near the boundary of the landslide, and the tunnel′s internal force and displacement both decrease to some extent due to tangential friction resistance; the effect of the tangential friction resistance coefficient on the tunnel′s internal force and displacement in the landslide area is relatively small, while the effect is relatively large outside of the landslide area. 2018 Vol. 55 (1): 92-99 [Abstract] ( 792 ) [HTML 1KB] [ PDF 1497KB] ( 1765 ) 100 Analysis of Internal Force of a Tunnel Lining in the Case of the Landslide Sliding Direction Being Orthogonal to Its Axis WANG Bingqiang1 GU Shuancheng2 HE Hengwei2 Based on the Tangjiayuan highway tunnel on the Xi′an-Baoji expressway, the influential factors regarding magnitude and direction of a landslide's thrust acting on the lining of an arched tunnel with a straight wall are analyzed in light of the positional relationship between the tunnel and the sliding surface. A theoretical calculation method for the internal force distribution of a semicircle arched tunnel lining is obtained, with the sliding direction being orthogonal to the axis. Using the Tangjiayuan tunnel as an example, the internal force distribution of a tunnel lining is obtained by theoretical calculation, and the rationality and validity are verified by FEM, with the results showing that this method can be used to calculate the internal force of a tunnel lining in the case of the landslide sliding direction being orthogonal to the tunnel axis. 2018 Vol. 55 (1): 100-106 [Abstract] ( 804 ) [HTML 1KB] [ PDF 1569KB] ( 1624 ) 107 Application of Genetic Algorithm Based BP Neural Network to Parameter Inversion of Surrounding Rock and Deformation Prediction ZHOU Guannan1 SUN Yuyong2 JIA Peng3 Reliable mechanical parameters of surrounding rock are imperative for the accurate prediction of tunnel deformation. A GA-BP based neural network back analysis system is proposed and automatic searching for BP network parameters can be realized, with the efficiency of inversion analysis increasing greatly. This GA-BP intelligent back analysis system is applied to the inversion of rock mass parameters and deformation prediction for the Dadingshan tunnel passing underneath the Shenyang-Dandong expressway. The results show that the convergence speed of the GA-BP back analysis system is fast and the parameter inversion of the surrounding rock and deformation prediction is accurate. 2018 Vol. 55 (1): 107-113 [Abstract] ( 885 ) [HTML 1KB] [ PDF 3711KB] ( 1812 ) 114 Spatial Distribution Characteristics of the Full Displacement of Surrounding Rock of a Shallow-Buried Tunnel Section in Soft Rock LI Youyun1 WANG Fengcang2 ZHANG Yuwei1 HU Kunkun1 Information collection for surrounding rock displacement is important for guiding tunnel construction with NATM. Loss of displacement information due to restriction of various factors is inevitable. Based on site-measured data of full displacement in the Alatan tunnel, the release rate of surrounding rock stress at various construction stages is determined, and a 3D numerical analysis of the variation law of the full displacement at the ground surface of a shallow portal section and surrounding rock at the tunnel crown is performed. The results indicate that: 1)the maximum vertical displacement at the surface, measuring 33 mm during tunnel construction, conforms to the measured data, while the vertical displacement at the surface measuring point is far larger than that of the horizontal displacement, and the vertical displacement loss is 42.86% of the total displacement of the surrounding rock; 2) the calculated vertical displacement of the surrounding rock at the tunnel crown is 60 mm, which basically conforms to the site-measured data; 3) the percentages of displacement loss of the surrounding rock at the crown are different in different directions, with 21.42% in the horizontal direction and more than 40% in the vertical direction; and 4) the deformation rate is relatively large—within the scope of 1.0 times the tunnel diameter before and after it passes through the monitoring section—with the vertical displacement being 70% of the total settlement. 2018 Vol. 55 (1): 114-123 [Abstract] ( 884 ) [HTML 1KB] [ PDF 3186KB] ( 1746 ) 124 On Calculation Formula of Existing Metro Tunnel Displacements Induced by Adjacent Foundation Pit Excavation WEI Gang ZHAO Chengli Considering the unloading stress due to excavation at the bottom and sides of a foundation pit and the shielding effect of the retaining structure at the bottom, a semi-analytical and semi-empirical method is proposed based on the Mindlin formula. A calculation formula for the displacement of an existing metro tunnel caused by excavation of an adjacent foundation pit is deduced, and effects of the foundation pit size, change of relative position to the tunnel and reinforcement measures on existing metro tunnel displacements are analyzed. Results show that the horizontal and vertical displacements of a tunnel increase with an increase of the tunnel overburden, and the displacement increases obviously with a decrease of the clear distance between the foundation pit and the tunnel. Increasing the excavation length of the foundation pit has little effect on tunnel displacement, while the excavation width and depth of the foundation pit have an obvious effect on tunnel displacement. Finally, the effect of reinforcement and control measures could be considered; and the maximum horizontal displacement of the tunnel decreases linearly with a decrease of the stress loss ratio of the retaining structure of the foundation pit, but the vertical dis? placement of the tunnel hardly changes. 2018 Vol. 55 (1): 124-132 [Abstract] ( 840 ) [HTML 1KB] [ PDF 3256KB] ( 1671 ) 133 Effects of Different Twin-Tunnel Excavation Overburdens on the Bearing Capacity of an Adjacent Pile Group SHAO Yu1,2,4 LIU Ying2,3 JIANG Jie2,3 MA Shaokun2,3 XIE Qi2 The bearing capacity of a pile group is inevitably effected by adjacent tunnel excavation. In this paper a centrifugal model test is described, and a back analysis of the mechanical and physical parameters of soils is conducted regarding test results and based on the displacement control method (DCM) for the ground loss ratio. Further analysis on some typical cases is performed by numerical simulation with respect to different relative positions between the tunnel and pile group. Results show that twin-tunnel excavation has obvious effects on the pile top settlement if the pile groups are all above the tunnel sides: for instance, the pile top settlement can reach 5.51% dp (diameter of a single pile) when the ratio of the overlying overburden depth (C) and tunnel diameter (D) is 3.7. When the tunnel bottom is flush with the pile bottom, the bearing capacity of the pile group increases after twin-tunnel excavation compared to that of a tunnel within the scope of the pile body and at the bottom of the pile end. The load transfer mechanisms of various piles of the pile group are similar to those of the friction and end bearing pile when the tunnel axis is within the scope of the pile body, while it is similar to the end bearing friction pile when the tunnel axis is be? low the pile end. 2018 Vol. 55 (1): 133-139 [Abstract] ( 863 ) [HTML 1KB] [ PDF 3214KB] ( 1564 ) 140 Metro Operation-Induced Dynamic Response of Foundation Soil for Different Degrees of Consolidation CHEN Yun1,2 DING Zhi2 WEI Xinjiang2 GE Guobao3 ZHOU Lianying2 During metro operation, soil disturbance occurs due to interaction of the train load and the track system. A vertical vibration model of the train load is established, and the law of load varying with time at the tunnel invert is calculated. The vibration response of the foundation soil to a train running on the Hangzhou Metro line 1 under construction effect is analyzed using three-dimensional FEM. The results show that: 1) ground surface vibration lags and vibration strength decreases gradually with an increase of distance between the surface soil mass and the tunnel central line; 2) on the tunnel′s longitudinal axis, the vibration laws of foundation soils above and below the tunnel have certain differences; and 3) the smaller the initial consolidation degree, the larger the ground surface vibration response, while the soil mass underneath the tunnel is affected slightly by construction disturbance. It is significant to consider the effects of metro construction disturbance in order to rationally analyze environmental vibrations during metro operation. 2018 Vol. 55 (1): 140-147 [Abstract] ( 804 ) [HTML 1KB] [ PDF 3368KB] ( 1771 ) 148 Calculation Model of the Uplift Movement of a Shield Tunnel during Construction in Soft Soil WANG Daoyuan1,2,3 YUAN Jinxiu1 ZHU Yongquan2,3 SUN Minglei2 ZHU Zhengguo2 The uplift mechanism of a segment is analyzed, and the load distribution law of a calculation model for segment uplift during shield tunnel construction is determined. There are some problems if the elastic support method and modified routine method are directly applied to the design of a shield tunnel during uplifting: calculations by the elastic support method show that segment bottom moves downward and doesn′t conform to the actual conditions of segment uplift, while the modified routine method doesn′t consider the reverse compress characteristics of the overflying soil mass at the tunnel crown. Based on the elastic support method and thoughts of a modified routine method, a mechanical model of reversal resistance is set up. The results show the proposed calculation model agrees very well with the characteristics of segment uplift during construction. The maximum and minimum values of the bending moment, axial force and shear force under the state of segment uplift during construction increase by 68%,21%, 51%, and 34%, 69%, 22%, respectively, compared with the elastic support method and modified routine method, which shows that segment damage and cracking or leaking caused by inadequate reinforcement can be avoided with the proposed design method for an uplift segment. 2018 Vol. 55 (1): 148-155 [Abstract] ( 855 ) [HTML 1KB] [ PDF 2213KB] ( 2082 ) 156 Analysis of the Dynamic Influence of Aircraft Load on a Tunnel Structure SUN Xiaojing1 TAN Zhongsheng1 ZHOU Sizhen2 FENG Hongxi1 CHAO Kai1 With the development of the three-dimensional traffic network, there are tunnels being constructed un? derneath airport runways and aprons, and it is necessary to study the effects of the moving load of an aircraft on the underlying tunnel structure to guarantee stability. Using the Beijing Capital Airport MRT as an example, the effects of the aircraft's moving load upon a tunnel structure are studied by comparing two response results of simplified aircraft moving loads (node dynamic load and surface load) by FEM. The results indicate that: 1) the variation laws of tunnel′s vertical displacement under the two simplified aircraft loads are similar, but the vertical displacement is slightly larger under the node dynamic load; 2) variation of the relative position of the aircraft′s landing and the tunnel has little effect on the vertical displacement variation law of the tunnel structure; 3) the dynamic influence on the tunnel structure is obvious when the plane is within the scope of a runway that measures triple the tunnel diameter and is located right above the tunnel—not only does it cause apparent vertical displacement of the tunnel structure,but it also results in a significant increase of the pressure on the surrounding rock; and 4) the pressure on the surrounding rock and the vertical displacement at the center of the tunnel crown are the highest, and therefore require much attention. 2018 Vol. 55 (1): 156-163 [Abstract] ( 905 ) [HTML 1KB] [ PDF 2900KB] ( 1732 ) 164 On Water Burst in Deep-Buried Tunnelling Based on Hydrofracturing Method WANG Junxi LI Qiong WU Weixiong TAO Hu LI Xingtian YANG Zhiguo SHI Xi Water burst events are the chief disasters encountered during tunnel excavation. The progress of re? search on water burst in deep-buried tunnels by hydrofracturing theory is briefly introduced. In light of the mechanism of hydraulic fracturing, the role of multi-physics coupling should be considered in study of water burst disasters. Based on Biot's consolidation theory, the concept of damage is applied, and the dynamic evolution of rock mass permeability is considered. The possibility of a water burst can be assessed by analyzing permeability change as a result of changes to rock's mechanical conditions during advance of the working face. The results show that rock mass damage and failure induces permeability change, which makes way for a water burst and increases its possibility. A strong permeable zone, like the fractured zone, is a precondition of a water burst, and a high hydraulic gradient is the original source of a water burst. 2018 Vol. 55 (1): 164-169 [Abstract] ( 706 ) [HTML 1KB] [ PDF 1742KB] ( 1871 ) 170 Hydraulic Characteristics and Stability Analysis of an Immersed Tunnel Element during Floating Transportation in an Inland River WU Gang1 SHEN Yongfang1 SUN Hong2 In light of the characteristics of floating transportation for elements of an immersed tunnel in an inland river, an element-floating motion model and a cable tension calculation model are established and hydraulic calculation formulas for floating transportation are given. The floating transportation of elements in still water and water with different flow rates and different flow angles are simulated and calculated. The floating state and stability of elements during floating transportation are analyzed for a certain freeboard. Results show the established model is applicable to simulating the hydraulic characteristics and stability analysis of an immersed tunnel element during floating transportation in an inland river. The flow rate and flow angle have significant effects on the amplitude and frequency of the swing and the first roll of elements during floating transportation, and transporting elements in a crossflow direction should be avoided as much as possible. 2018 Vol. 55 (1): 170-177 [Abstract] ( 805 ) [HTML 1KB] [ PDF 2096KB] ( 1787 ) 178 A Calculation method of slurry volume-weight during trenching construction of a diaphragm wall based on the stability of slot wall CUI Genqun1 LIU Yao2 Based on the limit equilibrium method, mechanical models for the overall stability and local stability of a slot wall are established, calculation formulas for the critical slurry volume weight values are derived to guarantee stability of the slot wall during trenching construction, a design method for the slurry volume weight is obtained on basis of slot wall stability during trenching construction of the diaphragm wall and a case application is carried out.The results show that the proposed calculation method for slurry volume weight is reliable and it suggests that slurry volume weight calculations under considering local stability of the slot wall should be taken when the similar project locates in loose strata with sand and pebbles. 2018 Vol. 55 (1): 178-183 [Abstract] ( 796 ) [HTML 1KB] [ PDF 1745KB] ( 1689 ) 184 Disturbance Mechanism of Deep-Hole Grouting for Shallow Metro Tunnels in Water-Rich Sand Layers SUN Lianyong1 HUANG Yongliang1 YIN Changfeng1 XU Congjie2 LIU Tao3,4 Regarding the deep-hole grouting reinforcement measures for sand gushing and water inflow during con? struction of a Qingdao metro tunnel passing through a water-rich sand layer, the disturbance mechanism of deephole grouting reinforcement for construction of metro tunnels under these conditions is studied by FLAC3D numerical calculation and site measurement. Grouting depth and pressure should be determined properly since they have a significant effect on ground disturbance and deformation, and a grouting pressure of 1.4~1.5 MPa should be used for the water-rich sand layer in Qingdao. When the ground surface keeps heaving, the surface above the double-tube tunnel heaves in an "M" shape, the grouting pressure at the tunnel′s central line has an obvious effect on ground disturbance, and the maximum heaving occurs at the tunnel crown. The ground surface heaves rapidly at the early stage of grouting and subsides quickly when the working face is within a scope of -3D in front of the monitoring section, then the ground settlement slows down within a scope of -2D and gets faster within the scope of 1D after it passes through the monitoring section, finally it tends to be stable. The effects of grouting construction on a building is less compared to that of surface uplifting, and a building above the tunnel deforms in a positive curvature with the occurrence of ground deformation in an "M" shape; a reversed splayed crack occurs at the building wall when the building structure is damaged. Additionally, crown settlement and clearance convergence are fast when working face passes through the monitoring section and tend to decrease when it is within 2D scope away from the monitoring section,then stabilizes gradually within a scope of 3D. 2018 Vol. 55 (1): 184-193 [Abstract] ( 848 ) [HTML 1KB] [ PDF 4593KB] ( 1958 ) 194 Structure Deformation Caused by Shield Tunnel Excavation Above Existing Tunnels of Shenzhen Metro JIANG Hua1 YIN Minglun1,2 JIANG Yusheng1 SUN Zhenyang1 WU Quanli2 With the rapid development of subway network, it is more and more common for shield tunnels to pass through existing adjacent tunnels. The effect of adjacent shield tunnel construction on existing underlying tunnels is more complicated than ordinary metro tunnel construction. Based on the special construction condition of two-tube shield tunnel of Shenzhen metro line 9 overlapped above the existing two-tube tunnel of Shenzhen metro line 1, the laws of horizontal and vertical deformation of existing tunnel tubes induced by new shield tunneling are studied by numerical simulation and in-situ automatic monitoring, and the influence of earth pressure on the deformation of existing tunnel tubes is analyzed. The results show the in-situ automatic monitoring data basically comply with that of the numerical simulation; the effects of the excavation of the first new tunnel tube on existing tunnel tubes are larger than that of the second tube. The existing tunnel tubes generally uplift in the vertical direction, with a maximum accumulative uplift volume of 2.2 mm. The horizontal deviation of existing tunnel tubes complies with the direction of the shield driving, with the maximum horizontal deviation around 1.4 mm. The effect of the earth pressure on horizontal displacement of existing left and right tubes is roughly the same, and the horizontal displacement increases with an increase of earth pressure. Additionally, the effect of the earth pressure on the vertical displacement of the existing left and right tubes is different: the uplift volume of the left tube decreases with an increase of the earth pressure while the uplift volume of the right tube increases with an increase of the earth pressure. 2018 Vol. 55 (1): 194-202 [Abstract] ( 787 ) [HTML 1KB] [ PDF 4599KB] ( 2062 ) 203 Establishment of a Ventilation Network and the Shaft Ventilation Effect in a Large Underground Cavern Group ZHANG Heng1 LIN Fang1 ZHANG Kai1 YANG Jiasong2 CHEN Shougen1 Large underground cavern groups are usually built in stages, and forced ventilation is often adopted during construction of the upper part. The air duct and air supply must be improved in order to maintain forced ventilation during construction at the middle and lower parts due to a more serious pollution source compared to the upper part.However, it′ s not feasible to increase the air supply volume that is restricted by the size of the construction adit,which results in deterioration of ventilation conditions. Based on the construction ventilation case of the Jinzhou underground oil storage cavern, the shaft ventilation effect is studied and a further study of the effects of the shaft diameter, location, and depth on construction ventilation is conducted by Fluent calculation software and field measurements. The results show that the shaft diameter has a certain influence on the cavern′s ventilation, but the effects of ventilation enhancement are limited by changing the shaft diameter; the ventilation effect is closely related to shaft depth, and the optimal shaft depth is 70 m; with the forcing of fresh air by the axial flow fan installed at the shaft mouth and entrance of the construction adit (transportation passage leading to the cavern from the surface) used as an exit for polluted air, an orderly virtuous axial ventilation network could be formed. 2018 Vol. 55 (1): 203-209 [Abstract] ( 782 ) [HTML 1KB] [ PDF 3726KB] ( 1698 ) 210 Parameters for Pipe Roof Support of Shallow Bored Tunnels ZENG Runzhong1 ZHAN Tao2 YANG Chengzhong1 Based on the pipe roof advance support of a certain shallow bored tunnel, the application theory of pipe roof parameters is analyzed. Using a stiffness reduction model, the pipe roof layer is converted into an isotropic reinforcement body, a numerical simulation is conducted for the effects of single-and double-layer pipe roof advance reinforcement, and a comparison with monitoring data is carried out. An analysis of the reinforcement effects of a pipe roof with different diameters is undertaken. The results show that the internal force of the initial support and temporary support decrease with an increase of the pipe roof diameter, and surface settlement therefore decreases. 2018 Vol. 55 (1): 210-215 [Abstract] ( 852 ) [HTML 1KB] [ PDF 1523KB] ( 1964 ) 216 Contrast and Application of the Hollow Inclusion Stress Relief Method and Acoustic Emission Method to the In-Situ Stress Measurement in Tunnels with Rockburst Hazards QI Xiaohan1 ZHANG Dongming2 For construction of deep extra-long tunnels with a hazard of rock burst, it is significant to take accurate measurement of the geostress for analyzing rock mass stability and rock burst potential. The principles, calculation method and application procedures of geostress measurement using a hollow inclusion stressometer are introduced in detail, especially the problems that happen often in the course of site measurement. Hole drilling and equipment installation are improved, which effectively increases measurement efficiency and avoids equipment loss. Tests and comparisons of the geostress are carried out for the surrounding rock of the Micangshan tunnel using the hollow inclusion stress relief method and the acoustic emission method, with the results showing the stress magnitude and direction measured by these two methods are very close. 2018 Vol. 55 (1): 216-223 [Abstract] ( 742 ) [HTML 1KB] [ PDF 2777KB] ( 1720 ) 224 Laboratory Study of the Foaming Agent Used for EPB Shield Tunnels PENG Lei1,2 HE Wenmin1,2 CHANG Yawen3 KONG Lingchang3 NING Bo1 LUO Jianhua1,2 In light of the technical requirements of soil mass conditioning for EPB shield tunnel construction, re? search of a new foaming agent formula is conducted. A high-speed mixing method is adopted to choose the proper surface active agent, SDS is determined as the main foaming agent, and SDS is formulated again using AES. The test results indicate that good foam stabilizing effects are obtained if the foam stabilizer dodecanol with a concentration of 0.2 g·L-1 and cationic guar gum with a concentration of 0.04 g·L-1 of high molecular polymer are added when the SDS/AES proportion is 6∶4 and the general concentration is 3 g·L-1. An economical and environment friendly laboratory formula for a foam agent with good foamability and stability is determined, a concentration adjustment is conducted, and the following formula for the finished foam agent is established: 6.82%SDS+4.51%AES+0.57% dodecanol +0.2% cationic guar gum +87.9% water. Compared with other products at home and abroad, this new type of foam agent is an improvement in terms of performance index and economy. 2018 Vol. 55 (1): 224-230 [Abstract] ( 714 ) [HTML 1KB] [ PDF 1582KB] ( 1971 )

More>>   · · More>>

Copyright © 2011  Editorial By MODERN TUNNELLING TECHNOLOGY Supported by:Beijing Magtech Co.ltd  Email:support@magtech.com.cn