[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   2014 Vol.51 Issue.1 Published 2014-02-25 Article 1 Safety Risk Management System for the Cosntruction of Urban Rail Transit Projects Yang Shucai Aimed at the urgent problem of safety risk management of urban rail transit engineering, and based on theoretical analysis, this paper summarizes the experience gained by international cases combining traditional risk management with modern information technology. A synthetic, dynamic management-control model, guaranteed by safety risk management, technical standard, and real-time monitoring systems, is established, realizing a transformation from traditional accident handling to modern risk prevention. The practical application of the research results has verified this model's applicability, feasibility, and scientific validity. 2014 Vol. 51 (1): 1-7 [Abstract] ( 2746 ) [HTML 1KB] [ PDF 0KB] ( 593 ) 8 Mechanism of Collapse and Countermeasures Used During Construction of a Shallow-Buried Tunnel of the Beijing Metro Hu Yongli Using the handling of a collapse in a shallow-buried tunnel of the Beijing metro as an example, the topics of engineering geology, hydrogeology, and metro construction in Beijing are presented. The action mechanisms of the collapse incentives, such ashydrogeology, construction behavior, underground pipelines, and vibrating load are analyzed, deepening the understanding of the collapse-forming mechanism in shallow-buried tunnels. The countermeasures are summarized from the two aspects of collapse prevention and collapse treatment, providing a reference for similar projects. 2014 Vol. 51 (1): 8-15 [Abstract] ( 2326 ) [HTML 1KB] [ PDF 0KB] ( 570 ) 16 Blasting Safety Management Mode for a Shallow Urban Tunnel GAO Jian-Huan-1, ZHAO Xiao-Lei-2, WANG Sheng-Jie-2, WU Lin-Song-2 The blasting of a shallow urban tunnel will have an impact on, and even cause damage to, the surrounding building facilities. Regarding the construction of the Dalian Metro tunnel, characterized by a long blasting schedule, frequent detonating, and many companies and buildings needing protection, this paper expands upon the safety management utilized during tunnel blasting, analyzes the problems associated with monitoring and managing the blasting, and presents corresponding countermeasures. 2014 Vol. 51 (1): 16-20 [Abstract] ( 2386 ) [HTML 1KB] [ PDF 0KB] ( 543 ) 21 A Study of Geological Structures Inclined to Disaster and Models of Water Burst in Deep-Buried Long Tunnels LUO Xiong-Wen-1, HE Fa-Liang-2 Water bursts are one of the most serious geological disasters that can occur during the construction of long deep-buried tunnels, and their occurrences are closely related to the aquifer ahead of the working face or outside the free face. In this paper, the causes of water burst occurrences in long deep-buried tunnels are analyzed. Five kinds of structures and models are systematically presented: a highly fractured zone at upper wall of an uncemented and water-rich compressive fault ; an uncemented and water-rich tensional fault zone; an uncemented and water-rich faulted bedding plane (a closely jointed rock mass); water-filling karst; and an underground water-bearing syncline structure and its water burst model. Moreover, disasters that occurred in five kinds of structures are analyzed through examples. 2014 Vol. 51 (1): 21-25 [Abstract] ( 2487 ) [HTML 1KB] [ PDF 0KB] ( 571 ) 26 Analysis of 3D Dynamic Response of Closely Overlapping Tunnels During a Strong Earthquake LI Ji-Dong, Tao-Lian-Jin, Wu-Bing-Lin, An-Jun-Hai, Guo, FEI Using the Beijing Metro line 7 as an example, a numerical model of the closely overlapping tunnels was established by FLAC3D finite difference software and the seismic response characteristics of the tunnels during a strong earthquake were studied by inputting Beijing Hotels horizontal earthquake waves at the model base. The calculations indicate that in the closely overlapping tunnels, horizontal displacement of the uppertunnel is greater than that in the lower tunnel, and the maximum relative horizontal displacements at the tunnel crown of both the upper and lower layer were found to be at the middle overlapping part. Additionally, the maximum acceleration response of the non-overlapping part was found at both the upper tunnel floor and the lower tunnel crown. Compared to the shallow-buried tunnel, the horizontal displacement and stress of the upper layer has a magnifying effect to different degrees, and the peak acceleration is reduced; compared to the deep-buried tunnel, the horizontal displacement of the lower layer has a magnifying effect, while the accelerated speed and the stress is reduced to different degrees. 2014 Vol. 51 (1): 26-31 [Abstract] ( 2494 ) [HTML 1KB] [ PDF 0KB] ( 559 ) 32 Research on Ground Motion Parameter Correction in the Response Acceleration Method DONG Zheng-Fang-1, 2 , WANG Jun-Jie-2 In this paper, the interaction coefficient between structural deformation and free field distortion is used to correct the ground motion parameters in the response acceleration method, for approximately considering the influence of structures on ground motion parameters. The response acceleration method is therefore modified. In order to verify the applicability of this method, it is assumed that a typical circular shield tunnel is the benchmark model under certain geological conditions, and the response acceleration method, the modified method, and dynamic time-history method are then utilized to calculate the structural internal force under different degrees of lining stiffness. Results indicate the accuracy of the response acceleration method can be improved taken the time-history method as the reference, especially for the bending moment. 2014 Vol. 51 (1): 32-37 [Abstract] ( 2675 ) [HTML 1KB] [ PDF 0KB] ( 607 ) 38 On the Particle Vibration Rule of Rock Surrounding a Deeply Buried Circular Tunnel Under a Blasting Seismic Wave 吕Zhen-Li-1 , Sun-Jin-Shan-2, Zuo-Chang-Qun-2 Blasting-induced seismic waves may cause dynamic responses in adjacent tunnels and affect their safety and stability. With numerical simulation, the interaction between a P wave (Seismic Wave) and adjacent circular tunnels was analyzed, and the distribution rule of particle vibration under different working conditions was studied. The results show that when the stress wave is passing through the circular tunnel, particle vibration direction may be slightly deflected near the tunnel wall and the vibration velocity may be greater or less than that of the vibration source, which has an obvious scaling effect. Additionally, the vibration frequency, tunnel dimensions, surrounding rock properties, and wavelength-diameter ratio have a great influence on the scaling effect of the particle vibration. 2014 Vol. 51 (1): 38-44 [Abstract] ( 2607 ) [HTML 1KB] [ PDF 0KB] ( 561 ) 45 A Fuzzy Comprehensive Evaluation of the Seismic Hazard Rule and Relevant Risks for Mountain Tunnel Bodies ZANG Wan-Jun-1, WANG Zheng-Zheng-2 As the tunnel body section is a relatively large proportion of the whole length of a tunnel, seismic risks cannot be ignored. A fuzzy comprehensive evaluation model (FCEM) was established to analyze the seismic risk to the body of a mountain tunnel. Based on data from 59 mountain tunnels damaged by the Wenchuan earthquake in the Sichuan province, 10 influential factors and their relationships to the earthquake were summarized: burieddepth, construction situation, supporting structure and its intensity, section size and shape, seismic intensity, seismic wave direction, epicentral distance, tunnel length, fault and fractured weak zone, and surrounding rock. Furthermore, the analytic hierarchy process was adopted to calculate the weights of influential factors, and a fuzzy calculation was conducted using the trapezoidal and semantic membership function by fuzzy mathematics and weighted average method. FCEM was applied to the Longdongzi tunnel, with the results showing that the seismic risk to the Longdongzi tunnel body is extremely high. 2014 Vol. 51 (1): 45-53 [Abstract] ( 2324 ) [HTML 1KB] [ PDF 0KB] ( 542 ) 54 A Study of the Basic Issues Regarding the Swelling Pressure Analytical Solution for Mountain Tunnels LI Hua-Yun-1, Zhang-Zhi-Qiang-1, Zhang, YANG 1, Chen-Li-Ming-1, Yang, XIANG 2, Zhang-Xiao-Wei-2 The swelling tendency of expansive rock not only results in the obvious manifestation of supporting structure stress and deformation at the construction stage, but also has a long-term "post-loading effect" during the operation stage, which is different from general tunnels. Based on the principle of elastic mechanics, this paper derives the analytical solution of tunnel support structure stress and deformation under different swelling conditions of surrounding rock. It also analyzes the theoretical relationship between the tunnel support structure stress and deformation and their distribution law regarding the variations of the rock swelling rate, structure support rigidity, and rock swelling pressure. Using a project as an example, the finite element method is adopted for verification, and the results prove that this analytical solution has a certain degree of reliability and can provide a basis for tunnel design and construction as well as a long-term safety evaluation for completed structures. 2014 Vol. 51 (1): 54-61 [Abstract] ( 2735 ) [HTML 1KB] [ PDF 0KB] ( 554 ) 62 On the Mechanism of Controlling Deformation of Weak Surrounding Rock with a Pre-Arch DU Lin-Lin, Wang-Xiu-Ying, Liu-Wei-Ning Deformation of weak surrounding rock mainly occurs in front of the working face and the key point it is to control the deformation in front of the working face, i.e. pre-convergence. The pre-arch is characterized by good transverse continuity and rapid construction, and thus has positive effects on controlling the pre-convergence of weak surrounding rock. A 3D numerical model was set up by FLAC3D and the mechanism of the pre-arch to control deformation of weak surrounding rock was analyzed. Studies show that: (a) The pre-arch can effectively control the pre-convergence, convergence, and rock deformation above the tunnel. As rock conditions worsen, the effects of the pre-arch are more significant; (b) The pre-arch can effectively control the stress relief of the rock mass ahead of the working face and control the developing range of the collapsing arch above the tunnel, limit the distributing area of the collapsing arch at the tunnel crown, reduce the disturbance on surrounding rock, and restrict stress redistribution; and (c) Since stress relief is controlled, the rock load applied on the pre-arch is larger than that of conventional support. 2014 Vol. 51 (1): 62-69 [Abstract] ( 2266 ) [HTML 1KB] [ PDF 0KB] ( 551 ) 70 A Study of Stress Evolution During Construction of Extra-Large Cross Section Railway Tunnels ZHAO , Bin, Zhang-Hui-Jian, Chou-Wen-Ge In order to study the stress evolution of a rock mass during tunnel construction, the curve, reflecting the three-dimensional stress of the rock mass, was utilized in combination with the Mohr-Coulomb criteria to demonstrate the stress path and define the safety factor. In this paper, using the Wumenshan Tunnel 2 as an example, FLAC3D software is applied to analyze the evolution of the stress path and safety factor during construction of an extra-large cross section railway tunnel. Results show that during construction of extra-large cross section railway tunnels, the following are true: the evolution of the stress path and safety factor of the rock mass at both sides of the tunnel acts with a certain degree of symmetry during partial construction; while advanced to monitoring points spaced at 3m, the stress value and safety factor at the monitoring points are sharply decreased due to excavation and the deflection of the principal stress takes place; after the completion of the primary support, the stress value and safety factor are certainly increased and tend to be stable; earlier installation of all primary supports is useful to control the evolution of rock stress; the safety factor at the sidewalls is less than 1.0 for a long time, to which more attention shall be paid; when the working face passes through each monitoring point, the safety factor measured at each monitoring point tends to be stable and more than 1.0, which shows the tunnel construction is safe based on this computation. 2014 Vol. 51 (1): 70-76 [Abstract] ( 2615 ) [HTML 1KB] [ PDF 0KB] ( 575 ) 77 Determination and Application of the Support Resistance of Surrounding Rock Around Deep Tunnels CHU Ming-Xiang The support resistance of surrounding rock in deep tunnels is determined by the pressure and displacement of surrounding rock obtained by theoretical calculations and the relationship between the support and displacement analyzed by the P-U figure. The range of the support resistance can be determined based on the quantitative calculation of pressure and displacement of the surrounding rock of the deep tunnel, and the support scheme and schedule can be selected considering the relationship between the surrounding rock and support in the P-U figure. This method has been applied to the support of the pump chamber of the Longgu coal mine, and the results show that : (1) The calculated pressure and displacement of the surrounding rock conform with engineering practice and the reasonable range of support resistance of a pump chamber is 4 ~ 6MPa; (2) The support scheme and schedule can be determined based on the support resistances and P-U figure; (3) The achievements have been successfully applied to coal mine engineering. 2014 Vol. 51 (1): 77-81 [Abstract] ( 2343 ) [HTML 1KB] [ PDF 0KB] ( 547 ) 82 Analysis of Lateral Slope Stability During Construction of a Loess Tunnel with a Large Section CHEN Si-Yang-1, 2 , ZHU Yan-Peng-1, 2 , LI , ZHONG 1, 2 , HUANG Li-Hua-1, ZHANG Hao-Liang-1 For a loess tunnel with a large section passing through a lateral slope, some engineering risks like landslide or collapse are easily induced by tunneling construction, which frequently disturbs the soil mass. Based on a test section of a specific project, the lateral slope was reinforced before tunnel construction. With stability calculation for the lateral slope and using the improved strength reduction method, as well as reductions to the tensile strength index and shear strength index, the impacts of the three tunneling methods of short bench, CD, and CRD on lateralslope stability were simulated and analyzed using the FLAC3D numerical model. Engineering practice shows that the analytical results by improved strength reduction method generally agree with the actual ones under the condition of the undefined potential sliding surface of the lateral side slope, the effects on stabilityof the lateral slope is evident under continuous excavation, and the CRD method is most suitable for the construction of a unsymmetrical loading loess tunnel with a large section once the lateral side slope is reinforced. 2014 Vol. 51 (1): 82-89 [Abstract] ( 2653 ) [HTML 1KB] [ PDF 0KB] ( 524 ) 90 Fluid-Solid Coupling Analysis for Foundation Pits in Soft-Soil Areas NIU Shuang-Jian-1, 2 , 3 , YANG Da-Fang-2, LIN Zhi-Bin-3 Considering the fluid-soil coupling effect among a group of deep foundation pits and using the Shenzhen Metro line 5 as an example, a numerical simulation of the fluid-solid coupling of a group of foundation pits in soft soil was carried out. The results show that: (1) A higher underground water level results in greater deformation of the foundation pits, with an exponential relationship between the underground water level and the maximum values of both surface subsidence and bottom heave, and a linear relationship between maximum horizontal displacement of the fender pile and underground water level; (2) Existing station have a reinforcing effect on the soil body of new foundation pits at the side of the station, which decreases the soil deformation at the side closest to the station and increases it on the other side; (3) Regarding the numerical analysis considering the fluid-solid coupling action of foundation pits, the simulation complies with practical experience. 2014 Vol. 51 (1): 90-96 [Abstract] ( 2206 ) [HTML 1KB] [ PDF 0KB] ( 538 ) 97 Numerical Simulation of the Rockburst Mechanism in the Meihuashan Tunnel ZHANG Yi-Yu-1, Xing-Bo-Rui-2, Song-Cheng-Ke-3 Affected by staged excavation, stress-strain nonlinear variation may occur inside the surrounding rock of a tunnel. In high-ground-stress areas, this mechanical effect tends to be even more obvious and can cause serious geological disasters like rockbursts and wall caving, etc. Taking the construction of the Meihuashan tunnel in Fujian as an example, this paper analyzes the interaction of the excavation steps and the change rule of the 3D stress field and strain field in the tunnel by establishing a 3D excavation numerical model with 3D-Sigmasoftware, using the measured stress data as a boundary condition and determining the inputs of the rock mass with the Hoek-Brown strength criterion. The results show that: because of high ground stress, compressive stress concentration occurs at the tunnel crown and shear stress concentration occurs at the spandrel, which may cause brittle failure at the tunnel wall; previously excavated tunnel sections may be affected by subsequent excavation, making the stress concentration effect more obvious and the failure of the surrounding rock more serious; the actual rockburst locations correspond with the locations of maximum compressive stress concentration and maximum shear stress concentration in simulation analysis. The numerical simulation can clearly reveal the mechanism and the possible law of the rock burst, providing strong technical support for engineering applications. 2014 Vol. 51 (1): 97-104 [Abstract] ( 2403 ) [HTML 1KB] [ PDF 0KB] ( 574 ) 105 Model of Chloride Ion Erosion in Segment Concrete Considering Variable Diffusion Coefficients LI , ZHI 1, 2 , Peng-Li-Min-1, Shi-Cheng-Hua-1 By analyzing the mechanism of chloride ion erosion in concrete segments, andbased on the Fick second diffusion law, the chloride ion erosion model with variable diffusion coefficients was set up , in which the time, and diffusion depth were taken into consideration comprehensively. The effectiveness and reliability of this model was verified by an analysis of experimental data concerning the anti-erosion performance of tunnel segments. Compared to the conventional Fick second diffusion law model considering constant diffusion coefficients, this model can not only reflect the development trend of chloride ion erosion of the structure itself and the chloride ion concentration in concretes at various depths, but also predict the chloride ion content in different phases or at various depths. Furthermore, it can predict when corrosion will occur in reinforcements. 2014 Vol. 51 (1): 105-109 [Abstract] ( 2312 ) [HTML 1KB] [ PDF 0KB] ( 532 ) 110 On Temperature Field Variation of the Surrounding Soil Mass Caused by Artificial Single Pipeline Freezing WANG Zhi-Liang-1, Shen-Lin-Fang-1, Xie-Jian-Bin-2 A phase-transition temperature field model of artificial freezing was established to study the transient variation of the temperature field of a surrounding soil mass being divided into a frozen zone and a cooling zone. A phase-transition heat conduction equation of single pipeline freezing was solved with variable substitution, and an analytical expression of transient variation of the temperature of soil mass was derived, which is indicated by exponential integral function. Using finite terms of exponential integral function series expansion, analytical expressions for the temperature field distributions of both the frozen zone and cooling zone around the frozen pipe were obtained. The effects on the artificial freezing temperature field caused by temperature differencesin frozen soil mass, heat absorption coefficients of frozen pipes, and the latent heat of frozen soil masses per unit volume are discussed based on a specific case. The results prove that: (1) the greater the temperature difference of the frozen soil mass, the slower the frozen front radius develops; (2) the larger the heat absorption coefficient of the frozen pipe, the faster the frozen front radius develops; and (3) the smaller the latent heat of the frozen soil mass, the faster the frozen front radius develops. The above three influential factors have a linear relationship with the development of the frozen front radius. 2014 Vol. 51 (1): 110-116 [Abstract] ( 2328 ) [HTML 1KB] [ PDF 0KB] ( 572 ) 117 Analysis of Factors Affecting Intersected Tunnel Construction LI Yu-Feng-1, 2 , Lei-Ming-Feng-1, Lu-Gui-Qing-2, Huang-Guo-Fu-2 Considering the three factors of rock classification, crossing angle, and rock pillar height, 100 cases were assumed to implement numerical modeling calculation and the law of the three factors affecting construction of intersected tunnels was discussed regarding crown settlement and internal force change of the primary support in an existing tunnel. Study results show that crown settlement and shotcrete axial force present a trend of significantly increasing with the enlargement of the crossing angle. When the rock pillar height increases and rock mass is poor, the induced crown settlement of the existing tunnel becomes larger while the increasing rate of the shotcrete axial force becomes smaller. The structural deformation of existing tunnels can be used as a key review indicator during the design and construction of intersected tunnels. 2014 Vol. 51 (1): 117-123 [Abstract] ( 2851 ) [HTML 1KB] [ PDF 0KB] ( 608 ) 124 Comprehensive Fuzzy Evaluation of the Safety of Existing Buildings During Tunneling Construction in Urban Areas KONG Wen-Tao-1, HE Ya-Bo-1, LI , QI 2, WANG , HAO 3, QIN Wei-Min-3 Generally, bored tunnels in urban areas are characterized by a shallow depth, a large section, poor surrounding rock, dense buildings above the tunnel, and high-risk construction. Aiming at the safety risk to existing buildings during tunneling construction, the three influential factors of building performance, tunnel condition, and in-situ monitoring data are considered and a two-level fuzzy comprehensive model is established to dynamically evaluate the safety of existing buildings and determine reasonable safeguarding measures for buildings according to evaluation consequences. Using the case of the Wushancun tunnel passing under existing buildings on Chenggong avenue in Xiamen, construction safety was evaluated and relevant measures were adopted according to evaluation consequences, and sound results were achieved. 2014 Vol. 51 (1): 124-129 [Abstract] ( 2350 ) [HTML 1KB] [ PDF 0KB] ( 547 ) 130 The Numerical Simulation of a Mined Tunnel Passing Existing Structures ZHANG Zhi-Yong During metro construction, the problems arising from the excavation of mined tunnels passing existing structures have drawn more and more attention. Based on the construction of the Daguanying station of the Beijing metro line 7 and the principles of stratum-structure interaction, this paper simulates the construction of a mined tunnel passing 4 small existing pilot headings and analyzes the influences of the construction on the deformation, stress of the pilot headings, surface settlement, and nearby pipelines. It is concluded that the construction creates an obvious disturbance of the existing structures and after the reinforcement of the passing sections, the deformation of the pilot headings, stress concentration on both sides, and surface settlement are well controlled. 2014 Vol. 51 (1): 130-137 [Abstract] ( 2396 ) [HTML 1KB] [ PDF 0KB] ( 547 ) 138 Comparison and Analysis of Temporary Support Schemes for the Middle Pilot Heading in a Multi-Arch Loess Tunnel YU Yuan-Quan-1, Liu-Xiao-Lin-2, Zhang-Xue-Fu-2 When the bench method is used for the excavation of a multi-arch loess tunnel, steel rib support and backfill support are commonly used for the temporary support of the middle pilot heading. Using the Qingliangsi multi-arch tunnel on the Taiyuan-Jiaxian Expressway as an example, a comparative analysis of overall elastic-plastic simulation was carried out for those two kinds of supporting methods in order to select the most logical temporary support. The results show that the steel rib and backfill supporting methods have the same supporting effects on the surface displacement, crown settlement, and bolt axial force , and both of them can meet the requirements for tunnel deformation. However, the support provided by steel ribs in terms of the surrounding rock stress, initial support stress, and bolt axial force is better than that provided by the backfill support. 2014 Vol. 51 (1): 138-143 [Abstract] ( 2535 ) [HTML 1KB] [ PDF 0KB] ( 537 ) 144 Study of Segment Floating During Shield Tunneling in Soft Soil Stratum WANG Qi-Yan-1, Yang-Jian-Hui-2, Xue-Yong-Li-1, Chen-Zi-Hai-1 Based on in-situ monitoring and analysis of one metro project in Hangzhou, segment floating can be divided into primary floating and secondary floating with the primary floating taking up a larger proportion, from 50% to 80%. Combined with shield construction at this section, Abaqus finite element software was applied to analyze the segment floating in soft soils. Results show that segment floating is divided into three stages: the surging stage, the gentle development stage, and the stabilizing stage. Additionally, the laws of segment floating, along with the resilience of underlying soils at the segment bottom and settlement of overlying soils on the segment top varying with the grouting pressure, grout elasticity modulus, earth pressure in the soil chamber, and jack pressure were obtained. 2014 Vol. 51 (1): 144-152 [Abstract] ( 2900 ) [HTML 1KB] [ PDF 0KB] ( 526 ) 153 GPR Forward Simulation of Filled Karst Caves in Advance Geological Prediction for Tunnels LIU , WEI 1, Zhou, BIN 2, Gan-Fu-Ping-1, ZHAO , WEI 1 Unfavorable geologic bodies such as karst caves often turn up during tunneling. Based on different fillers, karst caves are classified into four types: air-filled, water-filled, silt-filled, or grit-filled. Applying the principles of the finite difference time domain method (FDTD), a forward simulation for common karst diseases was performed, and the results of the theoretical simulation were verified using project cases. The results show that the essential feature of forward simulated images of karst caves is a hyperbolic event. From the kinematics and dynamical characteristics of the hyperbolic event, we can infer the geometric position of karst caves and qualitatively determine what their fillers are. The simulated results are in agreement with the measured ones. 2014 Vol. 51 (1): 153-158 [Abstract] ( 2314 ) [HTML 1KB] [ PDF 0KB] ( 512 ) 159 Numerical Simulation of Geological Radar Detection for Unfavorable Geologic Bodies at the Tunnel Floor HAN Hao-Dong, DING Jian-Fang, GUO Ru-Jun Ground penetrating radar (GPR) plays an important role in detecting unfavorable geologic bodies at the bottom of tunnels. The response characteristics of various unfavorable geologic bodies reflected in radar images are the foundation of effective detection. By establishing a geoelectric model of the complex geology at a tunnel bottom, a numerical simulation was carried out by the finite difference time domain method (FDTD) and GPR images of the different geological conditions of karst, faults, and fracture zones were analyzed, providing a basis for the accurate interpretation of GPR images. The accuracy of GPR applied in detecting unfavorable geological bodies at the tunnel floor is determined using the case of a specific tunnel on a passenger-dedicated line. 2014 Vol. 51 (1): 159-163 [Abstract] ( 2716 ) [HTML 1KB] [ PDF 0KB] ( 493 ) 164 Experimental Study on the Reserved Space Method for Tunnels in Soft Rock with High Ground Stress ZHANG , MEI 1, Huang-Hong-Jian-2, Zhang-Min-Qing-3, Xiao-Guang-Zhi-3, Ren-Cheng-Min-3 Many tunnels on the Lanzhou-Chongqing railway pass through soft rock with high ground stress, where large deformation problems are extremely prominent during tunnel construction. Using the construction of the Maoyushan tunnel as an example, this paper, based on the stress release concept and the reserved space method, reveals the deformation law and stress releasing ability of tunnels in soft rock with high ground stress. The results show that stress release is obtainable by the reserved space method during construction in soft rock with high ground stress, ensuring the safety of the primary lining. As for the flexible protective cover, it may be formed by 4φ22 mm lattice girder and 25 cm shotcrete with wire mesh, with the longitudinal distance between two steel frames being 0.75 m and the reserved space being 30~50 cm. 2014 Vol. 51 (1): 164-170 [Abstract] ( 2455 ) [HTML 1KB] [ PDF 0KB] ( 499 ) 171 Research on the Applicability of ADECO-RS in a Water-Rich Sand Stratum SUN Fu-Feng-1, LIU , TAO 2, LEI , GANG 3 ADECO-RS, i.e. "toroidal horizontal jet grouting pile + advance grouting pipe", is adopted in the Qingdao metro for the reinforcement of a water-rich sand stratum characterized by being soft at the top and hard on the bottom. The pile-forming effect and problems regarding horizontal jet grouting piles for different sand layers are studied through field sampling and observation. The impact of ADECO-RS on construction and the surrounding environment is analyzed by field monitoring and measuring. The results show that the application of ADECO-RS has an obvious positive effect on settlement control, and there are many problems, such as water leakage induced by the misalignment of two piles and ground uplift caused by improper grouting pressure control. In order to overcome these problems encountered during construction, the pile body is controlled both horizontally and vertically, and tracking monitoring is used for the grouting process. The construction results prove the applicability of ADECO-RS for use in water-rich sand strata. 2014 Vol. 51 (1): 171-178 [Abstract] ( 2688 ) [HTML 1KB] [ PDF 0KB] ( 541 ) 179 Analysis of the Influence of Foundation Pit Construction on an Operating Metro Tunnel Based on Field Measurement WEI , Gang-1, Li, Gang-2, Su-Qin-Wei-2 An underground passage passes over the existing shield-driven tunnel of the Hangzhou Metro line 1. Due to the complex geological conditions and surrounding environment of the over-passing section, tunnel deformation has to be strictly controlled. For this reason, control measures like foundation reinforcement and sectional excavation are considered in the tunnel design. Based on the monitoring data from the pile foundation construction and foundation pit excavation, this paper analyzes the rules and characteristics of the vertical displacement, horizontal displacement, and convergence of the shield-driven tunnel at different construction stages. The results show that the pile foundation construction may cause vertical settlement of the tunnel (maximum: 5mm), but has little influence on the horizontal convergence; additionally, foundation pit excavation may cause tunnel floating (maximum: 5mm) and horizontal radial convergence, but has little influence on the horizontal displacement. 2014 Vol. 51 (1): 179-185 [Abstract] ( 2433 ) [HTML 1KB] [ PDF 0KB] ( 515 ) 186 Discussion of Key Construction Techniques for a Shield-Driven Tunnel in a Water-Rich Mixed Ground FENG Huan-Huan, Chen, KUI , Wang-Zhu-Feng, Zhang-He-Pei Water-rich mixed ground is one of the complex geological conditions that may be encountered during shield construction. Using the Dalian Metro line 2 as an example, the construction techniques for shield-driven tunnels are described in respect to shield selection and launching. Considering such difficulties as a small radius, a water-rich fracture zone, and cutter control in hard rock, corresponding countermeasures were adopted concerning the tunnel axis alignment, driving speed control, and cutter management system. Engineering experience proves that the selected shield is suitable for the geological conditions in Dalian and that it is able to adapt to the water-rich mixed ground, therefore meeting relative requirements. 2014 Vol. 51 (1): 186-191 [Abstract] ( 2411 ) [HTML 1KB] [ PDF 0KB] ( 520 ) 192 A Study of Controlled Blasting Techniques for the Multi-Arch Songjiawan Tunne CAI Lu-Jun-1, 2 , MA Jian-Jun-2, Zhu-Yi-Wen-1, Zhou-Da-Hua-3, Liu, SONG 3, Hu-Wu-Zhou-3 The geological conditions encountered during construction of the multi-arch Songjiawan tunnel on theShiyan-Baihe expressway were very complex, and such problems as overbreak, underbreak, an irregular tunnel profile, and cracks on the mid-partition presented themselves during blasting. According to the different surrounding rock classifications, the controlled blasting technique was adopted for this tunnel and the excavation method, blasting parameters, charging structure and priming circuit were optimized to decrease the blasting vibration and improve blasting effects. 2014 Vol. 51 (1): 192-198 [Abstract] ( 2709 ) [HTML 1KB] [ PDF 0KB] ( 551 ) 199 Blasting Control Techniques for an Urban Hard-Rock Tunnel Passing Under Brick-Wood Buildings YANG , Qing-1, Wang-Hai-Liang-1, WANG Jun-Tao-2 A running tunnel of lot 3 of the Qingdao metro line 3 passed under a dental hospital of the First Sanitarium of the Jinan Military Region at a depth of 14m. To minimize the impact from blasting vibrations, large diameter hollow-cylinder cutting and controlled maximum priming charge per delay were used as countermeasures in the excavation. In this way, the vibration velocity of the ground surface was controlled within 1.5cm/s and the safety of the ground buildings and main roads nearby was guaranteed. Meanwhile, using the outer-hole delaying technique, the optimized blasting network reduced the blasting times induced by the detonator segments and shortened the blasting duration, resulting in social and economic benefits. 2014 Vol. 51 (1): 199-202 [Abstract] ( 2627 ) [HTML 1KB] [ PDF 0KB] ( 518 )

More>>   · · More>>

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