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Quick Search     Advanced Search MODERN TUNNELLING TECHNOLOGY   2014 Vol.51 Issue.3 Published 2014-06-25 Article 1 Rock Bolts: An Optimized Ground Support System in Tunnelling WANG Jian-Yu The support effects of rock bolts in tunnelling may be reduced to the concept of ground reinforcement, which features various behaviors in various rock mass structures, with the so-called "suspender effect" being only one of them. As a matter of fact, to confine the function of rock bolts to the suspender effect often leads to a misunderstanding regarding their real support ability. Reinforcement by rock bolts used in various rock mass structures is described and some related problems are discussed concerning the application of rock bolts in China, with recommendations presented as well. 2014 Vol. 51 (3): 1-6 [Abstract] ( 2276 ) [HTML 1KB] [ PDF 0KB] ( 593 ) 7 Construction Scheme of the West Qinling Extra-Long Tunnel on the Lanzhou-Chongqing Railway LI Guo-Liang, SI Jian-Jun, Li-Ning The West Qinling extra-long tunnel, the longest TBM-driven tunnel in China's railway history, is a double-tube single-track tunnel being constructed using a combination of the drill and blast and TBM methods. Based on environmental and hydrogeological conditions, this paper analyzes: a construction scheme comparison; construction characteristics; the engineering adaptability of the TBM, the design of tunnel lining section and its support parameters; the synchronization of lining and TBM driving; and continuous conveyor belt mucking. It also introduces general information regarding the TBM equipment and tunnel construction. 2014 Vol. 51 (3): 7-14 [Abstract] ( 2469 ) [HTML 1KB] [ PDF 0KB] ( 527 ) 15 Statistics and Analysis of Influential Factors of Tunnel Damage Induced by the Wenchuan Earthquake TAO Shuang-Jiang-1, 2 , Jiang-Ya-Jun-1 In order to analyze the influential factors of tunnel damages induced by an earthquake, the relative data of four tunnels seriously affected by the Wenchuan earthquake were collected and analyzed statistically, as well as calculated and verified through ANSYS software modeling. The results show that the main influential factors include the earthquake parameters (earthquake wave peak acceleration), the surrounding rock grade, overburden, faults intersecting with the tunnel, special tunnel structures, and so on. The damage to the lining is more serious if the earthquake wave peak acceleration is high, the rock mass is of a low grade, or the tunnel passes through faults. The damage to the lining is inversely proportional to the overburden depth. Stress easily concentrates at the special structures of a tunnel, resulting in worse damage. 2014 Vol. 51 (3): 15-22 [Abstract] ( 2030 ) [HTML 1KB] [ PDF 0KB] ( 543 ) 23 Exploration of Hygienic Standards for Operation Ventilation of a Highway Tunnel in High-Altitude Area ZHANG Ting-Biao, Zhang-Zhi-Dao sers of the tunnel in high-altitude area always have altitude reaction, which causes the lower tolerance to automobile exhaust emissions. Therefore, as a hygienic standard, the allowable concentration of carbon monoxide in the tunnel also should be lower. While in relevant ventilation specifications, there is no distinction between the high-altitude area and ordinary area regarding the hygienic standards for air in the tunnel. In this paper, the altitude reaction characteristics at different altitudes were converted to the carbon hemoglobin (COHb) saturation equivalence with a standard of COHb saturation which represents the degree of carbon monoxide poisoning, and the suitable values of COHb saturation produced by automobile exhaust CO were proposed in accordance with different highway grades and different tunnel lengths, and corresponding allowable concentration of carbon monoxide was determined considering the time passing through the tunnel. Since the allowable concentration of carbon monoxide specified in current ventilation specifications is somewhat low, sometimes the derived carbon monoxide concentration limit for the tunnel at high-altitude area is higher than that at ordinary elevation, and some analysis were carried out and suggestions were presented for this phenomenon. 2014 Vol. 51 (3): 23-29 [Abstract] ( 2072 ) [HTML 1KB] [ PDF 0KB] ( 506 ) 30 On the Landscape Design of Mountain Highway Tunnel Portals Considering the Psychological and Physiological Behaviors of a Driver YUAN Yu-Lin In light of psychological and physiological behaviors of drivers, this paper discusses design issues regarding tunnel portal shape and ambient landscape with the purpose of reducing risks to drivers entering a tunnel. The results show that the portal shape and ambient environment should be integrated, and it is recommended that the landscape be monotonous and unified. It is necessary to: conceal the surrounding engineering facilities as much as possible to reduce visual distractions, avoid the engraving of tunnel names, decrease the brightness around the tunnel portal, prohibit excessive embellishment, and restrict the use of symbolic portals. 2014 Vol. 51 (3): 30-34 [Abstract] ( 2159 ) [HTML 1KB] [ PDF 0KB] ( 546 ) 35 Application and Experimental Evaluation of Natural Light for Tunnel Illumination WANG Bao-Lin, YE , YING , LIU , CAN , DING , MIN , YAN Bing-Ya On account of saving energy and reducing emissions, an innovative lighting proposal is introduced in which natural light is used for illumination at an expressway tunnel entrance. The natural light is brought into the tunnel entrance by a specially designed daylighting band, and the luminance curve of the natural light is modeled and fitted to the current international human visual adaptation curve, thereby eliminating the need for enhanced lighting measures at the entrance. To verify the practicability and reliability of this scheme, the indexes of tunnel lighting like luminance, uniformity of luminance, evolution of luminance, and so on are evaluated by an experimental approach. The results show that the design index of the natural-light illumination scheme meets engineering requirements; compared with the conventional lamp lighting scheme, it basically eliminates the "black-hole effect" at the entrance and enhances tunnel traffic safety and comfort with the added advantages of saving energy and reducing emissions while being simple, useful, and cost-effective. 2014 Vol. 51 (3): 35-42 [Abstract] ( 2042 ) [HTML 1KB] [ PDF 0KB] ( 529 ) 43 Study of a Monitoring Information System for the Safety Risks of Urban Rail Transit Engineering YANG Shu-Cai Using modern information technology to monitor urban rail transit engineering in real time is one of the effective means of controlling safety risks of underground works. Based on the safety risk management system and control standards, a professional information management platform is developed that incorporates all sorts of data and information from various parties involved and uses modern techniques in terms of IOT, cloud computation, network communication, and GIS to monitor the safety of underground works through artificial, real time, on-site, and video monitoring means. This platform integrates hardware and software and covers major management elements like monitoring, supervising, evaluating, early warning, and emergency response. This is a comprehensive solution to engineering safety risks from the aspects of technique and management. 2014 Vol. 51 (3): 43-48 [Abstract] ( 2103 ) [HTML 1KB] [ PDF 0KB] ( 531 ) 49 Analysis and Control of Tunnel Structure Deformation Under Zero Overburden WU Hui-Ming-1, 2 , TANG , XUAN 3 The cut-and-cover method is normally used in the construction of works connecting surface roads and underground tunnels, which causes great environmental impacts to the ground. Ground Penetrating Shield Technology (GPST) is an effective way to solve this problem. Based on an experimental project, this paper demonstrates shield tunnel deformation control techniques, such as segment stabilization, synchronous grout control, and improvement of joint stiffness, by analyzing and calculating the influential factors of tunnel deformation. This extends the application of shield tunnelling and provides new ideas for tunnel planning and designing. 2014 Vol. 51 (3): 49-56 [Abstract] ( 2062 ) [HTML 1KB] [ PDF 0KB] ( 560 ) 57 Construction Adaptability of a TBM in the Zhongtianshan Tunnel YU , JIE Based on experience from the Qinling tunnel on the Xi'an-Ankang Railway and the application of a TBM in the Zhongtianshan tunnel at the Turpan-Korla section of the Southern Xingjiang Railway Line 2, the adaptability of TBMs is analyzed considering the topographical and geological conditions of the Zhongtianshan tunnel. According to the geological parameters and advance rates measured in the survey, design and construction stages, the effects of geological factors on TBM advance efficiency is discussed and an approach for adapting a TBM to geological conditions and improving the advance rate by specific measures is analyzed. The results show that the geological properties of surrounding rock greatly affect TBM advance efficiency and that an effective way to improve advance efficiency includes adopting high-quality wear-resistant cutting tools and increasing the gross thrust of the TBM. 2014 Vol. 51 (3): 57-60 [Abstract] ( 2025 ) [HTML 1KB] [ PDF 0KB] ( 538 ) 61 Research on Tunnel Drainage Control Based on Ecological Environment Protection LIU Jin-Gang The controlled drainage meets demands of both mitigating the water pressure on linings and maintaining the ecological balance in tunnel area. In a practical project, not only is it necessary to calculate the allowable drainage from the perspective of engineering safety, but also consider the habitation drinking and plants growth. In this paper, a steady flow model for tunnel drainage calculation is established based on Dupuit hypothesis in view of ecological environment protection. A calculation method for allowable water drainage is derived in light of the permitted dewatering level, and the control measures for tunnel drainage focusing on grouting are proposed. All this above provides a theoretical basis for ecological environment protection in tunnel area. 2014 Vol. 51 (3): 61-66 [Abstract] ( 1870 ) [HTML 1KB] [ PDF 0KB] ( 539 ) 67 Analysis of Karst Development Zones Based on Surface Settlement LIU Cheng-Yu-1, Liu-Zhao-Wei-2 Water inrush often occurs during tunnel construction in karst areas due to their complexity, and this frequently results in surface settlement. This paper proposes an analytical method for construction in a karst development zone in light of water inrush induced surface settlement, namely to analyze the features of the surface settlement with a settlement diagram, to determine the geological structures of the karst development zone, to study the zone's boundary with geological data related to the settlement area, and to analyze the supply relation between the water inrush and rivers according to the relationship between the settlement centre and the rivers. Additionally, using the data of surface settlement induced by water inrush at YDK24+098 of the Xiangshan tunnel on the Longyan-Xiamen railway, this paper analyzes the geological structures of the karst development zone, the longitudinal boundary of the karst, and the supply relation between the water inrush and the rivers, thereby verifying the feasibility of the above mentioned analytical method. 2014 Vol. 51 (3): 67-72 [Abstract] ( 1920 ) [HTML 1KB] [ PDF 0KB] ( 512 ) 73 A Study of the Mechanical Property of Schist Based on Microscopic Tests WANG Jia-Xing-1, 2 , SHI Yu-Chuan-1, DUAN Wei-Feng-3, JI , FENG 1, CHEN Guo-Qing-1 Generally, the macroscopic properties of a rock are reflected well in its micro-characteristics, so further research of microscopic properties is significant to the understanding of macroscopic properties and their practical applications in engineering. Using a lamellar casting test and a scanning electron microscope test, as well as the results of a point-loading test and a conventional mechanical test, the mineral composition and microstructure of surrounding rocks in the exploration adit of a hydropower station in southwest China was experimentally studied. The correlation between the micro-character and macro-mechanical properties of the rock was analyzed and the effects of the rock's micro-characteristics on the stability of the surrounding rock was stated from a microscopic view to establish the theoretical and technical basis for the design and construction of the tunnel support. 2014 Vol. 51 (3): 73-78 [Abstract] ( 1970 ) [HTML 1KB] [ PDF 0KB] ( 544 ) 79 A Study of the Nonlinear Creep Damage Model for Rocks WANG Jun-Bao-1, 2 , Liu-Xin-Rong-1, 2 , Shao-Zhu-Shan-1, Wang-Tie-Xing-1 To illustrate the entire process of rock creep, this paper presents an improved elastic component based on damage mechanics theory and Kachanov's creep damage law, which considers time-dependent damage and reflects the instantaneous deformation that occurs under loading and accelerated rock creep. Additionally, it sets forth a new two-component nonlinear creep damage model and deduces the creep equation by connecting the elastic component with a fractional order viscous component describing the attenuation and steady creep of rock in series. By comparing the creep test results with related literature, analysis shows that the proposed model can accurately reflect the three stages of the rock creep process and the fitting curve agrees well with the test curve, proving the rationality and applicability of the improved model. 2014 Vol. 51 (3): 79-104 [Abstract] ( 1853 ) [HTML 1KB] [ PDF 0KB] ( 535 ) 85 A Study on the Classification and Grading of Environmental Effects on Tunnel Structure Durability FENG Ji-Meng-1, Tian-Ming-Yang-2 The structural system and environment structure of a tunnel are distinctive from those of a structure on the ground, and the application of ground structure based durability design parameters to tunnel design has some flaws. By analyzing the structure, environment, and features of tunnel defects, in combination with the current code for environment classification, the structural environment of tunnels are classified into the three categories of general environment, erosive environment, and freezing and thawing environment, and each category is sub-classified as one of three grades according to the tunnel structure hazard levels. Additionally, five comprehensive grades are established based on various environmental combinations and safeguard measures are proposed regarding the durability of the tunnel structure system and the material. 2014 Vol. 51 (3): 85-90 [Abstract] ( 2211 ) [HTML 1KB] [ PDF 0KB] ( 521 ) 91 Durability Prediction Model for Tunnel Lining Concrete Under Sulfate Corrosion WANG Hai-Yan-1, Chou-Wen-Ge-2, Du-Li-Feng-1, Gong, LUN 2 A natural deterioration attenuation equation was derived by analyzing the mechanism of sulfate corrosion, and a model for predicting concrete durability under sulfate corrosion was established considering the definition of concrete durability set forth in specification, i.e. the concrete life is expired if the corrosion-resistance coefficient of the concrete strength is less than 75%. The functions of such influence coefficients as the sulfate mass concentration, water-cement ratio, mineral admixture species and dosages, as well as different curing methods, were set up by choosing some key reference points. Finally, an equation of concrete durability prediction under sulfate corrosion was obtained, and the durability of concrete prepared by various cementitious materials was predicted. The results show that the composite cementitious material has a positive effect in terms of sulfate corrosion resistance. This concrete durability prediction model, which takes various factors into consideration, is easy and practical. 2014 Vol. 51 (3): 91-94 [Abstract] ( 2124 ) [HTML 1KB] [ PDF 0KB] ( 505 ) 95 Experimental Study on the Diffusion Law of the Chloride Ion in a Shield Segment Under Coupled Erosion and Load LEI Ming-Feng-1, 2 , Peng-Li-Min-1, Xie-You-Jun-1, Tan-Li-Xin-2, Peng, BIN 2 Aimed at the environmental and mechanical characteristics of shield-driven tunnels, this paper establishes a 1D unilateral erosion test method for segments under the combined influence of chloride erosion and structural load and presents the results of tests conducted using a test device that was developed in a simulated environment. Furthermore, it discusses the influence of chloride ion concentration, erosion time, and load level on chloride ion diffusion and content distribution. The results show that the chloride ion content in the concrete cover increases gradually with the increase of chloride ion concentration and erosion time; the pore characteristics inside the concrete are changed by external loading, which directly affects the chloride ion penetration, manifesting in the fact that penetration is easier under tensile stress rather than compressive stress. 2014 Vol. 51 (3): 95-104 [Abstract] ( 1967 ) [HTML 1KB] [ PDF 0KB] ( 478 ) 105 Experimental Study Using a Shaking Table Model for a Tunnel Passing Through Faults (PartⅡ): Test Result Analysis WANG Zheng-Zheng-1, LI , BIN 2, GAO , BO 3, ZHU Chang-An-4, LIN Guo-Jin-4 Based on an experimental study using a shaking table model for a tunnel passing through faults, this paper analyzes the tunnel's dynamic response law, studies the lining cracking process and failure mode, and discusses the damping effect of a buffer layer. The results show that the seismic response of a tunnel passing through faults has the characteristics of asymmetry and a hanging wall effect, while the overall seismic performance is improved significantly; the lining is stressed uniformly both horizontally and vertically with the installation of the buffer layer. Especially for the invert, the tension stress state is greatly improved. The test results provide a reference for aseismatic tunnel design, post-disaster reconstruction, and the revision of corresponding codes in the future. 2014 Vol. 51 (3): 105-109 [Abstract] ( 2038 ) [HTML 1KB] [ PDF 0KB] ( 532 ) 110 Analysis of Local Damage Induced by Tunnelling in a Fractured Rock Mass Based on Noncontact Measurement Techniques WANG Shu-Hong, ZAN Shi-Ming, WANG Cun-Gen, NI , YONG The rational determination of an Excavation Damage Zone (EDZ) in fractured rock plays an important role in selecting an excavation method and support pattern. A quantitative analysis was carried out for an EDZ range and its mechanical properties using an optimized numerical model based on the fine measurement and characterization of the structural plane of the rock onsite. Using the excavation of a tunnel on the Jianchang-Xingcheng expressway as an example, information regarding the structural plane at the working face was collected by noncontact measurement, imported into the GeoSMA-3D system, and used to produce a 3D model approximating the actual situation. Based on this, the PFC method was adopted to determine the EDZ range, and comparative analyses of the surrounding rock stress curve, displacement curve, force chain distribution, and fracture distribution were carried out. The results show that the force chain concentration represents the degree of disturbance to the surrounding rock, while the fracture density represents the degree of damage, and the fracture connectivity implies the failure zone, by which the EDZ and the mechanical properties of the fractured rock mass can be accurately identified. The local damage during rock failure can be well simulated by the PFC method. 2014 Vol. 51 (3): 110-116 [Abstract] ( 2045 ) [HTML 1KB] [ PDF 0KB] ( 497 ) 117 Study of Boundary Conditions for the Numerical Simulation of Pressure Fluctuation Inside and Outside of a High-Speed Railway Tunnel WANG , RUI , Mei-Yuan-Gui, HAO , LEI , XU Jian-Lin When a train passes through a tunnel at a high speed, it will induce a pressure fluctuation inside and outside of the tunnel, including a pressure wave inside the tunnel and another at the tunnel entrance/exit. In a numerical simulation of these two aerodynamic phenomena, the selection of open boundary conditions and boundary conditions at the exit portal were critical. Based on a 3D compressible unsteady turbulence flow model, the sliding mesh technique of the CFD code was adopted to simulate the entire process of a high-speed train passing through a tunnel. The impacts on the calculation results for pressure waves inside the tunnel and at the tunnel entrance/exit induced by changing the open boundary conditions and the exit boundary conditions in two calculation domains were studied. The results show that the open boundary condition has a major impact on the wave at the tunnel entrance, as does the exit boundary condition on the tunnel pressure wave. Riemann boundary conditions are appropriate for the open boundary while studying the wave at the entrance/ exit, and the pressure boundary conditions are appropriate for the exit boundary while studying the tunnel pressure wave. 2014 Vol. 51 (3): 117-123 [Abstract] ( 1972 ) [HTML 1KB] [ PDF 0KB] ( 514 ) 124 Analysis and Calculation of Optimum TBM Disc Cutter Spacing FENG Huan-Huan, CHEN , KUI , ZHOU Jian-Jun, LI Feng-Yuan, WANG Zhu-Feng To further improve the rock-breaking performance of TBM cutters, it is particularly important to determine proper cutter spacing during the cutter design process. In this paper, based on a cutter spacing range derived from the rock crushing angle, an analysis of rock-breaking performance under double and triple cutters with different cutter spacings was carried out in accordance with the RFPA analytic system, and a calculation formula for optimum cutter spacing was deduced. Then, the self-developed comprehensive test platform was used to test rock-breaking performance during the sequential rolling of three cutters with different cutter spacings to verify the accuracy of this formula. The derived calculation formula for optimum cutter spacing was proven to be scientific by the test results, and the effective rock-breaking theory for cutters was further improved. 2014 Vol. 51 (3): 124-130 [Abstract] ( 2291 ) [HTML 1KB] [ PDF 0KB] ( 561 ) 131 Experimental Study of the Ultimate Bearing Capacity of a Shield Tunnel Reinforced by a Semi-Ring Steel Plate LIU , XIAN 1, Zhang-Hao-Li-1, Tang, MIN 1, Lu, LIANG 2, WANG Xiu-Zhi-3 A common method, semi-ring steel-plate reinforcement is mainly used for controlling large deformation of a tunnel lining, namely by providing post-reinforcement for the tunnel. Regarding the ultimate bearing test of a shield tunnel, this paper presents semi-ring steel-plate reinforcement technology, records the structure failure phenomenon that occurred during testing, gives the corresponding load-displacement curve, and analyzes key performance points. The results show that the given semi-ring steel-plate reinforcement can effectively improve the structural rigidity and ultimate bearing capacity of a tunnel, and that the failure of the bonding surface between the steel plate and the lining is the main cause of structural failure and a key factor in tunnel reinforcement. 2014 Vol. 51 (3): 131-137 [Abstract] ( 1924 ) [HTML 1KB] [ PDF 0KB] ( 523 ) 138 The Orthogonal Test Analysis of the Minimum Buried Depth of a Shallow Shield Tunnel JIAO Jian-Wei, Wang-Kong-Qian Serious accidents involving front collapse and water bursting are mostly attributed to the excessively thin overburden of shield tunnels. In this paper, the existing problems with the current calculation theory for the minimum buried depth of an underwater shield tunnel are analyzed and an improved calculation formula for minimum depth is given considering such factors as the anti-floating safety coefficient, soil shear strength, and grouting pressure behind the segment. Meanwhile, by using the orthogonal test analysis method without null columns, the range analysis and variance analysis of various factors that affect the determination of the tunnel buried depth, such as tunnel radius, segment thickness, grouting pressure, effective unit weight and effective internal friction angle of the overlaying soil, and soil viscosity, are carried out, and the significant influential factors for the minimum buried depth and its tendency to vary with various factors are derived. The study shows that segment thickness and effective internal friction angle have minimal influence on the variation of buried depth but grouting pressure greatly influences it. The order of influence of the factors related to the given formula is: grouting pressure, soil viscosity, effective unit weight of the soil, tunnel radius, effective internal friction angle of the soil, and segment thickness. 2014 Vol. 51 (3): 138-142 [Abstract] ( 2445 ) [HTML 1KB] [ PDF 0KB] ( 515 ) 143 The Influence of Parameters on the Stability of a Coal Roadway in Weakly Cemented Soft Rock and Stability Failure Features ZHAO Zeng-Hui-1, 2 , WANG Wei-Ming-3, YAN Ji-Xing-3 For a coal roadway in weakly cemented soft rock, it was critical to maintain stability of the mining zone, and in this case the failure features were closely related to the mechanical behaviors of the composite structure composed of rock, coal, and rock. A calculation model for a coal roadway featuring soft rock at both thetop and bottom was established. Orthogonal numerical tests were conducted with mixed levels, in which the strength, stiffness, thickness, and overburden of various rock and coal layers were selected as influential factors and displacements at the top, bottom, and two sides were used as an evaluation index. Five quantified influential levels of various factors were classified by defining the quantified index k and creating an evaluation standard by classifying the statistic F using different inspection levels, namely highly significant, significant, relatively significant, non-significant, and non-influential. The results show that: the stiffness of the coal seam has a significant impact on roadway deformation at a certain depth of overburden; various failures occur with the combination of different factors, such as tensile shear at the roof, floor, and coal seam, which can be used as a reference for analyzing the failure mechanism and potential roadway maintenance. 2014 Vol. 51 (3): 143-151 [Abstract] ( 1983 ) [HTML 1KB] [ PDF 0KB] ( 509 ) 152 Study of the Numerical Calculation of Ground Response Under Metro Traffic Loading in a Loess Area WANG Xin, Han-Xuan, ZHOU Hong-Lei Based on the Xi'an Metro Line 2, metro traffic loading is simulated by establishing an analytical model of a subgrade train-track system and a material mechanical model of a loess soil mass under the effects of long-term cyclic loading is derived and introduced according to the results of a dynamic triaxial test. Reasonable calculating parameters for the studied object are set, especially a series of numerical calculating conditions, such as artificial nonlinear viscoelasticity boundary conditions, to establish the numerical analytical model considering the dynamic interaction between a tunnel and surrounding soil and to study the regularity of the ground vibration response under metro traffic loading in a loess area. In addition, the variation of the ground vibration response under different speeds and various loads is analyzed and compared with respect to one-way and two-way metro traffic modes. 2014 Vol. 51 (3): 152-160 [Abstract] ( 1917 ) [HTML 1KB] [ PDF 0KB] ( 456 ) 161 Analysis and Evaluation of Deformation Prediction for Soil Tunnels Based on the Grey Theory with Upper and Lower Bounds TIAN Gang, Bai-Ming-Zhou, WANG Cheng-Liang, DU Yan-Qing, XU Zhao-Yi In tunnel deformation prediction, the grey model can be used to only predict the general trend of tunnel deformation, not to reflect the volatility caused by prediction errors. Therefore, early warning for tunnel deformation is difficult. In order to address the shortcomings of grey theory regarding the prediction of soil tunnel deformation, a grey theory with upper and lower bounds was put forward, and the upper and lower bounds in grey prediction were defined by processing the prediction errors in the grey model. With a given prediction zone, this method improved the grey prediction form (point by point) in time-series, providing warning time for tunnel deformation. Meanwhile, according to the intersection forms of the deformation control lines, grey limit curves, and grey midline, the safety levels regarding soil tunnel deformation were classified so that the safety of soil tunnels can be estimated more reasonably. 2014 Vol. 51 (3): 161-167 [Abstract] ( 1911 ) [HTML 1KB] [ PDF 0KB] ( 479 ) 168 Analysis of the Influence of Shield Tunnelling in Cumulosol Strata on Adjacent Bridges NI An-Bin Taking the construction of Kunming metro line 3 as an example, this paper simulates the influence of shield tunnelling in cumulosol strata on adjacent bridges with FEM software, analyzes the law of ground settlement and bridge pile foundation displacement, and compares the simulated data with the measured data. The results showed that: shield tunnelling in cumulosol strata may cause great ground settlement and pile foundation displacement, while a certain range of reinforcement can effectively reduce them; the simulated ground settlement and bridge displacement after ground reinforcement are close to the site measured results, validating its accuracy and feasibility. 2014 Vol. 51 (3): 168-173 [Abstract] ( 1967 ) [HTML 1KB] [ PDF 0KB] ( 470 ) 174 Application of Lengthened Rock Bolts for Large Deformation Control in a Soft Rock Tunnel SUN Yang, Zuo-Chang-Qun, Liu-Miao, Tang-Xia, CHEN Jian-Ping For controlling large deformation of soft rock tunnels, a support scheme with lengthened rock blots is presented after an analysis of large deformation causes was performed using the Siping tunnel on the Gucheng-Zhuxi highway as an example. In the past, the length of systematic anchor bolts was determined empirically and lacked reasonability. So an in-situ wave velocity test and theoretical calculations were used to determine the proper length of rock bolts, and finally it was determined that the rock bolts should be 5m in length based upon the effects of safety and economy. Based on the in-situ monitoring and measurement, along with a site test, a comparison test was adopted for the new support option featuring lengthened rock bolts and the original heavy-support option. The results show that the lengthened rock bolts can control deformation more effectively and take advantage of rock masses with self-stability and the ability for self-support in light of rock deformation, force, and the force pattern of the support structure. 2014 Vol. 51 (3): 174-180 [Abstract] ( 1935 ) [HTML 1KB] [ PDF 0KB] ( 522 ) 181 Key Techniques of the Arch-Cover Method for Bored Metro Stations Lv Bo Considering the great strength and stability of medium weathered slate, the innovative arch-cover method was successfully adopted for the first time in construction of the large-span shallow-buried bored metro stations of the Dalian metro project. Based on the design and construction of the Zhongshan Square station, the core concept and advantages and disadvantages of the arch-cover method are compared with the PBA method in this paper. After completion of the primary support at the arch, the three different construction sequences of top-down, semi-top-down and semi-bottom-up, and bottom-up were analyzed and compared in detail from the aspects of safety, quality, progress, and additional measures. Results show that the top-down method was undoubtedly the most reliable when experience and relevant data are lacking. Countermeasures against construction problems, such as a large arch spring, arch support, medial plate, drill-blasting, and steel pipe column protection, as well as surrounding rock support for the high side wall, are put forward. Finally, the optimization suggestion of the arch-cover method is presented. 2014 Vol. 51 (3): 181-187 [Abstract] ( 2302 ) [HTML 1KB] [ PDF 0KB] ( 463 ) 188 Technology for the Treatment of Local Water Seepage of a Grout Curtain Adopted in a Deep Water-Rich Foundation Pit LI Yi-Tang  Utilizing project experience, this paper analyzes the cause of local seepage of a "bored pile+twin-tube jet grouting pile" grout curtain under a high-pressure, water-rich sand formation in a floodplain area of the Songhuajiang River. Such measures as vertical ground grouting, oblique grouting consolidation between the piles, exploratory excavation, enclosure of steel plates, intensive mesh+shotcrete support, and rapid subsealing were carried out to overcome the difficulty related to local seepage of the grout curtain during excavation of the deep foundation pit, ensuring successful construction. 2014 Vol. 51 (3): 188-192 [Abstract] ( 2133 ) [HTML 1KB] [ PDF 0KB] ( 453 ) 193 Influence of Launching Shaft Construction on Surrounding Pipeline Deformation and a Control Technique GAO Bing-Li, REN Jian-Xi To avoid impacts from metro construction, some pipelines are necessarily removed. In irremovable cases, however, rational measures shall be taken to ensure minimal impact on surrounding pipelines from launching shaft construction. Using the construction of the Xi'an Metro Line 3 as an example, this paper establishes a FLAC calculation model for construction of the launching shaft, presents a pipeline monitoring scheme, analyzes the influence of launching shaft construction on supply and drainage pipeline deformation at the Tonghuamen-Hujiamiao section, and proposes reasonable protective measures. The results show that launching shaft construction has different levels of influence on the surroundings, namely, as the distance from the launching shaft increases, the influence decreases gradually. According to the research, the calculation results are basically in agreement with the monitoring results and the given scheme is effective at reducing pipeline deformation induced by the launching shaft construction. 2014 Vol. 51 (3): 193-199 [Abstract] ( 2023 ) [HTML 1KB] [ PDF 0KB] ( 502 ) 200 The Mechanism and Application of Dry Dust Removal Technology in Long Tunnel Construction ZHAO Yu-Bao, CHEN Shou-Gen, TAN Xin-Rong The large amount of dust that emerges during long tunnel construction is harmful to the health of workers. To improve dust-removal technology during tunnel construction, the mechanism of dry dust-removal technology is analyzed and the technology and performance of a dry dust-removing machine are discussed in this paper based on research of state-of-the-art dust-removal technologies at home and abroad. During construction, the dry dust-removal machine is placed 30m behind the tunnel face where the dust concentration is higher. Dust-removal is mainly focused on the construction sequences of blasting and shotcreting, and its effects are significant. This study shows that the installed ventilation system can exhaust noxious CO gases out of the tunnel and that the dust-removal machine can decrease the concentration of dust from 75mg/m3 to 3mg/m3 after two minutes of operation. The problem of dust concentration exceeding acceptable standards during long tunnel construction can be successfully solved by using a dry dust-removal machine in combination with a jet flow ventilator. 2014 Vol. 51 (3): 200-205 [Abstract] ( 2121 ) [HTML 1KB] [ PDF 0KB] ( 518 ) 206 Application of the Distributed Fiber Optic Temperature Sensor System in the Railway Tunnel DU Wen-Bin Based on the characteristics of distributed fiber optic temperature sensor system and temperature monitoring in the Yuanbaoshan tunnel on the Chengdu-Chongqing passenger dedicated line, this paper analyzes its equipment selection and installation, and verifies its monitoring effects by a fire test. The results show that this system can achieve continuous and dynamic temperature monitoring, effective early warning and precise positioning for fire source, providing scientific basis for the disaster rescue and evaluation. 2014 Vol. 51 (3): 206-210 [Abstract] ( 2075 ) [HTML 1KB] [ PDF 0KB] ( 485 )

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