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Quick Search     Advanced Search MODERN TUNNELLING TECHNOLOGY   2014 Vol.51 Issue.2 Published 2014-04-25 Article 1 On Calculation of Tunnel Lining Structure WANG Jian-Yu The provision for the calculation of the pressure of unsupported surrounding rock based on the weight of collapsed rock in Code for Design of Tunnel is not applicable to the NATM engineering practice. If the knowledge of lining load is constrained by the statistical formula of landslides, it's hard to conceive the design of tunnel by using probabilistic limit state method under the reliability theory. Hence, it is suggested more engineering analogy cases be added, relevant structural calculations be removed and numerical method be widely used in the stability analysis of surrounding rock considering the Code for Tunnel Design, providing a qualitative guidance for the tunnel design. 2014 Vol. 51 (2): 1-4 [Abstract] ( 2323 ) [HTML 1KB] [ PDF 0KB] ( 547 ) 5 Analysis of Key Problems in the Structural Performance Evaluation for TBM Cutter Heads LIU Jian-Qin-1, LIU Meng-Meng-2, GUO , WEI 2, WANG Lei-1 As a critical component of the TBM, the structural performance of the cutter head will affect its construction efficiency, cost and safety. Therefore, a comprehensive assessment of the structural performance of cutter heads has an important guiding significance to engineering practices. This paper first summarizes the international research of cutter heads from three aspects, i.e. the rock breaking mechanism, structure design and driving performance, and then concludes with the research results and existing limitations. Based on the research, the key points of evaluation of the structural performance of TBM cutter heads is put forward. The research suggests considering the structure parameters of cutter heads in order to further improve the cutter rock breaking mechanism, structural design and prediction models of driving performance. 2014 Vol. 51 (2): 5-10 [Abstract] ( 2259 ) [HTML 1KB] [ PDF 0KB] ( 527 ) 11 Real-Time Monitoring and Early Alarms for Collapse Prevention in a Shallow Loess Tunnel with a Large Section MA Shi-Wei-1, HAN Xue-Quan-2, LIAO , KAI 1 In order to reduce collapse damage to tunnels, based on the example of engineering in a shallow loess tunnel with a large section, the method of real-time monitoring of and early alarms for tunnel collapse is put forward. The principles of establishing early-alarm benchmark values and standards for early-alarm grading are presented, and an early-alarm system for tunnel collapse prevention (both hardware and software) is developed and tested on site. Testing results show that the hardware and software are reliable and adaptable to complex tunnel construction environments, the acquisition and transmission of data from the testing instruments performs normally, and the software system data vary with the real-time monitoring data, resulting in a grading of alarms. 2014 Vol. 51 (2): 11-15 [Abstract] ( 2099 ) [HTML 1KB] [ PDF 0KB] ( 526 ) 16 Application Study of the Construction Safety Risk Control Technology Standard for Urban Rail Transit Engineering YANG Shu-Cai Aiming at safety risk management and control in urban rail transit construction, a standard system of safety risk management and control technology standards for the civil construction of underground works is presented with a focus on key points and core technology. Firstly, the risk identification and grading standards are set up regarding the underground engineering and surroundings. Secondly, design standards for safety risk control are proposed on the basis of geotechnical surveys and environmental investigations. Thirdly, a safety risk early-warning system combining monitoring, patrolling and an integrated warning is presented along with its reference standards. Engineering practice shows that this standard system is applicable, feasible and scientific. 2014 Vol. 51 (2): 16-22 [Abstract] ( 2281 ) [HTML 1KB] [ PDF 0KB] ( 575 ) 23 Establishment and Application of a Dynamic Monitoring System for the Groundwater Environment in a Karst Tunnel Area LIU , JIAN 1, Liu, DAN 1, Lai, MING 2 Ecological environments are affected by continuous drainage from tunnels, which may cause disputes in some cases. A dynamic monitoring system for the groundwater environment in a karst tunnel area is established, and the monitored scope, layout of points, index, monitoring time interval and frequency are described in detail. Using the Tongluoshan tunnel on the Dianjiang-Linshui expressway as an example, the following conclusions were made based on the feedback information related to water quality and volume during the construction: 1) natural water is mainly replenished by atmospheric precipitation; 2) water inflow is composed of karst water and fissure groundwater, and 3) the groundwater environment at the middle of the tunnel and 1km away from the tunnel axis is affected by tunnel drainage to some extent. 2014 Vol. 51 (2): 23-29 [Abstract] ( 2223 ) [HTML 1KB] [ PDF 0KB] ( 535 ) 30 Development and Application of Fully Automated Calculation Software SDC for Tunnel Structures TIAN Zhi-Yu-1, LIN Guo-Jin-1, DING , YAO 1, ZHENG Jin-Long-1, LIANG Shun-Yun-2 The fully automated calculation software SDC for tunnel structures is characterized by convenience, high efficiency and practicability，and is widely used in many fields of tunnel engineering. Based on several engineering calculation cases, this paper demonstrates that the internal force and safety coefficient can be calculated accurately by numerical analysis for tunnel structures with explicit loads, achieving optimization and safety while being economic and rational. 2014 Vol. 51 (2): 30-35 [Abstract] ( 2194 ) [HTML 1KB] [ PDF 0KB] ( 512 ) 36 Research on Properties of a Shape Memory Alloy (SMA) Concrete "Two-Way Beam" Applied in Underground Engineering ')" href="#"> YIN , KE 1, 2 , YU Zhi-Gang-1, 3 Based on the two-way shape memory effect of Shape Memory Alloy (SMA) , an SMA concrete "two-way beam" is put forward as a new kind of smart structure. Based on mechanical knowledge, the mechanical properties of a reinforced concrete beam and the SMA "two-way beam" were compared under three conditions (i.e., the temperature of the tensile part being greater than, lesser than and equal to the temperature of the compressive part). The recovery effect of the SMA beam was analyzed and calculated under a high excitation temperature. Additionally, problems to be solved before the application and promotion of the SMA concrete "two-way beam" are presented, along with suggested future research in the field. The results show that it is not an effective way to increase sectional dimensions to improve the stress state of a beam with temperature differences between the upper and lower surfaces; the stress mechanism analysis is in agreement with the computational analysis; the SMA has an actuating effect on "two-way beam" deformation during the phase transformation process and actively controls and adjusts the deflection value of the beam while decreasing the bending moment and axial force of the beam induced by temperature differences. This "two-way structure" can improve crack resistance and is suitable for underground engineering. 2014 Vol. 51 (2): 36-42 [Abstract] ( 2182 ) [HTML 1KB] [ PDF 0KB] ( 539 ) 43 Experimental Study of the Fire-Resistance of Structural Elements of Immersed Tunnels JIANG Shu-Ping-1, Zhang-恩Qing-2, Guo, JUN 1, Liu, SHUAI 1, Zhang-Zhu-Yong-3 Based on the National Science and Technology Support Plan, a self-designed high temperature ablation test platform was established, and high temperature ablation tests using different fire-resistant technologies (fireproof board and fireproof coating) were conducted considering the characteristics of immersed tunnels by using a 1∶1 local structural element made from C50 concrete. An appropriate fire-resistant scheme for the concrete structure that can withstand fire for 2 hours and meets the requirements of the HC or RABT heating curve is put forward after experimental analysis. In addition, some practical suggestions are presented. 2014 Vol. 51 (2): 43-49 [Abstract] ( 2090 ) [HTML 1KB] [ PDF 0KB] ( 505 ) 50 Experimental Study Using a Shaking Table Model for a Tunnel Passing Through Faults ( Part I): Test Scheme Design WANG Zheng-Zheng-1, GAO , BO 2, LI , BIN 3, ZHU Chang-An-4 Having a section that passes through a fault is one vulnerability regarding the seismic resistance of a tunnel. Based on the Ya'an-Lugu expressway tunnel in an area of southwest China characterized by high seismic intensity, an experimental study using a shaking table model for tunnels passing through faults was conducted, which determined the similarity relation of the model systems according to test conditions and the shaking table performance. Then, similar materials were finalized through indoor ratio tests, and the model casing was designed according to testing characteristics. The "model casing effects" were analyzed and handled, and a reasonable layout of sensors was carried out as per numerical calculation results. Finally, the test conditions were designed according to the test intentions. 2014 Vol. 51 (2): 50-55 [Abstract] ( 2167 ) [HTML 1KB] [ PDF 0KB] ( 545 ) 56 Characteristics of the Earthquake Dynamic Response and Corresponding Reinforcement of the Tunnel Face LI , Bin-1, 2 Based on the Shimian Tunnel on the Ya'an-Lugu highway, this paper analyzes the effects of the earthquake dynamic response on the tunnel face and corresponding reinforcement measures. First, it describes the main types of earthquake hazards in tunnels and the mechanical equilibrium mechanism at the working face, and performs an earthquake dynamic response analysis using FLAC3D finite difference software aiming at analyzing the effects of earthquake on stability of working faces in different strata through comparing the working face stability condition under static and dynamic action. Then it summarizes the law of extrusion deformation and confinement pressure varying with the time-history of an earthquake. Using the average plastic shear strain, extrusion deformation and confinement pressure at the working face, it evaluates the reinforcement effects on the working face. Finally, it derives the following conclusions: the tunnel working face is more likely to be destroyed by an earthquake than the tunnel lining; there are different degrees of influence of the earthquake dynamic response on the tunnel working face in various strata, that is to say, the impact is less in a rocky stratum and greater in a soil stratum; and anchor reinforcement greatly improves the aseismic performance of the tunnel working face. 2014 Vol. 51 (2): 56-62 [Abstract] ( 2315 ) [HTML 1KB] [ PDF 0KB] ( 550 ) 63 The Calculation of Soil Settlement Induced by Construction of Twin Parallel Shield Tunnels with a Small-Interval WU Hua-Jun-1, Wei, GANG 2 This paper presents that the curve of soil settlement induced by small-interval double-bore parallel shield tunnel construction conforms with the normal distribution, and summarizes the calculation method for surface settlement. Aiming at the deficiencies of various calculation methods, the modified 2D Peck formula is established to calculate the deep soil settlement while considering the asymmetry of the settlement curve. Based on the research of calculation parameters, the measured results show that iTotal / iAdvancing tunnel (i: width coefficient of the settlement trough) decreases linearly with the increase of h/D, thus giving the formula for iTotal and ηTotal (η : Soil loss rate). Additionally, this paper firstly proposes the coefficient C of relative horizontal distance between two tunnel axes (C＜0.6; C=L/(h+R)), to which the shape of the total ground settlement curve is related. According to the case study, the predicted values agree with the measured ones and the calculation is relatively simple. 2014 Vol. 51 (2): 63-69 [Abstract] ( 2695 ) [HTML 1KB] [ PDF 0KB] ( 534 ) 70 Analysis of the Plastic Zone of Surrounding Rock Under Seepage and a Non-Axisymmetric Load GAO Zhao-Ning-1, MENG Xiang-Rui-1, Wang-Guang-Di-2 Taking the seepage body force into consideration, this paper derives the rock stress distribution and plastic zone expressions under the seepage field and analyzes the relationships of the plastic zone range to the porewater pressure, lateral pressure coefficient and the ratio K between the rock mass strength and initial geostress. The results show that the seepage field has an effect on the plastic zone range, but not on its shape. With variation of lateral pressure coefficients and K values, the effect of seepage on the plastic zone range presents anisotropy along different directions. Furthermore, the anisotropic degree decreases gradually with the increase of the lateral pressure coefficient and K value. The lateral pressure coefficient and the K value not only affect the plastic zone range, but also its shape. When K＜1, the effect from the lateral pressure coefficient plays an important role. Whereas, rock mass strength plays the leading role when K＞1, namely, the plastic zone range decreases gradually with the increase of the rock's compressive strength. Additionally, the plastic zone is more likely to appear at the two sides of the tunnel with a decrease of the lateral pressure coefficient. 2014 Vol. 51 (2): 70-75 [Abstract] ( 2166 ) [HTML 1KB] [ PDF 0KB] ( 528 ) 76 Laws of Surface Subsidence Caused by the Excavation of a Bored Subway Tunnel in a Water-Rich Mixed Ground in Shenzhen LI , TAO 1, HAN Xue-Feng-2, HUANG , HUA 1, LIU , WEI 1 In urban metro design, it is necessary to understand the laws of surface subsidence caused by subway tunnel construction. Using the Shenzhen Metro Line 5 as an example, over 22,000 surface subsidence monitoring data were properly selected from 19 bored running tunnels for a statistical analysis, and the laws of the longitudinal and transverse distribution as well as the variations of the surface subsidences along the tunnel in each bored running tunnel were obtained. The results show that the distribution law of the maximum accumulative surface subsidence in each running tunnel is uneven (with an average of 82.3mm, a maximum of 688.7mm and a minimum of only 7.8mm) and the range of transverse surface subsidence in the tunnel is different from one another (with a maximum of 140.47m, minimum of 28.63m and average of 46.78m). Because of the large differences between the measured data and the maximum surface settlement control standards allowed by existing specifications, adoption of the new three-level control baseline that is suitable for controlling the surface subsidence caused by the bored excavation of subway tunnels in water-rich mixed ground is suggested for reasons of economy and rationality. 2014 Vol. 51 (2): 76-82 [Abstract] ( 2406 ) [HTML 1KB] [ PDF 0KB] ( 524 ) 83 Prediction of Surrounding Rock Deformation of the Daxiangling Tunnel in Fault Zones Using the GA-BP Nerve Network Technique ZHANG Zhi-Qiang, LI Hua-Yun, HAN , CHENG , SHENG , YUE , SUN , FEI Predicting surrounding rock deformation in fault zones has been much debated in observation-based tunnel construction and management, but so far a scientific and rational method for this sort of prediction is lacking. For NATM tunnelling, surrounding rock deformation is often used as an important indicator to judge the stability of a tunnel and the economic rationality of the supporting structure. As surrounding rock deformation is a kind of series varying with time, a prediction model is established to trace and predict deformation in real time. Considering the large deformation rate of the surrounding rock around the Daxiangling Tunnel on the Ya'an-Xichang expressway, a BP artificial neural network based genetic algorithm is introduced, improving prediction accuracy by modifying the basic genetic algorithm. Using GA-BP neural network techniques, a comprehensive model to predict rock deformation in a fractured fault zone is established and applied to the Daxiangling tunnel, and the predicted results are verified to be accurate and reliable. 2014 Vol. 51 (2): 83-89 [Abstract] ( 2457 ) [HTML 1KB] [ PDF 0KB] ( 530 ) 90 A Study of the Reliability Design of Tunnel Lining Structures Based on the Load-Structure Model NIU Ze-Lin-1, 2 , Zhang-Song-Tao-2, Wu-Huan-Tong-2, Dai-Ya-Lei-2, Han-Wei-Hui-2 Using the Qindong railway tunnel in the loess area as an example and based on the "load-structure" model, the Monte Carlo finite element analysis and the statistic knowledge, as well as mathematical statistical characteristics of parameters related to surrounding rocks, this paper studies and analyzes the reliability of tunnel lining structures by carrying out structural calculations. A calculation model for reliability design of the tunnel lining structure is established and the statistic characteristics and distribution patterns of the axial forces of a large-section loess tunnel structure are obtained. Additionally, the calculation means available for the reliability design of tunnel lining structures are proposed, providing a guide for the application of structural reliability theory to the reliability design of tunnel lining structures. 2014 Vol. 51 (2): 90-94 [Abstract] ( 2291 ) [HTML 1KB] [ PDF 0KB] ( 535 ) 95 An Analytical Solution for the Internal Force of the Lining Segment in Composite Support System for Tunnels Driven with Combined D&B and Shield Construction Method ZHANG Chang-Guang-1, Zhao-Jun-Hai-1, Zhang-Qing-He-2 Aiming at the composite support system in combined D&B and shield construction method , a basic hypothesis for model analysis is proposed. The initial ground stress is divided into hydrostatic stress component and tension-compression deviatoric stress component. The supporting time and spatial effect of the excavation face are reflected by stress relief coefficients of the surrounding rocks. Using the elastic mechanics theory, the elastic analytical solutions for the bending moment and axial force of the lining segment under unequal ground stresses in two directions are derived. Based on the engineering practice used in a running tunnel of the Shenzhen Metro, the influential characteristics of various parameters such as the rock stress-relief coefficient, lateral pressure coefficient, thickness and elastic modulus of the back filling layer are obtained. It provides theoretical support for the promotion of this new construction method and for the design of lining segmentsin composite support system. 2014 Vol. 51 (2): 95-100 [Abstract] ( 2130 ) [HTML 1KB] [ PDF 0KB] ( 504 ) 101 Key Points of the Design for Underwater Tunnels Using the Mined Method ZHANG Xian-Feng Compared with conventional tunnels, there are some varying features regarding the design of underwater tunnels, and the underwater tunnel can be constructed with different methods. The key points to consider in the design are demonstrated in terms of geological conditions, link conditions, environmental conditions and construction costs. As for the mined underwater tunnel, it is thought the depth of the rock cover, the type of water-proofing and drainage will directly affect tunnel safety and economy. Based on demonstration and analysis, the method and principles used to determine tunnel overburden, the type of water-proofing and drainage are presented. For the determination of water pressure, which has been a tough problem in tunnel design, corresponding calculations are given considering different methods of water-proofing and drainage. In addition, construction methods to ensure tunnel durability and safety are presented by using a specific tunnel as an example. 2014 Vol. 51 (2): 101-107 [Abstract] ( 2483 ) [HTML 1KB] [ PDF 0KB] ( 527 ) 108 Application of the Advance Support of High-Pressure Horizontal Jet Grouting Piles in Tunnel Engineering XIAO Guang-Zhi, You, Xu This paper introduces the mechanism, features, and construction technologies of high-pressure horizontal jet grouting piles as well as their general application and some example projects. It also presents the application conditions and some relevant suggestions regarding the technological development of high-pressure horizontal jet grouting piles as advance support in tunnels and underground engineering. 2014 Vol. 51 (2): 108-114 [Abstract] ( 2440 ) [HTML 1KB] [ PDF 0KB] ( 545 ) 115 Tunnel Construction Procedures in a Tertiary Water-Rich Fine Sandstone Stratum with Weak Muddy Cementation SI Jian-Jun During the early stages, the construction of the Taoshuping tunnel on the Lanzhou-Chongqing railway in a tertiary water-rich fine-sand stratum is very difficult and highly risky because of the softening of surrounding rock that encounters water. In this paper, construction methods and relevant auxiliary measures for this early stage are verified and categorized by establishing procedures on the premise of emphasizing dewatering, increasing pipe density, improving support and matching grouting. Aiming at the tertiary water-rich fine sandstone stratum with weak muddy cementation, this paper focuses on the verification and analysis of procedures like in-tunnel dewatering, advance support, support structure and radial grouting, providing a practical basis for the design rationality of support parameters for the main tunnel. 2014 Vol. 51 (2): 115-121 [Abstract] ( 2682 ) [HTML 1KB] [ PDF 0KB] ( 527 ) 122 Construction Techniques for Mutually Connected Clustered Excavations with Complex Ventilation Channels and Rooms ZHU Chao-Zuo Based on the No.2 ventilation shaft of the Jiaozhou Bay Subsea tunnel, the characteristics, scope and the extent of the effects of construction at the intersections of clustered excavations and key sections adjacent to the tunnel are obtained by means of the analysis and numerical simulation of various cases using FLAC3D. Additionally, the rational construction methods and key reinforcement scope are determined. By adopting the measures of smooth blasting and support reinforcement, the safety and quality of the construction of clustered excavations are guaranteed. 2014 Vol. 51 (2): 122-126 [Abstract] ( 2675 ) [HTML 1KB] [ PDF 0KB] ( 511 ) 127 The Application of CREC-TBM to the Chengdu Metro Construction in a Sandy Cobble Stratum CAO Zhi Aiming at the problems encountered in the Chengdu metro construction driven by a shield machine in a sandy cobble stratum (such as smaller shield torque; serious wear of the cutter, cutterhead and screw conveyor: poor muck conditioning; and obvious post-construction settlement), some countermeasures are carried out to improve the design of the CREC-TBM. These measures include a reasonable main drive torque and precise penetration in order to avoid the risks of an automatic reduction of speed and effectively prevent the cutterhead from getting stuck. Attributed to the good design and arrangement of the cutterhead and cutter, muck accumulation and muck cakes are reduced, thereby benefiting muck mixing. With sound muck conditioning, cutter wear and replacement frequency are reduced and the driving distance is extended accordingly. The results show that the CREC-TBM is suited to construction in the water-rich sandy cobble stratum, with post-construction settlement meeting the relative specifications. 2014 Vol. 51 (2): 127-132 [Abstract] ( 2563 ) [HTML 1KB] [ PDF 0KB] ( 552 ) 133 Technical Study of a Bored Tunnel Passing Under an Existing Subway Station HUANG Zuo-Qiong Three tunnels of the Guangzhou Metro Line 6 will pass under the Guangzhou Metro Line 2 and the running tunnel at the Haizhu Square Station, which makes construction extremely difficult due to the small vertical distance between these structures. In this paper, the overall construction principle and scheme is presented in light of the spatial relationship of the bored tunnels of the Zhuhai Square Station and the existing Guangzhou Metro Line 2 and the engineering hydrogeological conditions. The detailed construction and monitoring techniques for the platform tunnel of the left bore and the running tunnels of both the left and right bores passing under the existing Line 2 are described. Ultimately, the bored tunnels passed through the existing Guangzhou Metro Line 2 safely and smoothly, ensuring the safety of surrounding buildings and normal operation of the Guangzhou Metro Line 2. 2014 Vol. 51 (2): 133-139 [Abstract] ( 2140 ) [HTML 1KB] [ PDF 0KB] ( 494 ) 140 Discussion and Analysis of the Rock Breaking Techniques for the Tunnel Shield-Launching End LIAN Chang-Jiang, Li-Jian-Ping Nowadays the shield construction method is widely applied in the urban metro projects. The success of shield tunnelling is directly related to the stratum conditions that the tunnel passes through, especially at the shield-launching end. It is unfavorable for shield tunnelling if the upper stratum is soft and the lower stratum is hard. Using a slurry shield launching in these conditions for the Guangzhou Metro Line 9 as an example, this paper studies the method of building multiple shafts at the ground surface, through which the hard rock can be removed safely and rapidly at the shield-launching end while avoiding ground strengthening treatments. 2014 Vol. 51 (2): 140-146 [Abstract] ( 2221 ) [HTML 1KB] [ PDF 0KB] ( 538 ) 147 Safe Shield Tunnelling Under Buildings LIU Xue-Yan-1, 2 , Yuan-Da-Jun-1, 2 , Qiao-Guo-Gang-3, Wang, FEI 1, 2 , Chen-Hai-Feng-4 The Suzhou Metro Line 2 passes beneath 480 buildings in the old town of Suzhou. Since most of the buildings have no foundations or have simple strip foundations, they are inclined to crack or collapse due to deformation. Line 2 is constructed in silt and silty sand with a high water table and high water permeability, and potential drift sand or soil hardening can easily result in work-face failure because of soil disturbances caused by shield tunnelling. Although shield tunnelling technology has been developed along with the improvement of shield performance, it is still a new challenge to successfully tunnelling adjacent to a large number of buildings. Based on the driving speed, grouting material and grouting trials on-site, the scope of influence, control standards for surface settlement, driving speed, grout components and mix proportion, grouting volume and grouting time during shield tunnelling are given, which provides technical support for the safe shield tunnelling of the Suzhou Metro Line 2. 2014 Vol. 51 (2): 147-151 [Abstract] ( 2348 ) [HTML 1KB] [ PDF 0KB] ( 473 ) 152 Deformation Control for a Large Section Tunnel in Water-Rich Mylonite with Grade Ⅵ SUN Ming-Biao The exit section (510 m) of the Xiuning tunnel on the rebuilt Chengdu-Kunming railway, passing under the Longtan reservoir, is located in the Luoci-Yimen fault zone. The stratum is composed of rare water-rich mylonite with a classification of grade VI. After excavation, mylonite in the form of plastic flow can easily cause mud gushing and collapse, resulting in large deformation of the primary lining. To pass through this stratum safely and quickly, the deformation of the surrounding rock has to be controlled. Based on a water stability test of mylonite shear strength, this paper presents a support method for this section, namely, full-face pre-grouting with pipe-roof support. Using numerical simulation and deformation monitoring of the surrounding rock and lining structure, it was proven that full-face pre-grouting can effectively achieve water blocking, water squeezing, drainage consolidation and rock strength improvement; pipe-roof pre-support and three-bench seven-step excavation can effectively control rock deformation, ensuring construction safety. 2014 Vol. 51 (2): 152-156 [Abstract] ( 2100 ) [HTML 1KB] [ PDF 0KB] ( 494 ) 157 Treatment Techniques for and Monitoring Result Analysis of the Baishan Tunnel Collapse RAO Jun-Ying-1, FU He-Lin-1, LI , MING 2, LIU Yun-Si-1, YIN , QUAN 1, ZHANG Hai-Ming-3 According to the development and mechanism of a collapse in the left bore of the Baishan tunnel, a comprehensive treatment scheme, which covers surface drainage, rock mass grouting, lining reinforcement and base settlement prevention, is put forward. After the implementation of this scheme, an analysis of the rules of surface subsidence, crown settlement, horizontal convergence at the haunch and side wall is performed, and the development tendencies of the water pressure behind the primary support, contact stress between the primary support and surrounding rock, axial force of the anchor, stress on the profile steel arch and stress on the secondary concrete lining are discussed. The results show that the secondary lining at the arch walls improves the condition of contact stress between the primary support and surrounding rock in a weak surrounding rock section, decreases the surface subsidence and peripheral displacement, effectively shares part of the load on the anchor and steel arch, and improves the force state of the secondary lining of the invert. With good implementation of this scheme, safe construction of the remaining sections is guaranteed. 2014 Vol. 51 (2): 157-166 [Abstract] ( 2114 ) [HTML 1KB] [ PDF 0KB] ( 522 ) 167 A Study of the Technology for Railway Gas Tunnel Construction ZHAO , YU In this paper, the key points for construction management of gas tunnels are defined through the analysis of gas characteristics. Considering the characteristics of gas tunnel construction, the achieved results and implementation of such construction techniques and measures as advance probing, forced ventilation, frequent inspection, short advance, explosion-proof equipment and construction management strengthening are presented by using the Tiantaisi gas tunnel as an example. 2014 Vol. 51 (2): 167-171 [Abstract] ( 2053 ) [HTML 1KB] [ PDF 0KB] ( 509 ) 172 Analysis of the Treatment of Collapses in the Qingshui Tunnel on the Lanzhou-Chongqing Railway QI , SU 1, WANG Li-Ying-2, CUI Xiao-Peng-2, ZHANG , YE 1 Several collapses occurred during the construction of the Qingshui tunnel on the Lanzhou-Chongqing railway. Based on the analysis of their causes, relevant control measures like spoil backfilling combined with temporary supports, condulet grouting, pipe roofing, cavity plugging with C20 concrete and 0.5 m thick fine sand as well as replacing the clearance-intrusion arch were carried out. A comprehensive analysis was also conducted using the LTD ground penetrating radar (GPR) test, Midas GTS numerical simulation and monitoring and measurement, which showed that these treatments are effective with results that meet the engineering requirements. 2014 Vol. 51 (2): 172-177 [Abstract] ( 2312 ) [HTML 1KB] [ PDF 0KB] ( 481 ) 178 Discussion of the Treatment of Collapse in a Tunnel Passing Through Carbonaceous Slate FENG Ying-Jun Based on the Mohecun tunnel on the Shiyan-Tianshui expressway, this paper analyzes the causes for its collapse and compares three treatment schemes in terms of economy, safety and maneuverability. The chosen scheme, in which the lower bench is backfilled with muck; the working platform for upper bench excavation is strengthend as a protective scaffolding; reinforcement is carried out at the front and back sections of the collapse as well as at the collapsed section; sprayed concrete and a secondary lining are applied and the collapsed cavity is backfilled with concrete and dry sand, is proven to be safe, rational, economic, rapid, feasible and effective. 2014 Vol. 51 (2): 178-181 [Abstract] ( 2218 ) [HTML 1KB] [ PDF 0KB] ( 517 ) 182 Application of Grouting for Stopping Water in Shaft Excavation for Thermal Engineering DONG Shu-Mian-1, GUO Yan-Wei-2 For a shaft of a thermal power pipeline using the upside-down well wall method, the grouting technology was conducted under no dewatering and good results were obtained. Considering the hydrogeological conditions and surrounding environmental conditions, the design parameters and construction technologies of grouting are described, including the type of grout and mixture ratio, grouting pressure, grouting volume, diffusion radius, grouting-hole pattern and specific standards for groutingfinish. This project indicates that grouting solutions can effectively stop water and play a role in reinforcement through the rational design of grouting parameters and strict control of construction technology in order to accomplish safe shaft excavation and expand grouting applications. 2014 Vol. 51 (2): 182-186 [Abstract] ( 2239 ) [HTML 1KB] [ PDF 0KB] ( 505 )

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