[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   2015 Vol.52 Issue.1 Published 2015-02-25 Article 1 2015 Vol. 52 (1): 1-8 [Abstract] ( 1683 ) [HTML 1KB] [ PDF 1262KB] ( 1480 ) 9 Technical Status and Case Study on Intervention in the Shield Chamber ZHU Wei-1, 2 , Min-Fan-Lu-1, 2 , YAO Zhan-Hu-3, WANG Rui-2, WEI Dai-Wei-2, JIANG Teng-2 Encountering obstacles or excessive cutter wear in shield tunneling often result in shutdown of the shield machine, and intervention techniques are extremely critical. Based on collected documents related to this, this paper summarizes the basic concepts of intervention in the shield chamber and analyzes the application scope as well as the advantages and disadvantages of intervention at atmospheric pressure and pressurized conditions. Combined with typical cases concerning intervention in shield chambers, the experiences and technical key points are systematically summed up and future developments in China regarding interventions in shield chambers are discussed. 2015 Vol. 52 (1): 9-18 [Abstract] ( 2117 ) [HTML 1KB] [ PDF 1375KB] ( 1743 ) 19 Comparative Study of the Configuration Alternatives of a Segment Joint for a Large Deep-Buried Segmental Immersed Tunnel 吕Yong-Gang , HUANG Qing-Fei, LIU Hong-Zhou, LI Ta Abstract Using the construction of a large deep-buried segmental immersed tunnel as an example, 6 feasible alternatives are proposed for the segment joint configuration based on various arrangements of the waterproof system and shear keys. Through comprehensive comparison in terms of design, construction, and maintenance, it is determined that the optimal segement joint option is "the double waterproof system with OMEGA waterstop at the internal side + injectable waterstop embedded at the middle / shear keys at the external side." However, an appropriate option should be selected based upon the practical conditions. 2015 Vol. 52 (1): 19-25 [Abstract] ( 1885 ) [HTML 1KB] [ PDF 1031KB] ( 2460 ) 26 Study on the Construction Safety Assessment of Highway Tunnels Based on the Improved LEC Method LIU Hui, Sun-Shi-Mei Abstract The dangerous level classification for hazardous factors in highway tunnel construction can help to determine major hazard sources and to prioritize corresponding countermeasures. Based on the identification of hazard sources related to construction activities and equipments, six safety assessment units are classified: tunnel excavation, blasting, construction power supply, construction ventilation, mucking and transporting, and supporting and lining. Furthermore, the different scores and corresponding judgment clauses are determined for three indicators of C (hazard consequence), E (exposure frequce), and L(hazard likehood). Meanwile, an additional safety compensation coefficient R, with relevant judgment clauses and scores, is introduced. Regarding the above four indicators, if any judgment clause is met, whichever corresponding score of the evaluation indicator is the highest shall be taken. In this way, the LEC method is improved and five grades of dangerous level D are established. Through an applicationcase, the results show that accurate evaluation for the same hazard source is available, and the dangerous level D is closely related to the safety compensation coefficient R. This evaluation method with its general applicability is not confined to evaluating a certain assessment unit. 2015 Vol. 52 (1): 26-32 [Abstract] ( 1987 ) [HTML 1KB] [ PDF 852KB] ( 1423 ) 33 A Comprehensive Test Station Concept Concerning a Metro Structure Durability Simulation GAO Hong-Bing In light of the current state of and problems with research of metro structure durability, a theory concerning environmental simulation is introuduced to ananlyze the influential factors, influential levels of metro structure durability, and parameters for environmental simulation. A scheme for a comprehensive test station for metro structure durability is presented that can further improve the techniques of metro construction and operation maintenance. 2015 Vol. 52 (1): 33-37 [Abstract] ( 2040 ) [HTML 1KB] [ PDF 767KB] ( 1459 ) 38 Research on the Geostress State and Large-Rock Deformation of a Water Conveyance Tunnel in Pakistan BAO Lin-Hai, WANG Cheng-Hu, GUO Qi-Liang, ZHANG Yan-Shan, ZHANG Zhi-Guo Abstract It is difficult to evaluate and predict the geostress state of a construction area if no sufficient relative documents are available. Geostress is measured in three boreholes using the hydraulic fracturing method at a hydropower station in Pakistan. The characteristics of shallow geostress are obtained, and deep geostress is predicted using a variation law of lateral pressure coefficients. The test results show that: geostress increases with the depth of overburden within a range of 123~346 m, with the maximum horizontal principal stress being 4.28~13.86 MPa, and the minimum horizontal principal stress being 3.02~8.19 MPa; and the horizontal principal stress reaches 40 MPa at the maximum depth, indicating that horizontal stress is dominant at the construction site. The stress state at the construction area is evaluated by using the strength-stress ratio and Hoek-Brown rockmass strength estimaton method. The results show that the geostress of the construction site is high; the predominant direction of the maximum horizontal principal stress is NEE, which is in agreement with that of previous research work; and the current tectonic stress of the construction site has a close relationship with the collision between the India and Eurasia plates. Based on the measured geostress and predicted geostress, it is determined that large deformation of surrounding rock will occur if the overburden exceeds 300 m, and severe squeezing-induced deformation will occur if the overbuden exceeds 800 m. 2015 Vol. 52 (1): 38-44 [Abstract] ( 1974 ) [HTML 1KB] [ PDF 973KB] ( 1446 ) 45 Elastic Solution of Rock Stress and Displacement in a High-Pressure Hydraulic Tunnel Adjacent to a Karst Cavity CAI Yan-Yan-1, 2 , ZHANG Jian-Zhi-1, YU Jin-1, 2 , FU Guo-Feng-1, YU Kai-Mu-1 The stability of surrounding rocks in hydraulic tunnels under the effects of excavation and seepage is an important subject, for which the study on rock stress and displacement in high-pressure hydraulic tunnels adjacent to karst cavities is tough. In this paper, based on the elastic hypothetical theory, the karst cavity action coefficient and the complex potential theory are used to solve problems during excavation of the hydraulic tunnel adjacent to a karst cavity so that the analytical formula of rockmass stress and displacement is obtained. Each influential factor of water seepage out of the hydraulic tunnel is simplified to an axisymmetric case, and the effects of seepage fields are taken as a seepage body force acting on the stress fields. The plane strain theory is used to obtain a calculation formula to solve the water-filling problem during a normal operation period. Finally, an elastic solution is obtained by using the superposition principle. Based on the prerequisite of being in conformity with the Norway Criterion, the effects of the karst cavity action coefficient, rock-pore water pressure, and overburden are successively discussed by comparing the calculation results before and after water seeping out the tunnel. The analytical results show that the initial water filling plays a decisive role in rock stability; the increment of the karst cavity action coefficient and depth contributes to rock stability; under the influence of rock-pore water pressure, the circumferential stress field adjacent to the karst cavity presents a phenomenon of alternating higher values and lower values, which is not the case for the radial stress field; and the rock bias effect of the hydraulic tunnel adjacent to a karst cavity decreases with the increasing of the karst cavity action coefficient. 2015 Vol. 52 (1): 45-54 [Abstract] ( 2211 ) [HTML 1KB] [ PDF 1376KB] ( 1499 ) 55 Study on Rockburst Potential in Tunnels Based on the AHP-FUZZY Method and In-Situ Tests LI Bo-1, 2 , WU Li-1, 2 , LU Zhong-Le-1, 2 , LI Zhi-Gang-1, 2 , ZHOU Wei-1, 2 In this paper, the basic principle of the analytic hierarchy process and fuzzy mathematics is introduced, and the influential factors for rockbursts in tunnels are classified into six kinds of proneness factors hierarchically (C1～C6). Based on the analytic hierarchy process and fuzzy mathematics (AHP-FUZZY), the calculated results are applied to the analysis of the Shanghai-Kunming high-speed railway tunnel's proneness to rockbursts. In order to verify the accuracy of the AHP-FUZZY method in rockburst prediction, a typical tunnel section is selected to carry out the in-situ stress test, and rockburst potential is calculated and analyzed according to test data; the calculating results are in line with that of the AHP-FUZZY method. The rockbursts in the process of tunnelling are tracked and recorded, and the actual findings are identical to that of the AHP-FUZZY method and in-situ stress test, which reflects the effectiveness of the AHP-FUZZY method used for judging proneness to rockburst. 2015 Vol. 52 (1): 55-61 [Abstract] ( 1792 ) [HTML 1KB] [ PDF 920KB] ( 1429 ) 62 On the Large Squeezing Deformation Law and Classification Criteria for the Lanzhou-Chongqing Railway Tunnels in Soft and High Geostress Rocks LI Guo-Liang-1, LIU Zhi-Chun-2, ZHU Yong-Quan-2 It is commonly believed that it is inevitable for a tunnel in soft rock to incur large deformation due to squeezing under high geostress. To control tunnel deformation in squeezing rock, this paper studies the deformation law, classification criteria, and corresponding countermeasures in light of the engineering characteristics of the squeezing-rock tunnels on the Lanzhou-Chongqing railway, the analytic solutions to elastic-plastic displacement of a circular cavity in homogeneous rock, and the rock parameters specified in current Chinese railway tunnel standards. Based on the analytical results and Hoek's unsupported rock-squeezing classification criteria, and considering the effect of support resistance, it introduces classification criteria with three deformation levels, which would be determined by indicators such as the relative deformation and strength-stress ratio in the design stage. A three-level verification standard, deformation management criteria, and countermeasure during the construction stage are put forward by using deformation value and deformation rate as the classification indicators. Tunnel deformation is controlled to a certain degree with the help of the research results. 2015 Vol. 52 (1): 62-68 [Abstract] ( 1992 ) [HTML 1KB] [ PDF 1053KB] ( 1426 ) 69 Research on the Effects of Temperature on the Interaction Between Rockmass and Support YING Guo-Gang-1, 2 , ZHANG Ding-Li-1, CHEN Li-Ping-1, FANG Qian-1, YANG Wu-Li-2 The interaction between rockmass and support is one of the key topics of tunnel research since the temperature change of a concrete lining will affect the interaction between the tunnel rockmass and support: that is to say, the lining structure will expand or shrink when the temperature of the concrete lining increases or decreases due to the passive resistance caused by rockmass confinment. By means of a simplified circular tunnel analysis model, a calculation formula for the passive rock resistance varying with the lining temperature is obtained, the factors affecting the passive rock resistance are analyzed, and the measured data obtained from an existing tunnel lining replacement project are verified. The research results show that: the passive rock resistance under temperature action is a function of the lining temperature variables, lining material parameters, geometrical parameters, and rockmass material parameters, and it is available for quantitative calculation; the passive rock resistance increases rapidly in the primary stage of lining installation because of the hydration heat effect, with a peak value around 0.4MPa, while it decreases gradually with the dissipation of hydration heat. Based on the research results, a temperature correction method is available for monitoring the loosening rock pressure at site. 2015 Vol. 52 (1): 69-75 [Abstract] ( 1961 ) [HTML 1KB] [ PDF 941KB] ( 1368 ) 76 Analysis of Temperature Field Characteristics in the Jiangluling Tunnel DING Hao-1, 2 , LIU Rui-Quan-1, 2 , HU Ju-Yi-1, 2 , ZHENG Hui-Jun-3 There are few domestic reports and little literature about research on temperature field characteristics of long highway tunnels in the permafrost region, which stands over 4 000 m above sea level in the Tibetan Plateau. Therefore, a one-year field test was carried out for the inside and outside environmental temperature of the tunnel, surrounding rock, and support structure at the exit section of the Jiangluling Tunnel in Qinghai Province on the G214 National Road. Mathematical statistics were used to analyze and study the temperature variation regularity of the surrounding rock and lining structure within the scope in both the radial and longitudinal directions along the tunnel, and the environmental temperature inside and outside the tunnel was simulated and analyzed by a sine function regression method. The results show that: (1) the variation of the interrelationship of the temperature inside and outside the tunnel in permafrost regions is basically consistent with that of the longitudinal temperature distribution of the surrounding rock and lining structure in the tunnel; (2) the ridal an longitudinal temperature fields at measresment sections in tunnel are varing with the variation of the ambient temperature outside the tunnel; and(3) the radial variation range of the surrounding rock temperature of the tunnels in permafrost regions is at a depth of 2.7~3 m, but it is at a depth of 10m in the seasonally frozen regions. 2015 Vol. 52 (1): 76-81 [Abstract] ( 1960 ) [HTML 1KB] [ PDF 878KB] ( 2106 ) 82 Research on the Influence of Sprayed Concrete on the Surrounding Rock Freeze-Thaw Circle of Highway Tunnels in Permafrost Regions SHEN Shi-Wei-1, 2 , XIA Cai-Chu-1, LI Yan-3, Han-Chang-Ling-4 During tunnel construction in permafrost regions, control of the temperature field and freeze-thaw circle of the surrounding rock is the key factor for ensuring the stability of the surrounding rock and the security of the structure. In this paper, a two-dimensional unsteady temperature field model for the heat transfer of surrounding rock in light of the hydration heat of concrete is established. Based on this, the changing rules of the temperature field of the surrounding rock before and after concrete spraying are analyzed, as well as the influence of construction time and thickness of the sprayed concrete on the freeze-thaw circle of the surrounding rock. A contrastive analysis between calculated results and measured results is performed. Research results show that: the calculated data generally agrees with the measured data, with a temperature error of no more than 0.5℃ for the rock at 0.5m away from the tunnel sidewall; before sprayed concrete construction, the temperatures of the surrounding rock at different depths are slow to grow; after sprayed concrete construction, the temperature of the surrounding rock within a depth of 1m rises sharply at first, then declines, and later tends towards stabilization because of the hydration heat of concrete; furthermore, when the sprayed concrete construction is delayed 1 day or its thickness increases every 5cm, the depth of the freeze-thaw circle increases about 10cm. 2015 Vol. 52 (1): 82-88 [Abstract] ( 2102 ) [HTML 1KB] [ PDF 1042KB] ( 1422 ) 89 Study on the Characteristics of Water Pressure on the Composite Lining in Underwater Tunnels WANG Xiu-Ying, Tan-Zhong-Sheng Abstract An underwater tunnel, whether in the construction or operation phase, is always located under the water, with an unlimited water supply and constant head; thus, the water pressure is one of the main loads to be considered for the lining structure design for an underwater tunnel. In this paper, the characteristics of water pressure on composite linings in underwater tunnels are studied by a theoretical analysis, model test, and field-measured data analysis of the Xiamen subsea tunnel. The research show that: (1) when only considering tunnel drainage, the grouting circle can reduce the water pressure on the lining. Water pressure on the lining reduces with an increase of grouting thickness, and the better the grouting effect is, the more obvious the reduction in water pressure, with the higher water pressure shared by the relevant grouting circle. However, the unlimited increase of the thickness of the grouting circle has little effect on the reduction of the water pressure, so a reasonable grouting thickness is 3~8m; (2) the water pressure on the lining obviously increases with the strengthening of primary support permeability resistance. Certain water pressure on the primary support must be considered in the design, and the water pressure on the primary support is mainly dependent on the ratio of the permeability coefficient of the grouting layer to that of the primary support; and (3) the reduction coefficient of water pressure on the secondary lining depends on the discharge of water permeating into the primary lining, namely, the ratio of the water drainage of the tunnel to the volume of water permeating into the primary lining, regardless of the grouting effect and the permeability coefficient of the primary support and secondary lining. During the determination of water pressure on the secondary lining, the impact of the initial seepage field has to be considered. This research can provide a reference for the structural design of underwater tunnels and mountain tunnels with high water pressure. 2015 Vol. 52 (1): 89-97 [Abstract] ( 1996 ) [HTML 1KB] [ PDF 1157KB] ( 1494 ) 98 Research on Nonuniform Support of System Anchor Bolts ZHANG Hui-Jian-1, CHOU Wen-Ge-1, ZHAO Bin-1, GAO Yang-2 Using the four-track Wumengshan No.2 railway station tunnel as an example, a numerical simulation was performed to study nonuniform support of the system anchor bolts adopted in a multi-partition excavation. The results indicate that: under uniform support of the system anchor bolts, the order of axial force magnitude is "spandrel (partition ① and ②) > arch springing (partition ④ and ⑤) > sidewall (partition ⑥ and ⑦) > crown (partition ③)," with obvious nonuniformity at different excavation partitions; the axial force on the left and right sides of the anchor bolts at the arch springing and sidewall are asymmetrical, i.e., it is larger at the former excavated side than it is at the latter one; the axial force of the anchor bolts is minimal at the crown and has almost no effect. An analysis of nonuniform support of the system anchor bolts is carried out based on different lengths, diameters, and intervals of anchor bolts, and comparison is undertaken with the uniform support. Based on the results, consumption of the anchor bolts is 37%, 36%, and 36.93% of the original consumption at the spandrel, arch spring, and sidewall and crown, respectively, thereby achieving significant economic benefits. 2015 Vol. 52 (1): 98-104 [Abstract] ( 1970 ) [HTML 1KB] [ PDF 941KB] ( 1357 ) 105 Analysis Model for the Early Performance of in a Factory Immersed Tunnel Elements LIU Xin-1, LIU Xian-1, JIANG Wei-2, YUAN Yong-1, SU Quan-Ke-3 Due to the effects of material properties, structural design, construction technology, etc., immersed tunnel elements are vulnerable to cracking at the early stage of prefabrication, which may be harmful to their serviceability and durability. In this paper, using the immersed tunnel of the Hong Kong-Zhuhai-Macao Bridge Project that is currently under construction as an example, an analysis model is established regarding the early-stage performance of immersed tunnel elements prefabricated in a factory and is verified by a full-scale test. Based on an analysis of the structural performance under the standard construction process, a development law is obtained for the early-stage performance of immersed tunnel segments, and the rationality of the crack-risk index is studied for controlling the early-stage cracking. 2015 Vol. 52 (1): 105-113 [Abstract] ( 1904 ) [HTML 1KB] [ PDF 1340KB] ( 1333 ) 114 Research on Similar Materials for a Large Immersed Tunnel Model Test HU Zhi-南, XIE Yong-Li, LAI Hong-Peng To research the mechanism of the segment joint of an immersed tunnel under uneven settlement and load, the similarity ratio of a relevant model test was determined regarding the dimension of the test platform, and the similarity criteria was deduced based on the similarity theorem. Regarding the similar material selection, a low-grade cement with a high water-cement ratio and sand ratio, an aggregate with a low elastic modulus, bentonite, polypropylene fiber, and fly ash were adopted to prepare a strong mixture with a low elastic modulus, whose mix ratio was determined via a test. Furthermore, a mechanical test was carried out with a universal press machine, strain gauge, and extensometer for the specimen's strength and elastic modulus. According to the mix ratio test, a similar concrete material with an elastic modulus less than 10 GPa and strength greater than 8 MPa can be produced by adjusting the content of bentonite, whose mechanical behavior is as stable as that of the normal concrete. 2015 Vol. 52 (1): 114-118 [Abstract] ( 1797 ) [HTML 1KB] [ PDF 689KB] ( 1371 ) 119 Influence of Key Parameters of a TBM Gauge Disc Cutter on Rock-Breaking Efficiency WU Yuan-1, XIA Yi-Min-2, GUO Jin-Cheng-3, YANG , KAI 2, LIN Lai-Kuang- 2, ZHU Xiang-Heng-2 Rock-breaking efficiency is a key indicator for measuring the performance of a disc cutter. In this paper, a rock-breaking simulation model of the gauge disc cutter is established based on the discrete element method, and rock-breaking tests of the gauge disc cutter are performed through the multi-factor orthogonal design method. Meanwhile, by taking rock-breaking efficiency as the evaluation indicator for rock-breaking performance of the gauge disc cutter, it studies the effects of the angle of the cutter blade, width of the blade tip, installation angle, and transition radius of the cutterhead on rock-breaking efficiency, as well as the effects of each of those factors on marble breaking and concrete breaking respectively. It is thought that the effects of the installation angle on rock-breaking efficiency are significant, less so for the transition radius of the cutterhead and angle of the cutter blade, and minimal for the width of cutter blade. The effects of each factor on rock-breaking efficiency are different for different rock types. Effects of the installation angle and transition radius on marble- and concrete-breaking efficiency are the same, while the effects of the angle and width of the blade tip are opposite of each other. Experiments show that rock-breaking efficiency increases by 80% when the installation angle is adjusted from 8° to 4°, verifying the rule that the effects of the installation angle of the gauge disc cutter are significant on rock-breaking efficiency. 2015 Vol. 52 (1): 119-126 [Abstract] ( 2094 ) [HTML 1KB] [ PDF 1079KB] ( 1453 ) 127 Analysis of the Influential Factors of and 3D Analytical Solution for Ground Deformation Induced by Shield Tunnelling JIANG An-Long In this paper, using a shield tunnel in water-rich sandy ground as the study object, a mechanical model of shield thrust is established, with a focus on five influential factors, i.e., front additional thrust, friction force between the cutterhead and soil mass, friction force between the shield shell and soil mass, ground loss, and synchronous grouting pressure at the shield tail. Based on the Mindlin solution, a 3D analytical solution to ground deformation, which considers the influence of synchronous grouting pressure and cutterhead friction force, these factors are derived and verified by in-situ monitoring data and numerical analytical results. Analytical results show that curve of transverse ground deformation by shield tunneling presents in a "V" shape and the curve of the longitudinal deformation is an "S" shape, the left and right sides of the ground deformation curves concerning the friction force between the cutterhead and soil mass are antisymmetric, and ground heaving may occur due to synchronous grouting pressure at the shield tail and can be effectively controlled in time by grouting under the appropriate grouting pressure. The results obtained from this study are reasonable and suitable for predicting ground deformation during shield tunnelling. 2015 Vol. 52 (1): 127-135 [Abstract] ( 1908 ) [HTML 1KB] [ PDF 1252KB] ( 2409 ) 136 Prediction and Control Techniques for Building Settlement Induced by Large-Diameter EPB Shield Tunnelling SUN Chang-Jun-1, 3 , ZHANG Ding-Li-1, GUO Yu-Hai-2, MA Xiao-Wei-3 Based on the construction practice of a large-diameter EPB shield first adopted for Beijing Metro Line 14, the building settlement induced by shield tunneling is predictied by numerical simulation and a comparative analysis of predicted and measured data is carried out. The results show that: the settlement and inclination of buildings are within control standards and the design and construction scheme is feasible; the settlement at the shield tail is 30% to 50% of the maximum settlement and it is a critical factor to control; the grouting via the embedded pipes on the ground is an effective auxiliary measure to control settlement; the key points to control settlement during shield construction include improvement of the plastic flow properties of the soil mass, control of driving parameters, extracted muck volume, simultaneous grouting at the shield tail, and secondary grouting. 2015 Vol. 52 (1): 136-142 [Abstract] ( 1859 ) [HTML 1KB] [ PDF 1009KB] ( 2451 ) 143 Prediction of Ground Settlement Induced by Metro Shield Construction Based on the Modified Peck Formula FANG 恩Quan-1, YANG Ling-Zhi-1, LI Peng-Fei-2 Ground settlement caused by shield construction for metro tunnels should be given more attention in the field of rail transit. Based on a subway project under construction for the Guangzhou Metro, the rules of transverse and longitudinal ground settlement during shield construction are studied. A prediction model using the interpolation method and least square method based on the Peck formula is established. Prediction results of the model applied in an information system showed that ground settlement could be well predicted with this model on the premise of non-extremum of settlement, providing a reference for engineering practice and theoretical research． 2015 Vol. 52 (1): 143-149 [Abstract] ( 2108 ) [HTML 1KB] [ PDF 968KB] ( 2182 ) 150 Shield Construction Control Based on the Functional Requirements of Concrete Pavement in an Airport Flight Zone ZHANG Hong-1, 2 , Ling-Jian-Ming-3 In light of transverse slope requirements of airfield runways and the curved pattern of foundation settlement sections, a formula, which can be used to control the counter slope phenomenon induced by shield driving under pavement structures in the flight zone, is derived based on a assumption of compatible deformation between the pavement structure and foundation settlement. An allowable value [δmax /i] is also derived, with which no counter slope phenomenon can occur under differential settlement. The parameters involved in these formulas can be used to guide shield construction and reduce the possibility of the counter slope phenomenon in airfield runways. 2015 Vol. 52 (1): 150-155 [Abstract] ( 1900 ) [HTML 1KB] [ PDF 823KB] ( 1373 ) 156 Influence of Foundation Pit Excavation Approaching a Metro Station GUO Dian-Ta-1, 2 , Zhou-Cui-Ying- 1 Based on a pit excavation near a metro station in Guangzhou, a series of 2D nonlinear calculation models considering the interaction of the metro station, surrounding soils, and the foundation pit retaining structure are established by finite element software. The influence of pit excavation on the deformation and dynamic response of the metro station under different intervals and excavation depths is studied. The results indicate that the deformation distribution of the station has obviously been changed due to the adjacent excavation. The closer and deeper the excavation is, the more obvious the effects on the station are. The deformation of the station mainly indicates vertical uplift and movement towards the internal side of the foundation pit. With an increase of excavation depth, horizontal displacement of the station changes obviously, and the vertical displacement changes a little, while the differential displacement has changes a lot, significantly affecting the structure. With an increase of excavation depth and a decrease of interval distance, the vibration response of both the foundation pit support structure and the station is affected, which further aggravates the structure vibration. Finally, the technical countermeasures to control deformation of the station structure are presented, providing a reference for similar projects in the design and construction phases. 2015 Vol. 52 (1): 156-162 [Abstract] ( 1885 ) [HTML 1KB] [ PDF 977KB] ( 1346 ) 163 On the Velocity Law of Ground Particle Vibration Induced by Cut Blasting in a Shallow-Buried Tunnel SUN Zhi-Guo, Wang-Xiao-Wen Based on the construction of lot 3 of the Qingdao Metro Line 3, which passes under a dental hospital, this paper researches the velocity law of ground particle vibration induced by cut blasting in a shallow-buried tunnel. To be specific, it monitors the maximum vibration velocities in the vertical, horizontal radial, and horizontal tangential directions at the first monitoring section from right above the parallel tunnel axis, as well as the maximum velocity in the vertical direction from the vertical tunnel axis. In light of the effects of underground blasting on ground vibration, it is determined that the vibration peak value occurs at a distance of 1~3m from the working face, while a crater-shaped peak and valley value occur near the reference point due to cut blasting, and the synthetic vibration velocity is greater than the velocity in any single direction, but their vibration laws are similar. 2015 Vol. 52 (1): 163-167 [Abstract] ( 1894 ) [HTML 1KB] [ PDF 652KB] ( 1365 ) 168 Anaysis of Construction Techniques for a Metro Tunnel Approaching an Existing Station WAN Liang-Yong-1, SONG Zhan-Ping-2, 3 , QU Jian-Sheng-2, 3 , SONG Yun-Cai-3 Construction of a new metro tunnel approaching an existing metro station may cause deformation of the station structure, affecting normal operation of the metro. Based on Beijing Metro Line 7 passing under the Shuangjing Station of the existing Beijing Metro Line 10, a numerical simulation was carried out regarding the deformation and force applied to the station's main structure, the metro track support of the running tunnel due to full-face tunnel excavation, and the bench method excavation and CRD excavation of the metro running tunnel approaching the existing station. A contrastive analysis was undertaken regarding the deformation characteristics of the existing station and track under different excavation schemes, and an excavation scheme was determined for the running tunnel approaching the existing station considering deformation control and force variation factors. A numerical simulation was performed aimed at the reinforcement effect for deformation control of the existing station and track under different reinforcement measures when the CRD method was used, and parameters of grouting reinforcement were determined, such as reinforcement scope and length. Analysis of site monitoring results shows that the optimized CRD construction method and reinforcement measures, such as reinforcing the interbed between the left line and right line, the stratum at the working face, and the area within 3m outside the left and right external contour, can guarantee the safety of the existing station. The deformation rate of the existing track is no more than 0.04 mm/d and the accumulated deformation of the main structure of the existing station is less than 10mm. 2015 Vol. 52 (1): 168-176 [Abstract] ( 1995 ) [HTML 1KB] [ PDF 1400KB] ( 1321 ) 177 Construction of a Railway Tunnel in Water-Rich Tertiary Sandstone QI Wei-Hua The Cheng-er-shan tunnel is mainly located in water-rich tertiary sandstone, and plastic flow deformation could occur if the rockmass is disturbed due to poor stability. In this paper, the nature of tertiary sandstone, and the pros and cons of the construction methods adopted in the early stage are analyzed and summarized; a concept of "dominant dewatering, supplementary grouting, heavy support, and rapid sealing" is raised in terms of the design and construction; and such construction measures as advance dewatering, advance pre-support, double-layer primary support, and secondary lining are described in detail. 2015 Vol. 52 (1): 177-183 [Abstract] ( 1873 ) [HTML 1KB] [ PDF 994KB] ( 1571 ) 184 Analysis of Ground Responses to Shield Shutdowns in Soft Clay LIANG Rong-Zhu-1, 2 , XIA Tang-Dai-1, 2 , LIN Cun-Gang-3, 4 , Wu-Hao-5, YU Feng-6 Based on two shutdowns of the EPB shield during construction of a Hangzhou metro running tunnel in soft ground, the law of ground deformation during the stoppage is investigated. The results indicate that: the affected settlement scope is more than 5 times the shield diameter and much higher than 3 times under normal driving conditions; settlement of the soil mass in front of the shield develops as a whole, and its settlement trough does not fit the Peck normal distribution formula; the total thrust of jacks increases sharply when the shield driving restarts as compared to normal driving. It is thought that disturbed structural clay recovers its strength during the shutdown time, and this results in a substantial increase of friction between the shield skin and soil mass. 2015 Vol. 52 (1): 184-189 [Abstract] ( 1892 ) [HTML 1KB] [ PDF 884KB] ( 2161 ) 190 Shallow-Buried Large-Section Soil Tunnel Passing Under the Great Wall of the Ming Dynasty LAI Hong-Peng-1, 2 , TI Jia-Feng-3, ZHANG Hong-Guang-1, XIE Yong-Li-1 Aimed at the construction difficulties of the Xihekou shallow-buried large-section tunnel that passes under the Great Wall of the Ming dynasty, this paper proposes a comprehensive safety control technology, i.e., pre-reinforcement by cement-water-glass grouting on the ground and a double-layer pipe-roof support in the tunnel; construction by double-side drift with a short bench; and locally optimizing the support parameters. Based on a model test, the feasibility of the scheme was verified and control standards of ground settlement were determined. Scheme rationality was assessed in light of field monitoring. 2015 Vol. 52 (1): 190-196 [Abstract] ( 1877 ) [HTML 1KB] [ PDF 1178KB] ( 2292 ) 197 Application of Advance Geologic Prediction to the Observational Construction of Railway Tunnels LIAO Yan-Kai-1, Dai-Jian-Ling-2, WU Zhi-3, Guo-Ru-Jun-1 Because of the complicated geological conditions of tunnels, the geological conditions determined in preliminary investigation and design are often different from those found during actual excavation, which cannot meet the requirements for accurate, real-time geological information for tunnel construction. In this paper, the Xingutian tunnel is taken as a project example to introduce the concept of dynamic design applied in railway tunnel construction. Combining the advance geologic prediction technique with geological field surveys, the classifications of surrounding rocks in front of the tunnel can be modified in time, and the original design option can be adjusted dynamically, allowing the corresponding construction and supporting methods to be adjusted in time so as to ensure the safety and economy of construction. 2015 Vol. 52 (1): 197-202 [Abstract] ( 1835 ) [HTML 1KB] [ PDF 832KB] ( 2324 ) 203 Application and Analysis of Hydrostatic Level Gauges in Deformation Monitoring of Subway Tunnels During Operation SUN Ze-Xin-1, ZHANG Shu-Feng-2, LIU Ning-1 This paper states the basic operation principles of a hydrostatic level gauge and the factors influencing monitoring accuracy in a subway tunnel during operation. Combined with a monitoring case of a hydrostatic leveling system in an operational metro tunnel during construction of a foundation pit, the monitoring accuracy of the hydrostatic level gauge during a train shutdown is contrasted with that of train normal operation in order to analyze the influence of train operation on monitoring accuracy. Meanwhile, the reliability of the hydrostatic level system is verified by comparison with the manual monitoring data. The results show that the automatic monitoring system can meet the requirements of real-time monitoring accuracy for subway tunnel deformation during operation. 2015 Vol. 52 (1): 203-208 [Abstract] ( 2161 ) [HTML 1KB] [ PDF 954KB] ( 2033 )

More>>   · · More>>

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