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Quick Search     Advanced Search MODERN TUNNELLING TECHNOLOGY   2017 Vol.54 Issue.3 Published 2017-06-25 Article 1 On Design Issues of Reinforcement of the Secondary Lining of High-Speed Railway Tunnel YANG Jianmin1 TAN Zhongsheng2 In order to study the necessity of reinforcement of high-speed railway tunnel secondary linings, and the consistency between the reinforcement design values and actual stress states of reinforcements, the Chinese, German and Japanese standards are compared. Based on the Zhengzhou-Xi′an high-speed railway tunnel projects, the comparative analysis is conducted regarding the design parameters of secondary lining reinforcement and the actual reinforcement stress states in deep and shallow buried tunnels. The results show that: 1) the design of secondary lining reinforcements would be conservative at 50% ~ 60% of the rock loads as stipulated in the specification and the most unfavorable nodes, so there is a big difference between the field measured reinforcement stress values and the designed ones; 2) only the reinforcements at the inner layer of the vault lining are in tension, with tension values of 19.5 MPa; the rests are in compression with small pressure values, and the maximum pressure of the secondary lining reinforcements is 57 MPa at the left and right side walls; 3) in checking the secondary lining structure, the pressure of the surrounding rock can be appropriately reduced; and 4) the lining reinforcements should be determined by engineering analogy and combined with the formula stipulated in the specification. 2017 Vol. 54 (3): 1-7 [Abstract] ( 1324 ) [HTML 1KB] [ PDF 0KB] ( 567 ) 8 Research on the Design Parameters of a Single-Track Railway Tunnel Lining under Local Water Pressure The high local water pressure applied on tunnel linings is one of the main reasons for lining cracking af? ter operation. To address the insufficient theoretical design basis for linings that are subject to local water pressure,field tests and a numerical simulation method were used to study the mechanical characteristics and safety behaviors of linings under local water pressure in terms of the standard design drawings of a single-track railway tunnel,namely a curved wall with the floor in grade Ⅱ rock and a curved wall with the invert in grade Ⅲ rock. The effects of the measures to improve lining safety were analyzed, and the design parameters for the lining under local water pressure were put forward. The results show that: 1) the distribution of safety factors at various lining parts is much more scattered in the case of local water pressure, with the lining part subjected to local water pressure being the weak point; 2) the safety of the reinforced concrete lining can be improved by increasing the lining thickness and the amount of reinforcement rather than increasing the concrete grade; and 3) the safety of the curved wall with an invert is obviously better than that of the curved wall with a floor. By increasing the lining thickness and the amount of reinforcement, the lining structure of the curved wall with a floor and the curved wall with an invert can bear a water pressure of 0.2 MPa and 0.5 MPa, respectively. In the case of higher water pressure, it is recommended to increase the curvature of the curved wall to improve the lining safety. 2017 Vol. 54 (3): 8-16 [Abstract] ( 1106 ) [HTML 1KB] [ PDF 0KB] ( 484 ) 17 Long-Term Monitoring and Analysis of Lining Cracks in Operating Highway Tunnels Cracks are generally distributed in the linings of operating highway tunnels, for which stability directly affects the operational safety of the tunnels. Monitoring tools are an intuitive and effective method for analyzing and predicting the development of cracks. However, because there is a lack of monitoring documentation regarding lining cracks, the following study was carried out based on a second-class highway tunnel: the lining crack distribution laws were analyzed from 3 aspects—crack types, location and surrounding rock grades of cracks and geometric features of cracks—and 12 selected typical lining cracks have been monitored for 2 years using fiber grating sensors.The monitoring results show that the lining crack development laws can be divided into 4 types: stable, periodically changing, increasing and closed. Most of the cracks are correspondingly stable and controllable based on the monitoring data of the crack′s geometric features, which slightly affects the stability of tunnel structure. After systematic analysis of the causes of tunnel lining cracks from the aspects of survey and design, construction and operation management, countermeasures for the tunnel lining cracks are proposed. The treatment principle of“monitoring first, followed by classification and then selection of treatment measures”is suggested to treat the lining cracks. The results provide a useful reference for the assessment and treatment of cracks in similar tunnels both at home and abroad. 2017 Vol. 54 (3): 17-25 [Abstract] ( 1220 ) [HTML 1KB] [ PDF 0KB] ( 541 ) 26 Study of Rockburst Characteristics of Bedded Surrounding Rock in Deep and Long Tunnels Based on the long and deep Erlang Mountain tunnel , 3DEC software was used to build a numerical mod? el with different dip angles, inclinations and thicknesses of the bedded surrounding rock, and the principal stress of each position at the tunnel periphery was calculated so as to judge the rockburst position during tunnel construction.The results show that: 1) when the dip angle of the surrounding rock is 0° or the inclination of the stratified rock is the same as the tunnelling direction, the principle stress at the vault crown position is the largest; 2) when the rock dip angle is 90°, the two side walls are prone to rockburst; 3) when the rock inclination is opposite to that of the tunnel excavation, the principal stress at the upper part of the working face is the largest, where it is prone to rockburst; and 4) the thickness of the bedded rock does not affect the position of the maximum principal stress. 2017 Vol. 54 (3): 26-31 [Abstract] ( 1148 ) [HTML 1KB] [ PDF 0KB] ( 489 ) 32 Analysis of the Interference Waveform Characteristics of Ground Penetrating Radar (GPR) for Tunnel Engineering Ground Penetrating Radar (GPR) has been used widely in tunnel engineering, however, interference fac? tors are often encountered in the process of tunnel detection that lead to abnormal reflection waveforms covering the effective waveforms, which seriously affects the subsequent interpretation work. In this paper, the interference factors encountered in tunnelling detection are divided into three types, e.g., the coupling interference, construction interference and interference in special circumstances; the waveform characteristics of GPR interference waves are analyzed and effective treatment measures for inhibiting GPR interference factors are put forward, ensuring effective interpretation and identification of the interference waveforms and accurately avoiding the misjudgment of GPR interference waveforms. 2017 Vol. 54 (3): 32-36 [Abstract] ( 1133 ) [HTML 1KB] [ PDF 0KB] ( 476 ) 37 Application of a Remote Real-Time Monitoring System in an Open-Cut Tunnel Focused on an open-cut tunnel structure near a landslide site on the Sichuan-Guizhou railway, a re? mote real-time monitoring system was applied to constantly monitor the rock stress, reinforcement stress and concrete stress. The monitoring system has such functions as data collection, remote data transmission, real-time display by data curves, monitoring and early-warning, etc. The monitoring data of the open-cut tunnel indicate: when the filling in of the soil above the open-cut tunnel is completed, the structural internal force tends to be stable along with a decrease of construction loading and a consolidation of the soil mass; additionally, the reinforcements and concrete on both side walls of the open- cut tunnel is presented as being tensioned outside and compressed inside,which means the structure is affected by an unbalanced pressure, and this conforms to the actual situation. Engineering practices show the force applied on an open-cut tunnel structure can be known in a timely manner by the realtime monitoring system, while the normal operation of the existing railway won′t be affected—thus it is suitable for the long-term monitoring of an open-cut tunnel structure during operation. 2017 Vol. 54 (3): 37-41 [Abstract] ( 1125 ) [HTML 1KB] [ PDF 0KB] ( 503 ) 42 Longitudinal Equivalent Continuous Model of a Shield Tunnel Based on the Ellipse Form In light of the situation where the deducted tunnel longitudinal stiffness effective rate (0.14~0.23) was smaller than the adopted value (about 0.7) of a shield tunnel in Shanghai, the traditional longitudinal equivalent continuous model was improved, and a new longitudinal equivalent continuous model was established that corrects the calculation formula for the eqnivalent bending rigidity based on the parameter equation for the ellipse and the consideration of the effect of lateral rigidity and influential scope of the annular joints, furthermore the constraint coefficent of soils and influence coefficent of segment eretion types were taken into account in the formula. Taking a specific tunnel in Shanghai as an example, the influence of lateral rigidity and the influential scope coefficient of the an? nular joint on the equivalent bending-resistant stiffness was analyzed. The calculation results show that assuming that“ellipse deformation”occurs in the tunnel, the effective rate of the longitudinal equivalent stiffness increases by 26%~50% compared with that by another models. The data were close to the actual application values and the rationality of the ellipse assumption was verified. 2017 Vol. 54 (3): 42-49 [Abstract] ( 1044 ) [HTML 1KB] [ PDF 0KB] ( 482 ) 50 Dual-Stage Multi-Strategy PSO-BP Model for Tunnel Cavern Foundation Stability Many factors affect the stability of a tunnel cavern foundation; there is a complex nonlinear relationship between these factors and the tunnel cavern foundation stability, and conventional methods have difficulty describing this complex relationship. Therefore, a dual-stage multi-strategy particle swarm optimization (DMPSO) BP neural network model is proposed for evaluating the stability of tunnel cavern foundations. The particle swarm algorithm is characterized by a strong capability for global optimization and a high search efficiency, with these characteristics being more prominent after improvement of the algorithm. The BP algorithm has a strong capacity for nonlinear mapping and generalization, with the disadvantages of slow convergence and local optimization. By using the dual-stage multi-strategy particle swarm optimization (DMPSO) to determine the weights and thresholds of the BP neural network, the shortcomings of the BP neural network are solved and the prediction accuracy is improved. Using the Chongqing Xiaoshizi station cavern foundation as an example, the feasibility of the dual-stage multi-strategy particle swarm optimization BP neural network model (DMPSO-BP) is verified, with the prediction accuracy of the proposed model being better than that of the fuzzy neural network model and particle swarm optimization BP neural network (PSO-BP) model. 2017 Vol. 54 (3): 50-57 [Abstract] ( 1094 ) [HTML 1KB] [ PDF 0KB] ( 474 ) 58 Analysis of Internal Forces and Deformations of Retaining Piles Considering Mechanical Properties of the Pile-Soil Interface Using the deep foundation pit project of Bagou station of Beijing metro line 10 as an example, and con? sidering the mechanical properties of the pile-soil interface, a three-dimensional finite difference model was built,and the internal force and deformation of the retaining piles were analyzed, as compared with the monitored data.Furthermore, the effects on the internal force and deformation of the retaining piles caused by the soil frictional angle and the friction coefficients of normal and tangential coupling springs of the pile-soil contact interface are discussed. It is concluded that the bending moments and horizontal displacements of the retaining piles decrease with the increase of the soil frictional angle, and the influence degree diminishes gradually; both the maximum bending moment and horizontal displacement increase at first and then remain invariant with the increase of the friction coef? ficient of the normal coupling spring, while the friction coefficient of the tangential coupling spring has little effect on them. This conclusion provides a reference for the design and calculations of retaining structures with similar deep foundation pit projects. 2017 Vol. 54 (3): 58-64 [Abstract] ( 1097 ) [HTML 1KB] [ PDF 0KB] ( 463 ) 65 Influence of Shield Shell Friction on Surrounding Soil Mass Properties Based on the left line of the shield running tunnel from Dongnanjiao station to Jianguo station on the Tianjin Metro line 2, a calculation of surface settlement induced by shield driving was carried out by ABAQUS, and verification was performed on the basis of measured results to further analyze the influence of different shield shell frictions on the deformation and force of the surrounding soil mass during shield driving for a certain thrust of the work face. The results show that the horizontal displacement and additional stress toward the direction of driving are greatly influenced by the function of the shield shell friction, especially at the most sensitive section at the shield head and near the shield tail; when the distance from the tunnel is equivalent to the tunnel length or greater, the additional stress of the soil mass due to shield shell friction decreases and can be disregarded. 2017 Vol. 54 (3): 65-72 [Abstract] ( 1175 ) [HTML 1KB] [ PDF 0KB] ( 485 ) 73 Experimental Study on Steel Pipe Pile Reinforcement of the Soft Foundations of Saturated Loess Tunnels As for the reinforcement measures for the soft foundation of saturated loess in the Wangjiagou tunnel on the Baoji- Lanzhou passenger dedicated line, laboratory tests containing 4 kinds of loess water content and field tests for reinforcing the soft foundation were conducted. The settlement characteristics of the model pile and the field single pile and composite foundation were analyzed, respectively, and the strain characteristics of the modelpile were studied for the high water content of the loess. Conclusions could be summarized as follows: Q-S curves of the model piles change from a smooth shape to an abrupt shape with the increase of the moisture content in the soil around the pile, while the settlement rate of the pile becomes higher, and the ultimate side friction of the pile decreases, as the law of the power function. For the high water content of loess, the strains along the steel pipe pile distribute in a“B”shape with the loading time. Based on the results of field tests, it is suggested that the steel pipe pile and composite foundation should be used for reinforcing the soft foundation of the Wangjiagou saturated loess tunnel, with steel pipe piles distributed as an equilateral triangle. The proposed design parameters for the piles are given according to the specifications. The experiment results provide a reference for laboratory tests and field tests of soft foundations reinforced by steel pipe piles. 2017 Vol. 54 (3): 73-81 [Abstract] ( 1069 ) [HTML 1KB] [ PDF 0KB] ( 501 ) 82 Analysis of Mechanical Behaviors during Shield Launching Shaft Cross Passage Construction in Soil/Rock Mixed Ground Facing the special "soil/rock" mixed ground condition in the Changchun area, the monitoring data of ground surface settlement and the convergence deformation during cross-passage construction were analyzed, and the settlement and deformation laws were obtained during the construction process using the CRD method. Then, a numerical simulation was conducted using MIDAS/GTS finite-element software to study the settlement, deformation and mechanical behaviors of the support structure and buried pipelines during cross-passage excavation. After a comparison with the measured data, some results were determined: 1) ground surface subsidence induced by the excavation of pilot tunnels 1~4 accounts for 74% of the total settlement; 2) the influence scope caused by tunnel face excavation is around 15 m ahead of and behind the face; 3) the Mises stress in the vault and invert of the primary support structure is high, and the stress concentration emerges at the junction of the primary support structure; and 4) the maximum Mises stress is in the middle of the pipelines with the lowest stress point being about 10 m away from the axis of the pipeline. 2017 Vol. 54 (3): 82-89 [Abstract] ( 1033 ) [HTML 1KB] [ PDF 0KB] ( 515 ) 90 Numerical Analysis of the Transverse Dynamic Response of Mountain Tunnels Subjected to an Oblique Incidence of Earthquake Waves The significant characteristic of a near-fault earthquake is its directivity effect, therefore, the influence of non-uniform excitation induced by an oblique incident earthquake on a tunnel structure should not be ignored.Based on the wave numerical simulation theory of a viscoelastic artificial boundary, a numerical analysis of the transverse seismic response of a mountain tunnel was carried out with the Wenchuan Wolong earthquake wave using ANSYS, and the influence of the incident angle on the lining dynamic response was studied. The results show that: the dynamic responses of the lining structures subjected to the oblique incidence of seismic waves are quite different from those subjected to the vertical incidence of seismic waves, and they present the characteristics of being vertical? ly loaded, with a structure response that increases with an increase of the incident angle; and in the case of oblique incidence, weak parts of the lining are at the crown, haunch and arch spring. 2017 Vol. 54 (3): 90-96 [Abstract] ( 1051 ) [HTML 1KB] [ PDF 0KB] ( 476 ) 97 Influence of a Random Block on the Stability of the Underground Power House of the Taishan Pumped Storage Power Plant The overall stability of an underground cavern is determined by the stability of a key block of rock mass, and it is critical to determine the location, size and instability mode of the key block in order to control and predict tunnel safety. The surrounding rock of the Taishan pumped storage power station underground workshop is cut by a discontinuous plane and has problems related to stability. Based on the probability characteristics of the joint crack orientation, the maximum failure mode was determined using stereographic projection; the key block positions of the workshop were determined, the long-term stability was forecasted and the quantitative index for the key block safety was given. Combining the strength reduction method with key block theory, the long-term stability and risks of the underground plant were effectively forecasted. 2017 Vol. 54 (3): 97-104 [Abstract] ( 1117 ) [HTML 1KB] [ PDF 0KB] ( 466 ) 105 Key Block Determination in the Progress of Design and Construction of the Diaoyutai Tunnel in Complex Surrounding Rock The stability and safety of a jointed rock tunnel is controlled by key blocks to some extent. It is impor? tant to avoid engineering accidents by making sure that key blocks are determined in a timely manner in the progress of design and construction. Based on the block theory and in-site monitoring, and using the design and construction of the Diaoyutai tunnel as an example, unlocated blocks, located blocks and random blocks are searched for and determined by the self-developed GeoSMA- 3D system. The stability of the tunnel blocks is also studied.For studying the unlocated blocks, the theoretical calculation method for the possible maximum key block on the excavation face is determined for three structural planes. For studying the located blocks, the key block on the excavation face is sought based on information regarding deterministic structural planes. For the study of random blocks,the random structural planes are obtained by a three-dimensional contact-free measuring system. The finite blocks and key blocks are sought for under the interaction of deterministic structural planes and random structural planes. The three different kinds of block analysis method are inter-complementary, providing the basis for engineering design and construction from different aspects. 2017 Vol. 54 (3): 105-111 [Abstract] ( 1048 ) [HTML 1KB] [ PDF 0KB] ( 476 ) 112 Numerical Analysis of the Sensitivity of Deformation Caused by a Super Shallow-Buried Tunnel Passing under an Existing Railway The super shallow-buried running tunnel between Xianlinhu station and Huashu station of Nanjing sub? way line 4 passes under the dedicated railway of the Jiangnan Cement Plant, and the requirements for ground deformation control are relatively high. The karst is developed and the lithology is unfavorable at this section, and it causes great risks during construction. Based on the actual geological and construction conditions, an analysis model was established using ABAQUS to study the surface settlement and subgrade deformation caused by tunnel construction under two cases: the subgrade load and intermittent function of the subgrade load are considered and not considered before and after the grouting reinforcement of the soil mass. A comparison was carried out regarding the analysis results and monitoring data. The results show that the numerical analysis results are correct and the construction technology guarantees smooth construction of this project. 2017 Vol. 54 (3): 112-119 [Abstract] ( 1208 ) [HTML 1KB] [ PDF 0KB] ( 486 ) 120 Characteristics of Ground Deformation Induced by Large-Diameter Slurry Shield Construction Based on the large-diameter (?14.5 m) double-tube river-passing shield tunnel at Weisalu of Nanjing city and on-site monitoring data acquired there, the process and distribution law of surface deformation induced by the construction of a large-diameter slurry shield in sand and sandy cobble strata was studied. The results indicate that vertical surface deformation of the shield tunnel includes four stages: heaving, rapid settlement, slow settlement and stabilization. Surface deformation of single-tube tunnel construction can be described by the Peck formula, with an average Vl value of 1.856% and K value of 0.423 by fitting a unimodel shape; Surface deformation of the doubletube tunnel is of a bimodal asymmetrical shape since the later tunnel construction causes the maximum surface settlement and the trough width to increase, thus the trough shape is changed. Surface deformation of the double-line tunnel can be described by a double Peck formula, and there is no obvious correlation between the K value and the number of tunnels and the construction history, and the Vl value is related to the construction method, quality management and construction procedure. 2017 Vol. 54 (3): 120-125 [Abstract] ( 1271 ) [HTML 1KB] [ PDF 0KB] ( 460 ) 126 Numerical Analysis of the Influence of a Cavity behind the Shield Lining on the Tunnel Structure A numerical analysis of the influence of a cavity behind the lining of a shield tunnel was performed in respect to the position and size of the cavity based on the water inflow of a running tunnel on the Xi′an metro using ANSYS software. The results show that: 1) the contour line of the stress concentration factors (SCF) is presented in a butterfly shape—with the largest stress concentration at the top and bottom of the tunnel and the smallest ones at the two side—if there is no cavity behind the lining; 2) if the cavities behind the lining are located at the two sides, it has a significant impact on the stress concentration of the surrounding rock, internal force and safety factor of the segment and the impact decreases with the movement of the cavity toward the top and bottom of the tunnel; 3) with an increase of distance from the cavity, the impact on the stress concentration of the surrounding rock, internal force and safety factor decreases; 4) axial force is less affected by the cavity size while the segment bending, stress concentration of the surrounding rock and safety factor are much more affected by the cavity size; and 5) with an increase of the cavity area, the impact of the cavity on the stress concentration of the surrounding soil mass, internal force and safety factor of the segment increases. 2017 Vol. 54 (3): 126-134 [Abstract] ( 1078 ) [HTML 1KB] [ PDF 0KB] ( 476 ) 135 Local Dynamic Response of a Masonry Structure to the Vibrations of Tunnel Blasting Based on the New Hongyan tunnel of the Chengdu- Chongqing Passenger Dedicated Line, a typical blasting vibration wave and a two-layer masonry structure were selected to analyze the low-order integrated mode and high-order local mode of the masonry structure. The characteristics of displacement and the stress response of the structure to vibrations during tunnel blasting were studied using the modal displacement superposition method.The distribution and variation of the principal tensile stress of brick walls under different particle peak velocities were calculated. The results show that for a typical two-layer masonry structure, the first five stages are of a low-or?der integrated mode with natural frequencies in the range of 8.80~24.86 Hz and vibration modes that are integrated uniform deformations, while the 6th to 20th stages are of a high-order local dense mode with natural frequencies in the range of 25.96~36.14 Hz and local deformations that are significantly larger than the integrated deformations;the structural displacement induced by high-frequency vibration modals is very small, but the internal force response of local elements are much larger than the displacement since the modal amplitude vector of the internal force calculation is multiplied by the square of the modal frequency; the structure dynamic damage induced by the tunnel blasting vibration is mainly controlled by the instantaneous high stress rather than the displacement; and under intense vibrations, tensile stresses are high at the brick doors, window corners, contact areas of brick and concrete elements with a stress concentration, parapet wall, side-walls, partition walls and balconies and this is where damage often occurs. 2017 Vol. 54 (3): 135-141 [Abstract] ( 1202 ) [HTML 1KB] [ PDF 0KB] ( 474 ) 142 Establishment and Optimization of a Driving Speed Model for Shield Tunnelling in Mixed Ground In the process of shield tunnelling, the driving parameters should be selected appropriately according to the geological conditions. The correct choice of driving parameters can effectively improve excavation efficiency, reduce tool wear and maintain excavation face stability. In this paper, orthogonal tests of driving parameters are carried out based on the construction practice of a metro running tunnel section. Through collection and analysis of shield driving parameters, a parametric model of shield driving speed is established. The model parameters are optimized using the fastest driving speed as the goal function with the result of obtaining the optimal driving parameters of the shield construction in mixed ground. The research results provide a theoretical basis for setting shield tunnelling parameters under the same ground conditions, and provide a reference for shield construction in other strata. 2017 Vol. 54 (3): 142-147 [Abstract] ( 1116 ) [HTML 1KB] [ PDF 0KB] ( 502 ) 148 Efficiency of Rock Breaking by TBM Cutters in a Joint Rock Mass with Different Confining Pressures In order to improve TBM tunnelling efficiency and reduce construction costs, it is necessary to study the efficiency of rock breaking in a joint rock mass. UDEC was adopted to perform research on the influence of joint spacing, joint inclination, cutter spacing and penetration on rock breaking efficiency. The results show that: 1) the trend of specific energy consumption decreasing with increasing confining pressure slows down when the joint inclination increases or decreases from 30° to 90° or from 30° to 0° , and the increase of confining pressure is adverse to rock breaking when the joint inclination is approaching 90° or 0°; 2) The smaller the joint spacing, the more obvious the influence of confining pressure on specific energy consumption. With an increase of joint spacing, the influence of confining pressure on specific energy consumption decreases until it has no effect; 3) When the joint inclination is around 0° , it is better to choose a small cutter spacing as long as it meets the requirements of installation; when the joint angle is around 30° , the specific energy consumption is the lowest if the cutter spacing is about 100 mm; when the joint inclination is around 60° , the specific energy consumption is the lowest if the cutter spacing is about 120mm; and 4) If cracks produced by two cutters are cutting through the joint rock mass, the rock breaking efficiency is best with small rock mass penetration. 2017 Vol. 54 (3): 148-154 [Abstract] ( 1073 ) [HTML 1KB] [ PDF 0KB] ( 467 ) 155 A Prediction Model for Cutter Wearing Based on Driving Parameters Based on construction of the Shiziyang shield tunnel in mixed ground and the two main geological condi? tions of mixed ground mainly consisting of soft rock and hard rock, influence of four parameters on cutter wearing was studied: shield total thrust, cutterhead torque, tunnelling advance rate and cutter head rotation speed. The reasons for cutter wear were analyzed and an expression for the relationship between cutter wear degree and the four driving parameters was established, providing a theoretical basis for cutter wear reduction and a prediction for the longest driving distance of a shield under similar geological conditions. 2017 Vol. 54 (3): 155-161 [Abstract] ( 1160 ) [HTML 1KB] [ PDF 0KB] ( 460 ) 162 Testing and Analysis of Mooring Force and Motion Response during Immersion of Tunnel Elements In the process of mooring and sinking tunnel elements, the mooring force and motion response of the tun? nel elements are two key parameters that govern construction quality, and even the safety of the immersed tunnel. After calculations, processing, calibration, and waterproofing treatment, a new type of mooring force sensor was designed and made to solve the difficulties in monitoring construction of the Zhoutouzui immersed tunnel project in Guangzhou. These difficulties included a large load, deep water resistance and installation difficulty. Based on the construction technology of immersed tunnel elements, the tests of the mooring force and attitude of elements were carried out, the current resistance coefficient of the tunnel element (a floating structure with a large block coefficient) was analyzed, and then the field test results and numerical analysis results were compared. The study results show that the sensors can be made and installed conveniently while meeting the requirements of monitoring; the coefficent of lateral flow resistance should be 2.05 for immersed element; and the calculation results agree well with the test data. 2017 Vol. 54 (3): 162-168 [Abstract] ( 1165 ) [HTML 1KB] [ PDF 0KB] ( 466 ) 169 Discussion of Construction Techniques for the Slurry Shield-Driven River Crossing Tunnel with Large-Section With the rapid development of urban traffic, there are increasing needs for short and large-section traffic tunnels in the Yangtze River delta area with many rivers in China. To meet the slope requirements, the depth of overburden under river is usually small, and the pressure at tunnel face is difficult to be controlled when tunnel crosses under the river revetment where the overburden varies largely, which increases the risks and difficulties of construction and becomes a key issue concerning project safety. Based on the Chengjiangxilu tunnel in Jiangyin, construction risks were analyzed in respects of small overburden and the river revetment; in order to reduce construction risks of the large-diameter slurry shield tunnel crossing river, some construction techniques were proposed for rein? forcement of river revetment and riverbed of Zhaqiao River; and appropriate construction parameters were selected and construction control measures were adopted in the process of shield construction. 2017 Vol. 54 (3): 169-173 [Abstract] ( 1079 ) [HTML 1KB] [ PDF 0KB] ( 447 ) 174 Deformation Control Techniques for the Yanmenguan Tunnel in Squeezing Surrounding Rocks The section of soft surrounding rock around the Yanmenguan tunnel, which exhibits a straight align? ment, has large overburdens and tectonic stresses, which is extremely challenging for deformation control during tunnel construction. Considering the characteristics of the squeezing surrounding rock around the Yanmenguan tunnel,a study was conducted with respect to measures for excavation deformation control. The Finite Differential Method (FLAC3D) was used to determine the rational length of the reserved core soil of the arced pilot tunnel during threebench seven- step construction, and the length of the system anchor bolt was optimized based on the scope and shape of the plastic zone of the tunnel surrounding rock. Furthermore, a study on the mechanical effect of the double-layer support and the construction time of the inner support was carried out: it concludes that it is best for construction of the inner support to take place at the same time as that of the inverted arch of the outer support. Comprehensive deformation control techniques, which include a 3~4 m long core soil, advanced support, an optimized system anchor bolt, a feet-locked anchor bolt and double-layer support (H175+I22a), are proposed based on numerical simulation and engineering practice that consider the squeezing surrounding rock around the Yanmenguan tunnel. 2017 Vol. 54 (3): 174-180 [Abstract] ( 1109 ) [HTML 1KB] [ PDF 0KB] ( 418 ) 181 Support Deformation Induced Clearance Invasion and Treatment for a Pelitic Soft-Rock Tunnel Passing through a Water-Rich Fault Zone Serious initial support deformation occurred when the exit of the Beilingshan tunnel on the NanningGuangzhou railway passed through a water-rich fault zone in pelitic soft rock, and a series of countermeasures were adopted at the site, but they failed. Regarding this situation, the whole evolution of the initial support induced clearance invasion and the macroscopic characteristics of tunnel were analyzed, then further analysis and research was carried out regarding the reasons and mechanism of clearance invasion for tunnels passing through water-rich fault zones in terms of unfavorable geology, the coupling cycle of underground water and mudstone, tunnel structure, original design and construction scheme based on the actual measured data. Comprehensive schemes for the inside tunnel and outside tunnel were proposed. By way of numerical simulation, a calculation regarding arch replacement was carried out and the relative optimum parameters were obtained. With this treatment scheme, the exit end of the tunnel successfully passed through the water-rich fault zone, which provides a theoretical and practical references for similar tunnels regarding initial support deformation induced clearance invasion. 2017 Vol. 54 (3): 181-189 [Abstract] ( 1169 ) [HTML 1KB] [ PDF 0KB] ( 444 ) 190 Construction Techniques for a Shallow-Buried Tunnel with a Large Section in Hard Rock Based on the construction of the right line of the large-section subsea tunnel at Jiaozhou Bay, a discus? sion was carried out regarding the construction method for the shallow-buried large-section bored tunnel. Based on a study of the recommended designed construction scheme and considering the construction experience and advanced construction concepts both at home and abroad, the safe, rapid and economically successful large-section excavation was made possible by advanced grouting, long anchor bolts, reinforcement of the longitudinal connection and weak blasting, and the technical and organization difficulties were solved in respect to the construction of the shallow-buried bored tunnel with a large-section in hard rock. 2017 Vol. 54 (3): 190-194 [Abstract] ( 1151 ) [HTML 1KB] [ PDF 0KB] ( 453 ) 195 Key Techniques for an Urban Underpass in Saturated Soft Soils Constructed by the Shallow Mining Method ZOU Jinjie ZHANG Lifeng HU Xianguo PENG Jiaqiang GU Xingjie Taking an underpass project in Hangzhou as an example, this paper introduces some key techniques for an urban underpass in saturated soft soil constructed by the shallow mining method. For the pre- reinforcement ahead of the tunnel face, the TSS method is characterized by controllable grouting pressure, uniform grout distribution and the reinforcement effect of grouting pipes. For the excavation method, the CRD method with six excavation portions should be adopted for the first excavation of the middle part and then for excavation of the two side parts,but the length of the reserved core soil must be determined considering the effects of the pre-grouting reinforcement and the controlling effects of the foot-locking anchor against side wall deformation. For reducing the risk of removing the temporary support, the longitudinal connection reinforcements should be enhanced and small pipes should be installed in full-face to improve structure rigidity and soil strength, as well as to control ground settlement. 2017 Vol. 54 (3): 195-199 [Abstract] ( 1109 ) [HTML 1KB] [ PDF 0KB] ( 451 ) 200 Water Pressure Monitoring Method for the Segment Structure of a Deep-Water Shield Tunnel DUAN Fenghu1,2 The water pressure load outside of a deep-water shield tunnel plays an important role in the security of the segment structure. Problems exist as a result of a large overburden and high water pressure outside of the tunnel:high installation risk for and a low survival rate of the osmometer, as well as less reliability regarding the data obtained. In this paper, a device and installation method are designed for the osmometer used outside the segment structure of the deep-water shield tunnel, and they are applied to monitor the water pressure outside a submarine shield tunnel in Zhanjiang, with satisfactory results obtained 2017 Vol. 54 (3): 200-203 [Abstract] ( 1089 ) [HTML 1KB] [ PDF 0KB] ( 439 ) 204 Malfunction Analysis and Improvement of the Hydraulic Thrust System of the Shield Machine Hydraulic thrust system is critical for the shield machine. Based on a practical case, the reason to cause malfunction of certain type of shield machine was analyzed, and the optimization and improvement of the thrust system were carried out in light of the main problems and construction condition, which made it less difficult for the iterant inspection and maintenance, improved equipment performance, and reduced the cost and complexity of controlling. 2017 Vol. 54 (3): 204-206 [Abstract] ( 1055 ) [HTML 1KB] [ PDF 0KB] ( 473 )

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