[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   2017 Vol.54 Issue.4 Published 2017-08-25 Article 1 Quality and Technical Countermeasures in Highway Tunnel Engineering Issues related to the engineering quality of highway tunnels are introduced, and the causes of geological hazards are analyzed using collapse, rock burst, water inflow, mud burst, karst, slide, and gas as examples, and technical countermeasures are proposed. The cases concerning portal quality of tunnels adopting the“advanced portal construction method”and a“special-shaped shed-tunnel structure with large span”are presented. The measures to guarantee highway tunnel quality and development trends are described in terms of mechanization, assemblage and informatization. 2017 Vol. 54 (4): 1-12 [Abstract] ( 1308 ) [HTML 1KB] [ PDF 7179KB] ( 2282 ) 13 Review of BIM and Its Application in Underground Engineering WANG Jianxiu1,2 YIN Yao2 HU Lisheng 3 Starting with the initial development and technical significance of the building information model (BIM), the present situation regarding the application, technical standards and extended application of BIM are summarized in this paper. Based on typical cases of domestic and overseas BIM application in underground engineering construction, the advantages and disadvantages are discussed, and the significance of digital underground space and engineering studies is put forward regarding the development of BIM. The status quo of BIM, its standard setting, software development, technical personnel training and application in underground space engineering are analyzed and examined. 2017 Vol. 54 (4): 13-24 [Abstract] ( 1916 ) [HTML 1KB] [ PDF 2194KB] ( 4362 ) 25 On Research Status of Surface Settlement of a Bored Subway Tunnel with a Shallow Overburden DUAN Baofu SONG Likun ZHOU Xinming ZHOU Yuancheng Subway construction often encounters poor geological conditions, numerous interfering factors and com? plex environment. Surface settlement is a main problem related to the safety of bored tunnels with shallow overburdens. With the developing theory and technology of subway construction, further study on surface settlement control has been conducted regarding the prediction and management of surface settlement. Good research results have been achieved using empirical formulas, theoretical analysis, model tests and numerical simulation. In light of the current situation of surface settlement control, the deformation prediction, construction method, monitoring and information feedback were analyzed, and the direction for future development was proposed. Guide:null 2017 Vol. 54 (4): 25-32 [Abstract] ( 1178 ) [HTML 1KB] [ PDF 938KB] ( 2492 ) 33 Development of Defect Evaluation Techniques for Highway Tunnel Lining Thickness and Compactness In light of the current inspection situation regarding the thickness and compactness of highway tunnel linings, the applicability and feasibility of various kinds of inspection methods are analyzed, and the basis of judgment for inspection results is determined. Such aspects as work platform improvement, measurement line layout and recording, constant dielectric calibration of the lining, inspection process records, result analysis, test reports and task implementation, which are involved in inspections by the geological radar method, are described. Some beneficial suggestions for future work are proposed. Guide:null 2017 Vol. 54 (4): 33-40 [Abstract] ( 1213 ) [HTML 1KB] [ PDF 1359KB] ( 2952 ) 41 Risk Evaluation System for the Impacts of a Concealed Karst Cave on Tunnel Construction XUE Yadong1,2 LI Shuobiao3 DING Wenqiang1,2 FANG Chao4 Concealed karst caves, a major hidden danger in the construction of tunnels in karst regions, are in? clined to cause serious accidents such as water bursts and mud gushing, collapse and subsidence. Few systematic studies have been carried out concerning karst cave related risk identification and warning theories. Based on case statistics and theoretical analysis, geotechnical and construction risk factors were selected for studied. The geotechnical factors include the orientation of a karst cave relative to a tunnel, the type and filling condition of the karst cave, the interval between the cave and the tunnel, the grades of the surrounding rocks and the karst cave scale. The construction factors include advanced geological forecast and construction monitoring. Considering the relationship between risk factors and construction accidents regarding karst tunnels, the constant weights of various risk factors were calculated using the Analytical Hierarchy Process (AHP). In light of different karst tunnels, the weights of risk factors were calculated by variable weight theory based on constant weight. Considering the evolution rules of karst tunnel safety accidents, the valuing scope of risk factors was determined, and grading standards for the risk evaluation of concealed karst caves were presented. The feasibility and rationality of the evaluation system were verified through practical cases. 2017 Vol. 54 (4): 41-47 [Abstract] ( 1207 ) [HTML 1KB] [ PDF 1177KB] ( 2256 ) 48 Analysis of the Reliability of Advanced Geological Prediction during TunnelConstruction Based on the Attribute Recognition Theory Advanced geological prediction is an important technical measure that foresees unfavorable geological conditions in front of the working face and reduces the risk associated with construction. In order to ensure the accuracy and reliability of predicted geological information, an assessment model based on attribute recognition theory is developed for assessing the reliability of advanced geological prediction in tunnels. Considering the influential factors for prediction reliability, and with respect to the scheme, technician, equipment, environment and management,etc., the number of prediction methods, the career time of technicians, the maintenance frequency of the equipment,the number of people and equipment that have nothing to do with prediction, and the rationality of prediction management is selected as the assessment index, a qualitative and quantitative analysis of the indexes are conducted,and the classification criteria for the indexes is determined. The index weight is calculated by integrating a simple correlation function. The assessment indexes acquired by site investigation and the attribute measure function are used to calculate a single index attribute measure and comprehensive attribute measure of the predicted tunnel section, and the reliability of the advanced geological prediction results is assessed by the confidence criterion. The practical case shows the attribute assessment results are consistent with the actual situation. 2017 Vol. 54 (4): 48-55 [Abstract] ( 1110 ) [HTML 1KB] [ PDF 1216KB] ( 2166 ) 56 Calculation Method for Loosening Earth Pressure of a Shallow-Buried Tunnel Considering the Soil Arch Effect With an increase of crown displacement of a shallow-buried tunnel, the soil arch structure experiences four stages: the upper concave arch, the triangular arch, the lower concave arch and the rectangular arch. For shal?low-buried tunnel construction, the soil arch structure is mainly composed of a lower concave and rectangular arch,and the soil arch effect varies constantly with the variation of the arch structure. Criteria for judging the arch structure is established assuming the tunnel arch structure is a lower concave arch. The theoretical side displacement δ1′is obtained based on crown displacement δ. When the displacements δ1 at the two sides during tunnel construction are larger than the theoretical side displacement δ1′ of the lower concave arch, the arch structure develops as a rectangular arch, otherwise it develops as a lower concave arch. Based on an analysis of the laminar differential chromatographic method, a calculation formula for the loosening soil pressure of shallow-buried tunnels is presented. Ex? ample calculations show the loosening earth pressure of a shallow-buried tunnel has a direct relationship with the soil arch structure, and the loosening earth pressure will decrease substantially when the soil mass develops as a rectangular arch from a lower concave arch, which means the influence of the soil arch effect increases. Guide:null 2017 Vol. 54 (4): 56-62 [Abstract] ( 1212 ) [HTML 1KB] [ PDF 1806KB] ( 1585 ) 63 Soil Pressure of the Surrounding Rock for a Subway Tunnel across Ground Fissures under a Train Load Based on the similarity theory, a model for the dynamic interaction between the stratum and a subway tunnel across ground fissures was designed. Based on an analysis of the model test results, the soil pressure of the surrounding rock and the contact pressure between the rock mass and tunnel lining structure under the train load were systematically studied with respect to a horseshoe-shaped subway tunnel across ground fissures in different ways. After analyzing the relevant test data, the following conclusions were determined: 1) if no settlement occurs at the hanging side rock of the ground fissure, there is not a big difference between the soil pressure of the rock mass of a multi-section tunnel and that of an integral tunnel, otherwise there is a big difference between them; 2) as for a multi-section tunnel, the additional soil pressure with ground fissures is larger than that without any ground fis? sures; and 3) as for the two kinds of tunnels, the distribution and magnitude of the contact pressure produced under the action of ground fissures are very close, but the soil pressure in column Y1 of the hanging side decreases largely due to voids caused by ground fissure action compared with the soil pressure in column Y2 at the heading side. 2017 Vol. 54 (4): 63-67 [Abstract] ( 1153 ) [HTML 1KB] [ PDF 2629KB] ( 2247 ) 68 Surrounding Rock Stress in the Failure Process of a Tunnel Buried in an Inclined Soft/Hard Interbed Stratum Based on the Yajiang tunnel on the Nanchuan-Fuling expressway in Chongqing, a model test for the fail? ure process of a tunnel buried in an inclined soft/hard interbed stratum was performed. The results indicate the tunnel′s failure begins from the soft stratum around the left sidewall. The failure process can be divided into five stages according to the failure characteristics, and the surrounding rock′s failure leads to the unloading effect of the surrounding rock stress. A numerical model of the Yajiang tunnel was also established by finite element software, and the numerical calculation results show that the extreme value of the surrounding rock′s maximum principal stress always occurs at the left haunch, which is different from where failure first happens. According to the stress distribution along the vault route, the third principal stress is the highest one. The surrounding rock stress varies in a shock? ing way as a result of different stratum properties caused by the soft/hard interbed stratum. At the first stage of the failure process, the scope of the pressure arch is about 1.35 times the tunnel′s excavated span. 2017 Vol. 54 (4): 68-76 [Abstract] ( 1042 ) [HTML 1KB] [ PDF 4003KB] ( 2113 ) 77 Study on the Vault Load Calculation Method for Urban Metro Tunnels in Inhomogeneous Strata CHAO Feng1,2 LIU Dagang3,4 YANG Xiaorong5 LI Lei6 HUANG Haibin3,4 Due to the fluctuation of strata boundaries and a wide variation of parameters for strata passed through by a shield tunnel, the accuracy of load calculations is affected by the selection of calculation parameters. Based on Terzaghi′s soil relaxation pressure formula, the vault load calculation method for a shield tunnel in fluctuating strata was studied. Correction methods for vault load calculations were determined by considering the conditions of horizontal and tilted strata. Regarding the boundary in a horizontal stratum, a method for sliding surface width value selection is given by analyzing the proportion of the upper strata in a tunnel section. Regarding the boundary in a tilted stratum, the sliding surface widths of the left and right sides of the shield tunnel were analyzed and value selection is given based on the experience with the horizontal stratum. A field test of the lateral earth pressure was conducted aiming at a shield tunnel with a diameter of 6 m in fluctuated strata, and the results are compared with those obtained by the classical theoretical formula; the two sets of results agree very well. 2017 Vol. 54 (4): 77-82 [Abstract] ( 1463 ) [HTML 1KB] [ PDF 1632KB] ( 2862 ) 83 Application and Comparison of Conventional and Generalized Response Displacement Methods for Shallow-Buried DOT Shield Tunnels YAN Qixiang YAO Chaofan HE Chuan GENG Ping The basic principles, analytical method and problems regarding the conventional response displacement method are described. The formulas of formation spring stiffness are given with the assumption of both a slip and noslip contact surface, and a generalized response displacement method is put forward based on the formation-structure model. As for this method, the seismic force displacement is applied on the boundary at the left and right side,which are restricted by horizontal sliding support, and the boundary of the underlying bedrock is restricted by a fixed support. The frictional contact unit is introduced between the boundaries of the formation interface to imitate the slipping effect of the interface. Under different interfaces, a comparison between the conventional response displacement method and the generalized response displacement method for shallow-buried DOT shield tunnels shows that: 1) the generalized response displacement method with the assumption of interface slippage can reflect the seis? mic effects of the DOT shield tunnel more accurately; 2) under the seismic force displacement, the additional bending moment of the segment lining distributes in an inclined number 8, and the additional bending moment of the center pillar is linear with the inflection point near the midpoint; 3) the additional axial force on the segment is basically pressure, and the additional axial force on the center pillar is one of tension with an unchanged value along the height; and 4) the additional shear force on the segment distributes as a number 8 and the additional shear force on the center pillar remains unchanged along the height. Guide:null 2017 Vol. 54 (4): 83-90 [Abstract] ( 1173 ) [HTML 1KB] [ PDF 2945KB] ( 2438 ) 91 Sensitivity Analysis of the Effect of Depth and Slope Gradient on the Surrounding Rock Stability for Shallow-Buried Tunnels WANG Hui1,2 The sensitivity analysis of the effects of buried depth and slope gradient on surrounding rock stability is very important for alignment selection and the determination of a construction scheme for a shallow-buried tunnel.The deformation rules of surrounding rock under different bias angles and buried depths have been analyzed in previous work, and based on this, a sensitivity analysis is proposed to study the sensitivity of the effects of tunnel overburden and slope gradient on the stability of surrounding rock (surface settlement, vault settlement and plastic zone distribution). The results show the surface settlement and vault settlement are relatively sensitive to tunnel overburden but not so sensitive to the bias angle; as for the plastic zone area, it is more sensitive to the bias angle than the buried depth of tunnel. Guide:null 2017 Vol. 54 (4): 91-96 [Abstract] ( 1036 ) [HTML 1KB] [ PDF 5387KB] ( 2110 ) 97 Prediction and Analysis of Ground Displacement and Stress Caused by the Excavation of a Shallow-Buried Shield Tunnel in a Compound Stratum FU Helin1,2 ZHANG Jiabing1,2 HUANG Zhen1,2 SHI Yue1,2 WANG Jing1,2 XING Xuesheng1,2 To reveal the distribution of ground displacement and stress caused by the excavation of a shallow-bur? ied shield tunnel in a compound stratum, the Покровский equivalent layer method was applied to simplify the problem into a solution for the displacement and stress distribution in a homogeneous formation. Using the modified Loganathan′s formula, the expressions of ground displacement and strain component and stress component were deduced, and a displacement field distribution prediction model was established. Based on a theoretical prediction model, the predicted and measured values were compared, and the effects of elasticity modulus ratio n of the upper and lower soil layers, the depth of tunnel z and the Poisson ratio μ on tunnel excavation are also discussed. As for a tunnel excavation in a soft interbed stratum, the equivalent thickness K of the soft interbed stratum is introduced.The research results show that: 1) with an increase of the n value, the maximum surface settlement Smax, maximum additional horizontal stress σx and vertical stress σz decrease; 2) with an increase of the z value, the maximum settle? ment increases; 3) with an increase of the μ value, the Smax value decreases and the maximum additional horizontal stress and vertical stress increase; 4) with an increase of the K value, the Smax value increases; and 5) during tunnel construction, displacement and stress diffusion occur in the stratum that is hard at the upper part and soft at the lower part, while displacement and stress concentration occur in the stratum that is soft at the upper part and hard at the lower part. 2017 Vol. 54 (4): 97-106 [Abstract] ( 1119 ) [HTML 1KB] [ PDF 4585KB] ( 2097 ) 107 Effects of Soft Soil Creep on the Load and Deformation of a Tunnel Lining LIU Mengbo1 LIAO Shaoming1 ZHU Mingyong2 YANG Junlong3 MEN Yanqing The creep property of soft soil can weaken the soil-arch effect, leading to the variation of the load and deformation of the tunnel lining with time. Considering the viscosity of soft soil, a creep model coupling with time hardening rule and the Druker-Prager yield criterion was adopted, and a finite-element model was established using numerical analysis software ABAQUS to analyze the effect of soft soil creep on the contact pressure between the tunnel and stratum, tunnel deformation and internal force varying with time based on the data obtained from an indoor tri-axial rheological test of Shanghai soft soil. The influence of soft soil creep on the soil-arch effect and longterm mechanical properties of the lining is discussed in this paper. Guide:null 2017 Vol. 54 (4): 107-114 [Abstract] ( 1170 ) [HTML 1KB] [ PDF 3574KB] ( 2050 ) 115 Applicability of Pre-Lining Based on the Convergence-Confinement Method DU Linlin WANG Xiuying LIU Weining It is critical to control the pre-convergence of the advance core at the working face in order to control soft rock deformation. The lateral continuous pre-lining shell finished by the mechanical pre-cutting technique can protect the advance core soil and thus control pre-convergence. The interaction between the pre-lining support and the rock mass is complex due to the time-space effect at the tunnel face. Based on the convergence-confinement mechanism, the theoretical solution for the interaction between the pre-lining and the rock mass was derived, and the law of the applicable depth of the pre-lining varying with concrete strength, rock mass parameters and pre-lining parameters was studied. The results indicate: 1) the higher the compressive strength of the pre-lining concrete,the larger the applicable depth for pre-lining support, thus it is a linear relationship between the concrete compressive strength and the applicable depth; 2) with an increase of the stress release coefficient, the applicable depth of the pre-lining increases as under the same concrete compressive strength; 3) the pre-lining thickness has a significant effect on the applicable depth of the pre-lining, and the bigger the pre-lining thickness, the larger the applicable depth of the pre-lining; and 4) the applicable depth of the pre-lining increases if the tunnel diameter is reduced 2017 Vol. 54 (4): 115-122 [Abstract] ( 1085 ) [HTML 1KB] [ PDF 2295KB] ( 1951 ) 123 Measurement Technology for Strata Displacement at Different Depths Induced by Shield-Driven Tunnelling ZHANG Jinxun1 JIANG Hua2 JIANG Yusheng2 GE Zhenyi2 Based on a study of the measurement technology for strata displacement at different depths induced by shield tunnel excavation, a kind of high-precision displacement measurement technology was put forward and successfully used and validated in Beijing metro line 14. First, the technology integrates the static level system with a single-point displacement meter by platform anchorage, calculating the displacement measurement with high precision, high frequency and low disturbance. Secondly, using the cutterhead center as a zero point, a dynamic coordinate system was established under the assumption of stable tunnel excavation in homogeneous strata, and the coordi? nate transformation of displacements in different depths was proved to be feasible. Finally, the multiple regression analysis method was used to eliminate the influence of actual unstable construction parameters on the measurement results, guaranteeing the accuracy of the measurement data, guiding the control of settlement induced by shield tunnelling and design, and supporting construction and risk management of shield tunnels in complex conditions. Guide:null 2017 Vol. 54 (4): 123-130 [Abstract] ( 1076 ) [HTML 1KB] [ PDF 3153KB] ( 2103 ) 131 Strata Disturbance Influenced by Soil Mechanical Parameters Varying with Dynamic Tunnel Construction The relationship between the soil void ratio and the volumetric strain was derived based on a threephase system and the division of the disturbed areas due to tunnel construction, and volumetric strains of different disturbance areas were calculated by the finite-element method. Using the relationship between the soil mass mechanical parameter and void ratio as a reference, variations of mechanical parameters of disturbed soils before and after tunnel excavation were calculated, and the differences of influence on strata disturbance with or without considering the variation of soil mass mechanical parameters were studied. Compared with the calculation results under the assumption that the soil mechanical parameters are constant during tunnel excavation, the practical case analysis indicates the maximum ground settlement increases by 8.1% and the plastic area increases by 55.6% when considering the variation of soil mechanical parameters. 2017 Vol. 54 (4): 131-136 [Abstract] ( 1078 ) [HTML 1KB] [ PDF 1569KB] ( 2163 ) 137 Stochastic Prediction Method for Ground Settlements Considering Gaps behind the Lining and Grout Distribution Modes CHEN Liang1 ZHOU Zelin2 The three main factors affecting ground settlement in shield tunnelling are the gap behind the tunnel lin? ing, the distribution mode of the grout and the deformation of soil at the excavation face, all of which are closely related to soil conditions and construction technology. There is not adequate quantitative research on these factors.Based on the stochastic medium theory, and the three parameters of equivalent gap value Δ1 , the distribution angle α of equivalent gap and negative ground loss value Δ2 were introduced to represent the three factors above, and a formula was deducted to predict 3D ground settlement in shield tunnelling. A quantitative analysis of the ground settlement affected by the parameters of Δ1 and α was performed. Based on the measured settlement data, a back-analysis was conducted to obtain the 3D solutions for predicting settlement values. The values of ground settlement calculated by this method were compared with the on-site measured data and the values of ground settlement calculated by a modified Peck formula, which shows the method proposed in this paper can predict the values and distribution characteristics of ground settlement more accurately, therefore verifying the reasonableness and reliability of this method. 2017 Vol. 54 (4): 137-145 [Abstract] ( 1010 ) [HTML 1KB] [ PDF 2425KB] ( 1842 ) 146 Bayes Discriminative Model for Predicting Rockburst Grades Bayes discriminative analysis was adopted to predict rockburst grades, and based on 108 rockburst cas? es, a Bayes discriminative model was built with six basic indicators such as maximum tangential stress of the surrounding rock σθ, uniaxial compressive strength σc , uniaxial tension strength σt , stress coefficient σθ/σc , brittleness coefficient σc/σt and elastic energy indicator Wet. In light of the Bayes discriminative model, the concept of odds ratio was proposed and used in the analysis of relationships between rockburst indicators and rockburst grades,and the analysis of the sensitivity of rockburst grades to indicators, then the reasonableness of the Bayes discriminative model with different indicator combinations was evaluated. The results show that the Bayes discriminative model with the combination of indicators σθ/σc and Wet was the most reasonable with high prediction effects, and the obtained expression for rockburst grade probability can be a reference for predicting rockburst grades in underground engineering. Guide:null 2017 Vol. 54 (4): 146-151 [Abstract] ( 1095 ) [HTML 1KB] [ PDF 1107KB] ( 1761 ) 152 Numerical Simulation of Air Resistance Generated by a High-Speed Train Passing through a Tunnel with a Perforated Wall GUO An′ning LUO Lulin JIA Yongxing MEI Yuangui A tunnel with a perforated wall is a new type of high-speed railway tunnel structure, and the aerodynam? ics induced by the passing of a high-speed train through the tunnel will differ from those of traditional tunnel. In this paper, the effects of a perforated wall on the air resistance produced by a high-speed train passing through a tunnel was studied based on the one-dimensional unsteady compressible non-homentropic fluid flow model and the characteristics of the generalized Riemann variables method. The variation laws of the maximum and average values of the air resistance of tunnels of different lengths with or without perforated walls were simulated, and it was concluded that a tunnel with a perforated wall may significantly reduce air resistance and that tunnel length does not affect the amplitude of air resistance under a certain speed. The effects of hole spacing, hole size and the running speed of a train on air resistance was analyzed for a 2 000 m-long tunnel with a perforated wall. The relationship among the air resistance, compression wave and expansion wave produced by a train passing through a tunnel with a perforated wall are discussed, as well as the relationship between the maximum air resistance and train speed 2017 Vol. 54 (4): 152-159 [Abstract] ( 953 ) [HTML 1KB] [ PDF 3006KB] ( 2056 ) 160 Application of Twin-Tube Complementary Ventilation in Highway Tunnels XIA Fengyong1,2 SONG Shenyou1 XIE Yongli2 WANG Yaqiong2 In light of an unbalanced ventilation load between the left tube and right tube of 4~7 km-long tunnels, a new method named twin-tube complementary ventilation is presented. Two air exchange cross channels were set up between the left tunnel tube and right tunnel tube, and extra jet fans were installed in the downhill tunnel in order to transport the surplus fresh air to the uphill tunnel through one air exchange cross channel to attenuate the pollutant concentrations and make the polluted air in the uphill tunnel flow into the downhill tunnel through another air exchange cross channel and reduce the air velocity in the uphill tunnel, by which the air quality of the two tunnel tubes can meet the relative sanitary standard. The design theory and calculation formulas were derived in detail and were utilized to conduct the design of a ventilation system for a certain tunnel. With the complementary ventilation network, the configuration scale of the fans was calculated and the economic benefits were analyzed. The results in? dicate the complementary ventilation technology can not only meet the tunnel ventilation demand but also reduce the initial investment and operating costs for ventilation without any ventilation shafts. 2017 Vol. 54 (4): 160-166 [Abstract] ( 1037 ) [HTML 1KB] [ PDF 2223KB] ( 2057 ) 167 The Required Air Volume of an Extra-Long Tunnel at a Plateau Considering Altitude and Longitudinal Slope SUN Ying LIU Xiaoxia Altitude and longitudinal slope are two factors affecting ventilation design of an extra-long highway tun? nel in a plateau area. Based on provided field-measured data regarding the altitude coefficient, and using the Dalijia Mountain Tunnel in Qinghai Province as an example, the altitude coefficients given in the specifications were modified and the required air volume was recalculated. Considering the impact of the longitudinal slope on vehicle speed, the required air volume under the condition of controlled vehicle speed was determined reasonably, providing an important basis for the ventilation scheme. 2017 Vol. 54 (4): 167-172 [Abstract] ( 1016 ) [HTML 1KB] [ PDF 667KB] ( 1812 ) 173 Ventilation with a Parallel Adit in a Super-Long Expressway Tunnel with a Large Overburden LIU Yongsheng1, 2 HONG Kairong1 ZHUO Yue1 ZHANG Jinhua2 FU Lixin2 Considering the challenge of building a shaft in mountainous areas, an operation ventilation scheme via parallel adit was proposed for expressway tunnels based on a super-long tunnel project with a large overburden in Tianshan. A study of the design of a parallel ventilation adit instead of an inclined shaft was conducted by a large number of ventilation network calculations and the analysis of the orthoronal design of the total cost of the ventilation system to analyze the short-term and long-term ventilation mechanism and ventilation scheme of this tunnel.The results show that: 1) the order of factors affecting the total costs of the ventilation system is the length of the independent ventilation section, the ventilation volume, and the ventilation duct area; 2) the selected short-term and long-term ventilation scheme has solved the problem of operation ventilation in an expressway tunnel with a low traf? fic volume; and 3) as for tunnels with lengths of several kilometers, it is not advisable for the polluted air at the front section to be totally exhausted from the ventilation duct--it may be partly exhausted to the next main tunnel section to reduce energy consumption. 2017 Vol. 54 (4): 173-179 [Abstract] ( 1143 ) [HTML 1KB] [ PDF 2116KB] ( 2187 ) 180 Discussion of a Theoretical Formula for the Friction Resistance of a Pipe Wall in Quasi-Rectangular Pipe Jacking LIN Yuexiang1 PENG Limin1 WU Guihang2 YANG Weichao1 SHI Chenghua1 LEI Mingfeng1 The jacking force is composed of the head resistance and friction resistance of the pipe wall, and the former is generally considered a constant value and the latter increases with an increase of jacking distance. The existing formula for calculating friction resistance of the pipe wall of a rectangular jacking pipe is analyzed, and it is found that the quasi-rectangle is simplified and the pressure arch effect is not considered under deep depth conditions in the existing theoretical formulas, which results in great differences between the calculation values and the measured values. The earth pillar theory and the M. M. Promojiyfakonov pressure arch theory are adopted to deduce a theoretical formula for calculating the friction resistance of the pipe wall of shallow-buried and deep-buried quasi-rectangular jacking pipes. Based on the case study, the friction resistance of the pipe wall calculated by the for? mula given in the specification is relatively conservative when the pipe-jacking tunnel is located in favorable stratum and has a large overburden with the forming of a pressure arch, while the results calculated by the formula proposed in this paper are more reasonable. 2017 Vol. 54 (4): 180-185 [Abstract] ( 1088 ) [HTML 1KB] [ PDF 1168KB] ( 2104 ) 186 Experimental Study of the Vibration Absorption Mechanism of Staged Wedge-Cut Blasting Technology ZOU Xinkuan1,2 PAN Qiang2 WANG Wei1 ZHANG Jichun2 YUE Heng2,3 In order to solve the contradiction between blast-induced vibration absorption and construction efficien? cy of tunnels approaching existing buildings by the drill and blast method, an optimized vibration absorption blasting technique named staged wedge-cut millisecond delayed blasting technology is developed, which is appropriate for tunnels in medium or soft rock masses. Specifically, it makes use of segmented alternative charging structures and millisecond delayed blasting technology to guarantee the formation of a cut cavity in a hierarchical way from the outside in and achieves the goals of effective vibration absorption and a good advance rate. Based on a detailed analysis of the mechanism of rock breaking and vibration absorption during staged cut blasting and theories of millisecond blasting and stress wave propagation, the determination method for the key parameters affecting vibration ab? sorption and cut effect is proposed (such as the cut depth ratio, the distribution ratio of segmented charging, the dip angle of the cut hole and the delayed time for each segment) and applied to the parameter design for the tunnel blasting test at the site. The site blasting test indicates the new staged wedge-cut blasting technique can effectively reduce the blasting-induced vibration by more than 30%, guarantee construction speed, and obtain a good advance rate and effect compared with the conventional cut blasting method. Guide:null 2017 Vol. 54 (4): 186-192 [Abstract] ( 1047 ) [HTML 1KB] [ PDF 2147KB] ( 2374 ) 193 Analysis of Measured Surface Settlements Induced by Bored Overlapping Tunnels TAI Qimin The Beihaibei-Nanluoguxiang running tunnel on Beijing Subway Line 6, which goes from running paral? lel on top and bottom to running parallel on the left and right and is excavated from the right tube (down line) to the left tube (up line), is the first bored overlapping tunnel in the Beijing area. Based on an analysis of surface settlement data measured by 18 monitoring sections, the law of ground surface deformation induced by the bored overlapping tunnelling was obtained. The research results show that: 1) with an increased angle and distance of the tunnel tubes, the overlapping effect of the strata settlement increases obviously and the influence of the later-built right tube on surface settlement increases gradually; 2) excavation of the left tube changes the form of the surface settlement trough, makes the maximum surface settlement deviate from the right tube and widens the settlement trough; 3) the existing structure obstructs deformation transmission and reduces surface deformation, which is more obvious for the double-tube tunnel compared with the single-tube tunnel; and 4) deep-hole grouting can effectively control surface settlement and reduce the influence of construction on the surrounding environment. 2017 Vol. 54 (4): 193-200 [Abstract] ( 1055 ) [HTML 1KB] [ PDF 4455KB] ( 1400 ) 201 Shield Construction Techniques for Pile Foundation Cutting and Foundation Underpinning CHEN Jufei LIU Houqi YOU Qiaoxian Based on the running tunnel from the Ludan village station to the South People Road Station to the Xiangxi Village Station of Shenzhen Metro Line 9, the construction techniques for a shield cutting through a pile foundation in two different cases are described. The parameters of total thrust, advance rate, cutterhead torque, earth pressure, etc., were controlled during construction, which achieved smooth cutting and the successful passing of the pile foundation, controlled the settlement of the surface and an adjacent building, reduced construction costs and impacts on the surrounding environment and shortened the construction period. Guide:null 2017 Vol. 54 (4): 201-206 [Abstract] ( 1084 ) [HTML 1KB] [ PDF 3066KB] ( 2144 ) 207 Application of a Comprehensive Geological Prediction System to Construction of the New Tongluoshan Tunnel ZHOU Jie XI Jinzhou The Tongluoshan tunnel on the Nanchong-Chongqing motorway passes through a coal seam, goaf and gi? ant fault zones with complicated geological conditions. It will very likely encounter the geological hazards of coal and gas outbursts and water inflow during construction. Considering that conventional prediction methods have their applicable conditions and advantages and disadvantages, it is difficult to make an accurate judgment of geological conditions by any single method, and so a comprehensive geological prediction system that combines tunnel reflection tomography (TRT), transient electromagnetic method (TEM) and ground penetrating radar (GPR) was implemented during construction of the Tongluoshan tunnel. The conditions of surrounding rock and underground water ahead of the working face were obtained based on mutual multi-parameter corroboration. This method provides safe and timely early warnings for tunnel construction and reliable technical supports for the determination and alteration of the construction scheme. Guide:null 2017 Vol. 54 (4): 207-212 [Abstract] ( 1080 ) [HTML 1KB] [ PDF 3105KB] ( 2207 ) 213 Study and Development of a Linear Drilling-Type Pre-Cutting Machine for Tunnels in Soft Rock YANG Jikai1 WANG Xiuying The mechanical pre- cutting method is a predominant method for tunnels in soft rock, by which the formed pre-lining can effectively control stress release and stress redistribution, significantly reduce the height of the load-carrying arch and thus control deformation of the rock mass. However, pre-cutting technology has some difficulties regarding completing troughs, water sealing and mass equipment handling. A new thought for the development of a pre-cutting machine is proposed based on the above and the first generation of a linear drilling-type precutting machine is developed. Trough cutting and concrete pouring are carried out under the protection of a driving box, with little trough deformation and a uniform texture of the concrete arch shell. Industrial tests shows that this new type of machine can truly realize the original intention of pre-cutting technology and possesses unique advan? tages. 2017 Vol. 54 (4): 213-218 [Abstract] ( 1112 ) [HTML 1KB] [ PDF 3138KB] ( 1998 ) 219 Implementation and Application of Explosion Proofing and the Self-Diagnosis Function for Construction Machinery in Gas-Rich Tunnels LIU Rong1 YANG Chunhe1,2 JIANG Deyi1 GU Yilei1 Based on the anti-explosion standards and technical criterion for diesel vehicles, an intelligent explo? sion-proof device for construction machinery used in gas-rich tunnels was designed to address the problems with modification of construction machinery. The device forces the vehicle to flameout, turn off and lock when the tunnel gas concentration is at or above the allowed maximum concentration. To prevent gas explosions, the device begins to spray when the temperature of the exhaust system is at or above the allowed maximum temperature. Three shutting systems for equipment failure, abnormal water level and exceeding the maximum temperature were designed for the air exhaust system to improve device reliability. Practice indicates that the intelligent explosion- proof device is characterized by rapid installation, easy use and safe operation. Guide:null 2017 Vol. 54 (4): 219-224 [Abstract] ( 952 ) [HTML 1KB] [ PDF 1357KB] ( 2232 )

More>>   · · More>>

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