Luo J.,Beijing Jiaotong University |
Lei G.,Beijing Urban Engineering Design and Research Institute Co. |
Hua F.,Beijing Urban Engineering Design and Research Institute Co.
Modern Tunnelling Technology | Year: 2017
Proper evaluation and correct selection of the waterproofing and drainage types for metro tunnels is an effective way to reduce water leakage during tunnel operation. Regarding selection of waterproofing and drainage patterns, normally a single evaluation factor of water inflow is used for evaluation and analasis instead of comprehensive evaluation system. Based on previous studies of waterproofng and drainage of metro tunnels, an AHP-based judgement system for types of waterproofing and drainage is put forward, a mathematical evaluation model of the analytic hierarchy process is established, weights of the hierachy index affecting influential factors of waterproofing and drainage in metro tunnels are determined, and quantification of the types of waterproofing and drainage is achieved with established criteria and standards. Practical cases show that the fuzzy synthetic evaluation method is consistant with the actual situation. Further study and verification are required for this application using a concrete project. © 2017, Editorial Office of "Modern Tunnelling Technology". All right reserved.
Rong B.,Tsinghua University |
Rong B.,Beijing Urban Engineering Design and Research Institute Co. |
Zhang G.,Tsinghua University |
Zhang J.-M.,Tsinghua University
Yantu Lixue/Rock and Soil Mechanics | Year: 2012
Pile groups are widely used in offshore wind power generation as its foundation. The bearing capacity and deformation of foundation, with strict requirements for the wind power generations, is of great significance to be investigated under horizontal loads that is the control factor of the fans tower. Centrifuge model tests for offshore pile foundation and typical clay ground are conducted to actively study the pile behavior and the deformation characteristics of the surrounding soil. The test results show that: under horizontal loads, the displacement of pile top increases with the increasing load, while the increasing rate speeds up after the critical horizontal load. The bending moment of pile has a maximum in the 1/5 of burying depth and a minimum in the 3/5 of it, while there is a certain value at the bottom of the pile. The deformation of the soil around the pile, which is divided into active region and passive region, decreases as the distance from the pile increases, while the influence area expands with the increasing horizontal load, and finally stabilizes at twice the pile diameter range.
Wang G.-B.,Hubei Engineering University |
Chen L.,Beijing Urban Engineering Design and Research Institute Co. |
Xu H.-Q.,Wuhan Metro Group Co. |
Li P.,Wuhan University of Technology
Yantu Lixue/Rock and Soil Mechanics | Year: 2012
More and more shield tunnels will crossing each other with very short distance with the rapid development of urban rail transit construction in China. There are four tunnels crossing each other between Hongshan Square Station and Zhongnan Road Station, which are the second line and the fourth line of Wuhan rail transit. The complicated multi-tunnels were simplified as four parallel tunnels and four perpendicular tunnels with different distances according to their practical characters. Three dimensional calculation models are established and their seismic responses are analyzed, in which the following aspects are considered: amplitudes seismic waves, tunnel net distance, tunnel space position, the difference of segment stiffness and the reinforced layer between tunnels. And then, their seismic capabilities are evaluated through two aspects: structure deformation and component internal forces. The analytical results show, (1) The net distances between tunnels have little influence on tunnel seismic responses; (2) The seismic capabilities of four perpendicular tunnels is superior to that of four parallel tunnels. (3) Adjacent overlapping multi-tunnels have good seismic capabilities and can satisfy seismic requirement. The research results can provide preliminary design for relevant practical engineering in future.
Cheng X.-H.,Beijing Urban Engineering Design and Research Institute Co.
Tiedao Xuebao/Journal of the China Railway Society | Year: 2014
For shallow tunnels, classic theories of surrounding rock loosening pressures differ notably in calculated results and are deficient in setting of some assumptions. In this paper overcoming assumption deficiencies from the classic theories, the practical formula of loosening pressures was deduced, which provided a new theoretical foundation for the arching effect of tunnels. With the formula, changes of loosening pressures with the buried depth, cohesion and internal friction angle accorded with the general law. The formula presented the macimum point pressures along with changing of the buried depth, this characteristic being similar to the rock pillar theory (Bierbäumer's theory) and Xie Jiaxiu's formula. The formula was able to be applied in the case of ordinary soil tunnels of the internal friction angle φ≤45°, and when φ≤10°, the calculated result of the formula was slightly different from that of the Terzaghi's theory. Theoretical analysis on soil pillars and measured data indicate that the theoretical maximum value of loosening pressure should be the calculated value of the rock pillar theory. The calculated value of the presented formula and Terzaghi's theory are both smaller than the maximum value whereas the calculated value of the Xie Jiaxiu's formula is larger than the maximum value. Therefore, the proposed formula is an important reference to building of shallow earth tunnels and loose broken rock tunnels.
Hu S.-M.,Beijing Urban Engineering Design and Research Institute Co.
Tiedao Xuebao/Journal of the China Railway Society | Year: 2014
Taking the large-section loess tunnel project of the Lanzhou-Chongqing Railway as the background, the pressure-arch effect of loess surrounding rock was analyzed by model tests and finite element numerical calculations. The results show as follows: (1) Due to deflection of the load transfer path , the tangential stresses of the portion of the pressure arch ring bear radial loads and so increase; the closer to the tunnel boundary , the greater the increasing magnitude of the tangential stresses, and the pressure arch boundary develops to deep surrounding rock. (2) Keeping to the stress paths in side walls at the tunnel ring, the tangential stresses and radial stresses are lower than the original rock stresses, the tangential stresses show strong stress concentration and the radial stresses increase slightly. (3) Compared with clay soil, the shear strength of loess soil is relatively small, thus requiring a wider range of soil body to bear surrounding rock pressures and causing the outside boundary of the pressure arch to get far away from the tunnel section; referring to the loess surrounding rock pressure arches, the pressures are the largest at side walls and the smallest at arch bottoms and lie in between at arch tops. (4) The fracturing process of loess surrounding rock: undergoes four stages, i.e., generation of local fractures, expansion of local fractures, rapid through fracturing and retention of generation of residual strengths; vault loosening and collapsing occur upon side wall shear slide. (5) Numerical calculations and model tests yield the basically identical ranges of loess surrounding rock pressure arch, thus proving the existence of the pressure arch; the pressure arch bears its self weight as well as the external soil loads over the areas of loosening, pressure-arch and initial stressing from the tunnel ring to deep surrounding rock.
Yong-Chul K.,Dongyang Structure Engineering Co. |
Xue S.,Beijing University of Technology |
Zhuang P.,Beijing University of Civil Engineering and Architecture |
Zhao W.,Beijing Urban Engineering Design and Research Institute Co. |
Li C.,Beijing University of Technology
Earthquake Engineering and Engineering Vibration | Year: 2010
A theoretical model of a friction pendulum system (FPS) is introduced to examine its application for the seismic isolation of spatial lattice shell structures. An equation of motion of the lattice shell with FPS bearings is developed. Then, seismic isolation studies are performed for both double-layer and single-layer lattice shell structures under different seismic input and design parameters of the FPS. The influence of frictional coefficients and radius of the FPS on seismic performance are discussed. Based on the study, some suggestions for seismic isolation design of lattice shells with FPS bearings are given and conclusions are made which could be helpful in the application of FPS. © 2010 Institute of Engineering Mechanics, China Earthquake Administration and Springer Berlin Heidelberg.
Hu S.,Beijing Urban Engineering Design and Research Institute Co.
Tumu Gongcheng Xuebao/China Civil Engineering Journal | Year: 2013
For the loess tunnel in Lanzhou-Chongqing high-speed railway, the spatial deformation characteristics of surrounding rock is studied based on the loess engineering properties. The results show that: (1) The engineering properties of loess are characterized by its structure and well developed vertical joints, and structural loess may be modeled by the Mohr-Coulomb criterion with the bilinear failure envelope; (2) The well developed vertical joints may be caused by a large quantity of pore structure and small tensile strength; (3) The vertical displacement of the crown attenuates slowly, while the horizontal displacement of the side wall attenuates rapidly. The integrity of surrounding rock may be impaired due to the vertical joints, the deformation of surrounding rock caused by the excavation disturbance is gradually transferred to the deep; (4) In view of the engineering properties of loess, the plastic zone caused by excavation disturbance increases quickly and leads to tension damage in a wide range; (5) Compared to the existing theories, the computational model may fully consider the engineering properties. Due to the widespread vertical joints, the extrusion deformation at tunnel face induced by tunnel excavation is large, and hence the simulated results accord with the practical surrounding rock in loess.
Cheng X.,Beijing Urban Engineering Design and Research Institute Co.
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2014
A formula is derived to calculate the vertical earth pressure of circular tunnels in dense sand and hard clay grounds. The formula considers the coefficient of lateral pressure and the effect of oblique slip surface beside the circular tunnel on the basis of the hypothesis of Terzaghi theory. A method to calculate the lateral pressure coefficient is established in order to solve the proposed formula. A quantitative relationship between the vertical pressure and the factors such as the lining stiffness and the ground stiffness is also derived. The relationship shows that the decreasing of the lining thickness or the increasing of the elastic coefficient of resistance of ground lead to the increasing of the lateral pressure coefficient and the reducing of the vertical pressure. The results from the proposed method, the upper bound of limit analysis and previous experiment results are compared and found to be close to each other. The proposed method is simpler than the upper bound method and is suitable for both shallow circular and deep tunnels.
Li W.-H.,Beijing Jiaotong University |
Zhao C.-G.,Beijing Jiaotong University |
Du N.-X.,Beijing Urban Engineering Design and Research Institute Co.
Yantu Lixue/Rock and Soil Mechanics | Year: 2010
The statistical data of disasters caused by earthquake show that underground structures are more likely to be damaged when they in complicated geology and geological environment, such as nonuniform stratum, soft soil, soft interlayer nearby, etc. The seismic response of the metro station in the site with saturated soft interlayer is hereby analyzed. On the basis of the explicit finite element methods of dynamics analysis about single-phase and fluid saturated porous media, taking into account soft interlayer existing in the surrounding soil, a seismic response analysis method which can be used in metro station structure-saturated soil coupled system is established. By numerical modeling, the seismic responses of the key positions of metro station structure are shown under three actual earthquake recorders with different spectra characteristics which incident as the plane P wave. The factors, such as the location and thickness of the soft interlayer, are discussed in their influence on the dynamic response of metro station structure. The study results show that the soft interlayer has a very negative amplification on the dynamic response of metro station structure; and the amplification is the most unfavorable when the soft interlayer inside the metro station.
Hua F.-C.,Beijing Jiaotong University |
Hua F.-C.,Beijing Urban Engineering Design and Research Institute Co.
Yantu Lixue/Rock and Soil Mechanics | Year: 2013
Firstly, based on considering the theoretical solution of liner and grouting circle, the calculation and automatic drawing program has been developed with MATLAB software; and the relationships among water inflow, external water pressure and water head, tunnel radius, rock permeability, lining permeability are researched. Secondly, through the comparison of the numerical result and theoretical solution based on the FLAC3D, the correctness of application of numerical simulation methods to the tunnel seepage field are verified. On this basis, combined with the typical range of Qingdao metro, the seepage fields in the excavation stage and operation period are studied; and the relationships between water inflow and external water pressure of grouting circle are researched under different grouting circle thickness and grouting parameters. The results show that the application of grouting circle to the tunnel to reduce the water inflow is feasible; and the greater the grouting circle thickness and the smaller the grouting circle permeability, the less the tunnel water inflow; but the changing law of the external water pressure is on the contrary. The obtained results play an important role in designing the liner and the preliminary definition of the grouting thickness.