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大跨度深埋黄土隧洞的开挖效应研究 总被引：5，自引：0，他引：5
本文研究了大跨度深埋黄土隧洞在其它条件不变的前提下, 全断面开挖时黄土的变形破坏规律和衬砌中内力的分布规律, 指出了它们存在本质区别的原因在于不同的开挖方式, 揭示了开挖的本质, 分析了内力合理分布的条件。 相似文献
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The shape of an underground opening is a major factor influencing the stability of the underground excavation. Obtaining an optimized shape is significant in civil and mining engineering applications for increasing stability and reducing costs. This paper presents an updated method for finding the optimal shape of an underground excavation using the latest bi-directional evolutionary structural optimization (BESO) techniques considering material nonlinearities. Recent development in the BESO applications to underground excavation is discussed through illustrated examples. Details are given of the BESO method used to finding the optimal shape based on the global stiffness. The methodology of the stiffness based optimization techniques is described with examples of applications to underground excavation. Applications to underground void structures, such as cavern and tunnel, as well as underground solid structure such mine pillar are demonstrated. It is concluded that stiffness based optimization techniques are applicable to underground excavations and practical shape of an excavation can be generated as a result of the BESO application. 相似文献
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Modeling the Effects of Heterogeneity and Anisotropy on the Excavation Damaged/Disturbed Zone (EDZ) 总被引：2，自引：0，他引：2
S. H. Wang C. I. Lee P. G. Ranjith C. A. Tang 《Rock Mechanics and Rock Engineering》2009,42(2):229-258
Summary When modeling the mechanical behavior of underground excavations, it is necessary to include the influence of the rock mass
characteristics on the Excavation Damaged/Disturbed Zone (EDZ). In this paper, the Realistic Failure Process Analysis code,
RFPA, is used to model the extent of the EDZ. The inhomogeneous characteristics of rock at the mesoscopic level are included
by assuming that the material properties of the constituent elements conform to a Weibull distribution; the anisotropy is
incorporated as a transversely isotropic medium; the non-elastic characteristic is simulated via an elastic damage-based constitutive
law. A finite element program is adopted as the basic stress analysis tool. In this study, a notable feature is that no a
priori assumptions need to be made about where and how fracture and failure will occur – cracking can take place spontaneously
and can exhibit a variety of mechanisms when certain local stress conditions are met. The deformation and failure process
of anisotropic rock around excavations of different geometries is analyzed, and compared to experimental tests, showing similar
fracture patterns. Additionally, the effect of confining stress and of different material layers is modeled and discussed.
It is found that the model clearly illustrates that fracturing, both initiation and propagation, occurs as a combination of
the stress concentrations and weakness planes introduced via the transverse anisotropy – which could represent either foliations
or ubiquitous joint sets.
Correspondence: Dr. Shuhong Wang, Box 265, School of Resource and Civil Engineering, Northeastern University, Shenyang 110004,
P.R. China 相似文献
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Construction of a 16-m deep, 55-m wide, almost square, underground structure through 8-m of soft soils and 8-m of sandstone and siltstone led to the development of widespread settlements. The affected area extended to distances of over 200 m from the perimeter of the structure. The floor slab of the underground structure was not designed for water pressure. Thus, operation of the structure requires continuous pumping of seepage water collected at a sump located at the lowermost elevation within the structure. Subsurface investigation and monitoring data obtained over 5.75-year period following the construction of the structure indicated that the settlement resulted from consolidation of soft soils due to depressurization of an aquifer within the underlying bedrock caused by continuous dewatering needed for the operation of the structure. An analytical study was undertaken to project the long term settlement. A simple analytical model could be used to simulate the complex hydrogeological problem reasonably. The details of hydrogeologic setting, subsurface investigation and monitoring activities, and the analytical model for projecting long-term settlements are presented in this paper. 相似文献
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Characterising and modelling the excavation damaged zone in crystalline rock in the context of radioactive waste disposal 总被引：3，自引：0，他引：3
John A. Hudson A. Bäckström J. Rutqvist L. Jing T. Backers M. Chijimatsu R. Christiansson X.-T. Feng A. Kobayashi T. Koyama H.-S. Lee I. Neretnieks P.-Z. Pan M. Rinne B.-T. Shen 《Environmental Geology》2009,57(6):1275-1297
This paper describes current knowledge about the nature of and potential for thermo–hydro–mechanical–chemical modelling of the excavation damaged zone (EDZ) around the excavations for an underground radioactive waste repository. In the first part of the paper, the disturbances associated with excavation are explained, together with reviews of Workshops that have been held on the subject. In the second part of the paper, the results of a DECOVALEX [DEmonstration of COupled models and their VALidation against EXperiment: research funded by an international consortium of radioactive waste regulators and implementers (http://www.decovalex.com)] research programme on modelling the EDZ are presented. Four research teams used four different models to simulate the complete stress–strain curve for Avro granite from the Swedish Äspö Hard Rock Laboratory. Subsequent research extended the work to computer simulation of the evolution of the repository using a ‘wall-block model’ and a ‘near-field model’. This included assessing the evolution of stress, failure and permeability and time-dependent effects during repository evolution. As discussed, all the computer models are well suited to sensitivity studies for evaluating the influence of their respective supporting parameters on the complete stress–strain curve for rock and for modelling the EDZ. 相似文献
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The overturning failure of a 13 storey residential building in Shanghai, China, has been investigated by plane strain finite element analysis (FEA). The results of the FEA indicate that ultimate failure of the building was probably initiated by the formation of tensile cracking in the reinforced concrete piles located under the side of the building adjacent to an excavation. This eventually led to complete structural failure of the piles located along the excavation side, which probably caused further settlement of the building, leading eventually to a toppling failure resulting in overturning of the entire building. Excessive tensile stress in the piles was probably caused by the combination of excavation of soil at one side of the building and the temporary dumping of the excavated soil on the opposite side of the building. It is likely that the effect of temporary dumping of the excavated soil adjacent to the building was either not considered or not properly taken into account in the foundation design nor the construction operations. A simple but important lesson to be draw from this failure is the need for engineers who design foundations in soft soil regions to consider not only the final loading conditions, but also any temporary and transient loading conditions during the construction process. 相似文献
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This paper focuses on the derivation of an approximate analytical solution to predict ground surface settlements along the centre-line perpendicular to a slurry-supported diaphragm wall panel. An analytical model of trench excavation is constructed by applying linearly-distributed total earth pressure changes on the sidewalls and the base of the trench in a homogeneous, isotropic, elastic half-space. By applying the principle of superposition appropriately, an explicit solution to calculate ground surface settlements is derived by integrating Mindlin’s displacement formulae. The validity of the solution is verified by three-dimensional finite-element analyses and case studies. Based on the results obtained from a parametric study using the newly derived solution, an algebraic formula is obtained as a first approximation for calculating ground surface settlements. 相似文献