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821.
《China Geology》2020,3(1):124-136
Utilization of urban underground space has become a vital approach to alleviate the strain on urban land resources, and to optimize the structure and pattem of the city. It is also very important to improve the city environment, build livable city and increase the capacity of the city. Based on the analysis of existing evaluation methods and their problems, a method for evaluating underground space resources based on a negative list of adverse factors affecting underground space development is proposed, to be primarily used in urban planning stages. A list of the adverse factors is established, including limiting factors, constraining factors and influencing factors. Taking Xi’an as an example, using a geographical information system platform, a negative list of adverse factors for the underground space resources in Xi’ an City are evaluated, and preventive measures are proposed. Natural resources, exploitable resources, and the potential growth of exploitable underground space resources are evaluated. Underground space assessment in the different development stages of the city, collaborative utilization and safety evaluation for multiple subsurface resources, environmental impact and assessment, as well as evaluation methods based on big data and intelligent optimization algorithms are all discussed with the aim of serving city planning and construction. 相似文献
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Apart from some special cases, calculating the dynamic stiffness matrix of foundations on a layered half-space, especially for embedded foundations, is computationally expensive. An efficient method for two-dimensional foundations in a horizontally layered soil media is presented in this paper. This method is based on indirect boundary element methods and uses discrete wave number solution methods for calculating Green's functions for displacements and analytical methods for the integrations over the boundary. For surface foundations, the present method applies at all frequencies. For embedded foundations or for constructing energy transmitting boundaries, because the free-field part is modelled by boundary elements and the excavated part is modelled by finite elements, the present method applies only at low frequencies for the spring coefficients (the real parts of the dynamic stiffness matrix) but applies at all frequencies for the damping coefficients (the imaginary part of the dynamic stiffness matrix) for undamped sites. The novelty of the method can be used for three-dimensional foundations. © 1997 by John Wiley & Sons, Ltd. 相似文献
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The stability of end-bearing piles that are supported laterally along their entire length by an elastic Winkler foundation is investigated for the case when the coefficient of horizontal subgrade reaction varies linearly with depth. A pattern of clustering of buckling modes is shown to occur and the approximate modelling of the elastic foundation by averaging the stiffness of the subgrade is discussed. © 1997 by John Wiley & Sons, Ltd. 相似文献
825.
John P. Wolf 《地震工程与结构动力学》1997,26(9):931-949
The foundation on deformable soil, which, in general, radiates energy, can be represented in structural dynamics as a simple spring-dashpot-mass model with frequency-independent coefficients. For the two limiting cases of a site, the homogeneous half-space and the homogeneous layer fixed at its base, the coefficients are specified in tables for varying parameters such as ratios of dimensions and Poisson's ratio. Rigid foundations on the surface and with embedment are considered for all translational and rotational motions. In a practical analysis of soil–structure interaction this dynamic model of the foundation is coupled directly to that of the structure, whereby a standard dynamics program is used. © 1997 by John Wiley & Sons, Ltd. 相似文献
826.
Edge loaded annular foundations have been analysed assuming the soil pressure at the contact to be non-uniform using the lower bound approach of Limit Analysis. Variable fixity at the edges has been allowed and the foundation slab is made to follow the Square yield criterion. Results presented in the form of curves can be readily used to obtain the locations of the yield hinge circles for the given slab and the corresponding collapse load. © 1997 John Wiley & Sons, Ltd. 相似文献
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长期以来,我国采用分类管理的方式管理不同类型的自然资源,在自然资源监测监管中造成了部分自然资源重复统计、权属不明等问题,在湿地、林地等自然资源中表现尤其明显。为了系统性地进行自然资源监测监管,需要对自然资源进行整体性地、统一性地分类,建立一个综合性的自然资源分类体系。本文遵循“山水林田湖草”是一个生命共同体的理念,从这一理论思想出发,整理单门类自然资源整体和个体之间的关系,分析国内外的分类编码体系,从法理、学理和管理不同角度研究整理自然资源分类现状,综合考虑地表覆盖层的监测监管要求,采用树状分类法和交叉分类法重新构建了三级分类的自然资源分类体系框架,为构建自然资源监测监管体系提供必要的基础支撑,为完善生态文明建设,为国民经济健康持续发展提供重要的基础保障。 相似文献
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