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排序方式: 共有340条查询结果,搜索用时 14 毫秒
1.
Mahdi Shadab Far Yuan Wang Yousif A. H. Dallo 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2019,13(1):82-98
Rock explosion has always been a complex problem because neither rock characteristics nor explosion waves could be accurately estimated. As such, this imposes a high uncertainty on deterministic methodologies available for damage prediction. In this paper, by defining two damage zones around the blast hole, including crushed and cracked zones, a first-order reliability analysis (FORM) was adopted to address this issue. For this purpose, FORM was used in a double-loop algorithm, where the inner loop was responsible for converging the FORM, and the outer loop was assigned to feed the inner loop with new cases. Using such nested-loop algorithm, the probability of exceedance was calculated for any desired damage zone radius. The maximum effect of the involved parameters on the failure probability induced around the blast hole was additionally studied using a parametric reliability analysis. The results showed that the radii for crushed and cracked zones are limited to 0.5 and 4.2?m, respectively, so that the probability of going beyond these limits is less than 1%. Moreover, the analyses of decoupled explosions showed that increasing the gap between the explosion charge and wall of the borehole could severely reduce the failure probability; however, the maximum effect of decoupling ratio occurs in the small range of radii between 0.3?mm and 2.35?m. 相似文献
2.
《Comptes Rendus Geoscience》2018,350(8):452-463
Fracture process is investigated using finite-difference simulations with a new constitutive model. It is shown that both geometry and fracture mechanism itself depend on the preexisting heterogeneities that are stress concentrators. In the brittle regime (low pressure, P), Mode-I fractures propagate normal to the least stress σ3 from the imposed weak zones. At high P, shear deformation bands are formed oblique to σ3. At intermediate values of P, the fracture process involves both shear banding and tensile cracking and results in the initiation and propagation of pure dilation bands. The propagating band tip undulates, reacting on the failure mechanism changes, but its global orientation is normal to σ3. The σ3-normal fractures are joints. There are thus two types of joints resulting from Mode-I cracking and dilation banding, respectively. The obtained numerical results are in good agreement with and explain the results from previous similar experimental study. 相似文献
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The impact of dropped anchor on submarine photoelectric composite cables may possibly cause electrical faults, i.e. electricity and optical signal transmission failure. In order to study the impact capacity and structural impact failure mechanism, a test setup is designed originally to examine the structural and functional integrity. A detailed finite element model (FEM) is created, considering material nonlinearity and component interaction. A parametric analysis has been performed to predict the deformation of components and impact forces, under different impact velocities and collision directions. Relationships between the armor layer indentation rate and that of internal power and optical units are achieved. The impact deformation of internal entities can be evaluated intuitively by armor layer indentation. The proposed experimental and numerical methods are well correlated, suitable to assess the impact capacity of subsea power cables and assist the protection design of subsea power cables in engineering. 相似文献
5.
青海东南部农村民居结构特点及抗震能力分析 总被引:1,自引:1,他引:0
我国农村民居的抗震能力具有显著的地域特点。本文基于现场调研结果总结了青海东南部黄河流域农村民居的结构特点,并对其抗震能力进行了评估。庄廓院是调研区内的典型农村民居,本文对调研区内庄廓院的木构架房屋进行研究,提出庄廓土墙围护木构架房屋的震害等级分类标准,根据实际震害资料和类比的方法确定了当地土墙围护木构架结构的震害矩阵和震害指数与峰值加速度的关系曲线。与云南鲁甸农村的土木结构房屋比较,青海庄廓院民居具有更高的抗震能力;与未设防的砖混结构比较,这种土墙围护的木构架结构在高烈度区造成人员伤亡的风险更低。 相似文献
6.
This paper expounds the features of the buildings and analyzes the seismic disaster characteristics of the Jiuzhaigou M_S7. 0 earthquake in the area between Songpan and Jiuzhaigou. New buildings (especially the frame structure) had good anti-seismic performance,but brick-wood structures and brick-concrete structures sustained large amounts of damage in the earthquake. By computing the seismic damage index,we found that the seismic damage index of the frame structure was far less than that of civil structures and brick-wood structures. The seismic damage index of frame structures were all zero in the Ⅵ area,and increased rapidly with the increase of intensity,but the increasing range was reduced. We also discussed how to evaluate the intensity in areas where there was a lack of buildings or there was only one structure type,which can be referenced in future field work. 相似文献
7.
M. Erdik K. ŞeşetyanM.B. Demircioğlu U. HancılarC. Zülfikar 《Soil Dynamics and Earthquake Engineering》2011
This article summarizes the work done over the last decades regarding the development of new approaches and setting up of new applications for earthquake rapid response systems that function to estimate earthquake losses in quasi-real time after an earthquake. After a critical discussion of relevant earthquake loss estimation methodologies, the essential features and characteristics of the available loss estimation software are summarized. Currently operating near-real-time loss estimation tools can be classified under two main categories depending on the size of area they cover: global and local systems. For the global or regional near-real-time loss estimation systems: GDACS, WAPMERR, PAGER, and NERIES-ELER methodologies are presented together with their loss estimations for the 2009 Abruzzo (L’Aquila) earthquake in Italy. Examples are provided for the local rapid earthquake loss estimation systems, including the Taiwan Earthquake Rapid Reporting System, Real-time Earthquake Assessment Disaster System in Yokohama, Real Time Earthquake Disaster Mitigation System of the Tokyo Gas Co., and Istanbul Earthquake Rapid Response System. 相似文献
8.
不良工程地质组合导致房屋地基开裂或滑移,墙体承重失衡导致房屋结构性破裂。煤矿开采直接导致地下水位下降,部分影响建筑物地基稳定性及地面塌陷。 相似文献
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10.
《Geoforum》2014
This article explores how standards and codes for collaboration in international higher education influence the educational space of global online education and the way it functions within the context of international development aid. Firstly the article discusses the educational space of higher education and the geography of education whereby the aim is to situate global online education within the on-going discourse on standards in higher education, international development aid, and the knowledge economy. The article then examines a qualitative case study of an Internet-based masters programme attended by students from Europe and Africa. A main focus of the empirical analysis is the students’ experience of being geographically immobile while collaborating online internationally, including how this circumstance affected their motivation and participation and the benefits of the programme. In the concluding discussion it is argued that even though online collaboration among students and educational institutions is not entirely equal, common standards created a space in which positions were challenged and practices were changed over the course of online participation. 相似文献