浙东某山区危石加固实录     

程团结 《地质灾害与环境保护》2006,17(2):95-98

针对浙东某山区危石的危害、规模、分布特征和稳定状况,提出了支撑加固方案,经过比选优化,根据施工反馈信息的调整,最终采用人工挖孔桩支挡柱加固方案,施工后效果良好。本文详细介绍了治理的设计思路与施工过程。  相似文献   

Geochemical characteristics and Sr‐Nd‐Hf isotope compositions of Late Triassic post‐collisional A‐type granites in Sarudik,SW Sumatra,Indonesia     

Haikun Zhang  Peng Hu  Liang Cao  Armin Tampubolon  Asui Liu  Xiang Cheng  Mingguo Zhan  Luozhong Pan  Yu Dai  Beihong Pan 《Island Arc》2020,29(1)

Late Triassic A‐type granites are identified in this study in Sarudik, SW Sumatra. We present new data on zircon U–Pb geochronology, whole‐rock major and trace elements and Sr‐Nd‐Hf isotope geochemistry, aiming to study their petrogenesis and tectonic implications. LA‐ICP‐MS U–Pb dating of zircon separated from one biotite monzogranite sample yields a concordia age of 222.6 ±1.0 Ma, indicating a Late Triassic magmatic event. The studied granites are classified as weakly peralumious, high‐K calc‐alkaline granites. They exhibit high SiO₂, K₂O + Na₂O, FeO/(FeO + MgO) and Ga/Al ratios and low Al₂O₃, CaO, MgO, P₂O₅ and TiO₂ contents, with enrichment of Rb, Th and U and depletion of Ba, Sr, P and Eu, showing the features of A‐type granites. The granites have zircon ε_Hf(t) values from ?4.6 to ?0.4 and whole‐rock ε_Nd(t) values from ?5.51 to ?4.98, with Mesoproterozoic T_DM2 ages (1278–1544 Ma) for both Hf and Nd isotopes. Geochemical and isotopic data suggest that the source of these A‐type granites is the Mesoproterozoic continental crust, without significant incorporation of mantle‐derived component, and their formation is controlled by subsequent fractional crystallization. The Sarudik A‐type granites are further assigned to A2‐type formed in post‐collisional environment. Combined with previous knowledge on the western SE Asia tectonic evolution, we conclude that the formation of the Late Triassic A‐type granites is related to the post‐collisional extension induced by the crustal thickening, gravitational collapse, and asthenosphere upwelling following the collision between the Sibumasu and the East Malaya Block.  相似文献   

Modelling of R/C members accounting for shear failure localisation: Hysteretic shear model          下载免费PDF全文

Dimitrios K. Zimos  Panagiotis E. Mergos  Andreas J. Kappos 《地震工程与结构动力学》2018,47(8):1722-1741

Reinforced concrete (R/C) frame buildings designed according to older seismic codes represent a large part of the existing building stock worldwide. Their structural elements are often vulnerable to shear or flexure‐shear failure, which can eventually lead to loss of axial load resistance of vertical elements and initiate vertical progressive collapse of a building. In this study, a hysteretic model capturing the local shear response of shear‐deficient R/C elements is described in detail, with emphasis on post‐peak behaviour; it differs from existing models in that it considers the localisation of shear strains after the onset of shear failure in a critical length defined by the diagonal failure planes. Additionally, an effort is made to improve the state of the art in post‐peak shear response modelling, by compiling the largest database of experimental results for shear and flexure‐shear critical R/C columns cycled well beyond the onset of shear failure and/or up to the onset of axial failure, and developing empirical relationships for the key parameters defining the local backbone post‐peak shear response of such elements. The implementation of the derived local hysteretic shear model in a computationally efficient beam‐column finite element model with distributed shear flexibility, which accounts for all deformation types, will be presented in a companion paper.  相似文献   

Modelling of R/C members accounting for shear failure localisation: Finite element model and verification          下载免费PDF全文

Dimitrios K. Zimos  Panagiotis E. Mergos  Andreas J. Kappos 《地震工程与结构动力学》2018,47(7):1631-1650

Reinforced concrete (R/C) frame buildings designed according to older seismic codes represent a large part of the existing building stock worldwide. Their structural elements are often vulnerable to shear or flexure‐shear failure, which can eventually lead to loss of axial load resistance of vertical elements and initiate vertical progressive collapse of a building. In this study, a computationally efficient member‐type finite element model for the hysteretic response of shear critical R/C frame elements up to the onset of axial failure is presented; it accounts for shear‐flexure interaction and considers, for the first time, the localisation of shear strains, after the onset of shear failure, in a critical length defined by the diagonal failure plane. Its predictive capabilities are verified against experimental results of column and frame specimens and are shown to be accurate not only in terms of total response, but also with regard to individual deformation components. The accuracy, versatility, and simplicity of this finite element model make it a valuable tool in seismic analysis of complex R/C buildings with shear deficient structural elements.  相似文献   

2017年8月9日精河6.6级地震灾害损失及灾后恢复重建经费评估     

阿里木江&#;亚力昆  常想德  孙静  李帅  胡伟华 《中国地震》2017,33(4):781-788

2017年8月9日新疆精河发生6.6级地震,地震造成36人受伤,各类房屋建筑、公共服务设施、基础设施等遭受不同程度的破坏。通过实地抽样调查,按照国家标准的原则和方法,评估出此次地震造成的直接经济损失为429964万元,灾后恢复重建经费约需538461万元。  相似文献   

Fundamental yet simplified model for liquefaction instability     

Chandra S. Desai  Innjoon Park  Changming Shao 《国际地质力学数值与分析法杂志》1998,22(9):721-748

A fundamental procedure is proposed for the identification of liquefaction in saturated soils based on the instability in the material's microstructure. The disturbed state concept (DSC) provides a unified constitutive model for the characterization of entire stress–strain behaviour under cyclic loading, and the values of disturbance at threshold states in the deforming microstructure provides the basis for the identification of liquefaction. The procedure is verified with respect to laboratory behaviour of two sands, saturated Ottawa and Reid Bedford. A mathematical analysis of the DSC constitutive matrix is also performed. Procedures for the application of the DSC for simplified analysis and design, and in finite element procedures are presented. It is believed that the proposed model can provide a fundamental yet simplified procedure for liquefaction analysis, and as a result, it is considered to be an improvement over the available empirical and energy-based procedures. © 1998 John Wiley & Sons, Ltd.  相似文献   

参数型岩石几何损伤模型的构建及其应用研究     

张超  白允 《岩土力学》2020,41(12):3899-3909

岩石几何损伤模型是建立统计损伤本构模型的重要基础。在岩石变形力学特性基础上对现有岩石几何损伤模型进行了回顾性分析,针对它们难以较好地反映初始损伤特征和峰后变形破坏特征的缺陷与不足,首先,将岩石材料视为由未损伤部分、初始损伤部分和后继损伤部分组成,提出了考虑初始损伤的岩石几何损伤模型;然后,通过探讨Weibull分布参数m和F0对损伤变量变化产生的影响,构建了参数型岩石几何损伤模型,在此基础上建立了应变软化类岩石统计损伤本构模型并进行了修正,给出了模型参数的确定方法;最后,通过模型验证和参数分析表明,修正后模型能够较好地模拟岩石变形破裂全过程,参数l和h对损伤变量变化产生的影响与m和F0等效,解决了现有岩石几何损伤模型存在的共性问题,该模型和方法具有一定的合理性和可行性。  相似文献   

40Ar/39Ar Thermochronological Constraints on the Timing of Collisional Orogeny in the Mian-Lüe Collision Belt,Southern Qinling Mountains     

LI Jinyi  WANG Zongqi  ZHAO Min 《《地质学报》英文版》1999,73(2):208-215

Silurian, Devonian and Carboniferous geological bodies in the Mianxian-Lüeyang (Mian-Lüe) collisional belt (MLB) and its neighbouring areas, southern Qinling Mountains, China, show similar characteristics of having undergone deformation of two stages. The earlier one, which is inferred to be related to collisional orogeny between the Yangtze and Sino-Korean palaeocontinents based on previous geological data, is responsible for large-scale, north-verging recumbent folds and overthrusts, and associated with low greenschist facies metamorphism. 40Ar/39Ar dating of three muscovite samples taken from different localities yields plateau ages of 226.9(0.9 and 219.5(1.4 Ma and an apparent age of 194.5(3.0 Ma. Thus, the late Triassic collision between the Yangtze and Sino-Korean palaeocontinents has been constrained.  相似文献   

钻孔灌注桩后压浆技术在上海地区的试验   总被引：6，自引：1，他引：5       下载免费PDF全文

陶兴文  吴礼生 《探矿工程》1999,(6):4-5

介绍了钻孔灌注桩后压浆在上海地区桩基工程中的试验情况,并对试验结果进行分析,提出了后压浆技术应用过程中值得注意的有关技术措施和做法。  相似文献   

后压浆提高钻孔灌注桩承载力的初步研究(上)   总被引：4，自引：0，他引：4       下载免费PDF全文

王鸿 《探矿工程》1999,(3):14-16

依据有关理论及公式,通过对某地试桩结果及大量的地质资料和数据进行归纳整理,推导出一个在一定条件下的后压浆桩的单桩竖向极限承载力的计算公式,经与实际检测结果相比较,趋于吻合。  相似文献