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1.
To assess the post-earthquake seismic safety of buildings, it is crucial to predict seismic response, and it is necessary to set the appropriate physical parameters of the response analysis model. Numerous methods have been proposed to identify physical parameters. However, most of them are limited to linear systems, and previous researches on nonlinear systems have difficulties in practical applications. In this paper, a nonlinear response analysis model is identified for a full-scale ten-story reinforced concrete building with the degrading tri-linear stiffness model by the modal iterative error correction (MIEC) method, and the accuracy of this technique is discussed by comparing with the shaking table test.  相似文献   
2.
高速远程滑坡物理模型试验中,岩石相似材料的选择是模型试验成功的关键,然而目前滑坡相似材料强度高、难以在缩尺试验中模拟滑坡破碎过程。以重晶石、石英砂为骨料,石膏为胶结剂,羧甲基纤维素钠、甘油、水作为辅助材料,进行可破碎岩石相似材料的配比试验。采用控制变量法研究重晶石与石英砂比例(重石比)、骨料与胶结物比例(骨胶比)、羧甲基纤维素钠含量、拌合水量、甘油含量对相似材料物理力学性质的影响。试验结果表明:所有配比情况下各相似材料物理力学参数的范围分别为单轴抗压强度为0.12~1.47 MPa,弹性模量为25.51~148.12 MPa,黏聚力为1.63~87.39 kPa,内摩擦角为22.70°~35.89°,脆性指标主要分布在0.033~0.145之间;重石比主要控制岩石相似材料的内摩擦角;骨胶比减小,对应的黏聚力和内摩擦角先增大后减小;羧甲基纤维素钠对材料的单轴抗压强度、弹性模量、黏聚力等材料的力学特性以及材料的脆性指标影响均比较大,其中对单轴抗压强度的影响最大。因此,控制羧甲基纤维素钠和拌合水量的含量,并合理调节重石比与骨胶比,在相似比约为1∶600的试验尺度下,最终确定了适用于高速远程滑坡碎屑化过程模拟的低强度高脆性岩石相似材料的配比区间。  相似文献   
3.
Studies on recent earthquakes highlighted that buildings with minimal structural damage still suffer from extensive damage and failure of nonstructural components. The dropping and damage of suspended ceiling systems, which typically consist of acceleration-sensitive nonstructural elements, resulted in lengthy functional disruptions and extended recovery time. This article experimentally and analytically examined the vibration properties of an integrated ceiling system considering the interactions with surrounding electrical equipment. The theoretical stiffness and corresponding frequency of electrical equipment were initially derived and then verified by subsequent vibration tests and numerical analyses. The seismic performance of the air conditioner (AC) was evaluated with different installment configurations based on design spectra and floor response spectra. Vibration tests of the suspended integrated ceiling system considering the interactions with surrounding equipment showed that the inclusion of peripheral constraints increased the first horizontal vibration frequency of the ceiling system by a factor of approximately 6. The natural frequencies of all components in the integrated ceiling system were almost identical, which was attributed to the coupled behavior between the ceiling panels and surrounding equipment, emphasizing the effect of interactions between adjacent components during dynamic analysis. Based on the above experimental investigation, an associated numerical model of the integrated ceiling system was created. Finally, corresponding parametric studies that included the interactions with surrounding equipment, reinforcing braces of ACs and strengthening members at the rise-up location between two elevations were performed.  相似文献   
4.
To investigate the seismic response of a pile group during liquefaction, shaking table tests on a 1/25 scale model of a 2 × 2 pile group were conducted, which were pilot tests of a test project of a scale-model offshore wind turbine with jacket foundation. A large laminar shear box was utilized as the soil container to prepare a liquefiable sandy ground specimen. The pile group model comprising four slender aluminum piles with their pile heads connected by a rigid frame was designed with similitude considerations focusing on soil–pile interaction. The input motions were 2-Hz sinusoids with various acceleration amplitudes. The excess pore water pressure generation indicated that the upper half of the ground specimen reached initial liquefaction under the 50-gal-amplitude excitation, whereas in the 75-gal-amplitude test, almost entire ground was liquefied. Accelerations in soil, on the movable frames composing the laminar boundary of the shear box, and along the pile showed limited difference at the same elevation before liquefaction. After liquefaction, the soil and the movable-frame accelerations that represented the ground response considerably reduced, whereas both the movable frames and the piles exhibited high-frequency jitters other than 2-Hz sinusoid, and meantime, remarkable phase difference between the responses of the pile group and the ground was observed, all probably due to the substantial degradation of liquefied soil. Axial strains along the pile implied its double-curvature bending behavior, and the accordingly calculated moment declined significantly after liquefaction. These observations demonstrated the interaction between soil and piles during liquefaction.  相似文献   
5.
王建伟 《探矿工程》2021,48(3):73-77
为更好地服务深部钻探工程,准确了解冲洗液封堵性能,对6种成膜封堵剂开展了砂床实验、API静失水量实验、流变性能实验及抗温实验等室内实验进行优选与评价。实验结果表明,2号和4号成膜封堵剂在6种成膜封堵剂中封堵性能最好,它们在基浆中的最优加量均为2%,100 ℃温度条件下加入这2种封堵剂的冲洗液具有较好的抗温性能;冲洗液中膨润土含量和处理剂是影响冲洗液封堵性能的2个重要因素:膨润土含量越高,冲洗液封堵性能越好,加入聚合物、降滤失剂等处理剂可以提高冲洗液的封堵性能。砂床实验是评价冲洗液封堵性能好坏的重要依据。  相似文献   
6.
The lack of sufficient direct observation data of typhoon fine structure is the main bottleneck that restricts the further development of typhoon discipline and forecasting. This paper briefly introduced the basic information of the National Key R&D Program of China, entitled “Experiment on Coordinated Observation of Offshore Typhoon in China”, which started in early 2019. Firstly, the importance and necessity of the program around the national needs on typhoon-related disaster reduction and prevention were explained. Then, the coordinated observation difficulties and frontiers in the current typhoon discipline situation from the development and improvement of the physical mechanism and key forecasting technologies were shown. The overview of the direct observation instrument and platform, the field campaign and the parameterization techniques related to physical process in typhoon numerical modeling was provided. Finally, the key scientific and technical issues and main research contents of the program were given.  相似文献   
7.
地震时砌体结构窗间墙易发生破坏,为了提高其抗震性能,对高宽比为1的2组共4片墙体,其中:2片为双层打包带加固墙体,2片为原墙,进行了拟静力试验,研究墙体的破坏形态、水平承载力、滞回曲线和耗能等抗震性能。试验发现原墙发生剪切破坏,加固后墙体发生摇摆破坏,加固改变了墙体破坏模式,加固后墙体滞回曲线饱满但有捏笼,破坏荷载、延性和耗能能力都有提高,破坏时未发生剥离,表明双层打包带加固法有效地提高了窗间墙体抗震性能,对承受较大竖向应力墙体效果更好,建议加固时要加强加固层与窗下和窗上墙体的连接。  相似文献   
8.
不同顶管组合方式的管幕冻结温度场模型试验   总被引:1,自引:1,他引:0  
拱北隧道作为港珠澳大桥珠海连接线的关键性工程, 在国内外首次成功运用了管幕冻结技术。以此为背景, 为更加全面地掌握饱和软土地层中管幕冻结温度场的分布特点, 开展了不同顶管组合方式下的管幕冻结温度场模型试验研究。试验结果表明: 各测点温度曲线在积极冻结期前4 h急剧下降, 随后逐渐减缓, 降至砂土冰点后趋于平稳, 三种布管方式均满足冻结设计要求; 冻结管中低温盐水提供的冷量首先传递给顶管管壁, 再以“面”的形式均匀地传递给周围土体; 积极冻结21 h后, 采用四根空顶管组合的C区冻结壁竖向范围最大, 空管管壁正上方冻结壁平均厚度约为105 mm, 在满足管幕刚度设计要求的前提下, 可采此布管方式以达到快速形成冻结帷幕的目的。限位管开启后的4 h内, 实顶管中线垂直距离100 mm范围内测点温度曲线虽有明显回升但仍维持在冻土冰点以下, 超出此范围后温度变化影响逐渐减弱, 且顶管间冻结壁稳定存在, 表明限位管在满足管间有效封水的条件下, 能在一定范围内起到定向限制地层冻胀的作用。优化后的双圆形冻结管在满足冻结设计要求的同时, 更加便于安装且经济环保。  相似文献   
9.
为了更全面地分析筋土界面相互作用特性,改制了一台可视加筋土界面特性宏细观分析的试验仪器,可开展不同土工合成材料与填料的直剪和拉拔试验;该仪器改进了试验箱的尺寸,可方便两种试验的对比分析,增加了图像摄录系统,可进行试验过程的细观分析。使用新研制仪器分别进行了土工合成材料(土工格栅和土工布)加筋尾矿砂的直剪和拉拔试验,试验结果表明:两种试验条件下,土工格栅与尾矿的界面参数(似黏聚力和似摩擦角)及似摩擦系数均比土工布与尾矿的界面参数和似摩擦系数大;直剪试验下筋材网孔的有无对筋-尾矿界面参数均有较大影响,拉拔试验下筋材网孔有无对筋-尾矿界面参数似黏聚力的影响较为显著,对似摩擦角的影响较小。随着宏观变量法向应力的增加,细观参数孔隙率减小,平均接触数增加,反映在宏观上的现象就是填料颗粒被压密,筋材需要克服的阻力增大。该试验仪器能够较好地分析筋土界面宏细观特性,获得关键技术指标以用于加筋结构的设计。   相似文献   
10.
The fossil echinoderms of the Lower Carboniferous (Mississippian) of Derbyshire remain understudied, principally due to the nature of the preservation rather than any lack of biodiversity. Echinoids and crinoids are described in float blocks of limestone from near Hurdlow, Derbyshire, which have been etched naturally after many years of being washed by weakly acidic rain. Surface detail is variable, commonly poor, but rare specimens retain enough features for tentative identification. Two species of echinoids are identified from rare disarticulated plates, namely Melonechinus? sp. (ambulacral plates) and archaeocidarid sp. (interambulacral plate); more and superior material will be necessary to confirm this division. Crinoids include a cladid brachial ossicle sp. with a distinctive sculpture; a columnal of a monobathrid camerate platycrinitid sp.; Annulocolumnus (col.) sp. cf. A. annulus Donovan, a columnal morphotaxon with an unusually broad axial canal; and Cyclocyclicus (col.) spp. This is the tenth echinoid site to be recognized from the Mississippian of the White Peak. Examination of etched float blocks provides a further method of investigation of the echinoderm fauna of this and other limestone areas.  相似文献   
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