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981.
三层地铁车站振动台试验分析 总被引:3,自引:0,他引:3
为了探究多层地下结构地震破坏机理,进行了三层地铁车站振动台试验.试验采用微粒混凝土模型,严格按照相似比和配筋率对模型进行加筋配置.填土采用哈尔滨地铁施工挖掘出的扰动土.装土箱采用自主研制的层叠剪切箱以减小边界效应.通过对试验加速度和应变的分析可得到以下主要结论:(1)地下结构在地震中的破坏,主要是由位移控制的;(2)多... 相似文献
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为了探测危害煤矿安全生产的地质体,如断层、褶曲、煤层变薄区、陷落柱等,研制了一套符合防爆要求的分布式煤矿高密度电阻率仪。仪器中设计了电流、电压两个各自独立的通道,每通道设计两级低通有源滤波和两级工频陷波,以及高分辨24位模数转换器,提高了抗干扰能力和测量精度。设计了轻便智能分布式电极系,可灵活组成二维测量系统,施工方便。整机按照防爆要求设计,适合煤矿井下勘测。 相似文献
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XU Xueyi CHEN Junlu LI Xiangmin MA Zhongping WANG Hongliang LI Ping LI Ting 《《地质学报》英文版》2011,85(6):1336-1350
On the basis of petrogeochemical data, the volcanic lavas of the Baimianxia Formation can be classified into two units: high TiO2 and low TiO2. The TiO2 concentration of the former is generally higher than 1%, which occurs in the lower part with high-grade metamorphism, but the latter is less than 1% and crops out in the upper part with low-grade metamorphism. The high-TiO2 unit is dominated by tholeiitic lavas showing high rare earth element (REE) contents (ΣREE?=?83.4–180.8?μg/g), high light/heavy REE (LREE/HREE) ratios (LREE/HREE=2.17–5.85) and weak negative Eu anomaly (Eu=0.79–1.01). Its trace element patterns display weak Nb-Ta anomalies with respect to Th, K, La, Ce, showing within-plate basalt affinities. In contrast, the low-TiO2 unit is characterized by low REE contents, low LREE/HREE ratios, and pronounced Nb-Ta anomalies, indicating typical arc or continental arc signature. Chondrite-normalized REE patterns of basalts and andesites from the Sanwan Formation are flat or LREE depletion, which is very similar to normal mid-oceanic basalt. Therefore, we suggest that these lavas should be formed in a back-arc basin setting. Sr-Nd isotopic data of the basalt in the lower part suggest that the rocks would have been formed in ~1144?Ma. Based on the geochemical and isotopic features of the basalts, we suggest that these rocks in the low part of the Baimianxia Formation should originate from an asthenospheric oceanic-island basalt-like mantle source, which may be produced by partial melting of garnet lherzolite, and significantly underwent fractional crystallization and crustal or lithospheric mantle contamination en route to the surface. However, laser ablation inductively coupled plasma mass spectrometry zircon U-Pb dating of the basalt sample from the upper part of the Baimianxia Formation gives a 437 Ma, indicating a Early Paleozoic age. The geochemical analysis in this paper suggests that they may originate from an arc or continental arc in response to aqueous fluids or melt expelled from a subducting slab, and the partial melting occurred in the garnet stability field. The samples of basalts and andesites in the Sanwan Formation show they are derived from depleted mantle source similar to normal mid-oceanic basalt. Finally, we can conclude that the lavas in the lower part of the Baimianxia Formation represent the geological records of rift-related volcanism in the middle Proterozoic, which is commonly considered to be the precursor of continental breakup and followed by oceanic basin forming from Neoproterozoic to early Paleozoic. Whereas, the lavas in upper part of the Baimianxia Formation and Sanwan Formations may have been generated by the oceanic and continental conversion that occurred in the early Paleozoic. 相似文献
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