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731.
用球谐函数方法(SHM)计算了由Schwiderski海潮图和日本海海潮图引起的M2,S2,K1和O1各分潮波的综合海潮负荷参数.计算中采用了Pagiatakis(1990)地球模型的负荷Love数.结果表明SHM具有更高的计算效率和计算精度.为了真正实现±毫米的VLBI地壳运动测定精度和±0.1微伽的绝对重力测量精度,对未来海潮图模型,特别是日本海的海潮图模型的精度要求作了讨论.计算结果还表明不同地球模型的负荷Love数对计算的测站位移之差为0.7毫米,在目前测量精度下尚可以不作考虑.中国近海的海潮M2波对台北,上海,Daejeon,Okinawa,和Kagosima站的径向和水平分量位移影响可分别达±22.4~±1.0毫米和±05-±5.5毫米,表明中国近海高精度的海潮图模型对东亚测站的地壳运动高精度测量是十分重要的. 相似文献
732.
文章通过几项实例,指出在进行水压爆破施工确定药量和药包分布、布置时要充分考虑构筑物的结构与形状特点,并根据其特点对计算参数值要予以相应调整,同时还指出单位体积药量值随构筑物长宽比的不同而变化,可为类似工程施工提供参考。 相似文献
733.
高温后混凝土在重复荷载作用下的应力—应变关系 总被引:3,自引:0,他引:3
本文通过对遭受100 ̄800℃高温作用后的混凝土棱柱体进行轴压重复荷载作用下的强度和变形试验,研究了高温后混凝土加载及卸载应力-应变曲线的特征,建立了相应关系的数学表达式。文中并就高温和荷载两种作用对混凝土损伤的影响作了讨论。 相似文献
734.
李应平 《地震学报(英文版)》1996,9(3):377-387
Microearthquakeanalysisforhydraulicfrac┐turingprocesYING-PINGLI(李应平)DepartmentofEarth,AtmosphericandPlanetarySciences,Masach... 相似文献
735.
The arcuate nappe structure on the north edge of the Wuliang Mountains in westernYunnan Province is a complex nappe structural system with multiple superimposed structures.The autochthonous system is a WNW-trending arcuate fold belt consisting of the Jurassic andCretaceous and the allochthonous system is mainly composed of Upper Triassic rocks. Generally,the nappe structure moved from south to north, with the hanging wall thrusting in a WNW direc-tion for a distance of over 10km. The deep nappe structural system was formed at depths ofabout 5-10km in an environment not exceeding the greenschist facies. It occurred in theOligocene (about 40-20 Ma). 相似文献
736.
地下洞室围岩应力的测量研究 总被引:3,自引:2,他引:3
介绍了在地下洞室不同方向的钻孔中,采用水力劈裂技术进行的原位地应力测量。结合广西全州天湖水电站,广州抽水蓄能电站和广西龙滩水电站的实测结果,分析研究了地下洞室围岩应力的分布状态及影响围岩应力分布的主要因素。 相似文献
737.
Two of the four wells monitored near Parkfield, California, during 1985 showed water level rises beginning three days before theM
w
6.1 Kettleman Hills earthquake. In one of these wells, the 3.0 cm rise was nearly unique in five years of water level data. However, in the other well, which showed a 3.8 cm rise, many other changes of comparable size have been observed. Both wells that did not display pre-earthquake rises tap partially confined aquifers that cannot sustain pressure changes due to tectonic strain having periods longer than several days. We evaluate the effect of partial aquifer confinement on the ability of these four wells to display water level changes in response to aquifer strain. Although the vertical hydraulic diffusivities cannot be determined uniquely, we can find a value of diffusivity for each site that is consistent with the site's tidal and barometric responses as well as with the rate of partial recovery of the coseismic water level drops. Furthermore, the diffusivity for one well is high enough to explain why the preseismic rise could not have been detected there. For the fourth well, the diffusivity is high enough to have reduced the size of the preseismic signal as much as 50%, although it should still have been detectable. Imperfect confinement cannot explain the persistent water level changes in the two partially confined aquifers, but it does show that they were not due to volume strain. The pre-earthquake water level rises may have been precursors to the Kettleman Hills earthquake. If so, they probably were not caused by accelerating slip over the part of the fault plane that ruptured in that earthquake because they are of opposite sign to the observed coseismic water level drops. 相似文献
738.
739.
R. Kerrich 《Pure and Applied Geophysics》1986,124(1-2):225-268
Fluid infiltration into fault zones and their deeper-level counterparts, brittle-ductile shear zones, is examined in diverse tectonic environments. In the 2.7 Ga Abitibi greenstone belt, major tectonic discontinuities, with lateral extents of hundreds of kilometres initiated as listric normal faults accommodating rift extension and acted as sites for komatiite extrusion and locally intense metasomatism. During reverse motion on the structures, accommodating shortening of the belt, these transcrustal faults were utilised as a conduit for the ascent of trondhjemitic magmas from the base of the crust and of alkaline magmas from the asthenosphere and for the discharge of thousands of cubic kilometres of hydrothermal fluids. Such fluids were characterised by 18O=+6±2, D=–50±20, 13C=–4±4, and temperatures of 270 to 450°C, probably derived from devolatilisation of crustal rocks undergoing prograde metamorphism. Hydrothermal fluids were more radiogenic (87Sr/86Sr=0.7010 to 0.7040) and possessed higher than did contemporaneous mantle, komatiites or tholeiites, and thus carried a contribution from older sialic basement. A provinciality of87Sr/86Sr and 13C is evident, signifying that fault plumbing sampled lower crust which was heterogeneous at the scale of tens of kilometres. Mineralised faults possess enrichments of large ion lithophile (LIL), LIL elements, including K, Rb, Ba, Cs, B, and CO2, and rare elements, such as Au, Ag, As, Sb, Se, Te, Bi, and W. Fluids were characterised by XCO
20.1, neutral to slightly acidic pH, low salinity 3 wt-%, K/Na=0.1, they carried minor CH4, CO, and N2, and they underwent transient effervescence of CO2 during decompression. Clastic sediments occupy graben developed at fault flexures. The40Ar/39Ar release spectra indicate that fault rocks experienced episodic disturbance on time scales of hundreds of millions of years.At the Grenville front, translation was accommodated along two mylonite zones and an intervening boundary fault. The high-temperature (580°C) and low-temperature (430 to 490°C) mylonite zones, formed in the presence of deep-level crust-equilibrated fluids of metamorphic origin. Late brittle faults contain quartz veins precipitated from fluids with extemely negative 18O (–14 per mil) at 200 to 300°C. The water may have been derived from downward penetration into fault zones of precipitation of low18O on a mountain range induced by continental collision, with uplift accommodated at deep levels by the mylonite zones coupled with rebound on the boundary faults.Archean gneisses overlie Proterozoic sediments along thrust surfaces at Lagoa Real, Brazil; the gneisses are transected by brittle-ductile shear zones locally occupied by uranium deposits. Following deformation at 500 to 540°C, in the presence of metamorphic fluids and under conditions of low water-to-rock ratio, shear zones underwent local intense oxidation and desilication. All minerals undergo a shift of –10 per mil, indicating discharge of meteoric-water-recharged formation brines in the underlying Proterozoic sediments up through the Archean gneisses, during overthrusting; 1000 km3 of solutions passed through these structures. The shear zones and Proterozoic sediments are less radiogenic (87Sr/86Sr=0.720) than contemporaneous Archean gneisses (0.900), corroborating the transport of fluids and solutes through the structure from a large external reservoir.Major crustal detachment faults of Tertiary age in the Picacho Cordilleran metamorphic core complex of Arizona show an upward transition from undeformed granitic basement through mylonitic to brecciated and hydrothermally altered counterparts. The highest tectonic levels are allochthonous, oxidatively altered Miocene volcanics. This transition is accompanied by an increase of 12 per mil in 18O, from +7 to +19, and a 400°C decrease in temperature. Lower tectonic levels acted as aquifers for the expulsion of large volumes of higher-temperature reduced metamorphic fluids and/or evolved formation brines. The Miocene allochthon was influenced by a lower-temperature reservoir inducing oxidative potassic alteration; mixing occurred between cool downward-penetrating thermal waters and the hot, deeper aqueous reservoir.In general, flow regimes in these fault and shear zones follow a sequence, from conditions of high temperature and pressure with locally derived fluids at low water-to-rock ratios, during initiation of the structures, to high fluxes of reduced formation or metamorphic fluids along conduits as the structures propagate and intersect hydrothermal reservoirs. Later in the tectonic evolution and at shallower crustal levels there was incursion of oxidising fluids from near-surface reservoirs into the faults. In general, magmatism, tectonics, and fluid motion are intimately related. 相似文献
740.