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71.
深圳是近20余年的时间高速建成的的新型现代化城市,成百上千座高层建筑坐落在罗湖断裂区域,因而研究罗湖建成区断裂带长期稳定性意义重大。通过对罗湖建成区两种典型的软弱岩石,含角砾泥岩和粉砂岩进行系统的室内流变实验研究,给出了适合罗湖破碎断裂带岩体的流变模型。选取罗湖断裂带轴部的核心断层——黄贝岭F8断层,运用得到的流变模型对黄贝岭F8断层的进行了长期稳定性计算。关键点的计算结果表明,在地面建筑物施工完成初期,断裂带将出现明显的竖直位移,竖直最大位移为7.797 6 cm , 水平位移最大值为0.950 1 cm。随着时间的延伸,竖直位移增量率由刚开始的每年0.63 cm降至0.21 cm;水平位移增量率由刚开始的每年0.047cm降至0.01 3 cm, 该断层对周边建筑的长期稳定性影响较小。 相似文献
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Investigation of the rheology of magmas at high crystal concentrations by experimental means has proved problematic. An alternative approach is to study textures of igneous rocks that not only preserve evidence of the kinematics of magma flow, such as flow direction, but can also preserve evidence of rheology. Flow textures in multiply intruded trachyte dykes on Fraser Island, eastern Australia record evidence of dilatant flow during solidification. This conclusion is reached by interpretation of microscopic ductile shear zones that disrupt the groundmass of aligned feldspar laths. Detailed three-dimensional investigation demonstrates that the dihedral angle between conjugate micro-shear zones is approximately 65°. This conjugate angle is equivalent to that observed in dilatant granular materials such as sand. Dilatant behaviour is synonymous with shear thickening rheology indicating that the magma flow is time-dependent and resists high flow rates. Some of the dykes contain autobrecciation fragments that may represent localities where the ductile flow rate threshold was exceeded. Newtonian or pseudoplastic (shear thinning) rheology of crystal-poor magmas must progressively give way to shear thickening rheology during cooling and increasing crystal concentration. 相似文献
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利用内蕴时间理论对土的流变性进行了理论研究。提出了在准三轴条件下土的流变本构方程 ,并且利用土的三轴流变试验结果对所得土流变本构方程进行了验证。验证结果表明用内蕴时间理论推导的土流变本构方程能很准确地描述土的流变性。 相似文献
76.
一个用于面板坝流变分析的堆石流变模型 总被引:21,自引:6,他引:15
在前人工作的基础上, 从宏观上建立了一个用于面板坝流变分析的堆石流变模型: 堆石的瞬时弹塑性变形由椭圆-抛物双屈服面模型确定,并计入时间效应, 由双曲线函数经验公式计算堆石与时间有关的粘塑性变形。通过现场实测结果的反分析验证了模型的可靠性。 相似文献
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Thermal Structure and Rheology of the Upper Mantle beneath Guangdong and Hainan Provinces, China 总被引:2,自引:0,他引:2
LIN Chuanyong SHI Lanbin Institute of Geology Seismological Bureau of China Beijing China HAN Xiuling Institute of Geology Chinese Academy of Sciences Beijing China CHEN Xiaode Institute of Geology Seismological Bureau 《Continental Dynamics》1999,(1)
1.Introduction Thethermalstateandrheologyoftheuppermantleareofgreatimportanceinunderstandingthestructureanddynamicsofthelithosphere,andevenforits3dimensionalor4dimensionalmapping(O’ReillyandGriffin,1985;O’Reillyetal.,1996;Xuetal.1995;Xuetal.,199… 相似文献
79.
福建明溪上地幔热结构及流变学特征 总被引:3,自引:0,他引:3
通过对采自福建明溪的幔源包体样品的详细研究,建立了该区上地幔的地温线,探讨其流变学特征。所获地温线高于大洋地温线,但稍低于中国东部和澳大利亚东南部地温线。由该地温线推导的壳幔边界为38km左右,但尖晶石二辉橄榄岩在32km左右即已开始出现,表明存在上地幔物质的底侵作用。同样,尖晶石二辉橄榄岩和石榴子石二辉橄榄岩包体平衡温度有所重叠,表明两者不是截然分开,其间存在有5 ̄10km的过渡带。包体的变形特 相似文献
80.
Stability and dynamics of the continental tectosphere 总被引:1,自引:0,他引:1
Continental cratons overlie thick, high-viscosity, thermal and chemical boundary layers, where the chemical boundary layers are less dense than they would be due to thermal effects alone, perhaps because they are depleted in basaltic constituents. If the continental tectosphere is the same age as the overlying Archaean crust, then the continental tectosphere must be able to survive for several billion years without undergoing a convective instability, despite being both cold and thick. Since platforms and shields correlate only weakly with Earth's gravity and geoid anomalies, acceptable models of the continental tectosphere must also satisfy this gravity constraint. We investigate the long-term stability of the continental tectosphere by carrying out a number of numerical convection experiments within a two-dimensional Cartesian domain. We initiate our experiments with a tectosphere (thermal and chemical boundary layers) immersed in a region of uniform composition, temperature, and viscosity, and consider the effects on the stability of the tectosphere of (1) activation energy (used to define the temperature dependence of viscosity), (2) compositional buoyancy, and (3) linear or non-linear rheology. The large lateral thermal gradients required to match oceanic and tectosphere structures initiate the dominant instability, a “drip” which develops at the side of the tectosphere and moves to beneath its center. High activation energies and high background viscosities restrict the amount and rate of entrainment. Compositional buoyancy does not significantly change the flow pattern. Rather, compositional buoyancy slows the destruction process somewhat and reduces the stress within the tectosphere. With a non-Newtonian rheology, this reduction in stress helps to stiffen the tectosphere. In these experiments, dynamical systems that adequately model the present ocean-continent structures have activation energy E*≥180 kJ mole−1 — a value about one third the estimate of activation energy for olivine, E*≈520 kJ mole−1. Although for E*≈520 kJ mole−1, compositional buoyancy is not required for the tectosphere to survive, the joint application of longevity and gravity constraints allows us to reject all models not containing compositional buoyancy, and to predict that the ratio of compositional to thermal buoyancy within the continental tectosphere is approximately unity. 相似文献