Shake table testing of a multi-tower connected hybrid structure

Many single-tower reinforced concrete core wall-steel frame (RCC-SF) buildings have been built in China, but there are no buildings of different-height multi-tower hybrid system. A multi-tower RCC-SF tall building was thus studied because of its structural complexity and irregularity. First, a 1/15 scaled model structure was designed and tested on the shake table under minor, moderate, and major earthquake levels. Then, the dynamic responses of the model structure were interpreted to those of the prototype structure according to the similitude theory. Experimental results demonstrate that, despite the complexity of the structure, the lateral deformation bends as the "bending type" and the RC core walls contribute more than the steel frames to resist seismic loads. The maximum inter-story drift of the complex building under minor earthquakes is slightly beyond the elastic limitation specified in the Chinese code, and meets code requirements under major earthquakes. From the test results some suggestions are provided that could contribute favorable effect on the seismic behavior and the displacement of the building.     

Torsional dynamic response of a large‐diameter pipe pile in viscoelastic saturated soil

An analytical solution is developed in this paper to investigate the dynamic response of a large‐diameter end‐bearing pipe pile subjected to torsional loading in viscoelastic saturated soil. The wave propagation in saturated soil and pile are simulated by Biot's two‐phased linear theory and one‐dimensional elastic theory, respectively. The dynamic equilibrium equations of the outer soil, inner soil, and pile are established. The solutions for the outer and inner soils in frequency domain are obtained by Laplace transform technique and the separation of variables method. Then, the dynamic response of the pile is obtained on the basis of the perfect contacts between the pile and the outer soil as well as the inner soil. The results in this paper are compared with that of a solid pile in elastic saturated soil to verify the validity of the solution. Furthermore, the solution in this paper is compared with the classic plane strain solution to verify the solution further and check the accuracy of the plane strain solution. Numerical results are presented to analyze the vibration characteristics and illustrate the effect of the soil parameters and the geometry size of the pile on the complex impedance and velocity admittance of the pile head. Finally, the displacement of the soil at different depth and frequency is analyzed. Copyright © 2014 John Wiley & Sons, Ltd.     

Displacement analytical prediction of shallow tunnel based on unified displacement function under slope boundary

For slope condition of ground surface, the asymmetrical deformation about the vertical center line and the horizontal center line of the tunnel cross section can be formed. A unified displacement function expressed by the Fourier series is presented to express the asymmetrical deformation of the tunnel cross section. Five basic deformation modes corresponding to the expansion order 2 are a complete deformation mode to reflect deformation behaviors of the tunnel cross section under slope boundary. Such this complete displacement mode is implemented into the complex variable solution for analytically predicting tunneling-induced ground deformation under slope boundary. All of these analytical solutions are verified by good agreements of the comparison between the analytical solutions and finite element method results. A parameter study is carried out to investigate the influence of deformation modes of the tunnel cross section, geometrical conditions of the tunnel and the slope angle, and “Buoyancy effect” on the displacement field. Finally, the proposed method is consistent with measured data of the Hejie tunnel in China qualitatively. The presented solution can provide a simplified indication for evaluating the ground deformation under slope condition of ground surface.     

Phase equilibria modelling and LASS monazite petrochronology: P–T–t constraints on the evolution of the Priest River core complex,northern Idaho

Phase equilibria modelling, laser‐ablation split‐stream (LASS)‐ICP‐MS petrochronology and garnet trace‐element geochemistry are integrated to constrain the P–T–t history of the footwall of the Priest River metamorphic core complex, northern Idaho. Metapelitic, migmatitic gneisses of the Hauser Lake Gneiss contain the peak assemblage garnet + sillimanite + biotite ± muscovite + plagioclase + K‐feldspar ± rutile ± ilmenite + quartz. Interpreted P–T paths predict maximum pressures and peak metamorphic temperatures of ~9.6–10.3 kbar and ~785–790 °C. Monazite and xenotime ²⁰⁸Pb/²³²Th dates from porphyroblast inclusions indicate that metamorphism occurred at c. 74–54 Ma. Dates from HREE‐depleted monazite formed during prograde growth constrain peak metamorphism at c. 64 Ma near the centre of the complex, while dates from HREE‐enriched monazite constrain the timing of garnet breakdown during near‐isothermal decompression at c. 60–57 Ma. Near‐isothermal decompression to ~5.0–4.4 kbar was followed by cooling and further decompression. The youngest, HREE‐enriched monazite records leucosome crystallization at mid‐crustal levels c. 54–44 Ma. The northernmost sample records regional metamorphism during the emplacement of the Selkirk igneous complex (c. 94–81 Ma), Cretaceous–Tertiary metamorphism and limited Eocene exhumation. Similarities between the Priest River complex and other complexes of the northern North American Cordillera suggest shared regional metamorphic and exhumation histories; however, in contrast to complexes to the north, the Priest River contains less partial melt and no evidence for diapiric exhumation. Improved constraints on metamorphism, deformation, anatexis and exhumation provide greater insight into the initiation and evolution of metamorphic core complexes in the northern Cordillera, and in similar tectonic settings elsewhere.     

极化干涉SAR森林树高提取算法的对比分析

在对极化干涉SAR森林树高反演的DEM差值算法、相干相位-幅度综合反演算法进行分析的基础上,对基于极化干涉相干优化方法的改进算法进行了探讨。利用黑龙江大兴安岭地区的一对ALOS全极化干涉SAR数据进行实验,并对比分析各算法的反演结果。结果表明,在使用改进的算法进行森林树高反演时可以获取精度较高的反演结果,并且在一定程度上提高了森林树高反演的稳定性,为森林树高反演工作的业务化运行提供一定的依据。     

Hydrothermal frictional strengths of rock and mineral samples relevant to the creeping section of the San Andreas Fault

We compare frictional strengths in the temperature range 25–250 °C of fault gouge from SAFOD (CDZ and SDZ) with quartzofeldspathic wall rocks typical of the central creeping section of the San Andreas Fault (Great Valley sequence and Franciscan Complex). The Great Valley and Franciscan samples have coefficients of friction, μ > 0.35 at all experimental conditions. Strength is unchanged between 25° and 150 °C, but μ increases at higher temperatures, exceeding 0.50 at 250 °C. Both samples are velocity strengthening at room temperature but show velocity-weakening behavior beginning at 150 °C and stick-slip motion at 250 °C. These rocks, therefore, have the potential for unstable seismic slip at depth. The CDZ gouge, with a high saponite content, is weak (μ = 0.09–0.17) and velocity strengthening in all experiments, and μ decreases at temperatures above 150 °C. Behavior of the SDZ is intermediate between the CDZ and wall rocks: μ < 0.2 and does not vary with temperature. Although saponite is probably not stable at depths greater than ∼3 km, substitution of the frictionally similar minerals talc and Mg-rich chlorite for saponite at higher temperatures could potentially extend the range of low strength and stable slip down to the base of the seismogenic zone.     

冀北中低级变质表壳岩的年代学特征及其对华北克拉通构造演化的约束

华北克拉通在新太古代末期发生克拉通化,形成了现今规模的古陆,大量的太古宙岩石均经历了~2500Ma左右的区域高级变质作用(高角闪岩相-麻粒岩相)。而华北克拉通北部冀北地区出露一套中低级变质(绿片岩相-角闪岩相)的火山-沉积岩系,主要包括胡麻营地区红旗营子表壳岩和大阴山地区单塔子表壳岩中变质程度较低的部分。胡麻营地区红旗营子表壳岩系主要岩石组合为变基性火山岩、绿帘角闪岩、斜长角闪岩、含石榴石斜长角闪岩、角闪斜长片麻岩、黑云斜长片麻岩、黑云角闪斜长片麻岩、黑云二长片麻岩、石英片岩、磁铁石英岩等,SIMS锆石U-Pb定年结果表明斜长角闪岩形成于2486±18Ma(MSWD=1.4),而黑云斜长片麻岩形成于2507±37Ma(MSWD=2.0)。大阴山地区单塔子中低级变质表壳岩系主要由浅变质火山岩、云母石英片岩、斜长角闪岩、磁铁石英岩和大理岩等组成,SHRIMP锆石U-Pb定年结果显示,浅变质火山岩中的变玄武岩形成于2490±19Ma(MSWD=2.0),而变英安岩形成于2502±8Ma(MSWD=0.83)。因此,冀北中低级变质的表壳岩系主要形成于新太古代末期,形成年龄为2507~2486Ma;结合冀东青龙地区新太古代末期(2511~2503Ma)的浅变质火山-沉积岩系(青龙表壳岩),我们认为新太古代末期,中低级变质表壳岩系广泛分布于华北克拉通的核部和边缘地区,此套岩系覆盖在太古宙高级变质杂岩之上,代表华北克拉通化之后的稳定盖层,是克拉通化的主要标志之一。     

我国砂岩型铀矿成矿理论的创新和发展

简述了从国外到国内的砂岩型铀矿概况及成矿理论研究的发展,归纳出了我国砂岩型铀矿的"叠合复成因氧化-还原成矿理论",并就"预富集"、"板状矿体成因"、"深部油气作用"、"可地浸概念"、"大砂体"等问题进行了粗浅的讨论。     

低固相冲洗液在赣南再里地区的应用研究

钻进过程中,孔壁的稳定性和冲洗液的渗漏是影响钻进效率和钻孔质量的重要因素。孔内情况越复杂,施工周期越长,对冲洗液性能的要求也越高。赣南再里地区施工区构造发育复杂,地层中存在大量的松散、胶结性差的砂岩以及高岭土、绿泥石等水敏性地层,钻探施工钻孔容易缩径,孔壁稳定性差,极易出现剥落、掉块、坍塌等现象,试验采用了低固相不分散冲洗液,取得了良好的钻进效果。     

西藏拉萨地体西北部革吉地区两期早白垩世岩浆作用——锆石U-Pb年龄、Hf同位素和地球化学特征

邦巴岩体位于拉萨地块西部革吉地区,由主体花岗岩、花岗闪长岩、闪长质包体及一系列近平行、南北向展布的花岗斑岩脉体组成。野外地质调查和LA-MC-ICP-MS锆石U-Pb定年表明,革吉地区白垩纪的两期岩浆活动分别发生在131~132Ma和127Ma。早期岩浆作用形成主体花岗岩、花岗闪长岩及闪长质包体,具有以下特征:(1)明显富集K、Cs等大离子亲石元素,亏损Nb、Ti、Zr等高场强元素;(2)具有明显的负Eu异常(Eu/Eu*=0.49~0.61)及负Ce异常;(3)具负εHf(t)值(-3.2~-0.3)及古老的地壳模式年龄(1.210~1.399Ga);(4)初始Sr同位素比值为0.70424~0.71472,εHf(t)值为-5.70~-5.54。晚期岩浆作用形成花岗斑岩脉体,具有以下特征:(1)富集K、Cs等大离子亲石元素,强烈亏损Nb、Ta、Ti等高场强元素;(2)基本不具有负Eu异常或具有轻微的负Eu异常(Eu/Eu*=0.74~0.87);(3)具有更老的Hf同位素地壳模式年龄(1.226~1.576Ga)及更负的大范围变化的εHf(t)值(-6.1~-0.7)。晚期岩浆作用锆饱和温度(777~796℃)及轻稀土元素不饱和温度(794~812℃)均高于早期岩浆的锆饱和温度(661~762℃)及轻稀土元素不饱和温度(750~769℃)。上述特征表明,两期岩浆作用均为中拉萨地块古老基底部分与地幔物质混染部分熔融的产物,随着岩浆作用的持续进行,岩浆中的古老地壳组分增加,熔体温度也增加,可能与南向俯冲的班公-怒江洋壳回转驱动的地幔岩浆活动向北迁移有关。