Tensionless–frictionless interaction of flexible annular foundation with a transversely isotropic multi‐layered half‐space          下载免费PDF全文

Morteza Eskandari‐Ghadi  Ghasem Gorji‐Bandpey  Azizollah Ardeshir‐Behrestaghi  Seyed Masoud Nabizadeh 《国际地质力学数值与分析法杂志》2015,39(2):155-174

A transversely isotropic multi‐layered half‐space, with axis of material symmetry perpendicular to the free surface, supports a flexible either annular or solid circle foundation. The contact area of the foundation and the half‐space is considered to be both frictionless and tensionless. The foundation is assumed to be affected by a vertical static axisymmetric load. Detailed analysis of the interaction of these two systems with different thickness of layers is the target of this paper. With the use of ring load Green's functions for both the foundation and the continuum half‐space, an integral equation accompanied with some inequalities is introduced to model the complex BVP. With the incorporation of ring‐shape FEM, we are capable of capturing both regular and singular solution smoothly. The validity of the combination of the analytical and numerical method is proved with comparing the results of this paper with a number of benchmark cases of both linear and nonlinear interaction of circular and annular foundation with half‐space. Some new illustrations are presented to portray the aspect of the anisotropy and layering of the half‐space. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

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

Changjie Zheng  Hanlong Liu  Xuanming Ding  Yaru Lv 《国际地质力学数值与分析法杂志》2014,38(16):1724-1743

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.  相似文献   

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

Fanchao Kong  Dechun Lu  Xiuli Du  Chenpeng Shen 《国际地质力学数值与分析法杂志》2019,43(1):183-211

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.  相似文献   

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

L. M. Stevens  J. A. Baldwin  J. M. Cottle  A. R. C. Kylander‐Clark 《Journal of Metamorphic Geology》2015,33(4):385-411

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.  相似文献   

Analytical solutions for advective–dispersive solute transport in double‐layered finite porous media     

Peter John Cleall 《国际地质力学数值与分析法杂志》2011,35(4):438-460

Analytical solutions for advection and dispersion of a conservative solute in a one‐dimensional double‐layered finite porous media are presented. The solutions are applicable to five scenarios that have various combinations of fixed concentration, fixed flux and zero concentration gradient conditions at the inlet and outlet boundaries that provide a wide number of options. Arbitrary initial solute concentration distributions throughout the media can be considered via explicit formulations or numerical integration. The analytical solutions presented have been verified against numerical solutions from a finite‐element‐based approach and an existing closed‐form solution for double‐layered media with an excellent correlation being found in both cases. A practical application pertaining to advective transport induced by consolidation of underlying sediment layers on contaminant movement within a capped contaminated sediment system is presented. Comparison of the calculated concentrations and fluxes with alternative approaches clearly illustrates the need to consider advection processes. Consideration of the different features of contaminant transport due to varying pore‐water velocity fields in primary consolidation and secondary consolidation stages is achieved via the use of non‐uniform initial concentration distributions within the proposed analytical solutions. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

极化干涉SAR森林树高提取算法的对比分析     

李帆  尚玉双  杨兆臣 《测绘与空间地理信息》2016,(1):94-96

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。  相似文献   

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

《Journal of Structural Geology》2016

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.  相似文献   

复杂地形城市多尺度气流对大气污染影响的研究进展     

李霞 《沙漠与绿洲气象(新疆气象)》2016,10(6):1-10

复杂地形城市一般建立在山地、丘陵、沿海地带。复杂地形下的大气污染传输、扩散机制是一个复杂的问题。本文依据城市地形地貌将复杂地形归类为河谷地形、三面环山临海地形、盆地地形、马蹄型地形和峡口地形。结合国内外对这五类地形下城市污染物传输扩散及污染形成机制的研究成果,介绍了不同地理位置、不同复杂地形城市多尺度气流相互或交替作用的特点及其对污染传输扩散的影响,期望能够为其它复杂地形城市污染形成机制研究和大气污染防治提供一些借鉴。  相似文献   

结合模平方的双树复小波变形监测数据滤波   总被引：1，自引：0，他引：1  

梁月吉  任超  庞光锋  蓝岚 《测绘科学》2016,41(6):23-27

针对变形监测数据的去噪问题,该文在分析离散小波变换去噪不足的基础上,提出了一种基于模平方的双树复小波变形监测数据滤波方法。该方法利用双树复小波变换的完全重构、近似平移不变性和较好的方向选择性等特点,通过最小尺度空间的小波系数得到噪声强度,并结合模平方处理法确定各层的阈值,经重构阈值处理后的各层小波系数即得到去噪后的信号;经算例,并与传统离散小波变换对比分析。结果表明:双树复小波变换的分解效果优于传统离散小波变换,能较好地表现出细节部分的频率信息,使变形信号的周期性变化特征更为明显。该方法去噪更彻底,进一步提高了消噪的精度和可靠性,可作为变形监测数据降噪处理的新方法。  相似文献   

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   总被引：1，自引：1，他引：0  

葛松胜  翟明国  李铁胜  彭澎  王浩铮  崔夏红 《岩石学报》2016,32(2):571-589

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。  相似文献