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71.
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Yang Yunpeng Chen Guan Meng Xingmin Bian Shiqiang Chong Yan Shi Wei Jiang Wanyu Jin Jiacheng Li Chen Mu Xinliang Yue Dongxia 《Landslides》2022,19(4):789-808
Landslides - Determining the premonitory and dynamic characteristics of landslide dam failures can provide an early warning as well the identification of the evolution of the failure process, and... 相似文献
73.
Zhang Jin-Zhang Zhang Dong-Ming Huang Hong-Wei Phoon Kok Kwang Tang Chong Li Gang 《Acta Geotechnica》2022,17(4):1129-1145
Acta Geotechnica - The scale of fluctuation (SOF) is the critical parameter to describe the soil spatial variability, which significantly influences the embedded geostructures. Due to the limited... 相似文献
74.
Pile foundation is one of the most commonly used and suitable foundations to support transmission line structure, especially in seasonally frozen soil regions and permafrost regions. Axial compression is the controlling condition in the design of foundations for such structures as bridges and buildings, while uplift and overturning will control the design of transmission line structure foundations. This paper presents an extensive overview of previous studies including experimental (e. g., laboratory model test and full-scale field load test), analytical/theoretical (e. g., limit equilibrium and limit analysis based on plasticity)and numerical(e. g., finite difference and finite element methods). The review indicates that study on the uplift behavior of pile foundation in frozen soil is relatively limited, particularly in the case of combined effect of axial uplift and lateral loading. Interaction between pile and frozen soil and mechanism of load transfer along the pile shaft and around the pile tip still remain unclear. Therefore, this paper implements finite difference analysis within FLAC3D to investigate the behavior of pile foundation in frozen silty clay and gravelly sand under axial uplift behavior and the effect of ground condition and lateral loading on the uplift behavior. Because of the axisymmetric condition of the problem studied, only half of the model is simulated. The chosen domain of the medium is discretized into a set of quadrilateral elements and the pile is discretized by the cylinder element. The interaction between the soil and pile is considered according to interface elements. Mohr-Coulomb criterion is adopted to model the soil behavior (perfectly elastic-plastic), while the pile is simply considered as a rigid body. The soil parameters such as Young’s modulus, cohesion and internal friction angle used for numerical analyses are determined by laboratory tests and estimated according to the empirical correlations with in-situ tests. The present numerical modeling is verified with the results from field loading tests on pile foundations in Qinghai-Tibet ±550 kV transmission line project. On this basis, parametric studies are carried out to uncover the behavior of pile in frozen soil. It is observed that pullout is the dominant failure mechanism of pile and the uplift load-displacement curve clearly exhibits an asymptote, consisting of initially linear elastic, nonlinear transition, and finally linear regions. These results are consistent with the observations in a few previous studies. In addition, larger uplift capacity of pile foundation in freezing period and gravelly sand is gained (about 20%). Lateral loading increases the deflection and therefore, decreases the uplift capacity of pile foundation. For the convenience of using the results obtained in practice, the values of uplift factor for pile foundation in silty clay and gravelly sand are provided. Finally, it should be noted that the method used, and the results obtained in the current work could be useful for engineers and designers, at least providing them some qualitative evidence for pile design in seasonally frozen soil regions and permafrost regions. This is important and necessary to ensure the safety of construction in such regions. Meanwhile, numerical analyses in the current work can be a benchmark example for subsequent research studies. © 2022 Science Press (China). 相似文献
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文章根据西藏古堆—隆子地区Sb,Pb,Zn化探元素品位分析结果,结合区域地质资料,基于分形几何学的理论基础,对研究区Sb,Pb,Zn的分布规律进行了定量研究。结果表明,4个研究区Sb,Pb都具有多重分维的性质,且与矿化有关的分维值D2ⅡD2Ⅲ,同一研究区同一元素的各组分维值差距较大,Ⅲ区和Ⅳ区的Zn只有一个维数值,说明典型矿床发育的地区成矿元素具有多重的分维结构和低分维值D2,基于此理论成功验证了恰嘎研究区具有寻找锑矿前景。通过研究Sb,Pb,Zn的分形特征,揭示出化探元素的分维结构和分维值的大小与矿化程度有关,并为找矿勘查工作提供一定的地质依据。 相似文献
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利用6 h一次、水平分辨率为0.25°×0.25°的ERA-Interim再分析资料,对1979—2016年生成于四川盆地的西南涡的发生和发展进行统计分析。结果表明:四川盆地低涡集中生成于盆地内;在6月生成最多,7月发展最强;按移动情况不同可将其分为5类:东移型、东北移型、东南移型、西移型和少动型;东移型、东南移型、少动型低涡生成个数的峰值在6月,东北移型和西移型低涡生成个数的峰值在7月。夏季5类长生命史四川盆地低涡的结构和降水合成场表明:从发展强度看,东北移型最强,少动型最弱。从成熟期垂直结构看,除西移型外,低涡均随高度向西北或向西倾斜,在对流层低层为冷性结构,中层为暖性结构;东移型、东北移型、西移型低涡的正涡度区在垂直方向伸展更高;除东南移型、西移型低涡的强上升区与其中心重合外,其余类型位于其中心东侧。从降水特征看,除西移型外,其余类型低涡的降水中心均位于其移动路径东侧或东北侧,其中东北移型低涡成熟期6 h累计降水量最大。四川盆地低涡的强上升区、相对湿度大值区、位于对流层低层和中层的辐合辐散中心与降水所在位置有很好的对应关系,各物理量场相互作用共同促进低涡发展。 相似文献
78.
With the aid of a normal form of a family of measure-preserving mappings in dimension 3, which is deduced in this paper, we prove that there are periodically invariant curves which survive the nonlinear perturbations in the generic case. 相似文献
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