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901.
Characteristics of soil erosion change along a long slope in the gentle hilly areas in black soil region in Northeast China are discussed. A simplified slope model based on seg-ments was used to analyze the runoff data and soil erosion data observed between 2003 and 2004 over 10 field plots with different slope length in Heshan Farm, Heilongjiang Province. We found that soil erosion rate over long slopes in the black soil region changed alternatively along the slope and creates alternative zones of intensive erosion and week erosion.The exact place of each zone is different for different rainfall conditions. In a year with less and mild precipitation, rill cannot happen within the top 50 m, while in a year with large and inten-sive precipitation, rill can be formed starting even at 15 m from the top of the slope. 相似文献
902.
903.
We describe in detail the deformation structures and textures of a large-scale landslide body that developed in the Betto-dani
Valley in northern central Japan. We studied the shape-preferred orientation of clasts and clay flakes and the development
of internal shear planes within the slip zone of the landslide. The slip has an average rate of 5–10 cm/year under the overburden
pressure of approximately 1.6 MPa; these values are similar to those of the proto-decollement zone of the Nankai accretionary
prism in SW Japan. The anisotropy of magnetic susceptibility of samples obtained from the slip zone reveals that the long
axes of clay flakes define an imbricate structure. The slip was due to a long-term periodical creep, which occurs during the
thaw seasons with an average slip rate of 0.16–0.32 μm/min. During the creep, the long axes of grains including clay flakes
in the slip zone are developed from parallel to perpendicular to the slip direction. The observed textures provide a clue
to elucidate the deformation textures and process in the decollement zone of the Nankai prism. 相似文献
904.
Very soft organic harbour mud is increasingly used as a filling and construction material in harbour construction and reorganization.
The undrained shear strength of such soft sediments is the critical geotechnical soil parameter with regard to any specific
construction design. Field and laboratory vane shear testing is a standard method to quickly determine this important parameter.
So far, the effect of rod friction on vane shear tests in very soft organic soils is unclear. In this study we present results
from laboratory experiments on harbour mud from a construction site in northern Germany. Relations among vane and rod geometry,
penetration depth, water content, rod friction and undrained shear strength are derived. Based on these relations the influence
of rod friction on vane shear test results is investigated. The results indicate that field and laboratory vane shear test
measurements may be significantly influenced by rod friction. Methods are proposed to correct for the rod influence, which
is shown to increase with rising water contents. 相似文献
905.
个旧老-卡岩体接触-凹陷带锡-铜多金属矿地质特征及成因分析 总被引:3,自引:0,他引:3
个旧老—卡岩体接触—凹陷带是个旧矿集区最重要的锡-铜多金属成矿构造带,该带中锡、铜矿产资源十分丰富。通过对凹陷带内矿体地质特征、围岩地层含矿性、微量元素、稀土元素、稳定同位素等的研究,结合大地构造环境,结果认为,凹陷带矿体是多种成矿物质来源,经历多种地质作用、多个大地构造演化阶段的多因复成矿床,接触-凹陷带锡-铜矿体形成主要与燕山中晚期花岗岩岩浆作用有关,其次与印支期海底火山-沉积与海底(火山)喷流-热水沉积成矿作用有关。 相似文献
906.
This paper focuses on the influence of the initial void ratio on the evolution of the passive earth pressure and the formation
of shear zones in a dry sand body behind a retaining wall. For the numerical simulation a rigid and very rough retaining wall
undergoing a horizontal translation against the backfill is considered. The essential mechanical properties of cohesionless
granular soil are described with a micro-polar hypoplastic model which takes into account stresses and couple stresses, pressure
dependent limit void ratios and the mean grain size as a characteristic length. Numerical investigations are carried out with
an initially medium dense and initially loose sand using a homogeneous and random distribution of the initial void ratio.
The geometry of calculated shear zones is discussed and compared with a corresponding laboratory model test. 相似文献
907.
Branka Trček 《Environmental Geology》2007,51(5):761-765
The role of an epikarst zone in the karst aquifer hydraulic behaviour was brought into focus in our studies referring to the
catchment area of the Hubelj spring (SW Slovenia). This study points out the significance of effects of the fast preferential
flow—epiflow, which is the main factor controlling solute/contaminant transport towards the aquifer saturated zone. The so-called
epikarstic hypothesis is verified on the basis of the most significant research results that are supported by the most important
findings from the literature. 相似文献
908.
Analysis of kinematic seismic response of tapered piles 总被引:2,自引:0,他引:2
Mahmoud Ghazavi 《Geotechnical and Geological Engineering》2007,25(1):37-44
In the present work, a two-phase analysis is used to assess the lateral movement of a tapered pile due to kinematic seismic
loading resulted from earthquakes. First, the free-field horizontal displacement of the ground due to earthquake is estimated
using available theory of wave propagation. Second, these estimated soil movements are imposed on the taper pile in a closed-form
solution to compute the pile response. The governing differential equation for an arbitrary pile segment is obtained, which
includes the free-field horizontal movement estimated from the first phase. The equation is solved explicitly to obtain the
horizontal deflection. Parametric studies show that tapered piles tend to be more flexible than uniform piles of the same
volume and length under earthquake loading, which is soundly interesting. 相似文献
909.
关于迪庆香格里拉发展旅游产业集群的探讨 总被引:1,自引:0,他引:1
当代的国际经济竞争是产业集群的竞争。产业集群现象的大量出现以及成功的发展实践,为欠发达地区实现跨越式发展提供了一条新的发展之路。旅游业的综合性显示着产业集群的优势条件,旅游产业集群化发展是区域旅游业竞争力提升的有效模式。近几年来中国许多地方的旅游业呈现出产业集群化发展趋势,展现了旅游产业集群在区域竞争中的优势。通过运用波特的钻石体系分析了在迪庆香格里拉这样的欠发达地区发展旅游产业集群的有利条件以及面临的问题,并由此提出了香格里拉发展旅游产业集群的对策。 相似文献
910.