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排序方式: 共有3121条查询结果,搜索用时 296 毫秒
991.
甘肃省舟曲县"8.8"特大山洪泥石流灾害与气象成因分析及其应对建议 总被引:1,自引:0,他引:1
通过调查舟曲地质灾害历史资料.分析降雨与地质灾害的相关性,发现地质灾害与灾害前1~3 h累积降水量、月平均降水量和月暴雨频数明显正相关.然后分析舟曲"8.8"特大山洪泥石流的气象和降水成因.在此基础上,提出舟曲地质灾害的防治措施. 相似文献
992.
Deep-seated cracked gas exploration was achieved great breakthrough in Es4L of the Minfeng area on the northern slope of the Dongying Sag. Carbon isotopic and molecular compositions studies revealed the characteristics of wet gas and a normal trend of carbon isotopic composition. Empirical cutoff points of δ13C2 and δ13C3 and light hydrocarbon compositions distinguished the cracking gas as sapropelic gas. Variations in i/nC5, i/nC4 and δ13C2 fur-ther confirmed that the gas was cracked from residual kerogen. Source characteristics indicated that the gas was de-rived from mature-highly mature source rocks of Es4 with kerogen type II being dominant mixed with some oil-cracking gas. Burial history modeling indicated that there were two hydrocarbon charging periods in Es4L reser-voirs. The first period refers to the Guantao-Minghuazhen stage dominated by oil charging, while the second period refers to the Minghuazhen stage and has been dominated by cracked gas charging till now. 相似文献
993.
黔南地区宾夕法尼亚亚纪逍遥阶礁相地层中腕足动物普遍发育,主要产长身贝类和石燕贝类。本文主要研究该区腕足动物与造礁生物叶状藻和Fomitchevella 珊瑚之间的生态关系。在叶状藻礁内,小个体腕足动物常附着在藻叶上营假漂浮生活; 但藻叶密集处,小个体腕足动物也难见,可能藻丛造成水流循环不畅使腕足动物难以获得充足的食料; 藻叶稀疏处,腕足动物个体加大,数量增加。在大型Fomitchevella 珊瑚格架礁内,腕足动物与Fomitchevella 之间不存在食物上的竞争。腕足动物介壳层为Fomitchevella 幼虫定殖提供了生物成因的硬质基底,在此基础之上发育了大型珊瑚礁。腕足动物在 Fomitchevella 进入统殖阶段由于生态空间受到局限而退居次要地位。 相似文献
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Field testing of erodibility of two landslide dams triggered by the 12 May Wenchuan earthquake 总被引:4,自引:3,他引:1
A strong earthquake of magnitude 8 in Richter scale, occurred in Sichuan Province, China on 12 May 2008, triggered about 257
landslide dams. The erodibility of fresh landslide deposits plays an important role in evaluating the initiation and development
of breaching of such landslide dams. In this research, field jet index tests were conducted shortly after the earthquake at
27 locations on the Hongshihe landslide dam and the Libaisi landslide dam. The purpose of these tests was to investigate the
erodibility of freshly deposited landslide soils. The landslide deposits are broadly graded. The bulk density increases and
the coefficient of erodibility decreases with the depth of deposition. The erodibility of the fresh landslide deposits falls
into a moderately resistant category and the fresh deposits are much more erodible than the native geomaterials before the
earthquake. The main factors that control soil erodibility are found to be grain-size distribution, void ratio, fines content,
and plasticity index. Particularly, the coefficient of erodibility decreases exponentially with the degree of compaction.
Two empirical equations are developed for estimating the coefficient of erodibility and critical erosive shear stress of the
freshly deposited landslide soils based on their basic soil properties. 相似文献
998.
Yu-Pin Lin Hone-Jay Chu Yu-Long Huang Bai-You Cheng Tsun-Kuo Chang 《Environmental Earth Sciences》2011,62(2):299-311
This study proposes the method of simulating spatial patterns and quantifying the uncertainty in multivariate distribution
of heavy metals (Cr, Cu, Ni, and Zn) by sequential indicator simulation (SIS) combined with conditional Latin hypercube sampling
(cLHS) in Changhua County, Taiwan. The cLHS is used for a sampling then for SIS mapping and assessing uncertainties of heavy
metal concentrations. The indicator variogram results indicate that the 700 cLHS samples replicate statistical multivariate
distribution and spatial structure of the 1,082 samples. Moreover, the SIS realizations based on 700 cLHS samples are more
conservative and reliable than those based on 1,082 samples for delineating soil contamination by all heavy metals with the
exception of Zn. Given adequate sampling, soil contamination simulation provides sufficient information for delineating contaminated
areas and planning environmental management. 相似文献
999.
Su-Chin Chen Kuang-Tsung Chang Shi-Hao Wang Jun-Yue Lin 《Environmental Earth Sciences》2011,62(1):197-206
This study investigates the performance of artificial materials used for erosion control on steep slopes under high rainfall
intensity. Soil samples were laid on a 300 × 100 cm platform inclined at either 35° or 45°, after which the soil was covered
with various materials and subjected to a rainfall intensity of 130 mm/h for an hour. A wooden-block net covered with a jute
net resulted in the greatest erosion resistance, providing 83% resistance at 35° and 76% at 45°. On the 35° slope, the artificial
materials showed relatively good erosion resistance. As the slope was raised to 45°, some of the materials did not attach
effectively to the soil surface. Thus, the runoff velocity increased and erosion became severe. For optimum erosion resistance,
the material used to protect soil must attach to the soil surface well and have structural properties, such as a high coverage
ratio to reduce the impact of rainfall on the soil and uniformly distributed transverse structures to reduce runoff energy
and trap soil. 相似文献
1000.