Environmental Effect Caused by Over-exploitation of Deep Groundwater in North China

Based on the formation and development analysis of the environmental geological disaster of land subsidence, earth fissures and other geological disasters in the North China, it showed these disasters caused a very serious problem in some areas of the North China, such as the deep groundwater exploitation cone, which is accumulated with great damage and loss and is hard to be controlled, therefore, great attention should be paid. It is considered that the formation of the deep groundwater cone is the root of various geological environmental problems, and the groundwater cone recovery is the key to solve other environmental problems     

Analysis of resistivity data obtained from cone penetrometer in contaminated soil layers

In horizontally layered soils of different electrical properties, electrical potential distribution becomes complex and the obtained resistivity data may be limited in reflecting the actual soil profile. Thus the objective of this study was to identify the factors that affect resistivity measurement on the cone penetrometer and further investigate the sensitivity of measured resistivity to different types and concentrations of contaminants at the subsurface level. First, a theoretical resistivity equation was derived to provide a means of computing the geometric factor. The effective volume of measurement on the cone penetrometer was investigated and laboratory soil box tests verified the dominance of partially high resistivity regions within the effective volume of measurement over the apparent resistivity. Such effect was found to lead to possible discrepancies between the recorded resistivity data and the actual depth of measurement. Measurements on contaminated soil layers indicated that resistivity cones are efffective in delineating inorganic contaminants in soils of high water contents, and detecting NAPLs floating above the groundwater table provided that soils adjacent to the plume are not dry of water. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Evaluation of Liquefaction Potential Index Along Western Coast of South Korea Using SPT and CPT

For South Korea, liquefaction potential along the western coast has not been widely assessed because South Korea is considered to be a low seismic hazard. However, recent earthquake events and historical records indicate that the seismic hazard of South Korea should not be ignored. Moreover, as artificial fills are extensively used along the western coast for development, liquefaction evaluation of the soils in this area is necessary. In this paper, we present: (1) the seismic characteristics of the study area; (2) procedures for evaluating liquefaction potential, focusing on the liquefaction potential index (LPI) approach; and (3) LPI distributions at several representative locations along the western coast of South Korea under various seismic scenarios. The liquefaction potential index represents the liquefaction potential over the upper 20 m of a boring or sounding. Using cone penetration test (CPT) and standard penetration test (SPT) data from two coastal sites, we compare and discuss CPT-based and SPT-based LPI values, particularly values computed in nonplastic, silt-rich soils. In these soils, it appears that the CPT yields lower liquefaction resistance, resulting in large LPI values. Finally, discussion and suggestions are provided for CPT- and SPT-based liquefaction assessment of low plasticity and high fines content soils.     

Comparison of vane shear and fall cone strengths of soft marine clay

A total of 1,014 measures of sediment shear strengths were measured by means of miniature vane shear and fall cone tests on five gravity cores collected in Eckernfo‐erde Bay, Baltic Sea. Paired t test was used to compare the shear strengths measured by the two methods. It was found that fall cone strength calculated with Wood's K₆₀value (0.29) overestimates the vane shear strength by 0.15 kPa (a = 0.001) and the sample mean of the fall cone strength is 4.1% higher than the mean of the vane shear strength. However, fall cone strength calculated with Hansbo's K₆₀ value (0.24) underestimates the vane shear strength by 0.88 kPa (a = 0.001), and the sample mean of the fall cone strength is 13.8% less than the mean of the vane shear strength. Both calculated fall cone strengths are significantly different from the vane shear strength, with a p value of less than 0.001. Regression analysis of the Echernfoerde Bay data indicates that a new K₆₀ value is 0.275 with a confidence interval (a = 0.01) from 0.2704 to 0.2786. Paired t test shows that there is no significant difference between miniature vane shear and fall cone tests for these samples if the fall cone strength is calculated with K₆₀ = 0.275.     

福建永安下白垩统坂头组Elatides属雌球果化石 研究

对采自福建永安市下白垩统坂头组的似纵属Elatides雌球果化石进行了宏观形态和角质层特征的研究,这些球果均单独保存,较小,果鳞较多,螺旋状紧密排列,顶端收缩呈尖刺状,与Elatides的特征相符。根据球果的形态、果鳞及其球果中轴的特征,将这些球果鉴定为3个种,即永安似纵(新种)Elatides yonganensis Dai et Sun, sp. nov.、弯叶似纵(相似种)Elatides cf. curvifolius及一未定种Elatides sp.。其中重点描述了新种E. yonganensis的形态特征,该球果以中轴呈波状,果鳞顶端较长、较尖,腹面具有锯齿状的膜质小舌,每一果鳞具有大概5枚种子而区别于以前报道的任一已知种。同时对中国的Elatides化石记录进行了收集整理,Elatides属的球果化石在福建永安坂头组的发现表明其分布区可达25°N,丰富了该属植物的化石记录并扩大了其分布范围。     

不同重力场下静力触探试验离散元数值分析

采用离散元商业软件PFC2D对7种重力场下静力触探试验进行了对比分析试验,以研究高、低重力场下静力触探试验的异同点。数值试验结果表明：不同重力场下土体受静力触探贯入主要影响区域不同,低重力场下主要是上部土体受到影响,高重力场下主要是下部土体受到影响;归一化贯入阻力的最大值和稳定值、归一化球应力和偏应力的最大值均与重力加速度的倒数呈线性关系,均随重力加速度倒数的增加而增大;土体经历了明显的加载、卸载过程,重力加速度越小,加载、卸载现象越明显,同一重力加速度下上部土体加载、卸载程度大于下部土体。     

TJ-1模拟月壤承载特性的现场试验研究

采用TJ-1模拟月壤作为试验材料,通过静力触探、静载荷试验的对比分析,探讨适合月壤承载力计算的经验公式,以期为未来载人登月时宇航员和着陆器登陆可能涉及到有关月面承载能力的问题提供必要的参考。首先,使用近255 t TJ-1模拟月壤人工制备出13 m×12 m×1.2 m试验用地基,后在试验地基均匀布置6个静力触探测点和2个静载荷试验测点进行测试。针对太沙基承载力计算半经验公式以及规范和国内外学者提出的12个适合中密实砂土静力触探承载力计算的经验公式,对试验结果进行探讨。发现直接运用太沙基提出的半经验公式计算月壤承载力结果明显偏小,而由联合试验小组提出的经验公式 能够用来近似计算月壤地基承载力。计算结果表明,该经验公式在计算承载力时能够与静载荷试验值较好的吻合。     

在锥度量型空间上4个映射的公共不动点定理

为了强化理论知识的应用,利用锥度量型空间中自映射,讨论常数K的范围得出公共不动点的存在性和唯一性问题,证明了一个新的公共不动点定理.把锥度量型空间看作是锥度量空间的推广,在空间里,证明了4个映射的某些不动点定理.所得结论延伸和推广了文献中熟悉的相容性的一些论断.所有结论都在一致锥的背景下得到证明,且不需要假设函数的连续性.文章结果改进和发展了Aleksandar S Cvetkovi的结果.     

非线性四阶四点边值问题的正解

利用锥不动点定理,并结合Green函数性质,证明一类四阶四点边值问题的正解的存在性.     

中国荔波锥状喀斯特世界自然遗产价值全球对比分析

研究世界自然遗产地价值,对遗产地本身以及其他类似区域的可持续发展有重要意义。基于系统论思想,将"中国南方喀斯特"第一批三处遗产地中的荔波锥状喀斯特置于全球视角,选取相似的、具有代表性的区域,结合世界遗产第八条有关地质地貌特征与演化历史等方面的评价标准,进行全球对比分析,揭示其全球显著价值。研究表明:荔波锥状喀斯特具有更为独特的演化环境与更为复杂的地质演化过程;更有典型的锥状喀斯特单体形态与较为齐全的地貌组合类型,更有罕见的锥状喀斯特森林生态系统和生命记录。荔波锥状喀斯特是反映地球热带-亚热带锥状喀斯特演化历史主要阶段的典型范例,极具代表中国南方喀斯特的世界遗产价值。