Empirical Formula of Shear Strength of Rock Fractures Based on 3D Morphology Parameters

The prime objective of this work is to provide a reference to predict the peak shear strength of rock fractures. The paper studied some shear properties of rock fractures and proposed an empirical formula for the peak shear strength of rock fractures based on 3D morphology parameters. The rock fractures were induced in cylindrical sandstone and marble specimens by means of indirect tension. A rock direct shear apparatus (RDS-200) was adopted to conduct direct shear tests on five groups of rock fractures under different levels of normal load. Before the direct shear test, 3D morphology parameters of rock fracture surfaces were obtained using a 3D optical scanner. By analyses of direct shear test data, the relationships between peak shear strength, peak shear displacement, peak dilatancy angle, residual friction coefficient and peak normal stress were found. According to the evolution trends of peak shear strength and peak dilatancy angle along with the normal stress, an empirical formula was proposed to predict the peak shear strength of rock fractures in both sliding and cutting failure modes considering the 3D morphology parameters of rock fracture surfaces. The empirical formula could be commonly used for different types (sandstone and marble) and grain sizes (powder-grained, fine-grained, medium-grained and coarse-grained) of rock fractures.     

中国荒漠植物-土壤系统生态化学计量学研究进展

荒漠生态系统是中国陆地生态系统的重要组成部分,具有独特的结构和功能.生态化学计量学重点关注C、N、P元素比例及权衡关系,已成为揭示生态系统养分循环及其限制等生态过程的有力工具.植物自身体现出对养分元素的调控能力和对环境变化的响应及适应性,土壤C∶N∶P可表征土壤养分供应能力和储量变化,植物-土壤系统中N、P的养分循环关...     

新疆东准噶尔锡矿北花岗斑岩的锆石LA-ICP-MS U-Pb测年

对东准噶尔锡矿北花岗斑岩进行锆石LA-ICP-MS U-Pb测年,获得206Pb/238U加权平均年龄为(281±10)Ma,MSWD=9.3,206Pb/238U-207Pb/235U谐和曲线图中下交点年龄为(278±11)Ma,MSWD=7.5,两者在误差范围内完全一致,时代属于早二叠世。结果表明,锡矿北花岗斑岩形成的时代属于东准噶尔后碰撞深成岩浆活动的范围(330～265Ma),晚于东准噶尔乌伦古河碱性花岗岩和卡拉麦里碱性花岗岩的形成时代（300Ma左右）,以花岗斑岩为代表的晚古生代岩浆侵入活动延续到早二叠世晚期。     

Effects of initial soil water content and saturated hydraulic conductivity variability on small watershed runoff simulation using LISEM

Abstract

Soil water content (θ) and saturated hydraulic conductivity (K_s) vary in space. The objective of this study was to examine the effects of initial soil water content (θ_i) and K_s variability on runoff simulations using the LImburg Soil Erosion Model (LISEM) in a small watershed in the Chinese Loess Plateau, based on model parameters derived from intensive measurements. The results showed that the total discharge (TD) and peak discharge (PD) were underestimated when the variability of θ_i and K_s was partially considered or completely ignored compared with those when the variability was fully considered. Time to peak (TP) was less affected by the spatial variability compared to TD and PD. Except for TP in some cases, significant differences were found in all hydrological variables (TD, PD and TP) between the cases in which spatial variability of θ_i or K_s was fully considered and those in which spatial variability was partially considered or completely ignored. Furthermore, runoff simulations were affected more strongly by K_s variability than by θ_i variability. The degree of spatial variability influences on runoff simulations was related to the rainfall pattern and θ_i. Greater rainfall depth and instantaneous rainfall intensity corresponded to a smaller influence of the spatial variability. Stronger effects of the θ_i variability on runoff simulation were found in wetter soils, while stronger effects of the K_s variability were found in drier soils. For accurate runoff simulation, the θ_i variability can be completely ignored in cases of a 1-h duration storm with a return period greater than 10 years, while K_s variability should be fully considered even in the case of a 1-h duration storm with a return period of 20 years.

Editor D. Koutsoyiannis; Associate editor A. Fiori     

Plant Species Richness Increased Belowground Plant Biomass and Substrate Nitrogen Removal in a Constructed Wetland

The effects of plant species richness on both above‐ and belowground plant biomass, plant nitrogen (N) pool size, and substrate N concentrations were studied in a full‐scale subsurface vertical‐flow constructed wetland (CW). Results showed that (i) plant species richness increased belowground plant biomass and its N pool size but had no effect on aboveground plant biomass and its N pool size; (ii) plant species richness increased substrate N removal, especially ammonium N removal; and (iii) plant species richness had no effect on plant N use efficiency, suggesting that the N pool size increased with increasing plant species richness. More N accumulation could be removed through harvesting plant biomass. We concluded that the N removal performance of the CW improved by plant species richness through increasing belowground biomass and relevant N pool size.     

含富锂(钾)卤水断陷盆地的深部构造特征: 以中国华南吉泰盆地为例

中国华南吉泰盆地在白垩纪?古近纪发育大量蒸发岩,其中含富锂卤水矿床,由于盆地深部构造特征认识不清,导致富锂卤水矿勘查评价明显滞后.基于盆地东北部泰和坳陷二维地震数据和钻孔资料,经过精细保幅处理和综合构造解释,总结了含富锂卤水矿断陷盆地的深部构造特征.地震剖面和构造属性表明,盆地深部发育错断白垩系的NE-SW走向、NW倾...     

ArcGIS三维分析技术在潜在滑坡体预测中的应用

以贵州省六盘水市水城县大河镇一个潜在滑坡体为例,利用遥感影像（RS）、地理信息系统（GIS）、遥感图像处理（ENVI）和三维分析（ArcGIS）等技术,完成了对该地质体的高分辨率遥感影像和DEM信息数据的生成处理。并采用ArcGIS三维分析方法技术,实现了对所预测的潜在滑坡体三维的立体可视化成图及其表面积、体积的概略计...     

泌阳凹陷毕店地区油藏特征浅析

泌阳凹陷毕店地区经过三十多年的勘探,一直没有取得实质性的突破。2005年以来对该区三维地震资料重新处理与解释攻关,基本具备了精细勘探的物质基础。毕店地区主体已发现的油气藏类型以断层+岩性油气藏为主。通过应用系统的研究思路,以现代石油地质理论为指导,初步探讨毕店地区油藏分布特征与油气成藏的控制作用。     

原子吸收分光光度法快速测定红土镍矿中镍

试样经烘干处理后,利用酸溶法或碱融法制备稳定的分析溶液,然后利用原子吸收分光光度计于波长232.0nm处,随同标准曲线测量镍含量,此方法简单、快捷,所选分析线干扰小、灵敏度高,稳定性和准确度均满足要求。