放养密度对大杂交鲟生长性能的影响及生理应答机制

为探讨放养密度对鱼类生长及生理应答机制的影响规律和作用,作者以大规格大杂交鲟(达氏鳇(Huso dauricus)♀×施氏鲟(Acipenser schrenckii)♂)为实验材料,研究了平均初始体质量约为243 g/尾,放养密度分别为6(SD1组)、9(SD2组)、12(SD3组)、15 kg/m3(SD4组)条件下,不同放养密度处理70 d后的实验鱼生长性能变化及生理应答机制。结果显示,放养密度对大杂交鲟肥满度影响不显著,SD2组鱼类具有最大的特定生长率和生长效率,随着放养密度增加,日增质量显著降低(P0.05),特定生长率和生长效率下降。测定了血液甲状腺素(T4)、三碘甲腺原氨酸(T3)和皮质醇水平变化,发现放养密度能引起大杂交鲟3个血液生理指标发生显著改变;随着养殖时间推移,T3和皮质醇浓度显著升高,T4浓度显著下降(P0.05)。这些结果说明神经内分泌活动的变化引起大杂交鲟血液生理指标变化,进而影响实验鱼生长性能。因此,在该养殖条件下推荐的养殖密度为9 kg/m3。     

海洋产业结构与海域承载力的匹配关系探讨——以辽宁省为例

海洋产业结构和海域承载力之间存在多种耦合匹配关系,其匹配程度是影响海洋经济健康持续发展的重要因素,而准确地定量化评价这种匹配关系是准确把握海洋产业结构是否失衡的关键环节。文章将海域承载力引入海洋产业结构问题研究中,首先对海洋产业结构水平和海域承载力定量化测算,在此基础上运用基于数列的匹配度计算方法测度辽宁省海域承载状况与海洋产业结构水平的匹配度,探讨海洋产业结构与海域承载力之间的匹配关系。结果表明:辽宁省海域承载力与海洋产业结构水平匹配度数值较高,二者之间存在较匹配的关系。     

Testing and modeling of the mechanical behavior of dolomite in the Wudongde hydropower plant

In order to understand the mechanical behaviours of the surrounding rocks in the underground caverns of the Wudongde hydropower plant, triaxial tests are performed on a type of dolomite. It is revealed that damage induced by crack development is the main factor controlling the nonlinear plastic deformation and failure behaviour of the dolomite in both pre- and post-peak regimes. Based on this understanding, a coupled elastoplastic damage model is developed for capturing the dolomite’s mechanical behaviours. In the model, the effects of plasticity and damage on rocks is described by introducing plastic hardening and damage softening commonly in the plastic yield surface. Which are both derived from a suitable Helmholtz free energy function. The model is used to simulate the triaxial tests. Comparisons between test results and the numerical modelling show that the developed model is capable of describing the macro mechanical behaviours of the Wudongde dolomite.     

Effects of size and strain rate on the mechanical behaviors of rock specimens under uniaxial compression

Size and strain rate are two key factors that dramatically influence the estimation of rock mechanical behaviors. To better understand the effects of size and strain rate on measured rocks, rock specimens with six different sizes were tested at six different strain rates under uniaxial compression using the MTS 815 Rock Mechanics Test System. Having determined that the size and strain rate significantly affect the peak strain, peak stress, elastic modulus, acoustic emission (AE), and failure pattern of the rock specimens, the relation was established between the strength and the size and strain rate of red sandstone. And the variation was revealed among the size and strain rate, the AE, and the failure pattern. It turned out that the peak stress was negatively correlated with the rock size and was positively correlated with the strain rate. When the length to diameter ratio (L/D) of the rock specimen was less than 2.0, the AE appeared mildly. The AE quantities gradually increased before the peak stress, and then sharply decreased after the peak stress. The failure pattern of the rock specimen was relatively complicated, with a fracture plane appearing along the axial direction. Conical failure type was also presented. When the L/D ratio of the specimen was greater than 2.0, the AE characteristics of red sandstone showed the radical model. There were relatively few AE rings before the peak stress. But the AE rings increased suddenly and dramatically during the peak stress. The rock specimens primarily failed with a single shear plane. Moreover, with an increase in the strain rate, the AE activities were enhanced and the AE quantities increased. When the strain rate of the rock specimen was less than 5.0?×?10^?4/s, the rock specimen failed with a shear or tensile-shear pattern. And when the strain rate was greater than 5.0?×?10^?4/s, the rock specimen tended to fail in a conical pattern.     

40Ar‐39Ar Dating of the Mahuaping W‐Be deposit,Northwestern Yunnnan Province,China, and its Geological Significance

正Objective Located near the intersection of Yangtze craton,TibetSanjiang orogen and Songpan-Ganzi orogen of Northwest Yunnan Province,the Mahuaping deposit is a unique large-scale tungsten-beryllium-fluorite ore deposit ever discovered in this area.In recent years,many studies have been carried out in Sanjiang Tethyan metallogenic belt and     

包气带反硝化强度空间分布规律的整合分析

依据1970~2017年间发表的3955篇包气带反硝化强度相关论文,筛选出197组反硝化强度数据,利用整合分析,重点研究了包气带反硝化强度在典型生态类型（水平）和不同采样深度（垂向）的空间分布规律,识别了包气带反硝化强度的主控因素并研究其函数关系。结果表明:水平空间上,包气带表层0~0.5 m反硝化强度的分布特征显著,由大到小排序为:森林（8.03±0.21 mg/（kg·d））、农田（3.54±0.08 mg/（kg·d））、草地（3.38±0.12 mg/（kg·d））、湿地（2.32±0.23 mg/（kg·d））、沙漠（2.15±0.56 mg/（kg·d））。垂向空间上（6 m内）,各生态类型反硝化强度随深度的增加均呈“S”型变化规律。不同生态类型和不同采样深度下包气带反硝化强度的主控因素存在一定差异,主要为黏粒、有机质、全氮、硝态氮、有效磷,并给出了包气带反硝化强度与主控因素的回归方程。     

美国声波钻进规程ASTM D6914/D6914M—16浅析

声波钻进技术具有速度快、岩心保真好、适用地层广等优点,广泛应用于工程勘察、环境调查、浅源地热、基础工程、矿山治理等领域。为了提高声波钻进施工质量和过程控制,美国材料与实验协会于2004年制定了第一部声波钻进规程D6914—04,后经多次修订完善,形成最新声波钻进规程D6914/D6914M—16。本文根据该版规程内容,从技术原理、钻进设备、成孔工艺等方面展开了阐述。当振动器与钻柱谐振频率重叠时,声波钻头受到的能量达到峰值。钻机和取心钻具是声波钻进的核心设备。成孔工艺主要以双管高频振动、低速回转为主,实现多种目的层的原位取心作业。标准相关内容对声波钻进技术在我国的持续推广具有参考意义。     

崩塌堆积体启动坡面泥石流判别与防治 ——以北川县开坪乡平石板泥石流为例

强震区地震后大量的崩塌堆积体堆积于高陡斜坡中上部,堆积体远离居民点,一旦诱发为坡面泥石流,形成新的次生地质灾害,将严重威胁下方居民的生命财产安全。本文以北川县开坪乡平石板坡面泥石流为例,平石板沟“5.12”地震崩塌堆积体在2010、2013年强降雨作用下失稳转变为坡面泥石流淤积场镇。在平石板泥石流暴发特征介绍基础上,通过粒径不均匀系数、堆积体启动判别指标、后缘汇水面积等来分析崩塌堆积体启动条件及影响因素,并针对此类灾害发育特征,提出了通过上游稳拦固源方法进行治理的防治思路。以期为研究高陡斜坡堆积体的启动机制及防治提供一定的借鉴意义。     

基于斜坡破坏模式的软弱变质岩区岩质滑坡易发性评价

滑坡受控于地质环境条件和坡体地质结构,不同地质结构的斜坡失稳破坏的模式存在差异,本文以后龙门山千枚岩区为例,基于现场调查,梳理总结了区内岩质滑坡发生的力学模式与斜坡地质环境、坡体结构之间的关系,进而选取控制滑坡发生的关键因素,运用ARCGIS软件的加权叠加功能定量划分了不同模式滑坡的易发区域,主要取得以下认识：（1）滑移—拉裂式滑坡主要发生在坡度30-45°的顺向飘倾坡内、滑移—溃曲式滑坡发生在坡度30-45°的顺向伏倾坡内、倾倒变形主要发生在岩层倾角大于65°的反向斜坡内;（2）区内倾倒变形易发区面积为8.73km2、滑移拉裂易发区面积为4.31m2、滑移溃曲易发区面积为3.28km2,以倾倒变形类型的滑坡为主,已发生滑坡与易发分区结果比对证明了滑坡易发分区与实际情况基本吻合。