土工试验规范变更对膨胀计算和判定的影响     

刘军  石鹏飞  孙凯 《岩土工程技术》2021,(2):134-136,F0003

对土工试验方法标准的新旧规范中无荷膨胀率和有荷膨胀率的变化内容进行对比分析,发现两者的计算公式发生显著变化,新规范的计算结果与旧规范相比,膨胀率明显变大,膨胀量随之增大,这将对工程勘察、设计、施工等产生明显影响。以某工程为例,新规范计算后地层总膨胀量由旧规范的16.7 mm变为51.8 mm,增加了2倍左右,地基土的胀缩等级由Ⅰ级变为Ⅱ级,地基基础设计等级由丙级变为乙级,地基处理措施和施工方案随之也发生改变。因此,工程技术人员对此应综合考虑,严谨对待。  相似文献   

温室气体排放的环境库兹涅茨曲线检验与减排路径的冲击动态——基于黑龙江省统计核算数据   总被引：1，自引：0，他引：1  

张滨  吕洁华 《气候变化研究进展》2019,15(1):84-94

基于2001-2015年黑龙江省温室气体排放统计核算数据,对地区GDP与温室气体排放的环境库兹涅茨曲线关系检验呈现倒U型,预期2019年达到理论拐点;通过偏最小二乘回归模型得到4个减排路径的年平均减排效果顺序依次为单位GDP化石能源消费量减少、经济结构调整、人均GDP增长、贸易结构变化;减排路径对应脉冲响应函数的动态冲击效果分别为波动性增排、收敛性减排、发散性减排、转变的排放作用;推动黑龙江省温室气体减排的路径顺序为控制化石能源消费量、优化经济结构、发展低碳经济、调整贸易结构。  相似文献   

Response of ocean dynamics to multiple equilibria of the Kuroshio path South of Japan     

《Dynamics of Atmospheres and Oceans》2019

Variability of the Kuroshio path to the south of Japan plays a central role in the local climate change and exerts tremendous influences on the local atmosphere and ocean. In this study, the response of ocean dynamics, in terms of the eddy kinetic energy (EKE), potential vorticity (PV), relative vorticity, and eddy-mean flow interaction, to the Kuroshio path change is discussed. Kuroshio path south of Japan includes the near-shore non-large meander (nNLM), the off-shore non-large meander (oNLM), and the typical large meander (tLM). Analyses reveal that the distribution of EKE, PV, relative vorticity, and energy exchange between the eddy field and the mean flow respectively varies with the Kuroshio path: (1) The tLM has the maximum EKE along the path; (2) The positive and negative PV are located at the onshore and offshore side of Kuroshio axis, respevetively; (3) The distributions of anomalous relative voritcity of nNLM, oNLM, and tLM are consistent with sea surface height anomalies (SSHAs); (4) The tLM has the largest energy exchange between the eddy field and the mean flow in terms of the rate of barotropic energy conversion. On the other hand, the stability analysis of ocean currents suggests that the three Kuroshio paths south of Japan have their own intrinsic properties of the instability.  相似文献   

混凝土框架柱双向受剪性能试验研究与相关性分析     

王铁成  王诚  梅廉 《地震工程与工程振动》2007,27(4):35-41

为研究钢筋混凝土框架柱的抗震性能,进行了矩形截面不等肢配箍混凝土框架柱在斜向水平荷载作用下的抗剪强度试验研究,对框架柱在斜向水平荷载作用下的受剪承载力进行有限元分析,并与试验结果进行比较,研究了两向不等肢配箍矩形截面柱在静载和低周反复荷载作用下双向受剪承载力的相关关系,推导了双向受剪承载力计算公式。研究结果表明,斜向水平荷载作用下,不等肢配箍混凝土框架柱双向受剪承载力的相关关系近似符合椭圆规律,为不等肢配箍混凝土框架柱的受剪承载力设计提供参考。  相似文献   

An assessment of Arctic cloud water paths in atmospheric reanalyses     

Mingyi Gu  Zhaomin Wang  Jianfen Wei  Xiaoyong Yu 《海洋学报(英文版)》2021,40(3):46-57

The role of Arctic clouds in the recent rapid Arctic warming has attracted much attention. However, Arctic cloud water paths(CWPs) from reanalysis datasets have not been well evaluated. This study evaluated the CWPs as well as LWPs(cloud liquid water paths) and IWPs(cloud ice water paths) from five reanalysis datasets(MERRA-2,MERRA, ERA-Interim, JRA-55, and ERA5) against the COSP(Cloud Feedback Model Intercomparison Project Observations Simulator Package) output for MODIS from the MERRA-2 CSP(COSP satellite simulator) collection(defined as M2 Modis in short). Averaged over 1980–2015 and over the Arctic region(north of 60°N), the mean CWPs of these five datasets range from 49.5 g/m~2(MERRA) to 82.7 g/m~2(ERA-Interim), much smaller than that from M2 Modis(140.0 g/m~2). However, the spatial distributions of CWPs, show similar patterns among these reanalyses, with relatively small values over Greenland and large values over the North Atlantic. Consistent with M2 Modis, these reanalyses show larger LWPs than IWPs, except for ERA-Interim. However, MERRA-2 and MERRA underestimate the ratio of IWPs to CWPs over the entire Arctic, while ERA-Interim and JRA-55 overestimate this ratio. ERA5 shows the best performance in terms of the ratio of IWPs to CWPs. All datasets exhibit larger CWPs and LWPs in summer than in winter. For M2 Modis, IWPs hold seasonal variation similar with LWPs over the land but opposite over the ocean. Following the Arctic warming, the trends in LWPs and IWPs during 1980～2015 show that LWPs increase and IWPs decrease across all datasets, although not statistically significant. Correlation analysis suggests that all datasets have similar interannual variability. The study further found that the inclusion of re-evaporation processes increases the humidity in the atmosphere over the land and that a more realistic liquid/ice phase can be obtained by independently treating the liquid and ice water contents.  相似文献   

川西九龙地区锂铍矿区土壤重金属分布特征及生态风险评价   总被引：1，自引：0，他引：1  

于沨  王伟  于扬  王登红  刘善宝  高娟琴  吕秉廷  刘丽君 《岩矿测试》2021,(3):408-424

川西九龙地区是近年来中国关键矿产资源勘查的热点地区之一,区内锂铍等稀有金属矿产资源优势突出,有望逐步发展成为国家级大型资源基地.作为长江上游生态保护屏障,该区生态环境脆弱,面对矿业开发的巨大机遇,在当前"环保优先"的现实情况下,急需摸清该区环境家底,支撑国家能源战略发展.本文用ICP-MS方法检测了该区352件土壤样品...  相似文献   

坠落物体产生的冲击荷载对海底管线的损伤分析     

张海  刘蕊  王秀存  田英辉 《海洋技术学报》2008,27(1):77-80

提出了坠落物体产生的冲击荷载对海底管线的损伤一种简易可行的分析方法。对坠落物体进行分类,然后进行运动形式分析,求得冲击速度,根据动力问题控制方程,使用著名商业软件‘ANSYS/LS-DYNA’,‘LS-DYNA’是世界上最著名的通用显式动力分析程序,对实际的工程算例进行了仿真模拟分析。得到的计算结果与已有经验方程结果是基本一致的。该方法可以和一般风险分析方法一起用作海底管线损伤分析和保护措施校核分析。  相似文献   

灌注桩基础工程质量事故的处理     

廖远淦 《南方国土资源》2000,13(4):67-70

灌注桩基础是珠江三角洲地区工业与民用建筑广泛采用的基础形式之一,但由于各种原因,发生质量问题的灌注桩基础屡见不鲜.本文简明地介绍了灌注桩基础工程质量事故概况、灌注桩质量检测和评价方法以及灌注桩质量事故处理的常用方法.  相似文献   

乐山市水资源承载力分析及开发潜力研究     

郭广元 《西部资源》2019,(2):77-79

水资源的供需关系已演变为限制经济社会不断发展的一个关键障碍,所以对水资源承载力展开探究,以支撑经济和社会的不断发展,将会具有现实意义和至关重要的影响,本文从水资源负载指数和承载指数模型出发,根据当前乐山市水资源情况现状,对当地水资源承载力进行分析。  相似文献   

Effects of long-term cyclic horizontal loading on bucket foundations in saturated loose sand     

《Applied Ocean Research》2019

A 1-g model experimental study was conducted to investigate the accumulated rotations and unloading stiffness of bucket foundations in saturated loose sand. One-way horizontal cyclic loading was applied to model bucket foundations with embedment ratios 0.5 and 1.0. Up to 10⁴ cycles of loading were applied at a frequency of 0.2 Hz varying load amplitudes. The accumulated rotation of the bucket foundations increased with the number of cycles and the load amplitudes. Empirical equations were proposed to describe the accumulated rotation of the foundations. The unloading stiffness of foundations increased with the number of cycles but decreased with an increase in load amplitude. The initial unloading stiffness of L/D = 1.0 (L is skirt length; D is foundation diameter) was approximately twice that of L/D = 0.5. Excess pore water pressure difference of 50% was observed between L/D = 0.5 and 1.0. The suction and static capacity of the bucket increased with increase of bucket embedment ratio with a difference of 69.5% and 73.6% respectively between L/D = 0.5 and 1.0.  相似文献