粤港澳大湾区人口老龄化时空特征及其经济效应     

李琼  李松林  张蓝澜  李昊  刘毅 《地理研究》2020,39(9):2130-2147

中国新时代“两个十五年”的现代化强国战略周期,恰恰是快速人口老龄化纵深发展期,人口年龄结构快速老龄化与经济社会之间的发展不平衡矛盾将日益严峻。本文利用广东省第四次、第五次、第六次人口普查资料、2015年广东省1%人口抽样调查资料、香港统计年刊和澳门统计年鉴数据,运用空间自相关分析法、柯布-道格拉斯生产函数和空间回归等方法,研究2000—2015年粤港澳大湾区人口老龄化的时空特征及其经济效应,结果表明：① 粤港澳大湾区人口老龄化进程慢于广东省,更慢于全国,但于2015年已进入老年型I期。② 粤港澳大湾区老龄化呈动态演变特征,空间上以香港和江门为起点,经西北向北扩散的“C”型分布模式,高收入城市以澳门和香港为起点向北扩散,最终形成中心-外围的空间分布格局。③ 粤港澳大湾区人口老龄化对经济增长具有负向影响,老龄人口增加1%,人均GDP降低3%。人均固定资本投入和人均人力资本投入有正的经济效应,人均人力资本投入带来的正向效应要大于人均固定资本投入。鉴于此,粤、港、澳三地应建立起协同治理模式,构建跨境的养老合作机制;促进产业结构升级,充分利用人力资本促进技术创新,并正确评估不同阶段人口老龄化对经济增长的影响,妥善处理好人口老龄化与经济之间的关系至关重要。  相似文献   

资源环境承载协调理论与评价方法     

李瑞敏  殷志强  李小磊  刘琼  孟晖  黄道袤  王轶  王龙平  王欣宝  刘建奎  孙超  赵德刚 《地质通报》2020,(1):80-87

资源环境承载能力评价是进行国土空间规划和用途管控的基础性工作,越来越受到国家重视。在资源环境承载能力研究实践中,以自然资源环境系统及其与社会经济系统的关系为主要研究对象,创新性提出了"资源环境承载协调理论",并基于此理论初步建立了不同空间尺度的地质资源环境承载能力评价技术方法,构建了地质环境、地下水资源、矿产资源等不同资源环境要素的承载能力评价指标体系,包括承载本底评价指标和承载状态评价指标。规范了不同尺度的资源与环境承载能力评价流程,为有序推动全国、区域及市县尺度的自然单元和行政单元的地质资源环境承载能力评价工作提供了强有力的。  相似文献   

场地类别分类方案研究     

陈国兴  丁杰发  方怡  彭艳菊  李小军 《岩土力学》2020,41(11):3509-3522

基于性能的抗震设计，要求工程师设计出具有预期抗震性能的结构，一个关键因素是地震作用的确定，这在很大程度上取决于局部场地条件。通过收集和分析北京、苏州和唐山城区956个钻孔资料，建立地表20 m和30 m深土层走时平均剪切波速VS20和VS30的关系式；现场钻探获取北京城区深105 m的典型钻孔原状土样，试验给出各类土体动剪切模量和阻尼比曲线；建立北京城区170个钻孔的场地反应计算模型，采用Nakamura提出的HVSR法和陈国兴等提出的弱震法估算场地基本周期TS值，结合国内外现行抗震规范的场地分类及一些学者对场地分类的研究成果，提出两种新的场地分类建议方案：基于等效剪切波速VSE和覆盖土层厚度H（地表至剪切波速VS ≥ 500 m/s的基岩深度）的双指标场地分类方案及基于VSE、H和TS的三指标场地分类方案。提出的场地分类方案对我国现行抗震规范场地分类方法的改进有参考价值。  相似文献   

四川盆地川南地区五峰组—龙马溪组页岩储层分类评价     

郭建林  贾成业  何东博  李林  朱汉卿  周倚  刘畅 《高校地质学报》2020,26(3):323-332

文章在资源评价和有利区优选的基础上，建立了川南地区五峰组—龙马溪组页岩储层分类评价标准。确定孔隙度（Φ） 大于3%，含气饱和度（Sg） 高于30%，岩石骨架密度（DEN） 低于2.7 g/cm³，脆性指数（BI） 高于40%时，对应含气量（Vt） 高于1 m³/t，可识别出储层与非储层，是有效储层识别的标准。采用地质工程一体化评价思路，选取含气量表征页岩储层物质基础，与孔隙度和有机质丰度正相关；选取脆性指数评价工程可压性，与硅质和碳酸盐岩含量正相关，明确了含气量和脆性指数可综合表征页岩储层地质和工程两方面特征。进一步将有效储层划分为三类：I类储层含气量（Vt） 高于4 m³/t，脆性指数（BI）高于50%；II类储层含气量与脆性指数中任何一项低于4 m³/t或50%；三类储层含气量（Vt）介于1~4m3/t，脆性指数（BI） 为40%~50%。川南地区五峰组—龙一1亚段各小层品质较好，以I、II类储层为主，局部为III类储层。采用该分类评价标准，评价水平井实际钻遇储层品质，Ⅰ类储层比例与气井测试产量、EUR间呈正相关，且当Ⅰ类储层钻遇率高于50%，气井测试产量超过15×104 m³/d概率达到92%，对应气井EUR在8000×104 m³以上，达到效益开发的要求。  相似文献   

劲芯水泥土桩承载路堤渐进式失稳破坏机制     

张振  张朝  叶观宝  王萌  肖彦  程义 《岩土力学》2020,41(6):2122-2131

劲芯水泥土桩是一种软土地基处理的新方法，近年来已成功应用于公路、铁路路基处理工程中。然而由于人们对其承载路堤的失稳破坏机制认识不足，无法正确指导设计。采用反映桩体材料破坏后特征的应变软化模型，模拟劲芯水泥土桩承载路堤失稳破坏1g模型试验，通过分析路堤失稳破坏过程中桩体塑性区的开展和桩身受力的变化情况，研究了桩体的破坏顺序及其破坏模式。结果表明：路堤失稳过程中，劲芯水泥土桩并非同时发生破坏，路面正下方桩体首先发生受压破坏，坡面下方桩体自坡脚至坡肩依次发生弯剪破坏；由于桩体的存在，路基中滑动面并非完全穿过桩体破坏位置。基于桩体破坏顺序、破坏模式、受力情况变化，以及荷载传递规律，阐释了劲芯水泥土桩承载路堤渐进式失稳破坏机制。采用现行规范中基于残余强度的柔性桩处理方法，计算的安全系数与试验结果较为接近，但其适用性还需做进一步研究。  相似文献   

Constitutive modelling of fine-grained gassy soil: A composite approach     

Zhiwei Gao  Yi Hong  Lizhong Wang 《国际地质力学数值与分析法杂志》2020,44(9):1350-1368

Fine-grained marine sediments containing large undissolved gas bubbles are widely distributed around the world. Presence of the bubbles could degrade the undrained shear strength (s_u ) of the soil, when the gas pressure u_g is relatively high as compared with the effective stress in the saturated soil matrix. Meanwhile, the addition of bubbles may also increase s_u when the difference between u_g and pore water pressure u_w becomes smaller than the water entry value, causing partial water drainage from the saturated matrix into the bubbles (bubble flooding) during globally undrained shearing. A new constitutive model for describing the two competing effects on the stress-strain relationship of fine-grained gassy soil is proposed within the framework of critical state soil mechanics. The gassy soil is considered as a three-phase composite material with compressible cavities, which allows water entry from the saturated matrix. Bubble flooding is modelled by introducing an additional positive volumetric strain increment of the saturated clay matrix, which is dependent on the difference between pore gas and pore water pressure based on experimental observations. A modified hardening law based on that of the modified Cam clay model is employed, which in conjunction with the expression for bubble flooding, can describe both the detrimental and beneficial effects of gas bubbles on soil strength and plastic hardening in shear. Only two extra parameters in addition to those in the modified Cam clay model are used. It is shown that the key features of the stress-strain relationship of three fine-grained gassy soils can be reproduced satisfactorily.  相似文献   

联合升降轨Sentinel-1A的地表形变监测技术研究          下载免费PDF全文

陈有东  何毅  张立峰  王文辉  唐源蔚 《海洋测绘》2020,40(4):59-64

河谷型、海岸带、海岛礁以及滩涂等区域地表形变信息的准确获取,迫切且关键。利用25景升轨和28景降轨Sentinel-1A数据,基于SBAS-InSAR技术,获取兰州城区2014年10月~2016年9月的地表沉降速率图和沿视线方向(line-of-sight,LOS)的时相位移量,探讨升降轨数据在河谷型城市地表形变监测中的适用性。结果表明:升降轨Sentinel-1A数据之间的时相位移量具有高度关联性,其中升轨数据在地形起伏较大区体现出良好的干涉性,而降轨数据在平坦区表现出较好的监测能力。兰州城区大部分区域处于稳定状态,但沙井驿、九州、小达坪、东岗、伏龙坪、西客站以及周边区域地表存在沉降趋势,最大沉降速率可达30 mm/年。联合升降轨Sentinel-1A数据监测河谷型、海岸带、海岛礁以及滩涂等区域地面沉降具有可行性和可靠性。  相似文献   

海洋测绘标准体系建设需求分析与总体方案          下载免费PDF全文

翟国君  吴太旗  陆秀平  陆毅  滕惠忠  孙万民 《海洋测绘》2020,40(1):1-5

分析了海洋测绘标准体系建设现状和新形势对海洋测绘标准体系建设的需求,在分析研究相关领域标准体系的基础上,依据《标准体系表编制原则和要求》,拟制了海洋测绘标准体系框架,并初步拟制了5大类21小类共247项各级别的标准名称、宜定级别等,可为海洋测绘领域的工作提供基础性技术支持,为海洋测绘标准的制修订工作奠定基础。  相似文献   

How soil texture,channel shape and cross-sectional area affect moisture dynamics and water loss in irrigation channels     

Zhifan Mu  Tianxiao Li  Dong Liu  Qiang Fu  Renjie Hou  Qinglin Li  Yi Ji  Song Cui  Mo Li 《水文研究》2021,35(4):e14155

To enhance the utilization efficiency of farmland irrigation water and reduce the leakage of water conveyance channels, the leakage process of channels was simulated dynamically. The simulated results were compared with data measured in laboratory experiments, and the performance of the model was evaluated. The results indicated that the simulated values of the model were consistent with the observation values, and the R² values varied between 0.91 and 0.99. In addition, based on the laboratory experiments, a water supply system (Mariotte bottles) and soil box were built using plexiglass. Three influencing factors, namely, the channel form, soil texture and channel cross-sectional area, were varied to observe and calculate the resulting cumulative infiltration amount, infiltration rate and wetting front migration distance. HYDRUS-3D software was used to solve the three-dimensional soil water movement equation under different initial conditions. The results demonstrated that the U-shaped channel was more effective than the trapezoidal channel in increasing the utilization efficiency of the water resources. A U-shaped channel with a small channel cross-sectional area should be adopted and the soil particle size should be prioritized in the construction of water conveyance channels for farmlands. The simulation results were in agreement with the observed results, which indicates that HYDRUS-3D is a reliable tool that can accurately simulate the soil moisture movement in water conveyance channels. The research results can provide a reference for the design and operation of farmland irrigation systems.  相似文献   

Assessing Cryptic Invasion State: Fine-Scale Genetic Analysis of Ciona savignyi Population in Putative Native Habitat of the Korean Coast     

Yi  Chang Ho  Kim  Won 《Ocean Science Journal》2020,55(1):99-113

The solitary ascidian, Ciona savignyi (Ascidiacea, Enterogona) is a notorious marine invader still expanding its habitat range worldwide. This species is considered native to the North West Pacific, but its indigeneity in Korean coastal waters has been questioned because of outdated taxonomic records and its inhabitation of oceanographically marginal areas. To clarify their cryptic invasion state, 247 individual C. savignyi samples were collected from 12 harbors and marinas on the Korean coast, and a 744 bp region of mitochondrial DNA (mtDNA) cytochrome c oxidase subunit I gene was sequenced and analyzed. Our analyses of population genetic structure and demographic history provided considerable pieces of evidence supporting their long-term establishment on the Korean coasts: differentiated population genetic structure, sequentially arrayed star-shape haplotype network, neutrality test results of past population expansions, and post-glacial colonization pattern of demography. Consequently, we concluded that C. savignyi populations on the Korean Coast are indigenous rather than exotic. These results could be used as reference data for further phylogeo graphic and demographic studies of problematic Ciona species, and to clarify and resolve similar cryptic invasion states of the other Korean coastal marine organisms. This study is the first to resolve the cryptic in vasion state of Korean marine organisms using genetic analysis.

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