井点降水施工经验浅谈

中国人民银行阿克苏地区中心支行发行库、营业办公用房工程施工时由于地下水位较高(地下稳定水位为-3.8m,设计基底标高为-5.8m),且地下水丰富,采取管井井点降水方案,保证施工不受地下水的影响,防止基坑外的地下水位下降对周围已有建筑物、管线、道路路面所造成的各种危害.     

地下水浮力对地下建筑结构安全的影响

在本文中,笔者首先研究地下水水位下降对建筑结构的影响,然后分析地下水位下降对建筑地基的影响,最后提出应对措施.     

地下水浮力对地下建筑结构安全的影响

在本文中，笔者首先研究地下水水位下降对建筑结构的影响，然后分析地下水位下降对建筑地基的影响，最后提出应对措施。     

吉林省城市地质灾害类型及防治对策

一、分布类型及成因吉林省城市地质灾害主要包括地下水位下降、地面沉降、泥石流、地下水质污染等,其成因主要受内外动力、地质条件和人类活动程度等因素控制。1、地下水位下降地下水位下降主要指由于大量开采地下水而引起的区域性水位下降并形成大面积的降落漏斗。主要分布在我省的长春、四平和其他以地下水作为水源的中小城市。在这些地区,由于城市发展对地下水的需求量增加,无计划的过量或超量开采,使地下水天然的补给径流和排泄关系失衡,抽出的地下水得不到及时的补充,从而形成区域地下水位下降,持续开采便产生降落漏斗。2、地面沉降这类灾害在我国长江三角洲和华北平原的一些大中城市比较常见。地面沉降同地下水位下降一样,     

繁华城区下穿浅基建筑群地面建筑保护措施施工技术研究

某建筑房屋位于暗挖隧道正上方，该房屋为5层混凝土整体框架结构，柱下独立基础，拱顶埋深15～17m，隧道拱顶为砾（砂）质粘土和全砾粘土，围岩类型为Ⅵ级，在地下水作用下易软化，根据施工阶段打设水位观察孔测量地下水埋深16m。     

地下水灌溉农田的水量供需平衡计算

一、供水量计算 地下水补给量计算。地下水可供水量双开采区能有多少补给地下含水层，用补给量表示，开采量超过补给量造成地下水水位下降，因此开采量不能超过补给量。     

国务院颁布《全国地下水污染防治规划》

国务院总理温家宝日前主持召开国务院常务会议,讨论通过《全国地下水污染防治规划（2011-2020年）》。会议指出,随着我国城市化、工业化进程加快,部分地区地下水超采严重,水位持续下降;一些地区城市污水、生活垃圾和工业废弃物污液以及化肥农药等渗漏渗透,造成地下水环境质量恶化、污染问题日益突出,给人民群众生产生活造成严重影响。     

海岸工程场地岩土工程勘察的水文地质条件分析——以北海市外沙岛某工程为例

临海建筑工程场地地下水与海水水力联系密切,基坑降水分析计算、抗浮设计水位、地下水对混凝土结构的侵蚀性分析等均需合理考虑潮汐效应和海水的影响。     

对地下室防水结构设计的探讨

地下室属于隐蔽工程,如果在今后使用过程中出现漏水现象,后果将不堪设想,由于地下室设置在地面以下,在地下水位较高的区域,地下室绝大部分处于地下水中;即使在地下水位较低区域,由于雨季的影响,雨水和地表水通过土层渗入而存于弱透水性土层中形成上层滞水,也会引起地下水渗漏.     

高层建筑地下室防水施工技术特点浅析

随着城市建设的迅猛发展，高层建筑大量涌现。高层建筑为满足抗震、抗风、人防和使用功能的要求，一般都设有一层或多层地下室。由于地下室设置在地面以下，在地下水位较高区域，地下室绝大部分处于地下水巾；即使在地下水位较低区域，由于雨季的影响，雨水和地表水通过土层渗入而存于弱透水性土层中形成上层滞水，也会引起地下水渗漏。因此地下室必须具备良好的防水性能，这直接影响到建筑物的使用功能和寿命。     

Groundwater balance and conservation under different water pricing and agricultural policy scenarios: A case study of the Hamadan-Bahar plain

Government subsidies for agricultural activities in recent decades have encouraged farmers of Hamadan-Bahar plain to extend the number of wells and irrigated farms, with no consideration of groundwater resource conservation. As a result, the level of the groundwater table has decreased continuously in this area, threatening the life of groundwater aquifer. The objective of the study is to analyze the impacts of irrigation water pricing and agricultural policy scenarios on aquifer conservation by considering the dynamic relations between aquifer groundwater balance and the agriculture sector. For this purpose a combination of simulation and optimization techniques is considered in a dynamic framework. Firstly, dynamic treatments of groundwater and the main factors affecting the balance of studied aquifer are simulated. Then, optimization behaviour of agriculture sector related to farmers' decision-making processes is defined on the time horizon. Thereafter all of the equations are used simultaneously by a non-linear dynamic programming method, which maximize present value of gross margins of agriculture sector subject to groundwater constrains and other input limitations. The analysis of the results indicates that water pricing by itself can considerably reduce the agricultural demand for aquifer groundwater in the Hamadan-Bahar plain.     

On the spatial nature of the groundwater pumping externality

Most existing economic analyses of optimal groundwater management use single-cell aquifer models, which assume that an aquifer responds uniformly and instantly to groundwater pumping. In this paper, we develop an economic model of groundwater management that explicitly incorporates spatial dynamic groundwater flow equations. Calibration of our model to published economic studies of specific aquifers demonstrates that existing studies generally incorrectly estimate the magnitude of the groundwater pumping externality relative to spatially explicit models. In particular, for large aquifers with surface areas of thousands of square miles, the marginal pumping externality predicted by single-cell models may be orders of magnitude less than that predicted by a spatially explicit model, even at large distances from a pumping well. Conversely, for small aquifers with areas of a few hundred square miles or less, single-cell models reasonably approximate the pumping externality. Application of single-cell models to inappropriate settings may result in misleading policy implications due to understatement of the magnitude and spatial nature of the groundwater externality.     

Property rights and groundwater management in the High Plains Aquifer

Groundwater is an important natural resource that needs to be managed dynamically. Ideally, institutions governing property rights to the groundwater of low-recharge aquifers should not discourage or disincentivize groundwater users from dynamic management. We develop an empirical model to examine whether agricultural groundwater users faced with prior appropriation property rights to groundwater in western Kansas exhibit dynamic, forward-looking behavior consistent with dynamic management. We find that although farmers are allotted a time-invariant maximum amount of groundwater that they can extract each year, they still behave in a manner consistent with dynamic management. Their groundwater extraction decisions are not significantly affected by the quantity they are authorized to extract, but are instead affected by expected future crop prices, expected future energy prices, and groundwater extraction by neighbors. Our results provide evidence that farmers manage their groundwater resource dynamically, even if their property rights do not necessarily encourage or incentivize them to do so.     

Monopoly Power and Distribution in Fragmented Markets: The Case of Groundwater

This paper examines monopoly power in the market for groundwater (irrigation water extracted by private tubewells), a market characterized by barriers to entry and spatial fragmentation. In Pakistan's Punjab region, groundwater and tenancy contracts are often interlinked, with share-tenants gaining access to water through the use of their landlord's tubewell. An analysis of groundwater transactions shows that tenants of tubewell owners are charged lower prices than other customers. Tubewell owners and their tenants also use considerably more groundwater on their plots than other farmers. Using detailed price and quantity data, the efficiency and distributional implications of this monopoly power are explored.     

山东省电子商务发展水平的地域特征及影响因素

以阿里研究院提供的2015年县域电子商务发展指数为测度指标,综合运用探索性空间数据分析、空间变差函数、因子分析和地理加权回归等方法,研究山东省86个县域电子商务发展水平的空间分异特征与影响因素。结果表明:(1)县域电子商务发展水平整体较低,空间分异格局鲜明,呈现出由山东半岛向中西部地区递减的特征。(2)发展水平的空间相关性较强,形成了稳定的空间集聚结构,高值集聚区主要分布在青岛、烟台、潍坊等地区,低值集聚区主要分布在临沂、菏泽、德州等地区。(3)电子商务发展指数和电商应用指数的空间变异主要受相关性的影响,网购指数的空间变异受随机成分的影响较大。(4)城镇化、经济发展与信息化水平等因素对县域电子商务发展水平有正向促进作用且影响程度存在明显的空间差异;从回归系数的平均值看,影响程度从大到小依次为城镇化水平、经济与信息化发展水平、金融发展水平、交通与产业发展水平。     

产业互动外部性、生产性服务业集聚与城市创新力--对我国七大城市群的一项实证比较

城市群经济在我国经济版图中扮演越来越重要的角色,正成为创新扩散的主要载体和经济增长的新引擎。生产性服务业作为高技术含量的知识密集型产业,其分布与结构的合理性对城市及城市群形成创新竞争力有重要意义。从产业互动外部性与产业集聚外部性角度切入,将城市群作为产业集聚的空间载体,利用2003-2016年我国七大城市群127个城市的面板数据构建动态空间面板模型,考察生产性服务业相对专业化集聚及相对多样化集聚对城市创新力的影响,进而探讨这种影响在城市群之间的差异性。实证结果显示:(1)生产性服务业相对集聚具有空间溢出效应,即某一城市创新力受当地和相邻地区生产性服务业相对集聚水平的影响。(2)就全国整体而言,对城市创新力有持续性影响的主要是相对多样化集聚而非相对专业化集聚,通过生产性服务业嵌入制造业价值链形成动态比较优势来实现城市创新能力的提升。(3)考虑区域异质性的回归结果表明,生产性服务业相对集聚程度对不同发展阶段不同发展模式的城市群内城市创新产生显著的差异性影响。     

区域公共卫生服务收敛性研究——基于动态空间面板模型的实证分析

本文在现有财政支出收敛理论和经济增长空间收敛模型基础上,构建了公共卫生服务动态空间收敛理论模型,并采用动态空间面板收敛模型对1997-2006年中国大陆30个省、市、自治区公共卫生服务收敛情况进行了实证检验,结果发现:地区间公共卫生服务并不存在绝对收敛,但是存在条件收敛,差距有所缩小。财政收入的提高、居民收入水平的提高和中央政府转移支付的增加分别从供给、需求和收入效应的角度提高了地区公共卫生服务供给水平。但是,地区间公共卫生服务供给存在显著的空间负效应,降低了地区间公共卫生服务收敛速度,省级政府间未形成趋好竞争,反倒形成了逐底竞争。     

A dynamic approach to PES pricing and finance for interlinked ecosystem services: Watershed conservation and groundwater management

A theory of payment for ecosystem services (PES) pricing consistent with dynamic efficiency and sustainable income requires optimized shadow prices. Since ecosystem services are generally interdependent, this requires joint optimization across multiple resource stocks. We develop such a theory in the context of watershed conservation and groundwater extraction. The optimal program can be implemented with a decentralized system of ecosystem payments to private watershed landowners, financed by efficiency prices of groundwater set by a public utility. The theory is extended to cases where land is publicly owned, conservation instruments exhibit non-convexities on private land, or the size of a conservation project is exogenous. In these cases, conservation investment can be financed from benefit taxation of groundwater consumers. While volumetric conservation surcharges induce inefficient water use, a dynamic lump-sum tax finances investment without distorting incentives. Since the optimal level of conservation is generated as long as payments are correct at the margin, any surplus can be returned to consumers through appropriate block pricing. The present value gain in consumer surplus generated by the conservation-induced reduction in groundwater scarcity serves as a lower bound to the benefits of conservation without explicit measurement of other benefits such as recreation, biodiversity, and cultural values.     

Convergence,technological interdependence and spatial externalities: a spatial dynamic panel data analysis

This study adopts a spatial dynamic panel data approach and spatial quasi-maximum likelihood to re-estimate the speed of growth convergence in 91 countries based on technological interdependence and spatial externalities. We perform a conditional Lagrange multiplier test for spatial error dependence and find some differences to previous studies. First, the switch from a cross-sectional to a dynamic panel data framework enables the estimated rate of conditional convergence to be higher, more accurate and more appropriate for realistic and theoretical expectations. Second, the spatial Durbin model (SDM) is a general form of simplified model that considers spatial error correlation, and its likelihood ratio test for the theoretical model of ‘learning by doing’ effect provides further evidence. Finally, statistical tests find that spatial correlation not only occurs in each variable, but also appears in the error term. Thus, the SDM does not exist in the assumptions associated with the spatial error, which are not necessarily correct.     

Democracy and Economic Growth in an Interdependent World

We model dynamic interdependence in cross‐country economic growth processes by allowing it to vary according to democratic distance among economies. Stochastic distributional dynamics and temporal effects of democracy on economic growth are studied, and spatial variation in economic growth is explored. Among important results, democratic poverty trap is found to exist indicating the possibility of persistence of (un)stable democratic equilibria at different levels of democracy. Our cross‐sectional regression evinces that democracy has exerted significant growth‐enhancing effect and that the democratic distribution has steadily shifted locus from low‐level to high‐level equilibrium. Our spatial analysis of democracy‐economic growth nexus provide evidence of significant dynamic spatial autocorrelation and complementarity among countries' growth processes. Finally, it is demonstrated that the relevance of geographical proximity in facilitating interdependence in economic growth is overshadowed by relational proximity.