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   

特定场地下土工构筑物的几何可靠性分析     

吴兴征  王瑞凯  辛军霞 《岩土力学》2020,41(6):2070-2080

针对特定场地下土工构筑物的正常使用极限状态，采用近年发展的几何可靠性方法计算了多种构筑物的可靠度指标。考虑同一场地下的钻孔灌注桩、抗浮锚杆和CFG桩单桩加载变形测试曲线的离散性，各曲线回归参数呈现差异并可作为随机变量，进而探讨了各曲线回归参数间的相关性及联合分布特性。基于这些回归参数的联合发散概率密度等值线，即随机变量刚好达到极限承载能力状态，该几何可靠性算法可在随机变量的原始空间求得土工构筑物的可靠度指标。通过比对该几何可靠度指标与常规的一次可靠性算法成果，验证了该几何可靠性计算技术的可行性。计算表明，几何可靠性评价模型实施简便，易于被工程技术人员接受。  相似文献   

Undrained lower bound solutions for end bearing capacity of shallow circular piles in non-homogeneous and anisotropic clays     

Boonchai Ukritchon  Suraparb Keawsawasvong 《国际地质力学数值与分析法杂志》2020,44(5):596-632

The undrained bearing capacity of shallow circular piles in non-homogeneous and anisotropic clay is investigated by the lower bound (LB) finite element limit analysis (FELA) under two-dimensional (2D) axisymmetric condition using second-order cone programming, and the new solution of the problem is presented. Modified from the isotropic von Mises yield criterion, a cross-anisotropic undrained strength criterion of clays under the axisymmetric state of stress requiring three input shear strengths in triaxial compression, direct simple shear, and triaxial extension is employed in the 2D axisymmetric LB FELA. Parametric studies on the effects of pile embedment ratio, dimensionless strength gradient, anisotropic strength ratio, and pile roughness are investigated extensively, while the predicted failure mechanisms associated with these parameters are discussed and compared. Numerical results of undrained end bearing capacity of shallow circular piles are summarized in the form of design tables that are useful for design practice and represent a new contribution to the field of pile capacity considering the combined effects of undrained strength non-homogeneity and anisotropy.  相似文献   

改进的层次分析法与模糊综合评价在评估水库诱发地震震级上限中的应用          下载免费PDF全文

李龙师  金波  冯志仁 《世界地震工程》2020,(3):223-232

为了评估水库诱发地震震级上限，收集了150余例水库诱发地震的震例资料；利用改进的层次分析法优化了各评价指标的权重；应用模糊综合评价方法评估了水库诱发地震震级上限；结合二滩水电站水库诱发地震实例与目前评估水库诱发地震震级最常用的灰色聚类分析法的评价结果进行了对比分析。结果表明:层次分析法与模糊综合评价相结合的震级上限评估方法评价结果更加可靠，可对水库及水工建筑物的建设位置及抗震设防提供参考。  相似文献   

Land Resource Carrying Capacity in Xilin Gol Grassland Transects: A Perspective on Food Nutritional Demand     

YANG Wanni  ZHEN Lin  LUO Qi 《资源与生态学报(英文版)》2019,10(6):614-620

Food safety is an important issue for the development of the national economy and society. Studying regional food supply and demand from the perspective of land resource carrying capacity can provide new references for regional resource sustainability. This study uses the data from farmer and herdsmen household questionnaires, statistical data, land use data, and other sources to construct a land resource carrying capacity (LCC) assessment framework, targeting the food supply and demand of residents in representative areas, specifically the typical grassland pastoral areas, sandy pastoral areas and agro-pastoral areas on the Xilin Gol grassland transects. The three food nutritional indicators of calories, protein and fat were selected for analyzing the balance of land resource carrying capacity. We found that: 1) Along the Xilin Gol grassland, the main local food supply showed a shift from meat and milk to grains, vegetables and fruits. 2) From north to south along the grassland transects, the calorie intake increased gradually, while the intake of protein and fat was highest in pastoral areas and lowest in agricultural areas. 3) The overall land resource carrying capacity of the Xilin Gol grassland transects was in a surplus state, but the land carrying capacity of typical grassland pastoral area was higher than the two other types of areas. This study provides an empirical reference for the sustainable development of regional food nutrition.  相似文献   

海上风电升压站平台高程确定标准的合理性研究     

潘晓春 《海洋技术学报》2019,38(6):83-88

为保证海上风电升压电站建设的经济合理与安全可靠,合理确定海上风电升压电站平台高程十分必要。文中从波浪与潮位的遭遇组合、最大波高取值与现行相关标准的比较、最大波峰高度计算的合理性等方面,全面分析了确定海上风电升压站平台高程各组成项取值标准的合理性,研究认为现行标准明显偏高。建议海上升压站平台底部高程按"100年一遇极端高水位+重现期50年波列累积频率1%的最大波峰高度+安全超高"确定。结合工程实例计算分析,按本文建议可使海上升压站平台高程明显降低,从而节省工程造价,还可减轻升压站工程对周边风机的遮蔽影响,以达到多发电量的效果。  相似文献   

考虑冲刷影响的筒型基础竖向极限承载力研究     

陆罗观  刘润  练继建  陈广思 《海洋工程》2019,37(3):69-77

大直径宽浅式筒型基础,阻水宽度大,在位工作期间受波浪海流作用,其周围土体易被冲刷。为研究单侧地基土体受冲刷后筒型基础的竖向极限承载力变化,通过引进冲刷率的概念,采用有限元方法研究了不同冲刷率下筒型基础的竖向极限承载力;并基于Meyerhof理论建立了计算不同冲刷率下筒型基础竖向极限承载力的极限平衡方法。研究结果表明,随着冲刷率增大,筒型基础的极限承载力出现不同程度的下降,当冲刷率为0.8时,即筒型基础单侧土体冲刷深度达6.4 m时,筒型基础的竖向极限承载力折减率为3.28%。建立的极限平衡算法可准确计算冲刷条件下筒型基础的竖向极限承载力。  相似文献   

Experimental study on a sampling technique based on a freeze-sediments valve for deep-sea microorganism     

《Applied Ocean Research》2019

Deep-sea microorganism research has become a hot topic in life science, owing to its special value in high pressure and low temperature environment. If not kept the in-situ low temperature and high pressure, it will cause the microorganism to lose its activity and lead to a waste of resources. A freeze-sediments valve presents a promising solution to maintain the low temperature and high pressure in situ, improve the success rate of sampling and shorten the sampling time. A series of experiments were conducted to characterize the freeze-sediments valve, including the sampling time without leakage, adaptation to different sediments and the effect of the length, etc. Most important of all, temperature change of sediments is observed in all experiments. Experimental results indicated that the freeze-sediments valve was formed in 5 min without leakage and the freeze-sediments valve could be applied to different sediments without limitations on sediments type and mineral content. Considering the pressure retaining capacity and formation time of freeze-sediments valve, it was found that the freeze-sediments valve with a length of 60–80 mm has good pressure retaining capacity whose value was 41.3–48.4 Mpa and short formation time which was 5 min. Precooling the sampler could be used to shorten the sampling time in the actual environment application. This sampling technique can play a vital role in maintaining in-situ low temperature at −2 to −4 ° Celsius in all the experiments. According to the tests, the sampling technique based on the freeze-sediments valve had the potential to solve the problem of keeping in-situ temperature, low sampling success rate and long sampling time in the future.  相似文献   

Study of the flood control scheduling scheme for the Three Gorges Reservoir in a catastrophic flood          下载免费PDF全文

Shanghong Zhang  Zhu Jing  Wenda Li  Yujun Yi  Yong Zhao 《水文研究》2018,32(11):1625-1634

The Three Gorges Project is the world's largest water conservancy project. According to the design standards for the 1,000‐year flood, flood diversion areas in the Jingjiang reach of the Yangtze River must be utilized to ensure the safety of the Jingjiang area and the city of Wuhan. However, once these areas are used, the economic and life loss in these areas may be very great. Therefore, it is vital to reduce this loss by developing a scheme that reduces the use of the flood diversion areas through flood regulation by the Three Gorges Reservoir (TGR), under the premise of ensuring the safety of the Three Gorges Dam. For a 1,000‐year flood on the basis of a highly destructive flood in 1954, this paper evaluates scheduling schemes in which flood diversion areas are or are not used. The schemes are simulated based on 2.5‐m resolution reservoir topography and an optimized model of dynamic capacity flood regulation. The simulation results show the following. (a) In accord with the normal flood‐control regulation discharge, the maximum water level above the dam should be not more than 175 m, which ensures the safety of the dam and reservoir area. However, it is necessary to utilize the flood diversion areas within the Jingjiang area, and flood discharge can reach 2.81 billion m³. (b) In the case of relying on the TGR to impound floodwaters independently rather than using the flood diversion areas, the maximum water level above the dam reaches 177.35 m, which is less than the flood check level of 180.4 m to ensure the safety of the Three Gorges Dam. The average increase of the TGR water level in the Chongqing area is not more than 0.11 m, which indicates no significant effect on the upstream reservoir area. Comparing the various scheduling schemes, when the flood diversion areas are not used, it is believed that the TGR can execute safe flood control for a 1,000‐year flood, thereby greatly reducing flood damage.  相似文献   

阿拉善左旗5.8级地震前地脉动信号特征分析          下载免费PDF全文

梁沙沙  高立新  薛丁  戴勇  格根 《地震工程学报》2018,40(4):808-814

本文针对2015年4月15日发生在南北地震带北端的阿拉善左旗5.8级地震,利用乌海台、东升庙台、石嘴山台的连续数字地震波形资料,采用快速傅里叶变换对三个台站的2015年4月1日00时—4月15日23时波形数据进行分析,并持续跟踪0~0.25 Hz包络幅值极大值的变化形态。结果显示:(1)在5.8级地震前,震中附近的乌海地震台、东升庙地震台、石嘴山地震台记录的地震波形均出现频谱向低频偏移的现象;(2)三个台站出现低频异常的包络幅值极大值跟踪形态不一致,其中只有乌海台在震前出现明显的持续不稳定异常,异常持续时间约120h;(3)三个台站距离震中由近及远包络幅值极大值的跟踪形态差异明显。  相似文献