Numerical simulation of longitudinal settlement of shield tunnel in the coastal city Shanghai

Until now more than 14 subway lines are in operation and some new lines are being built in the coastal city Shanghai. The longitudinal settlement of shield tunnel has significant effect on the safety of the subway operation. In this paper, the deformation of the shield tunnel and the surrounding soil were analyzed by the establishment of a three-dimensional model. The vertical displacements of four paths (Path 1 is on the ground; Path 2 is at the top of the tunnel; Path 3 is in the middle of the tunnel; Path 4 is at the bottom of the tunnel) are affected by the nature of the soil. The horizontal displacement is smaller than the vertical displacement and horizontal displacement of the clay is larger than that of the sand. The distribution of the pore pressure changes with soil properties around the tunnel. The pore pressure of the sand layer is larger than that of the clay layer at the same depth of underlying soil.     

Global water vapor content decreases from 2003 to 2012: An analysis based on MODIS data

Water vapor in the earth′s upper atmosphere plays a crucial role in the radiative balance, hydrological process, and climate change. Based on the latest moderate-resolution imaging spectroradiometer(MODIS) data, this study probes the spatio-temporal variations of global water vapor content in the past decade. It is found that overall the global water vapor content declined from 2003 to 2012(slope b = –0.0149, R = 0.893, P = 0.0005). The decreasing trend over the ocean surface(b = –0.0170, R = 0.908, P = 0.0003) is more explicit than that over terrestrial surface(b = –0.0100, R = 0.782, P = 0.0070), more significant over the Northern Hemisphere(b = –0.0175, R = 0.923, P = 0.0001) than that over the Southern Hemisphere(b = –0.0123, R = 0.826, P = 0.0030). In addition, the analytical results indicate that water vapor content are decreasing obviously between latitude of 36°N and 36°S(b = 0.0224, R = 0.892, P = 0.0005), especially between latitude of 0°N and 36°N(b = 0.0263, R = 0.931, P = 0.0001), while the water vapor concentrations are increasing slightly in the Arctic regions(b = 0.0028, R = 0.612, P = 0.0590). The decreasing and spatial variation of water vapor content regulates the effects of carbon dioxide which is the main reason of the trend in global surface temperatures becoming nearly flat since the late 1990 s. The spatio-temporal variations of water vapor content also affect the growth and spatial distribution of global vegetation which also regulates the global surface temperature change, and the climate change is mainly caused by the earth's orbit position in the solar and galaxy system. A big data model based on gravitational-magmatic change with the solar or the galactic system is proposed to be built for analyzing how the earth's orbit position in the solar and galaxy system affects spatio-temporal variations of global water vapor content, vegetation and temperature at large spatio-temporal scale. This comprehensive examination of water vapor changes promises a holistic understanding of the global climate change and potential underlying mechanisms.     

Conceptualizing and measuring economic resilience of resource-based cities: Case study of Northeast China

This paper develops a conceptual model and an indicator system for measuring economic resilience of resource-based cities based on the theory of evolutionary resilience and the related concepts of persistence, adaptation, and transformation. Nineteen resource- based cities in Northeast China were analyzed using the indicator system. The results showed that Liaoning and Jilin provinces had higher economic resilience than Heilongjiang Province. Panjin, Benxi, and Anshan in Liaoning Province were the top three cities, while Shuangyashan and other coal-based cities in Heilongjiang Province ranked last. Metals- and petroleum-based cities had significantly higher resilience than coal-based cities. The differences in persistence, adaptability, transformation, and resilience among resource-based cities decreased since the introduction of the Northeast Revitalization Strategy in 2003. Forestry-based cities improved the most in terms of resilience, followed by metals-based and multiple-resource cities; however, resilience dropped for coal-based cities, and petroleum-based cities falling the most. The findings illustrate the importance and the way to develop a differentiated approach to improve resilience among resource-based cities.     

Local rainfall thresholds for forecasting landslide occurrence: Taipingshan landslide triggered by Typhoon Saola

This paper presents a case study of the Taipingshan landslide, which was triggered by Typhoon Saola in 2012. Taipingshan villa is one of the most famous scenic locations within the Taipingshan National Forest Recreation Area in northern Taiwan. Since the early 1990s, evidence of recent landslide activity appeared throughout the Taipingshan villa and included features such as tension cracks, ground settlement, and cracking in manmade structures. In response, a series of geological investigations and in-site/laboratory tests were conducted in 2010 to estimate slope stability and predict critical rainfall thresholds (event accumulated rainfall) for landslide activity. Results revealed that the critical rainfall threshold for the Taipingshan National Forest Recreation Area is 1765 mm. In 2012, that threshold was tested when Typhoon Saola brought tremendous rainfall to northern and eastern Taiwan and triggered activity along the main scarp of sliding mass B located near the History Exhibition Hall. According to in situ extensometer readings and on-site precipitation data, the extensometer was severed at an accumulated rainfall 1694 mm. Field monitoring data during the typhoon event are in good agreement with the rainfall threshold. These preliminary results suggest that the threshold may be useful for assessing the rainfall threshold of other landslides and a good reference for establishing early warning systems for landslides.     

云南都龙超大型锡锌多金属矿床中闪锌矿微量及稀土元素地球化学特征

云南马关都龙锡锌多金属矿床位于滇东南老君山锡锌钨多金属成矿区南部,是我国三大锡石硫化物矿床之一,目前对其矿床成因认识存在较大分歧。本文采用ICP-MS对都龙矿床中闪锌矿微量元素及稀土元素组成进行分析,以探讨该矿床成矿作用,为甄别已有成因观点提供证据。结果表明,矿床中闪锌矿以富集Fe、Mn、In、Co、Sn和贫Cd、Ga、Ge、Ni等元素为特征,成矿温度属于中—高温,其微量元素组成与白牛厂矿床(与燕山晚期花岗岩有关的矽卡岩型矿床)中的闪锌矿非常相似,和远源矽卡岩型铅锌矿床(核桃坪和芦子园)中闪锌矿存在一定差异,明显有别于喷流沉积型铅锌矿床(云南澜沧老厂和广东大宝山)中闪锌矿。此外,该矿床闪锌矿稀土配分模式多为轻稀土元素富集中等的向右倾斜曲线,以LREE/HREE值高、Eu负异常明显和Ce异常不明显为特征,与矿区燕山晚期隐伏花岗岩稀土元素特征基本一致,成矿物质来源以矿区燕山晚期隐伏花岗岩为主。结合近期矿山开采和地质勘探所揭露的矿化和矽卡岩蚀变的垂向分带等矿床地质特征,认为云南马关都龙锡锌多金属矿床属于与燕山晚期花岗岩有关的矽卡岩型多金属矿床,其中层状矽卡岩的形成应为成矿流体顺层交代的结果,矿化类型和围岩蚀变的分带与隐伏岩体的距离有关。     

Lithofacies paleogeography mapping and reservoir prediction in tight sandstone strata: A case study from central Sichuan Basin,China

Sand-rich tight sandstone reservoirs are potential areas for oil and gas exploration. However, the high ratio of sandstone thickness to that of the strata in the formation poses many challenges and uncertainties to traditional lithofacies paleogeography mapping. Therefore, the prediction of reservoir sweet spots has remained problematic in the field of petroleum exploration. This study provides new insight into resolving this problem, based on the analyses of depositional characteristics of a typical modern sand-rich formation in a shallow braided river delta of the central Sichuan Basin, China. The varieties of sand-rich strata in the braided river delta environment include primary braided channels, secondary distributary channels and the distribution of sediments is controlled by the successive superposed strata deposited in paleogeomorphic valleys. The primary distributary channels have stronger hydrodynamic forces with higher proportions of coarse sand deposits than the secondary distributary channels. Therefore, lithofacies paleogeography mapping is controlled by the geomorphology, valley locations, and the migration of channels. We reconstructed the paleogeomorphology and valley systems that existed prior to the deposition of the Xujiahe Formation. Following this, rock-electro identification model for coarse skeletal sand bodies was constructed based on coring data. The results suggest that skeletal sand bodies in primary distributary channels occur mainly in the valleys and low-lying areas, whereas secondary distributary channels and fine deposits generally occur in the highland areas. The thickness distribution of skeletal sand bodies and lithofacies paleogeography map indicate a positive correlation in primary distributary channels and reservoir thickness. A significant correlation exists between different sedimentary facies and petrophysical properties. In addition, the degree of reservoir development in different sedimentary facies indicates that the mapping method reliably predicts the distribution of sweet spots. The application and understanding of the mapping method provide a reference for exploring tight sandstone reservoirs on a regional basis.     

A comparative study of landslide susceptibility mapping using weight of evidence,logistic regression and support vector machine and evaluated by SBAS-InSAR monitoring: Zhouqu to Wudu segment in Bailong River Basin,China

The determining of landslide-prone areas in mountainous terrain is essential for land planning and hazard mitigation. In this paper, a comparative study using three statistical models including weight of evidence model (WoE), logistic regression model (LR) and support vector machine method (SVM) was undertaken in the Zhouqu to Wudu segment in the Bailong River Basin, Southern Gansu, China. Six conditionally independent environmental factors, elevation, slope, aspect, distance from fault, lithology and settlement density, were selected as the explanatory variables that may contribute to landslide occurrence based on principal component analysis (PCA) and Chi-square test. The relation between landslide distributions and these variables was analyzed using the three models and the results then used to calculate the landslide susceptibility (LS). The performance of the models was then evaluated using both the highly accurate deformation signals produced by using the Small Baseline Subset Interferometric Synthetic Aperture Radar technique and Receiver Operating Characteristic (ROC) curve. Results show more deformation points in areas with high and very high LS levels, and also more stable points in areas with low and very low LS levels for the SVM model. In addition, the SVM has larger area under the ROC curve. It indicates that the SVM has better prediction accuracy and classified ability. For the interpretability, the WoE derives the class of factors that most contributed to landsliding in the study area, and the LR reveals that factors including elevation, settlement density and distance from fault played major roles in landslide occurrence and distribution, whereas the SVM cannot provide relative weights for the variables. The outperformed SVM could be employed to determine potential landslide zones in the study area. Outcome of this research would provide preliminary basis for general land planning such as choosing new urban areas and infrastructure construction in the future, as well as for landslide hazard mitigation in Bailong River Basin.     

中国近海海表温度对气候变暖及暂缓的显著响应

基于多套全球海温再分析数据和2种线性趋势分析方法,评估了1958-2014年中国近海海表温度（SST）的变化及其对全球气候变化的响应特征,并与全球平均地表温度特别是与若干重要海区的SST做了比较。研究表明：在全球变暖的显著加速期（1980年代和1990年代）,中国近海区域年平均SST表现出更快速的升温特征,其速率达0.60℃/10a,是同期全球平均升温速率的5倍以上;在变暖暂缓期（1998-2014年）,中国近海SST出现显著的下降趋势。研究还表明,中国近海区域SST的年代际变化与太平洋年代际涛动（PDO）的位相转换一致,前者SST的快速上升（下降）期与PDO正（负）位相最大值的时期相对应,PDO可能是通过东亚季风和黑潮影响中国近海SST的年代际变化。     

疏勒河径流量与绿洲面积、农业产值及生态效益的关系

基于1954-2010 年疏勒河干流出山径流量、2000-2010年流域内灌区水资源供应量、灌区农作物种植类型、农作物及林草地面积等资料,通过建立系统动力学模型,探讨了气候变化背景下疏勒河径流量对绿洲的影响。结果表明:绿洲受径流量变化影响显著,若出山径流量按1954-2010 年变化趋势增加,绿洲面积、农业产值、生态效益将有不同程度增加; 若出山径流量减小,绿洲面积、农业产值、生态效益亦相应减小。2020年出山径流量较2010年分别减少5%、10%、15%时,绿洲面积和农业产值相应减小4.5%、8.9%、13.4%。在径流量不变情况下,若普及常规节水,林、草地面积均增加16%以上; 若普及高效节水,林、草地面积均扩大54.7%; 若提高渠系利用率到0.70,林草地面积扩大5%以上,总产值增加5.4%; 若提高渠系利用率到0.75,林草地面积增加12%以上,总产值增加12.2%。     

新疆尼勒克、巩留交界6.0级地震灾害损失评估与房屋震害特征

新疆尼勒克、巩留交界6.0级地震震中烈度为Ⅶ度,地震没有造成人员伤亡,但个别民宅倒塌,大量村镇居民房屋遭受中等以上破坏,一些教育、卫生等公房遭破坏;交通和水利设施有一定程度破坏,经及时抢修,未对灾区生产生活产生明显影响。通过实地抽样调查和统计计算,评估出本次地震造成的直接经济损失为67 846万元,需恢复重建的经费120 349万元。