Effects of Wave–Current Interaction on Salt Intrusion During a Typhoon Event in a Highly Stratified Estuary

Wave–current interaction (WCI) is important in modulating hydrodynamics and water mixing in estuaries, and thereby the transport of water-borne materials. However, the effects of WCI on salt transport and salt intrusion in estuaries during storm events have been rarely examined. In the present study, we use a coupled atmosphere–ocean–wave–sediment transport (COAWST) modeling system to investigate the effects of WCI on salt intrusion in the highly stratified Modaomen Estuary during Typhoon Hagupit (2008). The model is validated by the measured wave, water elevation, and surface salinity data, and several diagnostic model experiments are conducted. WCI increases the storm surge by 0.8 m at the peak surge (25% of the total surge height). The wave-breaking-induced momentum flux and the Stokes drift increase the magnitude of the landward flow by 0.3 m s^?1 (30% of the total landward flow). In addition, the waves increase water mixing by 2–4 times compared with that without waves. Hence, WCI significantly increases the landward advective salt transport and decreases the steady shear transport. The net effect of the WCI is a significant increase of salt import and salt intrusion during the typhoon event. However, in the aftermath of the storm, the imported salt water is rapidly flushed out by the increased river discharge, and the estuary regains its stratification within one day.     

Real-time identification of urban rainstorm waterlogging disasters based on Weibo big data

With the acceleration of urbanisation in China, preventing and reducing the economic losses and casualties caused by urban rainstorm waterlogging disasters have become a critical and difficult issue that the government is concerned about. As urban storms are sudden, clustered, continuous, and cause huge economic losses, it is difficult to conduct emergency management. Developing a more scientific method for real-time disaster identification will help prevent losses over time. Examining social media big data is a feasible method for obtaining on-site disaster data and carrying out disaster risk assessments. This paper presents a real-time identification method for urban-storm disasters using Weibo data. Taking the June 2016 heavy rainstorm in Nanjing as an example, the obtained Weibo data are divided into eight parts for the training data set and two parts for the testing data set. It then performs text pre-processing using the Jieba segmentation module for word segmentation. Then, the term frequency–inverse document frequency method is used to calculate the feature items weights and extract the features. Hashing algorithms are introduced for processing high-dimensional sparse vector matrices. Finally, the naive Bayes, support vector machine, and random forest text classification algorithms are used to train the model, and a test set sample is introduced for testing the model to select the optimal classification algorithm. The experiments showed that the naive Bayes algorithm had the highest macro-average accuracy.     

北秦岭西段早侏罗世A型花岗岩及其地质意义

本文通过岩相学、岩石地球化学、锆石U?Pb定年和Lu?Hf同位素组成分析等方法,对出露于北秦岭西段宝鸡岩体王家山一带的黑云母花岗岩和其中的包体进行了研究。结果表明,该花岗岩形成时代为187±2 Ma,属于高钾钙碱性—钾玄岩系列岩石,富集Rb、Th、U等大离子亲石元素以及Nb、Zr和Hf等高场强元素,亏损Ba、Sr和Eu,具有高的全岩锆石饱和温度(825℃~838℃),显示A型花岗岩特征,形成于造山后的板内环境,可能为秦岭岩群副变质岩与安山质岩石部分熔融的产物。暗色包体显示塑性流变特征,具有岩浆结构,发育针状磷灰石和具有复杂成分环带的更长环斑结构长石,是幔源岩浆注入酸性岩浆发生混合作用的产物,形成时代为191±2 Ma,其锆石Hf同位素组成变化范围较大,εHf(t)值介于-11.26~-2.51,主要为富集地幔部分熔融产物。综合本文及前人已有研究结果,认为~190 Ma的早侏罗世早期秦岭地区早中生代碰撞造山过程已经结束,区域开始逐渐进入板内伸展构造演化阶段。     

广西隆安都结剖面下石炭统都安组上部鲕粒类型及其地质意义

鲕粒是一类特殊的沉积颗粒,为古气候和古海洋环境的重要指示器。为了深入认识此类特殊颗粒的成因机制、形成环境及地质意义,对广西隆安地区都结剖面下石炭统都安组上部含鲕粒地层开展了古生物学、沉积学和岩相学研究。研究区共识别出5种主要的鲕粒类型:放射状纹层鲕粒(O1)、规则同心放射状纹层鲕粒(O2)、不规则同心放射状纹层鲕粒(O3)、泥晶鲕粒(O4-A和O4-B)和复合鲕粒(O5)。各类鲕粒的显微组构和沉积环境指示其具有不同的形成过程,其中水动力条件影响和控制着鲕粒的发育和分布情况。研究区含鲕粒地层形成于维宪期末-谢尔普霍夫期,恰好对应早石炭世晚期冰川作用的开始。受冰川作用影响,全球海平面频繁波动,研究区地处低纬度地区并以浅滩和潮坪沉积环境为主,为鲕粒的形成提供了适宜的水体条件,即温暖、动荡的浅水环境。此外,含鲕粒岩层内广泛发育钙质微生物和微生物席,说明微生物活动在研究区较为常见,可能与鲕粒的形成过程具有一定的关联。     

Field study on the behavior of pre-bored grouted planted pile with enlarged grout base

This paper presents the results of field tests performed to investigate the compressive bearing capacity of pre-bored grouted planted (PGP) pile with enlarged grout base focusing on its base bearing capacity. The bi-directional O-cell load test was conducted to evaluate the behavior of full scale PGP piles. The test results show that the pile head displacements needed to fully mobilize the shaft resistance were 5.9% and 6.4% D (D is pile diameter), respectively, of two test piles, owing to the large elastic shortening of pile shaft. Furthermore, the results demonstrated that the PHC nodular pile base and grout body at the enlarged base could act as a unit in the loading process, and the enlarged grout base could effectively promote the base bearing capacity of PGP pile through increasing the base area. The normalized base resistances (unit base resistance/average cone base resistance) of two test piles were 0.17 and 0.19, respectively, when the base displacement reached 5% D_b (D_b is pile base diameter). The permeation of grout into the silty sand layer under pile base increased the elastic modulus of silty sand, which could help to decrease pile head displacement under working load.

     

Pore structure and heterogeneity of shale gas reservoirs and its effect on gas storage capacity in the Qiongzhusi Formation

Fine characterization of pore systems and heterogeneity of shale reservoirs are significant contents of shale gas reservoir physical property research.The research on micro-control factors of low productivity in the Qiongzhusi Formation(Fm.)is still controversial.The lower Cambrian Qiongzhusi Fm.in the Qujing,Yunnan was taken as the object to investigate the influence of mineral compositions on the phys-ical properties of the reservoir and the heterogeneity of shale,using the algorithm to improve the char-acterization ability of Atomic Force Microscopy(AFM).The results showed that:(1)The pores are mainly wedge-shaped pores and V-shaped pores.The pore diameter of the main pore segment ranges from 5 to 10 nm.Mesopores are mainly developed in the Qiongzhusi Fm.shale in Well QD1,with the average pore diameter of 6.08 nm.(2)Microscopic pore structure and shale surface properties show strong hetero-geneity,which complicates the micro-migration of shale gas and increases the difficulty of identifying high-quality reservoirs.(3)The increase of clay mineral content intensifies the compaction and then destroys the pores.Conversely,brittle minerals can protect pores.The support and protection of brittle minerals to pores space depend on their content,mechanical properties and diagenesis.(4)Compression damage to pores,large microscopic roughness and surface fluctuations and strong pore structure heterogeneity are the reasons for the poor gas storage capacity of the Qiongzhusi Fm.,which will lead to poor productivity in the Qiongzhusi Fm.     

江西省山地风场风速订正方法研究

利用气象站、探空及NASA再分析资料,对江西省4县山地风场的12座测风塔风速进行订正研究。研究结果表明:测风塔与气象站风速数据相关性较低,相关系数一般远小于0.45;测风塔与探空资料的风速相关系数可达到0.6以上,最高可达到0.8;NASA再分析资料可以作为江西山地风场风速订正参证数据,其与测风塔风速数据相关性较高,相关系数可达到0.54～0.77,大多数测风塔相关系数可达0.7左右。海拔高度小于1000 m的测风塔与NASA 50 m风速的相关系数明显高于其与NASA 850 hPa风速的相关系数,高度为1000—1200 m的测风塔与NASA 50 m风速和与NASA 850 hPa风速的相关系数相差不明显,高度大于1200 m的测风塔与NASA 850 hPa风速的相关系数明显大于其与NASA 50 m风速的相关系数。比值法订正效果略好于线性回归法的,订正后的风功率密度总体偏大。