Uncertainty quantification of landslide runout motion considering soil interdependent anisotropy and fabric orientation

Landslides - Natural soils often exhibit an anisotropic fabric pattern as a result of soil deposition, weathering, or filling. This paper aims to investigate the effect of soil interdependent...     

Movement process,geomorphological changes,and influencing factors of a reactivated loess landslide on the right bank of the middle of the Yellow River,China

Landslides - According to local villagers, the main Beiguo landslide on the Heyang Loess Tableland in China occurred several decades ago (the specific time is unknown). After the initial occurrence...     

Characteristics and generation mechanisms of key infrared radiation signals during damage evolution in sandstone

Acta Geotechnica - Infrared radiation count (IRC) is considered as an indicator for damage evolution of rocks. This new indicator links damage intensity and corresponding infrared radiation...     

Kaolin-nucleation-based biotreated calcareous sand through unsaturated percolation method

Acta Geotechnica - Ocean development is an effective and practical way to address resource issues, such as food, fuel, and land shortage. The current work proposed using kaolin-based biocement to...     

Transformation of ammonium nitrogen and response characteristics of nitrifying functional genes in tannery sludge contaminated soil

High concentrations of ammonium nitrogen released from tannery sludge during storage in open air may cause nitrogen pollution to soil and groundwater. To study the transformation mechanism of NH₄⁺-N by nitrifying functional bacteria in tannery sludge contaminated soils, a series of contaminated soil culture experiments were conducted in this study. The contents of ammonium nitrogen (as NH₄⁺-N), nitrite nitrogen (as NO₂^?-N) and nitrate nitrogen (as NO₃^?-N) were analyzed during the culture period under different conditions of pollution load, soil particle and redox environment. Sigmodial equation was used to interpret the change of NO₃^?-N with time in contaminated soils. The abundance variations of nitrifying functional genes (amoA and nxrA) were also detected using the real-time quantitative fluorescence PCR method. The results show that the nitrification of NH₄⁺-N was aggravated in the contaminated silt soil and fine sand under the condition of lower pollution load, finer particle size and more oxidizing environment. The sigmodial equation well fitted the dynamic accumulation curve of the NO₃^?-N content in the tannery sludge contaminated soils. The Cr(III) content increased with increasing pollution load, which inhibited the reproduction and activity of nitrifying bacteria in the soils, especially in coarse-grained soil. The accumulation of NO₂^?-N contents became more obvious with the increase of pollution load in the fine sand, and only 41.5% of the NH₄⁺-N was transformed to NO₃^?-N. The redox environment was the main factor affecting nitrification process in the soil. Compared to the aerobic soil environment, the transformation of NH₄⁺-N was significantly inhibited under anaerobic incubation condition, and the NO₃^?-N contents decreased by 37.2%, 61.9% and 91.9% under low, medium and high pollution loads, respectively. Nitrification was stronger in the silt soil since its copy number of amoA and nxrA genes was two times larger than that of fine sand. Moreover, the copy numbers of amoA and nxrA genes in the silt soil under the aerobic environment were 2.7 times and 2.2 times larger than those in the anaerobic environment. The abundance changes of the amoA and nxrA functional genes have a positive correlation with the nitrification intensity in the tannery sludge-contaminated soil.     

Indication of hydrogen and oxygen stable isotopes on the characteristics and circulation patterns of medium-low temperature geothermal resources in the Guanzhong Basin,China

Guanzhong Basin is a typical medium-low temperature geothermal field mainly controlled by geo-pressure in the west of China.The characteristics of hydrogen and oxygen isotopes were used to analyze the flow and storage modes of geothermal resources in the basin.In this paper,the basin was divided into six geotectonic units,where a total of 121 samples were collected from geothermal wells and surface water bodies for the analysis of hydrogen-oxygen isotopes.Analytical results show that the isotopic signatures of hydrogen and oxygen throughout Guanzhong Basin reveal a trend of gradual increase from the basin edge areas to the basin center.In terms of recharge systems,the area in the south edge belongs to the geothermal system of Qinling Mountain piedmont,while to the north of Weihe fault is the geothermal system of North mountain piedmont,where the atmospheric temperature is about 0.2℃-1.8℃in the recharge areas.The main factors that affect the geothermal waterδ18O drifting include the depth of geothermal reservoir and temperature of geothermal reservoir,lithological characteristics,water-rock interaction,geothermal reservoir environment and residence time.Theδ18O-δD relation shows that the main source is the meteoric water,together with some sedimentary water,but there are no deep magmatic water and mantle water which recharge the geothermal water in the basin.Through examining the distribution pattern of hydrogen-oxygen isotopic signatures,the groundwater circulation model of this basin can be divided into open circulation type,semi-open type,closed type and sedimentary type.This provides some important information for rational exploitation of the geothermal resources.     

板钉连接CFST柱-RC梁节点梁端塑性铰区受力性能数值模拟

建立竖板-栓钉连接钢管混凝土（CFST）柱-钢筋混凝土（RC）梁节点试件（SSJD）拟静力加载试验有限元模型,并在节点损伤情况、梁端荷载-位移曲线等数值模拟结果与试验结果吻合较好的基础上,进一步开展了RC梁混凝土强度、配筋率ρ_s和连接竖板长度L_b及界面连接情况等对CFST柱-RC梁节点梁端塑性铰区域力学性能的影响。研究结果表明,RC梁混凝土强度对试件SSJD塑性铰区域受力性能的影响较小;适筋范围内RC梁配筋率增加可适当提高试件SSJD承载力和延性;随着连接竖板长度的增加,梁端塑性铰区域外移,梁破坏荷载增大;本研究给出的RC梁与CFST柱之间的界面抗剪承载力模拟值与计算值吻合较好,可用于界面抗剪设计。     

Palynological constraints on the age of the Mississippi Valley-type Changdong Pb-Zn deposit,Sanjiang belt,West China

Mississippi Valley-type(MVT)Pb-Zn deposits serve as the world’s major supply of Pb-Zn resources.However,the age constraint of MVT Pb-Zn deposits has long been a big challenge,due to the lack of minerals that are unequivocally related to ore deposition and that can be used for radioisotopic dating.Here we show sporopollens can provide useful chronological information on the Changdong MVT Pb-Zn deposit in the Simao basin,Sanjiang belt,West China.The Pb-Zn ores in the Changdong deposit are hosted by internal sediments in paleo-karst caves of meteoric origin.Sphalerite and galena occur as replacements of carbonate minerals and void infillings in the internal sediments.The relations suggest that the Pb-Zn mineralization occurred after the deposition of the internal sediments.A palynological assemblage mainly composed of angiosperm pollen dominated by Castanea,Quercus,and Carya and fern spores dominated by Polypodiaceae,Pteris,and Athyriaceae was identified.These pollen and spores place the ore-hosting internal sediments and the Changdong paleo-karst at early to middle Oligocene.Consequently,the Changdong Pb-Zn deposit must have formed after the early Oligocene(~34 Ma).These age constraints,together with the geological characteristics,indicate that the Changdong Pb-Zn deposit is a paleo-karst-controlled MVT deposit related to fold-thrust systems in the Sanjiang belt.The Changdong deposit is similar to other MVT Pb-Zn deposits in the northern part of the Sanjiang belt,making it possible to extend this Pb-Zn belt 500 km further to the South.Results presented here highlights the potential of sporopollens in dating the age of MVT deposits related to paleo-karst formation in young orogenic belts.     

The first extra-large helium-rich gas field identified in a tight sandstone of the Dongsheng Gas Field,Ordos Basin,China

Science China Earth Sciences - Helium gas is a scarce but important strategic resource, which is usually associated with natural gas. Presently, only one extra-large helium-rich gas field has been...     

川南威远—泸州页岩气井区奥陶系顶部观音桥组岩相和沉积环境

上扬子地区四川盆地南部威远—泸州地区上奥陶统凯迪阶五峰组和志留系底部兰多维列统龙马溪组黑色笔石页岩沉积于滞留缺氧海底且富含有机质,是页岩气的主产层位,介于五峰组和龙马溪组之间的奥陶系顶部赫南特阶观音桥组通常是含腕足类以及三叶虫的灰岩沉积,其化石组成是冈瓦纳冰川事件最盛期在低纬度陆表海区的产物,岩石学微相特征研究能进一步诠释当时海底沉积环境。本文根据威远地区的W2、W4H10井,泸州地区的L2井、L4井、 L5井、 L6井、 L7井、 L8井、 L9井观音桥组微相鉴定识别生物多样性,除常见的Hirnantia腕足动物群、三叶虫Dalmanitina等壳相化石外,还出现海百合、腹足类Homotoma、双壳类、海绵动物碎片和虫管遗迹化石Chondrites(丛藻迹),其化石组成记录了该层位的生物多样性。观音桥组沉积时该区海底富氧环境有利于底栖动物生存,远岸区海底水动力弱,化石粒度偏细且部分化石破碎程度高,未见大量复体珊瑚和钙藻等典型暖水区化石,反映出远岸相观音桥组海底水温可能偏低。