Microscopic investigation on bonding fracture of biocemented sand from novel in situ brazil splitting tests     

Ma  Guoliang  Fang  Qingyun  Xiao  Yang  Chu  Jian  Liu  Hanlong 《Acta Geotechnica》2022,17(11):4935-4951

Acta Geotechnica - The failure mechanism of biocemented sand has been largely speculated based on scanning electron microscopy images of biocemented sand after mechanical tests. However, some...  相似文献   

Effect of groundwater on the ecological water environment of typical inland lakes in the Inner Mongolian Plateau          下载免费PDF全文

Chu Yu  Li-jie Wu  Yi-long Zhang  Xiu-ya Wang  Zhan-chuan Wang  Zhou Zhang 《地下水科学与工程》2022,10(4):353-366

To explore the causes of the ecological environment deterioration of lakes in the Inner Mongolia Plateau, this study took a typical inland lake Daihai as an example, and investigated the groundwater recharge in the process of lake shrinkage and eutrophication. Using the radon isotope (²²²Rn) as the main means of investigation, the ²²²Rn mass balance equation was established to evaluate the groundwater recharge in Daihai. The spatial variability of ²²²Rn activity in lake water and groundwater, the contribution of groundwater recharge to lake water balance and its effect on nitrogen and phosphorus pollution in lake water were discussed. The analysis showed that, mainly controlled by the fault structure, the activity of ²²²Rn in groundwater north and south of Daihai is higher than that in the east and west, and the difference in lithology and hydraulic gradient may also be the influencing factors of this phenomenon. The ²²²Rn activity of the middle and southeast of the underlying lake is greater, indicating that the ²²²Rn flux of groundwater inflow is higher, and the runoff intensity is greater, which is the main groundwater recharge area for the lake. The estimated groundwater recharge in 2021 was 3 017×10⁴ m³, which was 57% of the total recharge to the lake, or 1.6 times and 8.1 times that of precipitation and surface runoff. The TN and TP contents in Daihai have been rising continuously, and the average TN and TP concentrations in the lake water in 2021 were 4.21 mg·L^?1 and 0.12 mg·L^?1, respectively. The TN and TP contents entering the lake with groundwater recharge were 6.8 times and 8.7 times above those of runoff, accounting for 87% and 90% of the total input, respectively. The calculation results showed that groundwater is not only the main source of recharge for Daihai, but also the main source of exogenous nutrients. In recent years, the pressurized exploitation of groundwater in the basin is beneficial in increasing the groundwater recharge to the lake, reducing the water balance difference of the lake, and slowing down the shrinking degree of the lake surface. However, under the action of high evaporation, nitrogen and phosphorus brought by groundwater recharge would become more concentrated in the lake, leading to a continuous increase in the content of nutrients and degree of eutrophication. Therefore, the impact of changes in regional groundwater quantity and quality on Daihai is an important issue that needs further assessment.  相似文献   

Application of frequency division inversion in the prediction of heterogeneous natural gas hydrates reservoirs in the Shenhu Area,South China Sea     

Shu-yu Wu  Jun Liu  Hua-ning Xu  Chang-ling Liu  Fu-long Ning  Hong-xian Chu  Hao-ran Wu  Kai Wang 《China Geology》2022,5(2):251-266

Drilling results suggest that the thickness of natural gas hydrates (NGHs) in the Shenhu Area, South China Sea (SCS) are spatially heterogenous, making it difficult to accurately assess the NGHs resources in this area. In the case that free gas exists beneath hydrate deposits, the frequency of the hydrate deposits will be noticeably attenuated, with the attenuation degree mainly affected by pore development and free gas content. Therefore, the frequency can be used as an important attribute to identify hydrate reservoirs. Based on the time-frequency characteristics of deposits, this study predicted the spatial distribution of hydrates in this area using the frequency division inversion method as follows. Firstly, the support vector machine (SVM) method was employed to study the amplitude versus frequency (AVF) response based on seismic and well logging data. Afterward, the AVF response was introduced as independent information to establish the nonlinear relationship between logging data and seismic waveform. Then, the full frequency band information of the seismic data was fully utilized to obtain the results of frequency division inversion. The inversion results can effectively broaden the frequency band, reflect the NGHs distribution, and reveal the NGHs reservoirs of two types, namely the fluid migration pathway type and the in situ self-generation self-storage diffusion type. Moreover, the inversion results well coincide with the drilling results. Therefore, it is feasible to use the frequency division inversion to predict the spatial distribution of heterogeneous NGHs reservoirs, which facilitates the optimization of favorable drilling targets and is crucial to the resource potential assessment of NGHs.©2022 China Geology Editorial Office.  相似文献   

西藏山南努日超大型钨多金属矿床岩浆演化对区域成矿作用指示     

闫国强  王欣欣  黄勇  刘洪  黄瀚霄  田恩源  赖杨  赵晋 《地质学报》2018,92(10):2138-2154

努日超大型多金属矿床是近年来冈底斯成矿带发现的首例白钨矿矿床,通过对矿区不同产状、岩性的岩浆岩开展主量元素、微量元素、稀土元素、锆石U- Pb年代学、Re- Os同位素、Sr- Nd- Pb- Hf同位素等综合研究,研究结果表明：努日矿区岩浆岩演化序列为石英闪长玢岩（93.42±0.76 Ma）→安山岩（92.04±0.71 Ma）→黑云母花岗岩（50.46±0.56 Ma）→花岗闪长斑岩（24.83±0.21 Ma）,从高钾钙碱性到钙碱性系列均有分布,其中石英闪长玢岩含SiO2 57.19%～58.23 %, K2O 1.71%～2.2%, 总碱含量高（5.28%～5.77%）, 含A12O3 14.14%～16.45%,CaO含量中等(2.33%～4.11%),里特曼指数(σ)为1.79～2.07,铝指数(A/CNK)为0.77～0.82,Mg#指数47.19～49.51, 岩石富集大离子亲石元素Rb、U、Pb、Ba、Th,轻重稀土分异明显,LREE/HREE为10.25～11.07,具有弱的Ce异常,相对较低的87Sr/86Sr初始比值(0.7039～0.706),具有埃达克岩特征;安山岩含SiO2 54.17%～60.27%, K2O 1.78%～2.25%, A12O3 17.89%～22.65%。里特曼指数σ为1.32～2.34,铝指数(A/CNK)为0.91～1.54、Mg#指数48.14～52.04, 岩石富集大离子亲石元素Rb、U、Ba、Th,轻重稀土分异明显,LREE/HREE为986～1694,具有明显的的Eu负异常,为正常岛弧岩浆岩特征;黑云母花岗岩含SiO2 64.90%～66.12 %, K2O 2.31%～23.86%, 总碱含量高(6.47%～7.01%), 含A12O3 15.52%～16.15%、CaO含量中等(2.33%～4.11%),里特曼指数σ为1.45～2.17,铝指数(A/CNK)为0.93～1.02,Mg#指数28.49～36.55, 岩石富集大离子亲石元素Rb、U、Pb、Ba、Th,轻重稀土分异明显,LREE/HREE为6.26～7.29,具有强的Eu负异常,小于大陆地壳值的87Sr/86Sr初始比值(0.704488～0.704584),具有岛弧岩浆岩特点;花岗闪长斑岩含SiO2 59.12%～74.97%, K2O 0.83%～3.67%, 总碱含量高(2.77%～6.89%),含A12O3 11.31%～17.06%、CaO含量中等(5.32%～6.22%),里特曼指数σ为0.24~2.64,铝指数(A/CNK)为0.75~0.93,Mg#指数35.11～51.57, 岩石富集大离子亲石元素Rb、U、Ba、Th,轻重稀土分异明显,LREE/HREE为9.866～16.93,具有弱的Eu负异常,其87Sr/86Sr初始比值(0.705745～0.706073),稍小于大陆地壳,其εHf(t)为2.76716～8.66174,暗示来源于新生的大陆地壳,具有埃达克质岩特点。黄铜矿Re- Os同位素特征显示矿区存在三期矿化事件,与矿集区内成矿事件吻合较好,对于指导下一步矿集区寻找不同时代成矿事件具有重要意义。  相似文献   

Crowdsourcing photograph locations for debris flow hot spot mapping     

Hone-Jay Chu  Yi-Chin Chen 《Natural Hazards》2018,90(3):1259-1276

This study shows the feasibility of obtaining hazardous hot spot information on landslide and debris flow from crowdsourced data. Historical hazard or disaster photographs were voluntarily uploaded by the public to a Web photograph album. A total of 2245 hazard photographs from 1973 to 2015 were crowdsourced, and each photograph was tagged with geographical coordinates. After the removal of outliers, 96% of the photograph points were found within the 4 km potential debris flow buffer of existing databases, and none was found along the steep slopes with a mean of 14°. The photograph hot spot analysis using local Moran’s I or G _i * was identified statistically significant without subjective judgment. The DBSCAN model was also used to detect hot spot clusters effectively. The model parameters were nearly automatically generated on the basis of the count plot and the nearest neighbor distance graph. The results of these approaches were generally consistent with the hazardous hot spot maps and strongly related to central and southern Taiwan from the crowdsourced photograph data. Results reveal that the hot spot areas are found in areas with faults and near the potentially weak and fractured rocky regions. The majority of the landslides occur near the fault line because the strong ground motions triggered by an earthquake propagated along the fault rupture plane. Hot spot mapping using crowdsourced data can be used to estimate where debris flow will frequently occur and show how large the debris flow will be. Potentially hazardous areas can be effectively determined by the hot spot analysis of crowdsourced data.  相似文献   

基于多种方法的土壤重金属污染风险评价对比——以江汉平原典型场区为例          下载免费PDF全文

陈江军  刘波  蔡烈刚  王国强  殷科  陈海波  李智民 《水文地质工程地质》2018,(6):164-164

以江汉平原典型场区周边农田土壤为研究对象,分析了土壤重金属元素Cd、Pb、As、Hg的总量和赋存形态特征,选用修正单项污染指数法、潜在生态风险指数法、风险评估编码法(RAC)和次生相与原生相比值法(RSP)四种评价方法开展了土壤重金属的污染风险评价,并对评价结果进行了对比讨论。分析结果表明:（1）基于总量的两种方法对比,潜在生态风险指数法优于修正单项污染指数法。（2）基于形态的两种方法对比,RAC法的评价结果比RSP法更为合理。（3）基于总量和形态方法对比,潜在生态风险指数法和RAC法各有其优缺点,潜在生态风险指数法能直观反映重金属在土壤中的富集信息和环境危害性,而RAC法则可以利用形态来阐明重金属在土壤环境中的行为特性和生态活性。因此,在进行土壤重金属污染风险评价时,综合考虑重金属种类、累积程度、生物毒性和生物可利用性等参数指标,才能更加科学准确地评估重金属在土壤中的环境风险。综合上述评价结果,江汉平原典型场区周边农田土壤重金属元素Pb、As污染程度较低,对周边环境无影响;重金属元素Hg累积程度不高,但由于其具有较高的生物毒性,对周边环境存在潜在威胁;重金属元素Cd是研究区最主要的污染因子,对周边环境影响大,亟需采取相应措施减轻Cd带来的风险。  相似文献   

Evaluation and correction of the TRMM 3B43V7 and GPM 3IMERGM satellite precipitation products by use of ground-based data over Xinjiang,China   总被引：2，自引：0，他引：2  

Xinyu Lu  Ming Wei  Guoqiang Tang  Yingxin Zhang 《Environmental Earth Sciences》2018,77(5):209

Satellite retrieval of precipitation is a great challenge in arid regions where light precipitation prevails. To improve the accuracy of satellite precipitation products in Xinjiang, which is the driest region in China, this study first evaluated the performance of two widely used monthly satellite products from April 2014 to August 2017. The first was the Tropical Rainfall Measuring Mission (TRMM) 3B43 version 7 (hereafter 3B43V7), and the second was the Integrated Multi-Satellite Retrievals for the Global Precipitation Measurement (GPM) mission (IMERG) (hereafter 3IMERGM). The 3IMERGM product was then corrected by a stepwise regression model using topographic variables derived from digital elevation model (DEM). A comparison between satellite estimates and in situ measurements indicates that both 3B43V7 and 3IMERGM overestimate precipitation overall, but that 3IMERGM performs better than 3B43V7. The relative biases (RB) of 3B43V7 and 3IMERGM were found to be 10.24 and 7.76%, respectively. The correlation coefficient (CC) between 3IMERGM and the gauges is 0.68, which is higher than the CC observed (i.e., 0.62) between 3B43V7 and the gauges. To comprehensively evaluate the performance of the corrected model, a tenfold cross-validation method was used. The results showed that the corrected 3IMERGM (C-3IMERGM) performed much better than 3IMERGM. Specifically, CC was increased from 0.68 to 0.73, and RB is decreased from 7.76 to ? 1.65%. Furthermore, C-3IMERGM achieves a better precipitation distribution than the uncorrected satellite product and even than scarce gauge measurements. The actual spatial pattern of precipitation represented that the precipitation bands in the Kunlun Mountains located in southern Xinjiang were captured by C-3IMERGM, but missed by the other products.  相似文献   

北祁连玉石沟蛇绿岩形成时代的上限——来自正长岩锆石U-Pb定年的证据     

王国强  李向民  余吉远  唐卓  朱涛  潘峰  张越  卜涛 《地质通报》2018,37(4):532-537

北祁连地区玉石沟蛇绿岩以发育较完整和典型的蛇绿岩岩石组合而备受关注。对侵入于玉石沟蛇绿岩中的正长岩进行LA-ICP-MS锆石U-Pb定年,获得正长岩的结晶年龄为522.7±5.3Ma,属早寒武世。这是北祁连地区最早的碱性侵入岩浆活动记录。该年龄的获得限定了玉石沟蛇绿岩形成时代的上限,应不晚于522Ma,即玉石沟蛇绿岩所代表的洋盆的发育扩张过程至少在该时限前已结束。  相似文献   

苏拉威西岛北部左旋走滑与俯冲后撤的动力学分析     

张健  董淼  姜程浩  方桂  褚伟  何雨蓓 《地质学报》2023,97(1):1-15

苏拉威西岛北部属于马鲁古海板块,其主体是北苏拉威西海沟俯冲带与帕卢-科洛左旋走滑断裂所围限的岛北支和岛东支。大约5 Ma前,苏拉群岛沿Sorong断层与苏拉威西岛东支碰撞,导致北苏拉威西海沟俯冲后撤,引起了岛北支顺时针旋转约20°～25°,同时,西侧的帕卢-科洛断层发生了约4 cm/a的左旋走滑。本文利用综合地球物理方法,计算了该区三维温度、速度、黏性特征,认为：苏拉威西岛北部在左旋走滑、俯冲后撤过程中,地壳以脆性变形为主,但由于北苏拉威西海沟俯冲带在地壳内形成南向倾斜的软弱层,Moho面和地形“镜像”区域内形成脆、韧变形共存的组合。地幔变形为韧性变形,深度约100 km的上地幔低速流变层是地幔韧性变形的主控层位。在周边板块边界不断移动的动力学背景中,苏拉威西岛北部在地壳尺度以收缩-伸展变形为主,在岩石圈尺度以旋转变形为主。  相似文献   

利用深度学习模型智能识别地下排水管道缺陷     

王大成  谭军辉  彭述刚  钟镇声  陈国强  李国桥 《测绘通报》2021,(10):141-145

排水管道健康状况直接影响整个城市的排水效果,CCTV检测作为目前最为常见的排水管道健康状况检测方法,仍存在自动化程度不高、工作效率低下、严重依赖人工经验等问题。为解决以上问题,本文将当前先进的深度学习技术与地下排水管道缺陷检测技术相结合,提出了一种基于深度学习模型的地下排水管道缺陷智能识别技术。同时,将管道缺陷智能识别与管道检测工作流程紧密结合,实现城市排水管道检测报告的快速自动生成等功能,从而大大提高排水管道缺陷的检测效率。  相似文献