Provenance Study of Fe–Ti Oxide Minerals in the Quaternary Sediments in Yichang Area and Its Implication of Formation Time of the Yangtze Three Gorges, China

The Three Gorges are considered to be critical to understand the formation of Yangtze River. Recent research results suggest that the Yangtze Three Gorges was created during the Quaternary but the exact time is debatable. Fe–Ti oxide minerals are seldom used to study sediment provenance, expecially using scanning electron microscopy(SEM), and energy dispersive spectrometer(EDS). In this study, the provenance of Quaternary sediments in Yichang area, which is located to the east of the Yangtze Three Gorges, was investigated by using SEM and EDS to research Fe–Ti oxides. The Panzhihua vanadium titanomagnetite and Emeishan basalt outcrop are located to the west of the Three Gorges. Further, the materials from them are observed in the Quaternary sediments of Yichang area. Fe–Ti oxide minerals from the Huangling granite are observed in the Yunchi and Shanxiyao Formations, which were formed before 0.75 Ma B.P., whereas Fe–Ti oxide minerals from the Huangling granite, Panzhihua vanadium titanomagnetite, and Emeishan basalt are observed in the riverbed and fifth-terrace sediments of the Yangtze River, which were formed after 0.73 Ma B.P.. Thus, we can infer that the Three Gorges formed after the deposition of the Shanxi Formation and before the fifth-terrace; i.e., 0.75–0.73 Ma B.P..     

天津滨海新区抽水引起地面沉降现场试验研究

在天津滨海新区中新生态城服务中心开展了承压含水层抽水引起地面沉降的现场试验,采用振弦式孔隙水压力传感器和一孔多标数据采集器实时监测孔隙水压力和分层标的变化,分析了土体的变形性质和分层沉降的规律。试验结果表明,黏土层变形明显滞后于承压含水层水位的变化,以塑性变形为主且存在蠕变现象,而砂层既存在弹性变形,也存在一定的塑性变形和蠕变性。短期抽取地下水会使抽水井附近承压含水层上覆土体出现上小下大的沉降规律,且最大沉降出现在有明显孔隙水压力变化的土层顶板位置。     

重塑压实黏土Ⅰ型断裂试验研究

为探究重塑黏土Ⅰ型断裂韧度,本文在前人研究基础上,通过对应变控制式直剪仪进行改造,消除了传统三点弯曲试验对土体断裂韧度测试所带来的影响,研制了土体Ⅰ型断裂韧度测试仪,并对重塑黏土进行了一系列试验。试验结果表明:新研制出的土体Ⅰ型断裂韧度测试仪具有较好的可靠性;对具有相同物理状态的试样,U 形裂纹试样的断裂韧度最大,三角形裂纹试样的断裂韧度最小;试样的含水率和干密度其断裂韧度KIC具有显著影响,随含水率增加,断裂韧度呈现先增后减的变化规律,而随干密度增加,断裂韧度几乎线性增加;在试验采用的加载速率范围内,加载速率对断裂韧度的影响较小。     

Probabilistic calibration of a coupled hydro-mechanical slope stability model with integration of multiple observations

Multiple types of responses, such as displacements, ground water level, pore water pressures, water contents, etc., are usually measured in comprehensive monitoring programmes for rainfall-induced landslide prevention. In this study, a probabilistic calibration method for coupled hydro-mechanical modelling of slope stability is presented with integration of multiple types of measurements. A numerical example of a soil slope under rainfall infiltration is illustrated to compare the effects of single and multiple types of responses on parameter estimation and model calibration. The results show that the soil parameters can be estimated with less uncertainty and total uncertainty bounds are narrower with multiple types of responses than with a single type of response. Model calibration based on multiple types of responses can compromise different responses and hence the means and standard deviations of model error are the smallest. A feasible correlation coefficient between soil modulus and permeability can be obtained from model calibration with multiple types of responses and single type of response as long as the responses include displacement data.     

碘化氨除锡后封闭酸溶-电感耦合等离子体质谱测定锡矿石中的共生和伴生元素

锡矿石是难分解的矿物,主要存在形式是锡石(SnO_2),且共生和伴生元素多,常用的酸溶方法几乎不能溶解SnO_2,从而给锡矿石中的共生与伴生元素的准确测定带来困难。本文基于碘化氨在较低温度下熔融可产生无水状态的碘化氢,利用碘化氢的酸性和氨的还原性分解SnO_2,使Sn呈SnI_4升华分离的原理处理锡矿石。实验中以高纯铂丝作催化剂,加入碘化铵在450℃的马弗炉中分解锡矿石30 min,使得Sn以SnI_4形式挥发,除锡率达到98%以上,再用2 mL氢氟酸和1 mL硝酸封闭溶解残渣,电感耦合等离子体质谱测定钴镍铜铌钽钍铀等24个共生和伴生元素。元素检出限在0. 001～2. 9μg/g之间,90%以上元素的相对标准偏差(RSD)小于5%,相对误差小于10%。本方法解决了锡矿石难分解的问题,可测定共存金属元素,也适合测定Sn含量在1. 27%～62. 49%之间的锡矿石中的微量和痕量元素及锡精矿中的微量元素。     

Effect of loading duration on uncertainty in creep analysis of clay

Some studies suggest that creep parameters should be determined using a greater quantity of creep test data to provide more reliable prediction regarding the deformation of soft soils. This study aims to investigate the effect of loading duration on model updating. One‐dimensional consolidation data of intact Vanttila clay under different loading durations collected from the literature is used for demonstration. The Bayesian probabilistic method is used to identify all unknown parameters based on the consolidation data during the entire consolidation process, and their uncertainty can be quantified through the obtained posterior probability density functions. Additionally, the optimal models are also determined from among 9 model candidates. The analyses indicate that the optimal models can describe the creep behavior of intact soft soils under different loading durations, and the adopted method can evaluate the effect of loading duration on uncertainty in the creep analysis. The uncertainty of a specific model and its model parameters decreases as more creep data are involved in the updating process, and the updated models that use more creep data can better capture the deformation behavior of an intact sample. The proposed method can provide quantified uncertainty in the process of model updating and assist engineers to decide whether the creep test data are sufficient for the creep analysis.     

粗粒碎屑岩砾石定向性定量表征方法及应用

砾石定向性可用于辅助判断粗粒沉积物沉积环境的介质动力性质与强度。在岩芯图像分析与测量的基础上,运用砾石长轴视倾角玫瑰花图中任意相邻三个小扇形的半径之和的最大值（参数a）和小扇形半径大小偏离程度（参数σ）对玛湖地区百口泉组砂砾岩中砾石定向性进行等级划分和定量表征。通过该方法的应用,建立了该区不同级别砾石定向性的定量划分方案:有明显定向性（a大于35%且σ大于4）、有一定定向性（a大于35%且σ小于4）、有模糊定向性（a小于35%且σ大于4）、定向性杂乱（a小于35%且σ小于4）。并对研究区典型季节性辫状河道和暂时性辫状河道的定向性进行了实测,结果表明季节性辫状河道中σ为4.8~8.13,a为40%~62%,而暂时性辫状河道中σ小于4,a小于35%。该方法能够有效表征砾石定向性,并为沉积环境判断提供依据。     

鄂尔多斯盆地中部马五7亚段颗粒滩沉积特征及空间分布

鄂尔多斯盆地中部马家沟组地层蕴含丰富的油气资源,以马五₇亚段为主要储集层位的盐下碳酸盐岩油气勘探近期取得了重要突破。基于钻井、测录井、岩芯及薄片等资料,对盆地中部马五₇亚段颗粒滩沉积特征、纵横向展布规律进行综合分析,进而探讨了研究区沉积古地理格局及其颗粒滩发育控制因素。结果表明:研究区马五₇亚段主要由晶粒白云岩及各类型颗粒白云岩构成,纵向上发育潟湖-颗粒滩-灰泥丘-台坪、潟湖-颗粒滩-滩间海-颗粒滩、潟湖-颗粒滩-灰泥丘三种沉积相序,颗粒滩位于向上变浅旋回的中上部,且常与微生物丘构成丘滩复合体建造,具有良好的储集意义。横向上,马五₇亚段发育两套较大规模的颗粒滩,层位稳定且连续性较好,整体表现为中西部厚而东部较薄的特征,平面上则呈南北向发育并沿东部凹陷环带状分布。研究区沉积规律表明马五₇亚段相对缺乏潮坪相沉积特征,推测其沉积环境更符合局限-蒸发台地。沉积期海平面的频繁变化控制了滩体发育规模及其垂向叠置样式,区内西高东底的古构造格局及其内部的微地貌起伏则决定了马五₇颗粒滩平面分布的差异性。     

Science and Technology of Delimitation of Continental Shelf and Its Application in Maritime Silk Road Cooperation*

Delimitation of the continental shelf is an emerging interdisciplinary discipline in the field of international marine science and technology. It uses the scientific and technological means to expand the jurisdiction of coastal states based on the international rules of the 《United Nations Convention on the Law of the Sea》. Therefore, it is related to the marine sovereignty rights and interests of a country and also a hot topic of science and technology that all countries have competed to develop. China has launched the research in this field simultaneously with the world's maritime powers, and formed its innovative advantages in such aspects as geological models, detection techniques and delimitation systems in the delimitation of continental shelf, which have become the brand new ties for China's cooperation with foreign countries in marine science and technology, and also the important field in the maritime silk road cooperation in the 21^st century. This paper introduced the basic principles and methods in the delimitation of continental shelf beyond 200 nautical miles (370 km), progress in the delimitation of the global continental shelf, and China's innovative science and technology as well as its application in maritime Silk Road cooperation, and provided the prospect of the future scientific and technological cooperation with foreign countries and development in this filed. And it was suggested China should develop the scientific and technological cooperation on the delimitation of the continental shelf along the Silk Road, promote the scientific and technological development of the delimitation of the continental shelf in China, and enhance China's influence and voice in international ocean affairs.