土工格栅蠕变特性的试验研究及粘弹性本构模型   总被引：12，自引：5，他引：7  

栾茂田  肖成志  杨庆  裴建军 《岩土力学》2005,26(2):187-192

土工格栅的蠕变特性是影响土工格栅加筋支挡结构长期工作性能的重要因素。通过实验室内蠕变试验,针对不同荷载和温度组合,对土工格栅的蠕变特性进行了对比试验。通过对试验结果的综合比较,详细地分析了土工格栅载荷-应变等时曲线、蠕变曲线及松驰曲线的变化特征,由此并基于粘弹性理论提出了能够反映土工格栅蠕变特性的粘弹性本构模型,提出了模型参数的合理确定方法。并通过模型预测与试验结果的对比论证了所建议粘弹性本构模型的可靠性  相似文献   

盾构近距离穿越施工的工作面土压力研究   总被引：10，自引：0，他引：10  

廖少明  杨俊龙  奚程磊  彭芳乐  侯学渊 《岩土力学》2005,26(11):1727-1730

盾构近距离穿越已建地下构筑物位移场的影响因素及其敏感性与常规施工有较大的不同。结合上海地铁四号线隧道超近距离穿越运营地铁隧道的工程实例发现当盾构接近上方近距离（净距为1.05 m）地铁隧道时地层土压力发生较大变化,相应的盾构土舱管理压力需作相应调整。根据隧道受荷机理及弹性力学原理,找到了这一问题的理论依据,便推导了相关理论公式,并在实际工程中设计了盾构土仓管理压力分步台阶控制方案,对盾构控制起到了很好的指导作用,成功地将地铁位移控制在5 mm之内。土压力实测结果与理论推算的数值大小及分布相当接近,说明所采用的理论方法是正确可靠的,在盾构超近距离穿越施工中具有重要指导意义。  相似文献   

西北荒漠区6种珍稀濒危植物的种子微形态特征   总被引：10，自引：3，他引：7  

马骥  李新荣  李俊祯  张景光 《中国沙漠》2005,25(2):275-280

首次报道了我国沙区6种珍稀濒危植物的种子微形态结构的光镜及扫描电镜观察结果。实验结果表明:沙冬青、四合木、半日花等6种珍稀濒危植物的种子微形态特征呈现出丰富的多样性,且大多具有复杂精细的表面纹饰。  相似文献   

基于地质建造的西南山区生态地质编图探索与实践——以邛海—泸山地区为例     

刘洪  李文昌  欧阳渊  张景华  张腾蛟  李佑国  黄瀚霄  黄勇  李富  陈敏华  李樋  吴君毅 《地质学报》2023,97(2):623-638

地质作用是形成区域生态环境格局的重要驱动力之一,岩石圈表层地质建造是土壤圈、水圈、大气圈和生物圈的载体,制约着地形地貌、水文地质、土壤物理化学性质以及地质灾害等生态地质条件,进而对整体的生态平衡起着重要的作用。生态地质研究在于探索生态环境与地质条件之间的联系,从地质学的视角,探寻生态系统运行与演化机制。本文在四川邛海—泸山地区生态地质调查实践中,探索了一套适用于西南山区的土壤地质图、生态地质剖面和生态地质图等生态地质系列图件的编制方法。研究认为,生态地质系列图件应是岩石圈- 土壤圈- 生物圈等多圈层融合的地球表层系统在地质图上的反映,其表达内容主要包括：作为生态环境物质基础的地表基质层（岩石圈和土壤圈）的生态功能属性、地表覆盖的生态系统和人类活动的现状和展布、生态地质单元的生态功能属性等。基于地质建造和地表基质层的生态地质系列图件,能系统地反映研究区地球表层系统中各生态地质要素的现状、特征、展布和交互关系,为生态保护修复及国土空间用途管制提供地球科学依据。  相似文献   

滇西北宾川地区主要活动断裂及其活动构造体系   总被引：1，自引：0，他引：1  

罗睿洁  吴中海  黄小龙  黄小巾  周春景  田婷婷 《地质通报》2015,34(1):155-170

通过卫星遥感解译和地表调查,对滇西北宾川地区活动断层进行了相对全面的调查研究,并对该区活动构造体系提出了新认识。研究表明,该区发育以北东向正断层和走滑断层为主的活动断裂,并构成了典型的张扭性帚状构造,控制了宾川地区构造地貌的发育。该活动构造体系的主干活动断裂是近南北向程海—宾川断裂向南至宾川处分解后形成的2条分支断层,即近南北向以正断性质为主兼具左旋的宾川断裂(F1)和北东向左旋走滑的上沧—鱼棚断裂(F2)。宾川地区活动构造体系是在区域近东西向伸展和微地块顺时旋转的共同作用下形成的,反映了滇西北裂陷带在青藏高原整体瞬时旋转背景下的左旋拉分运动模式。同时,对宾川地区活动构造体系的研究也有助于更好地认识该区未来的强震危险性,对于其中主干断裂(F1、F2)的大震危险性应给予更多关注。  相似文献   

豫西黄沟金矿床地质地球化学特征     

王秀全 《矿产与地质》2015,(3)

通过研究黄沟金矿床中岩石地球化学特征,从而探讨太华群地层对于该区金矿床成矿的作用。研究表明(1)本区的片麻岩原岩主要为火成岩,属高钾钙碱性系列,且金矿石一般都明显贫钠而富钾、富钙,SiO2含量普遍较高,Au品位随SiO2的含量增高而呈正相关变化;(2)微量元素特征表明矿石样品以Rb、Ta、Ti等元素强烈亏损,Ba、Sm和Y元素强烈亏损为特征,与太华群片麻岩和熊耳群安山岩的标准化分布曲线型式接近,说明金矿化可能与太华群片麻岩和(或)熊耳群安山岩具有成因上的联系;(3)稀土元素特征表明多数金矿石的轻稀土略亏损、重稀土略富集,弱负铕异常与矿区出露的各类岩石的稀土元素标准化分布曲线(右倾型)不同,而具深源特性;个别金矿石的标准化曲线形态一定程度上具片麻岩或(和)安山岩的特征,呈弱负铕异常的右倾形态,暗示了太华群片麻岩和(或)熊耳群安山岩也贡献了部分成矿物质。  相似文献   

Trace and rare earth element geochemistry of the Upper Triassic mudstones in the southern Ordos Basin,Central China     

Xin‐Wei Qiu  Chi‐Yang Liu  Fei‐Fei Wang  Yu Deng  Guang‐Zhou Mao 《Geological Journal》2015,50(4):399-413

Oil‐source correlation studies have demonstrated that the crude oils in the Ordos Basin were mainly derived from organic‐rich lacustrine mudstones of the Yanchang Formation. The sedimentology, petrology and organic geochemistry of these mudstones have been studied intensively, but their trace and rare earth element (REE) characteristics have received little attention. In this paper, we present trace and rare earth element data of the Upper Triassic Yanchang Formation mudstones in the southern Ordos Basin to constrain the palaeoenvironment, provenance and depositional setting. Our results show that the REE and trace element concentrations of the Yanchang Formation mudstones are higher than those of the upper continental crust (UCC). The Sr contents and Sr/Ba and Y/Ho ratios of these mudstones indicate the absence of a marine transgression during the sedimentation of the Upper Triassic mudstones. The depositional environment of the Upper Triassic mudstones was slightly oxic as evidenced by the values of Eu/Eu*, Ce/Ce*, Ce_anom, δU, U/Th, V/Cr and Ni/Co. The UCC‐normalized distribution pattern of REEs, spider diagrams, the ratios of related elements, the bivariate diagrams of Th/Sc–Zr/Sc and La/Th–Hf and the ternary plots of La–Th–Sc and Th–Sc–Zr/10 signify that the provenances of the Chang9–7 mudstones were mainly derived from a continental island arc, whereas the provenances of the Chang6–3 mudstones were mainly derived from a mixture of continental island arc and active continental margin, and the latter contain less recycled materials. Combined with the previous studies of detrital zircon dating and petrography of the Yanchang Formation sandstones in the southern Ordos basin, we propose that the Qinling orogenic belt served as one of the primary source regions occurring between the Chang7 and Chang6 periods, corresponding to the initial uplift of the west Qinling Mountains due to the collision between the Yangtze and North China blocks. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

冕宁县牦牛坪稀土矿区“7·18”水石流灾害     

杨敏  马东涛  陈英 《山地学报》2014,32(6)

2013-07-17T20:00—2013-07-18T3:00,冕宁县牦牛坪稀土矿区7 h降雨219 mm,瓦维埃河及支沟发生6处水石流,对采矿场、选矿厂、地面站、弃土场、排洪沟、矿山公路及矿山环境造成严重危害。研究发现:牦牛坪矿区具备水石流发育的充分条件,泥石流沟处于发育壮年期,但泥石流处于衰退期。"7·18"水石流是在100 a一遇强暴雨激发下,沟床及岸坡老泥石流堆积物和沟床堆积物在山洪冲蚀下切、侧蚀下形成的,暴雨和水石流暴发频率同步。其水石流具有固体物质粗大(最大粒径8 m),块砾石含量高(80%以上),粉、粘粒含量极低(小于1%),容重高(1.6~1.85 t/m3),冲淤变化大(最大冲深10 m,最大淤积5 m),规模大(总冲出量50×104m3)等特点。  相似文献   

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戴苗  刘坚  蒋玲霞  赵凌云  张念 《大地测量与地球动力学》2014,34(3):48-51

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Rare earth elements in cold seep carbonates from the southwestern Dongsha area,northern South China Sea     

《Marine and Petroleum Geology》2014

The circulation of methane-rich fluids at cold seeps often leads to the precipitation of seep carbonates close to the seafloor along continental margins, which can be used as records of past fluid seepage. Rare earth element (REE) concentrations in seep carbonates have been used to trace fluid sources and provide information on associated biogeochemical processes at cold seeps. The REE concentrations of a series of carbonates collected from cold seeps in the southwestern Dongsha area of the northern South China Sea are analyzed in this study. The total REE contents (ΣREE) of the seep carbonates analyzed show a wide variation from 17 ppm to 523 ppm with an average ΣREE value of 54 ppm, which are higher than the typical marine carbonate values of ∼28 ppm commonly reported and also higher than those of the carbonates from other cold seep areas. A positive correlation between Fe–Mn content and ΣREE was observed. These results suggest that the seep carbonates of this study were primarily controlled by the methane-derived fluid from which they precipitated. The Fe-rich dolomite and siderite, which are the main components of the carbonates, are responsible for the enrichment of the REE. A slight positive Ce anomaly observed in the shale-normalized REE patterns of the studied seep carbonates suggests that they formed in anoxic conditions, and the correlations between Ce/Ce* and La_N/Sm_N, Ce/Ce* and Dy_N/Sm_N, Ce/Ce* and ΣREE further reveal that the REE characteristics of most seep carbonate samples preserve the original redox conditions in which they precipitated and late diagenesis has had little effect on the REE. However, the REE characteristics of sub-samples DS2-2B, DS1-6A and DS1-7A are very different from those of the other sub-samples, indicating a greater impact of late diagenesis and post-oxidation favored REE enrichment.  相似文献