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以往整治滑坡,较多地使用大口径挖孔桩或钻孔灌注抗滑桩,周期长、成本高。川地208队在治理重庆制药五厂已处于危急态势的滑坡中,采用“天平式”控制、勘治结合、快速抢险,用三排小径密抗桩(300mm口径)整治,取得明显成效。实践表明:浅层滑坡采用较小口径的密抗桩,并辅以排水,能达到事半功倍的效果。 相似文献
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奥塔北井田煤层多、埋藏浅,煤层结构及煤层厚度变化大,存在煤层对比困难、煤层露头难以控制等问题。为此将先期开采区块划分为二维区与三维区,其中二维区采用小道距、小炮距的观测系统,重点控制浅部地层倾角和煤层露头;三维区采用8线8炮、小CDP网格的观测系统,重点解决煤层结构问题。在后期的处理解释中,采用分频处理方法,以提高地震资料中的高频能量;利用波阻抗反演,进行煤层反射波标定,以提高煤层分叉合并与煤层夹矸的分辨能力。奥塔北井田先期开采区块勘探实例表明,二维与三维地震互补的勘探方法,对控制煤层露头、解释煤层分叉合并、确定煤层结构与煤层间关系等地质现象,具有较好的勘探效果。 相似文献
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小兴安岭平顶山大地构造位于兴蒙造山带东段,隶属松嫩地块。本文对小兴安岭平顶山一带碱长花岗岩和正长花岗岩进行了锆石U-Pb年代学和岩石地球化学研究,以确定其形成时代、岩石成因及大地构造背景。结果显示：碱长花岗岩形成于（189±3） Ma,正长花岗岩形成于（191±3） Ma,同为早侏罗世岩浆事件演化的产物;岩石具有高硅（w（SiO2）为75.00%~77.60%）、富碱（w（K2O+Na2O）为7.13%~9.00%）、贫镁（w（MgO）为0.05%~0.45%）、贫钙（w（CaO）为0.17%~1.10%）、低磷钛（w（P2O5）为0.01%~0.07%,w（TiO2）为0.09%~0.23%）的特点,A/CNK值为0.94~1.17,属于准铝质-弱过铝质、高钾钙碱性系列岩石;亏损高场强元素Nb、P、Ti、Ta和大离子亲石元素Ba、Sr,Rb、K、Th、Hf等元素具有明显的正异常;稀土元素总量（w（ΣREE））为（38.76~297.13）×10-6,稀土配分曲线显示为轻稀土略微富集、重稀土较为平坦缓向倾斜的右倾型,具明显的负Eu异常。锆石饱和温度值及地球化学特征等多种证据显示,岩石为高分异的I型花岗岩。结合小兴安岭区域构造演化特征分析,研究区早侏罗世花岗岩类为松嫩地块与佳木斯地块沿嘉荫—牡丹江缝合带碰撞拼合后伸展环境下的产物,岩浆起源于下地壳火成岩物质的部分熔融。 相似文献
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嫦娥二号卫星于2011-06～2012-04实施拓展试验,运行在绕日地系L2点的Lissajous轨道上。拓展试验期间嫦娥二号卫星距离地球最远约1 700 000km,随着卫星与地球距离的增加,测轨数据的噪声水平也明显增加;另一方面,距离的增加使得飞行过程中动力学约束逐渐减弱,测轨几何可确定性变差,定轨计算的难度也相应提升。这两个因素对测控系统提出了更为严格的要求。描述了嫦娥二号卫星拓展试验期间的轨道计算情况并进行评估。分析表明,在当前的测控条件下,逃逸初期轨道计算的精度优于km级,速度精度优于1cm/s,而随着飞行距离的增加,轨道计算所需的测轨弧段也相应增加,在转移阶段后期,连续使用20d以上的测轨数据进行定轨计算,通过弧段搭接与轨道预报比较,内符合满足2km的精度水平。 相似文献
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SONG Lihao CAO Yuting XIE Tianhe CHEN Yuyao GAO Yuan WANG Songjie LI Xuping 《《地质学报》英文版》2023,97(6):1640-1656
Gneisses with anatectic characteristics from the Liansan island in the Sulu UHPM (ultra-high pressure metamorphic) belt were studied for petrography, titanite U-Pb dating and mineral geochemistry. Three origins of garnets are distinguished: metamorphic garnet, peritectic garnet and anatectic garnet, which are formed in the stages of peak metamorphism, retrograde anatexis and melt crystallization, respectively. The euhedral titanite has a high content of REE and high Th/U ratios, which is interpreted as indicating that it was newly-formed from an anatectic melt. The LA-ICP-MS titanite U-Pb dating yields 214–217 Ma ages for the titanite (melt) crystallization. The distribution of trace elements varies in response to the different host minerals at different stages. At the peak metamorphic stage, Y and HREE are mainly hosted by garnet, Ba and Rb by phengite, Sr, Nb, Ta, Pb, Th, U and LREE by allanite and Y, U and HREE by zircon. During partial melting, Y, Pb, Th, U and REE are released into the melt, which causes a dramatic decline of these element contents in the retrograde minerals. Finally, titanite absorbs most of the Nb, U, LREE and HREE from the melt. Therefore, the different stages of metamorphism have different mineral assemblages, which host different trace elements. 相似文献
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地震勘探以其高精度、低成本、高效率在煤田勘探中已广泛应用,梁宝寺煤田采用三维地震勘探技术,在解释构造、煤层、岩浆岩等方面取得了显著的效果,为煤炭勘查作出了重要贡献。 相似文献
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Effects of rainfall amount and frequency on vegetation growth in a Tibetan alpine meadow 总被引：1，自引：0，他引：1
Baocheng Zhang Junji Cao Yanfen Bai Xuhui Zhou Zhigang Ning Songjie Yang Lin Hu 《Climatic change》2013,118(2):197-212
Over the past decades, rainfall amount and frequency changed considerably on the Tibetan Plateau. However, how altered rainfall pattern affects vegetation growth and phenology in Tibetan alpine grasslands is poorly understood. In this study, we investigated the long-term effects of rainfall amount and frequency on production (i.e., aboveground biomass, AGB) and phenology of three perennial plants in a Tibetan alpine meadow from 1994 to 2005. Growth period (i.e., the dates from greening to senescence) was referred to plant phenology here. Our results showed that annual precipitation and total rainfall from large events (≥ 5 mm per day) were mainly distributed in the growing season, which increased significantly from 1994 to 2005 with more increment in May and July (p?<?0.05). Total AGB and growth periods of three plants were linearly correlated with annual precipitation and total rainfall from large events, but have insignificant correlations with total rainfall from small events (< 5 mm per day) and rainfall frequency (including small, large, and all events). The results suggest that aboveground plant production and phenology are more sensitive to changes in large rainfall events (≥ 5 mm per day) than small events (< 5 mm per day) in the alpine meadow ecosystems. 相似文献
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Mineralogy and Petrology - This study presents data of in-situ mineral major and trace element chemistry, whole-rock major and trace element and Sr–Nd isotope geochemistry, as well as zircon... 相似文献