冻土单轴抗压强度影响因素的试验研究   总被引：3，自引：3，他引：0  

蔡正银  吴志强  黄英豪  侯伟 《冰川冻土》2015,37(4):1002-1008

新疆地区是我国典型的咸寒区, 渠基土在冬季的冻结引起了输水渠道衬砌的破坏. 为了解冻结状态下渠基土的物理力学特性, 在常应变率条件下对新疆北疆季节性冻土区的含硫酸钠渠基土进行了多种条件下的单轴抗压强度试验. 结果表明: 单轴抗压强度随温度的降低线性增加; 单轴抗压强度随干密度的增加而增大, 二者之间具有较好的幂函数关系. 与氯化钠盐渍土不同, 硫酸盐渍土的单轴抗压强度随着硫酸钠含量的升高而增大, 并且呈现近似线性增加的特性.  相似文献   

气泡混合轻质土干湿循环和硫酸钠耐久性试验研究     

刘楷  李仁民  杜延军  魏明俐 《岩土力学》2015,36(Z1):362-366

采用水泥和地聚合物作为固化剂制备气泡混合轻质土,测试水泥轻质土（LCSC）和地聚合物轻质土（LGSC）在干湿循环和硫酸钠长期浸泡环境下的无侧限抗压强度和质量变化率,并相互进行对比,分析干湿循环级数和硫酸钠浸泡环境对其强度特性的影响规律。结果表明,标准养护地聚合物轻质土强度约为水泥轻质土的2倍;干湿循环后地聚合物轻质土强度随干湿循环级数衰减较快且破坏程度逐渐增大,水泥轻质土强度未出现明显衰减,与水泥轻质土相比,地聚合物轻质土抗干湿能力较差;硫酸钠溶液浸泡120 d后,地聚合物轻质土强度出现小幅下降,约为标准养护28 d试样的80%;水泥轻质土出现开裂破坏,与水泥轻质土相比,地聚合物轻质土抗硫酸钠侵蚀能力较强。  相似文献   

硫酸盐渍土击实性能及影响因素试验研究     

文桃  米海珍  杨鹏  应赛  王月礼 《岩土力学》2015,36(7):1945-1952

为了全面地揭示硫酸盐渍土击实性能的变化原因和规律,对不同条件下配制的硫酸盐渍土进行了一系列的轻型击实试验。试验研究表明,含盐量对硫酸盐渍土最大干密度和最优含水率的影响规律并不是单一不变的,它取决于土中硫酸钠的3种状态（硫酸钠溶液、无水硫酸钠和十水硫酸钠）及3种状态间的相对含量。硫酸盐渍土的最大干密度和最优含水率与土中不同状态硫酸钠相对含量间的关系曲线具有反相关性。闷料时间和初始含水率对硫酸盐渍土击实性能的影响与含盐量有关,当含盐量较低（如1.5%）时,其影响甚小;当含盐量较高（如5.0%）时,其影响显著。硫酸盐渍土在由湿到干的过程中会出现“假干现象”。该试验结果对工程中硫酸盐渍土的击实性能和压实度的合理评价都具有重要的参考价值。  相似文献   

硫酸钾镁肥浮选尾矿热浸-冷结晶法提取七水硫酸镁工艺研究   总被引：3，自引：3，他引：0       下载免费PDF全文

李海民  雷光远  陈育刚  何勇峰 《盐湖研究》2012,20(2):44-51

以国投新疆罗布泊钾盐有限责任公司(简称国投罗钾)提供的硫酸钾镁肥浮选尾矿和氯化镁饱和卤水为原料,探索出了一条以硫酸钾镁肥浮选尾矿为原料,以氯化镁饱和溶液为浸取介质,通过中温溶浸、冷却结晶(包括盐田冷析)等工艺方法制取七水硫酸镁的工艺路线,给出了各工序的工艺技术条件及主要技术指标。  相似文献   

The thermal expansion and crystal structure of mirabilite (Na<Subscript>2</Subscript>SO<Subscript>4</Subscript>·10D<Subscript>2</Subscript>O) from 4.2 to 300 K,determined by time-of-flight neutron powder diffraction     

H. E. A. Brand  A. D. Fortes  I. G. Wood  K. S. Knight  L. Vočadlo 《Physics and Chemistry of Minerals》2009,36(1):29-46

We have collected high resolution neutron powder diffraction patterns from Na₂SO₄·10D₂O over the temperature range 4.2–300 K following rapid quenching in liquid nitrogen, and over a series of slow warming and cooling cycles. The crystal is monoclinic, space-group P2₁/c (Z = 4) with a = 11.44214(4) Å, b = 10.34276(4) Å, c = 12.75486(6) Å, β = 107.847(1)°, and V = 1436.794(8) Å³ at 4.2 K (slowly cooled), and a = 11.51472(6) Å, b = 10.36495(6) Å, c = 12.84651(7) Å, β = 107.7543(1)°, V = 1460.20(1) Å³ at 300 K. Structures were refined to R _P (Rietveld powder residual, \( R_{P} = {{\sum {\left| {I_{\text{obs}} - I_{\text{calc}} } \right|} } \mathord{\left/ {\vphantom {{\sum {\left| {I_{\text{obs}} - I_{\text{calc}} } \right|} } {\sum {I_{\text{obs}} } }}} \right. \kern-\nulldelimiterspace} {\sum {I_{\text{obs}} } }} \)) better than 2.5% at 4.2 K (quenched and slow cooled), 150 and 300 K. The sulfate disorder observed previously by Levy and Lisensky (Acta Cryst B34:3502–3510, 1978) was not present in our specimen, but we did observe changes with temperature in deuteron occupancies of the orientationally disordered water molecules coordinated to Na. The temperature dependence of the unit-cell volume from 4.2 to 300 K is well represented by a simple polynomial of the form V = ? 4.143(1) × 10^?7 T ³ + 0.00047(2) T² ? 0.027(2) T + 1437.0(1) Å³ (R ² = 99.98%). The coefficient of volume thermal expansion, α _V , is positive above 40 K, and displays a similar magnitude and temperature dependence to α _V in deuterated epsomite and meridianiite. The relationship between the magnitude and orientation of the principal axes of the thermal expansion tensor and the main structural elements are discussed; freezing in of deuteron disorder in the quenched specimen affects the thermal expansion, manifested most obviously as a change in the behaviour of the unit-cell parameter β.  相似文献   

Coincident negative shifts in sulfur and carbon isotope compositions prior to the end-Permian mass extinction at Shangsi Section of Guangyuan, South China     

Pengwei Li  Junhua Huang  Min Chen  Xiao Bai 《Frontiers of Earth Science》2009,3(1):51-56

Sulfur isotope composition of carbonate-associated sulfate (δ³⁴S_CAS) and carbon isotope composition of carbonate (δ¹³C_carb) were jointly investigated on the Late Permian rocks at Shangsi Section, Guanyuan, Northeast Sichuan, South China. Both δ³⁴S_CAS and δ¹³C_carb show gradual decline trends in Late Permian strata, inferring the occurrence of the long-term variation of marine environmental conditions. Associated with the long-term variation are the two coincident negative shifts in δ³⁴S_CAS and δ¹³C_carb, with one occurring at the boundary between Middle Permian Maokou Formation and Late Permian Wujiaping Formation and another at Middle Dalong Formation. Of significance is the second shift which clearly predates the regression and the biotic crisis at the end of Permian at Shangsi Section, providing evidence that a catastrophic event occurred prior to the biotic crisis. The frequent volcanisms indicated by the volcanic rocks or fragments, and the upwelling are proposed to cause the second negative excursion. An abrupt extreme negative δ³⁴S_CAS (ca. −20‰) associated with a low relative concentration of CAS and total organic carbon without large change in δ¹³C_carb is found at the end of the second shift, which might arise from the short-term oxygenation of bottom waters and sediments that resulted from the abrupt sea level drop.  相似文献   

Fe~(2+)活化过硫酸盐在石油污染土壤中修复实验研究   总被引：1，自引：0，他引：1  

张译之  贾汉忠  汪立今 《岩石矿物学杂志》2017,36(6):881-886

硫酸根自由基的高级氧化技术以高效率、污染少等优点被广泛用于环境污染治理。本文以实际石油污染土壤为对象,运用该体系对土壤进行修复研究,分别从Na_2S_2O_8/Fe~(2+)摩尔比、体系pH值、Na_2S_2O_8/Fe~(2+)投加量等方面开展了实验研究。实验表明:当Na_2S_2O_8/Fe2+摩尔比为2∶3时,石油污染物的降解效果最好,体系的pH值对降解效果影响不大,1 g土壤中浓度为0.1 mol/L的过硫酸钠和硫酸亚铁溶液的最佳加入量为2 m L、3 m L时,对土壤的降解效果最为明显,故每吨污染土壤的添加量大约为2×10~6m L、3×10~6m L。  相似文献   

热化学硫酸盐还原作用(TSR)与贵州汞(金锑)矿床成因机制再探讨——从黔东锰矿古天然气渗漏沉积成矿理论得到的启示     

陈履安  周琦 《地质论评》2019,65(2):431-437

受黔东地区南华纪锰矿的古天然气渗漏成矿理论启示,在研究贵州典型汞矿成矿作用的地球化学机理的基础上,本文将热化学硫酸盐还原反应(TSR)引入成矿过程。提出富含汞(包括气态汞)、还原硫、Cl^-的含矿—运矿流体与含汞围岩相互作用,进一步论证推断深部油气藏的圈闭体系和围岩都可能是汞的重要来源。在较高温度条件下,有油气(烃类)参与的硫酸盐热化学还原作用是还原硫(H_2S、HS^-、S^2-)的主要来源,而油气(烃类)在成矿作用中发挥了还原剂的重要作用。含矿的热流体(藏)渗漏或者喷溢,同时又溶解流经围岩中以辰砂、单质汞等形式存在的汞,转变为可溶解的汞—硫配合物而运移,在系统从封闭转为开放的构造作用下,气体组分逸失,在还原硫浓度m(S^2-)降低、Eh升高、pH降低、压力和温度降低以及盐度降低等物理化学条件下成矿。类比研究显示,贵州一些金、锑等金属矿床具有与此类汞矿床类似的成矿机理。故20世纪80年代以来的这类(汞、金、锑)金属矿床的沉积—改造成因及作者提出的相关地球化学机理应当加以适当修正。  相似文献   

细粒硫酸钠盐渍土盐冻胀特性试验研究   总被引：1，自引：1，他引：0  

于天佑  吴亚平  司培国  张磊  孔令楠  蒲增钢 《冰川冻土》2019,41(2):407-210

为探究温度与硫酸钠含量对细粒硫酸钠盐渍土盐冻胀率及盐胀占比的影响,取兰州黄土作为素土人工配盐,用平衡公式进行理论推导,并设计了室内试验对其进行验证。结果表明：当压实度为92%、含水率为最优含水率16.8%时,随着含盐量的升高,细粒硫酸钠盐渍土的冻结温度随硫酸钠含量的增大而降低,且随着温度的降低,盐胀率的变化趋势与盐冻胀率基本一致。在冻结温度以下至-5 ℃盐胀发展速度最快,在-5 ℃以下盐胀率增长很小;在压实度为92%、含水率为最优含水率16.8%条件下,在硫酸钠含量不变时,温度越低,盐胀占比越大;温度不变时,硫酸钠含量越高,盐胀占比越大,在冻结温度以上盐胀占比为100%,但当温度降至-3~-4 ℃时盐胀占比降到50%,在-10 ℃以下盐胀占比基本保持不变。  相似文献   

Microbial Geochemical Characteristics of the Coalbed Methane in the Shizhuangnan Block of Qinshui Basin,North China and their Geological Implications     

LI Yang  SHI Wei  TANG Shuheng 《《地质学报》英文版》2019,93(3):660-674

Methanogens and sulfate reducing bacteria were detected by the 16SrRNA sequencing of coalbed methane(CBM)co-produced water in the south of the Qinshui Basin,which is indicative of the presence of secondary biological gas in the south of this basin,in contradiction to the previous understanding of thermogenic gas.This work systematically collected water samples from the CBM wells in the Shizhuangnan Block and analyzed the microbial geochemical characteristics from the aspects of water ions,hydrogen and oxygen isotopes,dissolved inorganic carbon and microbial diversity.It is shown that the Shizhuangnan Block has a nearly SN-trending monoclinic structure,and the elevation of coal seam decreases gradually from the east to west.Because of the water blocking effect of Sitou fault in the west,the precipitation flowed from the east to west,and gradually transited to stagnant flow area.The concentration variation of some ions such as Na~+,K~+,Ca~(2+),Mg~(2+),Cl~-,HCO~-_3 and total dissolved solids(TDS)suggest the variation of redox condition in the coal reservoir water.The 16SrDNA sequencing analysis of the collected water samples detected the presence of methanogens and sulfate reduction bacteria.The presence of methane production zone and sulfate methane transition zone(SMTZ)was identified.The effect of methanogens in the methane production zone leads to an increase in the methane concentration,resulting in a high gas content in the study area.In the SMTZ,most methane is consumed by anaerobic oxidation due to high sulfate concentrations.  相似文献