络合剂淋洗Cu污染粉土的土柱试验研究

以当前我国备受关注的土体污染为背景,通过土柱试验研究了不同络合剂对Cu的淋洗效果,结果表明:乙二胺四乙酸二钠二水合物（ethylenediaminetetraacetic acid disodium saltdihydrate,EDTA）淋洗效果最佳,柠檬酸（citric acid,CIT）次之,氨三乙酸三钠盐单水合物（nitrilotriacetic acid trisodium salt monohydrate, NTA）淋洗效果相对最差;使用不同浓度的EDTA淋洗负载量为150 mg/kg的Cu污染土,浓度增大并未有效促进Cu的解吸,而较小浓度（0.005 mol/L）的EDTA是有效且经济的浓度,其对Cu的去除率达84%;0.015 mol/L的EDTA淋洗不同负载量的Cu污染土,随负载量增加,淋洗率下降,最高去除率为84%,但去除量增加;研究结果可为重金属污染土的淋洗修复工艺提供理论参考依据。     

利用GPR天线-目标极化的瞬时属性分析方法探测LNAPL污染土壤

轻非水相流体(LNAPL)泄漏后会对土壤和地下水造成严重污染,为了准确探测出LNAPL泄漏范围,本文将GPR天线-目标极化的瞬时属性分析方法应用于轻非水相流体污染土壤探测的研究中。采用注入柴油的石英砂砂箱在实验室建立污染土壤模型,利用探地雷达对该污染土壤分别进行天线方位为0°、90°的测量。LNAPL土壤污染物形状、大小、结构并不规则,因此可以通过0°和90°方位天线测量来分析天线-目标极化特征,了解目标物的走向、形状等地下介质信息。通过对预处理后的包含天线-目标极化特征的信息进行瞬时属性分析,LNAPL污染范围可以被清晰地识别,提高了GPR探测能力。     

Study on the deformation and failure modes of filling slope in loess filling engineering: a case study at a loess mountain airport

Lvliang airport is a typical loess filling engineering located in 20.5 km north of Lvliang City in Shanxi Province, China. By the end of March 2012, 14 fissures extending more than 7.5 m were observed in a loess-filled slope, of which the longest fissure is up to 82 m. Field monitoring and laboratory tests have been performed to investigate the slope failure modes. The test program includes wetting tests on unsaturated compacted samples and stress path tests on saturated samples. Field monitoring and observations show that differential settlement caused by non-homogeneity in compacted loess density might lead to the formation of fissures in the loess-filled slope. It was founded that the wetting deformation contributed to the development of differential settlement. Fissures are the essential factor for the loess-filled slope failure. Four deformation stages exhibit in the loess-filled slope prior final failure including development of the fissures, softening of the compacted loess, creeping of the slope leading edge and fissuring of the trailing edge and formation of the through-sliding surface. Development of the sliding surface mainly includes upward and downward expansion of the fissures. Upward expansion is a wetting failure process in loading condition, while downward expansion is a load-off wetting process. In addition, development of the sliding surface is accelerated by softening of the compacted soils as a result of water infiltration. Therefore, the key for taking countermeasures against filling landslides is to monitor and control the development of differential settlement and fissures in the slope shoulders. Digging out and extra-filling the fissures are an effective way for preventing these landslides.     

An insight into the surface velocity of Inylchek Glacier and its effect on Lake Merzbacher during 2006–2016 with Landsat time-series imagery

Mountain glacier is one of the extremely sensitive indicators for climate change, and its surface motion distribution and corresponding variation are valuable information for understanding ice mass exchange and glacier dynamics. This paper presents the long-term ice velocity distributions of Inylchek Glacier in the Tianshan region by pixel-tracking algorithm with time-series Landsat imagery acquired during 2006–2016. Then the monitored ice motion fields of Inylchek Glacier were carefully analyzed and revealed a generally similar spatial distribution characteristic. Most of the ice of the North Inylchek Glacier remains in a stagnant state except for the upstream part, but a relatively high velocity of 20–40 cm/day with an RMSE of 3 cm/day was observed on most part of the South Inylchek Glacier, except for the slow-moving glacier terminus. We also state the glacier dynamics around Lake Merzbacher and their possible effect on its glacier lake outburst flood (GLOF) risk. Besides, the surface velocity distribution on South Inylchek Glacier surface during the ablation period from 2014 to 2016 was also established and also compared with annual velocity. The corresponding difference yields that there is a positive relation between ice motion and temperature variation. Therefore, the time-series ice surface motion yielded by the Landsat imagery thus could provide us an efficient and low-cost way to analyze the current state and changes in glaciers, thanks to the continuous and regular spaceborne observations provided by the Landsat satellites.     

Development and verification of the comprehensive model for physical properties of hydrate sediment

Natural gas hydrate is widely distributed all over the world and may be a potential resource in the near future, whereas hydrate dissociation during the development affects wellbore stability and drilling safety. However, the present modeling of hydrate reservoir parameters ignored the influence of effective stress and only considered the hydrate saturation. In this paper, a series of stress sensitivity experiments for the unconsolidated sandstone were carried out, and the influence of mean effective stress on physical parameters was obtained; a comprehensive model for the physical parameters of hydrate reservoir was developed subsequently. With the help of ABAQUS finite element software, the established comprehensive model was verified by the use of the wellbore stability numerical model of hydrate reservoir. The verification results show that ignoring the effect of mean effective stress on the parameters of hydrate formation aggravates the invasion of drilling fluid into the hydrate formation. Besides, ignoring the stress sensitivity of reservoir physical parameters will underestimate the wellbore instability during hydrate drilling, which will be a threat to the safety of gas hydrate drilling. At the end of the drilling operation, the maximum plastic strain of the model for considering and not considering stress sensitivity was 0.0145 and 0.0138, respectively. Therefore, the established comprehensive model will provide a theoretical support for accurately predicting the engineering geological disasters in hydrate development process.     

Mechanical behavior and micro-structure of cement kiln dust-stabilized expensive soil

In this study, the effects of cement kiln dust (CKD) on the swelling properties, strength properties, and microstructures of CKD-stabilized expansive soil were investigated. Samples were prepared and stabilized with different CKD content ratios, ranging from 0 to 18% by dry mass. The results obtained show that the maximum swelling pressures decrease exponentially with increases in CKD content. Both the cohesion and unconfined compressive strength (UCS) increase at ratios below 10% CKD and then decrease slightly, above that ratio. CKD can also improve the strength of saturated, expansive soil. There is no visible change of UCS for soil without CKD when cured, while the UCS of a sample with 10% CKD content after curing for 90 days is higher than that after curing for only 1 day. This indicates that CKD can improve the long-term strength of expansive soil. Finally, microstructure analysis reveals that the addition of CKD reduces the montmorillonite content of expansive soil and decreases its swelling properties. The addition of CKD also changes the pore volume distribution, both the size and amount of macro-pores and micro-pores decrease with increase in CKD content. For saturated samples, the size of macro-pores is obviously reduced, while that of micro-pores is slightly increased for both treated and untreated soils. Hydration and saturation processes make the soil structure become dispersive which results in a lower strength, and adding CKD can restrain this process. The suggested optimal CKD content is between 10 and 14% and with a curing time of more than 27 days.     

Application of instantaneous amplitude gradient for ground penetrating radar signal analyses

Ground penetrating radar (GPR) is an effective geophysical method for environmental and engineering exploration. However, significant background interference occurs around most work sites, which increases the difficulty of analyzing and interpreting GPR profiles. For time-distance profile analyses, more accurate results can be obtained using the instantaneous parameters of the analytic signals. In this study, these instantaneous parameters are extracted and compared using 1D model waveform and 2D model strong interference profiles. The results show that the instantaneous amplitude gradient effectively reflects the model information, even under strong interference. The instantaneous amplitude gradient is applied to GPR survey data from a study site, and the results indicate that the technique reflects the underground structure information of the survey area. Drilling verification further confirms that the instantaneous amplitude gradient accurately reflects the underground structure information.     

吉林永吉县头道沟地区镁铁—超镁铁质岩U-Pb年代学研究及地质意义

吉林省永吉县头道沟地区出露许多与头道沟岩组相伴产出的镁铁—超镁铁质岩,鉴于其处于长春-延吉构造带附近而受到业内关注,但由于缺少高精度年代学资料,制约了对区域大地构造的深入研究。本文采用锆石U-Pb(LA-ICP-MS)方法,对镁铁—超镁铁质岩进行了年代学研究。变质辉绿岩年龄为270±5 Ma,变质橄榄岩中捕获锆石最小年龄为297 Ma,考虑岩石组合及二者紧密相伴产出,认为二者均形成于中二叠世。镁铁—超镁铁质岩中捕获的锆石记录了华北克拉通及其北缘多次重要的构造热事件。其中,变辉绿岩中获得446±6 Ma的年龄与变质橄榄岩中获得的不一致线下交点434±240 Ma年龄共同对应了华北克拉通北缘早古生代的重要构造岩浆热事件;大量的1.8~2.4Ga年龄对应古元古代辽吉造山带热事件;1377 Ma、1542 Ma与蓟县系建造时代对应;869~997 Ma与青白口系建造时代对应;在变质辉绿岩中还存在众多3.0~3.2Ga锆石年龄。分析上述年龄结构及龙岗陆块北缘古生代地质体分布特征,推测研究区深部可能存在古老的变质基底,同时也表明研究区出露的镁铁—超镁铁质岩形成于陆内构造环境,而非蛇绿岩的组成成分,这对深化区域大地构造研究具有重要意义。     

Apatite-hosted melt inclusions from the Panzhihua gabbroic-layered intrusion associated with a giant Fe–Ti oxide deposit in SW China: insights for magma unmixing within a crystal mush

The ～?2-km-thick Panzhihua gabbroic-layered intrusion in SW China is unusual because it hosts a giant Fe–Ti oxide deposit in its lower zone. The deposit consists of laterally extensive net-textured and massive Fe–Ti oxide ore layers, the thickest of which is ～?60 m. To examine the magmatic processes that resulted in the Fe enrichment of parental high-Ti basaltic magma and the formation of thick, Fe–Ti oxide ore layers, we carried out a detailed study of melt inclusions in apatite from a ～?500-m-thick profile of apatite-bearing leucogabbro in the middle zone of the intrusion. The apatite-hosted melt inclusions are light to dark brown in color and appear as polygonal, rounded, oval and negative crystal shapes, which range from ～?5 to ～?50 µm in width and from ～?5 to ～?100 µm in length. They have highly variable compositions and show a large and continuous range of SiO₂ and FeO_t with contrasting end-members; one end-member being Fe-rich and Si-poor (40.2 wt% FeO_t and 17.7 wt% SiO₂) and the other being Si-rich and Fe-poor (74.0 wt% SiO₂ and 1.20 wt% FeO_t). This range in composition may be attributed to entrapment of the melt inclusions over a range of temperature and may reflect the presence of µm-scale and immiscible Fe-rich and Si-rich components in different proportions. Simulating results for the motion of Si-rich droplets within a crystal mush indicate that Si-rich droplets would be separated from Fe-rich melt and migrate upward due to density differences in the interstitial liquid when the magma unmixed. Migration of the Si-rich, immiscible liquid component from the interstitial liquid caused the remaining Fe-rich melt in the lower part to react with plagioclase primocrysts (An_59–60), as evidenced by fine-grained lamellar intergrowth of An-rich plagioclase (An_79–84)?+?clinopyroxene in the oxide gabbro of the lower zone. Therefore, magma unmixing within a crystal mush, combined with gravitationally driven loss of the Si-rich component, resulted in the formation of Fe-rich, melagabbro and major Fe–Ti oxide ores in the lower part and Si-rich, leucogabbro in the upper part of the intrusion.     

Zircon U–Pb–Hf isotopes and geochemistry analyses of the Huyu igneous rocks in northwestern Beijing,China: possible new evidence for the initial destruction of the North China Craton

The timing and extent of cratonic destruction are crucial to understanding the crustal evolution of the North China Craton (NCC). Zircon U–Pb–Hf isotope data and the whole-rock major and trace element characteristics of the Huyu igneous rocks in northwestern Beijing, China, provide possible new evidence for the initial destruction of the NCC. The igneous rocks occur as several sills and dikes, including lamprophyre, monzonite porphyry, and aplite. The lamprophyres have high Mg^# and K₂O contents. The monzonite porphyries have high Mg^#, high K₂O contents, and negative ε_Hf(t) values with zircon U–Pb ages of 225.5–227.7 Ma. These two types of rocks are both enriched in large ion lithosphere elements (LILEs) and light rare earth elements (LREEs) but are depleted in high field strength elements (HFSEs) and high rare earth elements (HREEs) and have almost no Eu anomalies and relatively high total rare earth element (ΣREE) contents. In contrast, the aplites exhibit high silica and K₂O contents, low MgO contents, and more negative ε_Hf(t) values with a zircon U–Pb age of 206.2 Ma. The aplites are also enriched in LILEs and LREEs but are depleted in HFSEs and HREEs, with strongly negative Eu, Ti, P, La, Ce, and Sr anomalies and relatively low ΣREE contents. These results indicate that the lamprophyres and monzonite porphyries represent a continuous cogenetic magma evolution series after melt derived from an enriched metasomatized lithospheric mantle experienced crust assimilation and fractional crystallization. The aplites were produced by the fractional crystallization of low-Mg parental magma derived from melting of the ancient Archaean crust. The occurrence of the Huyu intrusive rocks with many other plutons of similar ages on the northern margin of the NCC suggests that the northern NCC entered an intraplate extensional tectonic environment in the Late Triassic.