深埋隧洞爆破开挖扰动损伤效应的数值模拟

爆破开挖扰动是深埋隧洞损伤区孕育及演化的重要影响因素。根据隧洞岩体钻爆开挖过程分析了爆炸荷载及开挖荷载瞬态卸荷对岩体的扰动作用,基于LS-DYNA动力有限元程序,提出了利用施加节点反力模拟待开挖隧洞岩体的约束作用,通过控制节点反力的变化过程以模拟开挖荷载瞬态卸荷,采用爆炸荷载变化曲线模拟爆炸作用过程的爆破开挖扰动数值模拟方法,并利用该方法模拟分析了爆破开挖扰动对围岩的损伤效应,结果表明,应力重分布对围岩损伤最大,隧洞围岩损伤区主要由围岩初始应力重分布所导致,爆炸荷载作用将增大围岩损伤区范围,考虑开挖荷载瞬态卸荷作用的围岩损伤区最大,且地应力越高,开挖荷载瞬态卸荷作用对围岩的损伤效应越显著     

不同氧化锰矿物对光催化降解苯酚的影响

合成层状结构的酸性和碱性水钠锰矿以及隧道结构的锰钾矿和钙锰矿,将其用于苯酚的光催化降解研究。分别采用X射线衍射(XRD)、原子吸收光谱(AAS)、扫描电镜(SEM)、BET氮气吸附法和紫外可见漫反射光谱(UV-Vis DRS)对供试锰氧化物的晶体结构、化学组成、微观形貌、比表面积以及光吸收性能等进行了表征。研究表明,暗反应条件锰氧化物对苯酚的降解作用较弱,而UV-Vis光照能显著促进锰氧化物对苯酚的降解。光照反应12 h后,锰钾矿、酸性水钠锰矿、钙锰矿以及碱性水钠锰矿的苯酚降解率分别为92.1%、77.3%、57.4%和45.8%;对应的TOC去除率分别由暗反应时的6.3%、11.2%、2.0%和4.6%提高至62.1%、43.1%、25.4%和22.5%。4种供试锰氧化物均具有光催化活性,其大小顺序为:锰钾矿>酸性水钠锰矿>钙锰矿>碱性水钠锰矿。UV-Vis光照下氧化锰矿物光化学降解苯酚主要存在3种降解机制———苯酚的直接光解,锰氧化物的化学氧化和锰氧化物的光化学催化,其中光催化降解起主导作用。     

云南昭通毛坪铅锌矿床同位素地球化学性质研究

云南昭通毛坪铅锌矿床是滇东北铅锌成矿带中一个典型的中-大型矿床,文章在分析矿区地质特征的基础上,通过对矿床的硫、铅、碳、氢、氧五种同位素的组成特征及其地球化学性质的研究,探讨了成矿流体的性质和来源以及矿床可能的形成方式等问题.     

Characteristics of telemagmatic metamorphism of the Ceshui Formation coal in Lianyuan coal basin

The Ceshui Formation coal is mostly anthracite and its metamorphism has been less documented.By analyzing systematically the reflectance of vitrinite and the results of X-ray diffraction of the Ceshui Formation cola in the Lianyuan coal basin,the spatial variation characteristics of coal ranks,coal metamorphic regions,the extension of coal metamorphic belts.coal metamorphic gradients,coal chemical structure and the effect on the degree of metamorphism of heat-production and -storge conditions,buried depth of the Indosinian-Yenshanian granites at the margins of the Lianyuan coal basin are discussed.The research results in conjunction of the features of regional hydrothermal alterations,endogenetic deposits with the Ceshui Formation coal measures,and the development of secondary vesicles indicate that the telemagmatic metamorphism is the main factor leading to the metamorphism of the Ceshui Formation coal in the region studied.     

The role of metal sulfates in thermochemical sulfate reduction (TSR) of hydrocarbons: Insight from the yields and stable carbon isotopes of gas products

The mechanism of thermochemical sulfate reduction (TSR) was investigated by separately heating n-C₂₄ with three different sulfates (CaSO₄, Na₂SO₄, MgSO₄) in sealed gold tubes at 420 °C and measuring the stable carbon isotope values of hydrocarbon (C₁-C₅) and non-hydrocarbon (CO₂) products. Extensive TSR was observed with the MgSO₄ reactant as reflected by increasing concentrations of H₂S, ¹³C depleted CO₂ and relatively low concentrations of H₂ (compared to the control). H₂S yields were already very high at the first monitoring time (12 h) when the temperature had just reached 420 °C, suggesting that TSR had commenced well prior to this temperature. Only trace amounts of n-C₂₄ and secondary C₃-C₅ alkanes were detected at 12 h, reflecting the efficient TSR utilization of the reactant and lower molecular weight alkane products. Ethane levels were still relatively high at 12 h, but declined thereafter as it was subject to TSR in the absence of higher molecular weight alkanes which had already been utilized. Methane yields were consistently high throughout the 48 h MgSO₄ treatment. The temporal decrease in the concentrations of alkanes available for TSR may also contribute to the sharp enhancement of CO₂ after 36 h. Absence or dampening of the molecular and isotopic trends of MgSO₄ TSR was observed with Na₂SO₄ and CaSO₄ respectively, directly reflecting the levels of TSR reached using these sulfate treatments.For all treatments, the δ¹³C values of C_1-5n-alkanes showed an increase with both molecular weight and treatment time. MgSO₄ TSR led to a 5-10‰ increase in the δ¹³C values of the C₁-C₅ hydrocarbons and a 20‰ decrease in the δ¹³C value of CO₂. The significant ¹³C depletion of the CO₂ may be due to co-production of ¹³C enriched MgCO₃, although this remains unproven as the δ¹³C of MgCO₃ was not measured. The difference in the δ¹³C values of ethane and propane (Δδ¹³C_EP) increased in magnitude with the degree of TSR, and this trend could be used to help evaluate the occurrence and extent of TSR in subsurface gas reservoirs.     

工程勘察数据的传递控制与可视化

从广义说,工程勘察成果中的很大一部分是通过大量数据的传递与处理取得的。数据传递结构的优化和合理控制是提高勘察效率和质量的保证。讨论了用程序编制的方法实现的数据从平面图到剖面图的钻孔距离传递,利用模糊聚类思想提出的对剖面数据进行合并的建议和利用地质三维软件实现的三维地质体模型的耦合展示,这几个问题正是目前大多勘察单位在数据控制与传递流程中可能欠缺的环节。     

河南板厂银多金属矿床钾长石氩-氩年龄及其地质意义

河南内乡板厂矿床通过近年来的勘查工作,为一大型斑岩-热液型银铜铅锌(钼)矿床.本文对该矿床斑岩型铜矿石中钾长石进行了Ar-Ar定年,获得两个年龄坪:900～1150℃年龄坪包括了43.4%的39Ar,坪年龄为(148.1±1.6)Ma,反等时线年龄为(145.7±2.3)Ma;1200～1450℃年龄坪包括了48.8%的39Ar,坪年龄为(161.0±1.6)Ma,反等时线年龄(159.0±14.0)Ma.前者代表了该矿床的成矿年龄,后者代表了含矿斑岩的成岩年龄.该二阶段年龄谱特征反映了板厂矿床成岩成矿的阶段性.在我国不少矿区的Ar-Ar法年龄谱上均有多坪显示,这与我国许多矿区成矿作用和构造事件的多期多阶段特征一致.     

大直径钻孔灌注桩桩身倾斜数值模拟分析研究

本文验证了有限差分法模型模拟大直径钻孔灌注桩的可靠性。在此基础上对某工程灌注桩底部分桩身发生倾斜的情况进行了FLAC3D模拟,分析了其承载力及稳定性的变化,从而得出在一定倾斜范围内,桩的承载力及稳定性变化不会对工程实际产生太大的影响。     

Spatial distribution of surface soil water content under different vegetation types in northwest Guangxi, China

Geostatistical and statistical analyses were combined to examine the spatial distribution of soil water content under four vegetation types during the dry season, in the peak-cluster depression in the karst region in northwest Guangxi, southwest China. The soil water content significantly increased from farmland to plantation, secondary forest, and primary forest; whereas the variation coefficients, the sill (C ₀+C), and total spatial variance increased, although the range decreased. The spatial distribution of soil water content in the different vegetation types had a high spatial autocorrelation. Different models produced a best fit for the semivariograms of the four vegetation types. Elevation and slope position were the primary factors influencing the spatial distribution of soil water content, with other key factors differing between the four vegetation types. Moreover, even though different specific factors influenced soil water content in the four vegetation types, the correlations and degrees of associations between the soil water content and these various factors differed. Therefore, the corresponding strategies for rational usage and management of water resources should be different for the four vegetation types in this region.