爆破震动对土质边坡动力稳定性影响研究

采用拟静力化的惯性力法,利用改进了的条分法来计算主动土压力,并考虑爆破地震的时程效应,提出了已有边坡在爆破过程中的动力稳定性系数的新的计算方法。实例证明,所得计算结果综合考虑了爆破震动波传播过程的衰减、频谱结构及相位差等因素的影响,因此该方法在土质边坡稳定分析中与拟静力法相比更具理论基础,其结果也更接近工程实际。     

珠江三角洲冲积平原土壤氟高含量区形成原因

珠江三角洲经过系统的1∶250000区域土壤地球化学调查发现,在三角洲冲积平原存在氟的高含量分布区。氟高含量区分布于第四纪海相和海陆交互相,从海相→海陆交互相→陆相含量逐渐降低,相同沉积相含量变化很小。从地表至深部,含量变化与沉积相关系密切,海陆交互相含量变化很小,而陆相含量变化较大。氟高含量区空间分布特征明显,控制因素显著,属于在沉积地质作用过程形成的。可能与珠江三角洲形成过程,西江、北江和东江带来大量含氟物质,加上海水富含氟,导致海相和海陆交互相沉积物氟含量较高而出现大面积的高含量区。     

时域反射技术在地学研究中的应用

综合介绍了时域反射技术在地学研究中的应用。包括时域反射仪的工作原理、测量参数(特征阻抗、介电常数、土壤含水量、土壤电导率)、时域反射探针技术以及时域反射技术在农业地质、水文地质、灾害地质等研究中的应用与进展。     

Late Cenozoic Sedimentary Evolution of Pagri‐Duoqing Co graben,Southern End of Yadong‐Gulu Rift,Southern Tibet

The north trending rifts in southern Tibet represent the E–W extension of the plateau and confirming the initial rifting age is key to the study of mechanics of these rifts. Pagri–Duoqing Co graben is located at southern end of Yadong–Gulu rift, where the late Cenozoic sediments is predominately composed of fluvio-lacustrine and moraine. Based on the sedimentary composition and structures, the fluvio-lacustrine could be divided into three facies, namely, lacustrine, lacustrine fan delta and alluvial fan. The presence of paleo-currents and conglomerate components and the provenance of the strata around the graben indicate that it was Tethys Himalaya and High Himalaya. Electron spin resonance (ESR) dating and paleo-magnetic dating suggest that the age of the strata ranges from ca. 1.2 Ma to ca. 8 Ma. Optically stimulated luminescence (OSL) dating showed that moraine in the graben mainly developed from around 181–109 ka (late Middle Pleistocene). Combining previous data about the Late Cenozoic strata in other basins, it is suggested that 8–15 Ma may be the initial rifting time. Together with sediment distribution and drainage system, the sedimentary evolution of Pagri could be divided into four stages. The graben rifted at around 15–8 Ma due to the eastern graben-boundary fault resulting in the appearance of a paleolake. Following by a geologically quiet period about 8–2.5 Ma, the paleolake expanded from east to west at around 8–6 Ma reaching its maximum at ca. 6 Ma. Then, the graben was broken at about 2.5 Ma. At last, the development of the glacier separated the graben into two parts that were Pagri and Duoqing Co since the later stages of the Middle Pleistocene. The evolution process suggested that the former three stages were related to the tectonic movement, which determined the basement of the graben, while the last stage may have been influenced by glacial activity caused by climate change.     

TIGGE降雨信息在柴河流域洪水预报中可利用性评估

基于全球多模式集合预报(TIGGE)资料,以柴河流域为研究区域,采用TS评分、Brier评分和Talagrand分布等方法对欧洲中期天气预报中心(ECMWF)、美国国家环境中心(NCEP)和英国气象局(UKMO)三个中心集合预报的6h、12h、24h短期降雨量进行定量评估和对比,并分别以实测降雨和NCEP预报降雨驱动新安江模型模拟洪水过程,据此探讨了集合降雨预报的可利用性。得到两个重要结论:ECMWF、NCEP和UKMO对低雨量级降雨的预报效果较好,各雨量级的预报效果有随预见期增长而增加的趋势,且普遍存在空报率较高、漏报率偏低的情况;集合降雨预报信息可应用于新安江模型进行洪水预报,并能够有效的延长洪水预报的预见期。研究成果可在适当条件下推广应用至其它流域的洪水预报作业中。     

汉中盆地地下水水化学特征及其成因研究

为研究汉中盆地地下水的水化学特征及成因,在丰水期共采集56件潜水样品,综合运用数理统计、相关性分析、Piper三线图、Gibbs模型和离子比等方法,分析了汉中盆地地下水的水文地球化学特征、各化学参数的空间变化规律、主要离子的控制因素及来源。结果表明,汉中盆地地下水阳离子以Ca2+为主,阴离子以HCO3–为主。从离子空间变化规律上来看, K+波动最为剧烈,且从中下游开始逐渐降低,Cl−和Na+变化规律一致,呈波动变化;HCO3−、Ca2+、Mg2+以及SO42−的从中上游至中下游含量逐步降低,至下游含量增加;TDS值为128.5～590 mg/L,平均值为282.67 mg/L,在中下游含量明显增加;pH平均值为7.17,为弱碱性,在中上游波动剧烈,至下游逐渐降低。地下水水化学类型以HCO3–Ca和HCO3–Ca·Mg型为主,受碳酸盐岩和硅酸盐岩的溶解共同控制,阳离子交替吸附作用较弱,Na+和K+主要来源于钾长石、钠长石等硅铝酸盐矿物的溶解和部分盐岩的风化溶解,Ca2+除来自碳酸盐岩的溶解外,还有大量硅酸盐岩的溶解;方解石及少量白云石等碳酸盐岩的风化溶解对Mg2+和HCO3−贡献较大。查明汉中盆地地下水水化学特征及成因机制,可为汉中地区地下水饮水安全提供有力科学依据。     

大九湖泥炭地现代植物不同组分的δ18O特征及其古气候意义

最初学者利用泥炭植物同位素重建气候变化是参考树轮的研究方法,而树轮中不同组分的同位素对气候变化的响应不同。泥炭地植物不同组分的同位素对气候的响应是否也存在差异,需要进一步探讨和研究。此外,不同泥炭地植物δ¹⁸O的气候学解译存在一定的争议,这些解译的差异要求我们在利用泥炭δ¹⁸O重建古气候时需结合泥炭地现代过程的监测。文章以中国东部季风区的大九湖泥炭地为研究区域,测试研究区现代植被α纤维素与综纤维素的δ¹⁸O,对比两者的分布特征及其在时间序列上的相关性,进而探讨它们对气候因子的响应程度。结果表明：大九湖泥炭地植物δ¹⁸O分布较离散,平均值为25.09‰,α纤维素的δ¹⁸O比综纤维素δ¹⁸O偏正0.79‰~1.06‰,两种组分的δ¹⁸O在季节变化序列上没有明显的相关性。通过与区域气候因子的对比,我们发现温度是影响该地区植物δ¹⁸O变化的主要因素,而且植物α纤维素的δ¹⁸O比综纤维素的δ¹⁸O对温度响应更敏感,植物α纤维素更适用于作为研究古气候变化的载体,这一结果为中国东部季风内将泥炭地植物α纤维素的δ¹⁸O作为温度变化的代用指标提供了实验支持。

     

东营凹陷平南-石村变换构造发育特征及其定量表征

同向超接型变换构造往往是由同向趋近型变换构造发育而来,当主干断裂的叠置部分较大时,其内部会受到与区域
伸展方向一致的局部拉张作用,产生与主干断裂平行的纵向变换断层。根据区域伸展量守恒原理,结合同向超接型变换构
造的发育特征及其主控因素分析,提出了“变换强度”（transfer degree）的计算公式来定量表征变换构造对主干断裂的调节
程度,并将变换强度定义为变换构造的伸展量与主干断层最大水平位移量的比值;为了减小统计过程中的误差,采用了主
干断层及其末端的水平位移为参数进行了变换强度的计算。该文选取了东营凹陷西部的平南-石村同向超接型变换构造为
典型实例进行了分析,并运用平衡剖面技术验证了计算结果的准确性,二者吻合度好,表明该方法具有一定的可行性,为
其他类型变换构造的定量表征提供了一定的思路。     

城市雨水地下回灌过程中悬浮物表面堵塞规律

雨洪资源地下回灌是缓解城市供水压力、解决地下水过量开采引起环境负效应的有效途径之一,但堵塞问题却是制约回灌技术推广的关键问题。基于前人理论,研究了入渗介质与悬浮物粒径中值之比(D₅₀/d₅₀)对堵塞层空间分布的影响。以建立表面堵塞预测模型为目的,利用城市雨水回灌细粒石英砂介质开展室内实验,观测雨水回灌的表面堵塞过程并获取渗透性变化的观测数据。根据物理、化学与生物堵塞的产生条件及堵塞特点,判断雨水回灌产生的堵塞性质为物理堵塞。引入过滤模型描述堵塞的发展过程,确定了模型用于模拟细砂表面堵塞的参数值：孔隙堵塞系数（α）为0.15 m²/kg,阻力增长系数（f′R′）为20 000 m/kg。在不改变以上2个参数值的条件下,用该模型模拟不同悬浮物粒径悬浊水回灌细粒石英砂的堵塞过程,取得了较好的拟合效果。此过滤模型可以用于模拟入渗介质与悬浮物粒径D₅₀/d₅₀值小于5的表面堵塞的发展过程,可定量预测堵塞对回灌速率的影响。     

Dissolved and particulate trace metals and their partitioning in a hypoxic estuary: The Tanshui Estuary in Northern Taiwan

The distribution and partitioning of trace metals (Co, Cu, Fe, Mn, Ni, and Zn) between dissolved and particulate phases were studied in the Tanshui Estuary. The upper reach of the estuary is hypoxic and heavily polluted due to domestic and industrial discharges. The concentration ranges of dissolved and leachable particulate trace metals in the Tanshui Estuary were: Co: 0.3–6.1 nM, 1.8–18.6 mg kg⁻¹; Cu: 5–53 nM, 22–500 mg kg⁻¹; Fe: 388–3,364 nM, 1.08–6.67%; Mn: 57–2,914 nM, 209–1,169 mg kg⁻¹; Ni: 7–310 nM, 6–108 mg kg⁻¹; and Zn: 12–176 nM, 62–1,316 mg kg⁻¹; respectively. The dissolved concentrations of the metals were 2–35 times higher than the average values of the world river water. The distributions of dissolved and particulate studied metals, except Mn, in the estuary showed scattering, which could be attributed to the discharges from many industrial wastewater disposal works located in the upper tributaries. The daily input of dissolved metals from the disposal works to the Tanshui Estuary ranged from 0.1–0.4 tons. Dissolved Mn was nearly conservative in the region with salinity higher than 10 psu, while particulate Mn decreased in the region with salinity of 10–15 psu. The concentration increased significantly seawards, corresponding with the distribution of dissolved oxygen. The distribution coefficient (K_D) for Mn in the lower estuary was nearly three orders of magnitude higher than in the upper estuary. This phenomenon may be attributed to the diffusion of Mn from the anoxic sediment in the upper estuary and gradual oxidation into particulate Mn in the middle and lower estuary as the estuarine water became more oxygenated. The distribution coefficient for Cu decreased with increasing salinity. The percentages of trace metals bound by suspended particulate matter decreased in the following order: Fe>Zn, Cu>Co>Mn>Ni.