高速公路混凝土路面板底脱空化学灌浆治理方法

结合工程实例阐述了高速公路混凝土路面板底脱空成因,介绍了板底脱空的判定方法和化学灌浆治理施工工艺。     

地下洞室超欠挖问题非线性有限元分析

运用数值分析的方法,采用ANSYS10.0版有限元分析程序对洞室超欠挖进行三维模拟计算,分析了不同超挖位置、超挖深度、超挖数量等对洞室围岩稳定性的影响,得出了超欠挖部位应力集中数值解及塑性区产生的影响范围,为地下工程掘进施工和初期支护设计提供重要的参考依据。     

港湾广场（一期）深基坑变形监测与分析

深基坑施工变形监测是信息化施工的重要内容,以广州港湾广场(一期)深基坑工程为例,通过对开挖过程中土体水平位移、支护结构侧向位移、支护结构内应力、沉降等监测,结合围护结构的强度检测,采用反演分析对基坑变形进行数值模拟,预测不同开挖深度时基坑的位移变形量,实际监测结果与预测值基本一致,为基坑的设计和施工提供可靠的依据。     

High Precision Time Domain Forward Modeling for Crosshole Electromagnetic Tomography

To improve the resolution of crosshole electromagnetic tomography, high precision of forward modeling is necessary. A pseudo-spectral time domain (PSTD) forward modeling was used to simulate electromagnetic wave propagation between two boreholes. The PSTD algorithm is based on the finite difference time domain (FDTD) method and uses the fast Fourier transform (FFT) algorithm for spatial derivatives in Maxwell's equations. Besides having the strongpoint of the FDTD method, the calculation precision of the PSTD algorithm is higher than that of the FDTD method under the same calculation condition. The forward modeling using the PSTD method will play an important role in enhancing the resolution of crosshole electromagnetic tomography.     

Hydrogeochemical processes of thallium in a rural area of Southwest Guizhou, China

The water system in a rural area of Lanmuchang in Southwest Guizhou is facing a risk of thallium (Tl) contamination due to Tl mineralization around the area. The major trace elements and Tl in the water system are studied to understand the hydrogeochemical processes of Tl constrained by Tl mineralization. The results showed that the dispersion pattern of Tl follows a descending order in concentration from mine groundwater (deep groundwater) →stream water→shallow groundwater→background water, reflecting the impact of Tl mineralization on the hydrogeochemical composition. Tl concentrations in stream water in both regimes are remarkably higher (2-30 fold) downstream than up- and mid-streams, probably caused by the unidentified discharge of deep groundwater. Low Tl levels are detected in the current drinking water, however, the highly elevated Tl in stream water and ground water may pose a potential environmental risk through daily washing and agricultural irrigation. This study suggests that human activities, such as agricultural irrigation, could intensify the environmental risk of Tl.     

Geochemical characteristics of crude oils from Well Zheng-1 in the Junggar Basin, Xinjiang, China

Well Zheng-1 is located in the combined area of the central uplift and the north Tianshan piedmont depression in the Junggar Basin. Two oil-bearing beds are recognized at 4788–4797 m of the Lower Cretaceous Tugulu Formation (K1tg) and 4808.5–4812.5 m of the Lower Jurassic Sangonghe Formation (J1s). The geochemical characteristics of family composition, carbon isotopic composition, saturated hydrocarbons, sterane and terpane biomarkers and carotane of two crude oils are described in this paper. The results show that the geochemical characteristics of the two crude oils are basically similar to each other, indicating they were all derived mainly from the high mature, brine, algae-rich lake facies sediments. Oil-source correlation revealed that crude oils of the two beds were derived mainly from the source rocks of Permian and mixed by the oil derived from the source rocks of Jurassic and Triassic. This is consistent with the geological background with several sets of source rocks in the area studied.     

碳酸盐岩有机质二次生烃的化学动力学研究及其意义

对低成熟度的灰岩样品进行人工熟化实验, 获得了不同成熟度的可用于对比研究二次生烃作用的系列样品. 之后, 将人工熟化后的样品在抽提前、后分别置于Rock-Eval热解仪上进行“二次”生烃实验, 在考察其热解产率特征的同时, 探讨各样的化学动力学特征. 结果表明, 二次生烃的是否“提前”或“滞后”及二次生烃潜力与一次生烃是否排出有关, 与初次成烃的中止成熟度有关. 人工熟化样品抽提后, 其平均活化能随成熟度的升高总体上呈增大趋势. 但未经抽提样品的动力学特征则相反. 所标定的经抽提处理和不经抽提处理化学动力学模型在渤海湾盆地和松辽盆地的初步应用表明, 两者的结合可以解释一些前人有关二次生烃研究中存在的相互矛盾的认识, 同时也可以方便地实现对二次生烃量的定量评价.     

青藏高原木苟日王新生代火山岩地球化学及Sr-Nd-Pb同位素组成——底侵基性岩浆地幔源区性质的探讨

藏北羌塘木苟日王新生代火山岩主要岩石类型为玄武岩和安山玄武岩，地球化学研究表明该套岩石表现出低SiO₂（51～54%），高Mg、Cr和Ni等幔源岩浆的特征;岩石轻稀土中度富集,具弱负铕异常,发育Nb、Ta、Ti等高场强元素的负异常.其低的Sm/Yb值（Sm/Yb = 3.07 ～ 4.35）表明它们应来源于软流圈地幔尖晶石二辉橄榄岩的局部熔融.岩石87Sr/86Sr = 0.705339 ～ 0.705667， ²⁰⁸Pb/²⁰⁴Pb = 38.8192 ～ 38.8937， ²⁰⁷Pb/²⁰⁴Pb = 15.6093 ～ 15.6245，²⁰⁶Pb/²⁰⁴Pb = 18.6246 ～ 18.6383，而¹⁴³Nd/¹⁴⁴Nd = 0.512604 ～ 0.512639，ε_Nd 值近于0（＋0.02～ －0.66），与典型的地幔端元BSE（地球总成分点）十分类似.岩石Δ8/4Pb＝66.82～74.53，△7/4Pb＝9.88～11.42，ΔSr>50，具典型的DUPAL异常,这些地球化学特征表明木苟日王高钾钙碱性基性火山岩可能源于受俯冲流体交代的亲冈瓦纳软流圈地幔的部分熔融.结合该区新生代高钾钙碱性中酸性火山岩地球化学和地球物理资料,文中进一步提出,由于拉萨地块的北向俯冲作用,俯冲流体交代软流圈地幔诱发其部分熔融形成以木苟日王火山岩为代表的高钾钙碱性基性岩浆,这些基性岩浆对羌塘地块岩石圈的底侵作用对于羌塘地块新生代埃达克质高钾钙碱性中     

阿中地块北缘库木达坂岩体群特征及锆石U-Pb测年

分布于阿中地块北缘中浅变质岩隆起带之上的库木达坂岩体(群),为一规模较大的复式岩体,不同岩石类型之间接触关系清楚,由早到晚其侵位顺序为细粒黑云二长花岗岩→中粒含斑黑云二长花岗岩。岩石地球化学资料研究证明,该岩体群与大陆岛弧型花岗岩(CAG)相似,显示壳源花岗岩特点,岩体群中获得(449.7±5.8)Ma的单颗粒锆石U-Pb年龄值,确定该岩体群侵位时代为晚奥陶世,岩体形成可能与红柳构—拉配泉早古生代洋壳向南俯冲相关。     

浙江土壤地球化学基准值与环境背景值

以浙江省农业地质环境调查取得的区域地球化学资料(2002—2004年)为依据,遵循地球化学背景值的基本概念,根据成土母质类型将土壤地球化学基准值划分成13个统计单元,土壤环境背景值以浙北杭嘉湖与宁绍平原、浙东沿海温黄与温瑞平原、浙中金衢盆地区统计单元,在反复剔除异常数据后,获得了52种元素(氧化物)的平均值、标准离差和变异系数,为区域土壤环境质量标准的制订、土壤污染评价和治理修复提供了重要的地球化学依据。