基于交错网格有限差分法的断面波叠前时间偏移成像影响因素正演分析

断层和断裂带的有效识别是地震资料解释中的重要环节,断层在地震信号响应中以断面波的形式体现,因此断面波成像的质量关系到断层的精细识别与刻画.本文利用精度较高的交错网格有限差分正演模拟方法对断面波成像的影响因素进行了正演研究,主要正演分析的参数包括采集因素中的电缆长度和采集方向,地质因素中的断层倾角、断距、反射系数,以及处理因素中的偏移方法等几个方面.通过正演论证得出：采用合理的采集参数能够提高断面波的照明度;有效结合地质因素能够提高断面波的解释精度;利用合理的偏移方法能够使断层归位更加准确,断面波有效成像.基于以上结论,对于断面波的精确识别与刻画,应综合采集因素,处理因素及地质因素,只有这样才能提高断层的解释精度,有效减小解释误差.     

基岩倾角对盆地地震响应的影响分析

为了研究盆地基岩倾角对盆地地表动力反应的影响,选取了一个跨度2 km,深度500 m的二维成层盆地为研究对象进行有限元动力反应分析。以持时0.25 s的狄拉克脉冲作为输入地震动,探讨了P波和SV波垂直入射时,盆地基岩倾角从10°\,20°\,30°\,40°依次增加的情况下盆地地震反应。结果表明:入射波在倾斜基岩处发生波型转化,同时产生面波,在盆地中心区域发生汇聚;随着基岩倾角的增加地表中心处的卓越频率有减小的趋势。     

城市钻孔数据地下三维地质建模软件的实现

介绍了基于钻孔数据的城市地下三维地质建模软件的实现过程，提出了基于钻孔数据三维地质建模的总体思路、钻孔数据管理和层序分层方法，还介绍了软件的模块组成及应用实例。建立的软件实现了对城市钻孔数据的三维建模、可视化分析和科学管理，具有丰富的二维成图和三维显示功能，实例的应用也说明本软件是分析城市第四系构造格架和演化的有力工具。     

A sensitivity of squall-line intensity to environmental static stability under various shear and moisture conditions

Squall lines develop in various climate regions having diverse environmental profiles of wind shear, moisture, and temperature. In order to explore the sensitivity of squall lines to these environmental profiles, we have performed an extensive set of numerical simulations under various shear and moisture conditions in midlatitude-continental and tropical–oceanic temperature environments. From the results of the sensitivity simulations and the analyses of the environmental parameters, it is found that the static stability in a convectively unstable layer is of primary importance in determining the strength of squall lines. Under temperature environments having the same static stability, convective available potential energy (CAPE) and precipitable water content (PWC) well describe the squall-line intensity. Vertical shear also plays an important role in determining the squall-line structure as well as the intensity through the interaction with surface cold pool. The combination of the static stability in a convectively unstable layer, CAPE, and PWC should be examined in diagnosing the intensity of squall lines that develop with an optimal shear for their environment.     

结合边界条件的截断高阶隐式有限差分方法(英文)

有限差分方法广泛应用于求解许多科技领域所涉及的偏微分方程,高阶显式有限差分方法通常用来提高求解精度,已经提出的高阶隐式有限差分方法和截断高阶显式有限差分方法可用来进一步提高模拟精度而不增加计算量。本文首先计算了针对常规网格上的一阶导数和二阶导数、交错网格上的一阶导数的有限差分系数,发现高阶隐式有限差分系数中存在一些小的系数。频散分析结果表明:忽略这些小的差分系数能够近似维持有限差分的精度,但是显著减小了计算量。然后,引入镜像对称边界条件来提高隐式有限差分方法的精度和稳定性,采用混合吸收边界条件来减小来自模型边界所不需要的反射。最后,给出了针对均匀和非均匀介质模型的弹性波模拟例子,表明了本文方法的优点。     

Meso‐Cenozoic Tectonothermal History of Permian Strata,Southwestern Weibei Uplift: Insights from Thermochronology and Geothermometry

This study provides an integrated interpretation for the Mesozoic-Cenozoic tectonothermal evolutionary history of the Permian strata in the Qishan area of the southwestern Weibei Uplift, Ordos Basin. Apatite fission-track and apatite/zircon(U-Th)/He thermochronometry, bitumen reflectance, thermal conductivity of rocks, paleotemperature recovery, and basin modeling were used to restore the Meso-Cenozoic tectonothermal history of the Permian Strata. The Triassic AFT data have a pooled age of ～180±7 Ma with one age peak and P(χ2)=86%. The average value of corrected apatite(U-Th)/He age of two Permian sandstones is ～168±4 Ma and a zircon(U-Th)/He age from the Cambrian strata is ～231±14 Ma. Bitumen reflectance and maximum paleotemperature of two Ordovician mudstones are 1.81%, 1.57% and ～210°C, ～196°C respectively. After undergoing a rapid subsidence and increasing temperature in Triassic influenced by intrusive rocks in some areas, the Permian strata experienced four cooling-uplift stages after the time when the maximum paleotemperature reached in late Jurassic:(1) A cooling stage(～163 Ma to ～140 Ma) with temperatures ranging from ～132°C to ～53°C and a cooling rate of ～3°C/Ma, an erosion thickness of ～1900 m and an uplift rate of ～82 m/Ma;(2) A cooling stage(～140 Ma to ～52 Ma) with temperatures ranging from ～53°C to ～47°C and a cooling rate less than ～0.1°C/Ma, an erosion thickness of ～300 m and an uplift rate of ～3 m/Ma;(3)(～52 Ma to ～8 Ma) with ～47°C to ～43°C and ～0.1°C/Ma, an erosion thickness of ～500 m and an uplift rate of ～11 m/Ma;(3)(～8 Ma to present) with ～43°C to ～20°C and ～3°C/Ma, an erosion thickness of ～650 m and an uplift rate of ～81 m/Ma. The tectonothermal evolutionary history of the Qishan area in Triassic was influenced by the interaction of the Qinling Orogeny and the Weibei Uplift, and the south Qishan area had the earliest uplift-cooling time compared to other parts within the Weibei Uplift. The early Eocene at ～52 Ma and the late Miocene at ～8 Ma, as two significant turning points after which both the rate of uplift and the rate of temperature changed rapidly, were two key time for the uplift-cooling history of the Permian strata in the Qishan area of the southwestern Weibei Uplift, Ordos Basin.     

引红济石引水隧洞围岩力学特性研究

引红(红岩河)济石(石头河)引水隧洞围岩断层带破碎松软,岩石强度低,自稳能力差,易产生大变形。以上不良地质条件使其隧洞施工过程中经常会遇到TBM卡机等一系列特殊问题。针对引红济石引水隧洞施工中存在的软岩隧洞大变形问题,首先开展了X射线衍射、崩解试验,分析了试样的组成成分、黏土矿物含量对崩解性影响;再通过一系列单轴压缩试验、三轴压缩试验和蠕变试验研究了该类岩石不同应力条件下的变形破坏特征及蠕变特性。试验结果表明,该类岩石含有大量的黏土矿物(33.49%),对水比较敏感,遇水膨胀易崩解,导致岩体软化;试样具有较大塑性压缩变形,其应力-应变曲线为应变强化型,且没有明显的峰值。基于试验研究成果和现场监测数据,对该软岩隧洞大变形机制进行了分析,并提出了在围岩与管片之间安装聚氨酯缓冲层的新型支护方案,通过数值计算对支护方案的合理性进行了验证。分析结果表明:聚氨酯缓冲层可以很好地吸收围岩形变压力,避免应力集中带来的管片错台,从而大大减小管片上破坏区的产生。研究成果对该类岩体中隧洞的设计施工以及长期稳定性分析具有重要的参考作用。     

结构方程模型及其在地学数据建模中的回顾与展望

结构方程模型是一种建立、 估计和检验因果关系的方法.它可以替代多重回归、 路径分析、 因子分析、 协方差分析等方法,清晰分析单项指标对总体的作用和单项指标间的相互关系,是一种主要应用于验证性模型分析的多元统计建模技术.由于能够通过可观测变量来度量潜变量得分以及分析不同子模型下潜变量之间的协同效应等优点,结构方程模型被广...     

基于决策树特征提取的支持向量机在岩性分类中的应用

由于支持向量机属于黑箱模型,因此在进行模型学习时无法直接对特征进行选择,而决策树模型在递归创建的过程中自身具有一定的特征选择能力。针对岩性分类问题,本文将决策树和支持向量机结合,通过决策树的建立,在考虑特征重要性的前提下,利用树节点的高度对特征进行提取,并将具有更高分类能力的特征送入支持向量机进行岩性分类。结果表明:通过决策树的特征提取,减少了支持向量机模型的输入特征,从而有效控制了模型的复杂度,使得模型更加稳定并具有更高的分类精度,测试集精度能够提升10%以上。