Interpretation of residual gravity anomaly caused by simple shaped bodies using very fast simulated annealing global optimization

A very fast simulated annealing（VFSA） global optimization is used to interpret residual gravity anomaly.Since,VFSA optimization yields a large number of best-fitted models in a vast model space;the nature of uncertainty in the interpretation is also examined simultaneously in the present study.The results of VFSA optimization reveal that various parameters show a number of equivalent solutions when shape of the target body is not known and shape factor ＇q＇ is also optimized together with other model parameters.The study reveals that amplitude coefficient k is strongly dependent on shape factor.This shows that there is a multi-model type uncertainty between these two model parameters derived from the analysis of cross-plots.However,the appraised values of shape factor from various VFSA runs clearly indicate whether the subsurface structure is sphere,horizontal or vertical cylinder type structure.Accordingly,the exact shape factor（1.5 for sphere,1.0 for horizontal cylinder and 0.5 for vertical cylinder）is fixed and optimization process is repeated.After fixing the shape factor,analysis of uncertainty and cross-plots shows a well-defined uni-model characteristic.The mean model computed after fixing the shape factor gives the utmost consistent results.Inversion of noise-free and noisy synthetic data as well as field data demonstrates the efficacy of the approach.

Fast forward modeling of gravity anomalies for two-dimensional bodies of arbitrary shape and density distribution

A fast and high precision spatial domain algorithm is presented for forward modeling of two-dimensional(2D)body gravity anomalies of arbitrary shape and density distribution.The new algorithm takes advantage of the convolution properties of the expression for 2D gravity anomalies,uses a rectangular cell as a grid subdivision unit,and then 2D bodies with irregular cross-sections are approximated by a combination of 2D bodies with a rectangular cross section.The closed-form expression is used to calculate the gravitational anomalies of the combination of 2D bodies with a rectangular cross section.To improve computing effi ciency,the new algorithm uses a fast algorithm for the implementation of the Toeplitz matrix and vector multiplication.The synthetic 2D models with rectangular and circular cross-sections and constant and variable densities are designed to evaluate the computational accuracy and speed of the new algorithm.The experiment results show that the computation costs less than 6 s for a grid subdivision with 10000×10000 elements.Compared to the traditional forward modeling methods,the proposed method significantly improved computational effi ciency while guaranteeing computational accuracy.

Small-scale area survey and analysis of Xinjiang's coal field fire in China

In this paper, Xinjiang＇s coal field is selected as the investigation area. Through a series of field surveys in Xinjiang, we made the small-scale area analysis of coal field fire using the ground remote sensing technique, and presented the reasonable evaluation of thermal anomaly conditions of Xinjiang＇s coal field arising from coal self-ignition fires. The results show that the method of small-scale area analysis is available for examining the extinguished actuality of coal fires and detecting fire spots. Therefore, for the selected fire-extlngulshed coal field in Xinjiang, the fire extinguishing effect was effectively analyzed by the means, and the new hidden thermal dangers were sought and diagnosed. For the coal field where the fire has not been extinguished, the utilization of this means approximately identified the severity and range of the fire area, and provided the quantitative and ground references for extinguish engineering.

基于分层的体域网异常数据检测方法

针对无线体域网(wireless body area network,WBAN)异常数据检测方法忽视人体异常数据的连续性,缺乏异常数据集检测等问题,提出一种基于Hampel滤波器和DBSCAN分层的WBAN异常数据检测方法。根据时间相关性利用Hampel滤波器检测异常数据点,保证数据的连续性,使用改进的基于滑动时间窗的DBSCAN算法,检测异常数据集。实验结果表明,所提方法和其它方法相比,实现了分层的异常数据检测,在保证检测精度的同时准确标注出了异常数据集,具有空间复杂度小的优势。

OCTEM法探测地下空间地质病害体的应用研究

城镇地下空间地质病害体造成地面塌陷事故时有发生,对人民群众的生命财产安全构成巨大威胁。采用地球物理方法探测和预报地下空间地质病害体是预防城镇地面塌陷事故的重要方案。瞬变电磁法(TEM)是探测地下空间地质病害体的重要方法之一。等值反磁通瞬变电磁法(OCTEM)采用免接地、小体积、弱耦合的收发一体小型天线,便于在城镇硬化地面及施工空间受限的场地进行快速探测。本文结合理论计算和实际应用来研究OCTEM对地下地质病害体的探测能力。首先基于矢量有限元实现OCTEM三维正演,研究不同地电类型地质病害体的OCTEM响应特征。根据地下地质病害体的电性特征,构建了纯低阻型、纯高阻型、低阻-高阻复合型3类地质病害体地电模型,对比分析不同地电类型的地质病害体的异常响应,并计算包含地质病害体时的响应与不包含地质病害体时的背景响应之间的相对异常。计算结果表明:OCTEM对纯低阻型和低阻-高阻复合型地质病害体比较敏感,对纯高阻型地质病害体相对不敏感。对于低阻型或低阻高阻复合型地质病害体,低阻部分与围岩电阻率差异越大、厚度越大、埋深越浅,则相对异常越大,越容易被探测。随着深度加大,OCTEM探测分辨能力将减小。最后,通过在湖南浏阳某村镇试验剖面探测地下岩溶地质病害体案例,分析OCTEM的探测效果。

A组煤底板灰岩地质异常体地震响应特征研究

淮南矿区A组煤的安全高效开采是保证华东地区能源供应的重要前提,准确掌握地下煤层的构造形态、发育情况是安全生产和减少事故发生的必要条件。以张集矿1613A工作面为工程背景,采用被动成像和噪声成像技术,对工作面顶底板的微地震监测资料进行分析,工作面已注浆治理的断层破碎带附近微地震事件较多,最深达到工作面下方约80 m的位置,有效验证了该断层破碎带的存在。通过反演的方法分析检波器中接收到的波形信号,获取工作面附近的波速场信息;利用西二、西三_(1)煤采区三维偏移数据体,计算了多种属性,研究了已揭示地质异常体的地震响应特征和属性特征,发现本区构造与地质异常体的研究需要特别注意蚂蚁体、最大曲率、最小曲率、局部异常、落差5个属性的指示作用。研究表明,以三维偏移数据体为基础,提取的各个属性对大断层均有显示,能够进行有效解释;对落差较小断层显示较好的属性是蚂蚁体属性和最大曲率、最小曲率、局部异常、落差属性。

土壤地球化学测量在陕西石泉县迎丰地区金矿勘查中的应用

迎丰地区位于陕西石泉—旬阳国家级金矿整装勘查区内,成矿地质条件和找矿前景良好。通过开展1∶2.5万土壤地球化学测量,对10种元素进行变异系数、相关性分析、聚类分析,结果显示:Au异常分布不均匀,离散程度较大,为主要成矿元素。通过对Au异常和综合异常的研究,结合成矿地质条件和矿化特征,圈出金蚀变带5条。通过地化剖面、槽探、钻探工程验证,共圈出17条金矿(化)体,进一步证实该地区找矿前景良好。

电法勘探新技术在隧道工程地质勘察中的运用实践

隧道由于地质条件复杂、不良地质体发育等特点,一直是工程地质勘察中的一大难题。因此,查明隧道轴线穿越的岩溶、断层破碎带、滑坡堆积体等不良地质体,划分隧道轴线附近围岩级别,对隧道选线及钻孔布设具有重要的指导意义。而电法勘探是地球物理勘探中的重要手段之一,本文分析了电法勘探新技术(高密度电法-分布式、等值反磁通瞬变电磁法、音频大地电磁法、全航空大地电磁法、广域电磁法)对于不良地质体探测的电性异常特征,判释了隧道轴线附近的围岩级别。研究结果表明:充分利用电法勘探新技术,研究隧址区范围内不良地质体与地球物理电性异常特征之间的关系,可有效查明不良地质体的产状、规模及性质,划分围岩级别是有效可行的,可为隧道设计提供科学的地质资料。

大功率激电测量在辽宁阳沟金矿床勘查中的应用

阳沟金矿床地处辽东古元古代裂谷北部与太子河-浑江拗陷带接壤部,该区老地层发育且存在铜、铅、锌等综合化探异常,受地表植被影响找矿工作进展缓慢。区内岩矿石极化率和电阻率差异明显,具备利用电性特征进行大功率激电测量的地球物理勘探条件。通过于区内开展大功率激电测量工作,圈定低阻高极化异常区3个、高阻高极化异常区1个。A异常区内探槽和钻探验证工程均显示出良好的矿化信息,圈定出矿石品位较高、长度超过100 m、宽0.3~0.91 m的矿体1条。大功率激电测量在辽宁阳沟金矿床勘查圈定有利成矿地段、寻找隐伏矿体工作中可发挥重要的作用。

An Expression for Gravity Generated by an Anomalous Geological Body and Its Application in Bathymetry Inversion

The gravity anomaly and vertical gravity gradient due to anomalous geological bodies are mainly computed by numerical methods,so it is difficult and time-consuming to use the gravity-geological method to invert seafloor topography.This paper addresses this issue by deriving an expression for gravity generated by a cylinder based on a series expansion.The choice of number for terms in the series is estimated by comparing with the numerical method,especially when the depth H=4000m,the accuracy of 1 mGal(1 Gal=10^(-2)m/s^(2))can be achieved when the series are 9.The expressions can be used to establish the relationships between the shape of an anomalous body and the generated vertical gravity and vertical gravity gradient,respectively.Finally,the potential applications of the expressions in inverting seafloor topography are illustrated by synthetic examples.

Analysis of Sacks Body Strain Interference at Beida No.200 Station in Changping and Earthquake Case Study

The relationship between Sacks body strain deformation at Beida No. 200 station in Changping and tidal solids,atmospheric pressure and water level is analyzed in this paper. Sacks body strain deformation data before the M_S8. 0 Wenchuan earthquake is studied based on the analysis of the interference. The short-impending anomaly of the body strain deformation is considered to be reliable. The anomaly characteristics conclude:( 1) The trend anomaly as extensional change of the body strain deformations on a quasi 1 year time scale before the Wenchuan earthquake was recorded, and the accumulative amount was about 4000 × 10^(-9). Correspondingly,the short-term precursor of earthquake was manifested as an extensional abrupt change.( 2) The extensional intermittent anomalous abrupt change was recorded by body strainmeters between March1 and May 7 in 2008.( 3) Four compressional abrupt changes were recorded in the intermittent distortions recorded between April 13 and May 11.( 4) High frequency components were increased in the distortion process in May 1 to 3,5,7,and 9 to 12,caused by slow earthquakes before the Wenchuan earthquake according to wavelet analysis. The abnormal phenomena are summarized and the mechanics discussed in this paper. Strain solid tide distortions in body strain observations,the continuous repeated extensional and compressional abrupt changes accompanying these distortions,and the increase of high frequency components can be regarded as the index of short term and impending earthquake prediction,based on analysis of interference factors such as air pressure and water level.

Application of Audio-Magnetotelluric Method for Exploration the Concealed Ore-Bodies in Yuele Lead-Zinc Ore Feild, Daguan County, NE Yunnan Province, China

The results of recent mineral exploration in the Yuele lead-zinc mining area of Daguan County, northeastern Yunnan province, showed that there are much early Paleozoic strata under thick late Paleozoic strata in northeastern Yunnan province, where developed some hidden salt structures (SSs), often with lead-zinc polymetallic mineralization varying degrees along the tension torsional fault (belts) or fracture (joint). The ore-bodies belong to the epigenetic hydrothermal filling vein-type deposit, and the prospecting potential is great. In this area, the superficial mineralization information displayed clear, but the deep mineralization is unknown, so the exploration work is restricted. The audio-megnetotelluric (AMT) surveying is an advantageous method to characterize the size, resistivity and skin depth of the polarizable mineral deposit concealed beneath thick overburden. This paper presents the surveying results using AMT method to evaluate the concealed lead-zinc mineralization in Yuele lead-zinc ore field, Daguancounty, NE Yunnan province, China. After comparing the interpretation result of AMT surveying data with the geological data and the drilling data, it is found that there is some distinct difference in resistivity and polarizable between ore-bodies hosted strata, upper strata and gypsum strata. The results show that AMT method is helpful to identify lead-zinc mineralization under this geological condition.

地质异常区域多工作面开采结构演化及冲击地压防治

针对某矿地质异常体区域多工作面开采覆岩空间结构多变、致灾因素复杂现象,以该矿实际地质赋存条件和开采技术条件为工程背景,采用理论分析、数值模拟等方法,研究了地质异常体区域覆岩空间运移结构变化规律和支承压力分布特征,以单层弯曲薄板为例建立了不同开采阶段板的力学模型,揭示了不同开采阶段板结构弯曲能量释放特征,基于结构调控理论提出了减小厚硬岩层垮断跨度的初末采冲击地压防治措施,主要得到以下结论:(1)随着多工作面依次开采,在地质异常体区域依次经历了“一”字形→“S”形→短“Ω”形→不规则“Ω”形→长“Ω”形→“O”形覆岩空间结构演变,丰富了覆岩空间结构的类型;(2)受地质异常体影响,多工作面开采过程中承受了更多次的初次来压和“见方”来压,该区域顶板垮断动载扰动与支承压力分布更加复杂多变,容易造成工作面宽煤柱整体失稳性冲击危险;(3)基于单层弯曲薄板力学模型,得到了不同板结构弯曲能随边长呈指数或线性增大,且相对于固支边,自由边对弯曲能影响更大的结论;(4)对防冲预卸压及解危措施进行了效果检验,在工作面开采过程中没有出现微震大能量事件且煤体应力维持稳定,结构调控措施基本保障了地质异常体区域多工作面开采初末采冲击地压防治效果。

基于疏利少阳法探讨慢性肾脏病继发高血压中医诊疗

目前,继发高血压在慢性肾脏病患者中常见。由于继发高血压影响着患者生命质量和疾病转归,因此要找到合理有效的降压方法。考虑到中药方剂在临床诊疗的独特优势,基于中医学整体观念和治病求本的思想,提出津液代谢障碍作为慢性肾脏病继发高血压的中心环节,并提出应用黄文政教授所创疏利少阳法来治疗,为慢性肾脏病继发高血压的中医诊疗提供新思路。

面向非规范化数据源的动物体温异常识别方法

在动物体温异常识别中,红外测温等方式容易产生系统偏差使得判断结果不可靠。基于深度学习的方法在不同测温设备上的鲁棒性与泛化性能较差,且难以应用于数据量少、随机性强、标准不一致等非规范化的测温场景。因此,本文提出了一种面向非规范化数据源的动物体温异常识别方法,通过衡量体温时序数据间的相似度即可完成异常识别。针对常用的相似性度量算法在序列匹配、序列间距度量上效果不佳的问题,提出了一种改进的动态时间规整算法(Improved dynamic time warping,iDTW)。在点间度量方式上,综合欧氏距离和一阶导数,改善了序列过度对齐问题。使用序列交并比表示序列整体特征,提升了序列间距度量效果。针对不等长序列及过长序列的异常检测问题,提出了基于滑动窗口和序列等分的异常检测方法。以较短序列为滑动窗口遍历较长序列得到一组序列间距,根据训练和检测的不同阶段分别选择其中的最小值或最大值作为相似度衡量结果,以解决不等长序列匹配问题。将过长的样本数据序列等分为多个子序列,取子序列的间距和为样本间距,以解决过长序列导致的正常样本间距过大和异常漏检问题。在公开数据集UCR上的实验分析表明,相比于欧氏距离、动态时间规整、一阶导数动态时间规整和权重动态时间规整算法,iDTW算法结合K-近邻分类器得到的分类准确率在10个UCR数据集上分别平均提高6.0、3.0、5.2、2.5个百分点。基于滑动窗口和序列等分的异常检测方法相比于经典异常检测算法,在3种动物体温数据集上的F1值均获得了明显提升。

基于深度学习的2D-3D地下密度异常体反演方法

地下密度异常体反演需要由二维数据反演三维结果,为了高效、高精度地反演地下异常体的位置及密度信息,本文提出2D-3D InvNet深度学习反演方法.方法的编-解码器结构,在编码阶段利用二维卷积网络结构提取地表重力异常及重力梯度异常数据信息,解码阶段利用三维卷积网络结构恢复异常体地下形态,实现了二维和三维网络结构的结合.为了精确地反演异常体密度,提出利用加权均方误差(WtdMSE)作为损失函数,同时为了更好地评估反演结果,引入核密度函数作为评价手段.与均方误差(MSE)相比,利用WtdMSE作为损失函数对异常体密度的反演结果更为准确,异常体所在区域的密度误差减少50%以上.对理论样本的反演结果表明,2D-3D InvNet在准确反演异常体地下位置的同时,也能给出准确的密度信息.应用此方法对西澳大利亚Kauring地区实测数据进行反演,我们成功获得了此区域地下异常体的密度分布.理论与实际应用结果表明,2D-3D InvNet深度学习方法稳定且具有较强的泛化性能,能在无需规定限制条件的情况下快速获得准确的反演结果.

青海省都兰县色日金银矿床地质、化探异常特征及地质意义

在对色日金银矿床进行相关资料综合研究的基础上,分析了矿床成因类型和不同比例尺化探异常特征,并探讨了其地质意义。研究结果表明:金、银矿体与矿区内大面积分布的印支晚期花岗岩时空关系密切,金矿体主要受北东向断裂控制,银矿体主要受近东西向断裂控制,金、银矿体产生明显分异,表明二者为不同成矿期(阶段)的产物。不同比例尺(1∶20万、1∶5万、1∶2.5万)化探测量圈定的综合异常除主成矿元素Au、Ag外,Sn、Co、Ni、Pb、Zn、As、Sb、Mo、Bi等共生或伴生元素较发育,少数综合异常以共生或伴生元素为主。1∶2.5万化探异常中,金矿化近矿异常以Au(Ag、As)为主,远矿异常通常出现Sn、Co、Ni、Pb、Zn、As、Sb、Mo、Bi等其中几种元素组合,而Au异常较弱;银矿化近矿异常以Ag或Ag、Pb组合异常为主。1∶2.5万化探远矿异常与矿化带的空间位置并不吻合,应根据异常区地形及水系发育情况向山顶及水系上游进行追索找矿。

内蒙古敖其格敖包地区土壤地球化学特征及找矿效果

敖其格敖包地区位于二连浩特—锡林浩特成矿带上,具有良好的找矿潜力。在1∶2万土壤地球化学测量的基础上,对敖其格敖包地区的地球化学特征进行了初步分析,对元素分布特征、Au异常特征、综合异常特征进行了研究。结果显示:Au分布不均匀,离散程度较大,为敖其格敖包地区的有利成矿元素。根据元素组合特征及成矿地质条件,圈出综合异常4处。通过槽探工程查证,圈定了3条矿(化)体,为下一步的地质勘查工作提供了依据。

Characterization of Near Surface Intrusions in South-West Cameroon Zone Using Gravity Data: Mining and Geothermal Implications

The succession of tectonic phenomena in the South-West Cameroon area suggests that structures from the upper mantle infiltrated and took advantage of the cracks and fractures left by these phenomena to get closer to the earth’s surface. However, the intrusive structures closest to the surface remain poorly known. The objective of this work is to improve the knowledge related to the interpretation of gravity data in order to characterise the near-surface intrusive bodies in the South-West Cameroon area, and then analyse their mining and geothermal implications. To achieve this objective, the indirect, inverse and normalized standard deviation (NSTD) methods were used. The NSTD method was used to detect the contours of the intrusive bodies. The indirect method (spectral analysis) was used to determine the depths of the interfaces of three intrusive bodies, one located on the Bipindi-Ebolowa I axis (G5), the other on the Eseka-Pouma axis (G8) and the last on the Bokito-Monatele axis (G11). The results obtained show roofs located between 0 and 0.61 km, between 0 and 0.37 km and between 0 and 0.73 km for the G5, G8 and G11 bodies, respectively. Finally, the application of the 2D inversion method allowed us to estimate the density contrasts of the intrusive bodies (G5, G8 and G11). The superposition of the intrusive bodies detected by the NSTD with the geological and mineral resources map, as well as an analysis of the results obtained, gave indications of interesting zones for mining prospecting and for the search for geothermal reservoirs.

随掘超前探测技术在掘进巷道中的应用

在巷道工作面掘进施工过程中,常常会遇到各种异常地质状况,为保障矿井工作面掘进安全,必须查明巷道前方地质异常体的位置、影响程度和影响范围。以黄陵一号煤矿626回风顺槽随掘超前探测为例,简述了随掘超前探测技术的基本原理、施工方法以及布置方式,探讨了该技术在探测巷道前方异常体中的应用。该技术利用掘进机截割煤壁时所诱发的震动作为被动地震震源,随着迎头的推进,迁移监测台站,达到对工作面前方100 m范围的实时监测,实现对掘进前方内部静态地质异常体的精细探测以及突出危险区等动态灾变条件的监测预警。通过钻探及后期巷道实际揭露资料,验证了该方法的有效性,该方法能提前为井下工作面掘进透明地质探查提供可靠依据,为安全施工提供有力保障,对矿井巷道超前探测具有一定的推广意义。