秦岭造山带多金属矿普查复杂地层护壁堵漏技术

秦岭造山带多金属矿普查项目钻探施工过程中钻遇多种复杂地层,垮塌、缩径、漏失等复杂情况频发,严重影响了施工效率。分别采用了植物胶钙处理钻井液、聚乙烯醇无固相钻井液等进行护壁工作,结合不同漏失情况分别实施了随钻堵漏、凝胶堵漏等技术措施,取得了良好的使用效果。     

A Floating Astronomical Time Scale for the Early Late Cretaceous Continental Strata in the Songliao Basin,Northeastern China

A continuous terrestrial succession was recovered from the Songke-2(SK-2) borehole in the Songliao Basin, Northeastern China. This borehole provides a unique material for further research on the continental paleoclimate during Cretaceous greenhouse period, following a series of achievements of the Songke-1(SK-1) core. In this study, thorium(Th) logging data were chosen as a paleoclimate proxy to conduct a detailed cyclostratigraphic analysis. The Th series varies quasi-periodically; power spectra and evolutionary fast Fourier transformation(FFT) analysis reveal significant cycles in the Quantou(K2 q), Qingshankou(K2 qn), Yaojia(K2 y) and Nenjiang(K2 n) formations. The ratio of cycle wavelengths in these stratigraphic units is approximately 20:5:2:1, corresponding to long orbital eccentricity(405 kyr), short orbital eccentricity(100 kyr), obliquity(37 kyr), and precession cycles(22.5 kyr and 18.4 kyr). The durations of the K2 n, K2 y, K2 qn and K2 q are estimated as 6.97, 1.83, 5.30 and 4.52 Myr, respectively, based on the constructed ～18.62 Myr "floating" astronomical time scale(ATS). Comparison of the durations between the SK-1 s and SK-2 boreholes exhibits a slight difference of 0.06 Myr and 0.459 Myr for K2 qn and K2 y. Nevertheless, our ATS of K2 n supports the chronostratigraphic frame constructed by the CA-ID-TIMS data of the SK-1 s borehole. This new "floating" ATS provides precise numerical ages for stratigraphic boundaries, biozones and geological events in the Songliao Basin, and can serve as a basis for correlation of strata and events between marine and terrestrial systems.     

A Review of the Calculation Formula for the Four-component Borehole Strainmeter and Application to Earthquake Cases

Based on the principle formula for the four-component strainmeters, we can directly obtain the specific plane strain, shear strain and azimuthal angle of the principal strain, and the maximum and minimum principal strains calculated afterwards are the indirect result. The problems of practicality of the sensitivity coefficients A and B of plane strain and shear strain are then discussed. Based on this idea, we analyzed the observation data of several four-component borehole strainmeters near the epicenter of the Yiliang M_S5.7 earthquake in 2012 and the Ludian M_S6.5 earthquake in 2014 in the Zhaotong area, Yunnan Province. The results show that the analysis based on the perspective of plane strain and shear strain has an obviously better effect than that based on the component readings, and can directly peel off the respective abnormality of the plane strain and shear strain. In addition, the correlation coefficient curves between measured data of two plane strains show significant anomalies which often occur several days before and during the earthquake.     

利用自洽方程计算法分析天山中段分量钻孔应变资料可靠性

根据天山中段8套四分量钻孔应变仪观测资料,利用自洽方程计算应变观测的信度,用信度指标检验数据的可靠性,从而进一步用自洽方程计算实际各元件灵敏度的相对大小,并用相对标定的结果,对观测数据进行校正。结果表明:①石场、巴仑台、巴音沟、雀儿沟、榆树沟和库米什台经过校正后,数据观测信度有了明显提升,其中石场和雀儿沟台的数据信度最高;②库米什台校正前数据观测信度较高,因个别“坏点”影响,校正后,观测信度反而下降;③小泉沟和新源台数据信度较低,存在从自洽到失洽的情况,分析认为这可能与系统自身存在问题有关,也有可能是前兆异常,有待进一步研究。     

Challenging sub terra nullius: a critical underground urbanism project

ABSTRACT

Underground urban development is rapidly expanding. Like all forms of ‘development’, utilising the underneath of cities can present a range of possibilities and problems. Much underground urban development, however, has been conceptualised through a technical rather than a broader social lens. This is problematic, not least as these developments are usually financed with public money, while their governance is often realised through complicated and opaque public–private partnerships. In this context, the urban underground is often present as sub terra nullius: an epistemologically blank slate waiting to be exploited with the necessary technology and funding. In this paper, the author presents four analytical strata to help us to rethink how urban undergrounds are conceptualised and developed. Drawing on examples from Australia, she presents how we need to appreciate the more-than-human geographies of the underground (stratum 1); critically understand the dynamics of volumetric dispossession (stratum 2); question who owns the underground and how (stratum 3); and rethink how the underground is accessed (stratum 4). By engaging with these themes, we can explore ways to move subterranean urban development away from a technoscientific tunnelling decision-making process to one that engages with the social, political and economic implications of urban infrastructural projects.     

Solutions for the deformations and stability of elastoplastic hollow cylinders subjected to boundary pressures

In this paper, a closed-form solution is presented for the stress and displacement distributions throughout a hollow cylinder subjected to uniform pressures acting on its internal and external boundary surfaces under plane strain conditions. The material is assumed to be elastoplastic, obeying a Mohr–Coulomb failure criterion, and exhibiting dilatant plastic deformation according to a non-associated flow rule. The newly developed analytical solution is verified through comparison with the solutions obtained from an infinite boundary problem (for which a closed-form solution exists), and numerical analyses using the program FLAC. The solution is also compared with the results of a borehole collapse test on a thick-walled hollow cylinder of synthetic shale. The analytical solution can be used to calculate the stress and displacement distributions around boreholes and other cylindrical cavities under both infinite and finite boundary conditions under both drained and undrained conditions. Copyright © 1999 John Wiley & Sons, Ltd.     

测震井下观测压制背景噪声特征分析

利用赤峰台井下和山洞观测、二连浩特台井下和地表观测测震数据,通过计算其加速度PSD值和相应的PDF值及1~20 Hz频段RMS值,研究井下观测压制测震台站背景噪声的特征。结果表明,在大于2 Hz频段,井下观测相比于山洞和地表观测有显著的压制背景噪声特征,尤其在大于9 Hz频段压制背景噪声特征突出;在16 s~2 Hz频段,井下、山洞、地表观测测震台站背景噪声水平一致性较高,井下观测在该频段不能压制背景噪声;在低于16 s频段,井下观测相比于山洞和地表观测有一定的压制背景噪声特征。通过井下观测可有效降低测震台站背景噪声水平,从而提高观测数据质量。     

基于钻孔数据的三维地层建模关键技术

在基于钻孔数据进行三维地层建模方法中,钻孔样本间地层层序不一致导致建模时难以确定各地层的拓扑关系,快速准确地确定各地层层序和充分利用钻孔数据是建模的关键难点之一。拟通过综合考虑区域内所有钻孔数据,基于地质解释方法理论,以地层出现次数频率高原则进行全自动确定地层层序。首次引入子钻孔递归思想,利用表面建模方法,自下而上逐层创建三维地层模型,可确保钻孔数据不丢失且准确地应用于地层建模中,并能适应地层尖灭、地层超覆、透镜体等复杂地质构造。该方法地学意义明确,具有鲁棒性好、运行效率高及可操作性强等特点,算法已在同济曙光软件中实现,并已在多个实际地质建模工程中得到了验证。研究结果表明,该算法能充分利用已有钻孔信息,建模过程全自动完成,对复杂地层建模亦具有较强的适应性。     

RZB钻孔应变仪量程扩展的研究

为使RZB型钻孔应变仪在千米深井水压的作用下能够正常工作,设计了以陶瓷马达为核心、RS485总线为基础的远程控制机构,用以补偿传感元件的初始位移,从而实现RZB型钻孔应变仪量程的扩展,并在实验室开展了10 MPa水压的模拟实验。结果显示,装有量程扩展系统的传感器在5 MPa处超量程,经量程调节后,在10 MPa处仍能正常工作。     

吉林通化地震台四分量钻孔应变在日本9.0级地震前后的变化特征

基于通化地震台四分量应变观测,通过K-L最佳直线拟合及傅立叶滑动去年周期对数据进行处理,进一步分析日本9.0级地震前后应变变化特征。结果表明,K-L最佳直线拟合和傅立叶滑动去年周期,可以较好地消除通化台应变观测中的长趋势变化项和年变成分,使应力应变的微动态变化更加显著地表现出来;通化台四分量应变在日本9.0级地震前的压性变化与同一构造带的另外两个台站分量应变观测的大幅压性变化一致;日本9.0级地震使通化台面应变出现持续约8个月左右的扩张变化,变化性质与由GPS计算得到的同震位移结果较为一致。