智利赛罗卢娜铁多金属矿区高精度磁测异常特征及找矿预测

测区位于智利海岸山带铁氧化物铜金成矿带、阿塔卡玛断裂系统上。该地区地表覆盖厚,残坡积沙土及碎石层发育。为了有效提高地质找矿成果,采用地面高精度磁测与地质联合检查异常的找矿方法,通过对磁异常特征的综合分析和钻探对异常进行验证,在磁异常区发现了磁铁矿,进一步圈定出找矿有利地段,取得了良好的找矿效果。     

金属矿深部采场结构参数的模糊层次分析综合评判优化

根据内蒙古柴胡栏子金矿实际开采情况,采用三因素三水平正交试验法对采场结构参数进行优化,并结合三维有限元数值计算获取各因素的评判指标值.采用模糊数学理论和层次分析法建立目标相对优属度矩阵和权重矩阵,最后综合评判选出适宜方案.结果表明,柴胡栏子金矿深部开采的适宜采场结构参数为:采场长度40 m,间柱宽度10 m,顶柱厚度5...     

不同接地装置类型下接地电阻测量研究

接地电阻的测量对电力系统供电质量起着至关重要的作用.传统的三极直线法受电磁感应、土壤电阻率不均匀的影响,测量误差较大.通过理论计算分析得出:对于中小型接地装置,采用等边三角形法测量接地电阻;对于大型接地装置,测试电气完整性来保证接地电阻满足设计要求.该测量方法可推广应用于所有的接地电阻测试.     

大跨度分岔隧道施工优化与地表沉降控制

为了探寻到能确保大跨度分岔隧道施工过程中使地表沉降控制在所要求的范围内的最优施工方案,首先采用数值模拟方法,对6种工法进行优化比选,初步确定工法1为最优工法,并在此基础上,对引起地表沉降变形显著增大的汇合段的开挖进行了进一步优化,提出了4步工法、5步工法、6步工法、7步工法和8步工法等5种方案,分析了因施工工序的不同而引起的地表沉降变形的规律,提出了8步工法为最优的方案,并对引起地表沉降突变的关键工序采取了相应的技术对策。     

Predicting geological hazards during tunnel construction

The complicated geological conditions and geological hazards are challenging problems during tunnel construction,which will cause great losses of life and property.Therefore,reliable prediction of geological defective features,such as faults,karst caves and groundwater,has important practical significances and theoretical values.In this paper,we presented the criteria for detecting typical geological anomalies using the tunnel seismic prediction（TSP） method.The ground penetrating radar（GPR） signal response to water-bearing structures was used for theoretical derivations.And the 3D tomography of the transient electromagnetic method（TEM） was used to develop an equivalent conductance method.Based on the improvement of a single prediction technique,we developed a technical system for reliable prediction of geological defective features by analyzing the advantages and disadvantages of all prediction methods.The procedure of the application of this system was introduced in detail.For prediction,the selection of prediction methods is an important and challenging work.The analytic hierarchy process（AHP） was developed for prediction optimization.We applied the newly developed prediction system to several important projects in China,including Hurongxi highway,Jinping II hydropower station,and Kiaochow Bay subsea tunnel.The case studies show that the geological defective features can be successfully detected with good precision and efficiency,and the prediction system is proved to be an effective means to minimize the risks of geological hazards during tunnel construction.     

起始水力梯度对真空预压下砂井地基固结过程的影响

针对粘土中孔隙水渗流存在起始水力梯度的现象,将考虑起始水力梯度的非Darcy渗流方程引入传统的砂井固结理论对其进行修正,并给出了真空预压下砂井地基固结近似解。探讨起始水力梯度对真空预压下砂井地基固结过程的影响,包括渗流前锋面的运动规律、孔隙水压力的分布变化规律和平均固结度的变化规律。结果表明,由于存在起始水力梯度,会延缓真空压力的传播,进而影响孔隙水的渗流和整个土层的固结速度。起始水力梯度越大,滞后现象越明显。此外,起始水力梯度的存在将使平均孔隙水压力逐渐趋于某一稳定值,但无法达到真空压力,所以最终平均固结度将小于100%,且其值随起始水力梯度的增大而减小。     

Research on unloading nonlinear mechanical characteristics of jointed rock masses

Geological environments of rock mass projects are always very complicated, and further investigations on rock mechanical characteristics are needed. There are considerable distinctions in rock mechanical characteristics under unloading and loading conditions. A series of tests are conducted to study the stress-strain relationship of rock masses under loading and unloading conditions. Also, the anisotropy, the size effect, and the rheological property of unloading rock mass are investigated. The tests presented in the paper include model test and granite rheological test, which are conducted considering geological condition, rock mass structure, in-situ stress field of the permanent shiplock of the Three Gorges Project. The main differences between loading and unloading rock masses are stress paths, yield criteria, deformation and strength parameters, etc.. Different structural plane directions affect unloading rock mass evidently. With increasing size, the tensile strength, the compressive strength, the deformation modulus, the Poisson’s ratio and the anisotropy of rock mass all decrease. For sandstone samples with parallel bedding planes, the cohesion c increases but the internal friction angle ? decreases under unloading condition when compared with the values under loading condition. While for samples with vertical bedding planes, the trend is adverse. The rheological property of rocks has close relationship with the tensile stresses of rock masses. When the sandstone samples are tested under high stress condition, their rheological properties are very obvious with the unloading of confining pressure, and three typical rheological stages are shown. Rheological rate changes with the variations in axial stress and confining pressure.     

印制板中地线正确连接原则的讨论

印制板的接地方式非常重要,如果地线布线不合理,就可能引起不可接受的测量误差。本文通过一个典型的热电偶数字测温系统的地线连接的分析,来说明PCB中地线正确连接的重要性和接地原则。文章说明了在模拟和数字信号混合系统中连接PCB地线时,应该防止有较大的地电流,特别是应防止数字电路中大的脉冲地电流流入模拟电路的地线中,尤其不应流入小信号模拟电路的地线中。     

LED电子显示屏系统稳定性的探讨

近年来LED多媒体技术在我国长足发展,应用渐广。而涉足此行业的公司大小、技术水平参差不齐。因此我们重点对LED电子显示屏安装过程中,其系统整体稳定性需要注意哪些事项进行探讨。     

天基地基一体化测控系统研究及应用

未来新武器装备飞行试验向着低空、高速、远程和多目标的方向发展。为满足未来新武器装备飞行试验对测控系统的需求,依据国内外靶场测控和相关技术领域发展现状,提出了基于地基与天基一体化测控网方案,此方案主要是以平流层飞艇作为空中平台,加装小型先进的光测设备、小孔径雷达及遥测转发器等平台设备,通过通信网络传输,实现未来大航区测控和自主机动靶场建设需要。