3D geological modeling for mineral resource assessment of the Tongshan Cu deposit,Heilongjiang Province,China

Three-dimensional geological modeling （3DGM） assists geologists to quantitatively study in three-dimensional （3D） space structures that define temporal and spatial relationships between geological objects. The 3D property model can also be used to infer or deduce causes of geological objects. 3DGM technology provides technical support for extraction of diverse geoscience information, 3D modeling, and quantitative calculation of mineral resources. Based on metallogenic concepts and an ore deposit model, 3DGM technology is applied to analyze geological characteristics of the Tongshan Cu deposit in order to define a metallogenic model and develop a virtual borehole technology; a BP neural network and a 3D interpolation technique were combined to integrate multiple geoscience information in a 3D environment. The results indicate： （1） on basis of the concept of magmatic-hydrothermal Cu polymetallic mineraliza- tion and a porphyry Cu deposit model, a spatial relational database of multiple geoscience information for mineralization in the study area （geology, geophysics, geochemistry, borehole, and cross-section data） was established, and 3D metallogenic geological objects including mineralization stratum, granodiorite, alteration rock, and magnetic anomaly were constructed; （2） on basis of the 3D ore deposit model, 23,800 effective surveys from 94 boreholes and 21 sections were applied to establish 3D orebody models with a kriging interpolation method; （3） combined 23,800 surveys involving 21 sections, using VC＋＋ and OpenGL platform, virtual borehole and virtual section with BP network, and an improved inverse distance interpolation （IDW） method were used to predict and delineate mineralization potential targets （Cu-grade of cell not less than 0.1%）; （4） comparison of 3D ore bodies, metallogenic geological objects of mineralization, and potential targets of mineralization models in the study area, delineated the 3D spatial and temporal relationship and causal processes among the ore bodies, alteration rock, metallo- genic stratum, intrusive rock, and the Tongshan Fault. This study provides important technical support and a scientific basis for assessment of the Tongshan Cu deposit and surrounding exploration and mineral resources.

基于钻孔数据的三维地质建模及可视化系统3DGMS的设计与实现

矿山三维地质建模及可视化是实施数字矿山战略的关键技术,其软件系统的研究与实现对于矿山企业的可持续发展具有极其重要的意义.基于OpenGL图形库和VC++6.0开发平台,从系统目标要求、体系结构和功能模块等几方面设计和开发了基于钻孔数据的三维地质建模及可视化系统3DGMS,实现了地层、矿体、断层、地表和巷道等三维模型的创建与可视化显示,以及灵活的三维视图控制和针对地质模型基本的空间查询、量算、空间剖切、动态模拟等空间分析功能,为我国矿山三维地质建模及可视化软件的设计提供了参考,有益于促进我国矿山信息化的建设.

From the Area to the Point-Study on the Key Technology of 3D Geological Hazard Modeling in Three Gorges Reservoir Area

Taking hundreds of pieces of hazardous geological maps （1 ： 10 000） of Three Gorges res-ervoir area （3GR） as background, we establish regional three-dimensional （3D） geo-hazard modelusing DEM （digital elevation model） superposed surface images and geo-hazards elements. Based on landslides and other geo-hazard survey data,using improved B-REP（boundary representa-tion）entity data structure （two-body 3D data structure）, we set up 3D solid models for each hazardous bodies in each hazardous geological maps. Then we integrate the two types of 3D models with different scales from area to point, which are the regional geo-hazard 3D model and the solid models of each disaster body, in order to provide a visual processing and analysis plat-form for danger partition, stability evaluation, disaster prevention and control, early warning and command.

Evaluation of earthquake impact on magnitude of the minimum principal stress along a shotcrete lined pressure tunnel in Nepal

In situ stress condition in rock mass is influenced by both tectonic activity and geological environment such as faulting and shearing in the rock mass.This influence is of significance in the Himalayan region,where the tectonic movement is active,resulting in periodic dynamic earthquakes.Each large-scale earthquake causes both accumulation and sudden release of strain energy,instigating changes in the in situ stress environment in the rock mass.This paper first highlights the importance of the magnitude of the minimum principal stress in the design of unlined or shotcrete lined pressure tunnel as water conveyance system used for hydropower schemes.Then we evaluated the influence of local shear faults on the magnitude of the minimum principal stress along the shotcrete lined high pressure tunnel of Upper Tamakoshi Hydroelectric Project(UTHP)in Nepal.A detailed assessment of the in situ stress state is carried out using both measured data and three-dimensional(3D)numerical analyses with FLAC3D.Finally,analysis is carried out on the possible changes in the magnitude of the minimum principal stress in the rock mass caused by seismic movement(dynamic loading).A permanent change in the stress state at and nearby the area of shear zones along the tunnel alignment is found to be an eminent process.