Formation mechanism and height calculation of the caved zone and water-conducting fracture zone in solid backfill mining

To study the heights of the caved zone and water-conducting fracture zone in backfill mining,the failure mechanism of strata during backfill mining was analyzed,and a method for determining the heights of the two zones was proposed based on key strata theory.The movement and failure regularity of the strata above the backfilling panel were revealed through numerical simulation.Considering the geologic conditions of the CT101 backfilling panel,the height of the fracture zone was determined using the proposed method along with empirical calculation,numerical simulation,and borehole detection.The results of the new calculation method were similar to in situ measurements.The traditional empirical formula,which is based on the equivalent mining height model,resulted in large errors during calculation.The findings indicate the reliability of the new method and demonstrate its significance for creating reference data for related studies.

Effects of caving–mining ratio on the coal and waste rocks gangue flows and the amount of cyclically caved coal in fully mechanized mining of super-thick coal seams

Aimed at determining the appropriate caving–mining ratio for fully mechanized mining of 20 m thick coal seam, this research investigated the effects of caving–mining ratio on the flow fields of coal and waste rocks, amount of cyclically caved coal and top coal loss by means of numerical modeling. The research was based on the geological conditions of panel 8102 in Tashan coal mine. The results indicated the loose coal and waste rocks formed an elliptical zone around the drawpoint. The ellipse enlarged with decreasing caving–mining ratio. And its long axis inclined to the gob gradually became vertical and facilitating the caving and recovery of top coal. The top coal loss showed a cyclical variation; and the loss cycle was shortened with the decreasing in caving–mining ratio. Moreover, the mean squared error(MSE) of the amount of cyclically caved coal went up with increasing caving–mining ratio, indicating a growing imbalance of amount of cyclically caved coal, which could impede the coordinated mining and caving operations. Finally it was found that a caving–mining ratio of 1:2.51 should be reasonable for the conditions.

A comprehensive review of lunar lava tube base construction and field research on a potential Earth test site

The Moon,as the closest celestial body to the Earth,plays a pivotal role in the progression of deep space exploration,and the establishment of research outposts on its surface represents a crucial step in this mission.Lunar lava tubes are special underground caves formed by volcanic eruptions and are considered as ideal natural shelters and scientific laboratories for lunar base construction.This paper begins with an in-depth overview of the geological origins,exploration history,and distribution locations of lunar lava tubes.Subsequently,it delves into the presentation of four distinctive advantages and typical concepts for constructing bases within lava tubes,summarizing the ground-based attempts made thus far in lunar lava tube base construction.Field studies conducted on a lava tube in Hainan revealed rock compositions similar to those found during the Apollo missions and clear lava tube structures,making it a promising analog site.Lastly,the challenges and opportunities encountered in the field of geotechnical engineering regarding the establishment of lunar lava tube bases are discussed,encompassing cave exploration technologies,in-situ testing methods,geomechanical properties under lunar extreme environments,base design and structural stability assessment,excavation and reinforcement techniques,and simulated Earth-based lava tube base.

Stability analysis of longwall top-coal caving face in extra-thick coal seams based on an innovative numerical hydraulic support model

The relationship between support and surrounding rock is of great significance to the control of surrounding rock in mining process.In view of the fact that most of the existing numerical simulation methods construct virtual elements and stress servo control to approximately replace the hydraulic support problem,this paper establishes a new numerical model of hydraulic support with the same working characteristics as the actual hydraulic support by integrating numerical simulation software Rhino,Griddle and FLAC3D,which can realize the simulation of different working conditions.Based on this model,the influence mechanism of the supporting strength of hydraulic support on surrounding rock stress regulation and coal stability in front of the top coal caving face in extra thick coal seam were researched.Firstly,under different support intensity,the abutment pressure of the bearing coal and the coal in front of it presents the “three-stage”evolution characteristics.The influence range of support intensity is 15%–30%.Secondly,1.5 MPa is the upper limit of impact that the support strength can have on the front coal failure area.Thirdly,within a displacement range of 2.76 m from the coal wall,a support strength of1.5 MPa provides optimal control of the horizontal displacement of the coal.

Seismic identification and characterization of complex storage space oil and gas reservoirs

To predict complex reservoir spaces(with developed caves,pores,and fractures),based on the results of full-azimuth depth migration processing,we adopted reverse weighted nonlinear inversion to improve the accuracy of porous reservoir prediction.Scattering imaging three-parameter wavelet transform technology was used to accurately predict small-scale cave bodies.The joint inversion method of velocity and amplitude anisotropy was developed to improve the accuracy of small and medium-sized fracture prediction.The results of multiscale fracture modeling and characterization,interwell connectivity analysis,and connection path prediction are consistent with the production condition.Finally,based on the above prediction findings,favorable reservoir development areas were predicted.The above ideas and strategies have great application value for the efficient exploration and development of complex storage space reservoirs and the optimization of high-yield well locations.

Control effect and optimization scheme of combined rockboltecable support for a tunnel in horizontally layered limestone:A case study

This study focused on the mechanical behavior of a deep-buried tunnel constructed in horizontally layered limestone,and investigated the effect of a new combined rockboltecable support system on the tunnel response.The Yujingshan Tunnel,excavated through a giant karst cave,was used as a case study.Firstly,a multi-objective optimization model for the rockboltecable support was proposed by using fuzzy mathematics and multi-objective comprehensive decision-making principles.Subsequently,the parameters of the surrounding rock were calibrated by comparing the simulation results obtained by the discrete element method(DEM)with the field monitoring data to obtain an optimized support scheme based on the optimization model.Finally,the optimization scheme was applied to the karst cave section,which was divided into the B-and C-shaped sections.The distribution range of the rockboltecable support in the C-shaped section was larger than that in the B-shaped section.The field monitoring results,including tunnel crown settlement,horizontal convergence,and axial force of the rockboltecable system,were analyzed to assess the effectiveness of the optimization scheme.The maximum crown settlement and horizontal convergence were measured to be 25.9 mm and 35 mm,accounting for 0.1%and 0.2%of the tunnel height and span,respectively.Although the C-shaped section had poorer rock properties than the B-shaped section,the crown settlement and horizontal convergence in the C-shaped section ranged from 46%to 97%of those observed in the B-shaped section.The cable axial force in the Bshaped section was approximately 60%of that in the C-shaped section.The axial force in the crown rockbolt was much smaller than that in the sidewall rockbolt.Field monitoring results demonstrated that the optimized scheme effectively controlled the deformation of the layered surrounding rock,ensuring that it remained within a safe range.These results provide valuable references for the design of support systems in deep-buried tunnels situated in layered rock masses.

Geometry and 3D seismic characterisation of post-rift normal faults in the Pearl River Mouth Basin,northern South China Sea

Based on high-resolution 3D seismic data acquired in the Pearl(Zhujiang)River Mouth Basin of the northern South China Sea,this study investigated the geometry,spatial extension,and throw distribution of the post-rift normal fault through detailed seismic interpretation and fault modeling.A total of 289 post-rift normal faults were identified in the study area and can be classified into four types:(1)isolated normal faults above the carbonate platform;(2)isolated normal faults cutting through the carbonate platform;(3)conjugate normal faults,and(4)connecting normal faults.Throw distribution analysis on the fault planes show that the vertical throw profiles of most normal fault exhibit flat-topped profiles.Isolated normal faults above the carbonate platform exhibit roughly concentric ellipses with maximum throw zones in the central section whereas the normal faults cutting through the carbonate platform miss the lowermost section due to the chaotic seismic reflections in the interior of the carbonate platform.The vertical throws of conjugate normal faults anomalously decrease toward their intersection region on the fault plane whereas the connecting normal faults present two maximum throw zones in the central section of the fault plane.According to the symmetric elliptical distribution model of fault throw,an estimation was made indicating that normal faults cutting through the carbonate platform extended downward between-1308 s and-1780 s(two-way travel time)in depth and may not penetrate the entire Liuhua carbonate platform.Moreover,it is observed that the distribution of karst caves on the top of the carbonate platform disaccord with those of hydrocarbon reservoirs and the post-rift normal faults cutting through the carbonate platform in the study area.We propose that these karst caves formed most probably by corrosive fluids derived from magmatic activities during the Dongsha event,rather than pore waters or hydrocarbons.

Numerical and theoretical study of large-scale failure of strata overlying sublevel caving mines with steeply dipping discontinuities

The deformation and fracture evolution mechanisms of the strata overlying mines mined using sublevel caving were studied via numerical simulations.Moreover,an expression for the normal force acting on the side face of a steeply dipping superimposed cantilever beam in the surrounding rock was deduced based on limit equilibrium theory.The results show the following:(1)surface displacement above metal mines with steeply dipping discontinuities shows significant step characteristics,and(2)the behavior of the strata as they fail exhibits superimposition characteristics.Generally,failure first occurs in certain superimposed strata slightly far from the goaf.Subsequently,with the constant downward excavation of the orebody,the superimposed strata become damaged both upwards away from and downwards toward the goaf.This process continues until the deep part of the steeply dipping superimposed strata forms a large-scale deep fracture plane that connects with the goaf.The deep fracture plane generally makes an angle of 12°-20°with the normal to the steeply dipping discontinuities.The effect of the constant outward transfer of strata movement due to the constant outward failure of the superimposed strata in the metal mines with steeply dipping discontinuities causes the scope of the strata movement in these mines to be larger than expected.The strata in the metal mines with steeply dipping discontinuities mainly show flexural toppling failure.However,the steeply dipping structural strata near the goaf mainly exhibit shear slipping failure,in which case the mechanical model used to describe them can be simplified by treating them as steeply dipping superimposed cantilever beams.By taking the steeply dipping superimposed cantilever beam that first experiences failure as the key stratum,the failure scope of the strata(and criteria for the stability of metal mines with steeply dipping discontinuities mined using sublevel caving)can be obtained via iterative computations from the key stratum,moving downward toward and upwards away from the goaf.

LED-CAVE沉浸式虚拟现实技术在建筑EPC项目中的应用

研究一种基于LED-CAVE的沉浸式虚拟现实技术,结合建筑信息模型(BIM)技术,通过建(构)筑物及其环境的三维BIM模型与五面LED-CAVE显示系统进行整合,实现多人沉浸式的场景漫游功能。通过人机交互逻辑的开发与外部系统集成,应用于建筑EPC项目的设计、采购、施工等各个领域,可以实现方案设计的沉浸式体验与交流,真正实现所见即所得,提升方案设计的效率,加快方案设计的决策,为旧街区的改造提升方案设计提供有效的辅助和指导作用。

CAVE空间中裸眼VR观影技术研究与系统实现

VR电影通常需借助设备呈现于观众的视野中。本文对VR技术当前发展情况及技术局限性进行了研究,并对洞穴式自动虚拟环境(CAVE)空间的原理、优势和应用现状进行了研究,提出并实现了基于CAVE空间的裸眼VR观影体验方案,并可在后期制作中自定义与现实空间同步的最佳观赏点。在电影科技创新需求和观众审美需求日益增长的当下,CAVE空间中的裸眼VR观影具有广阔的应用前景。

Urban Spatial Form Optimization Strategies Based on the Principle of Climate Adaptability of Regional Architecture: A Case Study of Traditional Cave Dwelling Villages in Northern Shaanxi Province

A multitude of climate-adaptive design approaches are embedded in regional architecture,which have a positive impact on addressing the deformed development of urban spatial patterns and the dual challenges of climate and resources.This paper examines the principles of climate adaptability embedded in the site layout and spatial organization characteristics of traditional cave dwelling villages in northern Shaanxi Province.The extracted climate adaptability principles are summarized,and the resulting design strategies that are well-suited to the contemporary urban space form are presented.Through analysis,it can be observed that traditional cave dwelling villages in northern Shaanxi are predominantly situated on south-facing slopes in proximity to water at low altitudes.These villages are characterized by compact building groups and east-west development,which is constrained by the elements of mountains and rivers.A two-level street system is generated,comprising streets parallel to the contour line and roadways perpendicular to the contour line.This results in the formation of a courtyard form enclosed by mountains.Such site layout and spatial organization exhibit excellent climate adaptability with regard to heat,ventilation,and wind storage.In light of the aforementioned considerations,the following urban spatial form design strategies are put forth:①the topographic height difference can be exploited to obtain sufficient sunshine;②the group shape can be optimized in order to reduce building energy consumption;③the best orientation of the building can be chosen to take account of both winter and summer conditions;④the height and length can be combined in order to form natural masking;⑤the D/H ratio of streets and roadways should be controlled to achieve a balance between heat gain and cooling of groups;⑥vents should be set appropriately to optimize group ventilation;⑦climate buffers should be established to increase the level of climate response.

沉浸式技术CAVE在宋韵文化及历史复现上的应用

在有关政策引导下,以CAVE(洞穴状自动虚拟环境)为代表的各类沉浸式技术逐渐进入公共文化教育空间,改进原有单一、单向的展陈模式,辅助传统文化和历史复现。以宋韵文化为例,CAVE系统的应用影响了人们对历史及当下的空间感知和文化认同。人们通过集体观看,在熟悉的现代性“酷”的技术视觉与文化中,认识到个体在历史中的血脉延续性,从而获得沉浸式的文化认同,维续了中华民族这一身份的连贯一致。进而,这一共享的文化认同通过创意产业带动经济发展,将文化价值转化为经济价值。

Analysis of the Application of Span-Bridge Technology for Building Highway Tunnels that Go Over Solutional Caves

This article presents a real engineering project showcasing the application of span-bridge construction technology for building a highway that goes over a solutional cave.An overview of the project and the details of applying this technology in highway construction are provided.Besides,strategies for enhancing its construction quality are also proposed.The objective of this analysis is to improve the safety and quality of similar projects.

初探光学空间定位虚实交互表演环境系统的设计

针对演艺领域提出一种基于光学空间定位虚实交互表演环境系统的实施方案,解析了设计思路、系统架构、技术路线,并针对实施难点提出了解决方案。

Effect of induction unloading on weakening of rock mechanics properties

The effects of induction unloading such as drilling, blasting, lancing and water-infusion softening on weakening of rock mechanics properties were investigated. Three stress paths were chosen as test schemes corresponding to the triaxial compressive test, pre-peak and post-peak unloading the confining pressure tests. The results show that compression deformation is the main cause of rock failure under loading condition. However, the strong dilatation leads to the rock failure along unloading direction. Rock failure happens even under little axial stress with confining pressure unloading. Poisson ratio increases with the decrease of confining pressure during the process of unloading. Elastic modulus increases slowly along with the decline of confining pressure, but decreases rapidly when unloaded to yielding strength. It shows that the weakening rate of rock intensity tends to be faster with easily failure under the unloading condition.

PCCAVE:基于连网PC的廉价CAVE系统

讨论了一个基于 PC的廉价 CAVE系统的实现方法 .FCCAVE使用 4台微机配合中低档的图形显示卡构成图形绘制系统 ,代替 SGI工作站和 Reality Engine高档工作站图形卡 .PCCAVE整体上是一个主从式并行计算结构 ,主节点提供人机交互控制接口 ,从节点接受主节点命令和绘制立体图像 .PCCAVE的通信子系统使用 MPI实现 ,实现了并行计算的同步控制和智能信息代理服务 ,图形子系统以 Direct X和 Open GL 作为底层图形 API.还研究了系统的主要瓶颈和性能指标 .利用该系统实现了浙江大学的校园漫游 .结果表明该系统的许多指标都超越或者接近于 SGI Onyx2 ,具有良好的推广前景和较高的实用价值 .

一种基于CAVE的交互式全景视频显示方法

为了实现全景视频的沉浸式显示,开发了一个基于CAVE的交互式全景视频显示系统.本系统成功地实现了pgr全景视频文件在CAVE上的播放.首先,将全景视频中的每一帧全景图像映射到一个虚拟球面上;其次,使用五个虚拟相机对该球面的四面及顶面进行拍摄,调整各相机的参数使所得各幅图像覆盖整个球面区域,并能够无缝拼接;最后,将所得五幅图像分别投影到CAVE系统中各投影幕中;另外,实现通过鼠标、手柄等输入设备调整CAVE中各投影幕的画面.

CAVE立体显示系统的搭建及立体图像的几何校正

为了解决由投影机的位置不准确而引起的立体图像视差畸变问题,根据立体图像产生方式以及显示方式的不同,给出了适合于工程上搭建"经济型"CAVE立体显示系统的几种实现方式,包括主动立体方式、主动变被动方式以及直接被动立体方式.将帧缓存中双眼的视景图像分别拷贝到纹理内存中,通过重投影变换计算出B样条曲面控制点坐标并绘制B样条曲面,分别映射纹理内存中双眼图像的纹理到各自的B样条曲面上.通过对左右眼立体图像分别进行几何校正,实现了CAVE多通道立体显示的无缝拼接;通过微调B样条曲面的控制点坐标以及确定曲面阶数,实现了左右立体图像局部位置的调整以及图像平滑度的调整.实验结果显示,该方法不影响视景实时绘制.

基于虚拟现实技术的测量数据可视化方法

在从数据可视化的角度对测量数据进行分类的基础上，对两种重要类型的测量数据给出了三维建模方法。然后利用 CAVE 技术和3D 技术，结合以映射、绘制为主线的数据可视化基本流程，提出了一种具有沉浸感和立体感的通用型测量数据可视化方案。技术方案以建立三维模型为基础，以对视图的控制为核心，以场景设置为辅助，实现并验证了测量数据可视化。

基于CAVE的集装箱装卸仿真系统

介绍了基于CAVE系统的集装箱装卸模拟器的硬件平台,给出了本实验室已搭建的CAVE系统的详细配置。阐述了多通道立体显示技术在集装箱装卸模拟器视景系统中的应用,分析了基于被动立体显示的集装箱模拟器的系统构成。通过船舶的压载水调节系统,建立了集装箱装卸操作人员与船舶驾驶员的联系。最后根据拉格朗日运动方程建立了系统的广义坐标下四自由度的运动模型。