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Scale-space effect and scale hybridization in image intelligent recognition of geological discontinuities on rock slopes

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第4期16卷 1315-1336页

作者： Mingyang wang enzhi wang Xiaoli Liu Congcong wang State Key Laboratory of Hydro-science and Engineering Tsinghua UniversityBeijing100084China

Geological discontinuity(GD)plays a pivotal role in determining the catastrophic mechanical failure of jointed rock *** and efficient acquisition of GD networks is essential for characterizing and understanding the progressive damage mechanisms of slopes based on monitoring image *** by recent advances in computer vision,deep learning(DL)models have been widely utilized for image-based fracture *** multi-scale characteristics,image resolution and annotation quality of images will cause a scale-space effect(SSE)that makes features indistinguishable from noise,directly affecting the ***,this effect has not received adequate ***,we try to address this gap by collecting slope images at various proportional scales and constructing multi-scale datasets using image processing ***,we quantify the intensity of feature signals using metrics such as peak signal-to-noise ratio(PSNR)and structural similarity(SSIM).Combining these metrics with the scale-space theory,we investigate the influence of the SSE on the differentiation of multi-scale features and the accuracy of *** is found that augmenting the image's detail capacity does not always yield benefits for vision-based recognition *** light of these observations,we propose a scale hybridization approach based on the diffusion mechanism of scale-space *** results show that scale hybridization strengthens the tolerance of multi-scale feature recognition under complex environmental noise interference and significantly enhances the recognition accuracy of *** also facilitates the objective understanding,description and analysis of the rock behavior and stability of slopes from the perspective of image data.

关键词： Image processing Geological discontinuities Deep learning Multi-scale Scale-space theory Scale hybridization

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Three-dimensional hydro-mechanical coupling numerical simulation of shield-driven cross-river twin tunnels:A case study

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Underground Space 2024年第3期16卷 106-125页

作者： Chengwen wang Xiaoli Liu Danqing Song enzhi wang Guohui Yan Ran Zhou Department of Hydraulic Engineering State Key Laboratory of Hydroscience and EngineeringTsinghua UniversityBeijing 100084China YSD Rail Transit Construction Company Limited Guangzhou 510630China

With the rapid development of urban underground space,the construction of shield-driven cross-river twin tunnels is increasing,and the complex hydro-mechanical coupling effects and twin-tunnel interactions bring huge construction risks to such projects,which have attracted more and more *** study aims to understand the excavation effects induced by shield driving of cross-river twin tunnels through numerical simulation.A refined three-dimensional numerical model based on the fully coupled hydro-mechanical theory is *** model considers the main components of the slurry pressure balance shield(SPBS)machine,including support force,jacking thrust,grouting pressure,shield-rock interaction and lining-grouting interaction,as well as the detailed construction *** purpose is to examine the excavation effects during construction,including rock deformation around tunnels,the change in pore pressure,and the response of the *** results show the influence range of twin-tunnel excavation on rock deformation and pore pressure,as well as the modes of lining *** addition,this study also systematically investigates the effects of water level fluctuation and burial depth on twin-tunnel *** results indicate that the increase of water level or burial depth will enhance the excavation effects and strengthen the twin-tunnel *** results provide useful insights for estimating the construction impact range and degree of twin tunnels,and serve as basic references for the design of cross-river twin tunnels.

关键词： Numerical modeling Twin tunnels Crossing river Hydro-mechanical coupling Lining response

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Effect of confining pressure on rock breaking by high-pressure waterjet-assisted TBM

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Underground Space 2024年第5期18卷 151-161页

作者： Chen Xu Yujie Zhu Xiaoli Liu Fei Chen Min Zhu enzhi wang Sijing wang School of Resource and Environment Engineering Wuhan University of TechnologyWuhan 430070China Changjiang Institute of Survey PlanningDesign and ResearchWuhan 430010China State Key Laboratory of Hydroscience and Engineering Tsinghua UniversityBeijing 100084China Key Laboratory of Geotechnical Mechanics and Engineering of Ministry of Water Resources Wuhan 430010China

High-pressure waterjet-assisted tunnel boring machine(WTBM)is an efficient method for improving the tunneling performance of a tunnel boring machine(TBM)and reducing the wear of its disc cutters in hard rock with high *** pressure directly affects the efficiency of rock breaking and the configuration of the disc *** this study,we evaluated the effect of confining pressure on WTBM rock breaking by developing a self-designed and manufactured experimental system,including confining pressure loading,TBM disc-cutter penetration,and high-pressure *** macro fracture,acoustic emission(AE),peak normal force drop,and specific energy(SE)were analyzed for four different confining pressures(10,20,30,and 35 MPa).The results showed that the cutting depth of the waterjet increased linearly as the waterjet pressure increased and decreased with the gradual increase in the nozzle moving *** expansion and development of cracks formed rock debris,and the size of the rock fragments decreased with an increase in confining *** the waterjet pressure was 280 MPa,the nozzle moving velocity was 800 mm/min and the kerf space was 75 mm,which indicated that the confining pressure,which was 23.16 MPa,minimized the cutting SE under this ***,regardless of the confining pressure,the maximum normal force of WTBM was less than that of a TBM,whereas the SE of WTBM was less than that of complete TBM cutting mode(CTCM).The average force drop and average drop rate of SE were approximately 25%,and 80%,*** results of this study can inspire the design and mechanism of a TBM assisted by a high-pressure waterjet.

关键词： Waterjet Tunnel boring machine(TBM) Confining pressure Specific energy Force drop

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Graph theoretical analysis of limestone fracture network damage patterns based on uniaxial compression test

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第9期16卷 3485-3510页

作者： Mingyang wang Congcong wang enzhi wang Xiaoli Liu Xiao Li State Key Laboratory of Hydro-science and Engineering Tsinghua UniversityBeijing100084China Department of Automation Tsinghua UniversityBeijing100084China Beijing Huairou Laboratory Beijing101400China Institute of Geology and Geophysics Chinese Academy of ScienceBeijing100029China

The topological attributes of fracture networks in limestone,subject to intense hydrodynamics and intricate geological discontinuities,substantially influence the mechanical and hydraulic characteristics of the rock *** dynamical evolution of fracture networks under stress is crucial for unveiling the interaction patterns among ***,existing models are undirected graphs focused on stationary topology,which need optimization to depict fractures'dynamic development and rupture *** compensate for the time and destruction terms,we propose the damage network model,which defines the physical interpretation of fractures through the ternary *** focus primarily on the evolution of node types,topological attributes,and motifs of the fracture network in limestone under uniaxial *** expose the varying behavior of the nodes'self-dynamics and neighbors'adjacent dynamics in the fracture *** approach elucidates the impact of micro-crack behaviors on large brittle shear fractures from a topological perspective and further subdivides the progressive failure stage into four distinct phases(isolated crack growth phase,crack splay phase,damage coalescence phase,and mechanical failure phase)based on the significance profile of the *** analysis reveals a positive linear and negative power correlation between fracture network density and branch number to the rock damage resistance,*** damage network model introduces a novel methodology for depicting the interaction of two-dimensional(2D)projected fractures,considering the dynamic spatiotemporal development characteristics and fracture geometric *** helps dynamically characterize properties such as connectivity,permeability,and damage factors while comprehensively assessing damage in rock mass fracture networks.

关键词： Motif Fracture network Topological property Damage resistance Limestone

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Experimental study on formation mechanism of compaction bands in weathered rocks with high porosity

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Science China(Technological Sciences) 2013年第10期56卷 2563-2571页

作者： HAN GuoFeng LIU XiaoLi wang enzhi State Key Laboratory of Hydroscience and Engineering Tsinghua University Institute of Mechanics

Since Mollema and Antonellini observed compaction bands in the field in 1996,different patterns of compaction bands have been found in laboratory *** are some discrepancies between the laboratory experiments and the field observations:compared to the field observation,the stress levels required to induce compaction bands in laboratory experiments are usually higher than the inferred in the field,and the grain crushing are more intense in the laboratory *** this paper,compaction bands were observed at the maximal principal stresses below 8 MPa,which is lower than the stress level inferred in the field,and there was no severe comminution inside the compaction *** results indicate that the porosity and confining pressure have great impacts on the types of localization *** porosity and confining pressure can promote the growth of shear bands and high-angle shear *** porosity and confining pressure can promote the growth of discrete compaction *** porosity and confining pressure are favorable for the growth of hybrid modes involving two of the three,i.e.,discrete compaction band,diffuse compaction band and high-angle shear *** formation of discrete compaction bands is more unstable compared to diffuse compaction *** two types of compaction bands can appear in the same type rocks,and diffuse compaction bands are formed under lower confining pressure compared to discrete compaction *** reduction of permeability was within 2 orders of magnitude in this study,and it is 2 3 orders of magnitude lower than those obtained by other researchers.

关键词： porous rock compaction band permeability evolution

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深部围岩相变理论与分区破裂化现场实测对比

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煤炭学报 2024年第S1期49卷 72-79页

作者：燕发源王恩志刘晓丽戚承志马庆谢维强马前驰清华大学土木水利学院北京建筑大学土木与交通工程学院

高地应力作用下的深部围岩巷道分区破裂化现象，一直是岩土工程领域研究的热点和难点，其产生和发展对深部工程安全造成了很大影响。当材料发生屈服破坏时，能量出现一定耗散，随着耗散的进行，材料结构也产生相应变化形成新的组织结构... 详细信息

高地应力作用下的深部围岩巷道分区破裂化现象，一直是岩土工程领域研究的热点和难点，其产生和发展对深部工程安全造成了很大影响。当材料发生屈服破坏时，能量出现一定耗散，随着耗散的进行，材料结构也产生相应变化形成新的组织结构，该过程类似于协同学上的自组织过程，此时传统弹塑性力学已经不太能发挥作用，需要借助物理学理论；深部巷道围岩在高地应力作用下，当变形超过弹性极限时，也会出现类似于耗散结构现象，围岩结构需要经历自组织过程形成新的耗散结构，此过程和物理学中的渐进相变现象类似；实际上，深部巷道围岩的变形破坏过程是一个固体向流体转换的二级相变过程，即它具有渐进相变特征。首先对现场尺度、实验室尺度以及模拟试验中出现的各种分区破裂化现象进行了比较分析；随后，基于相变理论模型，通过Poincare解析的参数摄动方法对非线性高阶控制方程进行了近似解析，各参数在近似解中的敏感性也得到了分析；最后，将理论模型计算结果和金属矿山金川矿700 m深的水平巷道中监测到的分区破裂化现场实测数据进行对比验证，结果表明理论半解析解的计算结果与实际测量数据高度符合，验证了针对分区破裂化的相变理论模型和计算方法的正确性。

关键词：相变理论深部围岩分区破裂非线性岩石力学

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Multiscale hierarchical analysis of rock mass and prediction of its mechanical and hydraulic properties

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Journal of Rock Mechanics and Geotechnical Engineering 2018年第4期10卷 694-702页

作者： Xiaoli Liu Guofeng Han enzhi wang Sijing wang Kumar Nawnit State Key Laboratory of Hydroscience and Engineering Tsinghua University Institute of Mechanics Chinese Academy of Sciences Institute of Geology and Geophysics Chinese Academy of Sciences

Engineering geological and hydro-geological characteristics of foundation rock and surrounding rock mass are the main factors that affect the stability of underground engineering. This paper presents the concept of multiscale hierarchical digital rock mass models to describe the rock mass, including its structures in different scales and corresponding scale dependence. Four scales including regional scale,engineering scale, laboratory scale and microscale are determined, and the corresponding scaledependent geological structures and their characterization methods are provided. Image analysis and processing method, geostatistics and Monte Carlo simulation technique are used to establish the multiscale hierarchical digital rock mass models, in which the main micro-and macro-structures of rock mass in different geological units and scales are reflected and connected. A computer code is developed for numerically analyzing the strength, fracture behavior and hydraulic conductivity of rock mass using the multiscale hierarchical digital models. Using the models and methods provided in this paper, the geological information of rock mass in different geological units and scales can be considered sufficiently,and the influence of downscale characteristics(such as meso-scale) on the upscale characteristics(such as engineering scale) can be calculated by considering the discrete geological structures in the downscale model as equivalent continuous media in the upscale model. Thus the mechanical and hydraulic properties of rock mass may be evaluated rationally and precisely. The multiscale hierarchical digital rock mass models and the corresponding methods proposed in this paper provide a unified and simple solution for determining the mechanical and hydraulic properties of rock mass in different scales.

关键词： Multiscale hierarchical digital rock mass models Numerical analysis Evaluation of rock mass quality

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Fracture distribution in overburden strata induced by underground mining

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Deep Underground Science and Engineering 2022年第1期1卷 58-64页

作者： Wenli Yao enzhi wang Xiaoli Liu Ran Zhou Department of Hydraulic Engineering State Key Laboratory of Hydroscience and EngineeringTsinghua UniversityBeijingChina Department of Hydraulic Engineering YSD Rail Transit Construction Company LimitedGuangzhouChina

Coal-mining activities give rise to a series of ecological environmental problems,such as ground settlement and groundwater *** fact,they are mainly caused by mining-induced ***,it is necessary to study the mining-induced fracture distribution to identify the behavior of rock mass ***,the fractures in overburden strata cannot be directly measured owing to the special ***,the majority of previous studies are based on experiments or *** this reason,this study first used a discrete element method to simulate the shape of mining-induced fractures in overburden ***,a geophysical tool of transient electromagnetic method(TEM)was used to investigate the mining-induced fracture *** on the low-resistivity anomaly area,the water-rich area in overburden strata was analyzed to be mainly caused by fracture *** the mutual authentication between numerical simulation and TEM results,the mining-induced fractures in overburden strata were *** study can enhance the understanding of mining-induced fracture distribution on the one hand and guarantee the coal mining safety on the other,thus guiding the coordinated development between coal mining and environmental protection.

关键词： groundwater seepage mining-induced fracture numerical simulation rock mass deformation TEM

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Effects of CO2-water interaction with coal on mineral content and pore characteristics

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Journal of Rock Mechanics and Geotechnical Engineering 2020年第2期12卷 326-337页

作者： Qiuhao Du Xiaoli Liu enzhi wang Jianping Zuo Weimin wang Yujie Zhu State Key Laboratory of Hydro-Science and Engineering Tsinghua UniversityBeijing100084China State Key Laboratory of Coal Resources and Safe Mining China University of Mining and TechnologyBeijing100083China

There are a large number of abandoned coalmines in China,and most of them are located around major coal-fired power stations,which are the largest emission sources of carbon dioxide(CO2).Considering the injection of CO2 into abandoned coalmines,which are usually in the flooded condition,it is necessary to investigate the effect of CO2-water-coal interaction on minerals and pore structures at different pressures,temperatures and *** reveals that the CO2-water-coal interaction can significantly improve the solubility of Ca,S,Mg,K,Si,Al,Fe and *** comparing the mineral content and pore structure before and after CO2-water-coal interaction,quartz and kaolinite were found to be the main secondary minerals,which increased in all *** structures of micropores and mesopores in the range of 1.5-8 nm were changed *** surface areas and pore volumes first increased and then decreased with pressure and time,while both increased with *** using the Frenkel-Halsey-Hill model,the fractal dimensions of all samples were analyzed based on D(s1)and D(s2),which reflected the co mplexities of the pore surface and pore volume,*** re sults show that fractal dimensions had very weak positive correlations with the carbon content.D(s1)had a positive correlation with the quartz and kaolinite contents,while D(s2)had a negative correlation with the quartz and kaolinite contents.

关键词： Carbon dioxide(CO2)sequestration Abandoned coalmines Mineral content Pore structure

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Laboratory-scale investigation of response characteristics of liquid-filled rock joints with different joint inclinations under dynamic loading

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第2期14卷 396-406页

作者： Jin Huang Xiaoli Liu Danqing Song Jian Zhao enzhi wang Jianmin Zhang State Key Laboratory of Hydroscience and Engineering Tsinghua UniversityBeijing100084China Department of Civil Engineering Monash UniversityClaytonVIC3800Australia

In underground rock engineering,water-bearing faults may be subjected to dynamic loading,resulting in the coupling of hydraulic and dynamic *** the interaction mechanism between the stress waves induced by dynamic loadings and liquid-filled rock joints is therefore *** this study,an auxiliary device for simulating the liquid-filled layer was developed to analyze the dynamic response characteristics of liquid-filled rock joints in *** and polymethyl methacrylate(PMMA)specimens were chosen for testing,and high-amplitude shock waves induced by a split Hopkinson pressure bar(SHPB)were used to produce dynamic *** loading tests were conducted on liquid-filled rock joints with different joint *** energy propagation coefficient and peak liquid pressure were proposed to investigate the energy propagation and attenuation of waves propagating across the joints,as well as the dynamic response characteristics of the liquid in the liquid-filled rock *** the inclination angle range considered herein,the experimental results showed that the energy propagation coefficient gently diminished with increasing joint inclination,and smaller coefficient values were obtained for granite specimens compared with PMMA *** peak liquid pressure exhibited a gradually decreasing trend with increasing joint inclination,and the peak pressure for granite specimens was slightly higher than that for PMMA ***,this paper may provide a considerably better method for studying liquid-filled rock joints at the laboratory scale,and serves as a guide for interpreting the underlying mechanisms for interactions between stress waves and liquid-filled rock joints.

关键词： Liquid-filled rock joint Stress wave Laboratory investigation Wave propagation characteristics Liquid dynamic response

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