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Numerical Study of the Failure Process of Stone Column Groups in Soft Soil in Response to Rigid Loading Based on the DEM-FDM Coupled Model

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INTERNATIONAL JOURNAL OF GEOMECHANICS 2025年第4期25卷

作者： Tan, Xin Luo, Mengfei Yin, Xin Hu, Zhengbo Jin, Yuxuan Chen, Changfu Hunan Univ Coll Civil Engn Changsha 410082 Peoples R China Changsha Univ Sci & Technol Sch Traff & Transportat Engn Changsha 410014 Peoples R China Hunan Commun Res Inst Co Ltd Changsha 410029 Peoples R China

Compared with isolated stone columns, a group of stone columns exhibits a much more complicated failure mechanism because of the complicated interactions between the respective columns and the surrounding soil under various loadings, as well as the influence of the relevant geometries. Here, a numerical study based on the discrete-element method and finite-difference method coupled model was conducted to simulate the complete load-bearing process of stone column groups and to better understand the deformation and failure mechanisms of stone column groups in soft soil in response to rigid loading. The load settlement curves for the columns, soil, and loading plate were determined as the displacement and stress evolution. Moreover, the shear strain distribution indicating the ground failure mode during the complete loading process was visualized. Parametric studies considered the influences of the column arrangement, the soil strength, and various stiffnesses. The bearing capacity of individual columns within a stone column group varies due to the differing stress states of the surrounding soil. Edge columns typically fail first, thus transferring load to the internal columns. With a smaller number of columns, transferred loads can trigger internal column failures, resulting in overall instability of the column group. The strength and stiffness of the surrounding soil govern the stone column-bearing capacity. However, existing bearing capacity formulas primarily rely on soil strength parameters, ignoring the significance of soil stiffness.

关键词： Stone column Group column Numerical simulation Failure Interaction Discrete-element method universal distinct element code

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Prediction of seepage water pressure for slope stability at the Gol-E-Gohar open pit mine

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JOURNAL OF MINING SCIENCE 2016年第6期52卷 1069-1079页

作者： Moosavi, E. Shirinabadi, R. Gholinejad, M. Islamic Azad Univ South Tehran Branch Dept Min Engn Tehran Iran

Slope stability accidents are one of the leading causes of destruction at open pit mining operations. Such interception of the seepage water results in the water inflow from the surrounding aquifer towards the mine excavations. In order to design an effective drainage scheme for an open pit mine, prediction of water inflow into the pit is essential. These changes have resulted in some failures and instability problems in different parts of Gol-E-Gohar iron open pit mine. It seems that main parameters which effect the failure and instability of the mine slopes are high pressure of groundwater and system of discontinuities (faults, joins, and bedding planes), which intersect the pit walls. The analysis results indicate that stability of the final pit slopes is sensitive to multi-planar failures and confined water in the walls pit is also a factor adversely affecting the stability. Problems associated with groundwater at the site were also assessed with the analyses of piezometric level and groundwater inflow.

关键词： Seepage water pressure slope stability universal distinct element code Gol-E-Gohar open pit mine

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Simulating Hydraulic Fracture Re-orientation in Heterogeneous Rocks with an Improved Discrete element Method

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ROCK MECHANICS AND ROCK ENGINEERING 2021年第6期54卷 2859-2879页

作者： He, Qingyuan Zhu, Lei Li, Yingchun Li, Danqi Zhang, Boyang China Univ Min & Technol Sch Mines State Key Lab Coal Resources & Safe Min Xuzhou 221116 Jiangsu Peoples R China Dalian Univ Technol State Key Lab Coastal & Offshore Engn Dalian 116024 Peoples R China Curtin Univ WA Sch Mines Minerals Energy & Chem Engn Kalgoorlie WA 6430 Australia Henan Polytech Univ Sch Civil Engn Jiaozuo 454000 Henan Peoples R China

Understanding the hydraulic fracture (HF) re-orientation mechanism from artificial weaknesses is critical to screen-out prevention in the petroleum industry and caveability management in the mining industry. An improved discrete element method is proposed and incorporated in the universal distinct element code (UDEC) to simulate hydraulic fracturing in heterogeneous rocks, and its reliability is validated against previous laboratory experiments. The effects of rock heterogeneity and rock strength on HF re-orientation are unveiled to fill the research gaps in the existing knowledge. The results show that the proposed UDEC T-W (Trigon-Weibull distribution) model can well simulate HF propagation in rock samples of different homogeneity degrees and yields more realistic simulation results compared with the classic extended finite element method (XFEM). The HF re-orientation process depends on the combined effect of all the influencing factors. HFs tend to be directed by perforations if hydraulic fracturing is performed in relatively heterogeneous rocks, while the differential stress is more likely to dictate the HF propagation paths if rocks become relatively homogeneous. We also find that higher rock strength weakens the impact of the differential stress and favours the control of perforations over HF propagation. Finally, recommendations are provided for effective utilization of hydraulic fracturing at the mine site.

关键词： Hydraulic fracture re-orientation universal distinct element code Trigon logic Weibull distribution Rock heterogeneity

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Numerical Modeling of Ground Movement due to Twin Tunnel Structure of Esfahan Subway, Iran

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JOURNAL OF MINING SCIENCE 2017年第4期53卷 663-675页

作者： Moosavi, E. Shirinabadi, R. Rahimi, E. Gholinejad, M. Islamic Azad Univ South Tehran Branch Dept Min Engn Tehran Iran

Tunneling operations in urban areas are always associated with surface and subsurface ground movement, which may affect the stability of nearby structures and utilities. One of the main issues in the analysis and design of tunnels, is ground movement after the support systems and settlement systems caused by excavation. This paper takes the discrete element calculation software of universal distinct element code (UDEC) to set three dimensional calculations models to simulate the construction of Esfahan subway tunnel, analyzing the displacement and stress dynamic response during the construction process. The paper also carries out the comparison analysis of the field measurement of the ground movement. The result indicates that the simulation objectively reflected the rules of movement during the construction process. The results show that the tunnels are stable before support system installation and the tunnel induced movement is allowable.

关键词： Ground movement universal distinct element code simulation twin tunnel of Esfahan subway

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Modelling failure mechanisms to explain rock slope change along the Isle of Purbeck coast, UK

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EARTH SURFACE PROCESSES AND LANDFORMS 1998年第8期23卷 731-750页

作者： Allison, RJ Kimber, OG Univ Durham Dept Geog Sci Labs Durham DH1 3LE England

Results are presented of distinct element computer modelling used to examine rates and mechanisms of change in rock slopes and cliffs, where material intact properties determine process and form but the most significant controls are the joint pattern and cross-joint properties. The modelling approach does not appear to have been used before in a geomorphological context and provides an alternative approach for examining cliff development. Field and laboratory data have been collected for the Portland Limestone outcrop of the Isle of Purbeck, central southern England. The Portland Limestone is a hard, shelly, crystalline sediment of the Upper Jurassic. It has a regular discontinuity pattern throughout the outcrop in Purbeck. While joint orientation remains relatively constant, bedding changes from horizontal to vertical, a consequence of the Purbeck Monocline. There are resulting implications for spatial variations in rock slope evolution. The modelling exercise enhances previous knowledge on rock failure mechanisms and slope development along the Purbeck coast and demonstrates its potential in research where landforms are developed in lithified, jointed rock masses. (C) 1998 John Wiley & Sons, Ltd.

关键词： rock slopes rock mass properties distinct element analysis universal distinct element code Isle of Purbeck, Dorset

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Hydromechanical modeling of a large moving rock slope inferred from slope levelling coupled to spring long-term hydrochemical monitoring: Example of the La Clapie're landslide (Southern Alps, France)

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JOURNAL OF HYDROLOGY 2004年第1-2期291卷 67-90页

作者： Cappa, F Guglielmi, Y Soukatchoff, VM Mudry, J Bertrand, C Charmoille, A UNSA Mecatec Unit UMR 6526 Geosci Azur CNRS F-06560 Valbonne France Ecole Natl Super Mines LAEGO F-54042 Nancy France Univ Franche EA 2642 F-25030 Besancon France

Taking the example of the La Clapiere landslide, the influence of water infiltration on large moving rock mass stability is investigated. Based on the analysis of geological, hydrogeological, hydrogeochemstry and landslide velocity measurements, a hydromechanical conceptual model is proposed. Then, a two-dimensional numerical modeling with the universal distinct element code (UDEC) was carried out to determine the influence of the location and the amount of water infiltration on the hydromechanical behaviour of La Clapiere slope. Geological and hydrogeological analyses indicate a perched water-saturated zone connected by large conducting-flow fractures to a basal aquifer. The comparisons of spring water chemistry data and meteorological data from the slope area show a large variability of groundwater transits in the slope through time (transit durations of 1-21 days) and space. Water infiltration transient signals correspond to accelerations of the slope downward motion. Infiltration rates are comprised between 0.4 and 0.81 s(-1). The most pronounced hydromechanical response of the slope instability is due to snowmelting in the stable area located between elevations 1800 and 2500 m above the unstable slope. The hydromechanical modeling performed with the UDEC code concerns firstly a model of a slope without any unstable zone, and, secondly, a model including a failure surface in order to simulate the current instability. Numerical computations are done in order to localize the area through which water infiltration is the most destabilizing. The most destabilizing area is the one that has the largest influence on the spatial distribution of strain fields. It corresponds to water infiltration located in the middle part of the slope and characterized by weak flow rates of 0.751 s(-1). This approach can easily be applied to the monitoring of other unstable rocky slopes. As it gives relevant information about the spatial and temporal effects of meteoric infiltration, it

关键词： large moving rock mass groundwater chemistry coupled hydromechanical modeling universal distinct element code

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Combination of engineering geological data and numerical modeling results to classify the tunnel route based on the groundwater seepage

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GEOMECHANICS AND ENGINEERING 2017年第4期13卷 671-683页

作者： Aalianvari, A. Univ Kashan Min Engn Dept Fac Engn Kashan Iran

Groundwater control is a significant issue in most underground construction. An estimate of the inflow rate is required to size the pumping system, and treatment plant facilities for construction planning and cost assessment. An estimate of the excavation-induced drawdown of the initial groundwater level is required to evaluate potential environmental impacts. Analytical and empirical methods used in current engineering practice do not adequately account for the effect of the jointed-rock-mass anisotropy and heterogeneity. The impact of geo-structural anisotropy of fractured rocks on tunnel inflows is addressed and the limitations of analytical solutions assuming isotropic hydraulic conductivity are discussed. In this paper the unexcavated Zagros tunnel route has been classified from groundwater flow point of view based on the combination of observed water inflow and numerical modeling results. Results show that, in this hard rock tunnel, flow usually concentrates in some areas, and much of the tunnel is dry. So the remaining unexcavated Zagros tunnel route has been categorized into three categories including high Risk, moderately risk and low risk. Results show that around 60 m of tunnel (3%) length can conduit the large amount of water into tunnel and categorized into high risk zone and about 45% of tunnel route has moderately risk. The reason is that, in this tunnel, most of the water flows in rock fractures and fractures typically occur in a clustered pattern rather than in a regular or random pattern.

关键词： tunnel seepage hazard classification universal distinct element code

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A Simplified Algorithm for Designing Tunnel Composite Support System in Discontinuous Rock Media

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INDIAN GEOTECHNICAL JOURNAL 2020年第3期50卷 442-453页

作者： Farahi, Aref Salari-Rad, Hossein Karimi, Omid Amirkabir Univ Technol Tehran Iran

Since the introduction of the primary support systems in tunnels, many researchers tried to enhance their composite-like behavior by improving the behavior of structural elements. In this study, the behavior of composite lining with three elements (mesh + frame + shotcrete) was investigated based on the share of each structural element from section's internal forces using equations derived from shell theory. Then, the result was compared to results of composite section consisting of two elements (frame + shotcrete) in order to determine the role of mesh in bending and axial capacities of composite section. The results showed that mesh element helps the section's composite-like behavior and increases the bending and axial capacities. Based on this comparison, an algorithm was presented for determining frame spacing as a critical parameter with technical and economical points of view. In this algorithm, an iterative process was introduced to determine lining equivalent section's properties, inputs for universal distinct element numerical model, based on structural elements, frame spacing and structural analysis methods. The outputs of the numerical method (bending moment distribution, axial force and shear force in the equivalent section) were returned to theoretical model and were compared to structural elements' capacity diagrams. This process continued until the internal forces reached the range within that of the capacity diagrams. Results indicate that the addition of mesh element reduces the shotcrete's and steel frame's share of section's internal forces. Thus, the steel frame spacing could be increased and the costs of primary support system per meter could be reduced.

关键词： Composite support system Capacity diagram universal distinct element code Structural analysis Steel frame spacing Discontinuous media

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Mechanisms of failure and slope development in rock masses

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TRANSACTIONS OF THE INSTITUTE OF BRITISH GEOGRAPHERS 1998年第3期23卷 353-370页

作者： Kimber, OG Allison, RJ Cox, NJ Univ Durham Dept Geog Sci Labs Durham DH1 3LE England

This paper examines the mechanisms of failure in jointed rock slopes. The distribution of discontinuities is a significant control of rock-mass stability, determining the mechanism by which blocks fail from a cliff and the consequent slope development through time. It is often assumed that the principles of single-block movements are geomechanically similar to those of larger, multiple-block rock-mass failures, under a given set of boundary conditions and controlling variables. Results presented here, based on computer modelling using the universal distinct element code (UDEC), show that such assumptions are not always correct. After a theoretical modelling exercise, real-world rock slopes were studied from the Portland Limestone outcrop of the Isle of Purbeck, England. There is good association between the theoretical results and model output for the fieldsites. The conclusions are thus useful in enhancing knowledge of jointed rock-mass failure conditions, and improving understanding of rock-slope development.

关键词： slope development computer modelling universal distinct element code rock-failure mechanisms Isle of Purbeck

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Research on dynamic response of rock slope with weak layer

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ROCK AND SOIL MECHANICS 2013年第SUPPL1期34卷 365-+页

作者： Li Peng Su Sheng-rui Wang Yan-chao Wang Qi Changan Univ Coll Geol Engn & Geomat Xian 710054 Shaanxi Peoples R China

Researching on the dynamic response of the rock slopes with weak layer has become an important issue in slope stability analysis. In order to discuss the influences of dynamic response of rock slope by weak layer's characteristics and provide the directions and guidance for slope disaster prevention and mitigation under the dynamic load, the distinct element models are built and dynamic response of rock slopes with weak layer under seismic force are simulated by the universal distict element code(UDEC). After simulating in different conditions: various dip angles, burial depths, elastic moduli, thicknesses, Poisson's ratios and shear stiffness factors of the weak layer, the amplitude values of slope crest and bottom are obtained and the amplification coefficients are calculated;through systematically analyze the amplification coefficients, the amplification law of slope crest which influenced by seismic wave is got, namely, with increasing of dip angle, the amplification coefficient demonstrates increase. decrease. reincrease. decrease law, and appears response weakening phenomenon at the decreased parts. Along with burial depth and thickness increasing of weak layer, the amplification become bigger, but it decreases with elastic modulus and the shear stiffness increasing;the amplification almost doesn't change with increasing of Poisson's ratio. Combining with the non-repetitive test binary analysis of variance evaluation theory, the obtained slope amplification coefficients are analyzed;and then, it is obtained that the significant factors which contribute to the slope dynamic response from great to small are the dip angle, burial depth, elastic modulus, shear stiffness, thickness, Poisson's ratio of the weak layer. The results are helpful to further researches on the slope instability mechanism under earthquake, and can provide the significante guidance to slope disaster prevention in earthquake region.

关键词： universal distinct element code rock slope dynamic response weak layer amplification coefficient

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