三峡库区秭归盆地广泛分布以软硬相间地层为主的易滑地层,在长期的库水浸泡冲刷、降雨等作用下,地层岩土体发生劣化损伤,成为降低滑坡稳定和影响工程安全的重要内因。以软硬相间地层岩土体为研究对象,采用有限-离散元法(finite discrete...三峡库区秭归盆地广泛分布以软硬相间地层为主的易滑地层,在长期的库水浸泡冲刷、降雨等作用下,地层岩土体发生劣化损伤,成为降低滑坡稳定和影响工程安全的重要内因。以软硬相间地层岩土体为研究对象,采用有限-离散元法(finite discrete element method,简称FDEM)对不同干湿循环作用下软硬相间地层中硬岩和软岩的力学参数进行了标定,然后通过改进的泰森多边形程序进行了网格重划分,实现了零厚度黏聚力单元的嵌入功能,提出并建立了软硬相间地层滑坡-抗滑桩体系FDE.M数值计算模型,最后对不同干湿循环作用下滑坡裂纹的形成过程和抗滑桩的嵌固机理进行了研究。研究结果表明:(1)滑坡模拟裂纹数量随着干湿循环次数的增加而增多,裂纹宽度也逐渐增大,并与马家沟滑坡现场裂缝进行了对比,模拟结果与现场基本一致;(2)滑坡-抗滑桩体系的模拟裂纹呈现2种演化模式,一是裂纹从桩顶侧岩土体沿着桩身向下扩展,二是裂纹从抗滑桩周围逐渐向滑体内部延伸,与横向裂纹和竖向裂纹连通,最终形成大型的贯通裂纹;(3)当干湿循环次数增加时,抗滑桩桩身水平位移、弯矩和剪力也随之增加;(4)抗滑桩嵌固段的软硬相间地层基岩内的裂纹具有局部化发育特征,而且随干湿循环次数的增加,区域内的应力逐渐减小,位移和应变则逐渐增大,相应的裂纹也愈发密集。研究成果可为不同干湿循环作用下软硬相间地层滑坡防治提供技术支撑。展开更多
For rapid and cost-effective hammer drilling,accurate prediction of rock impact response is crucial for designing optimal bits and maximising rock fragmentation.Current design optimisation workflows combine numerical ...For rapid and cost-effective hammer drilling,accurate prediction of rock impact response is crucial for designing optimal bits and maximising rock fragmentation.Current design optimisation workflows combine numerical simulations and experiments but often require numerous iterations to pinpoint the optimal design.Although physics-based models can potentially reduce experimental expenses,their significant computational demands present challenges when simulating the complex fragmentation dynamics during drill bit-rock interactions.This study introduces a data-driven artificial intelligence(AI)model,employing a multilayer perceptron(MLP)as a surrogate.The model leverages the hybrid finitediscrete element model(FDEM)as a powerful method in rock fracture mechanics to generate a sufficiently large training dataset.An automated workflow has been developed for generating the training data,comprising a pipeline that includes pre-processing,solving,and post-processing modules.Subsequently,the AI models were integrated into an optimisation framework alongside uncertainty quantification to demonstrate their potential in enhancing drilling efficiency through optimised bit design and operations.The MLP exhibits high accuracy in predicting key parameters,including rebound velocity,total crack length,quantities of fragments with different sizes and maximum contact force between rock and insert.Notably,this approach achieves real-time prediction compared to the 5-7 min simulation times of FDEM.Integrating this data-driven model into a design framework enables rapid assessment of different bit designs under various operational conditions.More broadly,this approach has the potential to impact other applications,such as digital twins,serving as a forward and inverse model for predicting rock type and optimising drilling performance.展开更多
Percussive drilling is gaining interest for both shallow and deep applications due to its potential for higher drilling rates in hard rocks.Therefore,for efficient rock breaking,the development of advanced percussive ...Percussive drilling is gaining interest for both shallow and deep applications due to its potential for higher drilling rates in hard rocks.Therefore,for efficient rock breaking,the development of advanced percussive drilling simulation tools has the potential to be transformative.Such tools must accurately capture the rock’s response to enable an effective analysis of the fragmentation process.Traditional continuum numerical methods,such as the finite element method(FEM),do not simulate discrete cracks or the contact interaction between rock fragments.The finite-discrete element method(FDEM)is a three-dimensional hybrid method that combines FEM with the discrete element method(DEM)that addresses these limitations.New FDEM simulation results of impacts on Kuru Grey granite show good agreement with published experimental data.The interpretation focuses on two significant processes in percussive drilling:crack propagation and chipping generation.FDEM successfully simulates the evolution of cracks,including radial,side,and inclined cracks,as well as crushed and cracked zones.The simulation also reproduces the coalescence of adjacent craters to generate more chippings.Additionally,the stress state,velocity field and discrete fractures simulated by FDEM provide detailed insights into the different fracture patterns for Kuru Grey granite,enhancing understanding of the fundamental underlying mechanisms.展开更多
为了研究混凝土在轴向应力作用下的微裂纹萌生扩展过程和位移场、应力场的变化,采用有限-离散元法(Combined finite-discrete element method, FDEM)进行混凝土数值模型重构,生成了结构上含多边形随机骨料、砂浆和界面过渡区三相物质的...为了研究混凝土在轴向应力作用下的微裂纹萌生扩展过程和位移场、应力场的变化,采用有限-离散元法(Combined finite-discrete element method, FDEM)进行混凝土数值模型重构,生成了结构上含多边形随机骨料、砂浆和界面过渡区三相物质的数值模型。主要结论如下:(1)有限-离散元法可以很好地模拟混凝土在外部轴向荷载下开裂的全过程,包括微裂纹萌生、扩展、贯通等过程。(2)由骨料、砂浆和两者之间的界面过渡区造成的力学参数非均质性和混凝土内部结构的非均质性共同造成了混凝土位移场和应力场分布的不均匀性。且界面过渡区由于力学参数较为薄弱,最易萌生微裂纹,首先产生破坏。(3)非均质性会影响混凝土的局部应力场分布,造成应力集中现象。(4)FDEM能够较好地模拟高性能混凝土的拉压比(0.064),为更进一步模拟大尺度混凝土建筑物的工程特性打下良好的基础。展开更多
文摘三峡库区秭归盆地广泛分布以软硬相间地层为主的易滑地层,在长期的库水浸泡冲刷、降雨等作用下,地层岩土体发生劣化损伤,成为降低滑坡稳定和影响工程安全的重要内因。以软硬相间地层岩土体为研究对象,采用有限-离散元法(finite discrete element method,简称FDEM)对不同干湿循环作用下软硬相间地层中硬岩和软岩的力学参数进行了标定,然后通过改进的泰森多边形程序进行了网格重划分,实现了零厚度黏聚力单元的嵌入功能,提出并建立了软硬相间地层滑坡-抗滑桩体系FDE.M数值计算模型,最后对不同干湿循环作用下滑坡裂纹的形成过程和抗滑桩的嵌固机理进行了研究。研究结果表明:(1)滑坡模拟裂纹数量随着干湿循环次数的增加而增多,裂纹宽度也逐渐增大,并与马家沟滑坡现场裂缝进行了对比,模拟结果与现场基本一致;(2)滑坡-抗滑桩体系的模拟裂纹呈现2种演化模式,一是裂纹从桩顶侧岩土体沿着桩身向下扩展,二是裂纹从抗滑桩周围逐渐向滑体内部延伸,与横向裂纹和竖向裂纹连通,最终形成大型的贯通裂纹;(3)当干湿循环次数增加时,抗滑桩桩身水平位移、弯矩和剪力也随之增加;(4)抗滑桩嵌固段的软硬相间地层基岩内的裂纹具有局部化发育特征,而且随干湿循环次数的增加,区域内的应力逐渐减小,位移和应变则逐渐增大,相应的裂纹也愈发密集。研究成果可为不同干湿循环作用下软硬相间地层滑坡防治提供技术支撑。
基金supported by the European Union's Horizon 2020 research and innovation programme under grant agreement No.101006752(ORCHYD project).
文摘For rapid and cost-effective hammer drilling,accurate prediction of rock impact response is crucial for designing optimal bits and maximising rock fragmentation.Current design optimisation workflows combine numerical simulations and experiments but often require numerous iterations to pinpoint the optimal design.Although physics-based models can potentially reduce experimental expenses,their significant computational demands present challenges when simulating the complex fragmentation dynamics during drill bit-rock interactions.This study introduces a data-driven artificial intelligence(AI)model,employing a multilayer perceptron(MLP)as a surrogate.The model leverages the hybrid finitediscrete element model(FDEM)as a powerful method in rock fracture mechanics to generate a sufficiently large training dataset.An automated workflow has been developed for generating the training data,comprising a pipeline that includes pre-processing,solving,and post-processing modules.Subsequently,the AI models were integrated into an optimisation framework alongside uncertainty quantification to demonstrate their potential in enhancing drilling efficiency through optimised bit design and operations.The MLP exhibits high accuracy in predicting key parameters,including rebound velocity,total crack length,quantities of fragments with different sizes and maximum contact force between rock and insert.Notably,this approach achieves real-time prediction compared to the 5-7 min simulation times of FDEM.Integrating this data-driven model into a design framework enables rapid assessment of different bit designs under various operational conditions.More broadly,this approach has the potential to impact other applications,such as digital twins,serving as a forward and inverse model for predicting rock type and optimising drilling performance.
文摘Percussive drilling is gaining interest for both shallow and deep applications due to its potential for higher drilling rates in hard rocks.Therefore,for efficient rock breaking,the development of advanced percussive drilling simulation tools has the potential to be transformative.Such tools must accurately capture the rock’s response to enable an effective analysis of the fragmentation process.Traditional continuum numerical methods,such as the finite element method(FEM),do not simulate discrete cracks or the contact interaction between rock fragments.The finite-discrete element method(FDEM)is a three-dimensional hybrid method that combines FEM with the discrete element method(DEM)that addresses these limitations.New FDEM simulation results of impacts on Kuru Grey granite show good agreement with published experimental data.The interpretation focuses on two significant processes in percussive drilling:crack propagation and chipping generation.FDEM successfully simulates the evolution of cracks,including radial,side,and inclined cracks,as well as crushed and cracked zones.The simulation also reproduces the coalescence of adjacent craters to generate more chippings.Additionally,the stress state,velocity field and discrete fractures simulated by FDEM provide detailed insights into the different fracture patterns for Kuru Grey granite,enhancing understanding of the fundamental underlying mechanisms.
文摘为了研究混凝土在轴向应力作用下的微裂纹萌生扩展过程和位移场、应力场的变化,采用有限-离散元法(Combined finite-discrete element method, FDEM)进行混凝土数值模型重构,生成了结构上含多边形随机骨料、砂浆和界面过渡区三相物质的数值模型。主要结论如下:(1)有限-离散元法可以很好地模拟混凝土在外部轴向荷载下开裂的全过程,包括微裂纹萌生、扩展、贯通等过程。(2)由骨料、砂浆和两者之间的界面过渡区造成的力学参数非均质性和混凝土内部结构的非均质性共同造成了混凝土位移场和应力场分布的不均匀性。且界面过渡区由于力学参数较为薄弱,最易萌生微裂纹,首先产生破坏。(3)非均质性会影响混凝土的局部应力场分布,造成应力集中现象。(4)FDEM能够较好地模拟高性能混凝土的拉压比(0.064),为更进一步模拟大尺度混凝土建筑物的工程特性打下良好的基础。
