Underground engineering often passes through water-rich fractured rock masses, which are prone to fracture and instability under the long-term coupling of in-situ stress field and pore water(P-W) pressure, ultimately ...Underground engineering often passes through water-rich fractured rock masses, which are prone to fracture and instability under the long-term coupling of in-situ stress field and pore water(P-W) pressure, ultimately threatening the stability of underground structures. In order to explore the mechanical properties of rocks under H-M coupling, the corresponding damage constitutive(D-C) model has become the focus of attention. Considering the inadequacy of the current research on rock strength parameters,energy evolution characteristics and D-C model under H-M coupling, the mechanical properties of typical sandstone samples are discussed based on laboratory tests. The results show that the variation of characteristic stresses of sandstone under H-M coupling conforms to the normalized attenuation equation and Mohr-Coulomb(M-C) criterion. The P-W pressure mechanism of sandstone exhibits a dynamic change from softening effect to H-M fracturing effect. The closure stress is mainly provided by cohesive strength, while the initiation stress, damage stress, and peak stress are jointly dominated by cohesive strength and friction strength. In addition, residual stress is attributed to the friction strength formed by the bite of the fracture surface. Subsequently, the energy evolution characteristics of sandstone under H-M coupling were studied, and it was found that P-W pressure weakened the energy storage capacity and energy dissipation capacity of sandstone, and H-M fracturing was an important factor in reducing its energy storage efficiency. Finally, combined with energy dissipation theory and statistical damage theory, two types of D-C models considering P-W pressure are proposed accordingly, and the model parameters can be determined by four methods. The application results indicate that the proposed and modified D-C models have high reliability, and can characterize the mechanical behavior of sandstone under H-M coupling, overcome the inconvenience of existing D-C models due to excessive mechanical parameters,and can be applied to the full-range stress–strain process. The results are conducive to revealing the deformation and damage mechanisms of rocks under H-M coupling, and can provide theoretical guidance for related engineering problems.展开更多
A direct algorithm is proposed by which one can distinguish whether a matrix is an M-matrix (or H-matrix) or not quickly and effectively. Numerical examples show that it is effective and convincible to distinguish M-m...A direct algorithm is proposed by which one can distinguish whether a matrix is an M-matrix (or H-matrix) or not quickly and effectively. Numerical examples show that it is effective and convincible to distinguish M-matrix (or H-matrix) by using the algorithm.展开更多
针对富水区土压平衡式盾构隧道施工进行了水-力耦合(H-M耦合)数值模拟。首先在既有的研究成果基础上建立了单元状态指标ZSI(Zone State Index),该指标将屈服、破坏接近度等进行适当变换,统一到单元安全度量体系(负值代表破坏),实现了单...针对富水区土压平衡式盾构隧道施工进行了水-力耦合(H-M耦合)数值模拟。首先在既有的研究成果基础上建立了单元状态指标ZSI(Zone State Index),该指标将屈服、破坏接近度等进行适当变换,统一到单元安全度量体系(负值代表破坏),实现了单元的弹性、屈服和破坏3种状态的完整表达。然后将应变-渗透系数方程与ZSI结合,使渗透系数在耦合的过程中随单元状态发生改变,弥补了FLAC^(3D)渗流模拟中渗透系数不变的不足。最后采用FLAC^(3D)的FISH语言二次开发,以大连地铁202标段香工街站-沙河口火车站区间盾构地铁隧道为例,实现H-M耦合过程的模拟。分析了隧道掘进的过程中开挖面及围岩的变形和破坏特征,根据开挖面上ZSI的计算结果对开挖面进行了稳定性评价。研究结果表明,该方法可以较好地进行H-M耦合过程中模拟和分析,与实测结果较为吻合。展开更多
基金funding support from the National Natural Science Foundation of China(Nos.52174088 and 42277154)the Independent Innovation Research Fund Graduate Free Exploration Project(No.104972024JYS0007)supported by Wuhan University of Technology.
文摘Underground engineering often passes through water-rich fractured rock masses, which are prone to fracture and instability under the long-term coupling of in-situ stress field and pore water(P-W) pressure, ultimately threatening the stability of underground structures. In order to explore the mechanical properties of rocks under H-M coupling, the corresponding damage constitutive(D-C) model has become the focus of attention. Considering the inadequacy of the current research on rock strength parameters,energy evolution characteristics and D-C model under H-M coupling, the mechanical properties of typical sandstone samples are discussed based on laboratory tests. The results show that the variation of characteristic stresses of sandstone under H-M coupling conforms to the normalized attenuation equation and Mohr-Coulomb(M-C) criterion. The P-W pressure mechanism of sandstone exhibits a dynamic change from softening effect to H-M fracturing effect. The closure stress is mainly provided by cohesive strength, while the initiation stress, damage stress, and peak stress are jointly dominated by cohesive strength and friction strength. In addition, residual stress is attributed to the friction strength formed by the bite of the fracture surface. Subsequently, the energy evolution characteristics of sandstone under H-M coupling were studied, and it was found that P-W pressure weakened the energy storage capacity and energy dissipation capacity of sandstone, and H-M fracturing was an important factor in reducing its energy storage efficiency. Finally, combined with energy dissipation theory and statistical damage theory, two types of D-C models considering P-W pressure are proposed accordingly, and the model parameters can be determined by four methods. The application results indicate that the proposed and modified D-C models have high reliability, and can characterize the mechanical behavior of sandstone under H-M coupling, overcome the inconvenience of existing D-C models due to excessive mechanical parameters,and can be applied to the full-range stress–strain process. The results are conducive to revealing the deformation and damage mechanisms of rocks under H-M coupling, and can provide theoretical guidance for related engineering problems.
基金Foundation item: This work is supported by the Science Foundations of the Education Department of Yunnan Province (03Z169A)the Science Foundatons of Yunnan University (2003Z013B).
文摘A direct algorithm is proposed by which one can distinguish whether a matrix is an M-matrix (or H-matrix) or not quickly and effectively. Numerical examples show that it is effective and convincible to distinguish M-matrix (or H-matrix) by using the algorithm.
文摘针对富水区土压平衡式盾构隧道施工进行了水-力耦合(H-M耦合)数值模拟。首先在既有的研究成果基础上建立了单元状态指标ZSI(Zone State Index),该指标将屈服、破坏接近度等进行适当变换,统一到单元安全度量体系(负值代表破坏),实现了单元的弹性、屈服和破坏3种状态的完整表达。然后将应变-渗透系数方程与ZSI结合,使渗透系数在耦合的过程中随单元状态发生改变,弥补了FLAC^(3D)渗流模拟中渗透系数不变的不足。最后采用FLAC^(3D)的FISH语言二次开发,以大连地铁202标段香工街站-沙河口火车站区间盾构地铁隧道为例,实现H-M耦合过程的模拟。分析了隧道掘进的过程中开挖面及围岩的变形和破坏特征,根据开挖面上ZSI的计算结果对开挖面进行了稳定性评价。研究结果表明,该方法可以较好地进行H-M耦合过程中模拟和分析,与实测结果较为吻合。
