等效岩体三维随机节理网络模型构建及其在两河口水电站中的应用

Construction of a 3D equivalent rock random fracture network model and its application in the Lianghekou Hydropower Station

节理的存在对水电高陡岩质边坡的力学性质有重要影响,如何构建反映三维节理分布特征的等效岩体计算模型,是分析与评价岩体力学特性的关键.本文基于损伤力学和统计强度理论,在三维岩石破裂过程分析(RFPA^(3D))软件的基础上,提出了一种计算等效岩体三维随机节理网络模型的新方法.首先,基于Baecher模型和Monte-Carlo方法,在RFPA^(3D)软件中实现了三维随机离散节理网络(Discrete fracture network,DFN)模型的重构.然后,利用RFPA^(3D)软件内嵌DFN模型,赋予节理和岩石不同的力学参数,构建了工程尺度等效岩体三维随机节理网络模型,实现了三维随机节理岩体破裂过程、变形和强度等力学性质的分析.最后,以两河口水电站左岸边坡坝址区下游节理岩体为研究对象,验证了三维随机DFN模型的准确性,开展了研究区内节理岩体尺寸效应研究,并获得了研究区内岩体的表征单元体(Representative elementary volume,REV)和等效力学参数.该研究成果为等效岩体力学行为分析提供一种新方法.

The existence of fractures has a considerable influence on the mechanical properties of hydropower high and steep rocky slopes.The method to construct an equivalent rock mass calculation model that reflects the distribution characteristics of three-dimensional(3D)fractures is the key to analyze and evaluate the mechanical properties of rock mass.Based on the theory of damage mechanics and statistical strength,this study proposed a new method to calculate the equivalent rock 3D random fractured network model using the 3D rock failure process analysis(RFPA^(3D)).First,based on the Baecher model and Monte-Carlo method,the reconstruction of the 3D random discrete fracture network(DFN)model was implemented in the RFPA^(3D).Furthermore,an equivalent rock 3D random fractured network model of engineering scale was constructed using the embedded DFN model and through giving different mechanical parameters to fractures and rocks.All the types of load combinations can be applied to the model to realize the analysis of the mechanical properties,such as failure process,deformation,and the strength of the 3D random fractured rock mass.The rock mass downstream of the dam site area of the left bank slope of the Lianghekou Hydropower Station was then taken as the background,and the geometric parameters of the joints in the region were analyzed and studied using the 3GSM software.Moreover,the characteristic values and the distribution types of joint geometric parameters in the study area were obtained.Finally,the accuracy of the 3D random DFN model was verified by taking the fractured rock mass downstream of the left bank slope dam site of the Lianghekou Hydropower Station as an example,and the size effect of the fractured rock mass in the study area was studied.Results show that the representative elementary volume of the jointed rock mass is evaluated as 8 m×8 m×8 m,and the corresponding equivalent uniaxial compressive strength and elastic modulus are 25.159 MPa and 19.443 GPA,respectively.Research results provide a new method for the study of the mechanical behavior of the equivalent rock mass.