不同岩桥角度双裂隙砂岩单轴蠕变试验及三维数值模拟  

Uniaxial creep test and three-dimensional numerical simulation of double flawed sandstone with different rock bridge angles

作　　者：杨超[1] 王娇 董星辰 王乐华[1] 王瑞红[1] YANG Chao;WANG Jiao;DONG Xingchen;WANG Lehua;WANG Ruihong(Key Laboratory of Geological Hazards on Three Gorges Reservoir Area,Ministry of Education,China Three Gorgers University,Yichang,Hubei 443002,China)

机构地区：[1]三峡大学三峡库区地质灾害教育部重点实验室,湖北宜昌443002

出　　处：《岩石力学与工程学报》2023年第10期2466-2477,共12页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(51979151);湖北省自然科学基金项目(2021CFA090,2021CFB536)。

摘　　要：为分析不同应力路径下岩桥角度α对岩体强度和破坏特征的影响规律,通过制备7种含不同α的双裂隙砂岩试样,依次开展常规单轴和单、多级蠕变试验。试验结果显示:α对试样的特征应力存在较大影响,但同类型岩体各特征应力之间的比例受α的影响较小;各岩体试样的长期强度σL与对应起裂应力σci非常接近,可将σci看成岩体的长期强度,从而只需通过常规压缩试验便可估算岩体σL值。裂纹扩展方面,α相同的试样在4种加载路径下的贯通特点基本一致:α=0°~45°试样破坏时岩桥均未贯通,而α=60°~90°试样则均呈现岩桥直接贯通破坏的模式。表明α对裂纹扩展的影响要大于应力路径的影响。另外,部分试样还呈现出表观裂纹和内部裂纹扩展并不一致的现象,鉴于此,基于连续介质单元模拟,提出一种基于塑性应变的裂纹扩展判断方法,并建立三维模型进行计算,模拟结果显示与试验结果较为一致。该方法较传统通过塑性区判断裂纹扩展更为准确,可为岩体裂隙的三维时效扩展模拟提供一定的参考和借鉴。To analyse the influence of rock bridge angleαon the strength and failure characteristics of rock mass under different stress paths,seven kinds of double flawed sandstone samples with differentαwere prepared,then uniaxial compression tests,single and multi-stage creep tests were carried out.Results show that the rock bridge angleαhas significant effect on the critical stress,but the ratio of the critical stress of the same sample is less affected byα.The long-term strength Lσof the samples is very close to the crack initiation stress ciσ,thus the longterm strength of the rock mass can be estimated only through the conventional compression test.In terms of crack propagation,the penetration characteristics of the same samples under the four loading paths are basically the same:the rock bridge is not penetrated when the samples withα=0°-45°are damaged,while the samples withα=60°-90°show the mode of direct penetration failure of the rock bridge.It is shown that the influence ofαon the crack propagation is greater than that of the stress path.In addition,some samples also show the phenomenon that the apparent crack and the internal crack propagation are not consistent.In view of this,based on the continuous medium element simulation,a crack propagation judgment method based on plastic strain was proposed,and a three-dimensional model was established for calculation.The simulation results show that they are consistent with the test results.This method is more accurate than the traditional method of judging the crack propagation through the plastic zone,and can provide some reference for the three-dimensional time-dependent propagation simulation of rock fracture.

关 键 词：岩石力学 双裂隙砂岩 单轴蠕变试验 强度特征 三维数值模拟 

分 类 号：TU45[建筑科学—岩土工程]