摘要
确定工程中岩体所处的应力场环境是灾害监测预警与应用的基础,在微震震源机制解的基础上探索采用联合迭代反演方法反演应力场,该方法采用不稳定性系数I作为约束结合经典的线性反演方法反演应力场,有效避免了两个断层面的模糊性对反演结果的不利影响,提高了反演精度。通过多次反演选取能够产生最大不稳定性系数的摩擦系数μ作为岩体的摩擦系数,并通过应力与摩擦系数定义了主破裂面。对一起典型的岩体破裂微震定位事件案例,首先分析了破裂类型以及破裂面方位,并对破裂的时间演化进行了推测;其次分析了加入不同程度噪声对应力反演结果的影响,并给出了分析结果;最后对应力场分布进行了分析,结果表明最大主应力轴的方位角与倾角为229.86°/48.57°;中间主应力轴的方位角与倾角为353.89°/26.28°;最小主应力轴的方位角与倾角为100.08°/29.44°,应力的分布与震源机制解P/T轴分布具有一致性;主破裂面的方位较好地符合了此次微震事件实际监测结果。
Determining the stress field environment of rock mass in engineering is the basis of disaster monitoring,disaster warning and its application.A joint iterative inversion method is used to retrieve the stress field based on the focal mechanism.The method uses instability coefficient I as a constraint and combines it with the classical linear inversion method to retrieve the stress field,which can effectively avoid the negative influences of the fuzziness of the two fault planes on the inversion results and improve the accuracy of the results.To determine the optimal friction coefficient of rock mass,the friction coefficient which can produce the maximum instability coefficient is selected as that of rock mass through multiple inversion.The concept of the main fault plane is defined by the friction coefficient and stress.A typical case of rock fracture microseismic location event is presented and analyzed.Firstly,the source mechanism is analyzed,the type of fracture and the orientation of the fracture surface are obtained,and the time evolution of the fracture is predicted.Secondly,the error of the stress inversion results with different levels of noise is analyzed,and the results are presented.Finally,the distributions of stress filed are analyzed,and the results show that the azimuth angle and inclination angle of the maximum principal stress axis are 229.86°and 48.57°.The azimuth angle and inclination angle of the intermediate principal stress axis are 353.89°and 26.28°.The azimuth angle and inclination angle of the minimum principal stress axis are 100.08°and 29.44°.The distribution of stress axes is consistent with the P/T axes of the focal mechanism.The orientation of the main fault plane is in great agreement with the actual monitoring results.
作者
唐超
李庶林
周梦婧
刘胤池
TANG Chao;LI Shu-lin;ZHOU Meng-jing;LIU Yin-chi(School of Architecture and Civil Engineering,Xiamen University,Xiamen 361005,China)
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2021年第9期1730-1738,I0005,I0006,共11页
Chinese Journal of Geotechnical Engineering
基金
国家自然科学基金项目(51674218)。
关键词
微震监测
应力场反演
震源机制
矩张量
岩体破裂
microseismic monitoring
stress field inversion
focal mechanism
moment tensor
rock mass fracture
