不同微震震源机制下地下硐室围岩响应及支护建议

Response and support suggestions of surrounding rock of underground cavern under different microseismic source mechanism

随着铁路、水利、矿山等工程的发展,越来越多的硐室需要在深部开挖。工程爆破开挖和断层滑移等动力荷载严重影响着地下硐室围岩的稳定性。利用有限差分软件FLAC3D,对地下硐室在爆破和断层滑移作用下的围岩稳定性进行模拟,引入地震动峰值速度(peak ground velocity,PGV),利用萨道夫斯基公式和McGarr公式拟合得到不同震源机制下围岩PGV的数学关系式。结果表明,在爆破荷载作用下,地下硐室与震源间的距离对硐室稳定性影响显著,萨道夫斯基变形公式可以很好的表征围岩体响应的PGV,但McGarr变形公式不适用;在断层滑移作用下,萨道夫斯基变形公式和McGarr变形公式拟合度低,滑移角度对硐室的稳定性影响更大。深部地下硐室支护应考虑震源的影响,如PGV等,对于断层滑移产生的震源需要考虑滑移角度对PGV的影响。以上结论为岩土工程地下硐室开挖及支护提供数据支撑与理论依据。

With the development of railway,water conservancy,mining and other projects,increasing caverns need to be excuvated in the deep.Dynaimic loads includying blasting excavation and fault-ship burst seriavsly affect the stability of surrounding rockmass of undergroud cavern.The finite difference software FLAC3D was used to simulate the surrounding rockmass stability of underground cavern under blasting and fault-slip burst conditions.The peak ground velocity(PGV)was used,and the mathematical relationship of the surrounding rock PGV under different focal mechanisms was obtained by fitting the Sadov's formula and the McGarr's formula.It was concluded that under the blasting load condition,the distance between the underground cavern and the source had a significant influence on the stability of the cavern.The Sadov's deformation formula could well characterize the PGV of the surrounding rockmass response,but the McGarr's deformation formula was not applicable.Under the condition of fault-slip,the Sadov's deformation formula and the McGarr's deformation formula did not have high goodness of fit,the slip angle had a greater influence on the stability of the cavern.Based on the above analysis,it was recommended that deep underground cavern support should consider the influence of the source,such as PGV.For the source of fault-slip,the influence of the slip angle on PGV should be considered.The above conclusions provide data support and technical basis for the excavation and support of geotechnical engineering underground cavern.