以H-B强度准则为基础的岩体力学参数估算方法综合考虑了岩体结构、岩块强度、应力状态等多种因素的影响,可更好地反映岩体的非线性破坏特征。以锦屏二级深埋大理岩为例,引入深部岩体完整性系数KV改进深部岩体GSI值确定方法,在此基础上详细分析了这一估算方法对深部工程岩体的适用性。结果表明:H-B强度准则中4个参数互相独立,且与围压应力状态无关,应用于深部岩体力学参数的估算是可行的;深部岩体完整性系数KV可反映岩体内部各种结构面的发育程度和岩体开挖受扰动程度,岩体完整性系数KV的引入,使深部岩体GSI值的确定更加客观;采用室内常规三轴试验结果参数σci和mi的值是比较合适的。采用上述方法估算获得锦屏深埋大理岩的强度包络线表现出明显的非线性,在中高围压阶段 (15 MPa<σ3<40 MPa),其内摩擦角降低了32%,但黏聚力则是低围压阶段的近3倍。
Abstract
The estimation method of rock mechanic parameters based on Hoek-Brown strength criterion could well reflect the nonlinear failure characteristics by taking into account multiple factors such as rock structure, rock block strength, rock mass stress state, etc. With the deep marbles at Jinping project as a research case, the intactness coefficient KV of rock mass is introduced to improving the determination of GSI (geological strength index) value of deep rock mass, and the applicability of this estimation method to deep rock mass is analyzed in detail. Results indicate that the Hoek-Brown strength criterion is feasible in estimating the mechanics parameters of deep rock mass as the four parameters in Hoek-Brown strength criterion are independent and have no correlation with confining pressure state. The intactness coefficient KV of rock mass enhances the objectivity of determining GSI value as it reflects the discontinuities development in rock mass and the excavation disturbance. It is appropriate to calculate parameter σci and mi according to indoor triaxial test results. The envelope curves of Jinping marbles obtained by the method are apparently nonlinear. Under high confining pressure state (15 MPa<σ3<40 MPa), internal friction angle of Jinping marbles decreases by 32%, while cohesion is 3 times that under low confining pressure state.
关键词
深部岩体 /
H-B强度准则 /
地质强度指标 /
岩体完整性系数 /
力学参数
Key words
deep rock mass /
Hoek-Brown strength criterion /
GSI /
intactness of rock mass /
mechanics parameters
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