Study On Recognition And Stability Assessment Of Key Block For The Support Of High Rock Slope

For high rock slopes, especially with the long and huge joints developed, the failure of rock mass is always caused by the cutting of discontinuities and free face. This failure will severely influence the whole stability of the slope and the safety of construction. The basic method for the assessment of block stability is Block Theory. The first step to the assessment of block stability with Block Theory is to check out the existence of key blocks. But at present, there is not an effective way to check out the key block quickly and automically at the first time. Thus, combining slopeâ… -1 andâ…¡-9 of Tantun expressway, this thesis discussed the recognition of key blocks with Discrete Element Method, and the supporting design for blocks with SASW, which was based on Block Theory. The main research content and main achievements were represented as follows:(1) Realizing the modeling of complicated blocks by ANSYS, which has the Powerful function of modeling; Meanwhile, programming the interface device between ANSYS and 3DEC, taking out the solution of stability evaluation of blocks using 3DEC; Succeessfully check out the key block using 3DEC;Then carry out the stability check of key blocks through SASW, also, its sensitivity of stability under several conditions; Meanwhile an effective design is carried out; A simulation-validation for supporting measure is then carried out by 3DEC to check the effectiveness of the supporting design.(2) Carrying out the systematical description and study of discontinuities, such as extruded plane and joints, also making the analysis of possible deformation and failure mechanism. It was known that the fragment-blocked structure on Tunxi side of Slopeâ… -1 and the key blocks that were created through the combination between main joints and the slope surface on the opposite side took a control effect on the stability of the slope; The combinatorial characterization of weak silt inter-bed and joints of Slopeâ…¡-9 might form key blocks with larger volume.(3) Based on the modeling method above, checking out the locations of key blocks of Slopeâ… -1 andâ…¡-9; Carrying out the displacement analysis of typical section. It was proved that the stability of those blocks was so poor that a reliable supporting design was needed timely for these two slopes.(4) The stability check of key blocks through SASW software gave the same evaluation result. Its sensitivity of stability under several conditions was also checked. Consequent conclusion was that blasting and earthquake took a distinctive effect on the stability of blocks. Meanwhile an effective design was carried out.(5) A simulation-validation for supporting measure was carried out by 3DEC, and it was obtained that deformation of the slope had been prevented, because of the great effect of the anchor measure. The alignment between the simulation and monitoring information verified the feasibility of this method above.In total, this method of taking advantage of DEM to check out the key blocks, and utilizing Block Theory to carry out the supporting design is an effective solution to the stability evaluation for blocks of high rock slopes.