| Slope stability is one of the main engineering geological problems of large-scale hydropower construction.The research of slope stability for the engineering construction smoothly and give full play to the project comprehensive benefit after the completion of the project is of great significance. Mengdigou hydropower station adopts hyperbolic arch dam concrete with height of 201 m.In this paper, on the basis of field geological investigation, analyzed the left abutment slope rock mass structure characteristic, system to study the slope rock mass quality classification and structure of surface engineering geology classification and form a complete set of physical and mechanical parameters, combined with the slope deformation and failure phenomena, established the corresponding slope deformation failure mode.Using rigid body limit equilibrium method and numerical simulation method for the stress and displacement in the process of slope excavation characteristics are analyzed, and for the design, construction and safe operation of the hydropower project construction to provide geological basis.Systematic evaluation of the stability of the slope engineering, get the following main.(1)The left abutment slope rock lithology for grain in early yanshan granite diorite gamma delta(γδ52), affected by multiphase tectonic activity, slope fracture development.Mainly in left abutment slope Ⅲ, Ⅳ small fault, extrusion, joint characteristics of dense zone and joints and fissures.Larger Ⅲ level including f1, f2 and f3, f6 and f8, advantage of its occurrence are mainly N60 ~ 80 ° W/NE∠ 70 ~ 80 ° and N60 ~ 80 ° E/NW ∠ 70 ~ 80 ° in the two groups.Grew up crack is visible(1) main N50 ~ 80 ° W/NE(SW) ∠ 65 ~ 85 °,(2) N50 ~ 85 ° E/NW ∠ 70 ~ 85 °,(3) N10 ~ 30 ° E/SE(NW) ∠ 60 ~ 90 ° 3 groups such as steep dip Angle fracture and Jh01, Jh02, Jh03 such as the slow crack.(2)The left abutment slope rock mass quality overall is good, give priority to with Ⅱ, Ⅲ rock mass.On the basis of slope rock mass quality classification, refer to mechanical parameters of rock mass quality classification in the specification, combining with laboratory test and field test data to determine the rock mass mechanics parameters.(3)The left abutment slope rock mass deformation and failure mainly for slip cracking destruction, along the Jh01, Jh02 dip Angle structure plane occur, the NWW dipping structural plane constitute adverse to the trailing edge cracking of a portfolio, NEE to grow up structural plane constitute lateral fracture surface, formed in the slope table shaped cavity landform in several steps.Status of the left abutment slope deformation damage degree is relatively weak, the natural slope overall stability is good, local potentially unstable block combination.(4)The left spandrel groove slope engineering potential sliding cracking unstable blocks, Jh01, Jh02 slope surface.slope, structural plane form bottom sliding surface, f1, f2 and f3 NWW to constitute a trailing edge cracking surface fault, NNE grew up to the steep dip Angle structure plane constitute a lateral fracture surface.Upstream side slope exists L2110 arch ring by HL03 slope surface.slope structure surface as the bottom sliding surface, NEE to f6 as cracking potential sliding cracking block below.(5)By FLAC3 D numerical calculation software for the stress, displacement and plastic zone in the process of slope excavation, the shear strain increment analysis shows that in the process of excavation, in f1, f2 and f3 fault and excavation face border areas appear tensile stress, and its value as the excavation step by step to increase gradually.The maximal displacement of excavation process appear in f1, f2, f3 and excavation face border area, after the third step excavation, excavation face and f3 junction horizontal direction pointing to the maximal displacement, the maximal displacement values of about 1 cm, should pay attention.Shear strain increment is mainly appear in the fault and Jh01 border slope surface.slope, and the excavation of the shear strain increment area along the f1 to slope deep inside, and the shear strain increment increases, from NWW to dipping fault f1 and flat structure surface Jh01 block relative to other parts of the composition, the stability is relatively poor.(6)For the left spandrel groove slope engineering stability problem, suggest that in the process of strengthening engineering of slope excavation of slope deformation monitoring, the unstable blocks should be handled timely support.Due to the project when there are random combination of structural plane of slope excavation potential instability controlled by small block, construction should handle and follow up. |
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