Study On Deformation Mechanism And Static-Dynamic Response For The Dam Area Slope Of Dagangshan Hydropower Station

With the implementation of western development strategy and the west-east electricitytransmission project, more and more large-scale water conservancies and hydro powerprojects began to build, the problem of the high rock slope gradually become an issue in thegeological engineering academics. The rivers in western area are usually in the conditions ofdeep canyon, steep terrain, high level of crustal stress and complex geologicalbackground. How to make sure the safety of excavation in operation period becomes animportant significance to both national strategic and economic development. This articleselected the right bank slope of Dagangshan Hydropower Station for the study, based onlong-term field research and laboratory test analysis, with the method of qualitative evaluationand calculation, this paper focus on the deformation characteristics and the stability underdynamic and static conditions of the right bank slope.Dagangshan Hydropower Station located in the middle reaches of the Dadu River inShimian county, the14th cascade hydropower stations of the22programs recommended forthe planning and adjustment of the Dadu River mainstream, the maximal height ofDagangshan arch dam is210m and the total capacity is742million cubic meters which hold ainstalled capacity of2600MW. Both sides of dam site are steep mountain valley slope,exposed bedrock and generally40°to65°natural grade. Most of the bedrock are Chengjianggranitoids, gray and reddish biotite monzonitic granite are widely distributed, in addition tovisible diabase veins (β), granitic aplite veins (γι), diorite dykes (δ), various types of dikesrock developed in the granite, especially distribute large of diabase veins, superior crustalstress, rock near the bank slope to the direction of the valley airport direction unloadingstrongly. Dam area without a regional fracture cut, the tectonic type characterized by extrudedalong the dikes in the development of fracture zone, faults and jointed fissure.The growth characteristics of the faults, diabase dikes and deep unloading fissures of theright slope are summarized in this paper. Through the investigation and analysis of the slopelithology characteristics, structure surface types, the structure of the engineering geologicalproperties and features, Through the investigation and analysis of the slope lithology characteristics, structure surface types, the structure of the engineering geological propertiesand features, the possible failure mode of the right bank slope is confirmed, and the mostunfavorable combination of structural surface is also ultimately determined for follow-upquantitative calculation. On this basis, this paper establishes the concept model ofdeformation and failure of the slope, determines the cause of the deformation and failure signthrough the study of the development rule of deformation and failure phenomenon of theslope and the analysis of deformation signs in the process of slope excavation, and sets upanalysis mode of deformation and failure of the right slope.The geology-mechanical-mathematical model of the right bank slope is comprehensivelyestablished on the basis of geological survey and qualitative analysis. From the stabilitycoefficient of the slope quantitative calculation and the development trend of deformationstatic perspective, the article evaluates slope angle the stability of the slope excavationsituation by means of the method of qualitative analysis, through the two dimensional limitequilibrium calculation, analyses the most unfavorable combination right bank namely faultf231+unloading fissure XL316-1at the end of the sliding surface block in supporting eachmode of the before and after the stability conditions, meanwhile by making use of traditionalstrength reduction in the numerical simulation dynamic strength on method of analysis andcombining with field monitoring data, analyzes the deformation characteristics of the slopedeformation modes and support effects, and results show that the right bank slope failuremode, that is, f231and unloading cracks XL316-1composed of large deformation f231cutexport position along the foot of the slope gradually upward through and reach the γL6position, block the overall incidence of damage. However, seen from the effect of supporting,deformation timely control gradually converge over time, proved effective. Numericalsimulation of seismic dynamic conditions: on the one hand, the role of the level of seismicwaves within the slope, especially the potentially unstable chunk of body stress magnitudeincreases, the slope superficial tensile stress area is significantly increased and prone to tensilefailure; On the other hand, after the level of support the slope displacement value reducedsignificantly, and that the shear hole seismic dynamic role in support of horizontaldisplacement are clearly inhibition effect, shear hole supporting effect is obvious.Finally, make a suggestion after a comprehensive analysis right slope: the right bank ofthe deep unloading fracture and the rest of the fault supporting work should continue toimprove the stability of the whole right bank, should strengthen monitoring work to the deepfissure and fault when excavating shear hole and blasting work, depending on the monitoringsituation, adjust blasting system parameters or construction method, etc, to ensure theconstruction safety.