| During construction, the stability analysis results indicate that the stabilitycoefficient of the talus slope ahead of the dam is only1.001to1.005whileencountering the event of Ⅶ earthquake, the stability coefficient of the leading edgeof the slope is less than1. In order to improve the safety of the slope, a slag heapanti-pressure measure has been taken to control the leading edge of the slope. Afterthe Wenchuan earthquake, although the leading edge of the slope turned out somedeformation, the whole stability is good. Because of the importance of the Bank Slopesafety and the importance of the project location, we need to study the SeismicDynamic Response mechanism of the slope, and also need to review its stability.In this paper, the study object is the talus slope of the Zipingpu WaterConservancy Project. Based on the engineering geological conditions, the deformationbefore and after the Wenchuan Earthquake is analyzed; And the earthquake process isdynamically simulated by FLAC3D software and the simulation results are comparedwith the actual monitoring results about the earthquake; Finally, the stability of theaccumulation body has been checked as below:(1) Before the earthquake, the water level meter, osmometer and inclinometerwere all measured stable, indicating that the slope was in a stable state. After theearthquake, collapse of three small-scale surfaces has been observed about the leadingedge of the slope. Also, the inclinometer hole displacement has experienced bigchanges with the maximum displacement occurred around the orifice. The Wenchuanearthquake resulted in dislocation of the covering layer interface of the slope againstthe bedrock, and the dislocation and deformation of the surface above the slope wereaggravated with the increase of elevation. The earthquake has led to somedeformation of the talus slope, which is however in a stable state as a whole.(2) Since the actual variation of the slope stability conditions after the earthquakeis inconsistent with the previous research results, argument C and Φ are revised byanti-analyzing parameters of the slope and provided to the numerical simulation and stability analysis. Dynamic numerical simulation shows that during the the initialphase of dynamic loads imposition, the seismic dynamic response of the slope isobvious, which becomes weaker and weaker with the continuous vibration. There’reno instability phenomena that could be caused by slope displacement mutation orshear strain of the concentrated area. Monitoring point horizontal acceleration of theinitial phase in the earthquake response is more intense and at the same time, theacceleration of the high-elevation monitoring points has much stronger response thanthe low-elevation ones, and also the acceleration amplification factor is obvious.High-elevation monitoring points have bigger displacement value than thelow-elevation monitoring points and this demonstrates the seismic response of thealtitude effects. The comparative analysis of simulation results and measured resultsshows that the deformation trend is basically the same: either under natural conditionsor by imposing shock loading, the experimental displacement values, though slightlysmaller, are quite close to the measured ones.(3) Using the limit equilibrium method, the stability of two selectedlongitudinal profile of the accumulation body has been reviewed. And theconsolidated results of analysis shows that, after the heap ballast control of the leadingedge of the slope, both the entire slope and the leading edge of the slope have a quitestable resistance at the dead weight status. With the natural increase in seismicconditions, the slope is fairly stable. With water storage, slope stability is also good.Under the impoundment state of the Ⅷ seismic conditions, accumulation body is stillin a relatively stable state. Under the Impoundment plus Ⅸ earthquake, the overallslope stability decreases with stability coefficients all below1.1and thus the slopeenters non-stable state. Stability results review shows that the slope is not stable in thewater storage plus Ⅸ earthquake conditions. Although the slope didn’t becomeunstable after the Wenchuan earthquake, obvious deformation was observedindicating that the reviewed results basically meets the actual situation. |
PDF Full Text Request