Exploration on Selection of the Most Unfavorable State for Seismic Stability Calculation of Gravity Retaining Walls
The selection of the most unfavorable state in the overall stability calculation of gravity re-taining walls has an important influence on seismic design.Shaking table model tests were used to re-veal the differences in seismic earth pressure values at three critical seismic moments for retaining walls,namely,peak acceleration,peak outward rotation of the wall,and peak displacement at the top of the wall.Also,an evaluation of the envelope method,commonly used to select values at the peak earth pressure moment,was conducted.Based on the seismic response calculations of gravity retain-ing walls by the ABAQUS finite element model,the differences in earth pressure values at the back of the wall and the overall stability calculation results at each critical moment were analyzed,and the most unfavorable state in seismic stability calculation was proposed.Research showed that:(1)With the increase of peak ground acceleration and wall height,the seismic earth pressure at the three critical moments all showed a transition from a non-linear distribution to an approximately equilateral triangu-lar pattern.The combined earth pressure and the height of its action point were,on average,49%and 18%greater,respectively,than those in the current seismic design codes.(2)Due to the inability of peak envelope method to reflect the active/passive state of wall-soil motion and the seismic wave prop-agation delay,the earth pressure values near the top of the wall were overly high,and the combined seismic earth pressure was twice as large as that at the critical moments,with the action point about 25%higher.(3)The anti-slide stability coefficient at the moment of peak wall outward rotation was 14%～33%smaller than the other two,and the sensitivity to attenuation was more obvious with the increase of peak ground acceleration.Therefore,selecting the critical moment of peak wall outward ro-tation as the most unfavorable state in seismic stability calculation is deemed to achieve a balance be-tween structural safety and cost-effectiveness.
gravity retaining wallseismic designoverall stabilitythe most unfavorable statefinite el-ement analysis
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