Forming Mechanism Of The Mudflow-landslides In Loess Triggered By The Earthquake

A great deal of mudflow-landslides in loess were triggered by an Ms 6.7 earehquake that happened on 22 July in the Minxian of the Gansu Province.,which caused 95 casualties and severe economic loss.Here we use the typical mudflow-landslide in loess,based on the methods of site investigation, sampling, test simulating to study the typicalits forming mechanism,by which we get some valuable conclusions.(1)Further defined the definition of the mudflow-landslides in loess and analyzed the characteristics of such landslides.(2)Put forward.the forming conditions of mudflow-landslides in loess,which had included the topography condition, rock and soil condition, water condition.(3)Based on the topography, lithology, rainfall, human activity, earthquake and other factors to analyze the causes of the Yonggung landslide.(4)Here we used the Geo-Studio to simulate thelandslide and the results showed two conditions. Before the earehquake, the stress field of the slope is normal for its had only the effect of the gravity and its stability factor is 2.824; both the earthquake and the water-power had effect on the loess liquefaction which made hole water pressure increase and loess dead weight rose and caused loess landslides iquefilied.with the ongoing of the earehquake,the liquefaction zone was formed finally.(5)Based on the dynamic response effect experiment of the saturated loess under the earthquake to study the liquefied mechanism. Analysis of the results of the experiment,we divided the liquefaction process into three stages, namely including the elastic strain stage, plastic strain stage, and liquefaction damage stage..(6)Put forward.the liquefied-crack mechanism of the the mudflow-Landslides in loess triggered by the earthquake. Because of the irrigation water infiltration and heavy rain before the earthquake,the soil of the slope was in a saturated condition. both the earthquake and the water-power had effect on the loess liquefaction which made hole water pressure increase and loess dead weight rose and caused loess landslides iquefilied.with the ongoing of the earehquake,the liquefaction zone was formed finally.Then the slope deformated and the tension fracture formed at the trailing edge. Then the crack surface and the liquefaction zone perforated, which was the weak sliding surface of the slope.(7)Put forward.the movement mechanism of the the mudflow-Landslides in loess triggered by the earthquake.Based on theNewmark sliding displacement analysis model and kinematic model to calculate the seismic slope displacement S1, start speed V1, and the slide Mizoguchi corner of the slippage distance S2 after the earthquake. Then I made a study on the characteristics of the movement of the slope. Landslide along the slope strong shear contraction effect- slip zone soil structure was damaged, was mud flow state- encounter barriers see phenomena climbing and cornering- along the U-shaped channel closed, increasing liquefaction occurs remote slide- Mizoguchi Office sector accumulation.