| Jiaokui town landslide is located in the Midwest of Yiliang.The average rainfall in the North reaches 1120 mm,the average rainfall in the south is 892.4mm,and the Yiliang is located in the Da guan-Ma bian seismic belt.The earthquake frequency is more and the magnitude is larger.The landslide threatens about more than 1000 people.Therefore,it is of great significance to analyze the effects of rainfall infiltration and seismic action on the stability of Jiaokui town landslide.In this paper,the field survey and engineering geological surveying are carried out,and the shape and boundary of the landslides of the Jiaokui town landslide are found out.The material composition and the average thickness of the landslide are revealed by drilling.The formation mechanism and failure mode of the landslide are analyzed.The indoor soil test is carried out,and the rainfall infiltration,the earthquake action,and the rainfall infiltration and comprehensive seismic action are analyzed.The effects of rainfall infiltration and seismic action on the stability of Jiaokui town landslide are as follows:1?The Jiaokui town landslide is a rock slope with a plane shape in the form of a circle chair,along the south to north,the landslide is about 1200 m in width and 800 m in length,the main sliding direction is 300 degrees,the area is 96 × 104 m2,the thickness of the slide is 10 to 30 m,the average thickness is 20 m,and the volume is about 1920 ×104m3,which belongs to the super large landslide.2?The landform of the Jiaokui town landslide is a slope landform,which is passed through the Luoze River in the front edge,and the steep cliff is exposed in the back edge,and the surface water is easy to infiltrate,which provides topographic and geomorphic conditions for the development of the landslides.3?The material composition of landslide is mainly composed of surface gravel containing silty clay and lower old landslide slide and disintegrate sand and mudstone block.The sliding bed is sand mudstone of suining group.The lower bedrock is cut off along the original rock slide surface from the outlet of the steep slope of the highway,and the loose bulk of the middle front slides along the underlying interface.4?The soil displacement and pore water pressure of the Jiaokui town landslide in natural condition are obtained.Generally speaking,the displacement of the top layer of the landslide is greater than that of the bottom of the landslide in natural state.By means of finite element analysis,the displacement and pore water pressure of the natural state are obtained,and the sliding surface is further found out by means of the limit equilibrium method.5?The law of pore water pressure variation with rainfall intensity is obtained.(1)The slope foot is easy to accumulate water,when the rainfall intensity increases,the pore water pressure increases and the water level increases.(2)The pore water pressure in the landslide increases with rainfall intensity.The longer the rainfall time,the greater the pore water pressure in the landslide.(3)When the rainfall stops,the pore water pressure in the landslide decreases as a whole.However,due to the influence of seepage from other parts of the slope,the pore water pressure increases,and then decreases.6?The law of the stability of the Jiaokuitown landslide with rainfall intensity is obtained.(1)The stability of Jiaokui town decreases with increasing rainfall intensity.But rainfall infiltration is a process,when the rainfall time is relatively short,the landslide is still in a relatively stable state.(2)When the duration of rainfall increases,the greater the rainfall infiltration,the greater the area affected by infiltration and rainfall,and the stability of landslide will be reduced.Rainwater infiltration partially saturated some soil.With the continuous rainfall,the decrease of landslide stability coefficient decreased.(3)During a rainfall process,the stability of the landslide decreases with rainfall,and the stability will continue to decrease within a certain time after the termination of rainfall.With the increase of rainfall termination time,landslide stability has been restored.7?Under the natural condition,the stability of Jiaokui town landslide has changed with the change of seismic intensity.(1)The horizontal displacement,vertical displacement and total displacement of the Jiaokui town landslide increase with the increase of the earthquake intensity,and the stability coefficient of the landslide decreases with the increase of the earthquake intensity.(2)The maximum shear strain of Jiaokui landslide increases with the increase of seismic intensity.The most dangerous sliding surface is changed due to the dynamic action of the earthquake.(3)The excess pore water pressure of the in Jiaokui town landslide increases with the increase of seismic intensity.(4)The Jiaokui town landslide is still relatively stable when the earthquake intensity is 6 degrees.When the earthquake intensity is 7 degrees,the landslide is relatively stable.8?For the first two cases of the first earthquake and the first rainfall after the earthquake,the deformation characteristics of the slope after rainfall infiltration and earthquake action are obtained.(1)When the seismic intensity is the same(7 degrees),the deformation of the Jiao kui town landslide will increase with the increase of rainfall intensity.(2)When the rainfall intensity is the same(80mm/d),the deformation of the Jiao kui town landslide will increase with the increase of seismic intensity.(3)Under the combined action of rainfall infiltration and earthquake,the deformation of Jiaokui town landslide is larger than that of single factor.9?For the two cases after the first rain and the first rainfall after earthquake,the change characteristics of the landslide stability under the combined action of rainfall infiltration and earthquake are obtained.(1)When the seismic intensity is the same(7 degrees),the stability of Jiaokui town landslide will decrease with the increase of rainfall intensity.When the rainfall intensity is 40mm/d,80 mm/d and 160 mm/d,the landslide mass is in an unstable state.(2)When the rainfall intensity is the same(80mm/d),the stability of the Jiaokui town landslide decreases with the increase of seismic intensity.When the earthquake intensity is 6 degrees,7 degrees and 8 degrees,the landslide bodies are in an unstable state.(3)Under the action of rainfall infiltration and earthquake,the initial earthquake causes the slope to form different size displacement,which provides good conditions for the infiltration of rain water,and is more conducive to the deformation of the slope.Therefore,the stability of the landslide in the first earthquake is worse than the stability of the landslide when the earthquake is first reduced after the rain. |
PDF Full Text Request