Formation-motion Mechanism Of The Loess Collapse In Fahua Temple,Xi'an City

It is well known that the loess collapses have caused serious damages to people's lives and property,but it is difficult to control effectively.The key is the mechanism of the loess collapse.Using a loess collapse in Fahua Temple,Xi'an City investigates formation,development,deformation and damage of the loess collapses to reappear the whole process.Formation-motion mechanism of the loess collapse is investigated quantitatively to control loess collapses effectively.The results obtained in this paper are as follows:(1)As to a loess collapse in Fahua Temple,Xi'an City,internal and external influential factors of the loess collapses are investigated.Internal influential factors consist of slope geometry,slope structure,vegetation action;External influential factors consist of rainfall action,earthquake action and engineering action.These results make it easy to investigate formation-motion mechanism of the loess collapse.(2)As to a loess collapse in Fahua Temple,Xi'an City,three kinds of formation mechanism of the loess collapse has been investigated.?Formation mechanism under the action of heavy rain:rainfall penetration,concentration-crack infiltration,filling-broken weak layer expansion,cutthrough-collapse.? Formation mechanism under the action of earthquake:seismic force action-the disintegration of the loess cutting body-get the initial speed-air cushion layer migration-collapse.?Formation mechanism under the action of human:engineering activities action-destroyed soil stress balance-heavy rains or seismic action-collapse body along the fracture surface endpoint dumping-collapse.(3)The mechanism of its toppling,falling and accumulation is presented,which composes of the start-up condition,motion equation and destruction form,etc and relevant parameters in evolvement processes.?Crack defomation stage:Under the effect of gravity,the top surface appears uneven settlement,tensile fracture at the top of the building.?Toppling stage:After water filling of joints,hydrostatic pressure in the slide torque surges,and the collapse body around the bottom of the dumping of moves.?Falling stage:Heart removed after slope collapse weight from mother to fall down whose process is under the oblique movement.?Accumulation stage:Collapse of the body after falling hits the ground to produce harm.(4)Using the discrete element method program recreates the collapse body movement process based on the movement of the collapse,including formation,toppling,falling and accumulation,and the collapse of the body's sphere of influence is determined under the action of the heavy rain,the heavy rain and earthquake.Compared with the results of actual value and the theoretical value,the result of numerical simulation under the action of the heavy rain and earthquake approaches actual value and the theoretical value.