Stability Analysis Of Deep Cut Slope In Bazhun Heavy Haul Railway Under Severe Rainfall Condition

Under the influence of rain, engineering accidents like slope instability often occurin some slope projects along the railway line, such as high fill subgrade slope, deep cutslope. Because the mass of earthwork in this kind of accidents is very huge and it occurswithout obvious signs, so once evoked, it often results in irreparable casualty andproperty damage. Therefore, it is quite necessary and has important academicsignificance and high practical value to evaluate and analyze the stability of deep cutslope along the railway line under the effect of rain.This thesis selects the typical section of Bazhun heavy haul railway deep cuttingsegment as research object. By using finite element method and on the basis of buildinginitial seepage field, it analyzed the variation of transient seepage field of cutting slopeunder precipitation condition, and analyzed the slope stability different moment bystrength reduction method. The main contents are presented as follows.(1) Refered to the detailed design of overloaded railway line in Bajuni, we selectedDK19+729fracture surface in the road section which riches in groundwater, andestablished a two-dimensional finite element model of deep cutting slope stabilityanalysis in rainfall conditions. Slope soil parameters considered the unsaturated role.Applying rainfall traffic load to think about the transient saturation effect of slopesurface when the rainfall is too strong. Analysed and calculated the variation of cuttingslope transient seepage field in the rainfall condition based on seepage field which weobtained initially. In addition, we use the pore pressure distribution, combinningstrength reduction to get the change of safety factor in the process of rainfall and thevariation of maximum shear strain. We found the safety factor increased when weestablished initial seepage considered groundwater level. However, the safety factorreduced continuely as the rain pogresses, and the maximum shear strength refined afterreducted the strength.(2) On the basis of the finite element model of cutting slope established in thispaper, the pressure head was taken as the main state variables, the thesis summarizedthe influence of the rainfall intensity, rainfall duration and the underground water levelon the transient seepage field of slope under the conditions of rainfall. The resultsshowed: with the increase of rainfall intensity, the depth of rainfall infiltration wasincreased and the speed of matric suction loss was quicken; Meanwhile, with theincrease of rainfall duration, the development of seepage field was slowed and thegroundwater level was raised, and the influence on slop was larger than the slopebottom. On the other hand, the groundwater level had little effects on seepage field.However, the higher groundwater level was,the quicker the development of the slope transient saturated zone, and then it would result in the large change of the seepagefield.(3) On the basis of transient seepage field, the pore pressure distribution data wasaccumulated to the stress field, and using strength reduction method, the slope stabilitywas analyzed under the above three factors during the rainfall process. With the increaseof the rainfall intensity, the safety factor of the slope was decreased; with the increase ofthe rainfall duration, the safety factor was decreased and to a certain extent, it would bemaintained at a certain range; the high groundwater level would significantly enhancethe sensitivity of safety factor, but the low groundwater level had little influence onsafety factor.