Study On Stability And Key Technology Control Of The Waste Slag Field In Mountainous Expressway

With the continuous construction of highway in mountainous area,the waste slag of excavation and construction along the road is increasing.Usually,due to the terrain and construction costs,the waste residue is processed according to the principle of proximity,which is bound to affect the local environment.The highway slag field in mountainous areas is a destructive subsidiary project derived from the highway construction process,and its unstable landslide is a common type of disaster,which poses a great threat to the safe operation of Mountain Expressway and the ecology along the route.Therefore,it is of great significance to study the stability and key technology control of the waste slag field in mountainous expressway.In this paper,focusing on the waste slag’s characteristics in mountainous expressway,including large amount of rock mass,loose nature,poor engineering performance,poor anti-slide ability and easy infiltration of rainfall,With the aid of finite element numerical simulation software Midas GTS NX two-dimensional modeling,limit equilibrium theory,elastic-plastic deformation theory,stress analysis method,finite element strength reduction method,saturated-unsaturated seepage and other theoretical methods,Based on,the stability and stacking optimization design of the highway slag field in mountainous areas is studied based on the Q-6 waste slag field of Zhanyi-Huize Highway in Yunnan Province with these means of field research,experimental research,theoretical analysis,and the combination of numerical simulation and the numerical simulation.and,the results are as follows:(1)The basic types of the waste slag field in Mountain Expressway can be classified according to the source,location and stacking form of the slag body.In this paper,the heap form of the waste slag field is studied,and the slag field can be divided into the single-step and the multi-step dumping field according to its stacking form.The former consists of two basic forms,and the latter includes five basic forms.Based on the analysis of the single-step and the multi-step waste slag field under deadweight condition,the stability of the multi-step is better than that of the single step,and the displacement and strain change of the multi-step slag field are less than the single-step.(2)The two types of heap load are different according to the stacking order,According to the different stacking sequences and the average value of the safety factors in thestacking process of the waste slag yard,the two types of stacking are sorted as:the multi-step coverage;the multi-step and layer-by-layer stacking;the single-step coverage;the combined type two;the multi-step pressure foot type;the single step pressure foot type;the combined type one;in consideration of the final value and the minimum value of the stability coefficient,the selection sequence in the actual construction process should be as follows:the multi-step cover type;the multi-step stacking type;the modular two;the single-step cover;the multi-step pressure slope foot type;the combination one;the single-step pressure slope foot type.(3)Under the same rainfall in different rainfall duration,the effect of 96 h 2.5mm/h rain on slope stability is greater than that of 6h 40mm/h rain.In the case of rainfall-earthquake coupling,the safety of the slope is weakened with the increase of seismic wave acceleration,and the slope safety is less affected by the acceleration of seismic wave after the slope reaches the ultimate failure state.(4)With the increase of seismic wave loading time,the safety factor of the slope of the waste slag yard decreases gradually,and the slope stability is weakened.Only under the action of the earthquake,the extreme destruction of the waste slag field lags behind the peak acceleration by 10~13s.However,under the coupling of rainfall and earthquake,during the 8~9 seconds before the seismic wave is loaded,the stability of the waste slag field’s slope is rapidly reduced,reaching the unstable state of the slope directly,and the latter is more destructive to the slope of the waste slag yard than the former.The magnitude of the change in the safety factor at the peak acceleration time is greater than that at the non-peak acceleration time.After the ultimate destruction,the safety factor changes with the fluctuation of the seismic wave acceleration.With the duration of seismic wave loading,the stability of the waste slag field tends to decrease.When the acceleration of seismic wave decreases to 0,the slope stability coefficient also tends to be constant.(5)Comparing the pre-optimized and the optimized waste slag field,the total slag amount remains the same,the land area can be reduced by 2758m2,the land area can be saved by 20.05%,and the land occupation area can be saved by 20.05%,if the original design floor space is unchanged,slag is piled up,the volume of the body can increase by 96,313 m3 with an increase rate of 13.57%.In the situation of nature,the safety of the slag field was improved by 4.06% after the optimization,and the safety of the slag field was increased by 28.6% under the condition of strong rain and heavy rain with 96h2.5mm/h,and the safety of the optimized slag field was increased by 4.7%.under thecondition of heavy rain,strong 40mm/h rain and continuous rainfall 4h,and,in extreme conditions,that is,firstly rainfall make the slope of the waste slag field reach saturation,and then earthquake occurs,the slope stability of the waste slag field after optimization is increased by 12.8%,and the waste slag field can reach a stable state basically.