| Transportation,minerals,water conservancy projects and other projects will generate a large amount of artificial waste slag during the construction process.If these waste slags are not handled properly,they will be directly piled up on-site,which will damage the surface vegetation and the bad environment of the project area,and threaten the safety of the site construction.It may even cause instability.In addition,in order to pursue less land occupation and higher economic benefits,people have continuously increased the pile height and slope angle of the waste slag yard(soil dump),so that the maximum accumulation of the waste slag yard has become the highest goal.Each increase in the volume of the waste slag yard will generate tens of millions or even billions of dollars.However,as the volume of the waste slag yard increases,the slope of the waste slag body becomes more and more steep,causing the accumulation slope to be unstable.Collapse,landslide and other geological disasters.In this paper,the waste slag yard of the No.26 contract section of Huali Expressway in Yunnan Province is taken as the research object.Since the waste slag yard has not reached the final pile shape and has been in operation,the distribution rule of on-site excavation trenches to measure the particle gradation cannot be achieved,and it is completed on site.After testing the in-situ density and natural moisture content,the disturbed soil in the waste slag yard will be sampled,packaged,and transported back to the laboratory for indoor slag discharge simulation test.Stone distribution along the slope in vertical and horizontal directions.Then,the large-scale direct shear test is used to study the change law of the shear strength parameters under different rock content conditions,and the relationship between the shear strength parameters and the rock content and the shear strength parameters in each area of the slag yard are obtained.Finally,Hypermesh software was used to perform three-dimensional modeling of the waste slag field entity.Four calculation models were established,and flac3 d was imported.The determined mechanical parameters were substituted into different calculation models for stability analysis and calculation.The displacement field,strain field,and safety factor were analyzed.Wait.The main conclusions of this article are as follows:(1)The results of the dumping test in the simulated waste dump show that the final stacking shape of the waste dump is a “inverted triangle” with the thickness up and the thickness down,which is consistent with the shape of the waste dump after several times of dumping.(2)The slag particle size has certain regularity along the horizontal and vertical direction of the slope.The slope is divided into 5 layers from high to low along the vertical height of the slope.The content of soil particles(particle size < 5mm)decreases with the decrease of the slope height.The content of medium stone particles(5mm < particle size < 20mm)increases first and then decreases with the decrease of the slope height.The content of coarse stone particles(20mm < particle size < 60mm)and the content of stone(particle size > 5mm)increase with the decrease of the slope height.Along the horizontal direction from the slope to the slope,the content of soil particles increases gradually,and the fourth layer presents the opposite law;the content of medium stone particles increases gradually;the content of coarse stone particles decreases gradually;the content of stone decreases gradually,and the fourth layer presents the opposite law;the content of each particle group along the horizontal direction changes little as a whole.(3)The shear strength parameters of the sample change with the stone content,and the internal friction angle of the sample increases nonlinearly with the stone content.In the range of low stone content(stone content < 20%),the increase of internal friction angle is smaller with the increase of stone content;in the range of medium stone content(20% < stone content ? 80%),the increase of internal friction angle is faster with the increase of stone content;in the range of high stone content(stone content > 80%),the increase of internal friction angle is smaller;the cohesion increases first and then decreases with the increase of stone content It reaches the peak value when the content of rock is 40%.(4)The displacement value,safety factor value and shear strain increment of the four calculation models are different;the total displacement of the slope decreases with the refinement of the calculation model layers and zones;the safety factor value of the layer and zone models is larger than that of the homogeneous model,in which the safety factor number of the five layer model is the largest and the slope state is the most stable;the calculation result ratio of the safety factor value in the three-dimensional strength reduction method The calculation result of the two-dimensional limit equilibrium method is small;in the displacement profile along the characteristic point x-z direction,the position of the maximum displacement value is consistent with the position of the maximum displacement of the total displacement of the slope,and the range of the maximum displacement value of the slope decreases with the refinement of the calculation model layers and zones;in the shear strain incremental profile along the characteristic point x-z direction,it can be seen that the maximum shear strain area is divided with the calculation model The thinning of layers and zones is gradually reduced.The displacement and shear strain increment of each characteristic point in Y-Z direction are not consistent,which shows that the zoning and stratification model have obvious influence on the stability analysis results of the waste disposal site.(5)Under the earthquake condition,the displacement,shear strain increment and safety factor of the waste disposal site are consistent with those under the natural condition;the total displacement of each calculation model under the earthquake condition is 213.27 mm for model I,205.20 mm for model II,176.46 mm for model III and 136.96 mm for model IV,which are 102.29%,114.58%,109.62% and 133.16% higher than those under the natural condition;The safety factors calculated by the limit equilibrium method are 1.30 for model I,1.32 for model II,1.42 for model III and 1.36 for model IV,which are 9.27%,9.59%,7.79% and 9.33% lower than those under natural conditions respectively;the safety factors calculated by the strength reduction method are 1.04 for model I,1.06 for model II,1.12 for model III and 1.10 for model IV,which are more natural than those under natural conditions Under the working condition,the safety factors are reduced by 15.45%,15.87%,13.85% and 14.06% respectively. |
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