| With the in-depth implementation of the "Belt and Road" strategy,the rapid economic development of the Loess Region has also brought many challenges.China is the country with the most widely distributed loess area in the world,mainly distributed in Shaanxi,Gansu,Ningxia and Shanxi in the northwest region.Due to its special characteristics such as macroporosity,vertical joint and collapsibility,loess has become the object of worldwide research.The gully in the loess area is vertical and horizontal,the topography changes greatly,the high and steep slopes are developed,and the stability is poor.Therefore,the evaluation of loess slope stability has always been a hot topic in the field of geotechnical engineering.How to design a safe,economical,and stable slope according to the characteristics of the loess slope and its environment is particularly important in practical engineering.This paper takes loess slopes with different geological structures that are common in nature as the research object,analyzes the three elements of single-stage slope height,single-stage slope ratio and platform width that control the stability of the slope,and designs orthogonal tests that meet the geological structure The reliability design theory and the finite element strength reduction method are used to optimize the design of the loess slope.This method has certain theoretical practical significance and engineering practical significance,simple calculation,and certain guidance and application value.The main research results obtained are as follows:(1)Taking the common loess slope in nature as the research object,the main factors affecting the stability of the slope are analyzed.Three types of loess slope models with different geological structures were established for the foundation of slope optimization design analysis.(2)Through the study of multiple sets of design schemes,it is shown that for a single 30 m high Malan loess slope,the safety factor of the straight slope decreases continuously as the slope height increases,and the slope ratio design should not be steeper than 1: 0.6 to ensure safety.When the design form is a polyline,the polyline node is 20 meters above the slope foot.When the upper slope ratio is 1: 0.6 and the lower slope ratio is 1: 1.2,it can meet the safety requirements and the minimum amount of excavation.When the design form is stepped,the single-stage slope ratio is 1: 0.75,the single-stage slope is 10 meters high,and the platform width is 6 meters.(3)For the 60-meter-high Malan-Lishi loess slope,three situations are considered in the design: 1.The upper Malan loess is designed to be linear,and the lower Lishi loess is designed to be stepped;2.The upper Malan loess is designed It has a large slope ratio and few steps,and the lower part of Lishi loess is designed with a small slope ratio and more steps;3.Malan Lishi and loess are considered together and designed as a whole.Orthogonal test method is still used for scheme design.The final result is: when the single-stage slope ratio of the upper Malan loess is 1: 0.6,a platform is set,the platform width is 4 meters,and the lower one-step slope ratio of the stone loess is 1: 1.2,the slope height is 7.5 meters,and the platform width is 3 meters.Requirements,the optimal solution with the smallest amount of excavation.(4)The analysis and research show that the 60-meter-high single-stone loess slope is the most reasonable stepped edge when the single-stage slope ratio is 1: 1.25,the single-stage slope is 15 meters high,and the platform width is 5 meters.Slope design form.(5)According to the analysis of variance of the calculation results,the sensitivity of the factors affecting the slope stability is different for slopes with different geological structures.Among them,the sensitivity of Malan-Lishi loess slope from high to low is as follows: platform width> single slope ratio> single grade high;in a single Lishi loess slope,the sensitivity is from high to low: single Slope ratio> single grade height> platform width. |
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