Optimization design of high loess slope based on combination of wide and narrow platform：A case study of an industrial square in Zichang City

The construction of a coal mine industrial square in a mountainous area or hilly area will face the problem of high slopes. The unreasonable high slope design causes serious waste of land resources, environmental damage and an increase in investment, and also brings huge potential safety risks to the infrastructure. Based on this, with a high slope in a coal mine industrial square in Zichang City of Shaanxi Province as an example, the field investigation, theoretical analysis and numerical simulation were used to investigate the influence of different numbers, positions and widths of wide platforms on the stress, strain field and stability coefficient of high slopes in view of the erosion resistance and the overall stability of the slope. Combined with the excavation amount of the model, the optimal slope shape that meet the stability requirements and had the least excavation amount was obtained. The results show that the optimal single slope ratio of high slopes of powdered loess in northern Shaanxi is 1∶0.75, and the slope height is 5-6 m. The wide platform could change the position of the potential slip surface. When the wide platform is located at the toe or top of the slope, the distribution of potential slip surfaces is bounded by the position of the wide platform, and is distributed on the slope above or below the wide platform. When the wide platform of great width is continuously distributed, the high slope can be regarded as two independent slopes for analysis and calculation. The optimal slope shape of the high slope is featured by a 30 m high slope with a single slope height of 5 m and a slope ratio of 1∶0.75, a narrow platform of 3 m wide, and two wide platforms with a width of 10 m at location ③⑤; a 50 m high slope with a single slope height of 5 m and a slope ratio of 1∶0.75, a narrow platform of 3 m wide, and four wide platforms with a width of 14 m at location ③⑤⑧⑨. The optimal combination of wide and narrow platforms provides a theoretical basis and practical guidance for the design and protection of high slopes of powdered loess in northern Shaanxi.