Optimization design of high loess slope based on combination of wide and narrow platform:A case study of an industrial square in Zichang City
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摘要: 山区或丘陵地带建设煤矿工业广场时将面临高边坡问题,不合理的高边坡设计严重浪费土地资源,造成环境破坏和投资增加,也为基础设施带来巨大安全隐患。基于此,以陕西省子长市某煤矿工业广场高边坡为例,借助现场调查、理论分析和数值模拟等手段,综合考虑边坡抗冲刷性和整体稳定性,探讨不同数量、位置和宽度的宽平台对高边坡的应力、应变场和稳定性系数的影响规律,结合模型的开挖量,选取满足稳定性要求且开挖量最少的最优坡形。结果显示:陕北地区粉黄土高边坡最优单坡坡率为1∶0.75,坡高5~6 m;宽平台能改变潜在滑移面位置,当宽平台位于坡脚或坡顶时,潜在滑移面分布以宽平台位置为界,分布于宽平台以上或以下边坡;当宽平台连续分布且宽度较大时,高边坡可视为2个独立边坡来分析计算;高边坡最优坡形为:30 m高边坡单坡高5 m、坡率1∶0.75,窄平台宽度3 m,布置2个宽平台、位置③⑤、宽度10 m;50 m高边坡单坡高5 m、坡率1∶0.75,窄平台宽度3 m,布置4个宽平台、位置③⑤⑧⑨、宽度14 m。宽窄平台优化组合方式可为陕北地区粉黄土高边坡设计和防护工作提供理论依据和实际指导。Abstract: 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.
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Key words:
- high slope /
- powdered loess /
- wide and narrow platform /
- optimization design /
- slope erosion resistance /
- stability
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表 1 高边坡野外调查情况
Table 1 Field survey of high slopes
序号 调查边坡 边坡概况 平台形式 破坏模式 防护措施 防护效果 边坡照片 1 禾草沟煤矿
自建高边坡总坡高30 m;
三级放坡;
平均坡率1∶0.5等距阶状坡 坡面冲刷+
滑塌分级削坡 较差 2 禾草沟煤
矿高边坡总坡高50 m;
十级放坡;
平均坡率1∶0.6等距阶状坡 坡面冲刷+
滑塌+剥落分级削坡 较差 3 车村煤矿
高边坡总坡高45 m;
十级放坡;
平均坡率1∶0.8等距阶状坡 局部坡面
冲刷+滑塌分级削坡+截排水+
护脚+绿化良好 4 志丹旅游专
线高边坡总坡高108 m;
十八级放坡;
平均坡率1∶0.6宽窄平台坡 坡面冲刷 分级削坡 良好 表 2 研究区土体基本物理性质
Table 2 Basic physical properties of the soils in the study area
土体 含水率ω/% 饱和含水率ωsat/% 相对密度 容重γ/(kN·m−3) 塑性指数Ip/% 液性指数IL/% 渗透系数K/(cm·s−1) 弹性模量E/MPa 泊松比υ 黏聚力c/kPa 内摩擦角φ/(°) 粉黄土 9.8 32.6 2.69 14.8 8.8 –1.10 4.58×10−5 35 0.3 20.20 24.48 表 3 坡率设计参数取值
Table 3 Design parameters of the slope ratio
参数 粉黄土取值 单宽降雨强度p/(m·s–1) 9.3×10−7 坡面入渗率i/(cm·min–1) 3.492×10−3 坡面粗糙度μ 0.05 土颗粒粒径D/mm 0.07 土颗粒的饱和容重γs/(kN·m–3) 26.9 水密度ρ/(g·cm–3) 1 水容重γw/(kN·m–3) 10 表 4 粉黄土坡率临界取值
Table 4 Critical values of the slope ratio of the powdered loess
坡长/m 临界坡率 坡高/m 4.5 1∶0.63 3.81 5.0 1∶0.66 4.17 5.5 1∶0.69 4.53 6.0 1∶0.72 4.87 6.5 1∶0.75 5.20 7.0 1∶0.78 5.52 7.5 1∶0.80 5.86 8.0 1∶0.84 6.13 8.5 1∶0.87 6.41 9.0 1∶0.90 6.69 9.5 1∶0.93 6.96 10.0 1∶0.96 7.21 10.5 1∶0.99 7.46 11.0 1∶1.03 7.66 11.5 1∶1.06 7.89 12.0 1∶1.10 8.07 12.5 1∶1.13 8.28 -
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