ANALYSIS ON VARIATIONS OF DISPLACEMENT RATES UNDER INFLUENCES OF RAINFALL AND EXCAVATION—TAKING RIGHT BANK SLOPE OF GAOBEI KEY WATER CONTROL PROJECT AS CASE STUDY
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摘要: 对临时边坡坡脚下挖和逐级浇筑砼挡墙支护的水利枢纽尾水渠工程而言,如何在雨季利用强降雨间隙高强度开挖基坑后浇筑回填即起支挡加固作用而不至引发大规模滑动破坏,是此类工程中优先考虑的问题。工程实践中采用信息化施工成功与否很大程度上依赖于滑坡变形过程及位移矢量关系分析及精细施工组织。本文以韩江高陂水利枢纽右岸边坡为例,在工程地质条件分析基础上,通过对尾水渠挡墙基坑开挖中边坡变形监测数据分析,得到多个监测点矢量时空变化关系,验证了边坡变形过程中的顺时针压扭式固结排水破坏机制。结合降水资料分析,得到边坡变形与降水和开挖的对应关系。结果表明,边坡日均位移速率v与日均降水量p之间的统计关系式为v=103.45ln(p)-82.821,非强降雨时段主要由坡脚开挖引发的平均位移速率可达200 mm ·d-1。上述破坏模式和监测分析结果为尾水库挡墙信息化施工提供了依据,从而为该工程在雨季达到施工安全提供了保证。Abstract: How to use the time schedule in case of heavy precipitation and undertaking intensive excavation of the retaining wall pit, and then upward backfilling the slope as permanent reinforcement, is the priority countermeasure in the tail canal project. The information construction depends on the analysis results of the deformation process and displacement vector relationship, from the primary landslide and then transformed to the cut slope. This paper takes the right bank slope of Gaobei Key Water Control Project as an example. It analyzes the monitoring data during the excavation of retaining wall foundation pit of the tail canal, It obtains the three-dimensional vector space-time variation relations of 55 monitoring points. It reveals the mechanism of clockwise compression-shearing consolidation drainage failure in the process of slope deformation. It bases on the correlation of precipitation data and obtains the corresponding relationship between slope deformation and precipitation, as well as excavation in 4 different stages. The statistical relationship between the average daily displacement rate and the daily precipitation is approximately as v=103.45ln(p)-82.821. The paper infers that during the period of non-strong rainfall, the displacement rate caused by excavation of the slope foot reached 200mm ·d-1, which is the key parameter of information construction. The above failure modes and monitoring analysis results provide a basis for the information construction of retaining wall beside the tail canal. As a result the landslide was mitigated and cut slope was reinforced as designed in a rainy season.
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Key words:
- Gaobei key water control project /
- Landslide /
- Displacement vector /
- Precipitation /
- Retaining wall pit
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图 8 日降水分布直方图及累计降水量变化曲线
(降雨强度级别划分参考刘艳辉等(2016);(1)~(5)为降水高峰段编号)
Figure 8. Histogram of daily precipitation and variation curve of accumulated daily precipitation
表 1 4个不同时段位移速率与日均降水率关系表
Table 1. Relation of displacement rate and daily precipitation in 4 stages
监测点 时间段
月-日上、下午阶段(1)~(4) Y位移
速率
/mm·d-1平面位移
速率
/mm·d-1日均
降水率
/mm·d-1点6 03-13下~03-30上 1 265.54 297.85 33.42 点6 03-13下~03-30上 2 43.82 49.67 5.99 M9 05-04上~05-15上 3 250.64 283.88 5.05 T6 06-09上~06-14下 4 248.55 272.66 25.00 点5 03-13下~03-30上 2 32.48 36.40 5.99 点7 03-13下~03-30上 2 42.06 47.58 5.99 T9 06-09上~06-14下 4 289.27 309.29 25.00 -
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