Research on the slope stability of seasonally running canals
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摘要: 由于渠道季节性通、停水引起的干湿循环过程显著降低了渠基膨胀土的强度,进而影响膨胀土渠道的稳定性。以北疆典型膨胀土渠道为例,通过直接剪切试验对不同干湿循环次数下渠基膨胀土的力学特性和表面裂隙发育特征进行研究,在此基础上对水位骤降期间渠道边坡的稳定性进行了数值计算。结果表明:随着干湿循环次数的增加,试样表面的裂缝发育不断加剧,并在一定循环次数后逐渐趋于稳定;试样的黏聚力发生较为显著的衰减,而内摩擦角值则呈小幅度波动式衰减的趋势。在5次干湿循环后,试样的黏聚力和内摩擦角分别降低了36.5%~48.2%和10.8%~26.1%。此外,随着运行年份(干湿循环次数)的增加,渠道边坡稳定性呈逐年下降趋势;排水时间对于渠道边坡的稳定性同样影响显著,排水时间越长,渠道边坡稳定性越高。建议该膨胀土渠道边坡排水时间不少于12 d,诊断、维修间隔不长于5年。研究成果对北疆供水工程建设与维护具有一定参考价值。Abstract: The wetting-drying process caused by seasonally running of canals can significantly reduce the strength of expansive soil below the canal structure, thereby affecting the stability of expansive soil canal. Taking the typical expansive soil canal in North Xinjiang as an example, the mechanical properties and the development characteristics of surface cracks of expansive soil below the canal structure were studied in the direct shear laboratory with wetting-drying cycles. On this basis, the numerical calculation of the canal slope stability during the water-level falling period was carried out. The results show that with the increase of wet-dry cycles, the cracks on the surface of the tested soil samples are growing and gradually stabilized after a certain number of cycles. The cohesion of the samples decreases significantly, while the internal friction angle decreases in a small fluctuating manner. After five wetting-drying cycles, the cohesion and internal friction angle decreased by 36.5%~48.2% and 26.1%~10.8%, respectively. Additionally, with the increase of running years (wetting-drying cycles), the canal slope stability decreased year by year. The drainage time also has a significant effect on the canal slope stability. The longer the drainage time is, the higher the canal slope stability is. It is suggested that the drainage time of the expansive soil canal slope would better be more than 12 days, and the interval between diagnosis and maintenance would better be no longer than 5 years. The research results have a certain reference value for the construction and maintenance of water supply projects in Xinjiang.
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Key words:
- wetting-drying cycle /
- expansive soil /
- crack /
- strength parameters /
- slope stability
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表 1 膨胀土渠坡安全系数及稳定性状态
Table 1. Safety factor and stability state of expansive soil canal slope
排水时间/d 未运行渠道 运行第1年 运行第2年 运行第3年 运行第4年 运行第5年 8 1.52(稳定) 1.44(稳定) 1.29(基本稳定) 1.22(基本稳定) 1.15(基本稳定) 1.04(欠稳定) 12 1.61(稳定) 1.52(稳定) 1.37(稳定) 1.30(基本稳定) 1.22(基本稳定) 1.10(基本稳定) 16 1.69(稳定) 1.59(稳定) 1.43(稳定) 1.35(稳定) 1.27(基本稳定) 1.15(基本稳定) 20 1.74(稳定) 1.63(稳定) 1.48(稳定) 1.41(稳定) 1.29(基本稳定) 1.19(基本稳定) -
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