Influence of hydraulic-mechanical coupling and dry-wet cycle effect on surficial layer stability of residual soil slopes
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摘要:
降雨入渗过程中，土体吸力降低，体积明显改变。天然浅层土体长期受到季节性气候变化的影响，因此，开展水-力耦合及干湿交替对浅层残积土坡稳定性影响的数值分析，分析浅层土坡孔隙水压力、湿润锋及安全系数的时空演变规律，并对水-力耦合及干湿交替条件下的浅层土坡失稳破坏机制进行探讨显得尤为必要。研究结果表明：随着干湿循环次数的增加，水-力耦合分析下孔隙水压力以及湿润锋的迁移速度增加更快，边坡也更易失稳破坏；干湿交替初期，雨水入渗易引起地下水位上升，边坡可因正孔隙水压力的增加而失稳；干湿交替后期，湿润锋的快速推进加剧基质吸力迅速丧失及土体强度下降，边坡安全系数显著降低，发生失稳破坏的时间缩短。因此，可将湿润锋处的安全系数(局部最小值)作为控制边坡长期稳定性的临界值。
Abstract:During rainfall infiltration, soil suction decreased and volume changed significantly. Since the natural shallow soil was under the influence of seasonal climate changes for a long time, numerical analysis of the influence of hydraulic-mechanical coupling and dry-wet alternation on the stability of shallow residual soil slopes was carried out. The temporal and spatial evolution law of pore water pressure, wetting front and safety factor of shallow soil slopes were analyzed deeply, then, the failure mechanisms of soil slopes under hydraulic-mechanical coupling and alternating dry-wet conditions were further discussed. Results show that with the increase of dry-wet cycles, the migration velocity of wetting front and pore water pressure increased more quickly, and the slope was more unstable under hydro-mechanical coupling analysis. At the early stage of the dry-wet cycle, the infiltration of rainwater would easily cause the groundwater level to rise, and the slope might lose its stability due to the increase of positive pore water pressure. In the later stage of dry-wet cycle, the rapid advance of wetting front accelerated the rapid loss of matrix suction and the decrease of soil strength, the safety factor of slope was significantly reduced and the time of failure was shorter. Therefore, the safety factor (local minimum) at the wetting front could be used as the critical value to control the long-term stability of the slope.
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Key words:
- hydro-mechanical coupling /
- dry-wet cycle /
- residual soil slope /
- wetting front /
- safety factor /
- long-term stability
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表 1 数值计算所需参数取值
Table 1. Parameter value required for numerical calculation
性质 单位 数值 重度γ kN·m−3 18.5 杨氏模量 Esat kPa 2300 泊松比 μ − 0.4 有效强度指标 c' kPa 16 φ' ° 15 饱和渗透系数 ksat m·d−1 1.8×10−3 饱和体积含水率 θs − 0.51 残余体积含水率 θr − 0.15 
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