南水北调中线工程膨胀土渠坡稳定问题及对策

On slope stability of expansive soil canal of Middle Route Project of S-N Water Transfer and countermeasures

重点分析了非饱和膨胀土边坡失稳的原因 ,在降雨入渗的条件下 ,膨胀土常发生浅层滑动 ,这种滑动与通常饱和土的边坡失稳的原因是不同的。为了弄清膨胀土边坡滑动 (主要是浅层滑动 )的机理 ,在南水北调中线工程渠道附近进行了大型人工降雨试验 ,得到了有意义的结论。由此认为 ,采用通常饱和土边坡稳定分析方法来校核非饱和膨胀土边坡的稳定 ,对于深部过于保守 ,而对浅部则不够安全 ,因此是不合适的。

The failure mechanism of unsaturated expansive soil slope is analyzed emphatically. Under the condition of rainfall infiltration, shallow layer expansive soil slide occurs frequently and this kind of slide mechanism is different from that of saturated soil. In order to make the mechanism of expansive soil slide clear, a large scale of artificial rainfall experiment was carried out near the canal area of Middle Route Project of S-N Water Transfer and meaningful conclusion was obtained. It was concluded that the stability verification results of unsaturated expansive soil slope by the method usually used for the stability analysis of saturated expansive soil is over safe for deep layer but insufficient for shallow layer, therefore, it is not applicable. According to the failure mechanism of unsaturated expansive soil slope, the countermeasures to prevent shallow layer soil slide are suggested.