宽级配弱固结土入渗及抗冲性对泥石流起动的影响
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国家自然科学基金项目“黏性泥石流沟床大幅度冲淤机理研究”(40971014);国家重点基础科学(973)研究项目“中国西部特大山洪泥石流形成机理与风险控制”(2011CB409902)


Effect of Infiltration and Anti-scourability of Mixed-grain-sized, Unconsolidated Soil on Debris Flow Initiation
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    摘要:

    震后诱发的大量崩塌滑坡松散物质,为泥石流的形成提供了极为丰富的固体物源,使得震后灾区泥石流一直处于群发、频发状态.这些松散土体由于扰动强度大,属于宽级配弱固结土体.在降雨作用下产生的水土耦合作用促使土体结构破坏,从而起动形成泥石流.通过对该种土体进行的入渗和抗冲试验的结果表明:(1)震后的宽级配弱固结土体的入渗强度是蒋家沟流域类似土体的1.5~6.0倍,直接导致了在降雨入渗作用下土体内部细颗粒被侵蚀搬运,并伴随着土体结构的破坏.(2)抗冲性显示了由于其弱固结特性,土体的抗冲性系数很小,在表面径流作用下,土体易崩解而被径流冲刷流失,增强了径流侵蚀能力.(3)震后降雨与特殊土体的耦合作用促使了灾区泥石流一直处于群发、频发状态,并将持续到土体恢复至震前状态,在此期间灾区的泥石流激发雨量也会随之变化.

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    Numerous landslides occurred owing to the Wenchuan earthquake, leading to the accumulation of loose solid materials on valleys and slopes that trigger debris flows. The debris flows induced by rainfalls oc-curred frequently due to the presence of the wide-grade-unconsolidated soil. The loose soils that were dis-turbed intensively during the earthquake and mixed with rainfall after the earthquake became highly unstable and resulted in debris flows easily under storm rainfalls. It was found through the experiments of the infiltra-tion and erosion that the rate of the infiltration of the post-earthquake, mixed-grain-sized, unconsolidated soil was 1.5~6.0 times those of the similar soils in Jiangjia Gully, and resulting in the loss of finer particles in the soil and eventually the destruction of soil structure. The results of anti-scourability experiments show that the anti-scourability of the unconsolidated soil was weak due to the intensive disturbance it experienced, resulting in disintegration of soil agreggates and the soil was then eroded and transported away by surface runoff. The frequent occurrence of debris flows might be attributed to the strong rainfall along with the un-consolidated state of the soil. This phenomenon could keep occurring until the soil structure return to the o-riginal status before the earthquake. The critical rainfall for debris flow initiation may also change during this period.

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庄建琦,游勇,陈晓清,裴来政.宽级配弱固结土入渗及抗冲性对泥石流起动的影响[J].水土保持通报,2012,(4):43-47

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  • 收稿日期:2011-04-05
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  • 在线发布日期: 2014-11-25
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