泥石流和牵引式滑坡灾害---Debris and flowslide

1 引言

第八届国际泥石流灾害缓解会议(8th International Conference on Debris Flow Hazard Mitigation)将于2023年6月26日~29日在意大利都灵理工学院(Turin Polytechnic)召开，会议将涵盖与泥石流有关的所有方面，从了解其力学行为到缓解和风险评估过程。

              相关文章，在仿真秀官网搜索：

• 高位高速滑坡泥石流复合型灾害案例---6人失联
  

• 从岩土工程视角看缅甸玉矿滑坡造成的重大伤亡
  

2 主题

(1) Debris flow triggering

[1] Debris flow triggering by impulsive loading: mechanical modelling and case studies.

[2] Estimation of debris flow triggering rainfall: influence of rain gauge density and interpolation methods.

(2) Debris flow entrainment and motion

[1] MPM simulations of debris flow entrainment, modelling boulders explicitly

(a) 材料点法(MPM)隐式接触技术的发展

(b) Material Point Method in Computational Geomechanics

(c) Material Point Method Simulations of Cone Penetration and CPT Interpretation

[2] Positive feedback and momentum growth during debrisflow entrainment of wet bed sediment 

(3) Debris-flow deposition and fan morphology

[1] Size of a debris flow deposition: model experiment approach. 

(4) Hydrology and debris flows

(5) Laboratory and numerical modeling

(6) Field investigation

(7) Remote sensing and monitoring techniques

(8) Assessment of debris-flow susceptibility, hazard and risk

(9) Application of mitigation technologies

(10) Best practice guidelines

(11) Forensic debris flow studies

(12) Emergency management

(13) Integration of multidisciplinary viewpoints

(14) Risk management by local governments and legislation

3 Flowslide

与debris flows相近的一种灾害是flowslide(high-velocity earth movement; mudflow)，[flowslide.txt]，flowslide的一种滑坡型式是倒退式滑坡，有位同学提出这种型式应该称之为牵引式滑坡。

Mount Polley尾矿坝的flowslide

倒退式滑坡(retrogressive landslides)一般在边坡的底部开始出现滑动，使得后面的剪应力不断增加，从而诱发新的滑动，然后滑坡面一直向后移动。在加拿大东部，主要是魁北克省和安大略省，粘土的沉积物通常呈现为"灵敏性粘土(sensitive clays)"，当粘土沉积物足够灵敏度时，便会发生高度倒退式滑坡(highly retrogressive landslides)。在这些滑坡中观察到的倒退距离可达几百米，甚至偶尔会超过1公里。因此，这种地质灾害现象可能对人群和基础设施构成重大风险，尤其是魁北克省的某些地区特别容易受到这种危险的影响。

倒退式滑坡与粘土的灵敏度密切相关。灵敏度定义为在相同的含水量下，未受扰动状态下的不排水强度与重塑状态下的不排水强度的比值(Craig 2012), 如果改变了粘土颗粒的结构，则粘土将失去大部分的强度。灵敏度St大于4的粘土称之为灵敏性粘土。Quick clays(快速粘土)的灵敏度值没有尽头，但很少有大于100的。灵敏度与液性指数(liquidity index)【基于液限和塑限的经验关系式总结】呈线性关系(Bjernum 1960), 如下图所示。

[1] Flowslides in sensitive clays of eastern Canada

[2] Back-analyzing the triggering of a retrogressive loess flowslide 

[3] Analysis of a retrogressive landslide in glaciolacustrine varved clay. 

[4] Retrogressive slope failure in glaciolacustrine clays: Sauga landslide, western Estonia. 

[5] Retrogressive slope failures at Beaver Creek, south of Saskatoon, Saskatchewan, Canada.

[6] Centrifuge model test on the retrogressive landslide subjected to reservoir water level fluctuation. 

[7] Delayed failure of quarry slopes in stiff clays: The case of the Lucera landslide.

[8] Modelling of flowslides and debris avalanches in natural and engineered slopes: a review

除了在高灵敏度的粘土地区容易发生倒退式滑坡，岩体边坡由于风化以及坡脚开挖，也有可能发生倒退式滑坡，例如位于加拿大不列颠哥伦比亚省的Checkerboard Creek slope，边坡有60米深的风化带，在季节性温度变化的影响下冻结和融化过程导致岩石以每年13mm的速度移动，为了防止大规模的倒退式滑坡，使用了10cm厚的喷射混凝土和间距8m的锚索进行了支护[Stability of a Rock Slope Susceptible to Seasonal Movements]。