摘要
Study on the grain size distribution characteristics and the frictional strength behavior of the slide deposits are helpful to disclose the landslide runout process and understand the mechanism of a long runout landslide. We performed grain size distribution analysis on samples collected from Chenjiaba landslide induced by Wenchuan earthquake. The grain size distribution of samples from the landslide sections quantitatively depicts a gradual coarsening upward grading from shear zone to the top section. Then a multistage-multiphase ring shearing approach was used to determine a comparative shear strength behavior of samples from each landslide section. In this method, a sample was sheared continuously for large displacement and fast rate on different normal stress conditions. The multiphase shear mode with a maximum of 105 mm/min rate has allowed observing the qualitative change and patterns of the frictional resistance behaviors of soils under different normal stresses. The results of coefficient of friction values under multiphase shear mode have shown substantial post peak shear weakening behaviors after large shear displacement that can be narrated with long runout processes. The shear strength test results indicate that the shear zone samples have developed higher friction angle values compared to overlying section samples, on the last phase of shear process, which may be very important to understand the braking mechanism of a long runout landslide.
Study on the grain size distribution characteristics and the frictional strength behavior of the slide deposits are helpful to disclose the landslide runout process and understand the mechanism of a long runout landslide. We performed grain size distribution analysis on samples collected from Chenjiaba landslide induced by Wenchuan earthquake. The grain size distribution of samples from the landslide sections quantitatively depicts a gradual coarsening upward grading from shear zone to the top section. Then a multistage-multiphase ring shearing approach was used to determine a comparative shear strength behavior of samples from each landslide section. In this method, a sample was sheared continuously for large displacement and fast rate on different normal stress conditions. The multiphase shear mode with a maximum of 105 mm/min rate has allowed observing the qualitative change and patterns of the frictional resistance behaviors of soils under different normal stresses. The results of coefficient of friction values under multiphase shear mode have shown substantial post peak shear weakening behaviors after large shear displacement that can be narrated with long runout processes. The shear strength test results indicate that the shear zone samples have developed higher friction angle values compared to overlying section samples, on the last phase of shear process, which may be very important to understand the braking mechanism of a long runout landslide.
引文
ASTM-D2487-11(2011)Standard practice for classification of soils for engineering purposes(Unified Soil Classification System).ASTM International,West Conshohocken,PA.Available online at:https://standards.globalspec.com/std/1378912/astm-d2487(Accessed on 2019-03-20)
ASTM-D6467-13(2013)Standard Test Method for Torsional Ring Shear Test to Determine Drained Residual Shear Strength of Cohesive Soils.ASTM International,West Conshohocken,PA.Available online at:https://tajhizkala.ir/doc/ASTM/D6467-13.pdf(Accessed on 2017-06-10)
Bhat DR,Bhandary NP,Yatabe R,et al.(2013)Strength recovery from residual-state of shear on soils.Indian Geotechnical Journal 44(1):94-100.https://doi.org/10.1007/s40098-013-0066-2
Bishop AW,Green GE,Garga VK,et al.(1971).A new ring shear apparatus and its application to the measurement of residual strength.Géotechnique 21(4):273-328.https://doi.org/10.1680/geot.1971.21.4.273
Bromhead E,(1979).A simple ring shear apparatus.Ground Engineering 12(5).
Davies TR,McSaveney MJ(2011)Rock-avalanche size and runout-implications for landslide dams.Springer-Verlag Berlin Heidelberg 133:441-462.https://doi.org/10.1007/978-3-642-04764-0_17
Deng Q,Chen G,Zhu A(2011)Discussion of rupture mechanisms on the seismogenic fault of the 2008 Ms 8.0Wenchuan earthquake.Science China Earth Sciences 54(9):1360-1377.
Du Y,Xie F,Wang Z(2012)Wenchuan earthquake surface fault rupture and disaster:a lesson on seismic hazard assessment and mitigation.International Journal of Geophysics 2012:1-6.
Dunning SA,Armitage PJ(2011)The grain size distribution of rock-avalanche deposits:implications for natural dam stability.Springer Berlin Heidelberg 133:479-498.https://doi.org/10.1007/978-3-642-04764-0_19
Eid HT,Amarasinghe RS,Rabie KH,ea al.(2015)Residual shear strength of fine grained soils and soil-solid interfaces at low effective normal stresses.Canadian Geotechnical Journal52(2):198-210.https://doi.org/10.1139/cgj-2014-0019
Fan X,Scaringi G,Xu Q,et al.(2018)Coseismic landslides triggered by the 8th august 2017 Ms 7.0 Jiuzhaigou earthquake(Sichuan,China):factors controlling their spatial distribution and implications for the seismogenic blind fault identification.Landslides,Springer-Verlag Germany,part of Springer Nature.https://doi.org/10.1007/s10346-018-0960-x
Habibbeygi F,Nikraz H(2018)Effect of shear rate on the residual shear strength of pre-sheared clays.Cogent Geoscience 4:1.https://doi.org/10.1080/23312041.2018.1453989
Hoyos LR,Velosa CL,Puppala AJ(2014)Residual shear strength of unsaturated soils via suction-controlled ring shear testing.Engineering Geology 172:1-11.https://doi.org/10.1016/j.enggeo.2014.01.001
Huang T,Ding M,She T,et al.(2017)Numerical simulation of a high-speed landslide in Chenjiaba,Beichuan,China.Journal of Mountain Science 14(11):2137-2149.https://doi.org/10.1007/s11629-017-4516-7
Huy LD,Sassa K,Fukuoka H,et al.(2018)Initiation mechanism of rapid and long run-out landslide and simulation of Hiroshima landslide disasters using the integrated simulation model(LS-RAPID).Landslide dynamics:ISDR-ICL landslide,Springer International publishing.https://doi.org/10/1007/978-3-319-57777-7_6
Igwe O,Sassa K,Wang F(2006)The influence of grading on the shear strength of loose sands in stress-controlled ring shear tests.Landslides,Springer-Verlag 4:43-51.https://doi.org/10.1007/s10346-006-0051-2
Jan Novotny JK(2014)Grain size distribution of soils within the cordillera Blanca,Peru:an indicator of basic mechanical properties for slope stability evaluation.Journal of Mountain Science 11(3).https://doi.org/10.1007/s11629-013-2836-9
Li D,Yin K,Glade T,et al.(2017)Effect of over-consolidation and shear rate on the residual strength of soils of silty sand in the Three Gorges Reservoir.Sci Rep 7(1):5503.https://doi.org/10.1038/s41598-017-05749-4
Lian B,Peng J,Wang X,et al.(2018)Influence of shearing rate on the residual strength characteristic of three landslides soils in loess area.Natural Hazards and Earth System Sciences Discussions 1-24.
Nam S,Gutierrez M,Diplas P,et al.(2011)Determination of the shear strength of unsaturated soils using the multistage direct shear test.Engineering Geology 122(4):272-280.https://doi.org/10.1016/j.enggeo.2011.06.003
Parez S,Aharonov E(2015)Long runout landslides:a solution from granular mechanics.Frontiers in Physics 3(80).https://doi.org/10.3389/fphy.2015.00080
Qi S,Xu Q,Lan H,et al.(2011)Spatial distribution analysis of landslides triggered by 2008.5.12 Wenchuan Earthquake,China.Engineering Geology 116:95-108.https://doi.org/10.1016/j.enggeo.2010.07.011
Radjai F,Az′ema E(2009)Shear strength of granular materials.European Journal of Environmental and Civil Engineering,Ed.Lavoisier 13(2):203-218.https://doi.org/10.3166/ejece.13.
Roback K,Clark MK,West AJ,et al.(2018)The size,distribution,and mobility of landslides caused by the 2015Mw 7.8 Gorkha earthquake,Nepal.Geomorphology,Elsevier301:121-138.https://doi.org/10.1016/j.geomorph.2017.01.030
Robinson TR,Rosser NJ,Densmore AL,et al.(2017)Rapid post-earthquake modelling of coseismic landslide intensity and distribution for emergency response decision support.Natural Hazards Earth System Sciences 17:1521-1540.https://doi.org/10.5194/nhess-17-1521-2017
Roy S,Bhalla SK(2017)Role of geotechnical properties of soil on civil engineering structures.Resources and Environment7(4):103-109.https://doi.org/10.5923/j.re.20170704.03
Santamarina JC,Cho GC(2004)Soil behaviour:the role of particle shape.Proc.Skempton Conf.,London.https://doi.org/10.1680/aigev1.32644.0035
Sassa K,Nagai O,Solidum R,et al.(2010)An integrated model simulating the initiation and motion of earthquake and rain induced rapid landslides and its application to the 2006 Leyte landslide.Landslides 7(3):219-236.https://doi.org/10.1007/s10346-010-0230-z
Scaringi G,Hu W,Xu Q,et al.(2018)Shear-rate-dependent behavior of clayey bimaterial interfaces at landslide stress levels.Geophysical Research Letters 45(2):766-777.https://doi.org/10.1002/2017GL076214
Schaeffer DG,Iverson RM(2008)Steady and intermittent slipping in a model of landslide motion regulated by porepressure feedback.SIAM Journal on Applied Mathematics69(3):769-786.https://doi.org/10.1137/07070704X
Stark TD,Contreras IA(1996)Constant volume ring shear apparatus.Geotechnical Testing Journal 19(1):3-11.https://doi.org/10.1520/GTJ11402J
Tang C,VanWesten CJ,Tanyas H,et al.(2016)Analysing postearthquake landslide activity using multi-temporal landslide inventories near the epicentral area of the 2008 Wenchuan earthquake.Natural Hazards Earth System Sciences,EGU 16:2641-2655.https://doi.org/10.5194/nhess-16-2641-2016
Tang HM,Liu X,Hu XL,et al.(2015)Evaluation of landslide mechanisms characterized by high-speed mass ejection and long-run-out based on events following the Wenchuan earthquakes.Engineering Geology 194:12-24.https://doi.org/10.1016/j.enggeo.2015.01.004
Tika TE,Vaughan PR,Lemos LJ,(1996)Fast shearing of preexisting shear zone in soil.Geotechnique 46(2):197-233.https://doi.org/10.1002/2016JB013241
Usuki N,Mizuyama T(2011)Soil properties and fluidity of longtravelling landslides.Italian Journal of Engineering Geology and Environment-5th International Conference on DebrisFlow Hazards Mitigation:Mechanics,Prediction and Assessment.https://doi.org/10.4408/IJEGE.2011-03.B-086
Wang F,Sassa K(2000)Relationship between grain crushing and excess pore pressure generation by sandy soils in ring shear tests.Journal of natural disaster science 22(2):87-96.https://doi.org/10.2328/jnds.22.87
Wang F,Sun P,Highland L,et al.(2014)Key factors influencing the mechanism of rapid and long runout landslides triggered by the 2008 Wenchuan earthquake,China.Geoenvironmental Disasters;Springer open access 1(1).https://doi.org/10.1186/s40677-014-0001-6
Wang G,Suemine A,Schulz WH(2010)Shear-rate-dependent strength control on the dynamics of rainfall-triggered landslides,Tokushima Prefecture,Japan.Earth Surface Processes and Landforms,wiley intersciences.https://doi.org/10.1002/esp.1937
Wu S,Wang T,Shi L,et al.(2010)Catastrophic landslides triggered by the 2008 Wenchuan earthquakes.China.Engineering Geology 18(2):145-159.https://doi.org/1004-9665/2010/18(2)-0145-15.
Xing A,Wang G,Li B,et al(2015)Long-runout mechanism and landsliding behaviour of large catastrophic landslide triggered by heavy rainfall in Guanling,Guizhou,China.Canadian Geotechnical Journal 52(7):971-981.https://doi.org/10.1007/s10346-015-0617-y
Xu C,Xu X,Dai F,et al.(2012)Comparison of different models for susceptibility mapping of earthquake triggered landslides related with the 2008 Wenchuan earthquake in China.Computers&Geosciences 46:317-329.https://doi.org/10.1016/j.cageo.2012.01.002
Xu C,Xu X,Yao X,et al(2014)Three(nearly)complete inventories of landslides triggered by the May 12,2008Wenchuan Mw 7.9 earthquake of China and their spatial distribution statistical analysis.Landslides 11:441-461.https://doi.org/10.1007/s10346-013-0404-6
Zhang LM,Xu Y,Huang RQ,et al.(2011)Particle flow and segregation in a giant landslide event triggered by the 2008Wenchuan earthquake,Sichuan,China.Natural Hazards and Earth System Science 11(4):1153-1162.https://doi.org/10.5194/nhess-11-1153-2011