17 / 2021-10-20 09:06:11

Research on evolution law and critical deformation velocity of landslides in different deformation phases

engineering geology,early warning criterion,deformation velocity,evolution law,different deformation phases

Prediction and early warning is one of the hot and difficult issues in the field of international landslide study，and .there are some deficiencies in the research of the elapsed time and critical deformation velocity of landslides in different deformation phases currently. In order to further explore the evolution law and deformation velocity warning criterion of landslides，the landslide deformation evolution process is divided into four phases：initial deformation phase，uniform deformation phase，acceleration deformation phase，and sharp deformation phase. Based on landslide database information and using statistical analysis methods，the characteristics of elapsed time of landslides in different deformation phases and its correlation with different factors are studied， the development of cracks and macroscopic characteristics is summarized，and deformation velocity warning criterion of landslides in different phases is analyzed. The following results are drawn. (1) Accelerated deformation phase lasted anywhere from 18 days to 1 080 days，and the elapsed time of nearly half of the landslides locates in space 30 days to 90 days. Sharp deformation phase landslide majority lasts less than 30 days. (2) The elapsed time of landslides in different deformation phases correlates with failure mode，landslide volume and sliding surface type，wherein the relationship between elapsed time and sliding surface type is most closely. When the landslide slip surface is rigid structure，the acceleration and sharp deformation phase is short relatively，which is on the contrary when slip surface is weak bedding surface. (3) When landslide develops into acceleration deformation phase，the maximum width of crack is 1～50 cm，and when landslide develops into sharp deformation phase，the maximum width of crack is 4～126 cm，wherein the crack of soil landslide and talus slide is wider，and the crack of rock landslide is relatively narrow. (4) The critical deformation velocity of landslide is not more than 50 mm/d as developing into sharp deformation phase，when the threshold of toppling landslide is relatively large，and the threshold of landslide with weak sliding surface is larger than landslide with rigid sliding surface. (5) The critical deformation velocity of various landslides is not large as developing into acceleration deformation phase，which is closely related to the failure mode. The threshold of sliding landslide basically is no more than 4 mm/d，and the threshold of toppling landslide or collapse landslide is slightly larger，generally larger than 4 mm/d.