Mechanism of Earthquake-triggered Loess-mudstone Interface Landslide in Tianshui Area, Gansu Province

doi:10.19657/j.geoscience.1000-8527.2019.01.21

Abstract

Abstract:

Taking the large loess-mudstone interface landslide in Tianshui area, Gansu Province as a case study, the characteristics of earthquake-triggered landslide development and stability were analyzed and evaluated based on field geological survey, engineering geological drilling, lab-based mechanical tests and FLAC^3D numerical calculation. The results show that most of these landslides are historical earthquake-triggered landslides, and their failure types are mainly slip-pull. Through calculating and analyzing the stability of these landslides, it is suggested that the slopes are currently stable. Under the influence of earthquakes, the slope stability would be markedly reduced, and the slope may have a secondary slip. The predicted slip surface is located at the loess-mudstone interface, consistent with the field survey results. Our finding is important in early-stage landslide recognition and provides scientific basis for landslide-related disaster prevention in Tianshui area.

Key words: loess-mudstone landslide, development characteristic, stability, landslide mechanism

CLC Number:

SUN Ping, ZHU Enzhen, ZHANG Shuai, HAN Shuai, WANG Gang. Mechanism of Earthquake-triggered Loess-mudstone Interface Landslide in Tianshui Area, Gansu Province[J]. Geoscience, 2019, 33(01): 218-226.

Figures/Tables 12

Fig.1 Cross section and local features of typical landslides

Fig.2 Calculation model of slope stability analysis

Table 1 Geomechanical parameters of rocks and soils

岩土体材料	抗剪强度		密度/ (kg/m³)	泊松比	变形模量 /MPa
岩土体材料	黏聚力 /kPa	内摩擦角/(°)	密度/ (kg/m³)	泊松比	变形模量 /MPa
Q₄黄土	49.6	18.58	1 640	0.30	18.5
Q₃黄土	48.6	19.41	1 570	0.27	17.0
强风化泥岩	15.0	12.00	2 000	0.24	54.0
弱风化泥岩	100.0	40.00	2 100	0.11	772.3
基岩	1 000.0	60.00	2 400	0.45	1 000.0

Fig.3 Corrected Fourier spectrum, energy spectrum and input acceleration time curve

Fig.4 Distribution of the model plastic zone

Fig.5 Static calculation results of the model

Fig.6 Distribution of plasticity region of the dynamic calculation model

Fig.7 Dynamic calculation results of the model

Fig.8 Comparison of sliding surface under the statics and dynamics of the landslide

Fig.9 Schematic diagram of the sliding area under dynamic action

Fig.10 Distribution map of monitoring points on the slope in dynamic calculation

Fig.11 Acceleration and speed curves of the monitoring point in the landslide

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