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Reproduction of the Sedimentary Disturbance Phenomenon of the Diexi Ancient Landslide-Dammed Lake under Earthquake

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Journal of Mountain Science 2015年第5期12卷 1181-1188页

作者： WEI Yu-feng WANG Xiao-qun SHENG Man ZHOU Zhou YUAN Yong state key laboratory of geohazard prevention & geoenvironment protection Chengdu University of Technology

Valuable geological and environmental information can be obtained from the 200 m thick lacustrine sediments in the Diexi lake(an ancient landslide-dammed lake) of the Minjiang River. The shaking table test method was employed to study the disturbance phenomena which occurred in the Diexi lake sediments. The results show that the disturbance phenomena were caused by liquefaction-induced flows in the unconsolidated lacustrine sediments, due to triggering by earthquakes. The deformations only occurred in unconsolidated sediment layers and not in consolidated layers. This means that a consolidated layer cannot be liquefied and disturbed again by an earthquake for a second time. The disturbance on one layer corresponds to only one earthquake. The temporal occurrence of earthquakes could be determined by disturbance layers generated at different ages. In total, 10 disturbed layers were found in the lacustrine sediments of the Diexi lake. The experiments showed that there were more than 10 earthquakes between 30 ka B.P. and 15 ka B.P. in the Diexi lake area based on the dating of the disturbed sediment layers.

关键词： Minjiang River Diexi lake Landslide Earthquake disturbance deformation Simulatingexperiment

Temperature effects on the mechanical properties of slates in triaxial compression test

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Journal of Mountain Science 2017年第12期14卷 2581-2588页

作者： MENG Lu-bo LI Tian-bin CAI Guo-jun state key laboratory of geohazard prevention and geoenvironment protection Chengdu University of Technology

High geothermal temperatures appear to be unfavorable for the construction of tunnels in slate rocks with high overburden. To investigate the mechanical characteristics of slates at various levels of geothermal temperature, conventional triaxial compression tests at different levels of confining stress were carried out at 4 different temperatures from 20℃ to 120℃. The obtained results show high confining pressures weaken the thermal effects on rock mechanical characteristics while higher temperatures enhance the effect of confining *** higher levels of confining stress the thermal effects on the rock strength characteristics decrease. The higher the temperature, the larger is the effect of confining pressure on the mechanical characteristics of the slate. Increase of temperature leads to a decrease of the peak strength but increases the deformability and ductility of the slate, the thermo effect on the peak strength and Poisson's ratio is larger than on the elastic modulus. Higher temperatures reduce the shear strength of slate, the decrease is mainly caused by a decrease of the cohesion. In general, the slate samples fail in shear failure.

关键词： Temperature effect Slate Mechanical feature Triaxial test

Rolling motion behavior of rockfall on gentle slope:an experimental approach

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Journal of Mountain Science 2017年第8期14卷 1550-1562页

作者： CUI Sheng-hua PEI Xiang-jun HUANG Run-qiu state key laboratory of geohazard prevention and geoenvironment protection Chengdu University of Technology

The effects of slope surface material, slope gradient, block shape, and block mass conditions on rockfall rolling velocity were estimated with orthogonal test approach. Visual analysis shows that the importance of the factors is slope surface material > slope gradient > block shape > block mass. All the factors except block mass have the F value greater than the critical value, suggesting that these three factors are the key factors affecting the rockfall rolling velocity. Factor interaction analysis shows that the effect of the slope gradient relies largely on the slope surface conditions, and the block shape has little influence if the slope gradient is larger than a critical value. An empirical model considering the three key factors is proposed to estimate the rolling velocity, of which the error is limited to 5% of the testing value. This model is validated by 73 field tests, and the prediction shows excellent correlation with the site test. Thus, this analysis can be used as a tool in the rockfall behavior analysis.

关键词： Rockfall Rolling motion Experiment approach Gentle slope Orthogonal test

Rapid Susceptibility Mapping of Co-seismic Landslides Triggered by the 2013 Lushan Earthquake Using the Regression Model Developed for the 2008 Wenchuan Earthquake

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Journal of Mountain Science 2013年第5期10卷 699-715页

作者： LI Wei-le HUANG Run-qiu XU Qiang TANG Chuan state key laboratory of geohazard prevention and geoenvironment protection Chengdu University of Technology

The primary objective of landslide susceptibility mapping is the prediction of potential landslides in landslide-prone areas. The predictive power of a landslide susceptibility mapping model could be tested in an adjacent area of similar geo- environmental conditions to find out the reliability. Both the 2oo8 Wenchuan Earthquake and the 2o13 Lushan Earthquake occurred in the Longmen Mountain seismic zone, with similar topographical and geological conditions. The two earthquakes are both featured by thrust fault and similar seismic mechanism This paper adopted the susceptibility mapping model of co-seismic landslides triggered by Wenchuan earthquake to predict the spatial distribution of landslides induced by Lushan earthquake. Six influencing parameters were taken into consideration： distance from the seismic fault, slope gradient, lithology, distance from drainage, elevation and Peak Ground Acceleration （PGA）. The preliminary results suggested that the zones with high susceptibility of co- seismic landslides were mainly distributed in the mountainous areas of Lushan, Baoxing and Tianquan counties. The co-seismic landslide susceptibility map was completed in two days after the quake and sent to the field investigators to provide guidance for rescue and relief work. The predictive power of the susceptibility map was validated by ROC curve analysis method using 2o37 co-seismic landslides in the epicenter area. The AUC value of o.71o indicated that the susceptibility model derived from Wenchuan Earthquake landslides showed good accuracy inpredicting the landslides triggered by Lushan earthquake.

关键词： Lushan earthquake Landslide Susceptibility mapping Logistical regression

Variation of cavity gas pressure in slopes with weak intercalation under seismic load

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Journal of Mountain Science 2016年第2期13卷 352-360页

作者： WANG Xiao-qun CHEN Zhen-lin ZHOU Zhou SHEN Man state key laboratory of geohazard prevention and geoenvironment protection Chengdu University of Technology

This study discussed how cavity gas pressure affects the stability of rock mass with fractures under well controlled laboratory ***-created void space created and the induced gas pressures have been the focus of active researches because they are associated with fast movement of large-scale landslides.A shaking table experiment was set up to mimic weak-intercalated rock slope under seismic *** cavity gas pressure would be produced in weak spots upon a sudden vibration *** drastically elevated gas pressure is believed to be responsible for the creation of cavities surrounding the tension *** dissipation of the excessive cavity gas pressure,the fractures are in unbounded *** observation explains that the slope body would be split and loosened under several aftershocks,and with the expanding of the cracks,the slope failure eventually *** research of the mechanism of cavity gas pressure could provide a novel insight into the formation mechanism of landslides under seismic load and has implications for the disaster prevention and control theory for the slope stability evaluation.

关键词： Landslide Fracture Deformation Weak intercalation Cavity gas pressure

Impact of polymer mixtures on the stabilization and erosion control of silty sand slope

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Journal of Mountain Science 2019年第2期16卷 470-485页

作者： YANG Qing-wen PEI Xiang-jun HUANG Run-qiu state key laboratory of geohazard prevention and geoenvironment protection Chengdu University of Technology

Silty sand can be prone to erosion because it is short of stability cementation materials. In recent years, various emerging soil stabilizers, especially natural organic substance and polymer, have been used to improve soil strength, water stability and ability of erosion resistance. In this study, a new type of soil stabilization additive modified carboxymethyl cellulose(M-CMC), consisting of carboxymethyl cellulose(CMC) and polyacrylamide(PAM), was developed for stabilization treatment of silty sand. A series of laboratory tests were conducted to evaluate the performance of M-CMC application on shear strength, permeability, water susceptibility and microstructure of the silty sand soil treated with additive concentration range of 0%-1.3%. Moreover, rainfall simulation experiments were conducted to evaluate the effect of M-CMC on the erosion control of silty sand which compacted soil in a large-sized runoff(1 m^2) plots. Test plot which treated with 1.1% concentration of soil stabilizer and control plot which treated with same amount of water were cured outdoor for 50 days before rainfall simulation test. Rainfall intensity was applied at 120 mm·h-1 for 60 min. Finally, a field test is performed in order to assess the practical application effect of silty sand with 1.1% M-CMC. In general, the results showed that an increase of the concentration of M-CMC resulted in an improvement in water susceptibility and shear strength but a decrease in the infiltration rate. Internal friction angle of the treated soil remarkably increased under a low M-CMC concentration(less than 0.7%), while cohesion of them sharply increased under a relatively high M-CMC concentration(larger than 0.7%). Water susceptibility of the treated samples was improved remarkably under a relatively high M-CMC concentration(larger than 0.7%). Permeability coefficient of them decreased significantly when the M-CMC concentration was increased from 0 to 0.5% and, then, from 0.9% to 1.3%. Based on the image

关键词： Soil stabilization Water susceptibility permeability Erosion Water retention Cementation

Debris Flow Susceptibility Assessment Using a Probabilistic Approach:A Case Study in the Longchi Area, Sichuan Province, China

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Journal of Mountain Science 2014年第4期11卷 1001-1014页

作者： CHANG Ming TANG Chuan ZHANG Dan-dan MA Guo-chao state key laboratory of geohazard prevention and geoenvironment protection Chengdu University of Technology

The Longchi area with the city of Dujiangyan, in the Sichuan province of China, is composed of Permian stone and diorites and Triassic sandstones and mudstones intercalated with slates. An abundance of loose co-seismic materials were present on the slopes after the May 12, 2008 Wenchuan earthquake, which in later years served as source material for rainfall-induced debris flows or shallow landslides. A total of 48 debris flows, all triggered by heavy rainfall on 13th August 20l0, are described in this paper. Field investigation, supported by remote sensing image interpretation, was conducted to interpret the co-seismic landslides in the debris flow gullies. Specific characteristics of the study area such as slope, aspect, elevation, channel gradient, lithology, and gully density were selected for the evaluation of debris flow susceptibility. A score was given to all the debris flow gullies based on the probability of debris flow occurrence for the selected factors. In order to get the contribution of the different factors, principal component analyses were applied. A comprehensive score was obtained for the 48 debris flow gullies which enabled us to make a susceptibility map for debris flows with three classes. Twenty-two gullies have a high susceptibility, twenty gullies show a moderate susceptibility and six gullies have a low susceptibility for debris flows.

关键词： Debris flow Landslide Probability Susceptibility assessment Grey correlation

Development of the nano-composite cement:Application in regulating grouting in complex ground conditions

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Journal of Mountain Science 2018年第7期15卷 1572-1584页

作者： WANG Sheng WANG Jing-fei YUAN Chao-peng CHEN Li-yi XU Shi-tong GUO Kai-bin state key laboratory of geohazard prevention & geoenvironment protection Chengdu University of Technology

Improvement of the fluidity and setting time of grouting materials has been recognized as an effective approach of seepage prevention in foundation works, and it is quite common to be used for handling severe leakages in complex ground conditions, such as loose, broken and fully fissured stratum. For the purposed of better meeting the engineering requirements, experimental studies were conducted in this study with focus on the nanocomposite grouting materials and the related controlled grouting technology. As compared with the commonly used silicate-sulpho-aluminate composite cement, which is characterized by relatively poor rheological property, quick setting time and low strength, the most suitable nano-material with proper reactants were selected intentionally to improve the mentioned attributes of composite cement. Due to the setting time and strength of the targeted cement slurry behaving with poor performance of harmonization to engineering construction problems, hydration synergistic effect of these composites were investigated in our experiments. Results showed that the properties of grouting materials, including initial fluidity, setting time, ideal right-angle thickening, and early strength and late strength were sufficient to produce an expected grouting application. It is therefore advocated that the refined grouting material could provide a better solution to fix grouting problems in complex ground cementing operations.

关键词： Nano-silica Silicate-sulpho-aluminate composite cement grout Controlled grouting Complex ground conditions

Progressive Modelling of the Gravity-induced Landslide Using the Local Dynamic Strength Reduction Method

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Journal of Mountain Science 2013年第4期10卷 532-540页

作者： CHEN Guo-qing HUANG Run-qiu XU Qiang LI Tian-bin ZHU Ming-lei state key laboratory of geohazard prevention and geoenvironment protection Chengdu University of Technology

The failure of slope is a progressive process, and the whole sliding surface is caused by the gradual softening of soil strength of the potential sliding surface. From this viewpoint, a local dynamic strength reduction method is proposed to capture the progressive failure of slope. This method can calculate the warning deformation of landslide in this study. Only strength parameters of the yielded zone of landslide will be reduced by using the method. Through continuous local reduction of the strength parameters of the yielded zone, the potential sliding surface developed gradually and evolved to breakthrough finally. The result shows that the proposed method can simulate the progressive failure of slope truly. The yielded zone and deformation of landslide obtained by the method are smaller than those of overall strength reduction method. The warning deformation of landslide can be obtained by using the local dynamic strength reduction method which is based on the softening characteristics of the sliding surface.

关键词： Landslide Local dynamic reduction Warning deformation Strength softening Progressive failure