Failure characteristics and mechanism of deposit slopes with bedrock for different soil moisture contents under seismic load

2022 ◽  
Vol 154 ◽  
pp. 107128
Author(s):  
Bing Yang ◽  
Zihong Zhou ◽  
Jiangrong Hou ◽  
Tao Yang ◽  
Junyun Zhang
2013 ◽  
Vol 807-809 ◽  
pp. 1648-1652
Author(s):  
Tie Jun Sun ◽  
Baderihu Tajilake

Experiment was executed to plant eco-grass of Bromus inermis Leyss on 15°bare slopes, and study effect of biological characters on dynamics of soil moisture contents. The results indicated that vegetation restored quickly on the bare slope after the eco-grass planted. There were 2473.4 kg/hm2 of overground biomass and 1744.1kg/hm2 of underground biomass, and 70% of underground biomass was in 0-10cm layer of soil. Meanwhile, there was a regulatory mechanism of soil moisture content for Bromus inermis Leyss. When rainfall was enough, soil moisture content in 0-80 cm layer could reach to the most of 26.83% quickly this year. Next it could decline near to the first value of 19.81% after rainfall stopped, and keep a dynamic balance between 19.48% and 19.96%. Moreover, the regulatory mechanism realized though underground biomass, and was clearer with underground biomass increasing, especially in the 0-40cm layer of soil.


2021 ◽  
Author(s):  
Vipin Kumar ◽  
Léna Cauchie ◽  
Anne-Sophie Mreyen ◽  
Philippe Cerfontaine ◽  
Mihai Micu ◽  
...  

<p>Seismic stability evaluation plays a crucial role in landslide disaster risk reduction. Related modeling also has to consider the potential influences of the rainfall on the hillslopes. This study aims at understanding the relative influence of the seismic loading and extreme cumulative rainfall on a massive active landslide in the seismically active Vrancea-Buzau region of the Romanian Carpathians (45° 30' 23" N, 26° 25' 05" E). This region has been subjected to more than 700 earthquakes (M>4) events with the highest magnitude of 7.2 (M<sub>w</sub>) during the year 1960-2019. Rainfall data of the year 2000-2019 revealed the occurrence of relatively intense rainfall events, especially during the last ten years. The landslide has an aerial dimension of ~9.1 million m². It hosts the small village of Varlaam at the toe along the Bisca River. The slope (with an average gradient of 15-20°) is covered by shrubs and scattered trees near its borders and is relatively barren in the central part. Shales with some intercalated sandstone layers belonging to the Miocene thrust belt constitute the rocks of the slope.   </p><p>A first survey involving the multi-station array and related Horizontal-to-Vertical noise Spectral Ratio (HVSR) measurements was completed in summer 2019. The findings of the HVSR were processed using the inversion process to infer the shear wave velocity distribution with depth and to detect the sliding surface of the landslide. These velocities were further used to estimate the geotechnical properties of the subsurface using the empirical equations. The HVSR based depth profiles and the Unmanned Air Vehicle based topographic information were used to take four 2D slope sections. These sections were considered for 2D discrete element modeling based stability evaluation under static and dynamic condition along with sensitivity analysis. Static simulation was used to determine the Factor of Safety (FS) using the shear strength reduction approach. Ricker wavelet was used as input seismic load in the dynamic simulation. Potential run-out and flow characteristics of the slope material were explored using the Voellmy rheology based RAMMS software. The relationship between rainfall, surface runoff, and soil moisture was also explored to understand the hydrogeological influence on slope stability.</p><p>Though the slope reveals meta-stability (1.0<FS<2.0) condition under static loading, displacement in the soil reaches up to 1.5 m that further increases to 2.8 m under dynamic loading. According to the topographic characteristics of the slope and to the presence of landslide material or intact bedrock near the surface, acceleration along the slope reaches a Peak Ground Acceleration in the range of 0.6 to 1.3g. Eight extreme rainfall events (>50mm/24 hours) during the year 2000-2019 are noted to temporally coincide with enhanced surface runoff and increased soil moisture in the region. Debris flow runout modeling indicated that the slope material may attain a maximum flow height and flow velocity of 13±0.8 m and 5±0.5 m/sec, respectively, along the river channel.</p><p><strong>Keywords: </strong>Landslide;<strong> </strong>Earthquake; Slope stability; Runout; SE Carpathian</p>


Ecotoxicology ◽  
2021 ◽  
Author(s):  
Thuanne Braúlio Hennig ◽  
Paulo Roger Lopes Alves ◽  
Tânia Toniolo ◽  
Felipe Ogliari Bandeira ◽  
William Eduardo dos Santos ◽  
...  

2018 ◽  
Vol XXIV (1) ◽  
pp. 27-40
Author(s):  
Juan Antonio Núñez-Colima ◽  
◽  
Aurelio Pedroza-Sandoval ◽  
Ricardo Trejo-Calzada ◽  
Ignacio Sánchez-Cohen ◽  
...  

2013 ◽  
Vol 35 (1) ◽  
pp. 61-68 ◽  
Author(s):  
Krystyna Elkner

Empty cavities were found already in very young cucumber fruits with diameter 1.5 cm. As the fruit develops the empty cavities augment and the number of fruits showing this defect increases. Low soil moisture and high nitrogen fertilization favour the formation of empty cavities. Their origination and changes were traced with anatomical methods in the course of fruit development. As a most plausible cause of their origination the author considers the enlargement of only part of the cells of the suture between the two (or three) carples. Due to this uneven enlargement of neighbouring cells strong mechanical tension probably arises amoung them, leading to the formation of ruptures separating these cells, consequently causing the separation of the carpel edges. Besides that, some of the cells of the suture which have markedly enlarged, often burst which also contributes to the formation of an empty cavity and enlarges its dimensions.


Author(s):  
Y. A. Unguwanrimi ◽  
A. M. Sada ◽  
G. N. Ugama ◽  
H. S. Garuba ◽  
A. Ugoani

Draft requirements of two animal – drawn (IAR) weeders operating on loam soil were determined in the study. The implements include a straddle row weeder and an emcot attached rotary weeder evaluated under the same soil conditions, using a pair of white Fulani breed of oxen. The animal draft requirement was first estimated from the animal ergonomics measurements. Using area of 0.054 hectare as experimental plot for each implement the draft requirement of each implement was investigated after taking soil samples for soil moisture content and bulk density determinations. The implements tested showed variation in their average draft requirement. The straddle row weeder had the highest value of 338.15 N respectively while the emcot attached rotary weeder had the lowest value of 188.12 N with 47.03%, respectively. The average soil moisture contents and bulk density were 13.0% and 1.46%/cm3, respectively.


2020 ◽  
Vol 145 (1) ◽  
pp. 12-17 ◽  
Author(s):  
Guoting Liang ◽  
Junhui Liu ◽  
Jingmin Zhang ◽  
Jing Guo

Drought has become an important factor limiting crop yields in China. As an important greenhouse horticultural crop in China, the research of tomato (Solanum lycopersicum L. cv. Jinpeng No.10) is of great theoretical and practical significance. In the study, four different relative soil moisture contents (74% to 80%, 55% to 61%, 47% to 52%, and 25% to 30%) were used to induce drought stress. We investigated changes in photosynthetic gas exchange, chlorophyll fluorescence, and other related physiological parameters in response to different relative soil moisture contents. Drought inhibited the photosynthesis of tomato significantly, as shown by a clear decline in the net photosynthetic rate. Our results indicated stomatal limitation and nonstomatal limitation were responsible for the photosynthesis reduction.


2011 ◽  
Vol 57 (No. 7) ◽  
pp. 321-325 ◽  
Author(s):  
A. Rehman ◽  
R. Ahmad ◽  
M. Safdar

Declining water is a great concern in production of rice, because rice is more sensitive to water deficiency which restricts normal rice growth resulting in enormous economic loss. A field experiment was conducted to study the effect of hydrogel in different sowing techniques of aerobic rice viz. flat, ridge, and bed sowing. Observations on soil moisture percentage before every irrigation, yield, and yield components of rice were recorded. Application of hydrogel improved soil moisture contents in all the three sowing techniques as compared to soil without hydrogel. More soil moisture contents met the crop water needs and increased the number of germinated seeds. As a consequence of more emergence and better stand establishment, the yield components were also improved increasing the yield of rice in hydrogel amended soil in all sowing techniques. However, sowing of rice on beds with hydrogel amendment was found the most effective; it not only improved the performance of aerobic rice but also enhanced growth and yield of aerobic rice more than other sowing techniques.


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