Study on Seepage Laws of Completely Weathered Phyllite Slope Under Rainfall

According to the available geological data and monitoring data, the completely weathered phyllite slope dilates and softens under the condition of continuous rainfall, which is then prone to instability failure. The indoor artificial rainfall test was carried out through the construction of the slope model, and the soil moisture sensor, pore water pressure sensor and matric suction sensor were used to study the variation laws of moisture content, pore water pressure and infiltration line at the back edge, slope body and the foot of the slope under continuous heavy rainfall. According to the sensor data and recorded information, with the influence of heavy rainfall over a long period of time, the water content and pore water pressure increased firstly, then decreased, and finally stabilized. The infiltration line moved from the top, the surface and the foot of the slope to the slope body, and shallow slip failure occurred in the shallow layer of the slope body.

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Laboratory Experiment and Numerical Analysis on the Precursory Hydraulic Process of Rainfall-Induced Slope Failure

Advances in Civil Engineering ◽

10.1155/2020/2717356 ◽

2020 ◽

Vol 2020 ◽

pp. 1-12

Author(s):

Joon-Young Park ◽

Young-Suk Song

Keyword(s):

Numerical Modeling ◽

Laboratory Test ◽

Water Content ◽

Pore Water ◽

Slope Failure ◽

Pore Water Pressure ◽

Water Pressure ◽

Volumetric Water Content ◽

Wetting Front ◽

Artificial Rainfall

A combined analysis involving a laboratory test and numerical modeling was performed to investigate the hydraulic processes leading to slope failure during rainfall. Through a laboratory landslide test in which artificial rainfall was applied to a homogeneous sandy slope, the timing and configurations of multiple slides were identified. In addition, volumetric water content was measured in real time through the use of monitoring sensors. The measured volumetric water content data were then used to validate the relevance of the numerical modeling results. The validated numerical modeling of the laboratory-scale slope failures provided insight into the hydraulic conditions that trigger landslides. According to the numerical modeling results, the miniaturized slope in the laboratory test was saturated in a manner so that the wetting front initially progresses downward and then the accumulated rainwater at the toe of the slope creates a water table that advances toward the crest. Furthermore, each of the five sequential failures that occurred during this experiment created slip surfaces where the pore-water pressure had achieved full saturation and an excessive pore-water pressure state. The findings of this study are expected to help understand the hydraulic prerequisites of landslide phenomena.

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A Numerical Investigation of the Deformation Mechanism of a Large Metro Station Foundation Pit under the Influence of Hydromechanical Processes

Geofluids ◽

10.1155/2021/5536137 ◽

2021 ◽

Vol 2021 ◽

pp. 1-16

Author(s):

Yan Wang ◽

Yongjun Zhang ◽

Mingfei Li ◽

Yi Qi ◽

Tianhui Ma

Keyword(s):

Pore Water ◽

Heavy Rainfall ◽

Pore Water Pressure ◽

Water Pressure ◽

Ground Surface ◽

Horizontal Displacement ◽

Horizontal Distance ◽

Foundation Pit ◽

Metro Station ◽

Ground Conditions

Considering the unique conditions of deep and large subway foundation pit excavation affected by heavy rainfall in soil-rock composite strata, this paper employs finite element numerical simulation methods to study foundation pit instability under the influence of heavy rainfall. According to the hydraulic coupling conditions caused by rainfall, a fluid-solid coupling numerical model for a deep and large subway foundation pit in soil-rock composite strata is established in this paper. By selecting the Anshan road station of Qingdao subway line 4 as the engineering background, various parameters related to foundation pit excavation affected by heavy rainfall at different excavation depths were analyzed. The study found that after the foundation pit was excavated, the surrounding pore water pressure decreased and the pore water pressure near the ground surface increased rapidly due to rainfall. As the horizontal distance from the foundation pit increased, the pore water pressure at the same depth also increased. The excavation of the foundation pit caused uplift of the bottom of the pit. After rainfall, the uplift value decreased compared with that before rainfall. With increasing excavation depth, the decreased value of the bottom uplift decreased and then increased. The rainfall caused the horizontal displacement of the pit walls on both sides of the pit to increase. When the excavation depth was 10 m, the horizontal displacements on both sides of the pit were equivalent. When the excavation depth was 20 m, the horizontal displacement was concentrated in the first 10 m; when the excavation depths were 30 m and 40 m, the horizontal displacement was concentrated in the first 13 m. This finding shows that when the foundation pit was affected by rainfall, the sidewall collapsed at a distance of 13 meters from the ground. As the excavation depth increased, the depth of excavation instability was closer to the bottom of the pit. The research in this paper can provide a reference for the construction of deep and large foundation pits in similar composite ground conditions that are affected by rainfall.

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A Study on Correlation between Pore Water Pressure, Rainfall and Landslide Occurrence

Journal of Civil Engineering Science and Technology ◽

10.33736/jcest.115.2013 ◽

2013 ◽

Vol 4 (2) ◽

pp. 24-27

Author(s):

Suhaimi D.N.A.A ◽

Selaman O. S.

Keyword(s):

Pore Water ◽

Heavy Rainfall ◽

Pore Water Pressure ◽

Water Pressure ◽

Microsoft Excel ◽

Exponential Relationship ◽

Saturation Condition ◽

Landslide Occurrence ◽

The Road ◽

Landslide Event

Landslides not only include loss of human lives and properties, but also effect the transportation direct and indirectly. This study focus on the correlation between rainfalls and pore water pressure which lead to landslide event. For this study, the scope of study focuses at Bau, Sarawak whereby lot of landslide event occurs along the road in 2009. Triaxial test is conduct in lab to measure pore water pressure which modeling landslide occurs on 11th January 2009 at KM 72.00 Bau-Lundu Road. From the laboratory test, it can be seen that continuous and heavy rainfall will increase the pore water pressure in soil. When the pore water pressure increase from 809.94 kPa to 829.25 kPa, the strength of the soil will be decrease due to the water content inside the soil. Other than that, correlation between pore water pressure and rainfall can be seen as an exponential relationship by plotting agraph using Microsoft Excel. It indicates that continuous rainfall within 11 days will increase the changes in pore water pressure and causes the soil to be in fully saturation condition. After 27 hours, the soil will be in failure which leads to landslide.

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Model testing on rainfall-induced landslide of loose soil in Wenchuan earthquake region

Natural Hazards and Earth System Science ◽

10.5194/nhess-12-527-2012 ◽

2012 ◽

Vol 12 (3) ◽

pp. 527-533 ◽

Cited By ~ 20

Author(s):

H. Fang ◽

P. Cui ◽

L. Z. Pei ◽

X. J. Zhou

Keyword(s):

Shear Strength ◽

Wenchuan Earthquake ◽

Pore Water ◽

Pore Water Pressure ◽

Water Pressure ◽

Experimental Investigations ◽

Soil Parameters ◽

Artificial Rainfall ◽

Loose Soil ◽

Porosity Ratio

Abstract. This study investigates the formation process of rainfall-induced landslide for slopes composed of loose soil in the Wenchuan earthquake region. Experimental investigations have been performed on the landslide's formation and the variation of the controlling soil parameters under various artificial rainfall conditions. The landslide triggering mechanisms can be described in the following way. Firstly, the large porosity of the loose soil facilitated the infiltration of water, which increased the pore water pressure and reduced the shear strength of the soil significantly. In addition, the rainfalls probably caused the concentration of finer particles at a certain depth of the valley slopes. This concentration within the soil increased the pore water pressure significantly, and consequently reduced both the porosity ratio and permeability. Therefore, when the pore water pressure reached a critical state, the effective shear strength of the soil diminished, inducing the landslide's formation.

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TIME TO THE END OF PRIMARY CONSOLIDATION (EOP) OF SOFT CLAYEY SOILS: CONCERNING THE EFFECT OF ATTERBERG’S LIMIT AND CYCLIC LOADING HISTORY

HUE UNIVERSITY JOURNAL OF SCIENCE TECHNIQUES AND TECHNOLOGY ◽

10.26459/hueuni-jtt.v128i2b.5424 ◽

2019 ◽

Vol 128 (2B) ◽

pp. 29-41

Author(s):

Trần Thanh Nhàn

Keyword(s):

Cyclic Loading ◽

Pore Water ◽

Pore Water Pressure ◽

Water Pressure ◽

Clayey Soils ◽

Loading History ◽

Cyclic Shear ◽

Wide Range ◽

Primary Consolidation ◽

Time Required

In order to observe the end of primary consolidation (EOP) of cohesive soils with and without subjecting to cyclic loading, reconstituted specimens of clayey soils at various Atterberg’s limits were used for oedometer test at different loading increments and undrained cyclic shear test followed by drainage with various cyclic shear directions and a wide range of shear strain amplitudes. The pore water pressure and settlement of the soils were measured with time and the time to EOP was then determined by different methods. It is shown from observed results that the time to EOP determined by 3-t method agrees well with the time required for full dissipation of the pore water pressure and being considerably larger than those determined by Log Time method. These observations were then further evaluated in connection with effects of the Atterberg’s limit and the cyclic loading history.

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Conjectures, Hypotheses, and Theories of Drumlin Formation (In memory of Stanislaw Baranowski)

Journal of Glaciology ◽

10.3189/s0022143000011552 ◽

1981 ◽

Vol 27 (97) ◽

pp. 503-505 ◽

Cited By ~ 1

Author(s):

Ian J. Smalley

Keyword(s):

Shear Strength ◽

Pore Water ◽

Stress Level ◽

Critical Stress ◽

Pore Water Pressure ◽

Water Pressure ◽

Glacial Till ◽

Forming Process ◽

Stress Levels

AbstractRecent investigations have shown that various factors may affect the shear strength of glacial till and that these factors may be involved in the drumlin-forming process. The presence of frozen till in the deforming zone, variation in pore-water pressure in the till, and the occurrence of random patches of dense stony-till texture have been considered. The occurrence of dense stony till may relate to the dilatancy hypothesis and can be considered a likely drumlin-forming factor within the region of critical stress levels. The up-glacier stress level now appears to be the more important, and to provide a sharper division between drumlin-forming and non-drumlin-forming conditions.

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