scholarly journals Study on formation mechanism of granite eluvium landslide by field rainfall simulation

2021 ◽  
Author(s):  
Wenkai Feng ◽  
Rui Hu ◽  
Huilin Bai ◽  
Yiying Wu ◽  
Hongchuan Dai
Keyword(s):  
Formation Mechanism ◽  
Physical Simulation ◽  
Water Pressure ◽  
Particle Migration ◽  
Local Failure ◽  
Rainfall Simulation ◽  
Residual Soil ◽  
Slope Surface ◽  
Soil Pressure ◽  
Slope Structure

Abstract Granite residual soil is a kind of special soil, which is easy to induce geological disasters under the condition of heavy rainfall. Taking the mass landslides in Beiling area, Longchuan County, Guangdong Province as the background, the formation mechanism of typical landslides was explored by means of physical simulation, and the following conclusions were obtained: ① the influencing factors of landslides were rainfall intensity, physical and mechanical properties of rock and soil mass, slope structure; ② Rainfall does not cause the abnormal increase or decrease of soil pressure and pore water pressure in the slope, indicating that the failure of the slope is limited to the local failure of the slope surface and the slope toe, and there is no overall deformation and failure trend; ③ On the surface of the slope, the slope is eroded by rainfall, and on the foot of the slope, the free surface collapses and undergoes erosion. On the whole, the slope shows the characteristics of "step by step retreat and damage in turn"; ④ The evolutionary process of landslide can be divided into the following four stages: original slope evolution stage, soil particle migration stage, slope surface local failure stage and overall instability stage.

The Test Study to the Changes of Excess Pore Water Pressure during Precast Pile Construction

2012 ◽  
Vol 193-194 ◽  
pp. 1010-1013
Author(s):  
Shu Qing Zhao
Keyword(s):  
Pore Water ◽  
Clayey Soil ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Excess Pore Pressure ◽  
Soil Pressure ◽  
Excess Pore Water Pressure ◽  
Test Study ◽  
Excess Pore

The construct to precast pile in thick clayey soil can cause the accumulation of excess pore water pressure. The high excess pore pressure can make soil, buildings and pipes surrounded have large deflection, even make them injured. Combining with actual projects, this paper presents an in-situ model test on the changes of excess pore water pressure caused by precast pile construct. It is found that the radius of influence range for single pile driven is about 15m，the excess pore water pressure can reach or even exceed the above effective soil pressure, and there are two relatively stable stages.

scholarly journals Numerical Simulation on the Whole Sinking Process of Open Caisson with an Improved SPH Method

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Jiahe Zhang
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Dynamic Change ◽  
Soil Pressure ◽  
Shield Tunneling ◽  
Material Interfaces ◽  
Engineering Problems ◽  
Domain Truncation ◽  
Particle Hydrodynamics ◽  
Sph Simulation

The phenomena of dynamic change in the material interfaces and mechanical properties are often involved in the caisson construction. Using conventional methods to simulate these phenomena is quite difficult due to the extremely large deformation. In this study, we proposed an improved soil-water-caisson interaction algorithm with the method of smoothed-particle hydrodynamics (SPH). This algorithm dealt with the support domain truncation of the particles near the blade and applied δ − SPH to avoid the pressure fluctuation. Meanwhile, the application of dynamic particles birth and death method could simulate the whole sinking process of an open caisson with underwater soil excavation. According to the comparison between SPH simulation and centrifuge test, the distribution of sidewall effective soil pressure was consistent, which indicated promising applicability of the algorithm. It should be noted that the considerable excess pore water pressure appeared in the surrounding soil under the blade. With the dissipation of the pressure over time, the effective soil stress increased correspondingly, and it would lead to the increasing difficulty of the sinking process. Therefore, the caisson should be avoided to stop for a long time during the sinking process or it would cause the stagnation of sinking. This algorithm could simulate engineering problems involving underwater construction effectively and provide theoretical and technical support for underwater excavation, shield tunneling, and other engineering problems.

Infiltration characteristics of two instrumented residual soil slopes

2003 ◽  
Vol 40 (5) ◽  
pp. 1012-1032 ◽  
Author(s):  
Illias Tsaparas ◽  
Harianto Rahardjo ◽  
David G Toll ◽  
Eng-Choon Leong
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Field Measurements ◽  
Residual Soil ◽  
Rainfall Runoff ◽  
Rainfall Events ◽  
Pore Water Pressures ◽  
Soil Slopes ◽  
Pressure Changes

This paper presents the analysis of a 12 month long field study of the infiltration characteristics of two residual soil slopes in Singapore. The field measurements consist of rainfall data, runoff data of natural and simulated rainfall events, and pore-water pressure changes during infiltration at several depths and at several locations on the two slopes. The analysis of the field measurements identifies the total rainfall and the initial pore-water pressures within the two slopes as the controlling parameters for the changes in the pore-water pressures within the slopes during infiltration.Key words: infiltration, rainfall, runoff, pore-water pressure, field measurements.

A new numerical method to approximate root water uptake fluxes in a mixed-dimensional 1D-3D setting

2021 ◽  
Author(s):  
Timo Koch ◽  
Hanchuan Wu ◽  
Kent-André Mardal ◽  
Rainer Helmig ◽  
Martin Schneider
Keyword(s):  
Analytical Solutions ◽  
Water Pressure ◽  
Numerical Test ◽  
Three Dimensional ◽  
Root Water Uptake ◽  
Richards Equation ◽  
Soil Pressure ◽  
Approximation Accuracy ◽  
Flux Approximation ◽  
Local Water

<p>1D-3D methods are used to describe root water and nutrient uptake in complex root networks. Root systems are described as networks of line segments embedded in a three-dimensional soil domain. Particularly for dry soils, local water pressure and nutrient concentration gradients can be become very large in the vicinity of roots. Commonly used discretization lengths (for example 1cm) in root-soil interaction models do not allow to capture these gradients accurately. We present a new numerical scheme for approximating root-soil interface fluxes. The scheme is formulated in the continuous PDE setting so that is it formally independent of the spatial discretization scheme (e.g. FVM, FD, FEM). The interface flux approximation is based on a reconstruction of interface quantities using local analytical solutions of the steady-rate Richards equation. The local mass exchange is numerically distributed in the vicinity of the root. The distribution results in a regularization of the soil pressure solution which is easier to approximate numerically. This technique allows for coarser grid resolutions while maintaining approximation accuracy. The new scheme is verified numerically against analytical solutions for simplified cases. We also explore limitations and possible errors in the flux approximation with numerical test cases. Finally, we present the results of a recently published benchmark case using this new method.</p>

scholarly journals Laboratory study on response of underwater cohesive sediment to columnar vibration source

2018 ◽  
Vol 54 (3) ◽  
pp. 193-202
Author(s):  
Peng Zhao ◽  
Feier Chen ◽  
Guoliang Yu
Keyword(s):  
Pressure Distribution ◽  
Experimental Observation ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Near Field ◽  
Mechanical Vibration ◽  
Cohesive Sediment ◽  
Vibration Source ◽  
Soil Pressure

Abstract This paper investigates the responses of cohesive sediment to mechanical vibration by experimental observation, containing: (1) the dynamic soil pressure, dynamic pore water pressure and dynamic acceleration to the vibration source; (2) the soil pressure distribution in the near field centered in an artificial columnar vibration source. Under the mechanical vibration with a frequency of 200 Hz and an amplitude of 1.15 mm, the dynamic soil pressure, dynamic pore water pressure and dynamic acceleration of underwater viscous sediment were measured in the sediment of four different depositing conditions. Results of the dynamic soil pressure, dynamic pore water pressure and dynamic acceleration of underwater viscous sediment in the near field responding to artificial vibration source are exhibited and discussed. It is found that, excited by the sinusoidal vibrator, the soil pressure presents a response of statistical sinusoidal fluctuation with the same frequency to the vibration source. In the sediment of lower initial yield stresses, the soil pressure distribution distinctly tends to firstly increase and then decrease with distance. The amplitude of the soil pressure is attenuated exponentially with distance.

Study on Slope Instability Disciplinarian on the Condition of Rainfall

2013 ◽  
Vol 353-356 ◽  
pp. 654-658
Author(s):  
Nan Tong Zhang ◽  
Xiao Chun Zhang ◽  
Hua Rong Wang ◽  
Chen Yan
Keyword(s):  
Slope Stability ◽  
Tensile Stress ◽  
Rainfall Intensity ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Road Construction ◽  
Slope Instability ◽  
Slope Surface ◽  
Large Area ◽  
Break Zone

Slope stability is one of the problems of road construction which should be faced with and solve. Rainfall can reduce the shear strength of slope soil and raise the underground water level which can lead to increase slope soil pore water pressure. The influence of rainfall infiltration on slop is mainly to change the slope seepage field, increase dynamic and hydrostatic water load on the slope soil and decrease of soil shear parameters. More abundant rainfall of typhoon area could make the road slope stability more fragile. Based on Matoushan Mountain along 104 state roads in Taizhou city, Zhejiang province, slope instability disciplinarian on the condition of rainfall is studied using the method of numerical simulation in this paper. As the results, when the rainfall intensity was 0.006 m/h and continuous rain was in 24 hours, the slope surface compressive stress tends to zero which began to appear tensile stress area on the condition of self-weight. And when the rainfall intensity was 0.01 m/h and continuous rain was in 24 hours, the large area of the slope surface was tensile stress area which means to appear break zone in slope surface and likely to landslide at the same time.

In Situ Study on Soil Disturbance Induced by Shield Tunneling in Tianjin

2013 ◽  
Vol 368-370 ◽  
pp. 1674-1677
Author(s):  
Yong Hua Cao ◽  
Xiao Qiang Kou
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soil Disturbance ◽  
Ground Settlement ◽  
Soil Pressure ◽  
Shield Tunneling ◽  
Tunnel Face ◽  
Tunneling Process

In urban environment, the soil disturbance induced by shield tunneling can be sensitive because it can cause deformation of the ground and damage the near structure. To study this disturbance in the construction process of Tianjin metro line No.3, in-situ monitoring of pore water pressure, soil pressure and ground settlement were conducted. The pore water pressure was monitored for the soil around the tunnel. The soil pressure was monitored for the soil around the tunnel and on the tunnel face. It was revealed that the pore water pressure and soil pressure changed twice in the tunneling process and these changes were induced by cutting face and grouting at the shield tail. The soil pressure on the tunnel face reached its maximal value when the distance between the cutting face and the sensor elements was around the diameter of the tunnel. Ground settlement developed in the tunneling process. The shape of ultimate settlement trough is closed to the one obtained by Pecks method.

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