scholarly journals The Evolution of Pore Water Pressure in a Saturated Soil Layer between Two Draining Zones by Analytical and Numerical Methods

2015 ◽  
Vol 05 (04) ◽  
pp. 390-398
Author(s):  
Abib Tall ◽  
Cheikh Mbow ◽  
Daouda Sangaré ◽  
Mapathé Ndiaye ◽  
Papa Sanou Faye
Keyword(s):  
Numerical Methods ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soil Layer ◽  
Saturated Soil

Study on Reinforce Saturated Soft Clay Foundation with Dynamic Consolidation by Drainage

2013 ◽  
Vol 438-439 ◽  
pp. 1171-1175
Author(s):  
Zhi Li Sui ◽  
Zhao Guang Li ◽  
Xu Peng Wang ◽  
Wen Li Li ◽  
Tie Jun Xu
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Clay ◽  
Soil Layer ◽  
Good Effect ◽  
Loading Test ◽  
Test Plate ◽  
Dynamic Consolidation ◽  
Saturated Soft Clay

Dynamic consolidation method has been widely used in improving soft land, but always inefficient to saturated soft clay land, which is hard to improve, and even leads to rubber soil. Dynamic and drain consolidation method will deal with it well, with drainage system, pore-water can be expelled instantly from saturated soft clay as impacting. The pore-water pressure and earth pressure test in construction, the standard penetration test, plate loading test, geotechnical test after construction, which are all effective methods for effect testing. There is a comprehensive detection through different depth of soil layer with different detecting means on construction site. The results show that improving saturated soft clay land with dynamic and drain consolidation method has obtained good effect, and the fruit can be guidance for such construction in the future.

scholarly journals Influence of pore water pressure change on consolidation behavior of saturated poroelastic medium

2020 ◽  
Vol 382 ◽  
pp. 375-379
Author(s):  
Chao-Lung Yeh ◽  
Wei-Cheng Lo ◽  
Cheng-Wei Lin ◽  
Chung-Feng Ding
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Saturated Porous Medium ◽  
Water Pressure ◽  
Soil Layer ◽  
Pressure Change ◽  
Clay Layer ◽  
Poroelastic Medium ◽  
Total Settlement ◽  
Consolidation Behavior

Abstract. There are many factors causing land subsidence, and groundwater extraction is one of the most important causes of subsidence. A set of coupled partial differential equations are derived in this study by using the poro-elasticity theory and linear stress-strain constitutive relation to describe the one-dimensional consolidation in a saturated porous medium subjected to pore water pressure change due to groundwater table depression. Simultaneously, the closed-form analytical solutions for excess pore water pressure and total settlement are obtained. To illustrate the consolidation behavior of the poroelastic medium, the saturated layer of clay sandwiched between two sand layers is simulated, and the dimensionless pore water pressure changes with depths and the dimensionless total settlement as function of time in the clay layer are examined. The results show that the greater the water level change in the upper and lower sand layers, the greater the pore water pressure change and the total settlement of the clay layer, and the more time it takes to reach the steady state. If the amount of groundwater replenishment is increased, the soil layer will rebound.

scholarly journals Bench-Scale Experiments on Effects of Pipe Flow and Entrapped Air in Soil Layer on Hillslope Landslides

Geosciences ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 138 ◽  
Author(s):  
Yasutaka Tanaka ◽  
Taro Uchida ◽  
Hitoshi Nagai ◽  
Hikaru Todate
Keyword(s):  
Water Supply ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soil Layer ◽  
Silica Sand ◽  
Bench Scale ◽  
Drainage Capacity ◽  
Entrapped Air ◽  
Model Slope

Soil pipes are commonly found in landslide scarps, and it has been suggested that build-up of pore water pressure due to clogged soil pipes influences landslide initiation. Several researchers have also suggested that entrapped air in the soil layer increases the pore water pressure. We carried out bench-scale model experiments to investigate the influence of soil pipes and entrapped air on the build-up of pore water pressure. We installed a water supply system consisting of an artificial rainfall simulator, and used a water supply tank to supply water to the model slope and artificial pipe. We used two types of artificial pipe: A straight pipe, and a confluence of three pipes. Furthermore, we placed a layer of silica sand on top of the model slope to investigate the effect of entrapped air in the soil layer on the build-up of pore water pressure. Silica sand is finer than the sand that we used for the bulk of the model slope. Our results indicate that, although artificial pipes decrease the pore water pressure when the amount of water supplied was smaller than the pipe drainage capacity, the pore water pressure increased when the water supply was too large for the artificial pipe to drain. In particular, the confluence of pipes increased the pore water pressure because the water supply exceeded the drainage capacity. The results also indicate that entrapped air increases the pore water pressure in the area with relatively low drainage capacity, too. Based on these results, we found that although soil pipes can drain a certain amount of water from a soil layer, they can also increase the pore water pressure, and destabilize slopes. Furthermore, entrapped air enhances the trend that the pore water pressure can increase in the area with relatively low drainage capacity, as pore water pressure increases when too much water is supplied, and the artificial pipe cannot drain all of it.

scholarly journals Numerical Evaluation of The Nonlinear Behavior of Soil-Pile Interaction Under The Effect of Coupled Static-Dynamic Loads

2021 ◽  
Author(s):  
Duaa Al-Jeznawi ◽  
ISMACAHYADI Mohamed Jais ◽  
Bushra S. Albusoda
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Three Dimensional ◽  
Ground Surface ◽  
Frictional Resistance ◽  
Saturated Soil ◽  
Shaking Table ◽  
Physical Models ◽  
Soil Layers

Abstract Liquefaction of saturated soil layers is one of the most common causes of structural failure during earthquakes. Liquefaction occurs as a result of increasing pore water pressure, whereby the rise in water pressure occurs due to unexpected change in stress state under short-term loading, i.e., shaking during an earthquake. Thus, general failure occurs when the soil softens and eliminates its stiffness against the uplift pressure from the stability of the subsurface structure. In this case, the condition of soil strata is considered undrained because there is not enough time for the excess pore water pressure to dissipate when a sudden load is applied. To represent the non-linear characteristics of saturated sand under seismic motions in Kobe and Ali Algharbi earthquakes, the computational model was simulated using the UBCSAND model. The current study was carried out by adopting three-dimensional-based finite element models that were evaluated by shaking table tests of a single pile model erected in the saturated soil layers. The experimental data were utilized to estimate the liquefaction and seismicity of soil deposits. According to the results obtained from the physical models and simulations, this proposed model accurately simulates the liquefaction phenomenon and soil-pile response. However, there are some differences between the experiment and the computational analyses. Nonetheless, the results showed good agreement with the general trend in terms of deformation, acceleration, and liquefaction ratio. Moreover, the displacement of liquefied soil around the pile was captured by the directions of vectors generated by numerical analysis, which resembled a worldwide circular flow pattern. The results revealed that during the dynamic excitation, increased pore water pressure and subsequent liquefaction caused a significant reduction in pile frictional resistance. Despite this, positive frictional resistance was noticed through the loose sand layer (near the ground surface) until the soil softened completely. It is worth mentioning that the pile exhibited excessive settlement which may attribute to the considerable reduction, in the end, bearing forces which in turn mobilizing extra end resistance.

scholarly journals Three-Dimensional Upper Bound Limit Analysis on the Collapse of Shallow Soil Tunnels considering Roof Stratification and Pore Water Pressure

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Hong-Tao Wang ◽  
Ping Liu ◽  
Chi Liu ◽  
Xin Zhang ◽  
Yong Yang ◽  
...  
Keyword(s):  
Pore Water ◽  
Upper Bound ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Nonlinear Coefficient ◽  
Soil Layer ◽  
Three Dimensional ◽  
Support Pressure ◽  
Flow Rule ◽  
Soil Cohesion

Based on the plastic upper bound theorem, a three-dimensional kinematically admissible velocity field is constructed for the collapse of the soil masses above a shallow tunnel. In this field, this paper considers the influences of the roof stratification, pore water pressure, ground overload, and support pressure. This study deduced the upper bound solutions of the weight of the collapsed soil masses and the corresponding collapse surfaces by utilizing the nonlinear failure criterion, associated flow rule, and variation principle. Furthermore, we verified the validity of the proposed method in this paper by comparing this research with the existing work and numerical simulation results. This study obtains the influence laws of varying parameters on the area and weight of the collapsed soil masses. The results reveal that the area and weight of the collapsed soil masses increase with increasing support pressure and soil cohesion, but decrease with increasing thickness of the upper soil layer, nonlinear coefficient, pore water pressure, and ground overload. Among them, the roof stratification, pore water pressure, soil cohesion, and nonlinear coefficient have a significant influence on tunnel collapse, which should be given special consideration in engineering design.

Characteristics of nonlinear response of deep saturated soil deposits

1997 ◽  
Vol 87 (2) ◽  
pp. 342-355 ◽  
Author(s):  
Shean-Der Ni ◽  
Raj V. Siddharthan ◽  
John G. Anderson
Keyword(s):  
Resonant Frequency ◽  
Soil Properties ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Saturated Soil ◽  
Soil Conditions ◽  
Base Excitation ◽  
Soil Deposits ◽  
Stress Dependent

Abstract Recent EPRI seismic design guidelines call for dynamic soil properties (shear modulus ratio and damping) and liquefaction strength curves to be characterized as a function of the effective vertical stress (or depth). A modified version of the DESRA2 constitutive model for saturated soil has been applied to study the nonlinear seismic response including liquefaction of medium dense soil deposits of various thicknesses. The results of the stress-dependent soil properties model show lower deamplification and higher first-mode (resonant) frequency than that of the stress-independent soil properties model. By using the stress-dependent model with impulse base excitation, the nonlinear behavior of various soil deposits has been investigated under a variety of conditions. The results show that (1) the saturated soil deposit has a smaller surface amplitude and significantly lower resonant frequency than the unsaturated soil deposit of the same thickness; (2) for the saturated soil conditions, the larger the base excitation, the lower the surface amplification and the resonant frequency; (3) the deep soil deposits show lower surface amplification and resonant frequency compared to the response of shallow deposits; (4) when shallow and deep deposits are compared, the shallow deposits develop much higher residual pore-water pressure; and (5) the amplification and residual pore-water-pressure response of deposits deeper than 100 m or so are very similar. The application of the method has also been illustrated using a strong synthetic base excitation applied to the base at a site near Reno. The results in general are consistent with those computed using the impulse loading. The study reveals that the response predicted from the conventionally used stress-independent soil properties model is unconservative for deep deposit.

Analysis of One-Dimensional Thermal Consolidation of Saturated Soil with and without Thermo-Mechanical Coupling

2012 ◽  
Vol 594-597 ◽  
pp. 335-338
Author(s):  
Xue Shen ◽  
Rui Qian Wu
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Saturated Porous Medium ◽  
Water Pressure ◽  
Saturated Soil ◽  
Excess Pore Water Pressure ◽  
One Dimensional ◽  
Mechanical Coupling ◽  
Thermal Consolidation ◽  
Excess Pore

Based on a one-dimensional thermal consolidation formulation with and without thermo-mechanical coupling of saturated porous medium, problems of one-dimensional thermal consolidation of saturated soil were investigated. For the condition with instantaneous constant surface temperature and uniform initial pore-pressure, analytical solutions of excess pore-water pressure and temperature increment were derived respectively by the method of finite Fourier transform and inverse transform. A relevant computer program was developed, and the excess pore-water pressure was compared in detail. The results show that the thermo-mechanical coupling item in the thermal consolidation equation can be ignored.

scholarly journals Analytical solution for one-dimensional consolidation of double-layered soil with exponentially time-growing drainage boundary

2018 ◽  
Vol 14 (10) ◽  
pp. 155014771880671 ◽  
Author(s):  
Wenbing Wu ◽  
Mengfan Zong ◽  
M Hesham El Naggar ◽  
Guoxiong Mei ◽  
Rongzhu Liang
Keyword(s):  
Analytical Solution ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soil Layer ◽  
Excess Pore Water Pressure ◽  
One Dimensional ◽  
Present Solution ◽  
The One ◽  
Excess Pore

In this article, the exponentially time-growing drainage boundary is introduced to study the one-dimensional consolidation problem of double-layered soil. First, the one-dimensional consolidation equations of soil underlying a time-dependent loading are established. Then, the analytical solution of excess pore water pressure and average consolidation degree is obtained by utilizing the method of separation of variables when the soil layer is separately undergone instantaneous load and single-stage load. The validity of the present solution is proven by the comparison with other existing analytical solution. Finally, the influence of soil properties and loading scheme on the consolidation behavior of soil is investigated in detail. The results indicate that, the present solution can be degraded to Xie’s solution utilizing Terzaghi’s drainage boundary by adjusting the interface parameter, that is to say, Xie’s solution can be regarded as a special case of the present solution. The interface parameter has a significant influence on the excess pore water pressure of soil, and the larger interface parameter means the better drainage capacity of the soil layer.

scholarly journals Modelling of flowslides and debris avalanches in natural and engineered slopes: a review

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Sabatino Cuomo
Keyword(s):  
Numerical Methods ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Numerical Models ◽  
Water Pressure ◽  
Lateral Spreading ◽  
Slope Instability ◽  
Key Factors ◽  
Flow Type ◽  
Debris Avalanches

Abstract Background The landslides of the flow-type are dangerous and also challenging to study. A wide literature has been investigating the principal mechanisms governing each stage in which these phenomena can be ideally subdivided: failure, post-failure and propagation. However, holistic contributions and general overviews are very rare. In addition, a number of numerical methods have been issued and validated so that new chances exist to efficiently model those threats. The paper focuses on two classes of rainfall-induced landslides of the flow-type, namely debris flows and debris avalanches. The principal numerical methods are reviewed for modelling the landslide initiation and propagation and are later used for analyzing a series of benchmark slopes and real case histories which are successfully simulated. Results The rainfall from ground surface and water spring from the bedrock are key factors for slope instability. Pore water pressure plays a relevant role also during the propagation stage. The entrainment of further material makes the propagation patterns complex due to lateral spreading and slow-down of the front of flows. It is shown that the used models are capable to provide useful indications even for combined channelized and unchannelized flows. Conclusions Notwithstanding the complexity of flow-like landslides and the related challenges in modelling, the understanding and forecasting of such natural hazards is achievable with a satisfactory confidence. Among the key factors, rainfall, pore water pressure and bed entrainment deserves a special attention. Further improvements are expectable as the numerical models are becoming more efficient. Thus, more accurate descriptions of local effects will be possible and also additional mechanisms will be eventually analysed.

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