Rainfall Infiltration

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Nurly Gofar - One of the best experts on this subject based on the ideXlab platform.

  • Saturated and unsaturated stability analysis of slope subjected to Rainfall Infiltration
    MATEC Web of Conferences, 2017
    Co-Authors: Nurly Gofar, Harianto Rahardjo
    Abstract:

    This paper presents results of saturated and unsaturated stability analysis of typical residual slopes subjected to Rainfall Infiltration corresponds to 50 years Rainfall return period. The slope angles considered were 45° and 70°. The saturated stability analyses were carried out for original and critical ground water level commonly considered by practicing engineer. The analyses were conducted using limit equilibrium method. Unsaturated stability analyses used combination of coupled stress–pore-water pressure analysis to evaluate the effect of Rainfall Infiltration on the deformation and transient pore-water pressure on slope stability. Slope stability analyses were performed at some times during and after Rainfall Infiltration. Results show that the critical condition for slope made by sandy material was at the end of Rainfall while for clayey material was at some specified times after the Rainfall ceased. Unsaturated stability analysis on sandy soil gives higher factor of safety because the soil never reached saturation. Transient analysis using unsaturated soil concept could predict more critical condition of delayed failure of slopes made up of clayey soil.

  • Effect Of Surface Boundary Condition On Rainfall Infiltration
    Jurnal Teknologi, 2012
    Co-Authors: Nurly Gofar, Min Lee Lee, Azman Kassim
    Abstract:

    Penyusupan air hujan amat dipengaruhi oleh keadaan sempadan permukaan tanah dan sifat–sifat hidraulik tanah. Kertas kerja ini mengetengahkan kajian mengenai kesan beberapa keadaan sempadan permukaan tanah terhadap penyusupan air hujan dengan menggunakan satu program komputer VADOSE/W. Satu kajian parametrik dijalankan untuk mengkaji kesan suhu persekitaran, kelembapan relatif udara, dan kelajuan angin terhadap penyejatan dan kadar penyusupan air hujan. Kesan konduktiviti hidraulik tanah terhadap mekanisma penyusupan air hujan juga dikaji dengan menggunakan dua model tiang tanah. Keputusan menunjukkan penyusupan air hujan adalah sensitif terhadap kelembapan relatif udara dan suhu persekitaran yang lebih rendah daripada suhu tanah, tetapi tidak sensitif terhadap kelajuan angin dan suhu persekitaran yang lebih tinggi daripada suhu tanah. Konduktiviti hidraulik tanah dan keamatan hujan mempunyai pengaruh yang besar terhadap mekanisme penyusupan dan pembentukan air larian permukaan. Maka, profil ketepuan tanah yang meyakinkan hanya boleh diperolehi jika keadaan sempadan permukaan tanah yang tepat dipertimbangkan dalam analisis. Kata kunci: Penyusupan air hujan, penyejatan, keadaan sempadan, konduktiviti hidraulik, model tiang tanah Rainfall Infiltration is greatly influenced by the surface boundary condition as well as hydraulic properties of soil. This paper highlights the study on the effect of several surface boundary conditions on the Rainfall Infiltration using a computer program VADOSE/W. A parametric study was carried out to study the effect of ambient temperature, relative humidity and wind speed on the evaporation and Rainfall Infiltration rate. The effect of soil hydraulic conductivity on the mechanism of Rainfall Infiltration was also studied by using two soil column models. Results show that Rainfall Infiltration is sensitive to relative humidity and ambient temperatures lower than soil temperature, but insensitive to wind speed and ambient temperatures higher than soil temperature. The hydraulic conductivity of soil and Rainfall intensity have great influence on the Infiltration mechanism and the development of surface runoff. Thus, reliable saturation profile can only be achieved if accurate surface boundary condition was considered for analysis. Key words: Rainfall Infiltration, evaporation, boundary condition, hydraulic conductivity, soil column model

  • Instrumented soil column model for Rainfall Infiltration study
    2008
    Co-Authors: Nurly Gofar, Min Lee Lee, Azman Kassim
    Abstract:

    Infiltration and changes on pore-water pressure in soil must be taken into account in most slope stability and seepage problems. Laboratory experiments were performed to examine one-dimensional Rainfall Infiltration behavior of unsaturated soil. This paper describe an apparatus designed in this study to investigate the mechanism of Rainfall Infiltration in soil, and to provide experimental evidence on the transient pore-water pressure distribution and redistribution of four different types of soils under various Rainfall conditions. The test results show that the model functioned properly to quantify the Rainfall intensity, surface runoff rate, pore-water pressure, and percolation flow rate. The response of suction distribution and redistribution to Rainfall Infiltration was influenced by the particle size of the soils.

  • Stability analysis of unsaturated slopes subjected to Rainfall Infiltration
    2008
    Co-Authors: Mohamed El-byhagi El-fadil, Nurly Gofar
    Abstract:

    Prolonged high intensity Rainfall which took place on 17 to 20 December has triggered a number of slope failures at Universiti Teknologi Malaysia (UTM) Skudai campus. Two instrumented slopes were investigated for the effects of soil characteristics on the mechanism of Rainfall Infiltration in slope. One slope (Site-1) failed due to the Rainfall on the 20th December 2006 while the other (Site- 2) remained stable. With other conditions deemed to be equal, the slope failure at Site-1 was predicted to be caused by the behavior of the soil forming the slope. Analysis showed that for Site 1, the continuous Rainfall has caused a significant increase in soil’s moisture, decrease in negative pore-water pressure (from 28 kPa to 0), and hence reduction in the factor of safety (FOS) of the slope from 2.15 to 0.99 for slip plane at depth of 1.8 m. On the other hand, the same Rainfall induces a very small change in negative pore-water pressure, and hence reduces the minimum FOS of slope at Site 2 from 3.34 to 2.78. The results showed that the permeability of the soil mass plays an important role in the slope instability; hence more attention should be given to the fine-grained soil slope during monsoon season. Comparison between predicted FOS based on SWCC curve and actual measurement showed that there are other factors that may influence the soil response to Rainfall Infiltration such as mineralogy of the clay content and the dispersibility of the soil.

Tony L. T. Zhan - One of the best experts on this subject based on the ideXlab platform.

  • Field study of Rainfall Infiltration into a grassed unsaturated expansive soil slope
    Canadian Geotechnical Journal, 2007
    Co-Authors: Tony L. T. Zhan, Del G. Fredlund
    Abstract:

    A full-scale field study was conducted to investigate the effects of Rainfall Infiltration on a natural grassed expansive soil slope in China. A 16 m wide × 28 m long area was selected for instrume...

  • Analytical Analysis of Rainfall Infiltration Mechanism in Unsaturated Soils
    International Journal of Geomechanics, 2004
    Co-Authors: Tony L. T. Zhan
    Abstract:

    To improve the understanding of the influence of hydraulic properties and Rainfall conditions on Rainfall Infiltration mechanism and hence on the pore-water pressure distributions in single and two-layer unsaturated soil systems, an analytical parametric study has been carried out. Parameters considered in this study include saturated permeability (ks), desaturation coefficient (α), water storage capacity (θs-θr), and antecedent and subsequent Rainfall Infiltration rate (qA and qB). Moreover, the influence of soil profile heterogeneity is also investigated. The calculated results demonstrate that the Infiltration process and pore-water pressure response are primarily controlled by both qα/ks and ks/α. Generally the larger the value of qα/ks , the greater the reduction of negative pore-water pressure in shallow soil layer. The larger the ratio of ks/α, the faster is the advancement of wetting front. Among the three hydraulic parameters, the effects of α and ks on pore-water pressure response are much more ...

Huang Zhi-fang - One of the best experts on this subject based on the ideXlab platform.

  • Analysis on the Impact of Expansive Soil Slope Stability by Rainfall Infiltration
    2018 International Conference on Engineering Simulation and Intelligent Control (ESAIC), 2018
    Co-Authors: Huang Zhi-fang
    Abstract:

    Expansive soil soften by water, leading to reduce soil strength, Rainfall Infiltration impact on the stability of expansive soil slope. In this paper, based on soil saturated - unsaturated seepage theory, by analysis on Rainfall Infiltration model used finite element analysis software, the model of expansive soil slope saturated - unsaturated Rainfall Infiltration was established to simulate groundwater rate and pressure head variation during Rainfall the influence of slope seepage field and stability by Rainfall Infiltration was analyzed. Conclusion is that expansive soil slope under Rainfall Infiltration affects only occurs in shallow areas, low permeability affects slope effect of rainwater Infiltration, fissured Infiltration slope is slightly faster, short-term Rainfall does not lead to a large area of the slope slumping damage, slope slip surface only in the surface layer, the performance of shallow slip. The theoretical basis and data reference are provided for expansion soil slope construction and protection.

Del G. Fredlund - One of the best experts on this subject based on the ideXlab platform.

Wang Zhao - One of the best experts on this subject based on the ideXlab platform.

  • Model tests on responses of unsaturated road-embankments to loading and Rainfall Infiltration
    Chinese Journal of Geotechnical Engineering, 2009
    Co-Authors: Wang Zhao
    Abstract:

    Under loading and Rainfall Infiltration,five series of model tests on unsaturated road-embankments with compaction degrees of 85%,90%,96% for Gansu loess and 93%,96% for Chongqing clay are respectively carried out,and the responses of the unsaturated road-embankments to loading and Rainfall Infiltration are obtained:1) With the increment of loading,the number of Rainfall and precipitation,the deformations and soil pressures of new constructed road-embankments gradually increase,but after loading,the increment of deformations and soil pressures caused by Rainfall is smaller than that caused by loading. For the embankment slope,the vertical displacements are smaller than those of embankment body,but the lateral displacements are greater than those of embankment body. Moreover,within the range of (1/3~1/2) height of the embankment slope from the foot of slope,and the lateral displacements of the embankment slope are the greatest,while within the range of about (1/3) height of the embankment slope from the foot of slope,the lateral soil pressures obviously increase with the increment of precipitation,so deformation failure of the embankment slope probably occurs first at this area. 2) For embankment slope filled with swelling soils,it is unsuitable that compaction degree is excessively high owing to the filled soils of the embankment slope bearing small superimposed loadings. 3) Water content and matrix suction nearby the foot of slope are subjected to the most influence of precipitation. The influence depth of Rainfall Infiltration relates to many factors,such as precipitation,Rainfall intensity,property of filled soil and compaction degree of road-embankment. Under the present model tests,the influence depths of Rainfall Infiltration for the road-embankments respectively filled with Gansu loess and Chongqing clay are all about 0.25 m,far smaller than the results of the field tests.