Numerical Modelling of an Unsaturated Capillary Barrier Cover System Using HYDRUS-2D for Percolation Control |Chapter 7 | Current Concepts in Engineering Research and Technology Vol. 1

 

Inclined multi-layered barriers can be used to protect underlying waste storage facilities. The intended barriers can confine infiltration through the implementation of the capillary barrier effect. In this study, the effect of rainfall, evaporation, and transpiration on the hydraulic properties of inclined covers was assessed by performing simulations using HYDRUS-2D numerical models. The material layers included clay loam soil as a seepage control layer, sandy soil as a moisture retention layer, and gravel as a capillary break layer. The numerical analysis simulated 20 years of climatological data (2000-2019) from Windsor, Canada, representing humid conditions with variable precipitation and evapotranspiration patterns.

 

Key quantitative results indicate that 21.09% of cumulative net rainfall was converted to lateral drainage along the sloped interfaces, while 78.91% of infiltrated water eventually exited through the bottom boundary as vertical percolation. The mean flux across the bottom boundary was 206.70 cm/day (2.39×10⁻⁶ m/s), demonstrating minimal deep percolation under the prevailing climatic conditions. Lateral diversion occurred at the interface between the seepage control layer and moisture retention layer due to the significant slope (10%) and contrasting hydraulic properties of adjacent layers. At reduced degrees of saturation, water movement between layers was restricted by low hydraulic conductivity, with the negative pressure head in the seepage control layer having minimal effect on water content in underlying layers.

 

This modelling approach, which uniquely combines an inclined multi-layer configuration with long-term transient climatic forcing, demonstrates that properly designed capillary barrier covers can effectively minimise leachate generation in waste containment systems. The findings provide quantitative design guidance for landfill covers in humid regions, showing that 10% slopes with layered clay loam, sand, and gravel materials achieve the capillary barrier effect under variable climatological conditions. The performance of this protective earthen cover can be guaranteed under the current climatological conditions, offering engineers a validated numerical framework for optimising waste containment cover designs.

 

Author(s) Details

Mohammad Ali Hagh Shenas
Department of Civil Engineering, Razi University, Kermanshah, Iran.

 

Hassan Sharafi
Department of Civil Engineering, Razi University, Kermanshah, Iran.

 

Please see the book here :- https://doi.org/10.9734/bpi/ccert/v1/7166

Suction-Enabled Retrograde Intrarenal Surgery: Technical Principles, Physiological Rationale, and Evidence-Based Applications | Chapter 7 | Newer Frontiers in Urology, Volume III

 

Background: Retrograde intrarenal surgery (RIRS) is a cornerstone for managing renal calculi <2 cm, yet it faces limitations including elevated intrarenal pressure, suboptimal stone clearance, and infectious complications. The integration of suction, particularly via Flexible and Navigable Ureteral Access Sheath (FANS), aims to mitigate these challenges. This chapter provides a critical appraisal of the role of suction in RIRS.

 

Methods: A synthesis of current literature and technical principles was conducted to evaluate the mechanisms, clinical outcomes, advantages, and limitations of FANS-assisted RIRS.

 

Results: FANS facilitates continuous outflow of irrigation fluid, stabilising intrarenal pressure and reducing the risk of pyelovenous backflow and sepsis. It enhances intraoperative visibility and may improve stone-free rates by actively evacuating fragments. However, these benefits must be weighed against increased costs, a learning curve, and a currently limited evidence base from large randomised trials.

 

Conclusion: Suction-assisted RIRS represents a significant technical advance, particularly beneficial in cases with enormous stone burdens, lower-pole stones, or infected systems. The decision to utilise suction—"to suck or not to suck"—should be individualised, as it is not a mandatory addition for all RIRS procedures but a valuable adjunct in select clinical scenarios.

 

 

Author(s) Details

Hariharasudhan Sekar
Department of Urology & Renal Transplantation, Sri Ramachandra Institute of Higher Education & Research Chennai, India.

 

Velmurugan Palaniyandi
Department of Urology & Renal Transplantation, Sri Ramachandra Institute of Higher Education &Research Chennai, India.

 

Vivek Meyyappan
Department of Urology & Renal Transplantation, Sri Ramachandra Institute of Higher Education & Research Chennai, India.

 

Sriram Krishnamoorthy
Department of Urology & Renal Transplantation, Sri Ramachandra Institute of Higher Education & Research Chennai, India.

 

Please see the book here :- https://doi.org/10.9734/bpi/mono/978-93-47485-93-0/CH7

Mechanical Characteristics of Sand Mortar (Cinder Blocks) and Compressed Laterite Bricks (BTC) Stabilized with Cement: A Comparative Study | Chapter 1 | New Visions in Science and Technology Vol. 3

The purpose of this study is to assess the dry and wet mechanical resistances of 1520x40 cm3 sand mortar (cinder blocks) and 101428 cm3 compressed laterite mortar bricks (BTC) stabilised with cement after immersion in water. According to the experimental results, the 28-day compressive strength values of the 12 percent cinder blocks and the 10 percent cement BTCs are 2.55 MPa and 7.90 MPa, respectively. These values are consistent with the normative criteria of the Building Materials Centre (CMC) in N'Djamena (2.4MPa) and the Land Materials Research Centre (CRAterre) (5MPa). When exposed to moisture, BTC loses only 28% of its tensile strength, whereas cinder blocks lose 46%. BTC has a suction capacity of 2.50 to 5.02 g/cm2 S(1/2), while cinder blocks have a suction capacity of 6.12 to 10.90 g/cm2.S(1/2). All of these values are below than the limit given by NF P 554, which is 20 g/cm2.S(1/2). The findings show that, when using the same cement composition, BTCs are more durable and cost-effective than cinder blocks in both dry and rainy seasons. In summary, this research has demonstrated, on the one hand, the disparity in qualities that exists between sand and laterite materials through the use of a stabiliser, cement, and, on the other hand, the benefit of employing local resources.

Author (S) Details

Bozabe Renonet Karka

National Superior School of Public Works (ENSTP) of N'Djamena,Chad.

Kinet Ouinra

Civil Engineering Laboratory of the National Superior School of Public Works (ENSTP), N’Djamena, Chad.

Tomtebaye Ngakoutou Fulbert

Civil Engineering Laboratory of the National Superior School of Public Works (ENSTP), N’Djamena, Chad.

View Book :- https://stm.bookpi.org/NVST-V3/article/view/3722

Analyzing the Soil Water Characteristic Curve of an Unsaturated Soil under Low Matric Suction Ranges and Different Stress Conditions | Chapter 3 | International Research in Environment, Geography and Earth Science Vol. 7

Under low matric suction ranges and various stress conditions, this analysis aims to examine the soil water characteristic curve of an unsaturated soil. For the design of geotechnical and geo-environmental structures such as road pavements, foundations, and ground dams, accurate assessment of unsaturated soil properties is important. One of the main characteristics of unsaturated soil mechanics is water retention behaviour in soils that is used to predict stability or infiltration problems in the soil. Therefore, the unsaturated soil properties have been recorded by several experimental works, and the soil-water characteristic curve (SWCC) test has significantly contributed to the understanding of matric suction. Because conventional instruments in SWCC tests are unable to apply stress, some researchers have developed suction-controlled triaxial devices that conduct SWCC tests under different stress states. For the understanding of the hydro-mechanical behaviour of unsaturated soils, the determination of SWCCs under stress conditions such as those in the field is key. In both drying and wetting conditions, this study conducted SWCC tests of unsaturated silt soil in low matric suction ranges. Under one-dimensional and isotropic confining stresses varying from 50 to 450 kPa, the SWCCs were measured. Instead of the high air inlet ceramic disc, the micro porous membrane approach was used to control relatively low matric suction. The controlled matrix suction range was from 0 to 20 kPa. The research revealed that the measured SWCC seems to be influenced by the in-fluence of stress conditions in low matric suction ranges. Isotropic confining stress caused the specimen's void structure to become dense and soil moisture flow movement also decreased as a result. For both models, the R2 (0.99) values obtained clearly show that the fitted values and the experimental data sets are almost located around the line of perfect agreement. Obviously, the water retention activity was high, and the point of reference to the air intake value was greater. Furthermore, the study indicates that the existing methods adopted to estimate unsaturated soil properties require further improvement to take into account the impact of different conditions of stress. Perhaps the findings of this study may be helpful in providing appropriate data to clarify the combined hydro-mechanical actions of unsaturated silt soil in the practise of geotechnical engineering.

Author(s) Details

Paul Habasimbi
Graduate School of Engineering, Ashikaga University, Omae Ashikaga Tochigi, Japan.

Prof. Tomoyoshi Nishimura
Department of Civil Engineering, Ashikaga University, Omae Ashikaga Tochigi, Japan.

View Book :- https://bp.bookpi.org/index.php/bpi/catalog/book/358