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Purpose While well-designed drainage systems could improve crop growth and yield by mitigating waterlogging and salinity stresses, field evidence of the yield responses to changes in plant-water relations and ion concentrations in leaves is scarce. We investigated the changes in ion concentrations in leaves and plant-water relations of sunflower caused by drainage in waterlogged saline soil, and their relationships to growth and yield. Methods Over two growing seasons, we tested four drainage treatments: undrained, surface drains (SD; 0.1 m deep, 1.8 m apart), subsoil drains (SSD; 0.5 m deep, 4.5 m apart) and SSD + SD. All plots were inundated (2–3 cm depth; water salinity, EC w , 1.5–2.5 dS m –1 ) for 24 h at vegetative emergence and at the 8-leaf stage before opening drains. Results Relative to the most drained treatment (SSD + SD), the undrained treatment caused higher waterlogging at 0–30 cm depth, and decreased solute potential (Ψ s ) of soil at 7.5 cm to 52–374 kPa, leaf K + by 5–20%, stomatal conductance by 5–37% and leaf greenness by 12–25%, but increased leaf Na + by 25–70%, Na + /K + ratio by 38–100% and leaf water potential by 90–250 kPa throughout the cropping season; these changes were closely related to reduced growth and yield. Conclusions The improved yield from the combination of shallow surface and sub-surface drains was attributed to an alleviation of salinity-waterlogging stress early in the season and to increased soil water late in the season that increased Ψ s and decreased Na + /K + ratio in leaves.

Waterlogging and salinity can occur together in salinised landscapes and restrict crop production. Drainage can alleviate waterlogging and salinity, but previous research suggested the need for deep drains, which may not be acceptable to smallholder farmers. Consequently, for the first time to our knowledge, we tested the usefulness of shallow drains in sunflower cultivation for smallholder farmers in a salt-affected, waterlogged coastal clay soil in the Ganges Delta. Experimental treatments were as follows: undrained, open surface drains (SD; 0.1 m deep, 1.8 m apart), slotted-pipe subsoil drains (SSD; 0.5 m deep, 4.5 m apart) and SSD+SD. All plots were inundated (2–3 cm above the soil surface) for 24 h before opening drains, at vegetative emergence and then at the V8 stage of plants. Relative to the most-drained (SSD+SD) treatment, the SD and SSD treatments gave 15–29% less yield, while the undrained treatment depressed yield by 48%. Soil water content (SWC) at 0–60 cm depth early in the season was 6–21, 4–10 and 3–5% less in SSD+SD treatment than in the undrained, SD and SSD treatments, respectively, while from flowering to harvest, SWC in SSD+SD was 2–4, 4–8 and 4–10% higher than in the undrained, SD and SSD treatments, respectively. In addition, soil electrical conductivity EC 1:5 at 0–60 cm depth in SSD+SD treatment was 31–52, 16–38 and 11–32% lower than in the undrained, SD and SSD treatments, respectively. Across all treatments, the increases in yield due to drainage were associated with decreases in waterlogging (in the 0–30 cm layer) early in the growing season, increases in SWC late in the growing season and decreases in EC 1:5 throughout the cropping season. While the shallow surface drains alone increased the yield, additional shallow subsoil drains further increased crop yield on coastal saline soils.

This South African National Road Agency project was a joint venture between consultants lngerop Africa, Letsunyane Associates and Preben Naidoo who, because of width restraints where the pavement was installed, prescribed Kaytech's Flo-drain and bidim A4 to provide efficient and long-lasting drainage. Kaytech's bidim A2 was also prescribed for use in the conventional subsoil drain sections where space restraints were not an issue. The contractors were Basil Read/Milling Techniks Consortium...

The maze of concrete-lined canals were cast onto a sand bedding layer which was underlain by a bidim A2 separation layer. Flo-Drain strips, 500 mm wide, were laid at 3 m c/c connecting to a conventional central 300 x 300 mm subsoil drain.

One of the ways to utilize manure-containing milking parlor wastewater (MPW) from dairy farms is to use it as liquid fertilizer in greenhouses. Considering that there are no clear recommendations on the disposal of manure-containing milking parlor drains by application in greenhouses, the purpose of the research was to determine the main parameters of the system for subsurface application of manure-containing milking parlor drains - perforation diameter d (mm) and pipeline depth h(mm) when growing roses in the greenhouse. The main factors influencing the process of intrasoil application of manure-containing milking parlor wastewater in a greenhouse have been identified and presented in the form of an information model. A two-factor experiment was planned, the following factors were subject to variation: perforation diameter - from 2 mm to 4 mm, pipeline depth - from 50 mm to 150 mm. The length of each pipeline option is 1500 mm, the internal diameter is 16 mm, the perforation pitch is 100 mm, and a plug is installed at the end. The supply of manurecontaining milking parlor wastewater from the tank to the perforated pipeline was carried out through flexible pipes by gravity at a rate of 6.5 liters per square meter. It has been established that the studied parameters have little effect on the length of rose stems, but have a greater influence on the number of flowers, and the diameter of the perforation of the subsoil pipeline has the greatest influence than its depth. As a result of the research, a mathematical model of the influence of perforation diameter and pipeline depth was obtained, the number of roses q was obtained, and a three-dimensional response surface was constructed. The optimal parameters for introducing manure-containing milking parlor wastewater under these conditions were perforation diameter 2 mm and pipeline depth 111 mm.

Potentiality of drain water injection in deep geological structures is investigated as a case-study of drainage system at Yakovlevsky Mine. The problem ensues from the presence of a very high zone of conductive fractures and from the very intense hydraulic connection between the water-bearing bottom coal layer and crystal ore layer due to the increased size of the mined-out space as the mine reaches the production capacity of 5 Mt, which can lead to water inrushes to underground stopes. The authors perform the predictive modeling of the joint operation of the drainage system and drain water injection to the bottom-layer water-bearing coal stratum with a view to improving safety of mining.

The aim of this study is to develop a simple analytical model for consolidation analysis of the system of clay and thin sand layers, considering the effects of the thickness of the thin sand layers and the well resistance factor simultaneously. The developed model is validated through the field data of land reclamation at the Port of Brisbane. The results indicate that as the quantity of the thin sand layer increases, the consolidation rate of subsoil layers increases due to reduction of drainage paths in the consolidation process. The increase in the thickness of the thin sand layer embedded in a thick deposit reduces the consolidation rate due to an increase in the well resistance factor of the vertical drain. The results obtained from the developed model align well with the field data. The maximum deviation in predicted consolidation degree between the cases with and without consideration of the thin sand layer is approximately 10%.

Construction on weak subsoil is a reoccurring challenge for engineers nowadays, for which various different solutions are available. Geosynthetics are getting more and more popular and one of their most widely used application is subsoil reinforcement. Several types of geosynthetics can be used, the most well-known are vertical drains and geogrids. Prefabricated vertical drains can be used for accelerating consolidation in oversaturated soils with a high water content as they drain the excess water from soil while also decreasing pore water pressure, optimizing soil bearing capacity and reducing the risk of liquefaction and excess settlements. The main limitation is not significantly reducing total subsidences. Gravel and concrete piles are widely used, and in recent years, rigid inclusions (unreinforced concrete piles) are also getting popular. A common feature of them is that a so-called Load Transfer Platform (LTP) has to be built between the superstructure and the foundation to prevent direct contact with one another. The LTP between them is a stiff, reinforced layer that helps the arching of load. Design of the LTP may be carried out using several design standards, of which the most widely used are Collin’s beam method and CUR226. This paper focuses on presenting and comparing these two main design methods, emphasizing their differences and applicability while also considering their limitations.

Colluvial deposits are commonly found throughout the Serra do Mar escarpment in Brazil. This article discusses predisposing geotechnical and geological factors related to the movement of a colluvium deposit located at km 29 of the Brazilian Federal Highway 116, Rio de Janeiro/RJ (BR-116/RJ). During the highway construction in mid-1976, an excavation of the toe of the slope was implemented, exacerbating preexisting movement. In order to understand the behavior of this deposit, field investigations, monitoring, and laboratory tests, as well as theoretical analyses were carried out. A subsoil survey in the area indicated the presence of a colluvium-filled paleo-thalweg. The site is located in a region with a specific geomorphology that favors significant sources of recharge to groundwater. The highly foliated rock has persistent parallel fractures, with a dip favorable to the groundwater flow in the direction of the slope. Statistical analyses were performed and good correlations were observed for rainfall, movements, groundwater table (GWT) levels, piezometer readings, and the discharge from deep horizontal drains (DHDs). The installation of the DHDs led to a GWT draw-down of 15 m, as well as reductions in movement and artesian pressure. The drains that presented the best performance were those installed in the colluvium-filled paleo-thalweg. Nevertheless, the present number of DHDs installed is not sufficient to permanently lower the GWT and stop the creep movement in the slope which was reactivated during a period of intense rainfall. Stability analysis indicates that a proper slope stability condition may be achieved by reducing the GWT level.

Prefabricated vertical drains (PVDs) can be installed with soil cement (SC) columns to enhance the efficiency of soft soil improvement. In this combined method, PVDs are first installed and then SC columns are established between the PVDs; this enables a larger spacing between SC columns resulting in a lower construction cost. As an embankment load is applied on composite foundation, time-dependent behavior occurs in the soft soil due to consolidation according to the radial flow toward PVDs, while the corresponding stress transfer takes place between the SC columns and the soft soil. This paper develops an axisymmetric finite element model to analyze the consolidation and stress transfer behaviors of composite foundation, in which an equivalent permeability of subsoil is proposed considering the effects of finite discharge capacity of PVDs. The developed model is applied to an embankment located in China to estimate the settlement of soft ground improved by the combined method. Subsequently, the current numerical model is applied to investigate consolidation characteristics and the stress transfer mechanism of composite foundation. The results show that the consolidation of soils can cause significant effects on the stress transfer process and the stress concentration ratio of the composite ground. The stress concentration mobilizes with the depth over time and stabilizes around the middle of the treated soil when the consolidation time exceeds 50 days. The magnitude of drain discharge capacity also contributes significantly to mobilizing stress concentration in the composite foundation.