Analysis of One-Dimensional Consolidation for Unsaturated Soils under Piecewise Cyclic Loading

This paper studies the one-dimensional (1D) consolidation behavior for unsaturated stratum subjected to piecewise cyclic loading. Combined with the widely accepted consolidation theory of unsaturated soils, a semianalytical method was employed to investigate the consolidation of unsaturated foundation considering piecewise cyclic loading in the Laplace domain. Furthermore, the reduced solutions were produced to perform the verification work accompanied by the results in the existing literature. Finally, a case study was conducted to explore the consolidation characteristics under piecewise cyclic loading (i.e., triangular and trapezoidal cyclic loadings). Parametric studies were carried out by variations of excess pore pressures and settlement against the ratio of air-water permeability coefficients, depth, and loading parameters. The research proposed in this paper can provide theoretical basis for the ground treatment of unsaturated soils, especially for rationally accelerating consolidation or avoiding sudden settlement.

STUDI PERTAMBAHAN PANJANG SULUR LIANA BERDAU LEBAR (Merremia peltata) DI AREAL KAMPUS POLITEKNIK PERTANIAN NEGERI SAMARINDA

The purpose of this research is to find out the increase in the length of long Liana Broad-leavedtendrils ( Merremia Peltata) in the Area of Samarinda State Agricultural Polytechnic Campus. Theresearch was conducted for 2 months in the area Campus of Agricultural Polytechnic StateSamarinda which includes preparation and marking activities of selected liana, making ajir, wrappingliana to stick where to vine, data retrieval, data processing and reporting. The data taken in this studyare: (1) Increase in the length of tendrils Liana Broad-leaved ( Merremia Peltata) that is deliberatelyallowed to creep above the surface of the ground (treatment 1st); (2) increase in the length of tendrilsLiana Broad-leaved ( Merremia Peltata) deliberately bought on stick where to vine (treatment 2nd);dan (3) the number of Liana twists on each stick where to vine.Sampling is done intentionally(purposive sampling), namely by searching for liana in campus areas that are eligible for use inresearch. The number of samples for lyanas that are deliberately left to creep above ground level anddeliberately wrapped around stick where to vine each 30 individuals. The results of the study are asfollows: (1) the increase in the length of tendrils Liana Broad-leaved (Merremia Peltata) that isdeliberately allowed to creep above the ground (treatment 1st) is the amount of increase in tendrillength 12945.10 cm and average 431.50 cm / 6 weeks;(2) increase in the length of tendrils LianaBroad-leaved ( Merremia Peltata) deliberately bought on ajir (treatment 2) is the amount of increase intendril length 12835.10 cm and average 427.84 cm / 6 weeks; and (3) the increase of Liana BroadLeaved (Merremia Peltata) in stick where to vine is the amount of 214.00 twists and an average of7.13 twists.

Impact of pasture height and herbage mass on suppression of variegated thistle in North Island East Coast hill country

Variegated thistle in East Coast North Island hill country reduces pasture and livestock productivity. To quantify the impact of increasing amounts of pasture cover (herbage mass) on this weed, variegated thistle seeds were hand-sown in autumn into pasture swards that ranged in height from 0 cm (bare ground) to 12 cm, on an East Coast property near Gisborne. Sward height was maintained by mowing without damaging the thistle plants. Increasing pasture cover reduced thistle emergence, height, diameter, biomass, survival, and seed production. By early June, 7 weeks after sowing, thistle emergence was greatest from bare ground and from maintaining a pasture at a height of 3 cm (>1100 kg DM ha-1 in autumn) and declined with increasing pasture height. By December, thistle height, diameter, biomass, flowerhead production and survival were highest in the bare ground treatment (thistle biomass ≈760 g plant-1), much lower in the 3-cm pasture height treatment (≈20 g plant-1), negligible in the 6-cm (>1600 kg DM/ha) and nil in the 8-cm (>1800 kg DM ha-1) and 12-cm (>2700 kg DM ha-1) pasture treatments (P<0.002). Maintaining pasture height of 3 cm severely reduced variegated thistle establishment, growth and flowerhead production. Results infer that grazing management strategies, such as lengthening the interval between grazing events in autumn and early winter, will increase pasture cover and are likely to severely reduce thistle establishment, growth and seed production.

The potential of using fine rock for replacing soft soil in construction of a breakwater at Chan May port

Breakwater is an important construction in Chan May port. The construction of breakwaters faces many difficulties due to the soft soil layer with a thickness of more than ten meters and located under the sea level. Breakwater is unstable as well as high of settlement. Therefore, the soft soil under the breakwater was replaced by fine rock. The results show that it is feasible to replace soft soil by fine rock when constructing breakwater in the sea. This is the basis for the design of soft ground treatment for breakwaters in Vietnam.

Compost and Black Polyethylene Mulches Improve Spring Production of Romaine Lettuce in Southern New England

Romaine lettuce (Lactuca sativa) is the most popular leafy vegetable in the United States. Organic and synthetic mulch materials are applied by farmers to reduce their weeding expenditures, manage soil temperatures, and increase the yield and quality of their crops. This study examined the impacts of using black polyethylene, compost, and shredded leaves as surface mulches in spring open field romaine lettuce by using data regarding the soil temperature, lettuce growth, and yield parameters. Mulch treatments were compared to determine effects on soil temperature, lettuce growth rates, leaf area index (LAI), yield, and plant size. Experiments were conducted in 2017 and 2019. Soil temperatures were slightly (but significantly) warmer in 2019, the plants grew more rapidly, and LAI, yield, and plant size were all significantly greater than they were in 2017. Mean soil temperatures were 18.0 and 18.9 °C in black polyethylene mulched plots, 17.7 and 18.5 °C in compost, 17.5 and 17.0 °C in bare ground, and 16.9 and 17.3 °C in shredded leaf plots in 2017 and 2019, respectively. Changes in canopy size presented a similar trend over the growing season for all treatments; shredded leaf and bare ground treatments on all measuring dates had the smallest canopy size, and compost and black polyethylene mulches had the largest canopy sizes. Black polyethylene and compost mulches had the highest LAI and yields in both years. In 2017, the bare ground treatment was similar to black polyethylene and compost mulch treatments for both parameters, and all three treatments were significantly greater than the shredded leaf mulch treatment. In 2019, the bare ground treatment was similar to the shredded leaf mulch treatment and significantly lower than the black polyethylene and compost mulch treatments. In 2017, black polyethylene and compost mulches had LAI of 7.67 and 7.37 and yields of 6.38 and 6.68 kg·m−2, respectively. Bare ground had an LAI of 7.16 and yielded 5.94 kg·m−2. Shredded leaf mulch plots had the lowest LAI (5.94) and yield (4.96 kg·m−2). In 2019, the bare ground treatment had an LAI of 7.5 and yielded 7.6 kg·m−2. Black polyethylene and compost mulches increased LAI by 1.7. Yield increased by 2.8 kg·m−2 with black polyethylene mulch and by 2.4 kg·m−2 with compost mulch. Shredded leaf mulch produced LAI and yield similar to but slightly lower than bare ground. Dry weight, plant height, and head diameter in bare ground and shredded leaf mulch treatments were significantly smaller than in black polyethylene and compost mulch treatments. The cultivar rank order was consistent across treatments in both years; ‘Ridgeline’ grew significantly faster than ‘Coastal Star’, and plants were significantly larger at harvest. Black polyethylene suppresses weeds and increases soil temperatures, thereby enhancing yields of spring-to-summer romaine lettuce under southern New England conditions. Compost mulch has similar effects on yields. Shredded leaf mulch is effective at suppressing weeds but decreases soil temperatures and yields.

Applying the Equivalent Plane Strain solution to design the soft soil improvement by vertical drains

The soft soil improvement by vertical drains (PVD, sand drains) are widely used in Vietnam. One of the methods is used for designing soft soil improvement by vertical drains is the Equivalent Plane Strain solution. To use this solution, the permeability coefficient of soil is converted into the equivalent permeability under plane strain. The paper presents the application of this solution to design soft soil improvement by sand drains at Km 3+130 Vi Thanh - Can Tho. It indicated that the settlement results of the soft ground treatment design based on Equivalent Plane Strain solution are similar to those from the Axisymmetric Condition analysis and field monitoring.