Land Reclamation Site Research Articles

Feasibility of using three solid wastes/byproducts to produce pumpable materials for land reclamation

Land reclamation is important for countries with limited land resources, and it requires a huge volume of filling materials. Traditional filling materials such as sand are depleting, which urges the discovery of new filling materials. The rapid growth of population and urbanization has also witnessed increasing solid waste generation. In this context, it is beneficial to turn the solid wastes into filling materials for land reclamation. This study, therefore, intended to reuse three solid wastes/byproducts, namely excavated marine clay (MC), incineration bottom ash (IBA), and ground granular blast-furnace slag (GGBS) to produce pumpable filling materials for land reclamation. Ordinary Portland cement (OPC) was utilized as a reference binder for comparison with GGBS. To this end, the workability (flowability and bleeding), appearance, unconfined compressive strength (UCS), mineralogy and microstructure, and leaching of heavy metals of the proposed materials were investigated. Considering the seawater exposure at land reclamation sites, the integrity of materials in water environments was examined. The results highlighted that for air-cured specimens, to achieve a target UCS of 100–200 kPa, the binder usage of IBA–MC–GGBS could be only half that of IBA–MC–OPC. In water environments, IBA–MC and IBA–MC–OPC generated cracks or were even dismantled, especially when soaked in seawater, posing a significant concern for land reclamation. However, IBA–MC–GGBS showed much higher resistance against seawater than IBA–MC and IBA–MC–OPC. The formation and growth of ettringite was the primary cause of the instability of IBA–MC and IBA–MC–OPC. The hydration of GGBS in IBA–MC–GGBS consumed alkaline minerals, which in turn suppressed the formation of ettringite. The results indicated the feasibility of using IBA–MC–GGBS as pumpable filling materials for land reclamation.

To the method of distribution drainage pipelines calculation with sloping groundwater level

A methodology for assessing the influence of the error value, which is included in the calculations of distribution pressure drainage pipelines in the case of a groundwater surface slope, is proposed in the paper. It is based on the previously obtained solutions of the system of differential equations describing the liquid movement with variable flow rate in distribution pressure drainage pipelines that operate at the horizontal level of the groundwater surface. The analysis is presented in dimensionless form. The influence of the groundwater level slope on the calculation results is estimated using the value of the relative flow variation in the initial section of the distribution pipeline and the generalized parameter of the distribution drain A, which takes into account its design and filtration characteristics. The obtained calculation formulas are quite simple and easy to use. The proposed method allows to determine the limits within which simplified dependencies for the calculation of drainage pipelines can be used, which are recommended for use at the horizontal groundwater level on the land reclamation site. At the same time, the error introduced into the calculations as a result of the adopted simplification is immediately determined. Corresponding graphs are presented in the paper to illustrate the obtained dependencies.

Between Land Reclamation and Labour, Empathy and Asian New Wave Film: Fungibility in Yeo Siew Hua’s A Land Imagined 幻土

Yeo Siew Hua's film A Land Imagined (2018) is interspersed with long scenes at a work site. The camera often rests on the droning work of machines and workers carting and sorting gravel. But for all the movement that is displayed, no change has taken place. Piles of gravel are demolished and moved to make new piles. The persons in the film appear similarly fungible: an injured laborer can become a driver, a corpse may or may not explain a disappearance. Ultimately, the site is revealed to be a land reclamation site which reveals that movement of gravel is not a closed innocuous system, but is part of a zero-sum game, in which one country grows bigger by cannibalizing those around it. Using Sadiya Hartman's work on fungibility as a lens through which I consider the modern-day ‘coolie' in the film and Lisa Lowe’s writing on immigration and citizenship, I argue that Yeo allegorizes the movement of land across bodies of water for the similar movement of indentured laborers in order to critique the invisibility of foreign low-wage labor in Singapore, at the same time that the products of their labour are put on brash display. Critics like Hartman and Lowe, whose critical interests connect exchange, labor, and transnational movement across oceans and bodies of water, offer a critical framework with which we can think about how the film takes up the racial, national, and gendered intersections of these issues. Finally, in drawing from and inserting itself within an extant body of work by Asian New Wave directors, A Land Imagined ultimately enacts an imaginative and responsible form of transnational assemblage, connecting cultures and people across oceans not through labour or even soil, but through art.

Application of Drone LiDAR Survey for Evaluation of a Long-Term Consolidation Settlement of Large Land Reclamation

Drone surveys are gaining popularity for many construction applications, including in the fields of civil engineering, such as road construction, earthwork, structure monitoring, and coastal topography analysis. Drone surveying has a high potential for periodical long-term ground settlement measurement in the field of geotechnical engineering. Traditionally, manual measurement has been performed for limited points with controlled surface measurement points, but drone surveying may enable automated and periodical measurement for a wide and remote site. However, the accuracy of the elevation measurement and the surface settlement prediction has not been investigated, and the use of drone surveying has thus been limited. Therefore, an experiment was carried out to apply drone LiDAR (Light Detection and Ranging) surveying for soft ground settlement measurement at a large land reclamation site showing a very large settlement up to 10 m. Periodic drone LiDAR surveying was conducted, and the data were processed with direct georeferencing and with outlier removals (such as trees and construction vehicles) in order to generate a clean surface point cloud. We then compared the processed elevation data with ground control data to check the vertical accuracy and to predict the settlement as well as for consolidation. The drone LiDAR survey showed 13 cm, 42.9 cm, and 6.23% differences in RMSE (Root Mean Square Error) in terms of vertical accuracy, predicted long-term settlement, and consolidation, respectively. The drone LiDAR accuracy seems very useful for monitoring settlement over a large and remote land reclamation site of soft ground, showing settlement up to several meters where, without a surface measurement, installment is limited.

Decision-support for land reclamation location and design choices in the Maldives

Land reclamation in the Maldives is widespread. Current land reclamation practices, however, lack a systematic approach to anticipate sea-level rise and do not account for local flood risk differences to inform location and design choices. To address these limitations, this paper applies two decision-support tools: a hazard threshold analysis, and a cost-benefit analysis. Both tools produce site-specific estimates of land elevations or flood defence heights but do so for different goals. The hazard threshold analysis identifies hazard-based solutions that meet an acceptable flood probability for an intended lifespan without follow-up actions by reliability optimisation. The cost-benefit analysis identifies risk-based solutions using dynamic programming. We apply both tools to two land reclamation sites, a newly reclaimed airport island and a land extension of an inhabited island, in the Maldives. We find that total hazard-based heights for long-term planning horizons are highly uncertain, with local height differences of up to 1.9 m across sea-level rise scenarios by 2100. Risk-based Island elevations, in contrast, differ much less across scenarios, offering a practical advantage for decision-making. However, land reclamation choices on location, land elevation and investment in flood protection are not only driven by hazard-related aspects, such as reef characteristics, swell exposure, and sea-level rise, but also by estimates of exposed assets, reclamation, and flood protection costs. Taken together, the two decision-support tools are helpful for improving adaptation decisions and are also applicable in other small island regions.

Assessment of the slope influence on the pressure collecting drainage pipelines characteris-tics

A methodology for assessing the influence of the error value, which is included in the calculations of pressure drainage pipelines in the case of a groundwater surface slope, is proposed in the paper. It is based on the previously obtained solutions of the system of differential equations describing the liquid movement with variable flow rate in pressure drainage pipelines that operate at the horizontal level of the groundwater surface. The analysis is presented in dimensionless form. The influence of the groundwater level slope on the calculation results is estimated using the value of the relative flow variation in the end section of the collector and the generalized parameter of the collector drain A, which takes into account its design and filtration characteristics. The obtained calculation formulas are quite simple and easy to use. The proposed method allows to determine the limits within which simplified dependencies for the calculation of drainage pipelines can be used, which are recommended for use at the horizontal groundwater level on the land reclamation site. At the same time, the error introduced into the calculations as a result of the adopted simplification is immediately determined. Corresponding graphs are presented in the paper to illustrate the obtained dependencies.

Dynamic compaction of crushed concrete fill, full-scale test at Jätkäsaari, Helsinki

Concrete waste in the form of crushed concrete can be utilized in street and road structures. Today, a significant amount of concrete waste generated by various demolition and other activities is not fully utilized in infrastructure projects within Helsinki; as a result, a portion of concrete waste generated in the city is be transported to other sites outside the Helsinki metropolitan area. In Helsinki, large-scale land reclamation projects have been implemented, and this trend will continue in the near future. Utilization of concrete waste as fill material in land reclamation projects will reduce the need to transport concrete waste outside the Helsinki metropolitan area, with a concurrent reduction in need to transport blasted rock to the land reclamation sites. This will promote reuse and recycling of waste and will reduce heavy traffic and CO2 emissions. Crushed concrete has not been previously tested in Finland as a fill material in land reclamation projects subjected to deep compaction methods. In 2018-2019 suitability of crushed concrete for land reclamation purposes was tested in a full-scale dynamic compaction test. The objective of the test was to assess the degree of compaction produced by dynamic compaction, determine the compression rate of compacted layers under pre-loading embankment, and measure environmental impacts of the fill material. The pilot structure was implemented in Tritoninpuisto (Triton Park) located in the southern part of Jatkasaari. Crushed concrete with varying grain size was compacted using the dynamic compaction method. All materials compacted well. Results of the pilot study indicate that dynamic compaction can be applied to densify crushed concrete fill material for land reclamation. Settlement plates on the top and the bottom of the pilot structure were used to monitor short-term settlement during dynamic compaction and long-term settlement after completion of the work. Long-term settlement was minor after compaction and placement of a pre-loading embankment. Implemented study has indicated that compacted crushed concrete is a suitable material for land reclamation in street and park areas.

Evacuating offshore working barges from a land reclamation site in storm emergencies

This paper investigates a barge evacuation planning problem (BEPP) that can arise during land reclamation projects. The problem was motivated by the issue faced in actual practice by the Hong Kong International Airport (HKIA). In this problem, a fleet of heterogeneous barges working at an offshore land reclamation site needs to be evacuated to coastal shelters prior to the arrival of a storm. Having no propulsion power of their own, these barges must be towed by tug boats in order to be evacuated. The problem under consideration is very complicated since it involves a series of inter-correlated assignment and scheduling decisions at different planning levels. To solve the problem, this paper first formulates the problem as a nonlinear Mixed Integer Programming (MIP) model. The model is then linearized. We further proved that the BEPP is NP-hard in the strong sense. In view of the complexity of the problem, a tailored heuristic method is proposed. Extensive numerical experiments and a case study are performed, and the results demonstrate the effectiveness and efficiency of the solution method. Land reclamation projects have become increasingly popular in recent years, and the proposed method is applicable to solving BEPPs arising in similar scenarios.

Vibro-compaction at a land reclamation site in Phuket, Thailand

Phuket is the biggest island province in Thailand. Located in the southern part of the country, this island is famous and a favourite destination for foreign and Thai tourists alike. Consequently, this province continually develops with booming tourism and hence there is a need for large and advanced infrastructure. Construction projects are increasing each year, but the available land area is limited and land reclamation has therefore become an alternative. Sand backfill material is available on the island. However, the loose sand fill needs to be densified for structural support or structural foundations, and the ground improvement technique called vibroflotation is suitable for improving the sand density in a small area over a short period. This paper presents an assessment of the effectiveness of vibroflotation in the densification of sand fill, which was applied for the first time in Thailand. The standard penetration test values of the sand fill before and after improvement were compared, evaluated and confirmed with regard to liquefaction susceptibility during earthquake occurrences. It was confirmed that the vibroflotation technique can increase the density of sand fill in land reclamation and can increase its bearing capacity as well as prevent liquefaction during earthquakes.

Shifts in reclamation management strategies shape the role of exopolysaccharide and lipopolysaccharide-producing bacteria during soil formation.

SummaryPolymeric substances produced by microbes play a key role for the development of soil aggregates. Here, we investigated the dynamics of bacterial families contributing to the formation of exopolysaccharides and lipopolysaccharides, major constituents of polymeric substances, at a managed land reclamation site of a post‐mining area. We collected soil samples from the initial and the agricultural management phase and expected a peak in the abundance of bacteria capable for exopolysaccharide and lipopolysaccharide production at the points of the biggest disturbances. We used shotgun metagenomic sequencing in combination with measurements of exopolysaccharide concentrations. Our results underline the importance of exopolysaccharide and lipopolysaccharide‐producing bacteria after nutrient input combined with structural disturbance events, caused here by the initial planting of alfalfa and the introduction of a tillage regime together with organic fertilization in the agricultural management phase. Moreover, the changes in management caused a shift in the exopolysaccharide/lipopolysaccharide‐producing community. The initial phase was dominated by typical colonizers of oligotrophic environments, specifically nitrogen fixers (Rhizobiaceae, Comamonadaceae, Hyphomicrobiaceae), while bacteria common in agricultural soils, such as Sphingomonadaceae, Oxalobacteraceae and Nitrospiraceae, prevailed in the agricultural management phase.

Experimental study on a dredged fill ground improved by a two-stage vacuum preloading method

The vacuum preloading method has been wisely chosen among many ground-improvement methods considering the time limit of many projects and the characteristics of reclaimed soil. However, the loss in vacuum with soil depth, the clogging around prefabricated vertical drains (PVDs), and the deteriorative consolidation of the deep soil layer, among other factors, create a large challenge to vacuum preloading for dredged marine clay fill. Thus, this study proposes a two-stage vacuum preloading method and focuses on its feasibility and effectiveness. Contrasting laboratory tests are performed in two identical experimental tanks with dredged marine clay fill from the Wenzhou land reclamation site in China. In one tank, the one-stage vacuum preloading method is used to serve as a baseline for this study. In the other tank, use of the two-stage vacuum preloading method is proposed for consolidation; it comprises two stages. In the first stage, the dredged marine clay fill is conditioned by vacuum preloading using half of the PVDs, where the dissipation of the excess pore water pressure tends to be steady. In the second stage, vacuum preloading is activated using all the PVDs. The results show that a better consolidation effect is achieved with the proposed method in terms of the settlement, vacuum pressure, pore water pressure, water content, vane shear strength, and soil particle microstructure after soil consolidation.

Pilot tests on vacuum preloading method combined with short and long PVDs

Dredged marine clay has been widely used as a filling material for land reclamation in China. The difficulty of using the vacuum preloading method to improve the dredged marine clay together with the bottom sediment clay is the different spacing requirement of the PVDs. To solve this problem, the Vacuum Preloading method combined with the Short and Long PVDs (VPSL) is proposed in this paper. The short PVDs are installed only into the dredged marine clay layer in-between the long PVDs which are installed through the whole clay layer. Pilot tests are also conducted at a land reclamation site in Tianjin, China, to investigate the performance of the proposed method. The ground settlement, the applied vacuum pressure and the pore water pressure in the soil are monitored during the pilot tests. The average degrees of consolidation are calculated based on the monitored settlement and pore pressure data. It is found that the proposed VPSL method is more effective for improving top dredged clay together with the bottom sediment clay than the conventional vacuum preloading method. The vane shear strength profiles of soil layers after ground improvement also show that the VPSL method is more effective to achieve a uniform soil strength profile.

Pilot tests on methods to form working platform on soft clay

Pilot tests on the usage of vacuum preloading combined with short prefabricated vertical drains (PVDs) to form a working platform for future soil improvement work were conducted at a land reclamation site in Tianjin, China. The short PVDs were connected using three methods – the conventional vacuum preloading method, fish-bone connectors and embedded horizontal pipes. To investigate the influence of PVD spacing, short PVDs were installed in square grids with spacings of 0·4 m and 0·6 m. The ground surface settlement, pore water pressures, water content and undrained shear strength of the soil were measured during the specific period of vacuum preloading. The pilot tests indicated that short PVDs connected using embedded vacuum pipes installed at 0·4 m spacing were the most suitable method to form a working platform on the surface of the dredged marine clay. This method yields a substantial saving on construction cost and time while exhibiting similar efficiency to the conventional vacuum preloading method. The undrained shear strength and degree of consolidation of the soil after 60 d of vacuum preloading were 23·6 kPa and 85·1%, respectively, which met the requirements for the working platform.

Laboratory investigation of electro-osmosis effects in saturated dredger fill—a comparison with the stack preloading

ABSTRACTA set of unconventional electro-osmosis (EO) experiments using intermittent current was conducted on dredger fill samples from a land reclamation site at Liaoning Coast in China. This study focused on the quantitative evaluation of the use of EO to enhance the effect of surcharge preloading consolidation, thus improving the mechanical and physical properties of soil. The sand wells were used to avoid excessive consumption of electrical energy in the process of repeated seepage. A systematic comparative study on preloading combined with electro-osmotic consolidation shows that the EO coefficient decreases with water content. The increase in shear strength at a potential difference of 15 V combined with a loading of 2.67 kPa is approximately twice as high as that of preloading only, but the electrical power consumption is merely 23% more. Mercury injection tests and scanning electron microscopy images showed that the subsidence mechanism of Liaoning Bay soil is the change of macropores to mesopores. Furthermore, using the combined method of EO and preloading results in even treatment effects in different soil depths. Electrochemical reaction and economic benefit are further analyzed. All of these results indicate that combining preloading and EO ensures better performance than individual operation.

A pilot test on a membraneless vacuum preloading method

A membraneless vacuum preloading method is proposed in this paper for soft soil improvement. The method offers several advantages over the conventional vacuum preloading in which membrane is used to create the airtight condition and sand blanket layer to distribute vacuum. To assess the effectiveness of the proposed method, a pilot test was conducted at a land reclamation site in Tianjin, China. The ground settlement and the pore water pressure (PWP) at different elevations in soil were measured. After vacuum preloading, the average water content of the soft soils reduced by approximately 12% and the undrained shear strength increased twofold. The average degree of consolidation at the end of the vacuum preloading achieved 85.1% based on the settlement data and 84.5% based on the PWP data. The pilot test data have shown that the proposed method exhibits similar efficiencies to the conventional vacuum preloading method.

Geochemical characterization of engineered coal-combustion byproducts (CCBs): Occurrence and mobility of trace elements, implications for interactions with acidic and ambient groundwater

Fixed scrubber sludge (FSS), is a coal-combustion byproduct composed of flue gas desulphurization sludge, fly ash, and quick lime. FSS has potential usages as structural fill and capping materials in mine land reclamation because of its low permeability and acid-neutralization capacity. Sediment cores extracted from an abandoned mine land reclamation site where FSS was used as a hydrologic barrier to groundwater recharge were analyzed in an effort to quantify the chemical phases (both primary and secondary) that constitute the FSS, and to evaluate any evidence of weathering that has occurred during the 18years since emplacement. The primary solid phase is amorphous spheroids. Four different types were identified and their quantitative compositions were obtained, with SiO2, Al2O3, and FeO being the primary components. Of special concern was the occurrence and mobility of trace elements within the solid phases. Sequential extractions using different chemical reagents were conducted to analyze the concentrations of As, B, Ba, Cd, Cr, Cu, Ni, Pb, and Zn in different fractions as indications of mobility. The highest concentration of the trace elements was contained in the residual fraction, which is consistent with the amorphous spheroids being very resistant to chemical weathering. The results also suggest that the mobility of the trace elements decrease in the following order: B, Cu>Cd, Zn, Pb, Cr>Ba>Ni>As. Comparison of samples collected from the weathered edges and unweathered portions of the FSS layer reveal that a more aggressive weathering environment exists at the upper boundary of the FSS, where it is in contact with oxygenated soil water. The quantitative chemical compositions, distribution of trace elements, as well as evidence of how trace elements are released provide background data for the development a reactive transport model to simulate long-term effects of placing FSS in the natural environment; and particularly in areas that are being subjected to abandoned mine land reclamation.

인천국제공항 식재기반 구조 및 토양특성 연구

This study aims to suggest adequate soil management through the analysis of physicochemical properties of soil in the planting grounds of Incheon International Airport, which was constructed on a massive land reclamation site. Study areas were 5 sites at the international business complex, the passenger terminal, the airport support complex, the free trade zone, and the access road. Soil profile analysis showed that 9 plots out of the 27 plots were hardpan and heterospere within 80cm from the soil surface. The earth laid on the ground was categorized as gravel based soil(4 plots), dredged soil from the sea bottom and mixed reclamation materials(2 plots), clay with poor permeability(3 plots) and waste construction material(1 plot). Average soil hardness was and soil textures were sandy soil, sandy loam and loamy sand. Average soil pH was 6.7 and average organic matter content was 0.7%. Electrical conductivity was 0.0dS/m and exchangeable cation concentrations were 3.4cmol/kg, 1.5cmol/kg, 0.3cmol/kg and 1.0cmol/kg. Average cation exchange capacity was 11.0cmol/kg. Although average figures in Solum mostly meet the landscape design criteria, properties of each soil layer showed various values sometimes over the limit. Base saturations were 29.9%, 13.3% and 3.7% for lower soil, 33.3%, 17.0% and 2.7% for mid-soil and 32.6%, 12.2% and 1.9% for upper soil. Exchangeable sodium percentages were 16.4% for lower soil, 7.5% for mid-soil and 4.7% upper soil. Sodium adsorption rates were 0.8 for lower soil, 0.3 for mid-soil and 0.2 for upper soil. Factors affecting to the vegetation growth were heterogeneity and poorness of solum, disturbance of dredged soils, high soil hardness including hardpan in the subsurface soil layer and shallow effective soil depth, high soil acidity, imbalance of base contents, low organic matter content and low available phosphate levels in the soil.

Enhanced Phytoextraction of Heavy Metals from Contaminated Soil by Plant Co-cropping Associated with PGPR

In this study, 1-year greenhouse pot experiments were conducted to investigate the effect of Phyllobacterium myrsinacearum strain RC6b on the growth and phytoextraction efficiency of heavy metals by a Zn/Cd hyperaccumulator (Sedum alfredii) and alfalfa (Medicago sativa L.) in a co-cropping system. The treated soil sample was collected from a land reclamation site of Pb/Zn mine tailings in Hanzhong City, Shaanxi Province, China. Results showed that, with the inoculation of RC6b, shoot biomass yields of plants were significantly increased by 15.9–20.2 % and 17.2–19.9 % for alfalfa and S. alfredii, respectively, compared to the non-inoculated plants. Biomass yield of alfalfa was higher than that of S. alfredii. RC6b inoculation increased metal concentrations by 18.6–31.2 % (Pb), 23.8–37.5 % (Cd), and 26.4–38.3 % (Zn) in S. alfredii shoots, and by 13.8–24.7 % (Pb), 15.8–26.6 % (Cd), and 24.8–35.6 % (Zn) in alfalfa shoots, respectively. After six consecutive harvests of shoots, RC6b inoculation increased the phytoextraction efficiencies of Pb, Cd, and Zn by shoots of the co-planting system by 16.9, 46.3, and 60.9 %, respectively. Nevertheless, phytoextraction of Cu was not improved by RC6b inoculation. In the co-planting/inoculation system, the percentage removals of metals from soil by the plant shoots were 6.09, 30.97, 11.10, and 1.68 % for Pb, Cd, Zn, and Cu, respectively, after six harvests of shoots. Inoculation with RC6b significantly increased the soil microbial activity and the carbon utilization ability of the soil microbial community.

Perspective of the Kenyaʼs Paddy Fields from a Land Reclamation Site in Japan

Perspective of the Kenyaʼs Paddy Fields from a Land Reclamation Site in Japan

Soil and plant response to unused potassium silicate drilling fluid application

Drilling fluid, also referred to as drilling mud, is a major waste from oil and gas drilling. Land application is a novel approach to potassium silicate drilling fluid (PSDF) waste recycling, addressing its disposal requirements while potentially improving soil quality for land reclamation. Inorganic nitrogen (N) and phosphorus (P) fertilizer (0, 34N: 45Pkgha−1) was added with PSDF (0, 30, 45, 60m3ha−1) as eight PSDF amendments. PSDF amendments were incorporated or sprayed on four reclamation soils (sand, loam, clay loam 1 and 2). Response to PSDF application was assessed in the greenhouse with two plant species (Hordeum vulgare L. (barley) and Agropyron trachycaulum (Link) Malte (slender wheat grass).PSDF amendments had no detrimental effects on soil quality (macronutrients, pH, salinity, sodicity) and plant growth except in clay loam 2 soil. In loam soil, barley height and biomass were greater with PSDF at 45m3ha−1 with fertilizer relative to soil without PSDF. In sand soil with PSDF at the highest rate without fertilizer, wheat grass height was 1.08 times and biomass was 1.76 times greater than the control. High electrical conductivity in clay loam 2 soil, and decreased density, height and biomass of wheat grass at highest PSDF application rates or with PSDF incorporation, suggest a threshold beyond which conditions are compromised for PSDF application. Increasing PSDF application rate increased soil potassium availability by 1.6–4.1 times relative to no PSDF. This initial research demonstrates that PSDF may be an appropriate soil amendment for agricultural crops and native plant species on land reclamation sites with consideration of substrates properties, plant species tolerances and inorganic fertilizer.