Hydraulic Fill Research Articles

ABSTRACT To address land demands from coastal urbanization, dredged sediments are increasingly utilized as landfill materials, consolidated by vacuum preloading (VP) with prefabricated vertical drains (PVD). While VP is well-established for conventional soft soils, the performance differential between PVD types in ultra-soft hydraulic fills remains poorly quantified which is characterized by high water content and fine-grained sediments (d50=0.005mm). This study evaluates VP efficiency usingPVD-A and PVD-B in 3,000 m² reclaimed plots over 160 days. Comprehensive monitoring tracked pore water pressure, surface settlement(SS), layered settlement, water content, and vane shear strength(VSS). Results demonstrated PVD-A’s superior performance, with greater SS, higher VSS, larger PWP reduction, lower consolidation degree, and higher water content. This improved performance may be attributed to PVD-A’s lower longitudinal discharge capacity, which reduced fine particle migration and clogging during early consolidation stages, thereby sustaining drainage efficiency long-term.These findings of PVD-A’s advantage are valuable for optimizing VP design in reclamation projects.

Centrifuge and Numerical Investigation of Loose Hydraulic Fill Supported by DCM Columns

Tailings facilities of large mining and processing plants are particularly responsible structures the destruction of which can cause serious environmental and socio-economic consequences. One of the factors affecting the safety of the operation of such facilities is strong seismic effects caused by earthquakes of tectonic and technogenically induced nature. Tailings facilities are technogenic facilities that significantly change the engineering, geological and landscape situation of territories. Anthropogenic changes in the geological environment associated with the construction and operation of tailings facilities also significantly affect local changes in seismicity. When increasing the volume of tailings facilities, low-velocity, waterlogged technogenic soils are located at the base of the enclosing dams of subsequent tiers. When designing these structures, it is necessary to consider the possibility of soil liquefaction at their base. The paper discusses the results of testing approaches to assessing seismic liquefaction of technogenic soils using geophysical data in the conditions of tailings dumps of mining and processing plants of the Kryvyi Rih Iron Ore Basin. It is shown that the main geophysical factors that determine the possibility of liquefaction are the values of predicted peak horizontal accelerations of the soil surface and the law of change shear waves velocity with depth. The depth of the studied point in the section also makes a significant contribution. For points located below the groundwater level (GWL), variations in the position of the GWL and soil density above and below the GWL (for physically real situations) affect the liquefaction potential significantly less than the factors listed above. The prospects for geophysical assessment of the dynamic stability of soils of technogenic objects are substantiated. This approach was first tested on the territory of tailings dumps of mining and processing plants in Ukraine. We will consider the results obtained by the authors of the assessment of the possibility of seismic liquefaction of low-velocity technogenic soils based on borehole and field seismic surveys at one of the tailings dumps in Kryvyi Rih. The approach used is a promising alternative or addition to approaches based on penetration properties and will significantly increase the reliability of the forecast of the possibility of liquefaction of technogenic soils in the event of dynamic impacts of various nature.

Seismic response characteristics and liquefaction risk of artificial island with saturated hydraulic fill coral sand

Reclamation from the sea is a method of expanding urban area, but it also faces the problem of difficult treatment of soft soil foundation by hydraulic reclamation. Therefore, a soft soil consolidation method that combines vibration pressure boosting drainage and piled-load static pressure stacking is now proposed. To verify the effectiveness of this method, a consolidation test based on soft soil samples was designed and conducted in the study. The test results showed that when the sampling height was 240mm, the overall moisture content of the consolidated soil sample was the highest, 44.3%, and the consolidation effect was the worst. When the sampling height was 140mm, the overall moisture content obtained from the test was the lowest, 43.1%, and the consolidation effect was the best. The displacement of corner 2 and center point at the intersection of the preceding and following periods was greater, with values of 37.1 mm and 39.2 mm, respectively. At this point, the displacement of corner 1 was significantly smaller, at 30.9 mm. In the later loading stage, the slope of the vertical displacement curve significantly increased. When the experimental time reached 7000 min, the mixed method designed in this study had a drainage rate of 0.53 ml/min, which was significantly higher than other traditional methods. The experiment outcomes indicated that the method designed in this study had certain application potential for improving the consolidation effect of soft soil foundation in hydraulic fill sites.

This paper examines the effects of collapsible soil structure on shear wave velocity. The study attempts to simulate hydraulic fill sand deposits, which represent a natural soil deposition process that can result in a collapsible soil structure. A series of resonant column tests and bender element tests on Ottawa sand was conducted on sand specimens and prepared by dry pluviation and simulated hydraulic fill methods subjected to various confining pressures. Shear wave velocities measured from both methods of deposition are compared and discussed. Results from this study show that for soil specimens with the same void ratio, samples prepared by simulated hydraulic fill have a lower shear modulus and shear wave velocity than the specimens prepared by dry pluviation, and the differences are more pronounced at higher confining pressures. The resonant column test results performed in this study were consistent with results from the discrete element analysis, full-scale testing, and centrifuge testing. The discrete element analysis suggests that soil fabric and number of particle contacts are the key factors affecting the shear wave velocity. These factors are dependent on the methods of deposition. Results from this study examining hydraulic fill collapsible structure shear wave velocity provide a step forward toward a better correlation between soil dynamic properties measured in field and laboratory tests.

Settlement prediction of shallow foundations for quality controls of sandy hydraulic fills

Backfilling material such as tailing (mine wastes) mixing with cement or gypsum has grown throughout the world’s underground mines. However, despite their growing popularity, the typical hydraulic and mechanical fill types utilized in many mines still exist. Deep underground mining has increased due to the lack of commercial minerals nearby. Mine wastes were considered the main part of backfilling to prevent environmental pollution, ground subsidence after mine abandonment, and mine collapse during deeper extraction phases. The cemented backfill technique is the principal technique used in underground mines, which include cement with fly ash and/or filter dust, cement with tailing material and fly ash, gypsum with fly ash, and synthetic anhydrite with fly ash and have been reviewed. It has concluded that a backfilling material must be selected based on further goals, available material near the mine site, and economic factors. This paper analyzes different backfill material mixtures to create a technique that will increase safety in underground mining conditions and foresees an appropriate formula that gives high uniaxial compressive strength. The multiple linear regression (MLR) on the collected data from the experimental works to construct the relationship between the uniaxial compressive strength (UCS) of the mixture and the components of the backfilling and the prediction formula for expected compressive strength was obtained. The results revealed that the predicted regression equation was robust and reliable to predict the (UCS) for the new components of the filling (cement (CE), filter dust (FD), water content (WC), and time (T)).

In Peru, socio-environmental conflicts related to the development of mining-metallurgical processes and the responsible disposal of mine tailings have become central issues for accepting mining projects, especially regarding building relationships of trust with the communities. This condition has prompted the Peruvian mining industry to advance in managing alternatives to the conventional surface disposal of mine tailings. A promising and increasingly popular management strategy for mine tailings in Peru is their disposal inside underground mines. This article presents: site-specific conditions, advantages/disadvantages, and lessons learned from practical experiences of mine tailings disposal in underground mines in Peru. In addition, some techniques are highlighted, such as (i) hydraulic fill, (ii) cemented hydraulic fill, and (iii) cemented paste backfill. Finally, this article concludes that the responsible disposal of mine tailings in underground mines is a green mining solution that reduces negative socio-environmental impacts, limiting the generation of acid rock drainage (ARD) and the leaching of metals due to the decrease in contact with oxygen and rainfall, thus mitigating the contamination of surface and underground waters, reducing the footprint of affectation in the territory, and eliminating the emission of particulate matter in the environment.

Coral sand foundation formed by hydraulic fill often faces the problem of poor bearing capacity. This paper proposed for the first time to apply CFG pile composite foundation to coral sand sites to verify the feasibility of this scheme and understand its mechanical characteristics. Firstly, taking on-site coral sand as the research object, a pile sand interface shear test was conducted to clarify the mechanism of pile side friction. At the same time, the ultimate bearing capacity of CFG pile and its composite foundation was measured through in-situ static load tests. Then, based on the strength parameters of the pile sand interface revealed by indoor tests, numerical simulations were conducted to analyze the bearing characteristics of CFG piles and their composite foundations. Finally, a method for calculating the vertical bearing capacity of rigid piles in composite foundation considering interface parameters was proposed. The results showed that the bearing capacity characteristic values of single pile and composite foundation meet the design requirements; The interface friction angle and cohesion together increased the ultimate side friction by 64.41%; The load is mainly borne by the pile tip resistance, and the increase of the interface friction angle will make the proportion of the side friction load first increase and then decrease more obviously; The pile soil stress ratio first increased and then tended to stabilize as the interface strength increased. Compared with the field static load test results, the rationality of the calculation method for composite foundation rigid piles was verified. This study may have reference significance for the design and construction of coral sand foundation treatment in offshore island and reef projects.

Geotechnical Visualization and Three-Dimensional Geostatistics Modeling of Highly Variable Soils of a Hydraulic Fill Dam

In this study, a 3D numerical model, considering the dynamic interaction between soil, pile foundation, and super structure, and the parameter analysis of internal force response of pile group foundation under differences seismic intensity, was established based on the Bangladesh sewage treatment plant project to investigate the dynamic response of pile group foundation of liquid-containing structures. The results show that the internal force of pile gradually increases with time, and the horizontal dynamic displacement peak value appears earlier under different seismic wave responses and seismic intensity. With the increase of seismic time history, the variation degree of dynamic impedance with frequency and impedance peak will increase. The pile group effect and single pile bearing capacity of foundation in hydraulic fill fine sand and silty clay were verified. By comparing numerical simulation and theoretical calculation, the results show that the pile group foundation exerts the soil squeezing effect after pile construction is completed, and the dynamic elastic modulus of the soil layer can be increased. Simultaneously, the soil layer will have a better integral stiffness. The pile group effect coefficient obtained by the solid perimeter method is most consistent with the numerical simulation method.

A pile testing programme in Tuas Racetrack, South-west Singapore, involved installing 600-mm diameter 30 m long, closed-toe, spun piles by jacking (press-in system) through about 10 m thick loose hydraulic sand fill and 20 m of marine clay, sandy silt, and into weathered mudstone. Static cone penetrometers soundings, CPTU, were pushed both before and after the pile installation at each pile location and two distances away from the test pile. The post-test CPTU soundings showed that the press-in installation resulted in significant increase of cone resistance in the sand fill even at several pile diameters away from the piles. No similar effect occurred in the natural soils.

Influence of fines on the monotonic and cyclic shear behaviour of volcanic soil “Shirasu”

Effect of geomaterial variability on seismic response analyses of earthen dams

The use of sand-key reclamation works in soft and very soft soils to increase the stability of the bund construction. Reclamation using the hydraulic fill method requires a stable embankment structure to withstand the potential for landslides from landfills, and in sea areas with very soft subgrade soils, with small undrained cohesion values causes the bund to be unstable and do not exceed the critical limit. The purpose of this study is to evaluate the improvement of soft soil in bund construction so that it is stable using GeoStudio. The Bund stability analysis results show that the value of the sand-key depth depends on the variation in the depth of the seabed. At a seabed depth of -6 m, there is a sand-key depth of 7 m, -5 m the sand-key depth of 10 m, -4 m thesand-key depth of 10 m, -3 m the sand-key depth is 5 m. The final safety number of 1.404,1.438,1,675, and 1.354 respectively.

Safety of operating conditions is the paramount objective in any mine design, planning, construction and performance. In the Kursk Magnetic Anomaly, the emphasis is laid on the integrated and efficient protection of surface and underground mines from groundwater inflows. Stoilensky iron ore field hydrogeologically adjoins the northeast of Dnepr–Donets artesian basin which is contiguous to the southwest slope of Voronezh crystalline massif. The field mostly occurs in the zone of damaged groundwater dynamics under the impact of drainage facilities at opencasts of Lebedinsky and Stoilensky GOKs (Mining and Processing Plants) and at Gubkin Mine, hydraulic fills and tailings ponds of operating processing factories, and Stary Oskol water storage basin. The adversities of groundwater catchment inside sand pit wall rock mass are analyzed. The capabilities of a pit wall drainage system in stabilization of sand permeability are discussed. The experience gained in design and construction of a local drainage system based on Ranney-type well within the limits of Novaya station of an operating opencast is summarized.

Model uncertainty is present in many engineering problems but particularly in those involving geotechnical behavior of pile foundation. A wide range of soil conditions together with simplified numerical models makes it a constant necessity to review the accuracy of the predictions. In this paper, the outputs of some seventy (70) pile axially-loaded tests have been reviewed with a classic numerical model to assess pile deformation. Probabilistic approach has been used to quantify uncertainties coming from soil tests, statistic uncertainty and also from the model itself. In this way, a critical review of the prediction method and a way to quantify its uncertainty is presented. The method is intended to be used in a wide range of engineering problems.

Hydraulic-fill structures with free flow of pulp have a flattened transverse profile, especially in cases of hydraulic fill of the structure into water. The flattened profile of the structure demands significant financial and labor costs for its construction, reducing the efficiency of the hydraulic-fill structure. This paper deals with the existing methods for the construction of narrow profile hydraulic-fill structures, their economic indicators; the designs of hydraulic-fill structures using geosynthetic materials developed by the authors, which make it possible to increase their efficiency in comparison with previously known methods, especially when the structures are hydraulically filled into water.

There are large areas of soft clay distributed in coastal areas of China, which are often used as raw materials for hydraulic fill engineering in recent years, and its sedimentation characteristics have attracted more and more attention. In this paper, the influence of initial water content on the sedimentation characteristics of soft clay is studied through the experiment. The results show that: (1) the sedimentation process of soft clay can be divided into two stages: sedimentation stage and self weight consolidation stage. The sedimentation stage has a short time, and the soil property index tends to be stable quickly; the self weight consolidation stage is very slow, and the soil property index almost has no change; (2) the larger the initial water content of soft clay, the greater the sedimentation rate and the faster the sedimentation; (3) the higher the initial water content, the faster the sedimentation, the higher the water content and the void ratio, the smaller the density.