Hydraulic Fill Research Articles

Seismic Slope Stability Analysis of a Hydraulic Fill Dam

Abstract This paper presents a seismic slope stability assessment study of an inherently heterogeneous hydraulic fill dam in Texas. Extensive cone penetration soundings conducted at the dam site we...

Experimental Development of a Novel Mine Backfill Material: Foam Mine Fill

This study aims to develop a novel mine backfill material called foam mine fill (FMF). A cellular structure is achieved by incorporating a premade foam into the backfill mixture using an air-entraining agent. FMF samples were prepared with copper-nickel mine tailings and normal Portland cement. Experiments were designed to investigate the effect of binder dosage, volume of entrained air, and foam mixing time on FMF unconfined compressive strength (UCS) and dry density. Moreover, a qualitative microscopic assessment investigated the effect of foam mixing time on air bubble structure. The pore size distribution and porosity of selected samples were investigated through mercury intrusion porosimetry. Relative to reference samples without entrained air, the UCS of FMF samples was 20–50% lower. However, the concomitant lower dry density (by up to 360 kg/m3) could enhance the safety of the underground working environment, especially in underhand cut-and-fill mining where miners and machinery work beneath the backfilled stope, and lower-density fill material would minimize the adverse effects of potential backfill failure. Prolonged foam mixing time led to a significant loss in UCS and total collapse of the air bubble structure. Other potential applications for FMF are areas where there are tailings shortages and as an alternative to hydraulic fill.

Seismic response analysis of a hydraulic fill dam

The seismic response of a highly heterogeneous hydraulic fill dam was evaluated by studying the natural frequencies of the first and second modes of vibration and analyzing the crest accelerations of different two-dimensional or 2D sections of the dam when subjected to two different earthquake excitations. The existing methods for determination of the natural frequency of earthen embankment structures can only be used to analyze the structural response at small strain levels. However, during seismic events, the natural frequency of an earthen dam is significantly affected by the nonlinear material behavior exhibited by the geomaterials at high strain levels. Hence, a novel method was devised to evaluate the strain-dependent natural frequency for plane strain 2D dam sections, using a synthesized multi-sine base excitation. The degradation of first and second natural frequencies of transverse vibration for all the 2D sections followed a linear trend when plotted against the respective crest’s root mean square strain on a logarithmic scale. The slope of the degradation curve was found to depend on the constituent material properties prevalent in the individual sections. The observed variations in natural frequencies and crest accelerations of the 2D dam sections were also used to assess the suitability of using two-dimensional plane strain analyses for studying the response of a long earthen dam having variability in material properties. Results indicate that there is a considerable chance of erroneous estimation of the seismic response of such highly heterogeneous earthen dams that are conventionally analyzed using plane strain models. A 2D analysis was found to merely capture the seismic response of the individual sections of the dam as independent entities while ignoring the stiffening or weakening effect of the adjacent neighboring segments that may have different material properties.

Selection of treatment methods for soft foundation of river in a reclamation area

Several drainage channels are usually planned in the reclamation area in order to ensure the basic water surface ratio. It is necessary to conduct deep foundation treatment before the excavation of the river due to the high water content of hydraulic fill in reclamation area. Cement mixing pile method has been widely used in the treatment of river soft foundation as a method with mature construction technology, moderate overall cost and obvious treatment effect. Taking a river in a reclamation area as an example, it is recommended to adopt the cement mixing pile method to treat the soft foundation of the river after comparing the vacuum preloading method and cement mixing pile method.

Study on the Optimal Construction Method for the Compaction Method of Hydraulic Filling in Metropolitan Areas

Study on the Optimal Construction Method for the Compaction Method of Hydraulic Filling in Metropolitan Areas

LIQUEFACTION ASSESSMENT OF RECLAIMED LAND AT CENTREPORT, WELLINGTON

Observations of liquefaction-induced damage at the port of Wellington (CentrePort) provide an opportunity to evaluate the applicability of state-of-the-practice liquefaction evaluation methodologies on reclaimed land. This study focuses on the application of widely used simplified liquefaction assessment methods on the end-dumped gravelly fills and hydraulically-placed silty and sandy fills at CentrePort for the 2013 Cook Strait, 2013 Lake Grassmere, and 2016 Kaikōura earthquakes. Liquefaction assessment of the gravel reclamation poses several challenges due to its large percentage of gravel-sized particles making it difficult to obtain high-quality in situ data. The hydraulic fills at CentrePort are also of significant interest as they relate to a range of issues in the simplified engineering assessment around effects of fines and their plasticity on the liquefaction resistance. Following the 2016 Kaikōura earthquake, subsurface explorations were performed which included 121 Cone Penetration Tests (CPTs). Results of CPT-based liquefaction triggering and post-liquefaction reconsolidation settlement assessments using state-of-the-practice procedures are discussed and compared with observed liquefaction manifestation and settlements.

Model test of the combined subgrade treatment by hydraulic sand fills and soil-cement mixing piles

The combined technology of hydraulic sand fills and soil-cement mixing piles has been widely applied to urban roads near rivers. Most of the previous studies were limited to the performance and strength of the soil-cement mixing pile and the effect of strengthening the foundation, which ignored the influence of pile layout on soil property parameters. Through laboratory model tests, various working conditions of hydraulic sand placed on a composite foundation were simulated, and the effects of rolling path, standing time, rolling machinery, drainage scheme, pile spacing and pile diameter on stress distribution and consolidation drainage of composite foundation under single variable were investigated in this paper. The test results indicated that the increase in pile diameter can significantly increase the pile-soil pressure ratio but easily causes an excessively high porewater pressure during the rolling of the subgrade. The increase in pile spacing reduces the pile-soil pressure ratio, promotes the drainage efficiency and restricts the pile group effect. Smooth-wheel rolling has a large influence on the stress path and leads to the soil arching effect in the foundation. Reasonable design of pile diameter, pile spacing and proper selection of rolling method are of great significance to improve the efficiency of subgrade reinforcement and reduce postconstruction settlement.

К ВОПРОСУ ЗАЩИТЫ ПОЙМЕННЫХ ЗЕМЕЛЬ ОТ ПАВОДКОВЫХ НАВОДНЕНИЙ

There are considered engineering solutions on protection of flood plain – riverbed areas by means of the system of alluvial dams with a multi-level scheme of their location and a possibility of flood pass in the automated regime from the first level of the protection dam to the next. The proposed solution allows preventing from dam erosion in case of flood rising higher its crest. The authors propose a comprehensive approach to the floodplain protection from floodwater using hydro – mechanization means which includes clearing of the riverbed from bottom sediments with pump dredgers increasing its capacity and simultaneously alluvial narrow-profile dams from the bottom sediments using a device for alluvial washing,which allows alluvial narrow-profile dams with a combined profile in the form of side prisms from large fractions of soil and the middle part-from small fractions. The characteristics of the protective dam with this profile are resistant to wave impact and filtration of the dam. Calculations of technical and technological parameters carried out by the authors, as well as laboratory and field studies confirmed the possibility of using bottom sediments as a building material for construction of narrow-profile dams by the hydraulic fill method.

Assessing effect of dynamic compaction on liquefaction potential using statistical methods – a case study

ABSTRACTThis article is aimed at illustrating the practical use of statistical methods in geotechnical engineering. As an example, the efficacy of dynamic compaction (DC) in the mitigation of liquefaction hazard is studied through a case study of a site in the Chang-Hwa Coastal Industrial Park in Changhua County, Taiwan. Before DC, the soil at the study site, which mainly consists of a layer of hydraulic fill of silty sand to fine sand underlain by recent alluvial plains (Qa), is deemed susceptible to liquefaction. After DC, the soil at the study site is improved such that the liquefaction potential is greatly reduced. The efficacy of DC in reducing liquefaction potential is evaluated quantitatively using the statistical methods, and the effectiveness of these statistical methods, especially when used with visualisation technique, is demonstrated. This provides a basis towards risk-based communication and decision making in the setting of practical applications.

An experimental study on compressive behaviour of cemented rockfill

• Technical information and data for better optimization and design of cemented rockfill (CRF) are presented. • Strength and stress-strain behaviour of CRF are a function of the packing density of the aggregates. • CRF with coarser particles and the best grain size distribution has the highest strength. • Addition of sand can increase the strength of CRF. • A partial replacement of ordinary Portland cement with fly ash improves the strength of the CRF. Cemented rockfill (CRF) has more superior mechanical properties (e.g., compressive strength, stiffness, cohesion and friction angle) over other types of backfill material, such as cemented paste backfill (CPB) and hydraulic fill, with the same amount of binder. A comprehensive understanding of the mechanical performance of CRF is critical for effectively applying CRF technology to underground mines. In this paper, the effects of aggregate gradation, the addition of sand, and binder content and type on the uniaxial compressive strength (UCS) and stress-strain behaviour of CRF are experimentally investigated for up to 90 days of curing. The results show that CRF with coarser particles and the best grain size distribution has the highest strength over that with uniform-sized rock aggregate, and the strength of the CRF increases with increased maximum particle size of the rock aggregate. The strength of the CRF increases in proportion with the amount of ordinary Portland cement (OPC). The addition of sand enhances the strength of the CRF samples; the extent of the increase in strength depends on the sand/aggregate replacement ratio. A partial replacement (20–50%) of OPC with fly ash (FA) appears to improve the strength of the CRF samples due to the micro-filler effect, whereas a negative effect is observed when blast furnace slag (Slag) with relatively low strength activity index is used instead. Moreover, the stress-strain response of CRF is strongly influenced by the curing age, aggregate gradation, addition of sand, and binder content and type. The results of this investigation provide technical information for designing cost-effective, safe and durable CRF structures in underground mines.

Features of Hydraulic Fill Formation in Mining Water-Bearing Lignite Deposit

Overburden dumping in hydraulic fill inside mined-out open pit is discussed. Features of hydraulic filling in an open pit at a gently dipping water-bearing lignite deposit without its drainage are presented. Parameters of hydraulic fill are correlated with hydraulic filling methods. Expediency of hydraulic fill formation without a dike is specified.

Experimental Study of Uniaxial Compressive Strength (UCS) Distribution of Hydraulic Backfill Associated with Segregation

Stope backfilling with mine wastes has become a common practice in underground mines worldwide. Despite the increasing popularity in paste and rock fills, hydraulic fill made of classified mill tailings or sands remains commonly used in many mines. When such a slurried material is placed in a mine stope, a phenomenon known as segregation can take place associated with the quick drainage and consolidation of the hydraulic fill, thereby leading to a heterogeneous fill mass. While numerous publications have focused on the alleviation of segregation, there are few studies on the characterization of the distribution of geotechnical properties within hydraulic fill due to segregation. It is particularly scarce to quantify the spatial variation of the segregation and the resulting geotechnical properties after a backfill is placed in an opening. There is also a gap to quantitatively describe the degree of segregation using an appropriate expression or definition. The aim of this study is to investigate the effect of the segregation on the spatial variation of the geotechnical properties of hydraulic fill. Laboratory tests were performed with the cemented hydraulic backfill prepared with columns of different heights. The experimental results indicate that the segregation takes place and the resulting physical and mechanical properties can vary throughout the columns for samples higher than twice of the standard size. These results also indicate that the mechanical properties of a hydraulic fill obtained in a laboratory following the current practice with standard samples may not be representative of the fill mass placed in mine stopes. Expressions are proposed to quantify the degree of segregation associated with the spatial variation of particle sizes of mine hydraulic backfill.

Effects of Moisture Content and Plasticity Index on Duncan-Chang Model Parameters of Hydraulic Fill Soft Soil

In order to explore the effects of moisture content and plasticity index on Duncan-Chang model parameters K,n, C and Rf, we selected 8 groups of soft soil with water content of 69.1% - 94.3% and plasticity index of 32.2 - 54.1 for triaxial unconsolidated undrained shear test. The results show that Cuu, K and n values all showed a downward trend, and Rf variation was not obvious with the increase of moisture content. The variation rule of each parameter is not obvious with the increase of plasticity index. When moisture content is constant, Cuu and n values do not change much, K increases with the increase of plasticity index within the range of 70% - 80% moisture content, and does not change much with the increase of plasticity index when moisture content is greater than 80%, Rf has no obvious rule. When the plasticity index is constant, Cuu, Kand n decrease with the increase of moisture content, Rf has no obvious rule. The maximum value of Cuu is 20.18 kPa, the minimum is 3.72 kPa, and the maximum to minimum ratio is 5.42. The maximum value of K is 0.517, the minimum is 0.022, and the maximum to minimum ratio is 23.5. The maximum value of n is 1.198, the minimum is 0.150, and the maximum to minimum ratio is 7.99. The maximum value of Rf is 0.872, the minimum is 0.679, and the maximum to minimum ratio is 1.28.

Open Pit Mining Technologies for Watered Lignite Deposits in the Kansk—Achinsk Basin

The resource-saving technology is proposed for mining watered lignite deposits in the Kansk- Achinsk basin without drying of productive strata. The expediency of accumulation of all water inflows in mined-out area of the open-pit mine for the subsequent use in the closed production cycle is substantiated. Effectiveness of hydromechanization in selective stripping of incompetent overburden rocks with solid inclusions is determined. Parameters of a hydraulic fill placed in the mined-out area of the open pit are presented.

Исследование влияния горнотехнических условий на производительность гидрокомплекса для совместной разработки пород гидроотвалов гидромонитором и землесосным снарядом

Исследование влияния горнотехнических условий на производительность гидрокомплекса для совместной разработки пород гидроотвалов гидромонитором и землесосным снарядом

Геомеханическое обоснование отработки свиты угольных пластов на шахте им. А.Д. Рубана под гидроотвалом открытых горных работ

Геомеханическое обоснование отработки свиты угольных пластов на шахте им. А.Д. Рубана под гидроотвалом открытых горных работ

Features of Hydraulic Fill Formation in Mining Water-Bearing Lignite Deposit

Features of Hydraulic Fill Formation in Mining Water-Bearing Lignite Deposit

Прогноз устойчивости гидроотвалов на подрабатываемых подземными горными работами территориях

Прогноз устойчивости гидроотвалов на подрабатываемых подземными горными работами территориях

Conditions of hydraulic fill intrusion from mined-out stopes to current stoping area

Conditions of hydraulic fill intrusion from mined-out stopes to current stoping area

ЗАБЕЗПЕЧЕННЯ НАДІЙНОЇ ЕКСПЛУАТАЦІЇ НАФТОВИХ РЕЗЕРВУАРІВ У СКЛАДНИХ ГЕОТЕХНІЧНИХ УМОВАХ ПРИ СЕЙСМІЧНИХ ВПЛИВАХ

ЗАБЕЗПЕЧЕННЯ НАДІЙНОЇ ЕКСПЛУАТАЦІЇ НАФТОВИХ РЕЗЕРВУАРІВ У СКЛАДНИХ ГЕОТЕХНІЧНИХ УМОВАХ ПРИ СЕЙСМІЧНИХ ВПЛИВАХ