Hydraulic Fill Research Articles

Minimizing the Volume of Water in the Settling Ponds of Hydraulic Fill Ash-and-Slag Dumps to Improve Their Operational Safety

Design and technology solutions to improve the operational safety of hydraulic fill ash-and-slag dumps by reducing or preventing the accumulation of excess water in settling ponds are proposed.

Consolidation Properties and In-Situ Stress of the Marine Clay in Southern Korea

A very soft ground constructed by dredging and hydraulic fill has characteristics such as high water content, high initial void ratio, and very little effective stress. Estimating, with thorough considerations about consolidation properties and the initial stress associated with each layer's distinctive stress history, is essential in order to predict a reasonable consolidation settlement of soft ground. By investigating a construction project for national industrial complexes at a coastal area in southern Korea that experienced reclamation and ground improvement adapting PVD, various laboratory tests to find consolidation properties were performed with undisturbed samples collected from the entire depth of the marine clay fill layer and original clay layer. Through the investigation, this report suggests relationships of heterogeneity of permeability in both vertical and horizontal directions, void ratio-effective stress, and void ratio-permeability. Considering the fact that the original clay layer was under the process of consolidation by load due to hydraulic fill from the top, estimating the appropriate initial stress of each layer is critical to predict the future process of consolidation settlement determined by time. In order to obtain the initial stresses of two layers with different stress histories related to consolidation, cone penetration and dissipation tests were conducted.

Cone Penetration Test Study of Ultra Soft Soil after Vacuum Preloading

No sand cushion vacuum preloading method is one of the construction technology for treating the ultra soft soil formed with hydraulic fill at present. The practice is ahead of the scientific research work, as the effect detection technology of the surface-layer improvement is still in the stage of exploration. In this paper, the cone penetration test (CPT) is used to detect the effect of the surface-layer improvement of the ultra soft soil based on one case in Zhejiang province in China. The result shows that the cone tip resistance is at the range of 0.08 ~ 0.40MPa and the thickness varies about 1.5 to 2.2 m of the treated ultra soft soil. The cone tip resistance along the depth has two kinds of curve shape and four zones.

Lessons From The Lives of Two Dams

Many embankment dams completed during the first six decades of the 20th century have been found deficient relative their ability to resist currently anticipated levels of seismic shaking and probable maximum flood. In this Fourth Victor de Mello Lecture, two recent case histories are described. One is a hydraulic fill structure completed in 1920 that is founded on alluvial material, some zones of which are susceptible to liquefaction. The other is a zoned earthfill dam completed in 1956 that is founded over a channel filled with loose, uncompacted, hydraulically placed tailings from gold mining operations. Each dam has been upgraded in phases over periods of several decades using different strategies and ground improvement technologies to improve stability and reduce failure risks. Several take away lessons from these experiences concerning current risk mitigation strategies, the importance of correct soil and site characterization, and implementation and effectiveness of different ground stabilization and improvement methods are presented.

Evaluation of Compressive Strength of Hydraulic Silicate-based Root-end Filling Materials

IntroductionHydraulic silicate cements such as mineral trioxide aggregate (MTA) have many clinical advantages. Newer hydraulic silicate materials have been developed that improve on the limitations of mineral trioxide aggregate such as the long setting time and difficult handling characteristics. The purpose of this study was to examine the effect of saline and fetal bovine serum (FBS) on the setting and compressive strength of the following hydraulic silicate cements: ProRoot MTA (white WMTA; Dentsply International, Tulsa Dental Specialties, Johnson City, TN), EndoSequence Root Repair Material (Brasseler USA, Savannah, GA), MTA Plus (MTAP; Avalon Biomed Inc, Bradenton, FL), and QuickSet (QS; Avalon Biomed Inc, Bradenton, FL). MethodsSamples of root-end filling materials were compacted into polyethylene molds. Samples were exposed to FBS or saline for 7 days. A universal testing machine was used to determine the compressive strengths. ResultsQS had significantly lower compressive strength than all other materials (P < .001). White MTA and MTAP mixed with liquid had lower compressive strengths after exposure to FBS compared with saline (P = .003). ERRM, MTAP mixed with gel, and QS were not affected by the exposure to FBS. ConclusionsNew silicate-based root-end filling materials, other than QS, have compressive strength similar to MTA. Within the limits of this study, premixed materials and those mixed with antiwashout gel maintain their compressive strength when exposed to biological fluids.

The Application of Bamboo Network Reinforcement Technology on Hydraulic Fill Soft-Soil Foundation Treatment

To make a large area of dredger fill silt surface layer form working face and subsequent construction problems, the project conducts the bamboo network reinforcement in the silt surface layer. It makes the surface layer bearing capacity to meet the construction requirement of deep processing. Based on Shantou Municipal Road Embankment Treatment Engineering and the project, the bamboo network reinforcement technology to reinforce the dredger fill super soft soil surface layer is used. The results show that the bearing capacity of hydraulic fill super soft soil surface layer is 32.6 kPa after 3 months treatment. The surface layer bearing capacity after 3 months treatment improved 323% than the early treatment and increased 695% than no processing. The results indicate that the reinforcement effect is outstanding and provide the basis for drafting the dredger fill super soft soil surface layer treatment plan.

3D Numerical Simulation of Elastoplastic Consolidation Process of Fly Ash Dam

The total consolidation process in the construction of hydraulic fill fly ash dam is calculated and analyzed by using the Biots consolidation theory and Cam-Clay model. Meanwhile, some problems such as characteristics of subsidence, excess pore pressure and stress of dam, influences coming from consolidation of hydraulic fill fly ash dam caused by drainage layer in dam foundation, etc, are analyzed. Results show that constructing hydraulic fill fly ash dam in saturated fly ash ground is feasible, and setting drainage layer in the dam foundation can greatly expedite the consolidation speed of dam, which is propitious to the safety of dam.

Time dependent settlements in hydraulic fills

The paper reports some experimental studies carried out on hydraulic fills, in an attempt to understand their settlement pattern which is quite different to what has been reported for clays and sands. The immediate settlement in hydraulic fills is about 60% of the total settlement, and the remaining 40% of the time-dependent settlement includes primary and secondary compression components which are difficult to separate. The inter-relationship among permeability, effective stress and settlement is also investigated. It appears that the coefficient of secondary compression Cα increases with the applied loading but is independent of time. Settlement (s) is a bilinear function of logarithm of time, taking the form of s = s0 + a log t, where s0 is approximately the immediate settlement.

Applications of Drainage Consolidation Techniques Reinforcing the Foundation of Hydraulic Mud Fill

In recent years, using the hydraulic mud fill to carry out the reclamation construction actions has been an acceptable way to settle the contradiction between the scanty lands with the rapid industrial development in coastal regions. How to improve the ultra-soft foundation made of fresh hydraulic mud fill efficiently has been the crucial issue. This paper presents three reinforcement techniques in reclamation projects, and the applications are briefly introduced.

The Study of Stabilization of Hydraulic Fill Sand and Silt Mixture in Coastal Area

In this paper, relevant experiments had been conducted on the stabilized mixture of hydraulic fill sand and silt in coastal areas, include the study of optimum mixing ratio of hydraulic fill sand and silt and the appropriate curing agent; as well as the change law for the strength of solidified sediment mixture with different curing agent content. The results show that strength of the stabilized mixture showed the highest when mass ratio of hydraulic fill sand and silt was 60% :40%, and using G2 as the curing agent. Strength of stabilized sediment mixture all increased in different degrees as the mixing amount of curing agent increased.

Centrifuge and Large-Scale Modeling of Seismic Pore Pressures in Sands: Cyclic Strain Interpretation

AbstractCentrifuge modeling of pore pressure buildup in a sand deposit as a result of shaking is evaluated by comparison with a large-scale experiment. In large-scale Test SG-1, a 5.6-m-thick, mildly sloping deposit of hydraulic fill clean Ottawa sand of Dr=40%, was subjected to 5 s of low-intensity base shaking (<0.02g) that induced excess pore pressures short of liquefaction. Three centrifuge experiments using various soil deposits and saturation fluids were conducted and compared with the large-scale test. One of these centrifuge simulations used the same Ottawa sand and Dr=40% of the prototype, a viscous pore fluid, and dry pluviation deposition, which created a soil fabric stiffer than the prototype. The other two centrifuge simulations used silty sand saturated with water. The pore pressure buildup in one of the silty sand tests was in good agreement with the prototype, while the other two centrifuge deposits did not develop any excess pore pressure. The various responses in the four tests are expla...

Effect of Hydraulic Retention Time and Filling Time on Simultaneous Biodegradation of Phenol, Resorcinol and Catechol in a Sequencing Batch Reactor

Abstract In the present study, treatment of synthetic wastewater containing phenol, resorcinol and catechol was studied in a sequencing batch reactor (SBR). Parameters such as hydraulic retention time (HRT) and filling time have been optimized to increase the phenol, resorcinol, catechol and chemical oxygen demand (COD) removal efficiencies. More than 99% phenol, 95% resorcinol and 96% catechol and 89% COD removal efficiency was obtained at optimum conditions of HRT = 1.25 d and fill time = 1.5 h. The heating value of the sludge was found to be 12 MJ/kg. The sludge can be combusted to recover its energy value.

Palm Jumeirah, Dubai: cone penetrometer testing data from the carbonate sand fill

Palm Jumeirah was the first of the iconic Palm Islands to be reclaimed from the sea off the Dubai coastline. Extensive cone penetrometer testing (CPT) of the hydraulic fill was undertaken, both pre- and post-vibro-compaction, in order to evaluate the effectiveness of the ground improvement. A study of these data, together with standard penetration test (SPT) and shear wave velocity results, is presented for this shelly carbonate sand fill. Large peaks in cone resistance qc were recorded at the start of penetration, which were not considered representative of the undisturbed fill. These were possibly caused by crushing of the friable shelly particles during cone penetration, leading to the formation of a high-density soil plug around the cone. Secondary compression or other ageing mechanism may have occurred at depth in the fill, as well as an apparent longer-term increase in cone resistance with time in the fill above and around groundwater level. However, at a nearby site, in the short term, an apparent decrease in cone resistance with time was observed at the same depth in a similar fill material. In addition, the effect of vibro-compaction point spacing on post-densification CPT results is presented, along with the effect of mean particle size on SPT–CPT correlation.

Flow Rate Computations in Hydraulic Fill Mine Stopes

Mining is a major industry worldwide, where hydraulic fills are commonly used for backfilling the underground voids created in the ore removal process. Hydraulic fills placed in the form of slurry drain through free draining barricades that block the access drives during the filling process. Failure of the barricades, followed by the in-rush of tailings into the mine can be catastrophic. This paper describes a simple method based on three-dimensional method of fragments, for computing the flow rates. Laboratory tests were carried out on model stopes filled with sands, and the measured flow rates compared well with those computed using the proposed method. This was also verified through numerical modelling. The proposed expressions for computing the flow rate in the three-dimensional hydraulic fill stope can be useful in the development of a spreadsheet-based fill simulation program that will help in monitoring the water level and flow rate within the stope, and improve mine safety.

Assessment of slurry consolidation using index properties

Several engineering applications involve dilute slurries such as mine tailings, municipal sludges, dredged materials, and hydraulic fills. An assessment of the consolidation behavior is pivotal for minimizing the environmental footprint of these fine-grained slurries at the outset of deposition. The volume compressibility and hydraulic conductivity properties during dewatering are governed by complex solid–liquid interactions that are captured by the index properties. This study focused on analyzing slurry consolidation in conjunction with soil consistency. Results indicated that the consistency limits for sedimentary clays covered a wide range due to the presence of various clay minerals. Sesquioxide coating of clays and dominance of non-clays resulted in lower liquid and plastic limits for residual soils. The relatively high limits for oil sand tailings were due to residual bitumen that imparts thixotropy and lubrication. The analyzed consolidation data (σ′ = 1 kPa to 450 kPa, e = 10 to 1, and k = 10−4 to 10−9 cm s−1) for each material group fitted best to a decreasing power law for compressibility and an increasing power law for conductivity. The 99% confidence intervals were wide at low σ′ and high e and gradually narrowed down with a change in these parameters. The volume compressibility coefficients (A and B) linearly varied with Ip whereas the hydraulic conductivity coefficients (C and D) followed decreasing power law functions of Ip. Strong agreements between measured and modeled data were obtained for both void ratio (R2 = 0·98) and hydraulic conductivity (R2 = 0·99).

Tailings Liquefaction Analysis Using Strength Ratios and SPT/CPT Results

Tailings dams constructed using the upstream method generally have relatively low- density materials with a high degree of saturation. Such conditions can generate the phenomena of liquefaction, which is potentially critical in slurry tailings disposal systems. Slope stability analyses involving liquefied soil require that the shear resistance of the softened soil be estimated and then, a good practical alternative is back-analyzed with field case studies involving slope failures, using commonly SPT and CPT results. The Olson (2001) and Olson &amp; Stark (2003b) liquefaction analysis methodology based on strength ratios, included in this approach, is comprised of three stages: (i) liquefaction susceptibility analysis; (ii) triggering analysis; and (iii) post-triggering - flow failure stability analysis. In this paper, this approach was applied for stability assessments to verify liquefaction potential in an upstream tailings dam built by the hydraulic fill technique and located in the Quadrilátero Ferrífero (Iron Quadrangle) region, southeastern of Brazil. The results ratified the safety condition of the impoundment although they have demonstrated that the tailings tend to exhibit contractile behavior during shear, indicating liquefaction susceptibility.

Liquefaction Testing of Stratified Sands Interlayered with Silt

The cyclic behavior of stratified sands interlayered with silt is at present poorly understood, although stratified sands exist for various soil deposits and hydraulic fill, which have a history of liquefaction during earthquakes. The main objective of this research project was to compare the cyclic behavior of stratified and homogeneous sands for various silt contents. A comprehensive experimental program was undertaken in which stain-controlled undrained cyclic triaxial tests for stratified sand samples interlayered with different thickness silt were performed. The silt thickness ranged from 0 to 80mm was considered. The confining pressure in all test series was 100kPa. The results indicate that the thickness of the silt seam sandwiched in the sand samples has a significant influence on the liquefaction resistances of layered sands. In other words, there is a critical thickness of silt seam that the saturated stratified sands have a critical shear strain. This finding justifies applying the laboratory tests results of homogeneously reconstituted samples to the field conditions for the range of variable studied.

The Prediction Model Study of the Hydraulic Fill Elevation in Reclamation Project

The determination of the hydraulic fill elevation is one of the urgent problems in reclamation project. The determination of the hydraulic fill elevation is of extreme importance to the final design elevation in reclamation project. If the hydraulic fill elevation is over high, might waste the hydraulic fill resources, and soil strength would decreased greatly when reduce the topsoil to reach design elevation. If the hydraulic fill elevation is over low, twice-fill is needed leading to great increased coast. In the paper, observational settlement prediction system of dredger fill had been established by research of BP artificial neural network. Finally, the hydraulic fill elevation of reclamation project was suggested reasonably by the observational settlement prediction system.

Rapid Improvement Technique of Shallow Base in Super-Soft Foundation

Dredged soil once was considered as the waste and abandoned, which had resulted in serious environment pollution and high costs. Since the viewpoint of “Utilize Dredged Soil Valuably” was proposed in 1980s, the dredged soil has been used as the hydraulic fills in land reclamation, which can meet the requirements of the booming land expansion. However, most of the fresh hydraulic soil is the floating or fluid mud, and has high water content but little bearing capacity, so it is difficult for the traditional treatment methods to improve the super-soft foundation. Based on the drainage and consolidation theory, the rapid improvement technique without sand cushion for the shallow base was developed and has been applied successfully in engineering practices. The applications showed that the rapid improvement technique improved the bearing capacity of super-soft foundation substantially, and compared with the traditional vacuum preloading method, this new technique is more environment-friendly and cost-saving.

Experimental and Physical Modeling of Bed Load Heterogeneous Sediment Transport

AbstractThe hydraulic deposition process linked to tailings dams normally presents some technical deficiencies mainly because of the lack of control of hydraulic parameters. Problems of instability in tailings dams usually arise from poor management practices, such as poor decant pond control, in addition to the material being placed randomly. Hydraulic parameters, such as the flow rate and concentration of the slurry, play an important role in the formation of hydraulic fills. Grain size, distribution, segregation, and density, and slope inclination are the main characteristics of tailings dams, which are affected by the hydraulic parameters of the slurry. To investigate these factors, an experimental apparatus [hydraulic deposition simulation test (HDST)] was used to simulate the hydraulic deposition process in the laboratory, where all variables that could affect the phenomenon could be controlled carefully. The HDSTs using different flow rates and concentrations were carried out using the iron waste f...