Stresses in soil–bentonite slurry trench cut-off walls

Li, Yuchao; Cleall, Peter John; Wen, Yi-Duo; Chen, Yunmin; Pan, Qian

doi:10.1680/jgeot.14.p.219

Cited by 31 publications

(28 citation statements)

References 13 publications

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“…For the SHMP-20CaB preparation, tap water-SHMP-CaB slurry composed of 20 wt% amended bentonite was prepared and used to increase moisture content of the backfill to satisfy the target slump height. The SHMP-CaB slurry had Marsh viscosity of 39 s, filtrate loss of 22.6 mL, density of 1.15 g/cm 3 , and pH of 6.8 after hydration for 24 h. To control bentonite content in the backfill to be constant 20 wt%, additional amount of sand was added with the slurry during the slump tests. Moisture content of the prepared 20CaB backfill and SHMP-20CaB backfill at the target slump was 29.6% and 30.0%, respectively.…”

Section: Hydraulic Conductivity Testsmentioning

confidence: 99%

“…The SB slurry walls may be used as an interim measure for the short-term containment of impacted groundwater until an efficient and effective treatment technology is developed and deployed [2]. Low permeability and the contaminant sorption capacity are the two dominated properties of the backfill that control the containment performance of the walls [3,4]. To enhance service life and/or service performance of the SB slurry walls, novel bentonites including multiswellable bentonite MSB, contaminant-resistant bentonite SW101 [5], and bentonite-polymer composite BPC [6] were developed to reduce hydraulic conductivity of the SB backfills.…”

Section: Introductionmentioning

confidence: 99%

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SHMP-Amended Ca-Bentonite/Sand Backfill Barrier for Containment of Lead Contamination in Groundwater

Yang

Reddy

Zhang

et al. 2020

IJERPH

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This study investigated the feasibility of using sodium hexametaphosphate (SHMP)- amended calcium (Ca) bentonite in backfills for slurry trench cutoff walls for the containment of lead (Pb) contamination in groundwater. Backfills composed of 80 wt% sand and 20 wt% either Ca-bentonite or SHMP-amended Ca-bentonite were tested for hydraulic conductivity and sorption properties by conducting laboratory flexible-wall hydraulic conductivity tests and batch isothermal sorption experiments, respectively. The results showed that the SHMP amendment causes a one order of magnitude decrease in hydraulic conductivity of the backfill using tap water (1.9 to 3.0 × 10−10 m/s). Testing using 1000 mg/L Pb solution resulted insignificant variation in hydraulic conductivity of the amended backfill. Moreover, SHMP-amendment induced favorable conditions for increased sorption capacity of the backfill, with 1.5 times higher retardation factor relative to the unamended backfill. The Pb transport modeling through an hypothetical 1-m-thick slurry wall composed of amended backfill revealed 12 to 24 times of longer breakthrough time for Pb migration as compared to results obtained for the same thickness slurry wall with unamended backfill, which is attributed to decrease in seepage velocity combined with increase in retardation factor of the backfill with SHMP amendment. Overall, SHMP is shown to be a promising Ca-bentontie modifier for use in backfill for slurry trench cutoff wall for effective containment of Pb-contaminated groundwater.

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Section: Hydraulic Conductivity Testsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

SHMP-Amended Ca-Bentonite/Sand Backfill Barrier for Containment of Lead Contamination in Groundwater

Yang

Reddy

Zhang

et al. 2020

IJERPH

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“…[9] Yet, new construction methods of underground walls in unstable soils were introduced in the 1940s in Italy and spread throughout the world. [10] The Slurry Trench Method of excavation [11,12] was first proposed in the United States more than 70 years ago, and consequently, a cutoff wall was constructed by Slurry Trench Method in 1948 in the Iceland Terminal of California. [13] The wall had a depth of 15 meters.…”

Section: Literature Reviewmentioning

confidence: 99%

Construction and Monitoring of Cement/Bentonite Cutoff Walls: Case Study of Karkheh Dam, Iran

Faridmehr

YazdaniPour²,

Jokar³

et al. 2019

Studia Geotechnica Et Mechanica

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Water seepage is one of the most important features of embankment dams. To prevent and reduce seepage, it is necessary to seal the dam. Plastic concrete cutoff walls are one of the most efficient methods in waterproofing the foundation of embankment dams on permeable alluvial substrates. Sufficient resistance to loads, low permeability to maintain dam sealing, high ductility compatible with the foundation and deformation under load without cracking are the main requirements in plastic concrete cutoff walls. In this paper, the construction and implementation of the cutoff wall of Karkheh Dam, which is one the world's largest water sealing projects, was studied. In addition, a numerical model using Seep-3D software was developed to evaluate the efficiency of the cut-off wall to decrease the seepage over the dam's foundation. The numerical results validated by instrumentation statistics resulted from 17-years dam operation. According to the results, after the drainage of the reservoir, the cutoff wall optimally reduced the hydraulic gradient by 0.08 from 2.35 and the water leakage by 3.1 m/s from 18.3 m/s.

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“…Consequently, an appropriate prediction of the lateral earth pressure development within the slurry wall is important. The hypothesis of the lateral squeezing modeling was initially proposed by Filz [5], and this method for modeling was then developed by many researchers considering the arching and squeezing effect for deep trenches [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

“…A two-dimensional CSB slurry wall, with width and depth of B and H, respectively, surrounded by submerged medium dense sand, is investigated in this paper. It is assumed that the mixture placed into the trench along with the surrounding soils is homogeneous and isotropic, and the groundwater table is at the surface [5][6][7][8]. Since the horizontal strain of mixtures after placement is expected to be zero, the geometry of the problem is identified as plain-strain.…”

Section: Introductionmentioning

confidence: 99%

Lateral squeezing effects on cement-slag-bentonite slurry wall performance

Talefirouz

Çokça

2021

Materials and Geoenvironment

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Cement-slag-bentonite slurry walls are self-hardening structures, and they are mainly used to retard contamination transport into the groundwater stream. Whilst permeability of a mixture is an initial criterion in slurry wall design and material selection, long-term performance is mainly influenced by curing ages and stress-state caused by adjacent soil. In this study, the steady-state of effective stresses at 7 days and 28 days of curing age is predicted. The effect of the modulus of horizontal subgrade reaction, interface friction, and transition of the earth pressure from at-rest to the active condition was applied to develop the model. Unlike the quantities that the geostatic model presented, this method gives a slight decrease of stresses after a certain depth, and the trend is in good agreement with trends provided by previous studies. Furthermore, the predicted stresses are then applied to estimate the permeability of the wall at each depth and compare it with those obtained in the laboratory. Finally, predicted effective stresses stay lower than geostatic stress, and the slurry wall consolidation along with the sidewalls’ lateral squeezing leads to keeping the stress state under control.

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Stresses in soil–bentonite slurry trench cut-off walls

Cited by 31 publications

References 13 publications

SHMP-Amended Ca-Bentonite/Sand Backfill Barrier for Containment of Lead Contamination in Groundwater

SHMP-Amended Ca-Bentonite/Sand Backfill Barrier for Containment of Lead Contamination in Groundwater

Construction and Monitoring of Cement/Bentonite Cutoff Walls: Case Study of Karkheh Dam, Iran

Lateral squeezing effects on cement-slag-bentonite slurry wall performance

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