Controlling Conditions of the One-Dimensional Consolidation Test on Peat Soil

This paper studies the changes in the loss on ignition (LOI), total nitrogen content (TN), and strain in a one-dimensional consolidation test on peat soil. The effects of small-range fluctuations in the ambient temperature and changes in the sample height on the consolidation process of peat soil are proposed and verify the inhibitory effect of thymol on the decomposition of organic matter. The results show that when the ambient temperature fluctuates in a small range, the consolidation rate is significantly affected. Under a low load, the ambient temperature increases by 1–2 °C, and the consolidation rate can be increased by up to 10 times. This study presents the changes in loss on ignition (LOI) and total nitrogen content (TN) during consolidation, which proves that soaking the samples with a thymol solution can effectively control the decomposition of organic matter in peat soil. The strain of peat soil at a height of 30 mm is greater than or equal to that of other height samples, while that of mucky soil is 20 mm. Therefore, 30mm is the recommended sample height for peat soil for the one-dimensional consolidation test.

An approach for modelling spatial variability in permeability of cement-admixed soil

This paper presents a framework for modelling the random variation in permeability in cement-admixed soil based on the binder content variation and thereby relating the coefficient of permeability to the unconfined compressive strength of a cement-admixed clay. The strength–permeability relationship was subsequently implemented in random finite element method (RFEM). The effects of spatial variation in both strength and permeability of cement-admixed clays in RFEM is illustrated using two examples concerning one-dimensional consolidation. Parametric studies considering different coefficient of variation and scale of fluctuation configurations were performed. Results show that spatial variability of the cement-admixed clay considering variable permeability can significantly influence the overall consolidation rate, especially when the soil strength variability is high. However, the overall consolidation rates also depend largely on the prescribed scales of fluctuation; in cases where the variation is horizontally layered, stagnation in pore pressure dissipation may occur due to soft parts yielding.

Preliminary Characterization of Co-processed Excipients of Okra (Abelmoschus esculentus) Mucilage and Pregelatinized Potato Starch

Background: Okra mucilage is highly viscous with good binding properties in tablets. Pregelatinized starches have significantly improved flow properties but produce tablets of poor mechanical strength.Objective: Preliminary evaluation of co-processed excipients of Okra mucilage and pregelatinized potato starch as directly-compressible excipients.Methods: Polymers were characterized for morphology (SEM), crystallinity (FT-IR) and flow properties. Coprocessed excipients were developed with Okra mucilage and pregelatinized potato starch at different ratios of starch: mucilage (95:5, 90:10, 85:15, 80:20, 70:30), using the co-fusion method. The flow, packing and compaction properties of the co-processed excipients were evaluated using density measurements, angle of repose, angle of internal friction, Kawakita model, consolidation index (C) and consolidation rate (K).Results: Larger agglomerates of the co-processed excipients indicated formation of a new polymer. FT-IR spectra showed retention of all the major peaks of individual polymers. Okra mucilage imparted swelling while starch improved flow in the co-processed excipients (Hausner’s ratio 1.12-1.20). Values from Kawakita plots revealedcohesiveness and compressibility were imparted to the co-processed excipients (a = 0.300–0.329; b = 0.078–0.361) suggesting good compactibility. Consolidation index and rate were observed to increase with Okra mucilage content, implying improved rate of packing as well as enhanced flow (C = 0.566-1.389; K = 0.123-0.424). The batch containing starch: mucilage 70:30 gave the best properties of good flow, cohesiveness and compactibility, essential parameters required in directly-compressible excipients.Conclusion: The co-processed excipients of Okra mucilage and pregelatinized potato starch could therefore be used as excipients for direct compression in tablet formulations.

Field Test and Numerical Studies on Influences of PVD Spacing on Vacuum Treatment Effects of Dredged Slurry

A field test was conducted on vacuum treatment effects of a dredged slurry ground considering three PVD spacing, i.e., 700, 800, and 900 mm. The settlement and the pore water pressure dissipation were measured during the treatment period. As expected, the consolidation rate associated with closer PVD spacing case is higher than that of the larger spacing case. However, it is observed that the final and stable values of the settlement and the pore pressure dissipation of the close spacing case (e.g., 700 mm) are about 17% higher than the case of larger PVD spacing (e.g., 900 mm). The differences imply that enlarging the PVD spacing not only impedes the consolidation rate but also decreases the vacuum pressure in slurry. Numerical models incorporating the vacuum pressure attenuation effect and the clogging effect were established to reproduce the vacuum treatment process under the three PVD spacing. Good comparisons between the numerical and test results can be obtained given a proper account of vacuum attenuation and the clogging effect along the PVD depth. The comparison clarifies that, for vacuum treatment of slurry ground, the PVD spacing should be determined by due considerations both on the desired consolidation rate and on the pore water pressure that needs to be dissipated.

Differences between Two Methods to Stabilize Supramalleolar Osteotomies in Children—A Retrospective Case Series

Supramalleolar osteotomy (SMO) in pediatric patients can be fixed in various ways. We analyzed the records of 77 pediatric patients (124 SMOs) aged ≤16 years. In 56 patients (96 SMOs), K-wires were used to stabilize SMOs (WF group), while 21 patients (28 SMOs) were treated with locking compression plates (LCPs; PF group). We recorded time to radiographic consolidation, rate of complications, length of hospital stay (LOS), and time to implant removal. Mean time to radiographic consolidation of SMOs was 7.2 weeks in the WF group and 11.1 weeks in the PF group. Complication rate in the WF group was 10.7%. LOS was similar in the two groups (7.0 days in the WF group vs. 7.3 days in the PF group). K-wire stabilization resulted in a shortened interval until consolidation of osteotomies, but children were required to use a cast. Stabilization of SMOs with LCPs facilitated early mobilization and functional rehabilitation with no need to apply a cast. In conclusion, both methods provided safe fixation of SMOs with a low rate of complications. K-wire stabilization combined with a cast achieves fast consolidation of SMOs. We recommend SMO stabilization with angular stable LCPs in patients with muscular weakness or spasticity in whom early mobilization and physiotherapy are necessary to prevent loss of muscle power, muscle function, and bone mass.

Sleep-Related Declarative Memory Consolidation in Children and Adolescents with Developmental Dyslexia

Sleep has a crucial role in memory processes, and maturational changes in sleep electrophysiology are involved in cognitive development. Albeit both sleep and memory alterations have been observed in Developmental Dyslexia (DD), their relation in this population has been scarcely investigated, particularly concerning topographical aspects. The study aimed to compare sleep topography and associated sleep-related declarative memory consolidation in participants with DD and normal readers (NR). Eleven participants with DD and 18 NR (9–14 years old) underwent a whole-night polysomnography. They were administered a word pair task before and after sleep to assess for declarative memory consolidation. Memory performance and sleep features (macro and microstructural) were compared between the groups, and the intercorrelations between consolidation rate and sleep measures were assessed. DD showed a deeper worsening in memory after sleep compared to NR and reduced slow spindles in occipito-parietal and left fronto-central areas. Our results suggest specific alterations in local sleep EEG (i.e., sleep spindles) and in sleep-dependent memory consolidation processes in DD. We highlight the importance of a topographical approach, which might shed light on potential alteration in regional cortical oscillation dynamics in DD. The latter might represent a target for therapeutic interventions aimed at enhancing cognitive functioning in DD.

Outcomes of Surgical Management of Intraosseous Ganglia of the Carpal Bones: A Case Series

Background Intraosseous ganglia of the carpal bones are uncommon with sparse publications to guide treatment. The purpose of this study was to review a single-institution experience to determine the outcomes of patients with surgically treated intraosseous carpal ganglia. Methods Skeletally mature patients with intraosseous carpal ganglia between 1995 and 2016 treated operatively were identified. Demographic information, clinical data, and radiographic studies were evaluated. Results Thirty-three ganglia in 31 patients were identified. Intraosseous ganglia were located in the lunate (23), scaphoid (9), and trapezoid (1). Patients who presented with pathologic fracture or collapse had larger intraosseus ganglia than those presenting with pain alone. Surgery significantly improved pain. Patients treated with debridement with autograft bone graft had a higher consolidation rate compared with allograft bone but no difference in pain. Conclusions Patients with large or symptomatic lesions can be treated successfully with curettage and debridement, which leads to relief of pain. The use of bone grafting remains controversial.

Effect of a vacuum gradient on the consolidation of dredged slurry by vacuum preloading

In this paper, a large-scale indoor model test was carried out to reinforce the dredged slurry by vacuum preloading, and the effect of the vacuum gradient on the reinforcement effect was studied. The vacuum pressure, volume of extracted water, average ground settlement and pore water pressure were monitored during the test. After the test, the water content and vane shear strength were measured, and a particle analysis test and a scanning electron microscopy test were carried out. The results indicated that a small vacuum gradient could improve the consolidation degree and strength of the soil, and the smaller the vacuum gradient is, the better the reinforcement of the soil is. In addition, reducing the vacuum gradient could decrease the differential settlement of the soil surface and alleviate the migration of fine particles to the prefabricated drainage plates; therefore, the small vacuum gradient improved the clogging of the prefabricated drainage plates and the uniformity of soil consolidation. However, reducing the vacuum gradient also extended the test period, and a vacuum gradient of 20 kPa obtained the fastest consolidation rate of the soil.

Large-strain consolidation analysis of PVD-installed soft soil considering the discharge capacity variation according to depth and time

Purpose The consolidation behavior of prefabricated vertical drain (PVD)-installed soft deposits mainly depends on the PVD performance. The purpose of this study is to propose a numerical solution for the consolidation of PVD-installed soft soil using the large-strain theory, in which the reduction of discharge capacity of PVD according to depth and time is simultaneously considered. Design/methodology/approach The proposed solution also takes into account the general constitute relationship of soft soil. Subsequently, the proposed solution is applied to analyze and compare with the monitoring data of two cases, one is the experimental test and another is the test embankment in Saga airport. Findings The results show that the reduction of PVD discharge capacity according to depth and time increased the duration required to achieve a certain degree of consolidation. The consolidation rate is more sensitive to the reduction of PVD discharge capacity according to time than that according to the depth. The effects of the reduction of PVD discharge capacity according to depth are more evident when PVD discharge capacity decreases. The predicted results using the proposed numerical solution were validated well with the monitoring data for both cases in verification. Research limitations/implications In this study, the variation of PVD discharge capacity is only considered in one-dimensional consolidation. However, it is challenging to implement a general expression for discharge capacity variation according to time in the two-dimensional numerical solution (two-dimensional plane strain model). This is the motivation for further study. Practical implications A geotechnical engineer could use the proposed numerical solution to predict the consolidation behavior of the drainage-improved soft deposit considering the PVD discharge capacity variation. Originality/value The large-strain consolidation of PVD-installed soft deposits could be predicted well by using the proposed numerical solution considering the PVD discharge capacity variations according to depth and time.

The Secondary Consolidation (Creep) due to Geohistorical Overburden Pressure in the Houston-Galveston Region, Texas

The combination of groundwater withdrawal, hydrocarbon extraction, salt-dome movement and faulting have caused widespread subsidence in the Houston-Galveston region (HGR). Subsidence results from primary consolidation consisting of inelastic (nonrecoverable) and elastic (recoverable) compaction caused by subsurface fluid withdrawal and secondary consolidation (creep) over time caused by overburden pressure. Subsidence in the HGR is monitored using borehole extensometers that were installed at 13 locations across Harris and Galveston counties between 1962 and 1980. By 1977, withdrawals from the Chicot and Evangeline aquifers resulted in groundwater-level declines of about 114 and 115 m relative to predevelopment water levels, respectively in parts of Harris County. By 1979, as much as 3 m of land subsidence was estimated to have occurred in localized areas of the HGR. Land subsidence can be hazardous in populated areas because it exacerbates the effects of storm surge and impedes storm-water runoff by decreasing land-surface elevations in areas where water accumulates. To assess aquifer compaction in response to changes in groundwater levels, a bulk land-surface subsidence rate is assumed to be the sum of the primary consolidation rate and the negligibly variable component of overburden pressure referred to as the “pseudo-constant secondary consolidation rate.” From 1931 to 1976, groundwater levels decreased as groundwater withdrawal rates increased from 0.57 to 4.3 million m3 d−1, causing pressure heads in aquitards the Chicot and Evangeline aquifers to continually decline. In response to reductions in groundwater withdrawal rates from 4.3 to 3.0 million m3 d−1 between 1976 and 2001, groundwater levels rebounded, decreasing inelastic compaction rates in some parts of the HGR from as much as about 40 mm yr−1 in the early 1980s to negligible amounts by 2000. Inelastic consolidation from about 1937 to 2000 contributed to land-surface subsidence and its associated effects. Land-surfaces have rebounded in localized areas of the HGR where groundwater levels rebounded significantly. Pseudo-constant secondary consolidation rates were computed at each of the 13 extensometers and ranged from 0.48 to 8.49 mm yr−1 in areas where groundwater levels in the two aquifers were stabilizing. This secondary consolidation subsidence is beyond the control of any groundwater-level management schemes because it is caused by geohistorical overburden pressure on the two aquifers.