Primary Consolidation Research Articles

Wrist arthrodesis with afixed-angle, "low-profile" fusion plate without carpometacarpal joint fixation

Total wrist arthrodesis to improve functional use of the hand by reducing pain and increasing grip strength. Painful destruction of the radio- and midcarpal joints. Analgesia and satisfactory hand function after motion-preserving surgical or conservative treatment. Chronic joint infection. Posterior approach to the wrist. Removal of articular surfaces destroyed all the way down to cancellous bone. Filling of defects with cancellous bone graft taken from distal radius or iliac crest. Osteosynthesis with fixed-angle wrist fusion plate without carpometacarpal (CMC) III joint fixation. Below-elbow cast for 2weeks. Immediate active motion fingers exercises. X‑ray control 6weeks postoperatively. Gradual increase of normal hand use in daily life after bony consolidation. Total wrist arthrodesis was performed using afixed-angle fusion plate without CMCIII joint fixation in 28patients (21men, 7women). Afollow-up of 14/28patients was performed at amean of 21 (3-39) months postoperatively. Grip strength improved from 14 (0-38) kg preoperatively to 22 (12-40) kg postoperatively. The average postoperative DASH score was 40 (6-72) points. Pain measured with the VAS scale (0-10) improved from an average of 7 (3-10) points preoperatively to 2 (0-6) points postoperatively. Overall, 13/14patientswere satisfied with the treatment; 26/28patients achieved primary bony consolidation. Postoperative complications found in 9 of 28patients: 2 nonunion, pain in the CMCII (n= 3) or III (n= 1) joints, 2 screw breakage, 1 postoperative bleeding and 1 infection. Both cases of nonunion healed after plate removal, re-osteosynthesis with astraight wrist arthrodesis plate, bridging the CMCIII joint, and abone graft from the iliac crest. All patients with CMCII joint pain were pain-free after removal of the protruding screw. One patient had chronic pain in the CMCIII joint despite plate removal. In the 2cases with screw breakage, no issues caused. In one patient, after primary bony consolidation, removal of the plate was performed for extensor tenolysis and not as aresult of the broken screw. In the second patient, removal of the plate after primary bony consolidation was unnecessary as the patient was pain-free in the area of the broken screw, yet aprotruding screw in the CMCII joint cavity was removed.

Effect of organic matter in soft soils on the effectiveness of preloading for foundations

This paper examines the effect of organic matter in soil on the effectiveness of preloading soft ground to accelerate primary consolidation and mitigate creep settlements prior to foundation construction. Four organic matter contents (1·2, 4·1, 6·4 and 8·3%) and two preloading levels (25 and 50 kPa) are studied. The increase in organic matter content has a significant impact on primary and secondary consolidation, inducing an increase in the void ratio, compressibility indices and creep deformations, and a decrease in the coefficient of consolidation. The results show that the creep strain with log time changes from a linear trend for samples without preloading to an increase in the creep strain rate for samples submitted to preloading. The results of the creep tests also highlight that preloading is more effective for a higher preloading level, in the short term, and for higher organic matter content.

Analysis and discussion on post-construction settlement of soft soil foundation treatment test section of highway

Combined with the settlement observation data in soft soil foundation test section of highway projects, the final settlement of soft soil foundation by preloading was calculated by using three-point method, Asaoka method and hyperbola method, and the comparative analysis on the final settlement and post-construction settlement of soft soil foundation were conducted by various calculation methods, then the suitability of calculation methods for post-construction settlement of highway soft soil foundation was discussed. And the results are shown as follows: (1) The final settlement results calculated by three-point method and Asaoka method were less than hyperbolic method, due to only considering the primary consolidation settlement for the first two methods; the calculation results of three methods were close to each other when the secondary consolidation settlement was considered, and the secondary consolidation settlement should be considered when the post-construction settlement was calculated by the first two methods. (2) The post-construction settlement and differential settlement of soft soil foundation test section of highway calculated by three methods were all satisfied with the design requirements.

INNOVATIVE IMPLICIT FINITE DIFFERENCE SOLUTION TO TIME RATE OF SETTLEMENT IN CLAY

The primary consolidation process in clay involves changes in excess pore water pressure (EPWP) with time. The changes in the EPWP are related to permeability, void ratio, and boundary conditions. Closed-form solutions for simple initial EPWP have been published. Such solutions include simplifying assumptions and limited to few impractical initial EPWP distributions. Generally, the initial EPWP encountered in practice is complex, in which case, numerical methods are used. The finite differences and the finite element methods are the primary tools employed in the analysis of settlement behavior of fine-grained soils. Unfortunately, these methods suffer from three main problems: (1) they require evaluation of EPWP vectors at each time increment which results in a large number of calculations; (2) roundoff errors at each time increment; and (3) the solution for a given initial EPWP distribution is achieved at a predetermined integer time increment. An innovative explicit finite difference model is proposed that will permit any initial EPWP distribution, substantially reduces the number of calculations and roundoff errors.

Analysis of load-settlement behaviour of shallow foundations in saturated clays based on CPT and DPT tests

]Static Penetration Test (CPT) and Dynamic Penetration Test (DPT) are commonly used in-situ tests in a routine geotechnical investigation. Besides their use for qualitative investigation (lithology, homogeneity and spatial variability), they are used as practical tools of geotechnical characterization (resistance to the penetration, soil rigidity) and modern foundation design as well. The paper aims at presenting the results of an extensive research work on the evaluation of the 1D primary consolidation settlement of saturated clayey soils on the basis of the CPT or DPT tests. The work is based on an analysis of the correlations between the tip resistance to penetration measured in these tests and the parameters of compressibility measured by the compressibility oedometer test, through a local geotechnical database in the northern Algeria. Such an analysis led to the proposal of two methods of calculation of the settlement, one based on the CPT test and the other one on the DPT. The comparison between the predicted settlements and those computed on the basis of the oedometer test showed a good agreement which demonstrate the possbility to use the CPT and DPT tests as reliable tools of computation of foundation settlements in clayey soils.

Long-term settlement behavior of soft grounds and secondary compression

Settlement–time behaviors in the last stage of consolidation are studied both in the laboratory and in the field. It is shown that the long-term settlement–time curves observed in the field are linear with the logarithm of time and the rate of the long-term settlement are analogous to the rate of secondary compression measured in a laboratory. The finite difference consolidation analyses for cohesive soils exhibiting large amounts of secondary compression during primary consolidation provide fairly good predictions of the settlement–time curves observed in the laboratory and in the field. In this paper, the applicability of the secondary compression model established in the laboratory is examined in in situ conditions. The initial rate of secondary compression used in this paper has a predominant influence on the settlement–time curve with different drainage distances. It is emphasized that the assumption for unknown secondary compression behaviors during the primary consolidation has a predominant influence on the settlement–time curve.

Role of chest x-ray in assessing severity of pneumonia in children aged 3 months to 59 months

Introduction: Pneumonia is the leading cause of death in children worldwide. Accurate assessment of severity and prognosis is important to decide management of pneumonia. The objective of present study is to study role of Chest X-ray in predicting severity of pneumonia in children. Material & Methods: A total of 307 children aged 3 months to 59 months diagnosed with Pneumonia & Severe pneumonia as per World Health Organization (WHO) criteria were included in study. Chest radiographs were reported by Pediatric Radiologist and findings classified as Normal, Primary End point consolidation, Other Infiltrates, Pleural effusion. Results were compared in sub-group i.e. Pneumonia & Severe Pneumonia. Result: Hypoxia, cyanosis, grunting and severe malnutrition were found to be poor predictors of radiographic pneumonia. Bilateral infiltrates (30%) & Primary end point consolidation on right side (17%) are independent determinant of severity of pneumonia. Bilateral consolidation and bilateral pleural effusion on chest X-ray are associated with poor outcome. Conclusion: Children with cyanosis, grunting, hypoxia & severe malnutrition should preferentially have chest Xray done since they are more likely to have consolidation, infiltrates or pleural effusion. Children with Bilateral infiltrates, Consolidation and Bilateral pleural effusion should preferably be admitted to pediatric intensive care unit for more aggressive monitoring and management, since they have poor outcome.

Physicochemical and consolidation properties of compacted lateritic soil treated with cement

The consolidation of a fine-grained lateritic soil, treated with compound Portland cement (CEMII/BM 32.5N) up to 9% by weight of the dry soil and prepared at three different molding water contents (ωDRY, OMC, and ωWET), was investigated by means of a one-dimensional consolidation test. The physicochemical and microstructural properties of the compacted lateritic soil-cement mixture were investigated using Raman spectroscopy, polarized light microscopy (PLM), scanning electron microscopy (SEM), and pH measurement. The results show that cement admixtures resulted in the formation of tobermorite, afwillite, ettringite, portlandite, and calcite. However, tobermorite and afwilite, which are calcium silicate hydrates (CSH) whose mechanisms of formation are the pozzolanic and alkali silica reactions, appear from 6% added cement. The fixing point of the pH (12.4) is also obtained from 6% added cement. It is the threshold value at which the material begins to develop an adequate mechanical performance. In general, as the content of cement in the soil is increased, the yield stress increases from 1 to 3 times in comparison to untreated soil. For effective vertical stresses smaller than the cement-induced yield stress, the primary consolidation process for specimens treated with cement is 2–7 times faster than that for specimens not treated with cement, while for effective vertical stresses higher than the cement-induced yield stress, the primary consolidation process for specimens treated with cement is about 0.5–1.5 times faster than that for specimens not treated with cement. Permeability and secondary compression are reduced 1–9 times and 2–11 times that of the untreated samples, respectively. These changes are attributed to the creation of chemical bonds and aggregation that accompany the addition of cement. The results also show that it would be desirable for soil samples to be prepared at the dry side of optimum (ωDRY) when the optimum moisture content (OMC) is not reached at the site. These results indicate that significant and desirable changes in soil behavior can be achieved when the soil is admixed with CEM II/BM 32.5N cement, thus providing the possibility of using the tested lateritic soil in road construction.

Non‐ionic soft materials influence on filtration resistance and cake dry matter content

Filtration of organic slurries is important in many industries but challenging because the hydraulic resistance is high due to gel materials in the slurries. Particles with solid polystyrene (PS) core and varying amount of poly(N‐isopropylacrylamide) (PNIPAM) gel surface were synthesized. At low amount of gel, the gel deformed and partly filled the cake void increasing the resistance. This was successfully fitted using a semi‐theoretical model for deformable particles. At high amount of gel, the gel deformed filling the entire cake void and the resistance was dominated by the gel. During consolidation, the primary retardation time increased three orders of magnitude with gel thickness as expected as primary consolidation were dominated by the dissipation of pore water. The secondary retardation time also increased but not as pronounced as primary retardation time. Secondary consolidation was due to local compression of the gel and therefore less dependent on gel thickness. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2241–2247, 2017

Secondary consolidation modelling by using rheological schemes

The paper presents the possibility of the secondary consolidation modelling in soil mechanics by using rheological schemes. Non-elastic rheological models represent time-dependent behaviour of the soil skeleton and should be expressed by appropriate constitutive relationships in the form of ordinary differential equations. On the other hand, the primary consolidation phenomenon caused by dissipation of the excess pore pressure is modelled by applying the well-known formulation proposed by Terzaghi and expressed by the partial differential equation. The resulting initial boundary value problem was solved numerically for three selected rheological schemes. Algorithms implemented in Mathematica were used for this purpose.

폐석회 매립지반의 지반공학적 특성 및 압밀침하량산정

이 연구의 목적은 소다회 생산과정에서 발생한 매립지의 압밀특성을 연구하는데 있다. 소다회를 생산하는 과정에서 발생하는 부산물의 주요성분은 대부분 석회석이다. 이 연구는 우선 폐석회의 압밀특성을 파악하기 위해 시추조사를 통한 불교란 시료를 채취하여 실내실험을 실시하였다. 실험결과 폐석회는 소성이 큰 유기질토로 분류되었으며, 유기물 함유량 시험결과 폐석회에 함유된 유기물 함량은 일반 점토에 비하여 높게 나타났다. 또한, 이론적인 방법과 압밀해석 프로그램에 의하여 폐석회의 압밀침하량과 이차침하량을 산정하였다. The purpose of this study is to examine the consolidation characteristics of waste landfill from sodium carbonate production. The waste lime is a byproduct from the production of soda ash. The consolidation settlement of waste lime landfill was determined for waste lime specimen which obtained from the field boring. The consolidation tests are conducted for determination of the primary and secondary consolidation settlements. The waste lime is classified as an organic soil with high plasticity. As a result of an organic content test, the contents of organic matter in waste lime is much higher than that of normal clay. Finally, the total consolidation settlement of waste lime landfill is calculated by using a theoretical method and computer program for the given initial void ratio, compression index, and embankment height.

Isotache model for consolidation with a small incremental load

To examine the applicability of an isotache model, two types of consolidation test were carried out: constant rate of strain (CRS) by changing the strain rate during the test, and an incremental loading (IL) test with small incremental ratios. It is found from the CRS tests that the stress shift caused by the strain rate change is nearly the same for all tested soils, but the behaviour after the change is different: some soils do not follow the isotache model. After selecting two typical soils (one follows the isotache model and the other does not), IL tests with various increment ratios and different durations at the loading stage prior to the incremental load were carried out to investigate how these parameters affect the strain–time relation. It is revealed that the strain–time relation is strongly governed by the magnitude of stress increments; in cases of small increments, most of the settlement is generated after the end of the primary consolidation. It is found that most test results can be interpreted by the isotache model. However, when the load duration at the loading stage prior to the incremental load is longer, the time–strain behaviour differs from that predicted by the isotache model.

IConsol.js: JavaScript Implicit Finite-Difference Code for Nonlinear Consolidation and Secondary Compression

AbstractIn this study, an implicit finite-difference code for nonlinear consolidation and secondary compression was developed and implemented in a publicly available JavaScript Web application. The rate of secondary compression was defined based on the distance in e-log10(σv′) space between a current point and a corresponding point on a reference secondary compression line (RSCL). Modeling secondary compression in this manner enables simultaneous occurrence of primary consolidation and secondary compression. The finite-difference code was first verified by comparison with three benchmarks. The influence of secondary compression on settlement versus time was then studied and found to be important for thick and/or low-permeability layers for which primary consolidation requires significant time. Overconsolidated soil was observed to result in an apparent increase in Cα with time, which was also observed in experimental data. Finally, secondary compression was found to be capable of generating excess pore pr...

Implementation of the Quebec mental health reform (2005-2015).

BackgroundThis study evaluates implementation of the Quebec Mental Health (MH) Reform (2005–2015) which aimed to improve accessibility, quality and continuity of care by developing primary care and optimizing integrated service networks. Implementation of MH primary care teams, clinical strategies for consolidating primary care, integration strategies to improve collaboration between primary care and specialized services, and facilitators and barriers related to these measures were examined.MethodsEleven Quebec MH service networks provided the study setting. Networks were identified in consultation with 20 key MH decision makers and selected based on variation in services offered, integration strategies, best practices, and geographic criteria. Data collection included: primary documents, structured questionnaires completed by 25 managers from MH primary care teams and 16 respondent-psychiatrists working in shared-care, and semi-structured interviews with 102 network stakeholders involved in the reform. The study employed a mixed method approach, triangulating the three data sources across networks.ResultsWhile implementation was not fully achieved in most networks, the Quebec reform succeeded in improving primary care services with the creation of adult primary care teams, and one-stop services which increased access to care, mainly for clients with common MH disorders. In terms of clinical strategies implemented, the functions provided by respondent-psychiatrists had a greater impact on the MH primary care teams than on general practitioners (GPs) in medical clinics; whereas the implementation of best practices were indirect outcomes of another reform developed simultaneously by the Quebec substance use disorders program. The main integration strategies used for increasing continuity of care and collaboration between primary care and specialized services were those involving fewer formal procedures such as referrals between teams and organizations. The lack of operational mechanisms and protocols governing new services and structures were important barriers to primary care consolidation and service integration, as was the lack of interest and involvement of most GPs in MH.ConclusionsSuccessful and sustained healthcare reform requires attention to process and outcomes as well as structural change or service reorganization. Six recommendations for more successful implementation of the Quebec MH Reform are provided, with implications for healthcare reform internationally.Electronic supplementary materialThe online version of this article (doi:10.1186/s12913-016-1832-5) contains supplementary material, which is available to authorized users.

Time and Strain-Rate Effects on Viscous Stress–Strain Behavior of Plasticine Material

AbstractA plasticine material exhibits the characterized viscous stress–strain behavior with some similarity to the behavior of clayey soils. This paper presents a series of experimental tests, which include oedometer tests, isotropic creep tests, and triaxial multistrain rate compression tests, on a plasticine material. The test study focuses on effects of time and strain rate on viscous stress–strain behavior of the plasticine material under one-dimensional (1D) straining, isotropic stressing, and triaxial compression conditions. Values of compression index (Cce), rebounding index (Cre), and creep coefficient (Cαe) are obtained from the 1D straining and 1D stressing test data. The plasticine material has no primary consolidation period, and creep occurs from the beginning. Values of Cce, Cre, and Cαe are smaller than those of the soft clays. The triaxial multistrain rate compression test data show that the stress–strain behavior of the plasticine depends on the strain rates and the confining pressures. ...

Application of Film-Like Sensors for K0and Pore Water Pressure Measurement in Clay During 1D Consolidation

In this study, the economical FlexiForce sensor, which is thin and flexible, was used to measure K0 and the excess pore water pressure during a 1D consolidation test on kaolinite clay samples. Before the sensor could be used in the measurement, a special waterproof coating was applied, after which sensor calibration was carried out. The coated FlexiForce sensor was incorporated into two types of tailor-made needle probes for the pore water pressure measurement. The experimental results demonstrate that the two types of needle probes can well capture the evolution of the induced excess pore water pressure during consolidation. Upon a loading increment, the measured excess pore water pressure at the middle of the sample continues to increase and reaches a maximum value at t = ∼4 min and subsequently start to decrease. There is a distinct change in the decreasing trend of the measured excess pore water pressure; the trend becomes mild after t = ∼480 min, indicating the end of primary consolidation. During secondary compression, the excess pore water pressure continues to decrease due to the continuous settlement. A constant K0 value, which is comparable to the prediction by Jaky's equation, is measured by the sensors in the loading path; during secondary compression, K0 increases with time.

Consolidation Coefficient by Combined Probabilistic and Least Residuals Methods

Abstract Accurate prediction of the rate of consolidation settlement is dependent upon a reliable method of determining the coefficient of consolidation (cv) and the time to end of primary consolidation of the natural soil. For this purpose, and to circumvent errors associated with graphical procedures in evaluating cv, a FORTRAN program was developed to determine the best fit of laboratory consolidation test data using a combination of a probabilistic method and a minimization of the sum of squared residual (SSR) method. The proposed computer procedure does not use any particular point on the time-settlement curve. The program uses ranges of probable values of d0, d100, and cv. For each set of values d0, d100, and cv selected in a random manner, the SSR is computed. The set of values with the smallest SSR is considered as the best fit. This procedure leads to suitable reference values of the coefficient of consolidation and the end of primary consolidation, and permits an assessment of the accuracy of classical graphical log(t) and t1/2 procedures.

Prediction of one-dimensional compression behavior of Nansha clay using fractional derivatives

ABSTRACTNansha clay is an interactive marine and terrestrial deposited soft clay that is widely spread in Guangzhou, Pearl River Delta, China. To avoid excessive settlement after construction, there is a need for better quantifying the time-dependent deformation of the soft clay. This paper presents a preliminary study to predict the one-dimensional compression of Nansha clay using fractional derivatives. A fractional Merchant model was introduced to describe the time-dependent settlement, and analytical solutions were obtained in terms of the Mittag-Leffler function. The oedometer test results were presented to validate this model. Compared with classical rheological models, the fractional derivative-based model enabled close estimation of the one-dimensional compression with fewer parameters. The meaning of the order of fractional derivative and its relationship with the clay physical properties were explored. It shows that a smaller value of this order corresponded to a higher coefficient of consolidation and a lower coefficient of secondary consolidation. The amplitude of both the primary and secondary consolidation of clay may be estimated quantitatively by the order of fractional derivative. Taken together, these results may open up new avenues for theoretical and empirical modeling of rheological phenomena in clay using fractional derivatives.

Centrifuge Testing of Model Levees atop Peat: Experimental Data

Four large-scale centrifuge tests were performed at the NEES@UCDavis equipment site to study the cyclic behavior of levee structures resting atop soft organic peat. The model configurations using a non-liquefiable levee focused on the seismic deformation potential of peat during primary consolidation and secondary compression. The tests performed with a sandy levee studied the liquefaction potential of saturated loose sand fill overlying soft peat as well as the levee-peat-interaction under different loading conditions. The models were subjected to scaled ground motions representative of the Sacramento/San Joaquin Delta. System instrumentation consisted of linear potentiometers, pore pressure sensors and accelerometers. Slow data recorded at 1 Hz document the settlements during spin up, application of ground motions, and spin down. Fast data sampled at 4,167 Hz measured the dynamic response of the system, the excess pore pressure increase and immediate settlements. The project is archived at the NEES data repository under nees.org/warehouse/project/1161 .

Nonlinear Finite-Strain Self-Weight Consolidation of Dredged Material with Radial Drainage Using Carrillo’s Formula

AbstractEstimation of the time-rate consolidation of dredged deposits is considerably complicated when vertical drains are installed to enhance the consolidation process of the soft-soil stratum, because the vertical drains are commonly installed before self-weight consolidation is complete. In this paper, two new methods are proposed to take into account both vertical and radial drainage conditions during the nonlinear finite-strain self-weight consolidation of dredged soil deposits (i.e., precise prediction of the self-weight consolidation behavior considering radial flow to the vertical drain). For one-dimensional nonlinear finite-strain consolidation in the vertical direction, the simplified Morris’s analytical solution and the primary consolidation, secondary compression, and desiccation of dredged fill (PSDDF) analysis are adopted. In addition, to consider the radial drainage, Barron’s vertical drain theory is used. The overall average degree of self-weight consolidation of the dredged soil is estim...