Modelling smear effect of vertical drains using a diameter reduction method

Vertical drains are used to accelerate consolidation of clays in ground improvement projects.Smear zones exist around these drains,where permeability is reduced due to soil disturbance caused by the installation process.Hansbo solution is widely used in practice to consider the effects of drain discharge capacity and smear on the consolidation process.In this study,a computationally efficient diameter reduction method(DRM)obtained from the Hansbo solution is proposed to consider the smear effect without the need to model the smear zone physically.Validated by analytical and numerical results,a diameter reduction factor is analytically derived to reduce the diameter of the drain,while achieving similar solutions of pore pressure dissipation profile as the classical full model of the smear zone and drain.With the DRM,the excess pore pressure u obtained from the reduced drain in the original un-disturbed soil zone is accurate enough for practical applications in numerical models.Such performance of DRM is independent of soil material property.Results also show equally accurate performance of DRM under conditions of multi-layered soils and coupled radial-vertical groundwater flow.

Palliative long-term abdominal drains vs large volume paracenteses for the management of refractory ascites in end-stage liver disease

BACKGROUND Long-term abdominal drains(LTAD)are a cost-effective palliative measure to manage malignant ascites in the community,but their use in patients with end-stage chronic liver disease and refractory ascites is not routine practice.The safety and cost-effectiveness of LTAD are currently being studied in this setting,with preliminary positive results.We hypothesised that palliative LTAD are as effective and safe as repeat palliative large volume paracentesis(LVP)in patients with cirrhosis and refractory ascites and may offer advantages in patients’quality of life.AIM To compare the effectiveness and safety of palliative LTAD and LVP in refractory ascites secondary to end-stage chronic liver disease.METHODS A retrospective,observational cohort study comparing the effectiveness and safety outcomes of palliative LTAD and regular palliative LVP as a treatment for refractory ascites in consecutive patients with end-stage chronic liver disease followed-up at our United Kingdom tertiary centre between 2018 and 2022 was conducted.Fisher’s exact tests and the Mann-Whitney U test were used to compare qualitative and quantitative variables,respectively.Kaplan-Meier survival estimates were generated to stratify time-related outcomes according to the type of drain.RESULTS Thirty patients had a total of 35 indwelling abdominal drains and nineteen patients underwent regular LVP.The baseline characteristics were similar between the groups.Prophylactic antibiotics were more frequently prescribed in patients with LTAD(P=0.012),while the incidence of peritonitis did not differ between the two groups(P=0.46).The incidence of acute kidney injury(P=0.014)and ascites/drain-related hospital admissions(P=0.004)were significantly higher in the LVP group.The overall survival was similar in the two groups(log-rank P=0.26),but the endpoint-free survival was significantly shorter in the LVP group(P=0.003,P<0.001,P=0.018 for first ascites/drain-related admission,acute kidney injury and drain-related complications,respectively).CONCLUSION The use of LTAD in the management of refractory ascites in palliated end-stage liver disease is effective,safe,and may reduce hospital admissions and utilisation of healthcare resources compared to LVP.

Recent evidence for subcutaneous drains to prevent surgical site infections after abdominal surgery:A systematic review and metaanalysis

BACKGROUND Surgical site infections(SSIs)increase mortality,hospital stays,additional medical treatment,and medical costs.Subcutaneous drains prevent SSIs in gynecological and breast surgeries;however,their clinical impact in abdominal surgery remains unclear.AIM To investigate whether subcutaneous drains were beneficial in abdominal surgery using a systematic review and meta-analysis.METHODS The database search used PubMed,MEDLINE,and the Cochrane Library.The following inclusion criteria were set for the systematic review:(1)Randomized controlled trial studies comparing SSIs after abdominal surgery with or without subcutaneous drains;and(2)Studies that described clinical outcomes,such as SSIs,seroma formation,the length of hospital stays,and mortality.RESULTS Eight studies were included in this meta-analysis.The rate of total SSIs was significantly lower in the drained group(54/771,7.0%)than in the control group(89/759,11.7%),particularly in gastrointestinal surgery.Furthermore,the rate of superficial SSIs was slightly lower in the drained group(31/517,6.0%)than in the control group(49/521,9.4%).No significant differences were observed in seroma formation between the groups.Hospital stays were shorter in the drained group than in the control group.CONCLUSION Subcutaneous drains after abdominal surgery prevented SSIs and reduced hospital stays but did not significantly affect seroma formation.The timing of drain removal needs to be reconsidered in future studies.

A new concept of backfll design—Application of wick drains in backflled stopes

Backflling represents an environmentally friendly mining waste disposal technique.It is increasingly used in underground mines all over the world.However,its primary purpose remains to improve ground stability and to reduce ore dilution.Previous investigations have shown that fll drainage plays a key role in backfll and barricade design.With a poor drainage system in the backflled stope,the required dimension of barricade,which is constructed at the base of the stope near the drift entrance,has to be increased.A poor backfll drainage system can also lead to a signifcant increase in drainage waiting time and further reduction in mining productivity.In this paper,the drainage of conventional backfll design in backflled stopes is briefly reviewed.For the frst time,the application of the wick drain is introduced in the backfll within mine stopes.The drainage improvement from the introduction of the wick drain is illustrated using numerical modeling.

Efficacy of subcutaneous penrose drains for surgical site infections in colorectal surgery

AIM: To investigate whether a subcutaneous penrose drain would decrease the superficial surgical site infection (s-SSI) rate in elective colorectal surgery. METHODS: This is a comparative study of the historical control type. Intervention consisted of the use of penrose drain in elective open colorectal surgical wounds. The outcome was an incidence of s-SSI. The patients were risk stratified according to the depth of subcutaneous tissue.RESULTS: There were 131 patients (40 patients with high s-SSI risk) in the prior period (from July 2008 to June 2009, when no penrose drains were inserted) and 151 patients (75 patients with high s-SSI risk) in the latter period (from June 2010 to November 2011, when penrose drains were inserted). The overall s-SSI rate was 6.1% and 5.3% during the two periods (P = 0.770), and the s-SSI rate in the high s-SSI risk group was 15.0% and 8.0% (P = 0.242).CONCLUSION: Although penrose drain was not observed to significantly reduce s-SSI, there tended to be a reduced risk of s-SSI in the high s-SSI risk group.

Robust design of self-starting drains using Random Forest

Groundwater lowering is one of the most important countermeasures to avoid the risk of rainfall-triggered landslides.However,the long-term reliability of many drainage methods is often a matter of concern since the drains may easily get clogged.A new hydraulic-driven self-starting drainage method is presented in this paper.In the proposed Random Forest(RF)based robust design approach for the selfstarting drains,the datasets are generated using an automatically controlled numerical modeling technology.The deterministic analysis is carried out based on uncertain soil parameters and the specific designs selected using Uniform Design(UD).The ensemble of RF models is applied in the design process to improve computing efficiency.Safety requirements,design robustness,and cost efficiency are simultaneously considered utilizing multiobjective optimization.A straightforward and efficient framework that focuses on difficulties caused by an enormous design space is established for the robust design of the self-starting drains,and improved computation efficiency is achieved.The effectiveness of the proposed approach is illustrated with a case study,the Qili landslide in Zhejiang Province,China.

A Model Study on Accelerated Consolidation of Coir Reinforced Lateritic Lithomarge Soil Blends with Vertical Sand Drains for Pavement Foundations

Sub-grade soils of lateritic origin encountered in the construction of highway embankments in various regions of India, often comprise intrusions of soft lithomargic soils that result in large settlements during constructions, and differential settlements at later stages. This necessitates the use of appropriate soil improvement techniques to improve the load-carrying capacity of pavements. This work deals with accelerated consolidation of un-reinforced and coir-rein- forced lateritic lithomargic soil blends, provided with three vertical sand drains. The load-settlement characteristics were studied for various preloads ranging from 50 kg (0.0013 N/mm2) to 500 kg (0.013N/mm2) on soil specimens prepared in circular ferro-cement moulds. It was observed that at lower preloads up to 200kg, across the blends, the relative increase in consolidation (Rct) for randomly reinforced soil with vertical drains was sig-nificantly higher than that of un-reinforced soil without vertical drains, with an average value of 124.8%. Also, the Rct for un-reinforced soil with vertical drains was quite higher than that of un-reinforced soil without vertical drains, with an average value of 103.9%. In the case of higher preloads, the Rct values for randomly reinforced soil with vertical drains were moderate with an average value of 30.88%, while the same for un-reinforced soil with vertical drains was about 20.4%. The aspect-ratio of coir fibers used was 1:275.

Drainage Management Problems Evaluation: Case Study Baloza and EL-Farama Drains, North Sinai, Egypt

Drainage management activities aim at maintaining the performance of drainage networks by assessing the major drainage management problems regarding sedimentation, bank erosion, vegetation, water quality, and biodiversity, to find appropriate solutions for channel improvement in order to increase agricultural productivity and maintain agricultural land and the surrounding environment. In this research, we evaluate the drainage management problems to the surface drains Baloza and EL-Farama in the cultivated Tina Plain region (21,000 hectares) North Sinai, Egypt to provide an accurate data to help decision-makers to know the status of maintenance of the watercourses and the need for improvement. For this, Intensive field investigations were carried out regarding a hydrographic survey of the actual drains cross-section using total station and aqua sounder devices, visual stream bank erosion survey, and vegetation survey. In addition, monthly water samples from the drainage water were treated and analyzed for physical and chemical, bacteriological related indices. The results showed, the studied drains suffer from sedimentation, vegetation infection, and bank erosion in some reaches and need remedy. Estimated sedimentation in EL-Farama Drain was 34369 m3/year and in Baloza Drain 29153 m3/year;bank slope failures upstream and downstream pump stations were recorded;the average weed infection ratio for both drains was 30%. The results of water quality parameters showed acceptable concentrations for BOD, DO, NO3, and total coliform according to Egypt decree, 92/2013 for the protection of the Nile River and its waterways from pollution, except TDS (more than 10,000 mg/L). The drainage water was classified as high saline and it was unacceptable for irrigation. Therefore, the author recommends to remove sedimentation and vegetation every 2 years by mechanical methods, applying gabions lining to prevent bank erosion, and treating drainage water using wetland system and utilizing the treated wastewater in fish farming.

Validations of new cut-offs for surgical drains management and use of computerized tomography scan after pancreatoduodenectomy:The DALCUT trial

BACKGROUND Postoperative pancreatic fistula(POPF)is the most fearful complication after pancreatic surgery and can lead to severe postoperative complications such as surgical site infections,sepsis and bleeding.A previous study which identified cut-offs of drains amylase levels(DALs)determined on postoperative day(POD)1 and POD3,was able to significantly predict POPF,abdominal collections and biliary fistulas,when related to specific findings detected at the abdominal computerized tomography(CT)scan routinely performed on POD3.AIM To validate the cut-offs of DALs in POD1 and POD3,established during the previous study,to assess the risk of clinically relevant POPF and confirm the usefulness of abdominal CT scan on POD3 in patients at increased risk of abdominal collection.METHODS The DALCUT trial is an interventional prospective study.All patients who will undergo pancreatoduodenectomy(PD)for periampullary neoplasms will be considered eligible.All patients will receive clinical staging and,if eligible for surgery,will undergo routine preoperative evaluation.After the PD,daily DALs will be evaluated from POD1.Drains removal and possible requirement of abdominal CT scans in POD3 will be managed on the basis of the outcome of DALs in the first three postoperative days.RESULTS This prospective study could validate the role of DALs in the management of surgical drains and in assessing the risk or relevant complications after PD.Drains could be removed in POD3 in case of POD1 DALs<666 U/L and POD3 DALs<207 U/L.In case of POD3 DALs≥252,abdominal CT scan will be performed in POD3 to identify abdominal collections≥5 cm.In this latter category of patients,drains could be maintained beyond POD3.CONCLUSION The results of this trial will contribute to a better knowledge of POPF and management of surgical drains.

Assessment of Wastewater Quality of Drains for Irrigation

Rapid industrialization and overpopulation have stimulated increase in waste water both domestic and industrial. Due to lack of inefficient sewerage system and absence of treatment plants, the wastewater is discharged into drainage systems causing environmental and health implications. At various points, the wastewater of these drains is used for irrigation purposes. This study characterizes the effluent of major drains of Lahore city and assesses its suitability for irrigation. Wastewater samples were collected from drains in winter and spring seasons and analyzed for various parameters of special concern to irrigation. TSS, oil and grease, BOD, COD, chloride, TDS, sodium, SAR, bicarbonate ions, EC, iron, Copper and Nickel were found to be varied in concentration in different drains when compared with NEQS (National Environment Quality Standards) and FAO guidelines for irrigation in both seasons. Regular monitoring and proper treatment of wastewater before discharging into the drains can reduce the pollution in these drains.

Loop Ileostomy and Colostomy—A Comparison between Supporting Plastic Rods and Epicutaneous or Subcutaneous Silicon Drains

Purpose: Beside the conventional plastic rods, different techniques and materials have been proposed in the last years to prevent the loop from retraction into the abdominal cavity. The aim of this retrospective comparative study was to assess three different techniques of loop support. Methods: The study included 65 pa- tients who had loop ileostomy or colostomy formed. Depending on the decision of the operating surgeon, one of three techniques was chosen to fixate the stoma loop: an epicutaneous plastic rod (group 1, n = 14), an epicutaneous suture-fixated silicone drain (group 2, n = 27), or a subcutaneous silicone drain (group 3, n = 24). Results: The majority of patients (85%) received loop ileostomy. Pain intensity was significantly (p = 0.0014) different among the three groups. A total of 19 patients (30%) suffered a complication. There was a tendency towards less complications if the stoma was secured by a silicone drain with epicutaneous fixation. Comfort with stoma care was significantly different, with group 3 experiencing the best results. Conclusions: Using a subcutaneously tunnelled silicon drain as a stoma bridge results in less complications, less pain and higher satisfaction as compared to the conventional plastic rod. Conventional plastic rods should be avoided.

Intraperitoneal drains during open appendicectomy for gangrenous and perforated appendicitis

Intra-abdominal drains are still routinely used in the surgical management of gangrenous and perforated appendicitis. A systematic review was performed with the aim of establishing their influence on postoperative complications in such cases. A literature search was conducted using the search engines Pub Med and Cochrance Central Register of Controlled Trials. Included were retrospective case-controlled and prospective randomized controlled trials on the use of drain for open appendicectomy in gangrenous and perforated appendicitis. Twelve articles were found that met the inclusion criteria. Intrabdominal abscesses, postoperative ileus, surgical site infections, fecal fistulas and burst abdomen had significant higher incidences in the drain vs non drain group(10.3%, 20.3%, 32.5%, 3.4% and 5.7% vs 4.7%, 8.5%, 16.2%, 0% and 0%, respectively). In most cases the risk was more than doubled in the drain group compared to the non-drain one. There were no significant differences among groups in termsof mortality while the results were underpowered to effectively evaluate wound dehiscence and adhesions. The use of intra-abdominal drains in the management of gangrenous and perforated appendicitis by open appendicectomy is associated with an increased rate of common postoperative complications.

Role of equal-strain assumption in unit-cell theory for consolidation with vertical drains

In the development of unit-cell theory for the analytical analysis of consolidation with vertical drains, the equal-strain assumption is often made with the intention of modelling consolidation under uniform settlement conditions. In contrast, the free-strain assumption for modelling consolidation under uniform load conditions is seldom employed, mainly because of the complexities involved in the analysis. This study derives a rigorous analytical solution to the generalised governing equations of free-strain consolidation with a vertical drain subjected to an instantaneous load. Calculated results from the newly proposed solution are compared with those from three available solutions derived based on the equal-strain assumption. Surprisingly good agreement is obtained in terms of excess pore-water pressure, degree of consolidation, and settlement. Horizontal profiles of settlement were not uniform before the end of consolidation. This indicates that the uniform settlement condition is not actually reproduced by the analytical solutions derived based on the equal-strain assumption. The equal-strain assumption is a sufficient but not necessary condition for deriving an analytical solution to unit-cell consolidation theory. The assumption plays no role in modelling consolidation under uniform settlement conditions but simplifies the analytical analysis of free-strain consolidation and results in an approximate solution of high accuracy for consolidation under uniform load conditions. Moreover, drain resistance and smear effects not only retard the consolidation rate, but also importantly shape the vertical and horizontal profiles of excess pore-water pressure, respectively.

Postoperative Drains at the Donor Sites of Iliac-Crest Bone Grafts in Patients Who Had a Single Comminuted Long Bone Fracture

In this clinical trial, 90 patients admitted to orthopedics ward, Shahid Mohammadi Hospital, Bandar Abbass with a long bone fracture, comminuted more than 30%, were randomly divided into two groups. In the first group, after the completion of the operation, a single hemovaccum drain was inserted into the iliac crest wound, the site of cancellous bone removal, whereas the second group didn’t receive a drain. The two groups were followed for at least six months and the results were compared with Chi-Square and T-Tests. The two groups, at the end of the follow up period, had no statistically significant difference with regard to pain severity and need for dressing change (in the immediate postoperative period), hematoma formation and infection. So it seems that drain insertion in the wound of patients in whom cancellous bone is removed from the iliac crest, is not necessary.

Simulating the Effect of Improving Water Quality at the El-Rahawy and the Tala Drains in the Rosetta Branch Water Quality

The El-Rahawy and the Tala drains are the major sources of pollution along the Rosetta branch. The El-Rahawy drain receives primary treated wastewater from the Abu-Rawash Wastewater Treatment Plant (WWTP), while the Tala drain receives discharge from dairy industry and agricultural drainage, as well as domestic wastewater. This research involved attempting to study the effect of improving water quality on the El-Rahawy and the Tala drains in the Rosetta branch water quality. Water quality at the El-Rahawy drain is expected to improve after discharging water from the Al-Buhairi Water Canal to the El-Rahawy drain and improving effluent water quality at the Abu-Rawash WWTP. Water quality at the Tala drain is expected to improve after constructing a new WWTP and improving effluent water quality at the dairy industry. The river pollutant (RP) modeling enabled studying the effect of improving water quality at the drains on the Rosetta branch water quality. The RP modeling showed that applying the proposed solutions would significantly improve water quality at the Rosetta branch.

Evaluation of Potential for Translocation of <i>Listeria monocytogenes</i>from Floor Drains to Food Contact Surfaces in the Surrounding Environment Using <i>Listeria innocua</i>as a Surrogate

Floor drains in processing environments harbor Listeria spp. due to continuous presence of humidity and organic substrates. Cleaning and washing activities in food-processing facilities can translocate the bacterial cells from the drain to the surrounding environment, thus contaminating food products still in production. This study evaluated the potential for translocation of Listeria monocytogenes from drains to food contact surfaces in the surrounding environment using Listeria innocua as a surrogate. A 7 × 7 × 8-foot polycarbonate flexi-glass chamber with a 10-inch-diameter drain mounted on an aluminum cabinet was used. Stainless steel coupons (6.4 × 1.9 × 0.1 cm, 12 per height) were hung at 1, 3, and 5 feet inside the chamber. Four treatment sets;non-inoculated, non-treated;non-inoculated, treated;inoculated, treated;inoculated non-treated;and two subtreatments of 8 h and 48 h were performed. For the inoculated sets, meat slurry (10 gof ground beef in 900 mL water) and a four-strain cocktail of Listeria innocua at 7 - 8 log CFU/mL were used. For the treated sets, in addition, a commercial cleaner and sanitizer was applied. The drain was cleaned using a pressure hose (40 - 50 psi) after 8 h and 48 h. Coupons were then removed and enriched in listeria enrichment broth to establish if any cell translocated from the drain onto the stainless steel coupons via aerosols generated during washing. Confirmation was done using VIP Listeria rapid test kits. Results indicated translocation at all three heights ranging from 2% - 25%. Significantly higher translocation (p Listeria spp. from drains to food contact surfaces does occur and increases with increased proximity to the drain.

Biological Control of Erosion of Banana Drains in Côte D’ivoire

The erosion of drains is a major limitation of the quality, the increasing of banana production and the environmental protection of industrial banana in C&#244;te d'Ivoire. It leads inundations, death of banana trees and significant loss of production. Thence, the construction and the maintenance of drain costs too much and causes injure, snake bite, physical traumatisms, many diseases, … These events compromise the sustainable production of banana by reducing seriously worker’s the activities and finally increase the cost of production. The aim of the present work is to contribute to the sustainable development and human capacity building in the third world nations as far as banana production is concerned. The methods used so far to address this phenomenon proved inefficient. The technology innovation in this area has been to grow grass on the outer edges of the channels drained water. This resulted in a systematic reduction of erosion. Better still, it helped fertilize the soil, reduce the deportations of fertilizer and improve the quality of landscape of the plantations. Stenotaphrum secondatum is the best vegetable specie adapted to the biological control against water erosion of drains.

Performance assessment of prefabricated vertical drains in mitigating soil reliquefaction subjected to repeated seismic events using shaking table experiments

The use of prefabricated vertical drains(PVD)in liquefiable deposits is gaining attention due to enhanced drainage.However,investigations on PVD in mitigating re-liquefaction during repeated shaking events are not available.This study performed a series of shaking table experiments on untreated and PVD-treated specimens prepared with 40%and 60%relative density.Repeated sinusoidal loading was applied with an incremental peak acceleration of 0.1g,0.2g,0.3g,and 0.4g,at 5 Hz shaking frequency with 40 s duration.The performance of treated ground was evaluated based on the generation and dissipation of excess pore water pressure(EPWP),induced sand densification,subsidence,and cyclic stress ratio.In addition,the strain accumulated in fresh and exhumed PVD was investigated using geotextile tensile testing apparatus aided with digital image correlation.No evidence of pore pressure was reported up to 0.2g peak acceleration for 40%and 60%relative density specimens.The continuous occurrence of soil densification and drainage medium restrained and delayed the generation of EPWP and expedited the dissipation process.This study demonstrates PVD can mitigate re-liquefaction,without suffering from deterioration,when subjected to medium to high intense repeated shaking events.

Semi-analytical solution for drained expansion analysis of a hollow cylinder of critical state soils

The expansion of a thick-walled hollow cylinder in soil is of non-self-similar nature that the stress/deformation paths are not the same for different soil material points.As a result,this problem cannot be solved by the common self-similar-based similarity techniques.This paper proposes a novel,exact solution for rigorous drained expansion analysis of a hollow cylinder of critical state soils.Considering stress-dependent elastic moduli of soils,new analytical stress and displacement solutions for the nonself-similar problem are developed taking the small strain assumption in the elastic zone.In the plastic zone,the cavity expansion response is formulated into a set of first-order partial differential equations(PDEs)with the combination use of Eulerian and Lagrangian descriptions,and a novel solution algorithm is developed to efficiently solve this complex boundary value problem.The solution is presented in a general form and thus can be useful for a wide range of soils.With the new solution,the non-self-similar nature induced by the finite outer boundary is clearly demonstrated and highlighted,which is found to be greatly different to the behaviour of cavity expansion in infinite soil mass.The present solution may serve as a benchmark for verifying the performance of advanced numerical techniques with critical state soil models and be used to capture the finite boundary effect for pressuremeter tests in small-sized calibration chambers.

A study of correlation between prosthetic breast reconstruction, antibiotic prophylaxis and surgical wound drains

Aim:The primary aim of this investigation into the correlation between prosthetic breast reconstruction,antibiotic prophylaxis and surgical drains was to determine whether the short-term prophylaxis recommended in the current guidelines is in fact able to sterilize the peri-prosthetic pocket in patients undergoing prosthetic breast reconstruction via tissue expansion,permanent implant placement,or Becker implants,as well as augmentation to correct symmetry.Methods:A total of 96 women who had undergone prosthetic breast reconstruction surgery were considered.Patients were recruited from the Plastic Surgery Clinic,Gemona,and the Surgery Clinic,Udine,both affiliated with the Udine'Santa Maria della Misericordia'University Hospital between May 2013 and May 2014.All patients were administered the recommended short-term antibiotic prophylaxis,i.e.2 g cephazolin(plus 1 g eventually given after 3.5 h of surgery)30 min before surgery.Records pertaining to each patient were kept in a specific study chart.Results:Samples of peri-prosthetic drainage fluid were taken from 92.5%of the recipients of breast reconstruction/implant surgery.Only 2.3%of the samples analyzed were found to be positive for microbial strains.Conclusion:The results of this preliminary study are encouraging,demonstrating that the guidelines regarding short-term antibiotic prophylaxis are indeed effective.