Model tests on single batter piles subjected to lateral soil movement

A series of laboratory tests have been carried out to investigate the lateral response of battered piles under lateral soil movement. Model tests were carried out using instrumented rigid aluminium piles. The piles were embedded in homogeneous sand soil at batter angles &beta = 0°, ±10° and ±20° were subjected to two types of lateral soil movement profile. The results obtained from the study are presented in terms of the bending moment, shear force, soil reaction, pile rotation and lateral deflections along the length of the batter pile. The results of model tests on single vertical and batter piles under horizontal loads showed that the batter angle (&beta) significantly influenced the response of the batter piles. Regardless of the value of sand density, bending moment and deflection with batter angles &beta = +10° or positive batter piles were higher compared then vertical piles and negative batter piles

Performance of axially loaded single pile embedded in cohesive soil with cavities

The stability of a single model pile located adjacent to a continuous cavity was studied. This paper is an attempt to understand the behaviour of axially loaded single pile embedded in clayey soil with the presences of cavities. The performance of piles located in such soils was studied analytically. A verification analysis was carried out on available studies to assess the ability of analytical model to correctly interpret the system behaviour. The study was adopted by finite element program (PLAXIS). The study included many cases; in each case, there is a critical value in which the presence of cavities has shown minimum effect on the pile performance. Figures including the load carrying capacity of pile with the affecting factors are presented. These figures provide beneficial information for pile design constructed close to underground cavities. It was concluded that the load carrying capacity of the pile is reduced by the presence of the cavity within the soil mass. This reduction varies according to the size and location of cavity

Numerical modelling of passively loaded pile groups

Piled foundations could be affected negatively as a result of passive loadings caused by nearby soil movement-induced activities, and failure of piles could happen in some sever cases. This paper deals with the numerical analysis of passively loaded pile groups and piled raft in sand. The complexity involved in such problems due to pile–soil, pile–pile, pile–cap, soil–cap, and moving soil-stable soil interaction needs a powerful tool to make three dimensional analysis possible. In the current study, PLAXIS 3D software was used to back analyse laboratory tests carried out by the authors. “Embedded pile” feature in which the pile is represented by beam elements, while soil-pile interaction along the pile shaft and at the pile tip is described by special interface elements was employed. The Mohr–Coulomb elastic–plastic constitutive model was used to describe the sand behaviour. Although an overestimation of the predicted deflection was obtained, the general trend of bending moment profiles of piles was in a reasonable agreement with those obtained experimentally. A number of limitations were identified as possible reasons behind the overestimation of the predicted deflections. Furthermore, parametric studies are adopted to consider the effects of pile diameter, pile–soil stiffness and pile group configuration on the response of passively loaded pile groups

Modelling the response of single passive piles subjected to lateral soil movement using PLAXIS

Response of single pile subjected to lateral displacements of soil mass using 3D finite element software (PLAXIS) is studied. Embedded pile feature in which the pile composed of beam elements with special interface elements to represent pile-soil interaction is used. The Mohr–Coulomb elastic–plastic constitutive model was employed for the soil stress-strain behaviour. A good agreement between laboratory and predicted results is observed in the validation analysis. A parametric study was conducted to investigate the influence of soil Young's modulus and soil movement profile on the response of single "passive pile". The software results revealed that the distribution of bending moment along the pile length vary considerably and was in a very good agreement with the real pile behaviour when adopting a variation of soil elastic modulus with depth instead of choosing a constant value

Model tests on piled raft subjected to lateral soil movement

Passive loadings due to lateral soil movement-induced activities are highly influencing the serviceability and safety of constructions. This research aims to investigate the influence of axial loads, sand density and the depth of moving soil on the lateral behaviour of piled raft under progressively moving sand. In order to achieve this goal taking into account the complex interaction effects of piles, cap and subsoil, a laboratory apparatus and small scale models have been designed and fabricated carefully to ensure a reasonable simulation of this geotechnical problem. It is found that the above parameters play an important role in the response of piled foundations. The value of soil displacement at which the measured moment reaches its ultimate value decreases as axial loads increase. Peak displacement of the raft has been found to be a function of soil density

Effect of cavities on the behaviour of model pile under axial loading in sand

Presence of cavities in soils is an important area of interest within the field of geotechnical engineering. A better understanding of the behaviour of such soils, particularly in locations where the presence of gypsum deposits is apparent, will have a large impact on the stability of foundations and allows designers and engineers to have a convincing explanation of this phenomenon on the stability of foundations in general. The research offers an experimental investigation to study the performance of axially loaded piles embedded in sandy soils with cavities. The experimental study comprised a full laboratory testing programme carried out on small scale piles embedded in predetermined cavities within a soil mass. The experimental model has the capability to investigate the effect of different cavity locations on the ultimate pile resistances. Thirteen cavity locations were chosen to study their influence on the ultimate carrying load of single pile. It was concluded that the maximum ultimate carrying load of the pile is reduced by the presence of the cavity within the soil mass. This reduction varies according to the cavity location. The effect of cavity’s presence on the ultimate bearing capacity of pile ranged from 0% to 30.82% for side cavities, while the range of reduction factor for cavities under the pile tip is from 31.58% to 43.4%. The reduction in pile capacity increases when the cavity is closer to the pile. Also, pile settlement value without cavity is less than the settlement of the same pile with cavity

Effects of axial loads and soil density on pile group subjected to triangular soil movement

Laboratory tests have been carried out to investigate the response of 2x2 pile group subjected to triangular soil movement. The pile group was instrumented with displacement and tilting devices at the pile cap and strain gauges on two piles of the group. In this paper, results from four model tests were presented to study the effects of axial loads and soil density on the lateral behavior of piles. The responses in terms of bending moment, shear force, soil pressure, deflection, and rotation of piles were compared. Test results indicate that increasing the soil strength could increase the measured moment, shear, soil pressure, and pile deformations. Most importantly, adding loads to the pile cap induces additional moment to the head of frontpile row unlike the back-pile row which was influenced insignificantly

Complicated Coeliac Disease : Diagnosis and Management

Dit proefschrift geeft een gedetailleerd overzicht van het management van gecompliceerde vormen van coeliakie, met name refractaire coeliakie, met de huidige onderverdeling in twee categorieën (RCD type I en II), en enteropathie geassocieerd T-cel lymfoom (EATL).Mulder, C.J.J. [Promotor

Open and / or laparoscopic surgical treatment of liver hydatic cysts

Hydatid disease is a severe parasitic disease with a widely ranging distribution. In the human being the liver is the most frequent organ affected. 1 The treatment should be individualized to the morphology, size, number and location of the cysts, that is why a variety of surgical operations have been advocated from complete resection like total pericystectomy or partial hepatectomy to laparoscopy to a minimally invasive procedures like percutaneous aspiration of cysts to conservative drug therapy. 3-4 This study compares laparoscopic versus open management of the hydatid cyst of liver the surgical approach to liver echinococcosis is still a controversial issue and shows our results of surgical treatment of liver hydatid cysts during a 3-years period

Prospective evaluation of the motorized spiral enteroscope for previous incomplete colonoscopy

Background and study aims  A significant percentage of colonoscopies remain incomplete because of failure to intubate the cecum. The motorized spiral enteroscope (MSE) technique, originally developed for deep small bowel enteroscopy, may be an effective alternative technique in cases of incomplete examination of abnormally long colons (dolichocolon). We prospectively evaluated the success rate of cecal intubation, safety and the therapeutic consequences of using MSE after incomplete conventional colonoscopy. Patients and methods  A total of 36 consecutive patients with an indication for diagnostic and/or therapeutic colonoscopy were prospectively enrolled in this multicenter trial. All patients had undergone at least one incomplete colonoscopy attributed to abnormally long colons. Patients with incomplete colonoscopy due to stenosis were excluded. Results  Twenty-two men and 14 women (median age 66 years, range 35–82) were enrolled. Median procedure time was 30 minutes (range 16–50). Cecal intubation rate was 100 % and median cecal intubation time was 10 minutes (range 4–30). Abnormalities, mostly neoplastic lesions, were detected in 23 of 36 patients, corresponding to a diagnostic yield of 64 %. All these findings were in the right side of the colon and had not been described by the antecedent incomplete coloscopy. No adverse events occurred. Conclusions  In case of a difficult and long colon, MSE is safe and effective for diagnostic and therapeutic colonoscopy. It may provide an attractive solution to accomplish completeness of previous incomplete colonoscopies in these patients