ICE - Institution of Civil Engineers - Virtual Library

Boltby reservoir, North Yorkshire, UK, was completed in 1880 as a means of water supply to the local area. In June 2005 a flood event with a return period in excess of 1 in 10 000 years caused significant damage to the masonry-lined spillway structure. The reservoir had not been used for supply since 2003 and it was subsequently decided to discontinue the reservoir under section 13 of the Reservoirs Act 1975. The discontinuance work consisted of the excavation of a notch in the dam approximately 70 m wide at crest level. A new low-level overflow channel was constructed at the bottom of the notch such that the remaining dam impounds less than 25 000m³ of water. Construction work began in early October 2006 and the discontinuance phase of the scheme was completed in late February 2007. This paper describes the design and construction phase of the discontinuance project including the development of a detailed water level control and contingency plan and a large amount of environmental engineering works.

Strines reservoir in South Yorkshire is constructed across a tributary of the River Loxley and lies in cascade above Dale Dike and Damflask reservoirs. It is an earth embankment dam completed in 1869. Agden reservoir is situated on an adjacent valley to Strines and was also completed in 1869, following a redesign after the failure of the original Dale Dike dam in 1864. Following recent recommendations made in the interests of safety at both reservoirs, hydraulic models of the spillways were constructed for the probable maximum flood (PMF) outflow of 150 m³/s at Strines and 135 m³/s at Agden. The models showed that there would be significant out-of-channel flow from the spillways, which could pose a threat to the embankments. The models also showed that the peak stillwater flood level was above the embankment crest at both reservoirs such that the existing wave walls would have to retain the PMF flood rise. This paper describes the design and construction works that were carried out at both reservoirs between 2006–2009, which included new wave walls and significant spillway modifications. The solution for each site was unique owing to site constraints and topography. A number of innovative construction solutions were used including a masonry effect formliner used on in situ concrete walls, and precast concrete wave wall sections that were then clad with existing masonry. The challenges of delivering a cost-effective solution were met while complying with the aesthetic requirements of the Planning Authority.

An apparatus is described which deposits dry sand over a wide range of porosities. It has been used to prepare beds of sand in a 3 ft diameter container for a series of model pile experiments. Direct measurement of porosity and the results of model pile tests show that the bed is homogeneous and the resulting porosity is reproducible.

On décrit un appareil qui dépose du sable set sur une gamme étendue de porosités. On l'a utilisé pour préparer des couches de sable dans des récipients de 3 pieds de diamètre pour une série d'experiences modèles de pieux. La mesure directe de porosité et les résultats des essais modèles de piéux montrent que la couche est homogène et la porosité obtenue est reproductible.

This paper describes an investigation undertaken to study the development of stable bulging in drystone retaining walls using a two-dimensional plane strain distinct element numerical model. Development of the numerical model, informed by field study investigations and material tests from a case study wall, is presented. A parametric study of the influence of backfill properties, wall block properties, wall joint properties, and wall geometry on stability is then briefly outlined. Three-dimensional aspects of bulging in drystone retaining walls are also discussed. Stable bulging failure is simulated in a plane strain distinct element model using tapered blocks and a voided porous wall structure. This behaviour is validated using a simple limit equilibrium analysis. The extent of bulging under simulated surcharge loading is shown to be dependent on model stiffness, which is influenced by wall and fill material properties, voidage in the wall, and masonry bonding.

This paper presents experimental results from an ongoing study investigating the flexural bond strength, initial shear strength and compressive strength of brickwork built using natural hydraulic lime mortars. All tests were conducted in accordance with relevant standard procedures. Flexural bond strengths, with planes of failure parallel and perpendicular to bed joints, were determined by panel (wallette) tests. Bond wrench testing of stack-bonded prisms was also conducted to investigate further the material influences on flexural strength. The main parameters studied in this investigation were mortar mix design (binder : aggregate ratio; lime grade) and brick water absorption characteristics. The flexural bond strength and initial shear strength of the brickwork in general increased with mortar strength, but flexural bond strength was significantly impaired by both low and high brick water absorption. The bond wrench test was found to be a reliable, quick and easy, alternative test procedure to determine flexural strength (with plane of failure) parallel to the bed joints.

A limit-equilibrium analysis program has been developed as part of an investigation into the stability of drystone retaining structures. Initial verification of the program's function was in relation to field trials conducted in 1834 by Lieutenant-General Burgoyne, which have been the main reference to date for checking numerical modelling of drystone retaining walls. Parametric studies and investigations of bulging mechanisms are reported and analysed. Program predictions have been compared with the initial results from new small-scale and full-scale drystone retaining wall tests.

This paper deals with research undertaken at Oxford Brookes University into the bond strength of deformed bars set in normal-weight concrete. It briefly describes pull-out tests on some 150 specimens (providing 300 results), in which the variables were the position of the bar during casting, lateral pressure, cover, bar diameter, concrete strength and bar spacing. The results of the tests are compared with the values predicted by the British and European Codes of Practice BS 8110, Eurocode 2 and CEB-FIP Model Code 1990. Generally, the British code is shown to be very conservative and to underestimate the bond strength. However, when the bars have low cover-to-diameter ratios or where the bars are spaced in pairs vertically, the code appears to give unsafe values. The European codes provide better predictions of the bond strength because they take account of the majority of the influencing factors. However, they do not adequately account for the variables over the full range and are conservative in many circumstances, particularly when lateral pressure is applied. An alternative design procedure is proposed which is based on the experimental evidence and takes account of the main factors influencing the bond.