No abstract

Combining two or three shield tunnels that are drilled consecutively at small intermediate distances into a single open cross section creates a larger useful tunnel area, while keeping the total construction area rather compact. However, the combination of several bored tunnel tubes into a singular cross section results in a complicated construction procedure. Current methodologies address the evaluation of the settlement trough for one single tunnel or two parallel tunnels only. This study aims at expanding the current methodologies to the multiple-tunnel geometry. Various construction orders and intermediate distances between the tunnels are evaluated using finite element analyses. The grout pressure method is applied in combination with the hardening strain with the small strain stiffness (HS small) constitutive model to investigate the relative magnitude of the settlements due to shield tunneling. It is concluded that the configuration with a Top-Left-Right construction sequence is the optimal arrangement. It results in 22.4% and 36.9% lesser settlements when compared to the equivalent horizontal twin tunnels spaced at 3D and the Left-Right-Top sequence, respectively.

<p>Reaching Brussels Airport by car or by train from the Northern part of Belgium has become difficult. For this reason, a new railway connection is being built below this airport. The new link will connect the existing train station to a new 24 km long railway section from Brussels to Mechelen, located in the central reservation of the motorway between these two cities. The most important part of the connection is a 1084 m long twin tube bored tunnel, passing below the runway and taxiways. Because of this, an adequate design load for aircraft actions had to be chosen, which complies to modern aircraft characteristics. Particular attention is given to the boring of tunnels below an aircraft maintenance hangar with pile foundations. Although passive protective measures are taken to prevent damage to the building, an accidental loading case of concentrated pile loads on the tunnel lining must be considered. In addition, concrete cracking of lateral diaphragm walls of the cut and cover sections of the new railway tunnels is being considered.</p>

In this case report, the diagnosis and ultrasound-guided retrieval of an intravaginal grass awn in a dog and a cat are described. The dog was presented with chronic vaginal discharge for over two years. The cat was presented for acute lethargy and bloody vaginal discharge and a two-week history of a perivulvar leakage. Ultrasonographic diagnosis included the visualization of a linear, hyperechoic and spindle-shaped structure and mild thickness of the vagina. The grass awns were successfully retrieved non-invasively, under general anesthesia using ultrasoundguided Hartmann forceps inserted into the vagina. Ultrasound-guided grass awn retrieval from the vagina appears to be a safe and inexpensive procedure.

<p>During a period of several years, temperature variations have been monitored at several points of a cross section of the Vilvoorde Viaduct, which is one of the most important steel box girders of the Belgian highway network. Analysis of the monitoring data indicates that substantial temperature variations exist, during a 24-hour cycle of heating and cooling. Values of more than 30 degrees or more are found to be quite common. In addition temperature gradients have been measured of more than 20 degrees between both sides of the steel box girder, which could result in additional displacements and warping of the cross section.</p><p>Although thermal loads are not often considered during the first design steps of steel box girders, their influence can be quite substantial. When the thermal loads and more specifically the thermal gradients within the steel box girders reach considerable values, a number of other effects are influenced. High thermal gradients will reduce the cohesion of waterproofing layers and wearing courses, thus reducing the composite behaviour of these layers with the deck plate.</p><p>Hence, the quantification of the thermal loads working on steel box girders becomes quite important. While this was previously done using detailed finite element models, including solar radiation, cooling, convective airflow, etc. this research paper will give tangible design values for thermal gradients in steel box girders, based on actual measurements, which are in some cases higher than those values given by the current design codes, especially when looking at the temperature difference between two points of the same cross-section.</p>