In this report a class `a' prediction for the behaviour of the instrumented section of one of the retaining walls of the bell common cut and cover tunnel on the M25 motorway at Epping, Essex is presented. This prediction is based on complex finite element calculations simulating the construction procedure and assuming the soil to behave in an elasto-plastic manner. Predictions of wall displacements and bending moments, soil movements and total horizontal stresses in the soil are presented. These are given at the proposed locations of the measurement stations to be employed in the field instrumentation and will therefore ease later comparisons between predictions and field observations when the latter data becomes available. In addition, a parametric study investigating the sensitivity of the analysis to the input assumptions is reported. The predictions have been made well in advance of completion of tunnel construction. (Author/publisher)
Samenvatting