Study of formwork pressure of wall under ultra-deep vibration

In order to design vertical formwork, an accurate model to predict the lateral pressure of fresh concrete is needed in construction practice. However, there have been few studies on the lateral pressure of concrete walls subjected to ultra-deep vibration and great differences exist on the determination of form pressures and vibration depth in the current national codes. This paper reports a test of four concrete wall specimens that was carried out to study the effect of ultra-deep vibration on the lateral pressure of fresh concrete and the distribution of lateral pressure at various heights of concrete walls. Based on the vibrating liquefaction and hydrostatic pressure balance theory, a calculation model of the lateral pressure of concrete under ultra-deep vibration is put forward, together with a derived formula for simplified calculation. The predictions of the model are compared with the experimental results, and it is shown that the proposed model is able to explain the experiment observations and predict with reasonable accuracy the lateral pressure in fresh concrete walls subjected to ultra-deep vibration.