Ground improvement work with N-value estimation by measurement of current value

Abstract

In recent years, the demand has been increasing for ground improvement work for seismic reinforcement and as a countermeasure to liquefaction utilizing Information Construction Technology, Internet of Things, and Building Information Modeling. Therefore, it is expected that more and more attention will be paid to construction management related to the quality and work progress of the soil improvement body as the demand for ground improvement work increases. On the other hand, since the actual ground is assumed to be heterogeneous in geological composition and soil quality, the thickness of the layer that will be subjected to the ground improvement work and the depth to the bearing stratum may be different from those assumed at the design stage. In addition, since the number of ground surveys that have been conducted for ground improvement work is limited, it is not easy to promptly evaluate the validity of actual construction specifications against the design values of the improvement body in locations far from where the ground surveys were done. Therefore, in order to solve the above problems, this study addresses the current value measured and recorded during construction by the deep mixing method, which is one of the ground improvement methods. Approximation of N-value that is a strength index of the target ground is examined, considering the correlation between the current value and the N-value obtained from the standard penetration test (SPT) conducted in the preliminary ground survey. In addition, the applicability of the estimated N-value to an actual construction is examined by formulating an N-value approximation. Based on the obtained current value, this study clarified to possible to formulate an approximation for the N-value and to use this information as feedback at the time of construction.