| dc.description.abstract | Shield machines are used frequently in tunnel construction works of rapid transit system in Taiwan or foreign countries. The soft soil layer around the construction shaft usually needs to be improved to prevent construction disasters during the shield machine passes through the slurry wall. In the other hand, many deep excavations of soft ground were performed for constructing new buildings. In order to prevent heaving of ground, to decrease settlement of ground surface or to increase strength of soil, the soft soil at both sides of retaining wall should be improved also. Jet grout method is a useful method for ground improvement. Although this kind of improvement is helpful to the construction work, but the jet grout composite ground maybe unstable before the cementing of jet grout columns.
To investigate the stability of composite ground with uncemented jet grout columns, this research tried to use FEM program ABAQUS to carry out a series of numerical analysis. In this analysis, it is supposed that a new jet grout method SJM, i.e. Super Jet Midi, is used. From the results of the analysis, it is shown that a larger settlement of ground surface will occur for three jet grout columns which were not cemented. For the condition of small overburden layer, a larger settlement of ground surface will occur, but its influence area is smaller. Furthermore, a smaller settlement of ground surface will occur for the soil layer with higher strength of soil. Therefore, for the consideration of safety, it is suggested that the jet grout columns should not be set in succession. | en_US |