No abstract

Labiles Waterglass Grouting(LW Grouting) is one of the ground improvement methods to protecting water leakage and reinforcement in underground structures. Some of central columns of an underpass are damaged during injection of grouting liquid which is to improve loose soil for the construction of tunnel directly across beneath the underpass. Three dimensional analysis are performed with construction stages including the construction of underpass, the excavating of construction base and LW grouting to investigate the grouting influences to the underpass and the cause of damage. Even though the injection pressure of LW grouting is relatively low to the other grouting methods, the injection pressure is directly affect to the underpass while the bedrock layer which confine the pressure. The columns of underpass are damaged by shear force since the grouting arrangement is curved and the lateral component of injection pressure occurred. To improve the LW grouting effect and avoid similar pattern of accident, it is necessary to take account the injection pressure in primary design stage, grouting arrangement and injection order to prevent the unequal upheaval.