Abstract:

The jet grouting method is commonly used for ground improvement. However, little is known about its actual improvement structure in the ground. The extent of improvement, such as the size of effective grout diameter and the degree of overlapping is still in question, especially for complicated ground conditions such as ground with different soil strata. This paper presents the actual findings of the condition of improved ground by jet grouting method, from a tunneling site. It was observed that preceding grout column had a near circular shape, and that they interlocked with the adjacent grout columns, hence meeting the ground improvement requirements. In the evaluation of ground improvement by jet grouting, the compressive strength test is generally employed by means of the boring core specimen, which can be obtained as a test cylinder. However, the ground improvement without such improve condition is estimated to be able to support a certain extent of load. The purpose of this study is to establish the evaluating criterion of condition of jet grouting, and to propose the evaluation method for ground improvement.

Key words:  , jet grouting method  , ground improvement  , actual condition