A behavior measurement and evaluation of geostructure are very important to ensure a long term stability of geostructures. This study is to propose spiral bolt strain gauge as measurement tool of geostructures, and to evaluate applicability of spiral bolt strain gauge to the soft ground foundation and rock slope. In the behavior of soft ground foundation, the strains showed a stable state in the initial measurement, and then a significant change. It is considered that the change was relaxed the ground due to the increase in rainfall and frequent earthquakes with low magnitude, and then was subsequently caused the behavior of ground. In the behavior of rock slope, the strains showed the extension at a point of the upper to middle and the compression at the bottom. Overall strains were observed a very little change during 0 ~ 50 days, the largest change at P6 during 50 ~ 100 days, and a stable state except p6 during 100 ~ 160 days. The change might be caused by blasting for the excavation of limestone mine affected the largest on P6. In conclusion, the proposed spiral bolt strain gauge can be useful to measure the behavior of geostructures and also to be applied to the reinforcement of geostructures.
Mechanical properties of materials uses as an important input data to predict the deformation behavior and collapse of geostructures such as soft ground foundation or rock slope. The tools of various types for measuring the behavior of geostructures have been used currently. For example, direct measurement methods can be directly observed the deformation behavior on the target surface of in-situ ground. In addition, other measurement methods such as buried type displacement gauge or strain gauge is considered to be beneficial method in order to measure the overall behavior of the ground. Various methods such as surface settlement gauge, continuous settlement gauge, cross-arm settlement gauge, and so on are suggested for measuring ground behavior1. However, these methods are not easy to apply to a site because they are difficult to install in geostructure as well as hard to monitor it for a long time. Accordingly, a new type tools, including the advantages of economical efficient, applicability and conservation for measuring geostructure behavior are required. This study is to propose spiral bolt strain gauge as measurement tool of geostructure behavior, and to evaluate applicability to the soft ground foundation or rock slope. Spiral bolt strain gauge can be used for reinforcement of geostructures because of high pull-out resistance, and also is useful measuring geostructure behavior because of structural flexibility2. Accordingly, if spiral bolt strain gauge is apply to geostructures, reinforcement and behavior measurement of geostructures may be made together. Spiral bolt strain gauge for measuring geostructure behavior has the following characteristics, comparing with other measuring tools. Firstly, this instrument is inexpensive and economic. Secondly, it is easily installed at a site. In addition, the measuring method is simple, therefore it can be reduced time consuming works from installation to measurement.
