Preliminary Research in the Mechanical Properties of the Fault Gouge

• Main Authors: Shen Jian Jr, 沈建志
• Other Authors: Lin Ming Lang
• Format: Others
• Language: zh-TW
• Published: 1995
• Online Access: http://ndltd.ncl.edu.tw/handle/31260743485051080577

碩士 === 國立中央大學 === 應用地質研究所 === 83 === Fault zones are the weak zones resulted from extreme shearing disturbance in the strata, and fault gouges of different thickness are often contained. With the influence of ground water and stress state on its properties, fault gouges always causes disasters in the process of engineering construction. There exists very much close relationship between such disasters and the the properties of high swelling pressure and gradually softening of the fault gouge as a result of absorption of moisture and stress relief. However, that the reason why there exists characteristics of high swelling in the fault gouge of major fault zones and what the main causes are is really concerned. Due to not containing pronounced expansive clay minerals and the characteristics of overconsolidation and diagentic bond, the experienced rules commonly used in the evaluation of swell potential of expansive soil is not complete applicable to the fault gouge samples in this research. The record of unloading process in the consolidation test reveals that the higher the overconsolidation ratio(OCR), the higher the secondary swelling index, and the lower the coefficient of swelling. The phenomenon of secondary swelling is more pronounced with time passing. It may be deduced that high OCR occurs in the fault gouge owing to unloading condition during tunnel excavation through major fault zones under high overburden pressure. Therefore, the secondary swelling is more pronounced with time passing. Although nothing particular is observed in the short term, the tunnel is gradually squeezed and deformed to the end of destruction in the long term. The reason why the value of c'' is different between the two fault gouges described above is possibly related to the degree of weathering, and φ'' is possibly related to the strain rate and the number of foliation in the same sample size.