Soils deform as a function of time because of the consolidation and the creep processes. Under undrained conditions, the consolidation process is prevented and the creep deformations are isolated. A series of unconsolidated undrained (UU) triaxial tests were conducted to investigate a creep deformation model and a creep failure model. The creep deformation model estimates the deformation as a function of time for a sustained stress level. It is a simple power law able to describe the creep measurements observed in the experiments. The creep failure model predicts the approximate time for the creep failure to occur under a sustained stress level. It is based on a strain-failure concept in which the failure time is defined as the time necessary to reach the failure strain. The main model parameters are the creep exponent and the strain to failure, which can be obtained from creep triaxial tests and from standard triaxial experiments, respectively.

The debate on creep in primary consolidation is analysed with a power law model following an approach in which creep is considered as rate of loading. According to this approach, primary consolidation is one type of rate of loading. To verify this approach, two types of tests, standard oedometer test and oedometer test with drainage prevented, are conducted on three types of soils (two from NGES and the other from Port of Guangzhou). The result: creep exponents obtained from two kinds of tests agree well with each other. Moreover, the approach is further validated by tracking, for over 80 years, the data from settlement of the case history San Jacinto Monument, which is inconsistent with data calculated from the classical method. In the end, procedure of this approach, with which long term settlement is predicted, is illustrated, and this approach is compared with the classical method.

Segmental stress during the construction process plays a pivotal role in assessing the safety and quality of shield tunnels. Fiber Bragg grating (FBG) sensing technology has been proposed for tunnel segment stress monitoring. A laboratory test was conducted to validate the reliable strain measurement of FBG sensors. The field in situ monitoring of a sewerage shield tunnel was carried out to examine the longitudinal and circumferential stresses experienced by the segments throughout the construction phase. The cyclic fluctuations in stress were found to be synchronized with the variations in shield thrust. A comparison was made between the longitudinal and circumferential stress variations observed during the shield-driving and segment-assembly processes. Additionally, the time required for the grouting to reach its full curing strength was estimated, revealing its impact on the stress levels and range of the pipe segment. The findings of this study offer an enhanced understanding of the stress state and health condition of small-diameter shield tunnels, which can help in optimizing the design and construction process of tunnel segments, as well.