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Heavy metals are not only hazardous to environment and public health, but they degrade the physicochemical and biological properties of soils increasing difficulty to the redevelopment of contaminated sites. This study proposes a method for reinforcing contaminated soils with fiber and cement. The feasibility of using wheat straw as fiber reinforcement is discussed. The strength of heavy metal-contaminated soil reinforced with wheat straw and cement is investigated through laboratory testing. Twelve groups of soil samples were prepared at three fiber contents (i.e., 0.1%, 0.2%, and 0.3% by weight), three water contents (i.e., 9%, 12%, and 15%), and three cement contents (i.e., 5%, 7.5%, and 10% by weight). Unconfined compression strength (UCS) was tested after 28 days of curing period and various freeze-thaw cycles. The testing results show that the increase in the number of freeze-thaw cycles results in the decrease of UCS. The inclusion of fiber reinforcement within cemented soil causes an increase in the UCS and changes the brittle behavior of cemented soil to a more ductile one. The UCS of the fiber-reinforced soils first increases, then decreases with the increase of water content, and reaches the maximum value at the optimum moisture content.

One steel grid and five thin-walled concrete-filled steel tubes (CTST) used as the supports of tunnel were tested in site for investigating the mechanical behavior. The mechanical influences of thickness, node form, and concrete on CTST were gained and compared with the impacts on steel grid. It is indicated that high antideformation capacity of CTST improved the stability of surrounding rock in short time. The cementitious grouted sleeve connection exhibited superior flexibility when CTST was erected and built. Although the deformation of rock and soil in the tunnel was increasing, good compression resistance was observed by CTST with the new connection type. It was also seen that vault, tube foot, and connections were with larger absolute strain values. The finite element analysis (FEA) was carried out using ABAQUS program. The results were validated by comparison with experimental results. The FE model could be referred by similar projects.