The Study On Strength Mechanism And Engineering Application Of Cement Soil Mixed With Seawater By Adding Short Fiber

With the rapid development of the global economy and urban construction, land area is decreasing, especially agricultural land. For the sake of the further development of agriculture, ocean exploitation has gradually become the important strategy for countries all over the world as well become a crucial guarantee in facilitating world economy development. An increasing number of coastal engineering has sprung up, however, there are many weaknesses in the engineering and building which are constructed on the soft soil. Hence, this study further designed the relevant strength experiments based on the original basis. The results showed that expansion and strength of cement soil mixed with seawater by no adding short fiber interpreted that the sea water and alkaline salt only enhanced sightly the cement soil strength, but inevitably leaded to the rise of soil expansion. As time gone on, no load P0 and load P1 group expansion rate showed a clear increasing trend, whereas load P2 group expansion rate unchanged maintaining around the basic line. The curves of the tensile strength, compressive strength and bending strength all illustrated an increased tendency with the consolidation time, also the value of tensile strength was lower than compressive strength and bending strength. Therefore, cement soil only mixed with seawater could improve the strength, but the effect is considerably limited.When adding the short fiber into the cement soil, the expansion could be inhibited effectively, and showed the three stage rules of "growth-- stability--growth" because the adhesive force between particles and fibers and soil exist the relationship of "increase-- stability-- down". There exists an optimum adding amount between the ratio and length of fibers in a soil sample. In this paper, the most optimal amount of adding is 0.1%-10 mm. In the soil strength, adding short fiber can greatly improve the tensile strength, effectively enhance the compressive strength and boost bending strength to a certain extent. The intensity change was related to the the fiber length and proportion. Eventually, the interaction between single fiber and soil particles reflected the macroscopic changes after adding the fiber, which leaded to the strength increased initially and then decreased.From the analysis of the electron microscopy, the change of cement soil strength was most related to the internal friction. Particularly, the reason why cement soil strength raised firstly after adding the fiber was that the fiber surface was full fill with "wire or filament". Later, the strength increased weakly even the strength declined may be relative to the decreased adhesion friction and compactedness between fibers and soil particles. The author preliminary painted a variation pattern of the tensile strength, bending strength and compressive strength, briefly explained the source of the force and the reason of strength decline, which contributed to the further study on the fiber reinforced soil constitutive model. Finally, this paper briefly discussed the principle of key technology on cement soil mixed with sea water by adding short fiber and the construction method of mixing pile adding the short fiber on the soft foundation. Combined with the characteristics of Zhoushan Island, the author drew the construction process, took modern Jun yuan residential area of the foundation pit engineering as an example, and briefly narrated the application situation of seawater slurry mixing cement soil in Zhoushan and the analysis of technology, as well as the operation instructions and relevant beneficial analysis. All the findings will provide practical guidance for the future to promote the application of short fiber seawater slurry mixing cement soil.