Study On The Solidified Technology And Mechanism For Hydraulic Fill Of Tianjin Inshore New Developed Area

With the rapid economic development of Tianjin Inshore New Development Area and the construction of Tianjin harbor sea-route engineering, offing fresh deposit seabed silt is used to besiege the sea to obtain land as hydraulic wad lately. The dredger fill is formed under hydraulic dredging, characteristics of fine particle and weak in consolidation capability with slow natural sedimentation and consolidation process, and it takes a long time to achieve the consolidation completely. Only when the surface duricrust has formed , should the ground improvement treatment be started, but it is high-cost and lasting-time to reinforce the dredger fill groundwork at present. So it is necessary to seek a more economical and reasonable method to make the dredged mud become an integrated part of the ground with certain bearing capacity as quickly as possible. In this thesis, the hydraulic fill in Tianjin Inshore New Development Area is studied, and soil stabilizers were added in the dredger fill to accelerate the consolidation. The solidifying mechanism has been demonstrated through lab test and analysis of the effect of the treatment, and a method to consolidate the foundation of dredger fill is presented.First, the physical property, chemical composition and mechanical property of hydraulic fill in Tianjin Inshore New Development Area are studied based on the test. It is found that the hydraulic fill in Tianjin Inshore New Development Area is predominated by fine-grained soil and belongs to unfavorable gradation, has strong compressibility, low strength and poor permeability.Second, one type of soil in Tianjin Inshore New Development Area and several powdery stabilizers were selected in the experiment. Two soil stabilizers A (cement is primary component and sodium carbonate is assistant) and B (cement is primary component and PAM is assistant) were chosen according to the strength increase, the ratio of the capability and the price. The results as follows:(1)The unconfined compressive strength of the stabilized soil was improved more than 20% when adding 0.3% to 0.5% sodium carbonate or adding PAM for the stabilizer compared with cement soil. The 30d's strength could achieve more than 0.6 MPa and 60d's strength could achieve more than 0.9 MPa when the proportion was 0.5%.(2)The proportion of sodium carbonate or PAM has a definite extension. The unconfined compressive strength of the stabilized soil would debase with the augment of the proportion of sodium carbonate or PAM when the proportion was more than 0.5%.(3)The cement, the proportion of the stabilizers and the moisture content were the most factors to the unconfined compressive strength.Third, electronic scanning microscope is used to obtain the microscopic scanning picture of hydraulic fill, and picture processing software is used to obtain the micro-structure parameters. Equivalent diameter, number of void, perimeter of void, area of void, shape ratio of void and roundness of void are selected to impress the size and shape of void in hydraulic fill. Ulteriorly we simply discuss the solidified mechanism of hydraulic fill.Finally, we get a optimization project from the economic comparing of several treatments for hydraulic fill by fuzzy mathematics opinion.