An Experimental Study On The Variety Law Of Mini-Scale Structure About Marine Soft Soil Under Different Occurrence Environment

The occurrence environment of marine soft soil in coastal areas has been changed tremendously by the large scale of reclamation and its subsequent constructive activities. In order to study the variety law of mini-scale structure characteristics about marine soft soil under different occurrence environments, the typical marine soft soil obtained from bonded port area in Qinzhou harbor was used as study object, and with an approach of sample preparation under simulated conditions, which to study the mini-scale structure characteristics of marine soft soil and its variety law under different occurrence environments from micro structure level by the apparatus such as scanning electron microscope and mercury porosimetry.In this paper, the main research results are as follows:1. Based on the research of changing occurrence environment with respect to marine soft soil before and after reclamation, two main changing factors with large areas of surface load and chemical constituent of pore solution were highlighted in this paper,20groups of changing combination with environment elements has been laid out, and the self-made soak-loading equipment were taken use of, artificial samples imprinted with environment changing elements were prepared successfully while simulating the changing of environment.2. A mercury intrusion porosimtry (MIP) test was carried out with the prepared samples which were made by Lyophilization and Displacement drying method, the criteria for classifying of soil mass was designated, and also analyzed pore characteristics of prepared samples along with the variety law of occurrence environment, the experiment results showed that:samples made by lyophilization had smaller perturbation, however, samples made by Displacement drying method had bigger shrinkage, it is better to take use of Lyophilization to prepare samples for pore test; when in the same soak solution, porosity ratio of the samples decreased gradually along with the increase of overlying load, the percentage of larger-scale pore (such as big、middle pore) went down, however, smaller-scale pore (as micro、super micro pore) went up, larger-scale pore turned to smaller-scale, and smaller-scale pore took in dominance eventually; when under the same overlying load, larger-scale pore under the action of overlying load was easier being crushed into smaller pore with higher ion concentration of soak solution.3. The loaded section of prepared samples were scanned by using SEM, some relevant images of SEM were obtained and also been qualitative analysis.4. The SEM images were under digital processing by using IPP, an image processing and analysis software, and the parameter of particles’ mini-scale structure characteristics were extracted, furthermore, the variety law under different occurrence environment were analyzed. It has been found that:when it was in the same soak solution, the larger the load was, the proportion of small particles decreased gradually, while the proportion of big particles increased, also the average grain size grew up gradually, the particles average roundness became larger and larger, the aggregation level of particles were higher; when in the same pressure, the aggregation level of the samples, which soaked in the solution with2.5%concentration of Ca2+or Mg2+, was lower than it was soaked in the solution with0.25%concentration of Ca2+or Mg2+and it was in the original sea water.5. An initial analysis was taken on the structural strength of marine soft soil under different occurrence environment from a mini-scale structure perspective.