This paper investigates the feasibility of bio-stimulation for sand fixation and dust prevention[1] in the Taklimakan Desert region. Field-scale tests were conducted on man-made cone dune and trapezoidal sandy structure[2]. A specialized stimulation solution and a cementation solution were applied to both soil structures according to a prescribed spraying method and frequency[3]. Following treatment, the surface bearing capacity, crust thickness, and wind erosion resistance of the specimens were assessed. Additionally, the microstructural and compositional changes of the samples before and after treatment were analyzed. The results indicated that the bio-stimulation method significantly enhances the bearing capacity and wind erosion resistance of desert soil by forming a crust on its surface layer. Considering time and cost factors, D(1+1) or T(1+1) processing may represent the most effective scheme for future large-scale applications. Microscopic tests (SEM, EDS) further confirmed the microbial curing mechanism, revealing that as the number of sprays increases, the calcium content and strength of the soil also increase. Moreover, a positive correlation was observed between the solidification strength of desert soil and crust thickness[4]. This conclusion provides a reliable foundation for implementing sand fixation and dust prevention strategies, mitigating sandstorms, and improving climatic conditions in the Taklimakan region in the future.

The concrete of bored piles and diaphragm walls is often placed via tremie pipe to minimize segregation and mixing with bentonite suspension. The design and performance of self-compacting concrete often needs to meet the competing requirements for workability and stability, i.e. resistance against segregation and bleeding. Excessive bleeding in fresh concrete may give rise to channels and cavities impairing the quality of deep foundations. This paper summarizes our works on the bleeding of fresh concrete in the past decade. These works include the filtration test for bleeding propensity, the early strength of fresh concrete in a large shear box, the in-situ stress state in bored piles during and after placement and the centrifuge tests on model piles of fresh concrete. Finally, a mathematical model for the bleeding in deep foundation is established, which allows a solution in form of solitary waves. The solution offers a convincing explanation for bleeding mechanism. Some field tests are carried out on a bored pile with a diameter of one meter and a length of 5 meters. The test results are used to validate our mathematical model.