Study and Application of Similar Material Ratio in Collapsible Loess

The similar material of collapsible loess is the basis and premise of the experimental study on the surface movement and deformation law of coal seam mining in collapsible loess-covered areas. The orthogonal experiment is used to make up similar material with different proportions using river sand and barite powder as aggregate, clay and gypsum as cementing material, and diatomite as adjusting material. The reasonable proportion of similar material in collapsible loess is studied by using range analysis, similar simulation, and field measurement. The results show that the content of diatomite plays a leading role in the collapsibility coefficient of similar material, and the collapsibility coefficient is positively correlated with the content of diatomite; moisture content is the main control of the cohesion of the material, and cohesion is negatively correlated with the moisture content; the ratio of bone-to-glue has the most significant effect on the internal friction angle, and the internal friction angle is positively correlated with the ratio of bone-to-glue. The reasonable ratio of the similar material in collapsible loess is 8 : 2 of the ratio of bone-to-glue, the ratio of clay-to-gypsum is 9 : 1, the barite powder content is 6%, the diatomite content is 23%, and the moisture content is 13%, and the mechanical parameters of the collapsible loess are 5.3%–6.3% different from the target value of similar material through laboratory tests, which can meet the experimental requirements. It is verified by a similar simulation experiment that the maximum surface subsidence value and the surface fracture width in the simulation results are 6.9% and 7.8% different from the field measured results, indicating a high degree of agreement. The results of the study have important references and guiding significance for the preparation of similar material with similar models.

Study on the Hydro-Thermal-Mechanical Characteristics of the Lime-Soil Compaction Pile in the Forming Process

To study the effect of the lime-soil compaction pile on the collapsible loess foundation and the influence of water-heat-force characteristics on the soil during compaction, the field test of lime-soil compaction pile treatment of collapsible loess foundation is carried out. This paper monitors the process of soil temperature, water, and soil pressure change in the process of pile forming. According to the macroprocess and micromechanism of lime-soil compaction pile treatment of collapsible loess foundation, the qualitative law of water-heat-force change in the process of pile forming is obtained. Meanwhile, the influence of soil damage is introduced in the process of compaction expansion. The model of pore expansion under linear damage conditions in the plastic zone is established. The formula of radial stress distribution under damage conditions is given. The influence of different damage factors on the expansion process is analyzed.

Application of Controllable Splitting Grouting Technology in Loess Foundation Reinforcement

Taking the foundation settlement accident of a large heating boiler foundation in a city in collapsible loess area as an example, controllable splitting grouting can be achieved by controlling the grouting pressure, grouting pipe opening form, grouting volume and grouting method etc., so as to stabilize foundation settlement and improve foundation bearing capacity, for the boiler with large uneven settlement, for boilers with large uneven settlement, quicklime piles are used to jack up the foundation after splitting grouting to stabilize the foundation, the foundation is lifted with quicklime piles after splitting grouting to stabilize the foundation. The results show that the grouting amount of soil is within the design range, the grout splits in the soil several times to form a slurry vein, the settlement is stable after boiler reinforcement, the quicklime method can jack up the foundation and reduce the uneven settlement of the foundation, and the use of controllable splitting grouting can basically eliminate the slight collapsibility grade loess, which provides a new idea for solving the similar problem of uneven settlement of collapsible loess foundation buildings.