The liquefaction of tailings is a common failure mode under earthquake actions. The traditional treatment measures of waste rubber have the disadvantages of environmental pollution and occupying soil resources. The combined treatment of waste rubber and tailings is very likely to have important engineering application and theoretical value, and the dynamic characteristics of the rubber-tailings mixture (RTM) are essential and indispensable for handling them together. In this paper, the dynamic triaxial test was used to study the dynamic mechanical characteristics of the RTM. The test was divided into 5 groups with 54 valid samples. The effects of the rubber particle size, rubber content, consolidation pressure, pH value, and soaking time on the dynamic characteristics of the RTM were studied and discussed. The results show that the liquefaction cycle number of the RTM is 50% higher than that of tailings, and the particle cluster effect theory of the RTM is put forward. It will provide a theoretical basis and guidance for the treatment of the waste rubber and tailings.

The traditional bored pile technology has some arduous problems, such as the sediment at the pile tip, the mud skin along the pile shaft, and the stress release due to borehole construction. The post-grouted technology at the pile tip of bored pile has emerged because of demand. The grouting migration height (GMH) is of great significance to the strengthen and reinforcement of the pile foundation. This paper derives the calculation formula of the GMH based on the theory of the column hole expansion and Herschel-Bulkley model. The influence of relevant parameters on the GMH is discussed. Aiming at the problem of the grouting migration along the pile shaft in layered soils, the iterative calculation method of the GMH is proposed. The correctness of the GMH is verified by an engineering case, which can guide the engineering practice. The result shows that the GMH increases with the increase of the grouting pressure, the pile diameter and the thickness of the mud skin, and the grouting pressure is positively correlated with the GMH. The GMH decreases with the increase of the buried depth, the consistency coefficient and the rheological index. On this basis, the correctness of the GMH is verified by an engineering case.