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In recent years, construction works near the operating metro tunnel in granite residual soil have been gradually increasing, and the impact of these construction works on the safety of shield tunnel should not be ignored. Finite element method is an effective method to evaluate the influence of adjacent construction on shield tunnel, but its reliability highly depends on the reasonable selection of soil constitutive model and parameters. In this paper, the current situation of parameter selection of hardening soil model for granite residual soil is firstly reviewed. Then a back-analysis method for determining the parameters of granite residual soil based on the self-boring pressuremeter test (SBPMT) is proposed. Finally, the obtained back-analysis parameters are applied to the engineering case of foundation pit excavated overpass existing shield tunnel for method verification, and more reasonable values of parameters of hardening soil model for granite residual soil are determined. The results show that the strength parameters of hardening soil model for granite residual soil can be determined by laboratory tests, and the stiffness parameters of E50ref, Eoedref and Eurref are the key parameters for the back-analysis. The ratio of E50ref: Eoedref: Eurref from 1:1:3 to 1:1:5 is suitable for engineering practice, and the value of E50ref ranges from 36 MPa to 43 MPa according to different ratios.

Bumblebees play an important ecological economic role as pollinators in nature and agriculture. For reasons of biosecurity, many countries promote the cultivation of native bumblebee species for crop pollination instead of importing "alien" species. In South China, a few bumblebee species are considered useful in this way, particularly, Bombus atripes, Bombus bicoloratus and Bombus breviceps. However, whether they are suitable for artificial rearing and forming healthy colonies for pollination, remains unknown. In this project, queens from the 3 native species of Guizhou Province were collected and colonies were started under standardized conditions. The colonies were scored based on 19 parameters, including the stage of colony development, number and weight of offspring, and diet consumed. The data revealed that B. breviceps had the best performance, produced more workers and consumed the smallest diet. Next, we performed 16S rDNA sequencing of the bacterial communities found in the guts of offspring workers, and then a correlation analysis between colony performance and gut bacteria was conducted. Here, B. breviceps showed the highest diversity in gut bacterial composition, dominated by the bacteria Gilliamella, Snodgrassella, Enterobacter, and Lactobacillus Firm5. The higher the abundance of Snodgrassella, the better the performance of the colony in the foundation stage, and later Lactobacillus Firm5, Apibacter and Bifidobacterium were beneficial during the stages of rapid growth and colony decline. Although we do not understand all of the interactions yet, these correlations explain why B. breviceps demonstrated better colony performance. Our data provide valuable information for breeding local Bombus species and will contribute to developing strong colonies for crop pollination. [ABSTRACT FROM AUTHOR]

This study evaluates the shadowing effect of existing tunnels on the evolution of soil arching, focusing on the shape of the tunnel (circular and rectangular) through trapdoor experiments. The displacement and shear strain distributions of ground soil resulting from trapdoor movement were estimated using a digital image correlation technique. The results showed that the shadowing effect of the rectangular tunnel was significantly greater than that of the circular tunnel of the same size. The sand above the tunnel was displaced in a double-groove pattern owing to the presence of the tunnel, and the maximum surface settlement occurred between the tunnel boundary and the trapdoor edge. The circular tunnels exhibited consistently higher maximum surface displacements than that in the rectangular tunnels. The shear strain value of soil was lower for the rectangular tunnel case than that for the circular tunnel case. The rectangular tunnels required lesser trapdoor displacement than that of the circular tunnel to obtain the minimum soil arching ratio. The minimum and ultimate soil arching ratios increased as the burial depth ratio increased for both the tunnel shapes. The maximum stress ratio of the tunnel crown was consistently larger for the circular case than for the rectangular case. [ABSTRACT FROM AUTHOR]