Abstract
Frost heaving and boiling are the most common road disorders due to the special climatic conditions in a seasonal frozen area. From the perspective of controlling road disorders in seasonally frozen areas and making effective use of industrial waste residue, two kinds of subgrade modified soil—crumb rubber modified fly ash soil (CRFS) and oil shale waste residue modified fly ash soil (OSFS)—were proposed by the research group. The research results proved that the two new subgrade fillers both have excellent engineering characteristics in cold areas, such as high strength and low thermal conductivity, and both have the function of waste utilization, giving them broad application prospects. In road engineering, the instability of slopes and retaining walls and the uneven settlement of the subgrade are closely related to soil creep, which are problems that cannot be ignored in road design and use. As a new material to treat road disorders in seasonally frozen areas, more attention should be paid to the continuous deformation property of modified soil under long-term load. The study on the creep characteristics of the modified soil can provide reliable parameters for the design of the modified soil subgrade and predict the settlement of the subgrade after construction, which is of great significance to the stability of the subgrade. In this paper, an experimental study on the consolidation–creep characteristics of two kinds of subgrade modified soil in a seasonal frozen region was carried out, the relationship between modified soil deformation and time is discussed, and the effects of different moisture contents and compaction degrees on the creep characteristics of modified soil were analyzed. The test results provide parameters for the engineering design of modified soil subgrade and provide data support for the popularization and application of modified soil in seasonally frozen subgrade.
Highlights
Within the territory of China, the permafrost area accounts for 21.5% and the seasonal permafrost area accounts for 53.5% of the territory
Silty clay widely distributed in Northeast China is subject to frost heaving, which needs to be improved to meet the requirements of a subgrade filling
Silty clay was improved and the application of rubber particles and oil shale residues in road engineering was studied by our research group [8,9,10,11]
Summary
Within the territory of China, the permafrost area accounts for 21.5% and the seasonal permafrost area accounts for 53.5% of the territory. Both of the two modified soils have excellent engineering characteristics in cold areas, such as high strength and low thermal conductivity, as well as having an environmental protection function They have good application prospects in subgrade filling in seasonal frozen areas. Chen et al [14] studied the consolidation and seepage of laterally confined clay and pointed out that the secondary time effect was mainly generated by the action of shear stress They proposed a new consolidation model assuming that clay was a Maxwell material and solved the differential equation of a one-way case. Liu et al [29] analyzed the influence of the consolidation and creep characteristics of the composite soil on the stability of a dam foundation, established an improved nonlinear Nishikan model, and obtained the analytical formula of viscoplastic strain rate. Some meaningful conclusions were obtained, which can provide reliable parameters for the design of modified soil subgrade and guide practical engineering applications
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