No abstract

Wheeling induced compression and shearing forces are main stresses accounting for soil deformation and changes of hydraulic, gaseous and thermal properties. There are reports about the combined effects of compaction and subsequent shearing on soil hydraulic properties, but their consequences on soil strength properties (i.e., effective stress and shear strength) need to be further analysed. This study investigated the dynamics of soil mechanical properties as affected by pore water pressure (uw$$ {u}_{\mathrm{w}} $$) during compaction and shearing. Soil samples from an A‐horizon of Gleysols derived from glacial sediment and a Stagnic Luvisol from loess were analysed. The repacked and structured samples were compressed under static and cyclic loading and then sheared at two speeds (0.3 and 2.0 mm min−1) with three loading levels (50, 100, and 200 kPa). During each stress application, the uw$$ {u}_{\mathrm{w}} $$, chi factor (χ) and effective stress (σ′$$ {\sigma}^{\prime } $$) were measured and calculated. The shear strength (τ$$ \tau $$), angle of internal friction (φ$$ \varphi $$) and cohesion (c$$ c $$), were determined and fitted by the Mohr–Coulomb failure criterion. The results showed that compaction and shearing increased uw$$ {u}_{\mathrm{w}} $$ and χ in all homogenized soils while on structured soils this phenomenon only occurred when the applied loading stress exceeded the soil precompression stress. The increased uw$$ {u}_{\mathrm{w}} $$ resulted in soil hydraulic and mechanical stresses, which ultimately reduced the σ′$$ {\sigma}^{\prime } $$, especially at −6 kPa initial matric potential. Soils with finer texture, higher loading stresses and faster shear speed normally exhibited more reduced σ′$$ {\sigma}^{\prime } $$ values. The structured soil had higher τ$$ \tau $$ values with higher φ$$ \varphi $$ and c$$ c $$ compared to the homogenized soils. The changes of uw$$ {u}_{\mathrm{w}} $$ at high loading stress (i.e., 200 kPa) may overlap the normal pattern of the Mohr–Coulomb failure line that results from the theoretical Mohr envelope. Thus, to minimize the destruction of soil structure and stability induced by wheeling, it is important to consider field water content, traffic loading and wheeling speed.

Different types of distresses affect cement concrete pavement at different degrees. The determination of dominant distresses of the pavement preventive maintenance (PM) and its judgement standard can provide corresponding basis for PM decision. In this paper, 22 military airports in Northeast China, such as Heilongjiang Province, Jilin Province, and Liaoning Province, were selected to collect the data of pavement distresses. Based on the structural equation model (SEM), the structural relationship between the influencing factors of each distress and the pavement damage was established, and the goodness-of-fit of the model was tested. In addition, through path analysis, the influence degree of five kinds of latent variables such as joint distress, surface distress, vertical distress, repair distress, and fracture distress on pavement damage was obtained. Four distresses, such as corner peeling, surface peeling, surface crack, and interplate slip, were identified as the dominant distresses of PM of cement concrete pavement. On this basis, a binary classification model of confusion matrix was constructed. The basic evaluation index, receiver operating characteristic (ROC) curve, and Kolmogorov–Smirnov (KS) curve were used to comprehensively determine the judgement standard of the dominant distresses of pavement PM from multiple evaluation angles (corner peeling rate ≤ 35%, surface peeling rate ≤ 30%, surface crack rate ≤ 8%, and interplate slip rate ≤ 0.5%). The judgement standard can be combined with the corresponding prediction model to determine the optimal timing of PM of cement concrete pavement and provide pavement maintenance managers with the support of decision-making.