The frost heave force (FHF) is one of the most important reason of inducing freezing damages of tunnel in seasonal frozen regions. Analyzing the change law of FHF is helpful to design for avoiding freezing damages in the tunnel lining. Field measurement is an approved method used in mechanical analysis of tunnel lining, however, it is difficult to measure the FHF directly, which is changed coupled with the original surrounding rock pressure (OSRP). In this paper, in order to clarifying the change law of the FHF, a new measuring method was presented. The best advantage of this method is that the FHF could be separated from the OSRP by measuring the surrounding rock temperature and the lining pressure at the same time. A lot of field measurement work about the FHF was conducted based on Jichoushan tunnel and the change law of the FHF was analyzed using the presented method. The results can provide preference for the antifreeze design of tunnel in seasonal cold regions.

The graphene modified asphalt used in this study was prepared based on a highway project in Gansu Province. In this paper, the high temperature rutting resistance, low temperature cracking resistance, and water stability of SMA-13 asphalt mixture with asphalt (AH-70), SBS modified asphalt and graphene rubber composite modified asphalt were tested and analyzed comparatively by the rutting test, Schellenberg binder drainage test, Cantabro test, freeze-thaw splitting test, and beam bending test. The results showed that the graphene modifier improved the asphalt’s ductility and softening point significantly, and 0.4g graphene content was the threshold and its corresponding mixture performance index. In the other tests under the same conditions, the high temperature and water stability of SMA-13 mixtures of graphene rubber modified asphalt were the best, followed by SBS modified asphalt mixture, and matrix asphalt mixture. Compared with wood fiber, graphene modifier had no significant effect on SMA-13 mixtures’ low temperature performance. The use of graphene modifiers can enhance the adhesion between asphalt and aggregate and its asphalt has good consistency and viscosity. When compared with matrix asphalt and SBS modified SMA-13 mixtures, the water and high temperature stability of graphene modified asphalt mixture is better.

In order to compare the effects of different anti stripping agents on the rheological properties of asphalt at high and low temperatures, four typical anti stripping agents, amine PA-1, non amine XT-2, hydrated lime, and cement, were selected. The complex modulus (G*), phase angle (δ), rutting factor (G*/sinδ), creep stiffness (S), and creep rate (m) were measured using the dynamic shear rheometer (DSR) and the bending beam rheometer (BBR). The microscopic mechanism was analyzed using fourier transform infrared spectroscopy (FTIR) and fluorescence microscopy (FM). The results showed that lime and cement significantly improved the high temperature performance of asphalt, with an average increase of 1.4 and 0.8 times in G */sinδ. However, PA and XT reduced the high temperature performance, with an average decrease of 19% and 11% in G */sinδ. PA and XT have little effect on the low temperature performance of asphalt, but lime and cement will reduce the low temperature performance, with an average increase of 64% and 49% in S. The results of FTIR and FM indicate that lime and cement undergo chemical reactions with asphalt, while PA and XT do not, but PA and XT can promote the swelling of modifiers in asphalt.

Mineral oil-based asphalt recycling agents pose environmental concerns, prompting the search for sustainable alternatives. To this end, a bio-recycling agent (BRA) based on waste vegetable oil (WVO) was initially designed for the utilization of recycled asphalt pavement (RAP) through the orthogonal test, and then its physical-chemical and permeating properties were analyzed by a series of tests. Next, the bio-recycled asphalt binder was prepared and its several pavement behaviors were measured via adhesion, rheology and fatigue experiments, thus its recycling efficiency was validated. Ultimately, the microscopic mechanism of bio-recycled asphalt was revealed with differential scanning calorimetry (DSC) and atomic force microscope (AFM) tests. Research results showed that the composition of BRA was determined as base oil components: permeation components: polymer components: functional components = 120: 2: 13: 2.4. Compared to two commercial recycling agents (LBS and HRA), BRA possessed better recycling effect at the same dosage, which obviously restored the adhesion, high- and low-temperature rheological properties and fatigue resistance of aged asphalt, and the BRA increased fatigue life of aged matrix asphalt binder by about 60% compared to LBS at 9% dosage. Moreover, the recycled asphalt with suitable BRA dosage can adapt to a wider range of traffic grades than original asphalt, and for aged matrix and SBS-modified asphalt binder, it was recommended that the reasonable dosage of BRA was 7%−9% and 3%−5%, respectively. The samples recycled by three recycling agents all exhibited favorable thermal stability, and which was basically the same as or higher than that of the original asphalt. Besides, after incorporating the BRA, the number and size of bee-structures in aged asphalt decreased, while the roughness of asphalt surface slightly descended. Meanwhile, compared to two-commercial recycling agents, BRA had a significant improvement on the micro adhesion of aged asphalt, and behaved a better recycling effect on the aged asphalt.

Based on the Guogaibu tunnel in weathered andesite strata, the characteristics, failure mechanisms, and treatments were investigated. Firstly, the on-site monitoring findings indicated large deformation in the tunnel vault accompanied by the local falling blocks, ultimately resulting in a collapse. Then, laboratory tests were conducted to investigate the failure mechanism. It indicated that the mineral mass of the rock gradually dissolved and microcracks gradually expanded, which was prompted by the combined effects of weathering and groundwater erosion, resulting in a decrease in the strength of andesite, especially in shear strength. Tree factors attributed to collapse include weathering effects, groundwater, and insufficient support. Based on the results, treatment measures such as tunnel circumferential grouting and advanced support were implemented to enhance the overall stability of the tunnel. Finally, on-site monitoring was carried out to investigate the effectiveness of treatments. It revealed that the treatment measures were effective for the stability of the surroundings. The failure analysis method and the implementation of treatment measures can provide guidance for the prevention and control of tunneling in weathered andesite tunnels.