Aiming at the problem of the deformation of the roadway floor plate during the laneway during the retention period, the mechanical model of the roadway floor is established, and the deformation characteristics of the roadway floor and the change law of the bottom drum are studied and analyzed through theoretical calculation and calculus simulation, revealing the instability mechanism of the surrounding rock of the roadway under the stress disturbance environment, and when not affected by the adoption, the roadway forms a certain stress concentration area within the effective range of support. During mining, under the comprehensive action of the original peripheral stress field and the mining stress field, the cliffhanger is unstable under the comprehensive action of the original peripheral stress field and the mining stress field, and the extrusion and stretching effect of the unflapped part of the rock layer above the goaf section of the coal seam is set up along the air, resulting in violent deformation such as the bottom drum, and the rotational sinking of this part of the unflinted rock layer further aggravates the transfer of the overburden load to the surrounding rock of the lane, so that the surrounding rock along the empty lane is subjected to a large additional stress, and the mining stress field plays a leading role, and the mining stress “far field” is the compound stress field, of which the tensile stress is the leading destructive factor. The deformation of the surrounding rock is mainly based on the bottom, and the horizontal stress on the bottom plate along the empty lane is mainly generated by the horizontal strain that occurs after the lower rock layer of the filling body and the coal gang is subjected to the supporting pressure transmitted by the top plate. With the mining of the working surface, the roof of the goaf area is broken and collapsed to form the characteristics of “vertical three belts,” which is affected by the “large support” of the coal body of the working surface and the “small support” of the surrounding rock along the empty roadway, and the pressure relief of the cut roof can make the roof plate along the empty lane change from the “long arm beam” structure when the roof is not cut into the “short arm beam” structure, blocking the lateral stress of the goaf area to the roof plate of the alley and significantly reducing the degree of stress superposition of the roof plate of the alley. The technical means of blasting cutting roof active pressure relief and protective lane are used to block the transmission of lateral support pressure, the roof slate layer is precracked in advance, the sinking of the rock layer is accelerated, the disturbance time is reduced, the vertical stress of the rock layer and the rock layer above it along the empty roadway is reduced, the vertical stress concentration of the roadway is reduced, the stress concentration coefficient is reduced, the degree of damage of the surrounding rock after the top is weakened, the damage range is reduced, and the technical problem of large deformation prevention and control along the bottom drum of the empty alley can be solved. Constructing the mechanical structure model of the top plate of the cut top pressure relief and the uncut top pressure relief along the empty lane, the stress change characteristics of the active protective rock surrounding rock along the hollow top of the cut top pressure relief were calculated, and after the technical scheme of the blasting cut top active pressure relief and protection lane was adopted, the deformation along the empty roadway was significantly weakened, the stability of the surrounding rock of the roadway after the blasting of the cut roof was significantly improved, the maintenance state along the section of the empty roadway was good, and the cross-sectional convergence rate was reduced by 37.3% compared with the original section. Cutting the roof active pressure relief and protective lane can effectively improve the stability of the surrounding rock.

Surface segregation in asphalt mixture caused by the homogeneity of aggregates seriously influences the service life and road performance of asphalt pavements. However, existing segregation detection procedures are cumbersome and the detecting results are heavily influenced by the moisture content of the surface asphalt mixture. Therefore, this paper innovatively proposes two-dimensional (2D) entropy of the chunking image in calculating uniformity complexity (U) to evaluate surface segregation of bituminous mixtures with digital image processing (DIP). Before image chunking, Otsu algorithm and Canny edge detection are properly combined to obtain a more accurate aggregate distribution image. Furthermore, the feasibility of this detecting method is verified through a simulation experiment, a grading comparison experiment, and a noise interference experiment. These experimental results demonstrated that this study presents an efficient approach for the segregation detection of asphalt mixture with high accuracy.

In asphalt concrete pavement layered system, interlayer bonding condition has significant effect on its behavior and performance. Bond condition between asphalt layer and semi-rigid base layer is more severe than others because of the different mechanical response under environmental and traffic loading. In this study, continuous construction method (CCM) is proposed to improve the bonding condition by increasing layers interlock depth. As a new construction method, the laboratory testing and field testing are conducted to understand the mechanism of bonding improvement. Quality control methods during the procedures of CCM are proposed. Optimal initial compaction degree of the base layer and paving time interval between base layer and asphalt layer are suggested for better bonding condition. According to the results of field crack survey and deflection testing, CCM can reduce transverse crack number and deflection level with better bonding condition between asphalt layer and semi-rigid base.

A continuous construction method (CCM) was proposed to decrease the reflective cracking generated from the cement-treated macadam base by reducing the shrinkage of base materials and improving the bond strength at the interface between the base layer and surface layer. Traditional 3-7 days of curing period of cement-treated macadam base was eliminated by CCM and the asphalt mixture can be paved immediately after the construction of cement-treated macadam base. An anti-cracking agent was developed and added into the cement-treated base materials to prolong the hydration process and improve the shrinkage performance of base materials. The influences of anti-cracking agent on the properties of cement-treated materials were analysed using laboratory tests. The generation of micro-expansion ettringite from cement system was investigated from the microscopic perspective using the scanning electronic microscope test. Test roads were constructed and contrasted to demonstrate the feasibility of this approach and showed a superior anti-cracking performance.

Based on the comprehensive effects of phosphogypsum on properties of cement, the phosphogypsum was used to develop an anti-cracking agent with citric acid as an auxiliary set retarder. This anti-cracking agent was added into the cement-stabilized base materials to apply the Continuous Construction Method (CCM). On one hand, an anti-cracking agent prolongs the initial setting time of the base materials to 8-10 hours to guarantee that the asphalt mixture is being paved and compacted before the cement-stabilized materials hardened. On the other hand, micro-expansion substances generated from the pozzolanic reaction between the cement-treated materials and an anti-cracking agent contribute to reducing the porosity of the cement-treated base and the contraction space for drying shrinkage and temperature shrinkage. Strength, setting time, and dry shrinkage were used as the evaluation indicators in laboratory tests to determine the suitable dosage of the addition agent. The anti-cracking mechanism was analyzed from the microscopic perspective by the scanning electronic microscope.

The cement-treated base(CTB) has been used successfully to address ever-increasing traffic volume and at locations where subgrade quality is poor, however, one of the main distresses for asphalt pavement with CTB is reflective cracking. An innovative construction methods[Continuous Construction Method(CCM)] was proposed in this paper to mitigate the premature cracking originated from the CTB. The CCM differs from the traditional construction method in the construction process. Traditionally, the CTB need to be cured for 3to 7days after paving to secure strength, this procedure was canceled in CCM and the asphalt mixture was supposed to be paved immediately after the construction of CTB. Anti-cracking agent was developed and added into the cement stabilized base materials to prolong the hydration process and initial setting time of the base materials, thus providing sufficient time for paving the asphalt concrete layer and guaranteeing the asphalt mixture being paved and compacted before the cement stabilized materials hardened. In addition, micro-expansion materials generated from the pozzolanic reaction between cement-treated materials and anti-cracking agent could contribute to reducing the porosity of CTB and the contraction space for drying shrinkage and temperature shrinkage. In this paper, the influences of anti-cracking agent on setting time of cement paste, basic mechanical property and shrinkage property of cementtreated materials were analyzed, and the generation of ettringite from cement system was investigated from the microscopic perspective by the scanning electronic microscope (SEM). The test results indicated that the cement treated materials with anticracking agent have good micro-expansion and densification performance, which significantly reduces the shrinkage caused by the temperature and humidity change, improves the pavement performance of CTB and prolongs the roadway service life. Additionally, test roads were constructed and contrasted to verify the anti-cracking effectiveness of CCM. Pavement performance was monitored for 4 to 5 years after construction. During the evaluation period, both laboratory and field tests were conducted to obtain the strength, bonding condition and cracking rate data. The results showed a superior compositive anti-cracking performance of CCM. Bond strength and shear strength Jia Li, Jianmin Zi, Tao Hu School of Civil Engineering and Mechanics Huazhong University of Science & Technology 1037 Luoyu Road, Wuhan, China Doraemon2012@hust.edu.cn