The ground penetrating radar (GPR) surveys the overburden of underground pipe by interpreting the image, using the reflection from underground pipe and irradiating the electromagnetic wave from surface. In order to improve the image interpretation, the experiment was conducted with the inner diameter of 50 mm and 100 mm of the underground pipe by installing the steel plate, the vinyl chloride plate, and the aluminum tape on the underground pipe, respectively. As the result, it was found that even if the width of the steel plate was 50 mm, it was effective in improving image interpretation. It was found that the difference in the material rather than the shape can be expected to improve the image interpretation. It was found that the aluminum tape can be expected to improve image interpretation as well as the steel plate. On the verification of the measurement accuracy of the over-burden, it was quantitatively found that the measurement accuracy improves when the pipe diameter is large.

 The technical standard for pavement inspection in Japan attaches importance to structural soundness of subbase layer and below. The authors have built a new way to evaluate structural soundness without traffic restrictions. This evalutation way uses crack shape, rut shape, and machine learning method (convolutional neural network:CNN). Deflection D₀ was estimated using the crack diagram, cross-sectional profile and asphalt layer thickness. This evaluation way estimated the deflection D₀ with higher accuracy than the conventional method using cracking ratio and rut depth.

 In this study, in order to apply the vehicle weight investigation results conducted by the Ministry of Land, Infrastructure, Transport and Tourism to the concrete pavement slab thickness design, the temperature measurement results of the concrete slab measured at 9-locations in Japan were analyzed to determine the time zone when the thermal stress is positive or negative, and extract the wheel load group passing at that time zone. And the effects of these results on the concrete slab fatigue damage calculation were investigated. As a result, it was found that the data of the wheel load and its action frequency collected every 12 hours in the vehicle weight investigation correspond to the time zone when the thermal stress is positive or negative, and can be used directly for the concrete slab thickness design. On the other hand, it was found that the fatigue damage level of the concrete slab when using the track traffic per day was estimated excessively according to the current design method.

 It has been reported that a dowel bar (rebar) breaks in a transverse joint of concrete pavement, where a thinning of the rebar due to corrosion and a cavity of the roadbed directly below the transverse joint due to the erosion are confirmed. Therefore, FEM analysis was performed by modeling that took the state of a thinning of the rebar and a cavity of the roadbed into consideration, then the effect on the dowel bar was verified. As a result, it was confirmed that the bending stress acting on the dowel bar increases about 18 times as much as the sound state without rebar thinning nor cavity, when rebar thinning and cavity occur in combination and progress to a certain scale. Therefore, we propose to protect the transverse joint by using a material with excellent corrosion resistance for the dowel bars and by providing an asphalt intermediate course that does not easily cause erosion below the transverse joints.

 There are many routes that were originally paved with ordinary concrete pavement, but were overlaid with asphalt pavement for some reason, mainly in routes built during the high growth period. In the case of such pavement structures, surface cracks can be determine the damage status by road surface investigation, but the joints of the concrete slabs covered with asphalt mixture cannot be investigated directly. In addition, it is often the case that the entire route has the same pavement structure, and therefore, an efficient investigation is required to cover a wide area of repair work. In this paper, in order to evaluate the soundness of the joints between asphalt mixture covered concrete slabs we describe the content of the method of efficiently investigating the load transfer rate which is one of the items to evaluate the joints.

 In this study, test sections of concrete pavement were constructed on the circular accelerated pavement testing (APT) facility and subjected to 1.2 million of 49kN equivalent standard wheel loads. The test pavement has sections with and without steel mesh in concrete slab and asphalt interlayer under the slab to investigate the effect of these devices. During the loading, FWD tests were conducted periodically and the sturactural changes were evaluated with FWD backanalysis, which considered the degradation process with 3DFEM models. The analysis revealed that interior parts of the slabs did not significantly degrade, while transverse cracks exibited severe degradation. Also, it was estimated that no void formed at the transverse joint, except for two joints on the asphalt interlayer.

 If the base course surface becomes uneven due to freezing of the subgrade, gaps occur between the concrete pavement and the base course. And the life of the pavement is reduced. Therefore, in the design of concrete pavement in snowy cold regions, it is necessary to evaluate the freezing depth appropriately and reflect it in the measures against freezing. In this study, the freezing depth of concrete pavement was measured in situ. Then, the theoretical depth of frost penetration by an existing design method in Japan, and the measured values were compared. Furthermore, as a new method, we investigated a method for estimating the freezing depth using heat balance analysis and heat conduction analysis that consider the albedo of the pavement surface. As a result, a maximum difference of 200 mm or more was found between the theoretical depth of frost penetration by the existing design method and the measured value. Then, the problems of the existing design method were shown. In addition, with the new method, the freezing depth that was almost in agreement with the measured value was obtained. It is considered believe that this new method can contribute to the improvement of the accuracy of the subgrade design of concrete pavement in cold snow regions.

 The cast in place ultra-high-performance fiber reinforced concrete (herein after, UHPFRC) basically does not contain the coarse aggregates so that behaves high fluidity immediately after mixing.

 In order to apply the cast in place type UHPFRC to reinforcing concrete bridge deck with a thin UHPFRC overlay, it is necessary to examine not only the composition of UHPFRC itself, but also the construction method in detail such as surface treatment to ensure bonding between the concrete deck and the UHPFRC layer, the specifications of the construction machine, and the curing method. In this study, the suitable composition of UHPFRC for the overlay method was found from the laboratory test results. The UHPFRC was placed with a 40mm thick layer on the cement concrete slab to simulate an overlay on concrete bridge deck and evaluate the workability on the site and the adhesion of the UHPFRC layer with the underneath concrete slab. The results indicated that a good adhesion performance could be secured with the suitable composition of UHPFRC and the wet or adhesive surface treatment of the concrete slab.

 It was reported that the fuel efficiency of heavy-duty vehicles was reduced by driving on concrete pavement compared of asphalt pavement because the rolling resistance of concrete pavement is smaller than asphalt pavement, and the reduction of CO₂ emission by improvement of the fuel efficiency was expected. CO₂ emission of concrete pavement considering the effect of the fuel efficiency reduction on N7 traffic was calculated and compared with asphalt pavement. As a result, the amount of CO₂ emission of concrete pavement only construction was bigger than that of asphalt pavement since the effect of cement was big. However, the amount of CO₂ emission of concrete pavement was smaller than asphalt pavement by considering fuel efficiency reduction of heavy-duty vehicles as contribution to environment, which contributed to decrease CO₂ emission significantly. Besides, in the case of heavy traffic of heavy-duty vehicles comparatively on N7 traffic, amount of CO₂ emission of concrete pavement is smaller than that of asphalt pavement.

 Hokkaido, a snowy cold region in Japan, has increasingly adopted porous asphalt roads since 2000. However, durability issues emerged shortly after their adoption, including localized damage and, more recently, potholes caused by melting snow. In this research, we first surveyed damage to porous asphalt on national highways in Hokkaido. The survey results indicated that porous asphalt may require repair within 10 years of public use, depending on environmental and traffic conditions associated with snowy cold regions. We also conducted a life cycle cost analysis to assess the benefits of using high-performance SMA(stone matrix asphalt), which has been used increasingly since 2017 as an alternative to porous asphalt. As a result, we estimated that the life cycle cost of using the high-performance SMA—assuming that it is adequately durable—is lower than that of using porous asphalt despite the higher initial cost of the high-performance SMA. These results indicate that using high-performance SMA on national highways would be beneficial in Hokkaido.

 Multifunctions type drainage pavement has a drainage function equivalent to drainage pavement near the surface in the same surface layer, and the lower part has a contexture of the hybrid pavement having waterproofing performance equivalent to SMA. Furthermore, this pavement characterized by this pavement forming a longitudinal groove in the pavement surface at intervals of 4 cm, and since this longitudinal groove has an effect which improves skid resistance, it can control the slide in the curve part of pavement. It is proved by the curve of the national road No. 25 named “Meihan Kokudo” from these things that this pavement can reduce a slip accident. This report evaluates quantitatively the stability at the time of sharply braking of vehicles especially about the effect which controls the slip of this pavement.

 Areinforcement material inserted asphalt mixture layers has some unclear points, such as the optimum physical properties and the mechanism of tensile strain reduction on the lower surface of the layer. The present study evaluated fundamental mechanical properties and strain reduction effect of the basalt fiber geogrid reinforcement for asphalt mixture layers. The basalt fiber has advantage with regard to material recycling. The following findings were obtained. The tensile resistance and shear resistance between the asphalt mixture layers decrease when aperture size and hardness of the grid is inappropriate. The tensile strength of the grid is not the dominant factor for the strain reduction effect, but the effect of restraining the aggregate particles is a major factor.

 We conducted laboratory and field experiments on dense-graded asphalt concrete and porous asphalt concrete in order to clarify the decrease in road friction coefficient μ caused by calcium chloride solution sprayed as an antifreezing agent. In the laboratory experiment, the skid resistance of road specimens sprayed with calcium chloride solution and that of road specimens sprinkled with water after the calcium chloride precipitated were measured. The values of μ immediately after the application of calcium chloride solution, even a high-concentration solution, were found to be at least 0.4, which is not much different from the values for the wet road surface. When calcium chloride precipitated on the road surface, the values of μ for dense-graded asphalt concrete and porous asphalt concrete were about 0.2 lower than those for the wet road surface. Furthermore, field experiments showed that the precipitation of calcium chloride and decreases in μ associated with that precipitation could occur on actual roads.

 At the Pavement Driving Laboratory of the PWRI, damage caused by slippage was considered to be interlayer slip. Therefore, the cause of inter-slip was investigated. For the investigation, a tensile adhesion test, a shear test, and a visual inspection of the cut surface were performed in order to investigate the adhesion state of the surface base layer. As a result, the cause of the inter-slip was peeling due to water entering between the surface layer and the base layer, and the fact that the tack coat was not sprinkled between the surface and base layers resulted in poor adhesion and early damage. It seems to be the cause.

 In recent years, interlayer debonding in asphalt mixtures has been observed in asphalt pavements with early deterioration, and its countermeasures are required. However, it is not clear how interlayer debonding affects pavement deterioration. In this study, we have calculated the stresses inside the pavement by multi-layer elastic analysis in the case of interlayer debonding, and have shown that damage can occur that is not taken into account in conventional pavement design. We have also focused on the deflection of FWD, which is used in many pavement investigations as a non-destructive method to diagnose the pavement structure, and have shown the change in the amount of deflection and the error in the inverse analysis caused by the conventional method in the case of interlayer debonding. Furthermore, we have shown that this error can be corrected by taking into account the interlayer debonding, and have verified the validity with FWD data obtained on the actual road.

 We have developed a pavement inspection system by using car-mounted camera and U-net model which is one of the deep learning. First, the cracks on this image were sketched by hand and the teacher data for model learning was constructed. By applying the model to the road surface image, cracks can be detected with high accuracy and speed. Next, in order to verify the accuracy of the crack evaluation using this system, we used the correct value data from the road surface property measurement vehicle. As a result of analysis from a total of 500 blocks of sample data, it was shown that the detection rate (Level II+) was rank A (80-100%), the detection rate (Level III), the hit rate (Level II+), and the hit rate (Level III) were rank B (60-80%) which proved to have sufficient inspection accuracy.

 In Japan, local government patrols their roads to maintain effectively and to collect the road condition. However, it is difficult to operate and maintain the road continuously by a lack of engineering staff and progression of road aging and deterioration. It is necessary to find the damage points efficiently. Therefore, in this research, to improve the efficiency of road patrols by local governments, we installed acceleration, global navigation satellite system (GNSS), and camera sensor devices on home delivery company vehicles that regularly use targeted roads. We devised technologies for efficiently collecting road data from these sensors and for identifying road damage sites by analyzing these data. In future studies, we plan to improve efficiency by using system for automatic extraction of road damage images and location information from acceleration data.

 In order to effectively maintain and manage the municipal roads, it is highly required to develop the practical road survey technology. The authors are conducting joint research with a British road management company aiming at the introduction of their cutting-edge road diagnosis technology to Japan. In this paper, the feasibility study of their method for the Japanese municipal road is shown. Image data of more than 60% of roads and surrounding road assets in the Yokosuka city have been obtained. The adaptability to the situation in Japan and the distinctive features of their scheme are demonstrated by comparing the results by our proposed method and conventional road survey using the survey vehicle.

 This study shows the result of constructed and verified the pavement crack prediction curve for representative points considering utility of the pavement crack prediction curve at the management site which was indicated in the previous research titled Construction and verification of pavement crack prediction curve concerning representative parts by region and condition.¹⁾ A number of studies has addressed probabilistic crack prediction predictions to support with the uncertainty crack prediction process. However, there are not many research results verified by the actual measurement results for the analyzed crack prediction prediction. In this study, considering the utility of the pavement crack prediction curve at the management site, we constructed the pavement crack prediction curve using the road surface property measurement results extracted the representative points for each route in each national road office within the jurisdiction of the Kanto Regional Development Bureau. In the verification, we compared with the previous research and created a tool that can be used at the management site.

 In road maintenance, it is necessary to construct an environment that manages 3D data and maintenance information for its effectivity and efficiency. Using 3D data will thus improve the efficiency of operations and maintenance. The primary objective of this research is to support pavement maintenance work using 3D data by constructing point cloud data of terrestrial laser scanning (TLS). This research evaluated the accuracy of the usage of point cloud data by TLS for pavement maintenance. This method can be used to check the surface irregularities on pavement that can be easily and quickly confirmed by management. The 3D data could be used to develop a pavement maintenance management system that accumulates data and refers to the inspection results and repair information. The system can link inspection results and recondition information with the point cloud data for display, storage, and reference, facilitating the management of road cracks and areas for repair. The prototype system was developed using Skyline Terra Explorer Pro. It was visualized constructed 3D data on temporal sequence.

 An improvement in operational effort of 3D measurement devices for ICT Paving Works is required because the measurement accuracy depends on the device used and the computer program for analyses, and the application of point cloud data is limited to construction quality control. This study proposes the facilitation of the data treatment of 3D point cloud data measured by a Terrestrial Laser Scanner (TLS) and an Unmanned Aerial Vehicle (UAV) which are equipped with a high-performance Global Navigation Satellite System (GNSS) with two navigation antennas. For the purpose of this study, road surface profiles of which measurement requires millimeter accuracy are acquired with the GNSS mounted 3D measuring devices. As a result, the proposed method allows accurate and efficient 3D data acquisition with setting the device coordinate and direction angle by optimizing the offset of two GNSS antennas. The findings of this study contribute to the efficiency improvement of operating 3D measurement devices by reducing some operational processes such as the target identification with achieving the same accuracy of conventional method.

 Heat blocking pavement can reduce road surface temperature compared with normal asphalt pavement. However, it has been confirmed that the heat insulating material applied in order to achieve this road surface temperature reduction effect is peeled off due to aging. In the previous document, however, it is difficult to calculate the image of the heat insulating material after manually setting the count and visual level. However, it is possible to calculate the rate of peeling by using the road surface image taken by the road surface property measuring vehicle. As a result, it has been possible to calculate the rate of peeling in the local heat insulating paving quantity is possible to calculate the rate of peeling.

 Since Japan is promoting cycle tourism nationwide, improvement of the bicycle running environment is required. However, the evaluation method of the road surface roughness that greatly affects the bicycle running environment is not established yet. By carrying out an experience evaluation experiment using a vibration table, the relationship with the ride quality when data with characteristics different from the road surface profile used in the previous research was used was grasped. Moreover, the road surface management method was examined using the constructed evaluation index. As a result, it was revealed that the constructed evaluation index can reflect the ride quality of the bicycle even when the data of the vibration table is applied. Furthermore, based on the existing research, we calculated the reference value for road surface management and proposed a reference value for judging good and bad road surfaces.

 In this study, rolling resistance was subdivided and analyzed to clarify the effect of road profile on rolling resistance. In the study, the rolling resistance coefficient was calculated for each 1-m section, and the relationship between the resistance and the traveling speed and the road surface profile was examined. As a result, it was considered that drag generated when the tire passed on a road surface having a certain characteristic, as well as the air resistance, was one of the factors. For this verification, we attempted to detect the characteristic shape that the rolling resistance increases by the method using the lifting scheme of wavelet analysis. As a result, the detection points and the points where the rolling resistance increased were almost the same position. As a result of the above verification, it was confirmed that the characteristic road surface shape affects rolling resistance and is one of the factors that influence speed dependence.

 In this investigation, the factors that can influence the charge characteristics of asphaltene were verified. As a result, it was shown that the deteriorated asphaltene was negatively charged regardless of the deterioration factor, the composition of the rejuvenators, and the repeated-recycle asphalt. Also the absolute value of the zeta potential was suggested to vary depending on the degree of oxidative deterioration. In addition, the charge property of the asphaltene-resin mixed suspension was affected by deteriorated asphaltene or deteriorated resin. However, it seems that aggregation occurred at low pH if asphaltene or resin deteriorated. Furthermore, it was suggested that, in the non-aqueous solvent the electrostatic repulsive energy contributed less to the interaction between asphaltene particles.

 Embrittlement of asphalt binder, as an adhesive, induces asphalt pavement surface cracking with traffic load and temperature change. Asphalt degradation is mainly the result of oxidative reaction, and may be caused by ultra violet rays effect in addition to high temperature exposure during construction and summertime heat. Although there are previous findings focusing on laboratory binder testing and samples investigation from road pavement, only a few researches have reported on the evaluation of UV effect using asphalt mixtures. This research confirmed that asphalt deterioration at very surface is the most severe and the rate of degradation can be estimated by accumulative amount of UV light, by the strong UV light radiation tests on asphalt mixtures. Asphalt degradation is depending on the quality of surface mixture, and compaction rate particularly has high impact on the aging level. It is also verified that a pavement surface treatment such as slurry sealing can inhibit asphalt degradation by the effect of an UV light barrier.

 In order to extend the life of asphalt pavement, it is important and the simplest way to increase the strength of interlayer bonding. However, there is no appropriate method to evaluate this property. In this consideration, we developed a half-section wheel tracking test, simulating a running vehicle at the cold joint, to measure the material used for. Specimens under traffic loads was used for both shearing and permeability tests, then, the adhesiveness and water stopping property were evaluated successfully. Regarding tack coat used for the interlayers, tensile adhesion test is commonly used, but there remain concerns about whether the adhesive strength could be evaluated properly. Therefore, we developed new equipment and testing method that repeatedly applied water pressure between the layers of the asphalt mixture. Reproduce of interlayer de-bonding phenomena by pressurized water, obtained the bonding properties of several type of tack coat.

 In order to efficiently repair on asphalt pavements, it is necessary to properly evaluate the properties of the existing asphalt pavements. Although there are many tests that directly evaluate the properties of existing asphalt pavements, it is extremely difficult to properly evaluate thin asphalt pavements like pavements on bridges. For this reason, the authors have developed the cyclic torsional shear test and are studying methods of characterizing asphalt mixtures. In this study, we used the aging specimens and clarified the effect of different aging on the test results. And we examined aging evaluation index of asphalt mixtures.

 The repeated compressive-tensile test using core-samples taken from asphalt pavement fields is an effective method to assess the damage state of the asphalt layer. For this assessment, characteristics indexes obtained from the test need to be related with the fatigue damage state of the core-sample. The present study investigated the viscoelastic parameters derived from the test data in order to relate the fatigue damage state. The results confirmed that the fatigue damage state of the asphalt mixture could be explained by evaluation of the energy history during the repeated loading. The relationship between cumulative dissipated energy and phase angle in the energy history was useful information for the assessment.

 The Handbook of Pavement Recycling was revised in 2010. The revision includes a new mix design method for recycled asphalt mixtures, using design compression splitting coefficients. However, no design compression splitting coefficient is given for recycled asphalt with a penetration value of 80-100 (1/10 mm), which is the standard used in the Hokkaido region. For this reason, in the Hokkaido region, use of a compression splitting coefficient has not been promoted in either the design of recycled asphalt mixtures or the quality control of recycled aggregate. In this study, the compression splitting coefficients of a recycled asphalt mixture prepared by the existing mix design method using the design penetration value were measured in order to determine the design compression splitting coefficient. As a result, it was found that 0.25-0.40MPa/mm is an appropriate design compression splitting coefficient for recycled asphalt with a penetration value of 80-100 (1/10 mm).

 Recycling of asphalt pavement in Japan has been carried out for over 40 years, and recycled aggregate is considered to be recycled multiple times depending on the regions. In order to continue the permanent recycling of pavement toward the future, it is necessary to clarify the effect of the recycled aggregate ratio and the rejuvenators in consideration of repeated use. Therefore, in this study, recycled asphalt mixtures with two types of rejuvenator with different composition and recycled aggregate ratio with 4 levels were repeatedly aged and recycled, and their property changes and effects were examined by laboratory experiments. As for the composition of the additive for regeneration, attention was paid to saturated components and aromatic components. As a result, it was clarified that the properties of the new mixture remarkably changed depending on the composition of the rejuvenator and the mixing ratio of the recycled aggregate. In particular, it became clear that the crack resistance at high temperatures decreased, and the evaluation method was also examined.

 This paper presents the utilization of both forming techniques and chemical additives for warm mix - recycled asphalt (WMRA). The production of recycled asphalt mixtures in Japan is about 76% occupied although the warm mix asphalt (WMA) using forming techniques or chemical additives is only 0.3% occupied. The main reasons of few WMA production are both the less cost effectiveness compared with conventional hot mix asphalt and its quality issues. As countermeasure, the forming technique for WMA is fully expected for saving costs, however it is well-known that the mixture quality is strongly dependent on the proportion ratio of recycled aggregates. In this study, the authors investigated a WMRAutilizing both forming techniques and chemical additives. According to the testing results of laboratory test and trial production, the WMRA using high recycled aggregates proportions of 60% shows the reduction of the production temperatures of 30℃ and improve workability. The compaction characteristics of the WMRA mixtures at lower temperatures also show the good performance as same as conventional recycled asphalt using same aggregate proportion.

 Well-grained sand is generally used for the filter layer of permeable pavement, but non-woven fabrics are also used in some cases to serve as both a filter layer and a measure for preventing subgrade soil from penetrating the roadbed. According to previous research, non-woven fabric used for this purpose needs to have a unit weight of 200 g/m². However, there are issues with this related to weight and ease of cutting in the surrounding areas of the road.

 In this study, non-woven fabric with reduced unit weight was fortified with claf and subjected to damage testing using a roller compactor testing apparatus to evaluate its durability, then the level of performance required for this surface-reinforced non-woven fabric was examined based on the road surface properties in a field test at an actual construction site. Based on the durability indicated by sample damage testing and the results of the field test, a unit weight of 131 g/m² is sufficient for achieving the required performance with a surface-reinforced non-woven fabric filter layer.

 The purpose of this study is to propose a method for estimating the deformation modulus that appropriately reflects the effect of stress dependency and drainage condition on the deformation modulus of subgrade soil. A series of cyclic triaxial test combined with the bender element test (CTX-BE test) was performed on five soil materials with different physical properties (Toyoura sand, diluvial sand, decomposed granite soil, alluvial clay, loam) under drained/undrained conditions. The relationship between the shear modulus G, the deformation modulus E and the mean effective stress σ_m’ under both conditions was obtained. Furthermore, based on the report of previous study that the shear modulus G is strongly affected by the void ratio e, measured G in the CTX-BE test was corrected by the void ratio function f(e), and the G-e-σ_m’ relationship were more clearly understood. Then, the relational expression E/f(e)=Aσ_m’ⁿ peculiar to the material under different drainage conditions was investigated, and a simple formula estimating deformation modulus was proposed in which the void ratio and the mean effective stress only are given parameters.

 This study investigated the application of the cement asphalt emulsion stabilization (CAE) to pavements that experience frost heave damage in cold regions by performing test construction using the CAE. Laboratory experiments show that the CBR of the base course can be improved by 200% or more by using the CAE, and comparison with previous studies showed that frost heave can be sufficiently suppressed if CBR is improved by 150% or more. To directly investigate its frost heave suppression effect, the CAE was applied to a frost-susceptible and the results showed that the frost susceptibility was reduced by 40% or more. In situ observation also confirmed a clear frost heave suppression effect by the CAE, and the stiffness of the CAE base course very likely contributes to frost heave suppression. Furthermore, the results showed that the CAE was effective against worsening of roughness and reduction of bearing capacity, both of which are seen during the melting period.

 In order to investigate influence to cohesion c and liquefaction resistance of base course material by asphalt emulsion addition amount, undrained triaxial compression tests and cyclic triaxial tests were carried out. From the results, cohesion c was increased as increasing asphalt emulsion addition amount. Asphalt emulsion addition amount was 17%, cohesion c was reached to 12.0 kN/m², this value is the maximum in this study. On the other hand, liquefaction strength ratio defined shear stress during liquefaction after 20 loads was R_L20 =0.27 at 10% emulsion addition amount, cyclic shear strength ratio didn't change even if the asphalt emulsion addition amount was some increased further. However, the liquefaction resistance when loaded with the small shear stress increases with increasing asphalt emulsion addition amount.

 In order to reduce the cost of track maintenance, ballastress track for existing was developed, in which the ballast voids were filled with cement grout. However, some constructed ballastress tracks require repair within a few years after operation on the soft roadbed. Therefore, in this study, we developed a construction method that can improve the roadbed simultaneously with the construction of the ballastress track, when the ballastress track installed on a soft roadbed. We evaluated the deformation characteristics of the ballastress track with improved roadbed by full scale loading tests. It was also found that the amount of plastic settlement of ballastress track could be evaluated by repeated triaxial compression test of subgrade materials. Furthermore, we confirmed the effect of reducing the stress generated in the existing ballastless track by applying the roadbed improvement.

 In the ballasted track laid on the sandbar area, the fine particles of the ballast and the sand flying from the outside deposit on the ballast layer. In addition, the mud pumping may be generated due to the decrease in drainage performance of the ballast layer. In such a section, the application of the ballastless track injected with superfine particle cement milk is considered to reduce the maintenance frequency related to ballasted track. In this study, the settlement characteristics of the ballastless track on the sand roadbed were examined by experimental and analytical methods. As the results of the cyclic loading tests of full-scale track model, cyclic triaxial tests of cylindrical specimens and finite element analysis, it was concluded that the ballastless track is likely to be applicable to the sand roadbed.