In highway pavements, cement stabilized subbase is employed as the subbase course for long-term durability, except in cold regions. An excavation survey of a rutted section that had been subjected to traffic loads for several decades showed that the upper surface of the subbase course had lost durability due to permanent deformation, which was thought to be caused by consolidation settlement, and cement components that had not set due to neutralization. Test results indicated that the microstructure of the cement stabilized subbase brought about by hydration-related substanc-es had affected the long-term durability of the subbase course, and that not only water and carbon dioxide, but also anti-freezing agents, were responsible for the deterioration. In this paper, the deformation mechanism is inferred and measures to improve the durability of the cement stabilized subbase are proposed based on the above.

 To manage and operate the pavement infrastructure in a planned and efficient manner, it is essential to accurately assess the current condition of the pavement, predict future deterioration and carry out maintenance and repairs at the right time and in the right place. To achieve this, it is crucially important to understand how pavement damage and degradation occur and how they develop. This study focused on the interaction of asphalt aggregate interfaces and verified and discussed how damage and degradation occur and the mechanisms of their developments through physical property measurements by nondestructive microscopic measurements of asphalt mixture by X-ray CT using SPring-8. The results confirmed that asphalt delamination from aggregates, cohesive fracture of asphalt and direct contact point between aggregates with each other are possible damage initiation points and that there are effective methods to control asphalt delamination. Based on these findings, methods for contributing pavement damage control are proposed.

 In snowy and cold regions, freezing reaches the subgrade of the pavement during severe winter and generates cracks in the asphalt mixture layer from frost heaving. In addition, after the frozen subgrade thaws, the bearing capacity of the subgrade decreases, which may lead to the cracking and subsidence of the asphalt mixture layer. Therefore, in constructing long-life pavements in snowy and cold regions, it is important to control frost heaving. In this study, as a measure against frost heaving in existing asphalt pavements that have undergone damage as a result of insufficiently deep soil replacement, we constructed an experimental pavement using insulation that afforded shallower excavation depths than those of the method involving soil replacement. A seven-year follow-up survey found that the pavement constructed with the insulation method had the frost heave control capacity and a bearing capacity that were equivalent to those of the pavement constructed with the soil replacement method.

 In cold regions, low-temperature cracking of asphalt pavements brings rainwater intrusion, that causes deterioration from surface to base course due to repeated freezing and thawing as well as loading. In this study, we analyzed the mechanism by which low-temperature cracks occur, clarified the performance required for asphalt mixtures that prevent low-temperature cracks, and developed an evaluation method. The required performance index consists to the two aspects according to short-term performance and long-term performance. The former (short-term performance) is the tensile strain corresponding to the maximum daily temperature change measured in winter. The latter (long-term performance) is the accumulated strain when temperature stress acts for a long period of time.

 A static tensile test was used to evaluate the former, and a newly developed testing system capable of conducting three types of tests, a temperature stress test under complete restraint, a creep test, and a static tensile test, was used to evaluate the latter. The new asphalt mixture developed for anti-low-temperature cracking met the required performance

 In recent years, the importance of the issue of age-related damage and long-term durability of asphalt pavements has been increased. In order to extend the service life of asphalt pavements, the development of tack coat with long-term adhesion is being promoted because it is expected that the long-lasting interlayer adhesion of asphalt pavements will greatly extend the service life of asphalt pavements. In Japan, the adhesion of tack coat is mainly evaluated by tensile adhesion test, but sometimes it is not possible to evaluate the adhesion properly because of the internal failure of asphalt mixture especially at high tempetatare or using modified asphalt emulsion with strong bonding property. On the other hand, overseas, tack coat is evaluated by a shear test using a test fixture designed to suppress internal failure of the asphalt mixture. Therefore, the applicability of the cylindrical shear test to the evaluation of tack coat adhesion was examined in this study. The results suggest that the cylindrical shear test can suppress the internal failure of asphalt mixtures and can appropriately evaluate the adhesive properties of tack coat.

 The present study investigated effects of multiple cycles of aging and regeneration on physical properties of recycled asphalt mixtures containing four types of reclaimed asphalt pavements (RAP) with different degrees of aging. The recycled asphalt mixtures after repeated aged and regenerated had different physical properties depending on the aging degree of the RAP. More the deterioration of RAP progresses, the greater the proportion of aged asphalt that does not function effectively as a binder, and the crack resistance, water resistance, and workability decreased. Furthermore, a comparison of substandard RAP with different degrees of aged showed that the mixture properties decreased from the first regeneration on the recycled mixture using RAP with considerably advanced degradation. On the other hand, the recycled mixture using RAP with relatively less advanced degradation showed a slower decline in mixture properties, and had the same performance as the recycled mixture using RAP that satisfied the quality criteria.

 To promote the practical application and widespread adoption of alternative asphalt binders, it is essential to demonstrate their effectiveness in reducing environmental impact. However, a fair and versatile evaluation method has not yet been established. In addition, it can be assumed that adopting new materials expected to reduce environmental impact as pavement materials is challenging because their costs tend to be higher than those of conventional ones. In this study, a method for calculating the Life Cycle CO₂ emission (LCCO₂) of pavements based on ISO standards and other relevant guidelines was developed. Additionally, a method for integrating LCC (Life Cycle Cost) and LCCO₂ using a carbon tax was investigated to select pavement materials considering both economic efficiency and environmental impact reduction. Then, the LCCO₂ and the LCC/LCCO₂ integrated values were calculated for pavements using alternative asphalt binders incorporating plant-derived materials and waste plastics, and the validity and issues of the proposed method were discussed.

 Recently, electromagnetic wave density measurement devices have been used for density control at construction sites. However, as with the core sampling method, the measurement is made at a point, making it difficult to control the density of the entire construction area (areal control). Therefore, there is a need for a technology to measure density nondestructively, quickly, and continuously.

 In this study, to clarify the measurement accuracy of the newly developed mobile asphalt pavement density measuring device (RDM), the relationship between the relative permittivity of the asphalt mixture and density was obtained through laboratory tests. Next, the core density of the constructed test pavement was compared with the density measured by the RDM, and it was found that the two values were almost equal. Furthermore, when compared to the density measured by a commonly used electromagnetic wave density measurement device, the RDM was found to be extremely higher.

 In asphalt pavement construction, it is important to control the density of the asphalt mixture. However, core sampling and commonly used electromagnetic wave density measurement devices are point measurements and cannot control the density of the entire construction area (areal control). In this study, test pavements were constructed using four types of asphalt mixtures. In-situ density measurements were made using a mobile asphalt pavement density measuring device (RDM).As a result, it was clarified that the density profile measured by the RDM can be used to draw density contours, which enables areal control of in-situ density, which was not possible with the conventional method. It was shown that RDM can visualize changes in the degree of compaction during the construction process. The areal density control using RDM is a powerful method for verifying the effectiveness of compaction methods and for improving construction machinery and compaction methods.

 Evaluation of pavement deterioration is important for efficient maintenance of asphalt pavements. Cracks in the asphalt pavement surface and insufficient pavement compaction induce failure due to water and air infiltration. In order to understand the effect of pavement damage level on the degradation properties of asphalt, the air permeability of the pavement was evaluated in the continuous cross-sectional direction from the existing pavement surface at different damage levels in this study. In addition, the degradation properties of the asphalt mixture and the degradation progression in the depth direction were evaluated.

 Japan has a long history for reclaimed asphalt pavement (RAP), and the number of repeated recycling for the RAP mixtures tends to increase in the future. Therefore, this raises concerns about the poor performance of recycled asphalt mixtures, such as stripping potential of asphalt mixtures. The water-immersion wheel-tracking test (WTT) is widely used in Japan for evaluating the moisture resistance of mixtures. However, recycled mixtures tend to have higher rutting resistance than the conventional mixtures, and this may lead to good results in the water-immersion WTT. Therefore, the stripping performance of recycled asphalt mixtures cannot be evaluated correctly using the water-immersion WTT. This study used the Hamburg wheel-tracking test to evaluate the moisture susceptibility of recycled asphalt mixtures with different contents of reclaimed asphalt pavement and different numbers of repeated recycling. Three indices obtained for the Hamburg wheel-tracking test results were evaluated. The results indicated that SN is more appropriate than SIP (cycles) or SIP (cycles/mm) to evaluate the effect of the number of repeated recycling and the content of RAP on the moisture susceptibility of RAP mixtures.

 To investigate the impact of particle shape changes in fine aggregate due to grinding treatment using a classifier on the mechanical properties of Asphalt mastic, uniaxial compression, wheel tracking, and bending tests were performed on Asphalt mastic incorporating three different gradations of fine aggregate (manufactured sand), with and without grinding treatment. The results showed no significant differences in the optimum asphalt content or standard density between the treated and untreated aggregates. Additionally, the values for uniaxial compressive strength q_u, dynamic stability DS flexural strength σ, and strain ε remained largely unaffected by the grinding treatment, indicating minimal influence on the mechanical properties.

 With the increasing use of reclaimed asphalt pavements, including polymer modified bitumen, and repeated recycling of asphalt mixtures, the composition and aging state of bitumen after using has been more complex. In order to maintain preferable pavements and continue recycling, it is necessary to clarify the mechanisms of bitumen aging and recycling. This study attempted analysis using AFM-IR, which can measure both physical and chemical properties at nanoscale at the same coordinates on the sample surface, to microscopically analyze the homogeneity, compatibility, colloidal state, etc. of four mixes from bitumen and rejuvenators. The results demonstrated that the wrinkled structure like bees in the bitumen can be captured and confirmed how this structure changes due to aging and the components of the rejuvenator. We also observed the distribution of carbonyl groups, which are an indicator of aging, in the bitumen microstructure and their increase with aging by AFM-IR.

 The cracking resistance of asphalt mixtures is changing due to the use of high-flow-resistant asphalt and recycled aggregates. Therefore, a universal test method was deemed necessary to investigate quality fluctuations in plants. Thus, this study aimed to propose a general-purpose crack resistance test method using 100 mm specimens based on the SCB test. The experimental results showed that a specimen with a diameter of 100 mm could be used for evaluation, based on a comparison with a specimen with a diameter of 150 mm and a discussion of the fracture process in the SCB test. In addition, based on the experimental results for each test condition, it was shown that it is desirable to use a specimen with a diameter of 100 mm, a movable fulcrum, a notch depth of 10 mm and a storage temperature of 20 °C or less.

 The effects of cement and asphalt emulsion on the undrained shear strength of mixtures were investigated in triaxial tests. The results showed that cement contributed to an increase in the maximum axial differential stress q_max and the coefficient of deformation E₅₀, while asphalt emulsion had a significant effect on the residual strength ratio R_sr, which is the axial differential stress q_15% at 15% axial strain divided by the maximum axial differential stress q_max . For both asphalt emulsion-cement and asphalt emulsion-only mixtures, the residual strength ratio R_sr increased as the amount of asphalt emulsion added increased. Furthermore, as for the strength constants, the adhesion force c′ increased and the internal friction angle φ′ decreased with increasing amount of asphalt emulsion in the asphalt emulsion-cement mixture, while no clear change in strength constants was observed in the asphalt emulsion-only mixture.

 On the Hanshin Expressway, steel fiber reinforced concrete (SFRC) pavement is used on existing steel deck slabs as a measure against fatigue. During repairs of the surface layer pavement situated above the SFRC pavement, there is a possibility that the SFRC pavement could be partially cut by a cutting machine, which might cause fiber protrusion from the SFRC pavement. Although a waterproof layer is installed to ensure the durability of the SFRC pavement, the unevenness caused by cutting and the fiber protrusion can lead to a decrease in the waterproof performance of the waterproof layer on the SFRC pavement surface. To address this issue, this study aims to ensure waterproof performance on SFRC pavement with fiber protrusion without removing the fibers by applying a resin-based waterproof asphalt pavement that can form a water-impermeable layer integrated with the base layer. Experimental investigations confirmed that this method offers sufficient performance compared to conventional heated asphalt coating waterproofing.

 In periodic inspections of urban expressway bridge deck pavements, high-resolution line-scan images are used. The operator visually determines the presence or absence of cracks from the line-scan images. This process is time-consuming and labor-intensive. Therefore, existing research has devised a method to automatically determine the presence or absence of cracks on a segmented image basis. However, this method does not provide results that can replace the operator's work because it cannot identify the presence or absence of cracks on a pixel-by-pixel basis.

 In this study, we developed a method to automatically detect cracks in line-scan images pixel by pixel using image domain segmentation. In a demonstration experiment, cracks in dense-grained pavement and drainage pavement were detected with an F-score of approximately 0.8. Furthermore, the optimal image segmentation method for each pavement type, as well as effective image processing for crack detection were identified.

 In Hokkaido, there is concern about the reduction of riding safety and comfort on cracked road surfaces on bicycle paths. However, the most important factor that has not received enough attention is the understanding of the occurrence of pavement damage and maintenance management in bicycle paths. In this study, a network-level pavement evaluation method was developed by incorporating a crack type identification method for bicycle lanes into a simple road surface condition measurement technology and using spatial information analysis such as scenario analysis and hotspot analysis. We applied this method to the Tokapuchi 400 and found that in the scenario where repairs are carried out according to conventional management standards, the cracks in the bicycle lanes are eliminated in about 5% of the sections. It was also found that the longitudinal cracks in the pavement are continuously distributed over a distance of about 3 km in the mountainous areas and the plains.

 In road infrastructure maintenance, accurately assessing and managing pavement conditions is crucial. However, existing methods face challenges in terms of efficiency, precision, and cost, highlighting the need for high-efficiency, high-precision, and cost-effective techniques. This study proposes an advanced method for evaluating wheel ruts using a smartphone-mounted camera and image analysis. The proposed approach enhances accuracy through feature-matching-based bird’s-eye view correction and template matching to improve distortion evaluation. Additionally, it extends to 3D road surface shape estimation, including longitudinal local road conditions such as potholes and unevenness at the joint. Experimental validation confirms that the method can effectively assess various road surface features in three dimensions.

 To efficiently manage pavement maintenance, preventive maintenance approach that takes measures before damage becomes significant is required. This study proposes a method to evaluate the future damage state using the current damage state based on the crack rate and the crack progression predicted from MMS point cloud data. This method was applied to a national highway in the Tohoku region, classifying the crack rate into three diagnostic categories (I, II, III) according to the Pavement Inspection Manual, and the crack progression into two levels ("Low (L)" and "High (H)"). Combining these classifications, the pavement condition was categorized into five groups: I-L, I-H, II-L, II-H, and III. For repairs, areas with a crack rate of III were given the highest priority, followed by areas with a crack rate of II and a high crack progression (II-H). Additionally, it was revealed that there are critical areas (I-H) with a diagnostic category of I but a high crack progression.

 Expressway play an important role in the construction of arterial road networks. On the other hand, users have complained about the road surface condition, and effective maintenance of the road surface is necessary to maintain a high level of service that allows vehicles to travel at high speeds without stress. In this study, for the purpose of preventive maintenance of road surfaces, the distribution status and causes of complaints received from expressway users were analyzed based on geographical analysis after classifying the type of damage. In addition, the road surface profile analysis focusing on individual complaint points suggested that the deterioration of road surface condition (occurrence of road surface damage leading to complaints) can be confirmed by looking at the increase in the excellence level of road surface wavelength in the 4-8 m wavelength range.

 Bicycles with infant seats have become a common means of transportation for infants and drivers. Although studies on road surface evaluation considering infant seating have considered road surface roughness as a concern for passengers, but the magnitude of local road surface irregularities that causes road surface roughness is not yet clear. In this study, focusing on the steps that generate vehicle vibration, which is a risk to infants riding in infant seats of bicycles, the objective was to understand the scale of local road surface irregularities through vibration evaluation by driving tests and investigation of road surface profile analysis methods. As a result, the relationship between vibrations and step height that poses a potential risk to an infant was clarified. We used differential filter that considers the vibration characteristics of infant seats in the measured road profile in this study and demonstrated that localized pavement irregularities can be visualized.

 Until now, the BRI (Bicycle Ride Index) has been used to evaluate road surfaces on a single measurement near the outside line of the roadway on which bicycles travel. However, since bicyclists ride over a certain width of roadway, it is necessary to evaluate the road surface not only linearly but also areal-wise. In this study, we evaluated bicycle paths by BRI using point cloud data acquired by MMS (Mobile Mapping System) and calculated BRI by extracting road surface profiles from the point cloud data in order to examine the usefulness of MMS. As a result, the road surface properties in the areas with high BRI values were confirmed to be unique, and it was clarified that it is possible to evaluate bicycle paths by calculating BRI using the road surface profiles extracted from the point cloud data acquired by MMS.

 We have devised two new pavement rehabilitation methods to extend the lifespan of asphalt pavement on expressways. The two methods are to use highly durable asphalt for the binder course and the asphalt stabilized base course, and to reinforce the lower base course directly beneath the wheelpass at equal intervals. We named each of these methods “Method of reinforcing the binder course and asphalt stabilized base course” and “Method of base course rein-forced with cement piles”. Then, for the two methods, the strain was calculated using 3DFEM, and the fatigue life of the pavement was calculated from the strain. Fatigue life was determined for the method of reinforcing the binder course and asphalt stabilized base course by varying the rate of inter-fase of layers bonding between the binder course and the asphalt stabilized base course and between the asphalt stabilized base course and the subbase course. The number of fatigue failures was 5.7 times higher than that of the inservice asphalt mixture repaired with the same material, indicating that the adhesion between the base layer and asphalt stabilized base course has a significant influence on the fatigue life of asphalt pavements. The number of fatigue failures of the method of base course rein-forced with cement piles was 1.2 times higher than that of the inservice asphalt mixture repaired with the same material.

 It has become evident that water infiltration into the pavement structure, often through cracks, is a primary factor in the early deterioration of pavements. However, there are still many unknowns regarding the progression and extent of water-induced damage. In this study, a test section was constructed to simulate the conditions of water infiltration into the pavement, and full-scale loading tests were conducted to examine how the infiltration of water influences the progression of deterioration and behavior within the pavement structure. The data obtained from strain gauges and earth pressure gauges installed within the pavement indicated that the compressive strain on the upper surface of the granular base layer varies depending on traffic load history and water content. However, these factors do not immediately impact the subgrade layer. Furthermore, it was suggested that a capillary barrier is functioning between the upper and lower base layers.

 In Japan, expressway pavement repairs have shown a deepening of damaged layers and shortening of repair cycles due to aging and the application of porous asphalt to the surface layer. Therefore, the concept of preventive maintenance—repairing before damage worsens—is important. In this paper, analyses were conducted using repair history and pavement condition data from the Pavement Management System (PMS) to examine preventive maintenance strategies. First, we analyzed the effectiveness of early repairs by investigating the relationship between the timing of the first repair and the service life of repair layers in a section of an expressway. Next, to evaluate the bearing capacity of the asphalt concrete layer, we improved an FWD prediction model based on machine learning to supplement deflection measurements from FWD testing. Furthermore, we analyzed temporal changes in bearing capacity using the prediction model and proposed a management method for the bearing capacity of the asphalt concrete layer based on a case study of sections with repeated repairs.

 Tsuruga section is a part of Hokuriku Express Highway and operated by Central Nippon Express Highway Corporation (C-NEXCO). This section has 11 tunnels in about 50 km length. These tunnels were constructed and paved with concrete pavement 45 years ago. The 45 years old concrete pavements are still serving, even though they have been partially repaired. Quite recently, however, severe deteriorations like spalling, faulting, and cracks appear at many transverse joints and some of them should be repaired as early as possible. To grasp the entire joint conditions in this concrete pavement section, FWD tests were 2conducted and FWD data was back calculated with a consideration of joint degradation process. Based on the results, fatigue analysis was performed to estimate the fatigue life of the degraded joints. Then, a reasonable rehabilitation strategy of concrete pavement in tunnel was established. The strategy specifies to restor the degraded joints in order of the least fatigue life.

 It is important to evaluate the long-term performance for utilizing concrete pavement more in the right place and right way. Moreover, the effect of wire mesh is controversial on its costs and benefits, although it is often installed in joint concrete pavement. This research conducted the follow-up survey on a section of concrete pavement in Hiraizumi Bypass of Route 4, which has served for 24 years. We also applied for back-analysis of FWD data to evaluated the long-term structural performance and the effect of wire mesh. The result shows the concrete pavement keeps an appropriate service level, although some slabs have been cracked. It was not clear that wire mesh keeps crack opening tight. On the contraly, it was found that it caused potholes on the surface.

 It is said that the relationship between the arithmetic mean roughness Ra of micro-textures of concrete pavements and Skid Resistance before and after abrasion is different. In order to clarify the cause of this, we investigated the factors affecting Skid Resistance by macro and micro textures before and after wear using Ra. And the loaded length ratio Rmr in accordance with JIS B 0671-2. The results showed that the microtexture Ra correlated well with smooth and worn surfaces such as tunnel road surfaces with reduced Skid Resistance. However, it was suggested that the index was susceptible to the influence of macro-texture due to the initial status of broom drag formation and the residual status of broom drag subjected to wear action. Therefore, we proposed a model for predicting skid resistance that combines Rmr, which is less sensitive to broom drag, and Ra, which is less sensitive to smooth surfaces.

 This study investigated plant-based recycled asphalt mixture without fossil fuels. One of the background of this study is the desire to introduce alternative materials to petroleum asphalt due to the decline in oil demand in recent years. Another background is a need to make effective use of asphalt pavement waste materials from the perspective of creating a recycling-priented society. As a result, it was confirmed that the chemical composition and the dynamic viscoelasticity of the old asphalt coated on recycled aggregate was recovered from the deteriorated state by combining with plant-based asphalt. And it was clarified that the resistance to rutting and fatigue cracking of plant-based recycled asphalt mixture shows equivalent performance as general asphalt mixture. In addition, the constructability of this asphalt mixture was shown to be good by trial construction. Therefore, it was found that plant-based recycled asphalt mixture can be used as hot mixture for paving.

 Some commonly used jointed reinforced concrete pavements on national highways in cold, snowy Hokkaido have been reported to be in service in a relatively sound condition for nearly 30 years. However, cracks, potholes, and other damage to the pavement surface, as well as damage along the joints, have been observed recently in jointed reinforced concrete pavements that have been in service for long periods. This paper reports on field investigations into the causal factors of damage to concrete pavements that have been in service for long periods. It also reports a case study of test construction using stainless steel dowel-bar and omission of steel mesh to clarify measures against distress of jointed reinforced concrete pavements.

 A survey of concrete mixes applied to jointed plain concrete pavements at airports throughout Japan was conducted with the aim of preparing reference data on the mixes for airport pavement. The results showed that the increasing factor for nominal flexural strength was around 1.2, and, in the case of the concrete whose slump is 2.5 cm, water cement ratio was often around 40%, water content per unit volume of concrete was around 145 kg/m³, and cement content per unit volume of concrete was around 360 kg/m³.

 In block pavement, typically 100x200mm interlocking blocks and the like are used for roadways. However, from the perspective of creating and enhancing superior landscape aesthetics, there has been an increasing number of cases where larger blocks are utilized in residential areas and on shared pedestrian and vehicle streets in shopping districts. Just as in regular block pavement, it is important to grasp the bearing capacity in large-plate block pavement to ensure service performance. Therefore, we constructed test pavements by altering factors such as base course thickness and laying methods, and then carried out bearing capacity evaluations using a HFWD device. As a result, we were able to grasp the influence of various conditions on the bearing capacity of large-plate block pavement. Moreover, based on the measurement results from the conventional IL block pavement, the KP.FWD for the large-plate block pavement with a surface deformation coefficient of 214 MPa or more is 352 MN/m³. This suggests that ensuring such a bearing capacity can secure the structural integrity of large-plate block pavement.

 Pavement inspections carried out on national roads under direct control are basically carried out by ‘visual inspection’, which requires a great deal of work by sub-station staff, so an efficient inspection method is being investigated. This paper investigates the possibility of screening in pavement inspection using ‘roughness indicators’ obtained from connected cars. In the study, the threshold values of roughness indicators for screening were examined using statistical methods (ROC curves, logistic regression), using the extracted ‘pavement inspection result data’ and ‘roughness indicators’ obtained from connected cars, and the validity of the examined threshold values was verified using the ‘screening rate’. From these results, it was confirmed that the ‘roughness index’ can be used as a screening indicator for pavement inspection on single-lane sections.

 The deterioration of pavement on national highways were confirmed in Nagano Prefecture. To identify the factors contributing to the pavement damage prior to implementing repair design, a detailed investigation was conducted primarily using large-core sampling. The results confirmed the condition of damage in the asphalt concrete layer, the coefficient of subgrade reaction on the upper subgrade, and the feasibility of sampling for laboratory tests. This method was deemed effective for elucidating the factors causing pavement damage. However, it was also found that the quantity of samples obtainable and the assessment of coefficient of subgrade reaction in the depth direction could not be conducted to the same extent as with excavation surveys. Therefore, it is deemed necessary to continue investigating similar surveys to establish a detailed investigation method centered on large-core sampling.