Takaaki Mizutani

Manufacture of Bonded Granular Soil Using X-Ray CT Scanning and 3D Printing

This paper describes the use of X-ray tomography imaging of natural gravel specimens to create repeatable assemblages of bonded gravel-size resin specimens using a 3D printer. The paper describes how the resulting resin-based surrogate specimens have particle geometry and interparticle bonds that are a function of the original scanning image resolution and 3D printer resolution. Results of conventional triaxial compression testing of original source gravel specimens and constructed bonded specimens are compared. While there are quantitative differences in behavior between unbonded source and bonded duplicate specimens, the surrogate specimens are shown to have macroscale mechanical behavior that may be considered typical of some granular soils. The ability to generate identical surrogate bonded granular specimens with the same particle arrangement holds promise to remove the influence on geotechnical laboratory testing outcomes due to the unavoidable structural variation in specimens of natural granular assemblages.

EVALUATION ON PLASTIC DEFORMATION PROPERTY OF ASPHALT MIXTURE UNDER HIGH CONTACT PRESSURE

The paper reports results of the investigations on plastic deformation property of asphalt mixture under high contact pressure. Resistance to plastic deformation under high contact pressure was evaluated by means of Wheel Tracking (WT) test machine for simulating aircraft repetitive loadings. On the other hand, the author suggested the method for evaluating continuous air voids distribution of asphalt mixture in the depth direction by X-ray CT (computed tomography) scanner, and then tried to evaluate the property of the test specimen after the WT tests by using the method. As a result, following conclusions were shown. 1) The consolidated deformation under 1.48MPa contact pressure was larger than that under 0.63MPa contact pressure. 2) Void ratio of upper part of tested samples was less than that of samples before test whether the contact pressure was 1.48MPa or 0.63MPa. 航空機接地圧下におけるアスファルト混合物の塑性変形特性について，走行荷重に対するアスファルト混合物の塑性変形抵抗性および深さ方向の空隙分布の変化に基づき調査した．まず，WT試験機により航空機接地圧下でのアスファルト混合物の塑性変形抵抗性を評価した．次に，X線CTスキャナによるアスファルト混合物の深さ方向の空隙分布評価方法を検討し，これによりWT試験前後の車輪走行部の深さ方向の空隙分布の評価を試みた．その結果，航空機接地圧下では自動車接地圧と比較し圧密変形量が大きくなることやWT試験後の供試体上部の空隙率が接地圧の大小に関わらず試験前と比較し顕著に小さくなることなどを示した．