Teru Yoshida

Impact Based Testing Technique for Measuring Moduli of Geomaterials

This paper presents a method that measures an impact process of a spherical object colliding with on a testing material and, through analytical techniques based on Hertzs theory of impact, deduces the elastic modulus of the tested material. Furthermore, by distinguishing the compress and rebound phrases, and by accounting for the plastic deformation characteristics of the tested material, this method can measure the compressive modulus and rebound modulus simultaneously. This method is suitable for testing various materials, such as steel, concrete, and geomaterials including cement-treated soils. Various deformation parameters can be deduced from this method, including compressive modulus, subgrade soil modulus K30, California Bearing Ratio (CBR) value, and Benkelman Beam Deflection value. This method is shown to be very accurate in a large number of validation tests performed by the authors. Its advantages include broad applicability, high efficiency, and relatively large strain (thus also capable of evaluate material strength). Results from field implementation in actual civil projects show that this method has great potential in many applications, particularly real-time fill materials quality assurance and construction optimization.

CONSTRUCTION OF A LATTICE-FRAME-REINFORCED SHEET ON THE SOFT GROUND

格子ジャケットを用いたシート工法は，筒状織物に流動性の高いモルタルを充填して格子状の補強枠を形成する表層安定処理工法で，格子構造が荷重分散効果を有し，軟弱地盤上に施工することで不同沈下の抑制が行える．これまでに水田上におけるトラフィカビリティーの改善実験や鉄道路床の試験施工，および河川護岸工事における短期間の仮設道路としての使用などの実績がある．本報告では深さ10m近くまでN値の低い地盤が堆積している軟弱地盤上に一般道路の仮設道路として施工した例を紹介すると共に，使用期間が1年以上と比較的長期にわたるため，追跡調査を行い施工後の状況について詳細調査を行った結果を報告する．

Experimental Estimation of Adfreeze Shear Reinforcement at Joint between Frozen Soil and Underground Structures

Recently artificial ground freezing has become more frequently used for construction of underground facilities in urban areas because it makes underground excavation possible without lowering the groundwater level. To use artificial ground freezing in a underground excavation project, the adfreeze shear strength at the joint between an underground structure and frozen soil should be large enough to ensure structural stability. For that reason, the authors have previously proposed a method for enhancement of adfreeze shear strength by the use of stud connectors. This paper addresses a series of small-scale laboratory tests and large-scale verifying experiments that help formulate reinforcing effects of the proposed stud connectors on the adfreeze shear strength.