一般に圃場は硬い耕盤の上に軟弱な作土が存在する２層構造を呈し，均質半無限地盤とは異なる支持力特性を示すと考えられる。本研究では，車両の合理的な設計指針を得るため，耕盤のある圃場における車両の支持力問題を剛盤上の土に２つの近接する荷重が作用する平面ひずみ問題として理想化し，すべり線解法を導入して理論的解析を行った。荷重下に生じるすべり線場として，荷重幅および荷重間隔に応じた5種の干渉状態のすべり線場を提示した。

A Slip-Line Analysis for the Bearing Capacity of Farm Land on a Sole Pan (Part 1)　-Interfering Slip-Line Fields-

Bearing capacity of farm land which generally consists of soft soil on hard sole pan differs from that of homogeneous semi-infinite ground. In this study the bearing capacity of farm land for a vehicle which is regarded as two adjacent loads penetrating into soil on rigid pan in plane strain is analyzed by the slip-line method in order to establish a reasonable designing method for the traveling device of vehicles. Five types of the slip-line field are proposed for variation of load width and its interval.

[Keywords] vehicle, bearing capacity, slip-line field, rigid plasticity, plane strain, sole pan