| 摘要 |
<p>PURPOSE:To enable accurate measurement by a method wherein a plurality of strain gauges are provided on the surface of a steel material along the length thereof and measured values of stresses at the right angle to the steel material from the strain gauges is checked to detect a loosening of a subsoil from a changing point of a stress distribution graph. CONSTITUTION:A hole is excavated toward a measuring subsoil from the inside 1 of a tunnel pit and above the earth, a measuring instrument 3 is inserted into the hole 2 excavated and a surrounding gap is filled with a hardening agent 4 to be integrated firmly with the subsoil. Here, the measuring instrument 3 has a web of a steel material 5 such as H-shaped steel provided with a required number of strain gauges 6 at the right angle to the axis line along the length thereof and is covered with a coating material 7 and a foaming synthetic resin layer 8. Then, distortions of the subsoil at the right angle to the steel material 5 are measured with the strain gauges 6. A stress distribution graph is prepared based on the distortions thereby enabling detection of a loosening of the subsoil from a changing point of the stress distribution graph corresponding to a measuring point.</p> |
