การใช้เครื่องมือตรวจวัดแรงดันน้ำแบบทำงานด้วยแก๊สในดินเหนียว

Abstract

With an appropriate installation technique, this paper exhibits the effective applicability of pneumatic piezometers in detecting responses of pore water pressure in clays. Field monitoring results from the Evanston tunnel project (U.S.A.) and the Bangkok Metropolitan Authority (BMA) tunnel project are presented herein to substantiate the importance of frequent piezometric observations after backfill grouting and the necessity of piezometer installation well in advance of construction. Leaving bentonite pellets overnight shortened the stabilization time of pore water pressure after installation. However, drilling for piezometer/inclinometer installation nearby caused the increase of pore water pressure and thereby prolonged the stabilization time after installation.