ABSTRACT

This study to estimate discharge capacity considering clogging and consolidation effects led to a development of the composite discharge capacity apparatus, followed by a series of tests with Prefabricated Drain Board (PDB) and Fiber Drain (FD). The laboratory test is done to simulate the conditions for the deformation of in-situ drain by installing the drain on the clay layer (wi=92.4%) and applying pressure on its upper part, which procedure shows a simulation where the drain is vertically installed on the surrounding ground.

INTRODUCTION

When it comes to the discharge capacity of drain installed underground, its inner and outer clogging, its creep, some deformation (bending) resulting from the settlements of the ground, and water which gets turbulent in the PDB thanks to an increase in hydraulic gradient lead the capacity to get lower (Table I). Generally, in laboratory discharge capacity tests, field conditions are modeled by applying a fixed lateral pressure with the use of water pressure in the tester where the drain is wrapped up with a rubber membrane or clay is put between the drain and the membrane. In case of the former test, the membrane could be an obstacle to deliver confining pressure directly to the drain because it has its own tension strength.

2. COMPOSITE DISCHARGE CAPACITY TEST
2.1 COMPOSITE DISCHARGE CAPACITY APPARATUS

For the study, a composite discharge capacity apparatus as shown in Fig I is prepared to identify discharge capacity under a fixed surcharge pressure, which would be applied after drain has been installed. The tester that could be divided into three layers IS made of cylindrical steel frame with 50cm in its diameter and I00cm in its height. In order to measure pore pressure with consolidation in progress, ports is installed every IOcm on its either sides.

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