The drainage system performance in peat soil with permeability reduction

Andrey Nikitin,Olga Zaborskaya,A Zheltenkov

doi:10.1051/e3sconf/20199107013

Andrey Nikitin, Olga Zaborskaya + Show 1 more

Open Access

https://doi.org/10.1051/e3sconf/20199107013

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Abstract

Construction in waterlogged areas requires special design solutions and expensive site preparation works. Operating experience shows that the efficiency of drainage systems in peat soil decreases over time. This article describes factors to be taken into account when designing drainage systems in peat soil. It also summarizes the results of the laboratory surveys for peat and filling material permeability reduction over time. We used a laboratory box to study water permeability over time. In the experiment, we used poorly decomposed peat of natural structure and compacted peat. The study found that the water inflow into the drainage system decreased 1.5 to 1.7 times in the course of filtration. The greatest peat permeability reduction was recorded at the initial stage. The article demonstrates how the grain-size composition of sand used as backfilling affects its water permeability. In order to ensure normal operation of drainage systems in peat soil, one must consider the reduction of peat water permeability over time and clogging of sand filling when designing the said systems.

Highlights

Construction in waterlogged areas requires site preparation
The drainage system is made of perforated asbestos-cement or plastic pipes 150 to 300 mm in diameter with wrapping filters and stone covers
Geotextile membranes are generally used for filter covers, and 5 to 40 mm grain size crushed stone is used for stone covers

Summary

Introduction

Construction in waterlogged areas requires site preparation. Considering the engineering complexity and high cost of full peat reclamation, site preparation usually involves peat surcharging with sand and water level depression. Each support rests on two reinforced concrete piles with the cross-section of 300×300 mm. Cast-in-place reinforced concrete grillage is installed over the pile tops. - Reduced water permeability of filling material and filter covers with mineral and organic particles carried over by groundwater. Contributes to reducing the peat permeability factor over time. This is related to the blocking of pores with fine particles contained in peat, as well as peat decomposition processes at temperatures above 15oС. This effect occurs if the peat layer top is substantially above the drainage system

Laboratory experiments

Analytical calculation and numerical simulation

Conclusion