Yeraltı suyu akımı etkisinde 45 derecelik şevde oluşan kumlu tın toprak erozyonunun deneysel incelenmesi

Year 2018, Volume: 24 Issue: 6, 967 - 973, 18.12.2018

Onur Akay

Abstract

Yeraltı
suyu akımları doğal şevlerde toprak kaymasına; toprak dolgu şevlerde ve
barajlarda da sığ ve derin kayma yüzeyli göçmelere yol açan erozyonun başlıca
etkeni olabilmektedir. Bu çalışmada, yeraltı suyu akımı kaynaklı erozyon
mekanizmaları kumlu tın toprak kullanılarak inşa edilmiş üç-boyutlu fiziksel
şev modeli ile incelenmiştir. Bu amaçla, laboratuvarda 100 cm uzunluğunda, 50
cm genişliğinde ve 60 cm yüksekliğinde bir erozyon kanalı inşa edilmiştir.
Homojen bir kumlu tın fiziksel modeli elde edebilmek için 45 derecelik yüzey
açısında sahip olan şev 2.5 cm yüksekliğinde basamaklar halinde kontrollü
olarak sıkıştırılmıştır. Yeraltı suyu erozyon kanalının bir tarafında bulunan
su haznesinde uygulanan 50 cm-su piyezometrik yük altında oluşturulmuştur. Su haznesinden
(memba) akışa geçen yeraltı suyu erozyon kanalının diğer tarafındaki şev
yüzeyinden (mansap) sızma suyu olarak çıkış yapmıştır. Toprak partikülleri
doygun durumdaki şev yüzeyinden çıkış yapan sızma suyu tarafından
sürüklenmiştir. Sızma suyu erozyonunun oluşturduğu oyuk deney süresince memba
kesimine doğru toprak kaymaları ile ilerlemiş ve yüksekliği deney sonunda şev
kretine kadar ulaşmıştır. Şev erozyonunun kararlı akım durumundaki boşluk-suyu
basınçlarına bir etkisi olmamıştır.

Keywords

Yeraltı suyu akımı, Sızma erozyonu, Erozyon kanalı, Sediment taşınımı

Experimental investigation of sandy loam soil erosion on a 45-degree slope under the effect of groundwater flow

Abstract

Groundwater
flow is considered as a major contributor for erosion that may result in
landslides of natural hill slopes and shallow and deep-seated failures of
engineered embankments. In this study, erosion mechanisms of a sandy loam slope
due to groundwater flow were investigated using a three-dimensional physical
model. For this purpose, an erosion flume with dimensions of 100 cm long, 50 cm
wide and 60 cm high was constructed in the laboratory. The physical slope model
with a 45 degree slope angle was compacted in 2.5 cm lifts to obtain a
homogenous sandy loam slope. The groundwater flow was generated under a
piezometric head of 50 cm-water that was applied at the water reservoir located
at one end of the erosion flume. The groundwater flow directed from the water
reservoir (upstream) seeped out of the slope surface at the other end of the
flume (downstream). Soil particles became entrained in the seepage flow that
exfiltrated the slope surface at the saturated zone. The extent of the cavity
due to seepage erosion progressed upstream via sapping during the experiment
and the height of the cavity reached the crest of the slope at the end of the
experiment. Seepage erosion did not affect the steady-state pore-water
pressures.

Keywords

Groundwater flow, Seepage erosion, Erosion flume, Sediment transport

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