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

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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