VAKUM VE SERBEST ATMOSFER ŞARTLARI ALTINDA HAVADA KURU TOPRAK NUMUNESİNİ SUYA BATIRARAK ISLATMA SONUNDA ELDE EDİLEN SUYA MUKAVİM AGREGAT ÖLÇMELERİ ÜZERİNE BAŞLANGıÇ RUTUBET MUHTEVASININ TESİRLERİNİN TESBİTİ ÜZERİNDE BİR ARAŞTIRMA

Abstract

OZET Bu calisma, struktur tayininde islak-eleme ameliyesinden once, havada kuru toprak numunesini suya batirarak islatma sartlari altinda agregat parcalanmasina sebep olan kuuvvetlerin ki hapsedilmis hava ve suyun dispers etme hareketinin nasil calistiigini tetkik gayesiyle yapilmistir. Iskocya-Aberdin dolaylarindan ince kumJu-killi-tinli bir teksture sahip bir tarla topraginin ust 0-20 cm'Jik tabakasindan alinan toprak numunesi uzerinde asagidaki husus/ar bulunmu.;tur : 1) Havada kuru toprak rutubeti azalirken, hapsedilmis havanin agregat/ar uzerine parcalayici etkisi artmaktadir. 2) Bu etki, agregat buyuklugu 1 mm'nin uzerinde artarken artmistir. 3) Gerek vakum ve gerekse serbest atmosfer sart/an altinda suya batirarak is/atildigi zaman, baslangic havada kuru toprak rutubet muhtevasi artarken suya-mukavim agregat miktarlan da artmaktadir. SUMMARY Study on the Elfeet of Iniiial Soit Moisture Contetit on the WaterStable Aggregates obtained on Re-Wetting by Immersion under Vaeuum and Non- Vaeuum Conditions. This work was intended to find out how the components of aggregate breakdown due to entrapped air and the dispersing action of water work on r-e-wetting by immersion before wet-sieving. It was carried out on a soil sample of fine sandy-Ciay-loam textured and taken from the tdp 0-20 cm. layer of a field, been under grass for about 25 years, at Cruden Bay around Aberdeen, Scotland. After airdrying and screening through a 3 mm. mesh sieve, the sample was re-wetted by immersion under both vacuum and non-vacuum conditions at two levels of initiaI soil moisture content before- wet-sjeving by the method developed by Williamson et all. (1956). it was found that I) When the initial soil mOlJsture decreased, the disrupting etTect of entrapped air increased. 2) This effect was more pronounced as the aggregate size increased above i mm. in diameter. 3) Under both vacuum and nonvacuum conclitions, when the initial soil moisture content increased, the water-suible aggregates increased, when re-wetted by immersion.