Determination of the Deformability, Modulus Ratios and Anisotrophic Behavior of the Micaschists; A Case Study From Burgaz Dam Site, Izmir-Turkey

Year 2019, Volume: 43 Issue: 2, 155 - 185, 15.01.2019

Serkan Uslu Mehmet Yalçın Koca

https://doi.org/10.24232/jmd.654888

Abstract

Base rock of the Burgaz dam in the eastern part of the city of İzmir consists of micaschists having different physical and mechanical properties due to weathering and fracturing. The first aim is to compute the amount of settlement and ultimate bearing capacity value of micaschist both in and beneath the cutoff zone by using the results of pressuremeter tests. In addition, data from in-situ and some laboratory tests, which were used in the establishment of the relations between elastic modulus of the micaschist rock mass (EM) and uniaxial compressive strength (σc), EM/Eintact ratios and RQD values. Comparison of in-situ and estimated rock mass deformation moduli by considering the RQD values was also performed. Pressuremeter tests indicate that for a dam with 115 m height and a base width of 58 m, the settlement will vary between 2.13 and 2.26 mm. The second aim of this work is to measure compression and shear wave velocities in order to obtain both the ratio of dynamic elastic modulus to Poisson′s ratio (E/v) dynamic and to compare (E/v)dynamic to (E/v)static. Test results reveal a positive linear relation of (E/v) dynamic =(E/v) static0.968. The sonic wave velocity of the micaschist is highly related to the testing direction. This study not only discusses the relationships between Estatic and sonic wave velocity (Vp) and Edynamic, but also the anisotropy effect arisen due to the schistosity planes with different orientations.

Keywords

Dam structure, micaschist, pressuremeter test, settlement, rock material classification, anisotropy

Mikaşistlerin deformabilite, modül oranı ve anizotropik davranışlarının belirlenmesi; Burgaz baraj sahasından (İzmir-Türkiye) örnek bir çalışma

Abstract

İzmir′in doğusunda yeralan Burgaz barajının temel kayacını ayrışma ve kırıklanma nedeniyle farklı fiziksel ve
mekanik özelliklere sahip mikaşistler oluşturur. Bu çalışmanın birinci amacı, presiyometre deneylerinin sonuçlarını
kullanarak hem cutoff zonunda hem de altında yeralan mikaşistlerin nihai taşıma güçlerini ve oturma miktarlarını
hesaplamaktır. Buna ek olarak, bazı laboratuvar ve yerinde deneylerden elde edilen veriler, mikaşist kayaç kütlesinin
elastisite modülü (EM) ve sağlam kayanın tek eksenli sıkışma dayanımı (σc), Em
Ei oranları ve RQD değerleri
arasındaki ilişkilerin kurulmasında kullanılmıştır. Mikaşist kayaç kütlesinin yerinde ölçülmüş elastisite modülü
değerleriyle, RQD değerlerini dikkate alan tahmin edilmiş elastisite modülü değerleri karşılaştırılmıştır. Presiyometre
deney sonuçları, 58 m taban genişliğine ve 115 m yüksekliğe sahip bir baraj için oluşacak oturmaların 2.13 mm ile
2.26 mm arasında değişeceğine işaret etmektedir. Bu çalışmanın ikinci amacı; ultrasonik dalga hızlarından (Vp ve

Keywords

Baraj yapısı, mikaşist, Presiyometre deneyi, oturma, kaya materyali sınıflaması, anizotropi

References

• Al-Shayea, N.A., 2004. Effects of testing methods and conditions on the elastic properties of limestone rock. Engineering Geology, 74, 139-156. Anon, 1979. Classification of rocks and soils for engineering geological mapping, Part 1 – Rock and soil materials. Bull. Int. Ass. Engineering Geology, 19, 364 – 371. Anon, 1981. British Standard 5930: Site Investigations, London. British Standards Institution, pp. 147. Andrade, P.S., Saraiva, A.A., 2010. Physical and mechanical characterization of phyllites and metagreywackes in central Portugal. Bull. Eng. Geol. Environ., 69, 207-214. ASTM D 2845-08, 1990. Standard Test Method for Laboratory Determination of Pulse Velocities and Ultrasonic Elastic Constants of Rocks, American Society Testing Materials. ASTM D 2938-95, 1992. Standard Test Method for Unconfined Compressive Strength of Intact Core Specimens. Rock testing handbook, 89-111. Baguelin, F., Jézéquel, J.-F., Shields, D.H., 1978. The pressuremeter and foundation engineering. Clausthal: Trans Tech Publications. Behrestaghi, M.H.N., Rao, K.S., Ramamurhy, T., 1996. Engineering geological and geotechnical responses of schistose rocks from dam project areas in India. Engineering Geology, 44 (1 – 4), 183 – 201. Birid, K.C., 2015. Interpretation of pressuremeter tests in rock, ISP7-PRESSIO 2015, Frikha, Varaksin&Gambin (Eds), Conference paper, pp. 289 – 300. Brotons, V., Tomas R., Ivorra S., Grediaga A., 2014. Relationship between static and dynamic modulus of a calcarenite heated at different temparatures: the San Julian′s stone. Bull. Eng. Geol. Environ, 73, 791–799. Brotons, V., Tomas R., Ivorra S., Grediaga A., Martinez T.M., 2016. Improved correlation between the static and dynamic elastic modulus of different types of rocks. Material and Structures, 49, 3021 – 3027. Christaras, B., Auger, F., Mosse, E., 1994. Determination of the moduli of elasticity of rocks. Comparison of the ultrasonic velocity and mechanical resonance frequency methods with direct static methods. Materials and Structures, 27, 222–228.