Estimating the yield zone boundaries of weak zone of in underground openings by pressuremeter tests: a case study in Can
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ORIGINAL PAPER
Estimating the yield zone boundaries of weak zone of in underground openings by pressuremeter tests: a case study in Canakkale, Turkey Celal Agan 1 Received: 19 July 2019 / Accepted: 20 March 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The use of rod extensometers is one of the most commonly used monitoring methods for the prediction of yielding zones of underground openings. However, this method requires expensive and long-term measurements. In this study, comprehensive investigations were carried out to determine the performance of the pressuremeter test as for rapid in situ measurement methods to expeditiously estimate the boundary of the yielding zone. An unstable tunnel of the Cokal Dam in Gelibolu County of Canakkale was chosen for investigations. Laboratory tests, drilling, topographic measurements, pressuremeter tests, and rod extensometer measurements were performed in order to assess the instability and to determine the boundaries of the yielding zone. The in situ tests revealed that the boundaries of the weak zone, determined using the pressuremeter tests, was in good agreement with the failure depths determined by the rod extensometer measurements. Keywords Yield zone . Pressuremeter . Rod extensometer . Cokal
Introduction One of the major problems in geotechnical engineering is to determine the boundaries of the weak zone in tunnels. Wrong prediction of the yielding zones can lead to very dangerous and costly results. Although there are some methods used to predict or determine the yielding zones, the rod extensometer is the most commonly used monitoring method for this purpose (Aksoy et al. 2014; Gage et al. 2013; Song et al. 2012; Unlutepe and Ozener 2008; Lin and Tang 2005). However, this method has the drawback that it requires demanding and long-term measurements. Therefore, more convenient methods are needed for the rapid and lower-cost determination of the boundaries of the yield zone expeditiously. In this study, comprehensive investigations were carried out to examine the performance of the Menard pressuremeter test (MPT) as an in situ measurement method to expeditiously estimate the boundaries of the yield zone around the tunnel.
* Celal Agan [email protected]; [email protected] 1
Department of Civil Engineering, Harran University, 63000 Sanliurfa, Turkey
MPT was developed in the 1950s by Louis Menard. The test is described and discussed in ASTM D4719 (2007), Mair and Wood (1987), Baguelin et al. (1978), and Centre D Etudes Menard (1975). MPT was developed to predict the ultimate bearing capacity and the settlement of a foundation. Since a quite large volume of soil in its in situ condition is tested, the MPT may be the most suitable method for those soils—where it is difficult to obtain samples. MPT has been used for different purposes by some researchers. For example, Agan (2014) determined the deformation modulus of dispersible-intercalated-jointed cherts using the MPT. Agan and Unal (2013) investigated the performance of the MP
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