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ABSTRACT Oya tuff has been used as a building stone for more than 100 years and some collapses of abandoned underground quarries occurred in recent years. The time-dependent response and monitoring of these abandoned underground quarries are of great importance. An in-situ acoustic emission-monitoring program has been used for some time in Oya region in order to warn people before their collapse. The authors have been doing some experimental studies on the creep behaviour of Oya tuff and exploring the utilization of multi-parameter approach for such stability assessments. The authors will report some experimental results on multi-parameter responses of Oya tuff during compression, Brazilian and impression creep experiments in this study. INTRODUCTION The utilization of multi-parameter responses of rocks for assessing the short and long-term stability of rock structures as well as earthquake prediction has been becoming an important topic in geomechanics and geoengineering in recent years. The authors have been carrying out some experimental studies on various rocks under different loading regime for some time [1,2,3,4]. Multi-parameter measurements involve measurements of acoustic emission, electrical potential, electrical resistivity, elastic-wave velocity in addition to conventional load (stress) and displacement (strain). Creep and relaxation experiments are often carried out to determine time-dependent characteristics of rocks [5]. The authors have been performing creep and relaxation experiments on soft rocks under compression and tensile stress environment [6,7]. They also initiated a new experimental program on the creep and relaxation penetration (impression) experiments, which may be used as a practical tool to obtain the time-dependent characteristics of rocks. A series of experiments for the creep characteristics of Oya tuff as one of well-known soft rocks in Japan undertaken by the authors at Tokai University and Toyota National College of Technology using uniaxial compression, Brazilian creep and impression creep testing methods. The multi-parameter responses of Oya tuff in uniaxial compression, tensile and impression experiments carried out under creep or relaxation loading regimes are presented in this article and their implications are discussed. GEOLOGICAL CHARACTERISTICS OF OYA TUFF Oya tuff or Oya stone, which is one of the most popular building stone materials in Japan, has been quarried in the Oya region, Utsunomiya, Japan. Over 200 underground quarries (Figure 1) have been exploited for more than 100 years and some of those are below residential areas [8]. It became famous as a building stone following its use in the construction of Imperial Hotel in Tokyo. The mechanical excavation using chains started in 1952 and the size of quarries become larger as a result. The first caving of the quarries occurred in 1946 and there were very large scale caving (sinkholes from 1989 to 1991, which received wide coverage by the mass media (Fig. 2). As a result, Utsunomiya City started long-term monitoring of abandoned underground quarries using acoustic emission technique. Furthermore, these events also resulted in the increased attention on the long-term stability of Oya tuff underground quarries. The failure of an underground quarry occurred in 1989 in Sakamoto district of Oya town. The diameter of the sinkhole was about 65 m and the overburden thickness was 30m and the total depth of the sinkhole was 40m.
- Geology > Structural Geology > Tectonics > Plate Tectonics > Earthquake (1.00)
- Geology > Mineral (0.95)
- Geology > Geological Subdiscipline > Geomechanics (0.91)
University of the Ryukyus, Dept. of Civil Eng., Japan *takito@tec.u-ryukyu.ac.jp Abstract Tuff, which is sedimentary rock consisting of volcanic ashes, has been used as building stone for centuries worldwide and some collapses of abandoned underground quarries occurred in recent years. The time-dependent response and monitoring of these abandoned underground quarries are of great importance. The authors have been carrying out some experimental studies on the creep behavior of tuffs from Japan and Turkey utilizing creep tests subjected to different loading regimes such as uniaxial or triaxial compression, Brazilian tensile, bending as conventional creep tests and impression creep tests as index test. The authors report some experimental results on time-dependent characteristics of tuffs during uniaxial and triaxial compression, Brazilian and impression creep experiments in this study. The experimental results are compared with each other for the suitability for creep characteristics and their implications are briefly discussed.
- Asia > Japan (0.71)
- Asia > Middle East > Turkey (0.26)
- Geology > Geological Subdiscipline > Volcanology (0.89)
- Geology > Geological Subdiscipline > Geomechanics (0.72)
- Geology > Structural Geology > Tectonics > Plate Tectonics > Earthquake (0.47)
ABSTRACT: The authors have been concerned with time dependent properties of the tuffs of Cappadocia Region where many semi-underground or underground antique and modern structures exist. Tuff samples obtained from outcrops in the localities of Derinkuyu, Avanos, Ürgüp, Özkonak and Zelve. A series of Brazilian, 3-point bending and uniaxial compression creep experiments were carried under both dry and saturated conditions. During these tests, Acoustic Emission (AE) measurements were also conducted to investigate the fracturing phenomenon. The authors present the outcomes of the creep experiments on these tuffs and discuss their implications for the long-term behaviour of rock masses associated with antique rock structures. 1 INTRODUCTION Many semi-underground or underground antique and modern structures exist in Cappadocia Region of Turkey. Most of these structures were excavated more than, at least, 1500 years. These structures are the best examples of long term performances of man-made structures in the field of rock engineering. An experimental study on the long term behavior of the Cappadocian tuffs in association with the long term stability of various antique underground or semi-underground structures was been initiated by the authors as a part of an international joint project between Japan and Turkey (Aydan et al. 1999a). This experimental programme has been continued by the authors. Besides uniaxial creep experiments, a series of Brazilian and 3-point bending and uniaxial compression creep experiments were carried under both dry and saturated conditions. During these tests, Acoustic Emission (AE) measurements were also conducted to investigate the fracturing phenomenon. Furthermore, some index creep tests were carried out using impression creep testing technique. Tuff samples were obtained from outcrops in the localities of Derinkuyu, Avanos, Ürgüp, Özkonak and Zelve. In this study, the outcomes of experimental tests on tuff samples under different creep conditions are presented and their implications are discussed with the consideration of long-term performance of many antique semi-underground and undergound structures in Cappadocia region.
- Asia > Middle East > Turkey (1.00)
- Asia > Japan (1.00)
- Energy > Oil & Gas > Upstream (0.70)
- Government > Regional Government > Asia Government (0.47)
Impression Relaxation Test, a New Relaxation Method to Determine the Time Dependent Characteristics of Salt Rock
Mehranpour, M.H. (School of Mining Engineering, The University of Tehran) | Rassouli, F.S. (Graduate student of School of Mining Engineering, University of Tehran) | Moosavi, M. (University of Tehran)
ABSTRACT: Relaxation impression technique is a novel relaxation test in which a cylindrical flat ended indenter penetrates into a small region of sample and after keeping the displacement at a certain point, the decrease in the stress level will be recorded. Conventional relaxation test is a time consuming and expensive technique when a number of samples are needed to be tested. In contrast, impression relaxation test requires only a small amount of sample which makes this method cheaper. In this study, the impression relaxation test will be carried out on salt rock using an apparatus, which is designed and fabricated for impression relaxation test, and the results will be compared to the results of conventional compression relaxation test. 1. INTRODUCTION There is a strong demand for constructing deep underground spaces in many fields of rock engineering such as mining activities and petroleum production. As a result, defining characteristics of time-dependent deformations and failure around the underground openings are a major concern for stability and safety of structures. Creep under constant stress and relaxation under constant strain are two typical time-dependent phenomena of materials. In natural geological systems true creep or relaxation is, however, hard to be implemented, because a combination of creep and relaxation is commonly observed [1]. When a constant strain is applied to a viscoelastic material, which behaves in a nonlinear, and non-Hokean fashion, the force necessary to maintain that strain is not constant but decreases with time. This behavior is called .stress relaxation.. Conversely, when a viscoelastic material is subjected to a constant stress, an increase in the deformation takes place with time; this behavior is called .creep.. The processes causing stress relaxation may be physical or chemical in nature, and under all normal conditions, both types of processes will occur simultaneously.
- North America > United States (0.28)
- Asia > Middle East > Iran (0.16)
Creep Characteristics Of Tuff In The Vicinity Of Zelve Antique Settlement In Cappadocia Region Of Turkey
Ito, T. (Toyota National College of Technology) | Aydan, O. (Tokai University, Department of Marine Civil Engineering) | Ulusay, R. (Hacettepe University, Geology Engineering Dept) | Kasmer, O. (Bayindirlik ve Iskan Bakanligi)
Abstract The semi-undergound structures in Zelve and Göreme have been particularly deteriorating rapidly and some major collapses occured in recent decades. A series of preliminary tests on the water migration characteristics, mechanical properties and the effect of water content on their mechanical and physical properties and creep tests on rock samples from Zelve antique settlement have been carried out. The present paper mainly presents the results of the creep tests under uniaxial compression stress and tensile stress conditions under dry, saturated or mixed conditions. The results presented in this article also indicate that time depend. 1. Introduction The Cappadocia region of Turkey is one of the cultural heritage of Mankind and it has many underground or semi-under-ground cities, towns and settlements. The preservation of this cultural assets is of great importance for the world. The preservation as well as restoration of these historical remains require basic understanding of surrounding rock under various environmental conditions. Compared to underground structures, surrounding rock of semi-underground structures are much prone to physical and chemical weathering and degradation of rock properties. The major semi-undergound settlements and many historical assests are found in Zelve, Göreme, Ihlara and Ürguep (Figure 1). The semi-undergound structures in Zelve and Göreme have been particularly deteriorating rapidly in recent decades and some major collapses occured as seen in Figure 2. There are many historical structures of great importance in three valleys of the Zelve Open-air Museum (Figure 3). The urgent measures are necessary to prevent the collapse and/or further deteriorations of these semi-undergound structures. Some rock blocks are collected and samples are prepared at Hacettepe and Tokai Universities. A series of preliminary tests on the water migration characteristics, mechanical properties and the effect of water content on their mechanical and physical properties and creep tests have been carried out. The present paper mainly presents the results of the creep tests under uniaxial compression stress and tensile stress conditions under dry, saturated or mixed conditions. The results to be presented in this article also indicate that time dependent behavior of tuff of Zelve has an important effect on the time of failure of semi-underground settlements.. 2. Geology The Cappadocia Region geologically covers approximately an area of 40000 km2. In addition to rhyolitic and dasitic tuffs, andesite and basalt originated lava can be seen in the area formed during the volcanic activity between Upper Miocene and Quaternary (Figure 4). The Ürguep formation, which shows the largest distribution in the region, includes a number of different tuff and lava layers. Zelve member, one of these tuff layers, is in the form of a single pyroclastic flow unit and at its base there is a Plinian air-fall deposit of 5–12 m thick. The thickness of this member reaches up to 100 m with an average of 60 m (Temel et al. [1]).