Earticle

하동 쌍계사 진감선사탑비는 통일신라 후기를 대표하는 승탑비로, 전쟁과 지진 등에 의해 다양한 손상을 입은 것으로 알려져 왔다. 이 탑비의 귀부는 전형적인 화강암질 편마암 이 며 비신과 이수는 불균질한 조직을 갖는 섬록암이다. 비파괴 손상도 평가 결과, 탑비의 전체 균열지수(CI)는 5.09이나, 특히 비신의 정면에서 9.81로 매우 심한 상태를 보였다. 초음 파 속도 로 측정한 전체 석재의 물성은 모두 약간 풍화된 등급(SW)으로 비교적 건전성을 유지하고 있 다. 그러나 To-Tc 법으로 비신 균열대의 깊이를 분석하면 최소 8.97 mm가 산출된 다. 최대 심도 는 비신 두께(230 mm)를 초과하는 관통상 균열도 나타나며, 주로 비신의 상부에 밀집해 있다. 이 결과는 탑비의 안정적 보존을 위한 중요한 자료가 될 것이며, 보수 및 정비 이 후에도 주기적 모니터링을 통해 예방보존 차원의 관리가 지속되어야 한다.

The Stele of Master Jingamseonsa at Ssanggyesa temple in Hadong is a stele representing the late Unified Silla period, and has been known to suffer various damages due to war and ear thquakes. The pedestal stone of the Stele is typical granitic gneiss, while the body and the cr own stones are diorite with heterogeneous textures. As a result of the non destructive deterioration assessment, the overall crack index (CI) with the Stele was 5.09, but it showed very serious state at 9.81 on the front. The physical properties of the stones measured by ultrasonic velocity were all slightly weathered (SW) grade and maintain healthy status. However, when the crack depths in the body stone was analyzed using the To-Tc method, the minimum depth is calculated to be 8.97 mm. The maximum depth exceeds the thickness of the Stele (230 mm), and appear penetrating cracks with concentrated mainly in the upper part. These results will be important data for stable preservation of the Stele, and preventive conservation should continue through periodic monitoring even after maintenance and repair.

이 연구에서는 석조문화재의 표면 균열에 대한 깊이와 연장성을 측정하기 위해 창녕 물계서원 원정비를 대상으로 초음파 속도를 활용하였다. 또한 이 원정비의 장기적인 보존관리 방안을 수립하기 위해 재질 및 손상현황을 조사하고, 다양한 비파괴 기법을 활용하여 정밀진단을 수행하였다. 원정비를 이루고 있는 주요 구성암석은 비석의 부위에 따라 달리 알칼리장석화강암, 반려암 및 섬록암으로 이루어져 있다. 손상도 평가 결과, 특히 균열이 비신의 모든 방향에서 두드러진 분포를 보여 안정성을 저해하는 중요한 손상인자로 나타났다. 원정비 재질의 물성평가를 위한 초음파 측정에서는 비신, 대좌, 옥개석 순으로 속도가 빠르게 나타났다. 원정비에 다양한 형태로 발생한 균열들의 현황과 산출상태를 정량적으로 산출하기 위해 초음파를 이용한 To-Tc법으로 균열의 심도를 측정한 결과, 0.6∼24.1㎝로 다양한 깊이를 보였다.

To measure the depth and extension on the surface cracks of the stone monument, ultrasonic pulse velocity targeted at the Mulgyeseowon Stele in Changnyeong was used in this research. Additionally, to establish a long-term countermeasure of management and conservation for this stele, we have investigated the material properties and damage on it and have conducted a precise diagnosis by a variety of non-destructive techniques. Our research has revealed that stones of the stele are composed mainly of three rock types according to the parts of it, alkali-feldspar granite, gabbro and diorite. The result of the deterioration evaluation has occurred that cracks, which are observed from every direction in the body of the stele, are the significant factors to reduce structural stability. The ultrasonic velocity for an evaluation on the properties of the stele has revealed that the speed was high in the order of body, pedestal and crown. Furthermore, to understand the present condition and occurrences of the cracks which have measured in many different forms on the stele quantitatively, we have estimated from 0.6 to 24.1㎝ deep of the cracks by To-Tc method using ultrasonic velocity.

Concrete is said to have a high degree of extensibility when it is subjected to large deformations without cracking. The cracking behavior of concrete in the field may even be more complex. For example, in mass concrete compressive stresses are developed during the very early period when temperatures are rising, and the tensile stresses do not develop until at a later age when the temperature begins to decline. Actual cracking and failure depend on the combination of factors and indeed it is rarely that a single adverse factor is responsible for cracking of concrete. The importance of cracking and the minimum width at which a crack is considered significant depend on the conditions of exposure of the concrete. The ultrasonic pulse measurements can be used to detect the development of cracks in structures such as dams, and to check deterioration due to frost or chemical action. An estimate of the depth of a crack visible at the surface can be obtained by measuring the transit times across the crack for two different arrangements of the transducers placed on the surface. In this paper, the concrete cracks that artificially introduced crack width is 1 and 2mm, crack depth is 2, 4, 6, 8cm were measured by Tc-To Method In consequence, the measured depth was increased with increase of measuring distance from concrete crack. The most reliable results were shown when the introduced crack width was 1mm, and the measuring distance was 10cm from concrete crack.