균질암반에서의 유압식 천공데이터 평가

김광염(Kwang-Yeom Kim),김창용(Chang-Yong Kim),김광식(Kwang-Sik Kim) 한국암반공학회 2008 터널과지하공간 Vol.18 No.6

천공탐사는 암반 굴착시 점보드릴의 유압착암기로부터 계측되는 기계량들인 천공데이터를 분석하여 암반의 특성을 평가하는 기법이다. 천공탐사는 발파공 또는 록볼트공 천공시 실시간으로 계측할 수 있기 때문에 암반을 신속하고 정량적으로 예측 및 평가할 수 있는 장점이 있다. 현재까지도 천공데이터에 관한 다양한 연구가 수행되어져오고 있지만, 암반 특성을 평가하기 위한 천공파라미터들의 항목 선정과 기계량들의 수치적인 정량화가 정립되어있지 않은 실정이다. 따라서 본 연구에서는 암석 및 지반 특성을 평가할 수 있는 천공파라미터의 항목 선정 및 천공시 천공데이터들 간의 관계를 파악하기 위해 균질 모형 암석 시험편을 제작하여 천공데이터를 획득하였고, 획득된 천공데이터를 이용하여 천공파라미터들의 상관관계 분석을 수행하였다. 분석 결과를 통해 유압착암기의 굴착능력은 타격에 의해 가장 큰 영향을 받음을 확인하였다. The drilling monitoring is a technique to assess rock mass properties by analyzing the mechanical quantities measured by drilling process. Since drilling survey can be conducted on real-time-basis for excavating blast holes or rockbolt holes, it may enables fast and quantitative prediction and evaluation of rock mass. Though a number of studies have been conducted on the drilling data, the selection of drilling parameters and numerical quantification of mechanical quantities or rock mass have not been well established yet. In this study, drilling tests were conducted with homogeneous rock specimen to identify drilling parameters and the relation of the drilling data. As a result, it is verified that above all drilling parameters, the percussion was the most important factor on the excavatability of hydraulic drilling.

RMR과 암석종류가 터널 천공속도에 미치는 영향

김해만,이인모,홍창호 사단법인 한국터널지하공간학회 2019 한국터널지하공간학회논문집 Vol.21 No.4

Drilling and charging of the blast holes during NATM tunneling works take more than 30% of construction time among the whole tunneling work process. Prediction of ground condition ahead of tunnel face has been studied by several researchers by correlating percussion pressure and drilling speed during tunneling work with the ground condition and/or RMR values. However, most of the previous researches were conducted in the granite rock condition which is the most representative igneous rock in the Korean peninsula. In this study, drilling speeds in igneous rocks were analyzed and compared with those in sedimentary rocks (most dominantly composed of conglomerates, sandstones, and shales) under the similar RMR ranges; it was identified that the drilling speed is pretty much affected by rock types even in a similar RMR range. Under the similar RMR values, the drilling speed was faster in sedimentary rocks compared with that in igneous rock. Moreover, while the drilling speed was not much affected by change of the RMR values in igneous rocks, it became faster in sedimentary rocks as the RMR values got lower. NATM 공법을 이용한 터널굴착 시 발파공 천공 및 장약 작업은 전체 터널 굴착 시간의30% 이상을 차지하는 중요한 과정이다. 최근에는 이 공정을 활용하여 천공작업 도중 얻어지는 타격압, 천공속도 등을 바탕으로 터널 굴착면 전방의 지반상태, RMR 등을 예측하는 연구들이 진행되어 왔다. 하지만 선행 연구들은 대부분 화강암으로 대표되는 화성암질 지반에 대해서만 수행되어왔다. 본 연구에서는 유사한 RMR의 범위를 가지는 화성암의 천공속도를 퇴적암(특히, 역암, 사암 및 셰일)의 천공속도와 비교/분석하였으며, 유사한 RMR 값을 가지는 암이라 하더라도 암질 종류에 따라서 천공속도가 크게 달라질 수 있음을 확인하였다. 퇴적암에서의 천공속도가 화성암에서의 속도보다 더 빨랐으며, 또한 화성암의 경우 천공속도와 RMR등급에 따른 천공속도의 차이는 거의 없는 것에 반하여, 퇴적암의 경우는 RMR등급이 낮아질수록 천공속도는 증가함을 알수 있었다.

Evaluation of Drilling Efficiency by Percussion Testing of a Drill Bit with New Button Arrangement

Kwon, Ki-Beom,Song, Chang-Heon,Park, Jin-Young,Oh, Joo-Young,Lee, Jae-Wook,Cho, Jung-Woo 한국정밀공학회 2014 International Journal of Precision Engineering and Vol.15 No.6

Rock drilling machines are commonly used for surface drilling, soil nailing reinforcement, tunnel excavation, and underground mining. These machines use drill bits that directly impact into the rock and are operated by percussive force and torque. Drill-bit buttons need to be designed to increase drilling efficiency; here, we present the results of a series of single blow tests on granitic rock samples using a piston drop type percussion testing system that enable us to compare the drilling efficiency of a new button arrangement design with conventional arrangements. Drilled rock volumes were measured by laser scanner after testing, and drilling efficiencies were evaluated by calculating percussive energies and drilled volumes. The results indicate that the new button arrangement design can be used to improve the drilling efficiency.

GSI를 이용한 암반에 근입된 현장타설말뚝의 주면저항력 산정

조천환(Cho Chun Whan),이혁진(Lee Hyuk Jin) 대한토목학회 2006 대한토목학회논문집 C Vol.26 No.1

대부분의 설계지침서에서는 암반에 근입된 현장타설말뚝의 주면저항력을 산출하기 위하여 암석의 일축압축강도를 사용한다. 그러나 최근에 도로교 설계기준 해설(대한토목학회, 2001)과 AASHTO 설계지침서(2000)에서는 현장조건을 보다 잘 반영할 수 있도록 RQD를 적용하여 산출한 암반의 일축압축강도를 사용하도록 개정되었다. 그런데 RQD를 이용하여 암반의 일축압축강도를 산정하는 식을 국내의 주요 기반암에 적용하는 데에 문제가 제기되었고, 여기에는 RQD 자체의 문제점, 즉 지하수, 절리면 상태 등을 반영하지 못한다는 점도 포함되었다. 결국 도로교 설계기준 해설(2001)은 암석의 일축압축강도를 이용하여 주변저항력을 산정하는 방법으로 다시 개정되었다(한국도로공사, 2002). 본 연구에서는 암석의 일축압축강도와 현장 암반의 일축압축강도를 연관시키는 수단으로 제시되어 있는 기존의 여러 방법을 비교ㆍ검토하였으며, 이 가운데 신뢰도가 있는 것으로 평가되고 있는 Hoek-Brown 파괴 규준을 이용하여 암반의 일축압축강도 추정식을 제시하였다. 또한 이를 이용하여 암반에 근입된 현장타설말뚝의 주면저항력 예측 방법을 제안하였다. 제안된 방법은 현장타설말뚝의 재하시험 데이터를 이용하여 기존의 여러 방법으로 구한 주면저항력과 비교한 결과 신뢰도가 있음을 알 수 있었다. It is common to use the unconfined compressive strength (UCS) of intact rock to estimate the shaft resistance of rock socketed drilled shaft. Therefore the most design manuals give a guide to use the UCS of rock core to estimate the shaft resistance of rock-socketed drilled shaft. Recently, however the design manuals for highway bridge (KSCE, 2001) and of AASHTO (2000) were revised to use the DCS of rock mass with RQD instead of the UCS of rock core so that the estimated resistance could be representative of field conditions. Questions have been raised in application of the new guide to the domestic main bed rock types. The intrinsic drawbacks in terms of RQD were comprised in the questions, too. As the results, in 2002 the new guide in the design manual for highway bridge (KSCE, 2001) were again revised to use the UCS of rock core to estimate the shaft resistance of rock-socketed drilled shafts. In this paper, various methods which can estimate the UCS of rock mass from intact rock core were reviewed. It seems that among those, the Hoek-Brown method is very reliable and practical for the estimation of the UCS of rock mass from rock cores. As the results, using the Hoek-Brown failure criterion a modified guide for the estimation of the shaft resistance of rock-socketed drilled shafts was suggested in this paper. Through a case study it is shown that the suggested method gives a good agreement with the measured data.

Development of Lab-Scale Rock Drill Apparatus for Testing Performance of a Drill Bit

Song, Chang-Heon,Kwon, Ki-Beom,Cho, Min-Gi,Oh, Joo-Young,Shin, Dae-Young,Cho, Jung-Woo Korean Society for Precision Engineering 2015 International Journal of Precision Engineering and Vol.16 No.7

This study experimentally validated the reliability of the lab-scale rock drill apparatus and investigated the effect of bit design factors on the performance of drilling. To test drilling efficiency of a drill bit, a testing system was designed and manufactured. Using the testing system, the drilling rates and specific energy of a conventional drill bit and newly proposed drill bit with different button arrangement were compared. The newly proposed model was tested to be superior in drilling performance than that of the conventional model. The testing system developed in this study could be used to predict and test the performance of newly developed drill bit models. Also, the system has to be improved further for measuring more accurate and quantitative data for future drill bit developments.

Development of Lab-Scale Rock Drill Apparatus for Testing Performance of a Drill Bit

송창헌,권기범,조민기,오주영,신대영,조정우 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.

This study experimentally validated the reliability of the lab-scale rock drill apparatus and investigated the effect of bit design factors on the performance of drilling. To test drilling efficiency of a drill bit, a testing system was designed and manufactured. Using the testing system, the drilling rates and specific energy of a conventional drill bit and newly proposed drill bit with different button arrangement were compared. The newly proposed model was tested to be superior in drilling performance than that of the conventional model. The testing system developed in this study could be used to predict and test the performance of newly developed drill bit models. Also, the system has to be improved further for measuring more accurate and quantitative data for future drill bit developments.

Modeling and Performance Analysis of Rock Drill Drifters for Rock Stiffness

오주영,이근호,강학순,송창섭 한국정밀공학회 2012 International Journal of Precision Engineering and Vol. No.

Rock drill operations are classified as top hammer drilling (THD), down-the-hole drilling, or rotary drilling. The rock drill in the THD method consists of a percussion drill rig module and a drill bit. The percussion drill rig module consists of a drifter, feed drive, and auto rod changer. In particular, the drifter generates the impact and rotational force for drilling. The purpose of this study was to analyze the hydraulic circuits of the drifter and to develop an analysis tool for analyzing the impact capability. This study also analyzed the capability of the drifter with regard to the penetration rate and varying kinetic energy, which is dependent on rock stiffness, using the developed analysis tool.

Evaluation of Drilling Efficiency by Percussion Testing of a Drill Bit with New Button Arrangement

권기범,조정우,송창헌,박진영,오주영,이재욱 한국정밀공학회 2014 International Journal of Precision Engineering and Vol. No.

Rock drilling machines are commonly used for surface drilling, soil nailing reinforcement, tunnel excavation, and undergroundmining. These machines use drill bits that directly impact into the rock and are operated by percussive force and torque. Drill-bitbuttons need to be designed to increase drilling efficiency; here, we present the results of a series of single blow tests on granitic rocksamples using a piston drop type percussion testing system that enable us to compare the drilling efficiency of a new buttonarrangement design with conventional arrangements. Drilled rock volumes were measured by laser scanner after testing, and drillingefficiencies were evaluated by calculating percussive energies and drilled volumes. The results indicate that the new buttonarrangement design can be used to improve the drilling efficiency.

Development of Static Rock Penetrometer for Locating Rock Stratum During Construction of Drilled Shafts

남문석 한국지반공학회 2010 한국지반공학회논문집 Vol.26 No.9

During construction of deep foundation in soft rock under varying soil properties, it is essential to locate the rock stratum, especially when drilling with slurry. When slurry is used for drilling, the bottom of the borehole cannot be seen, thereafter soil cuttings cannot be differentiated from soft rock cuttings. A new static rock penetrometer, known as Rock Penetrometer was developed during this study. It could be a simple mechanical device that is attached to the bottom of a Kelly bar which is used to attach drilling tools such as augers and core barrels while drilling. After its calibration in the laboratory, the performance of the static rock penetrometer was verified in the several field test sites.

Rock-breaking analysis model of new drill bit with tornado-like bottomhole model

Jia-lin Tian,Chang-fu Yuan,Lin Yang,Chuan-hong Fu,Gang Liu,Zhi Yang,Chun-ming Wu 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.4

For improving the rock-breaking efficiency of oil and gas drill bits, a new drill bit is presented with tornado-like bottomhole model(named swirling cutting bit). The new drill bit cutter breaks rock with shocking and cutting effect during the drilling process, and theelements on largest ring cross the borehole center with high speed. It can effectively improve the center rock-breaking efficiency. Meanwhile,for all cutters on different rings breaking rock at the same time, it can optimize the rock-breaking volume of each element andimprove the bit service life. To analyze the interaction features between cutters and rock, the position equations are established by thecylindrical coordinates and complex movement principles, and then the velocity and acceleration equations can be obtained. Based on thenumerical example results, this paper analyzes the bottomhole model, the contact section, and the distribution features of velocities andaccelerations on different rings. By analyzing the acceleration results, we can study the failure mechanism of cutters. At the same time,lab experiments test the bottomhole model and rock-breaking features, and it verifies the accuracy of calculation method and equations. Moreover, the analysis method and models are also applicable to other types of bits or composite bits, and the inputting parameters needcorresponding adjustment for different type of bits.