Prediction of end-bearing capacity of rock-socketed shafts considering rock quality designation (RQD)

2010 ◽  
Vol 47 (10) ◽  
pp. 1071-1084 ◽  
Author(s):  
Lianyang Zhang

Existing empirical methods for determining the end-bearing capacity, qmax, use empirical relations between qmax and the unconfined compressive strength of intact rock, σc. As rock-socketed shafts are supported by the rock mass, not just the intact rock, one should consider not only the intact rock properties, but also the influence of discontinuities on rock mass properties when determining qmax. Although semi-empirical and analytical methods have been developed that can consider the effect of discontinuities, they are more complicated than the empirical relations and require information about discontinuities that is often not available or difficult to obtain in engineering practice. In this paper, an empirical relation between qmax and the unconfined compressive strength of rock mass, σcm, is developed. The new empirical relation explicitly considers the effect of discontinuities represented by rock quality designation (RQD), which is the parameter normally obtained in engineering practice. The accuracy of the expression for estimating σcm based on RQD is verified by comparing its estimation values with those from the existing empirical expressions based on rock mass classification. Two examples are presented to show the application of the newly developed empirical relation between qmax and σcm.

EKSPLORIUM ◽  
2015 ◽  
Vol 36 (1) ◽  
pp. 17 ◽  
Author(s):  
Heri Syaeful ◽  
Dhatu Kamajati

Karakterisasi massa batuan diperlukan dalam suatu rancangan bukaan batuan, dimana perhitungan sifat-sifat teknis dari massa batuan menjadi hal yang penting untuk diperhatikan. Sektor Lemajung merupakan salah satu area prospek untuk penambangan uranium di Kalan, Kalimantan Barat. Tujuan penelitian adalah mendapatkan data karakteristik massa batuan yang merupakan data dasar bagi perencanaan pengembangan teknik penambangan cebakan bahan galian. Metodologi yang digunakan adalah dengan pengambilan contoh batuan untuk analisis laboratorium mekanika batuan, pengamatan rekahan, dan pengamatan kondisi airtanah. Parameter batuan yang dianalisis meliputi uniaxial compressive strength (UCS), rock quality designation (RQD), jarak rekahan, kondisi rekahan, dan airtanah. Hasil analisis menyimpulkan bahwa metalanau sebagai litologi yang mengandung uranium di Sektor Lemajung mempunyai nilai rock mass rating (RMR) sebesar 56 atau kelas massa batuan III: fair rock pada kedalaman sekitar 60 m, dan pada kedalaman 280 m nilai RMR mencapai 82 atau kelas massa batuan I: very good rock. Data nilai RMR tersebut selanjutnya dapat digunakan dalam analisis pembuatan terowongan pada model tambang bawah tanah atau analisis kestabilan lereng pada model tambang terbuka. Rock mass characterization is required in design of rock opening, which calculation of engineering characters of rock mass become one important parameter toconsider. Lemajung sector is one of prospect area for uranium mining in Kalan, West Kalimantan. Purpose of research is to acquire rock mass characteristicsas basic data for planning the development of mining technique of ore deposit. Methodology applied is rock sampling for rock mechanic laboratory analysis, observation of joints, and observation of groundwater condition. Rock parameters analyzed includes uniaxial compressive strength (UCS), rock quality designation (RQD), joint spacing, joint condition, and groundwater. Analysis concluded that metasiltstonewhich is lithology contained uranium in Lemajung Sector has rock mass rating (RMR) value of 56 or rock mass class III: fair rock in the depth of around 60 m, and in the depth of 280 m RMR value reach 82 or rock mass class I: very good rock. RMR value data furthermore could be used for analysis of tunneling in the model of underground mine or slope stability analysis in the model of open pit mine.


2000 ◽  
Vol 22 ◽  
Author(s):  
Cristian Marunteanu ◽  
Ion Durdun

A model of engineering geological classification and zoning of the Scorillo Dam site in Romania is proposed to optimise the design of the dam and of the grout curtain. The rock mass was classified into four categories: from 1 (good) to 4 (very poor), according to the rock mass quality (RMQ) at the dam site. Parameters available and used to determine the RMQ were lithology, degree of weathering and fragmentation, rock quality designation (RQD), and modulus of elasticity (E). Based on the study, a new design of the dam, its slopes, and the grout curtain was carried out.


2018 ◽  
Vol 1 (3) ◽  
pp. 647-656
Author(s):  
Jumaidi Jumaidi ◽  
Munirwansyah Munirwansyah ◽  
Sofyan M. Saleh

Abstract: The Tapaktuan-Bakongan is the national road access to the South-West part of Aceh. Topographically shows that the road consist of canyon and a very steep cliff, which will be impossible to build more infracstructure using either blasting or cut and fill method with heavy equipment. Referring to the situation, the study about anchor tensile strength, which is used in construction of road access expansion using cantilever method is conducted. The research methode is begin by collecting the real data which are Standard Penetration Test data (SPT) SNI 4153-2018 and tensile graund anchor proving test (Bristish Satndard 8081:1981) and geological data taken from SPT drilling data. Furthermore, the data involved N-SPT, Joint Roughness Coefficient (JRC), shear stress will be analyzed and yield loading test value. Finally, from the loading test value, the reseacher will evaluate the stability of tensile capacity and safety factor (SF) of ground anchor. From the data analysis obtained that rock mass of STA 1+ 280 or KM. 461 +480 geologically contain unrigid and very strong limestone with N-SPT value greater than 50 where the rock condition is solid concrete and could be crushed using blasting method. Five samples are taken from the 10 meters driling for the laboratory test and obtain the minimum compressive strength is 51,10 MPa and maximum is 103,89 MPa with JRC from 2 to 20. In addition, the rock quality designation (RQD) calculation yield the average stone quality is 60,8% which means the rock has medium quality. Ground anchor failure if the proving test over 80% UTS(ultimate tensile strength)   i.e. the load increment reaches 92,55% UTS or 54 MPa. Therefore, the proving test maximum capacity for ground anchor is 54 Mpa and safety factor is 1,85 which are suitable to geological condition research area.Abstrak: Ruas jalan Tapaktuan – Bakongan merupakan ruas jalan nasional lintas Barat – Selatan Aceh. Kondisi topografi ruas jalan terdiri dari tebing yang terjal dan lereng yang curam sehingga tidak memungkinkan dilaksanakan pelaksanaan kontruksi pembangunan/peningkatan dengan metode blasting (penggunaan bahan peledak) maupun metode cut and fill yang menggunakan alat-alat berat. Dari permasalahan tersebut dilakukan sebuah kajian mengenai kuat tarik angker yang digunakan pada pelaksanaan pembangunan pelebaran badan jalan dengan menggunakan metode kantilever untuk daerah dengan kondisi topograsi tebing yang terjal dan lereng yang curam. Metode yang diterapkan pada penelitian ini diawali dengan pengumpulan data riil yang meliputi data Standard Penetration Test (SPT) SNI 4153-2008 dan uji tarik proving test ground anchor (British Standard 8081:1981) dan data geologi yang dihasilkan dari data pengeboran SPT. Selanjutnya dari data-data yang diperoleh dilakukan analisis data yang meliputi analisis nilai N-SPT, Joint Roughnes Coefficient (JRC), gaya geser, yang menghasilkan angka loading test. Dari data hasil loading test dapat dievaluasi stabilitas kapasitas tarik dan safety factor (SF). Dari data analisis didapatkan bahwasanya kondisi geologi batuan di STA 1+ 280 atau KM. 461 + 480 terdiri dari batu gamping tidak lapuk dan sangat keras dan dapat dipecahkan dengan peledakan dengan nilai N-SPT lebih besar dari 50 dimana kondisi batuan sangat padat. Dari hasil pengeboran sepanjang 10 meter diambil lima sampel untuk di uji laboratorium dan diperoleh nilai compressive strength minimal 51,10 MPa dan maksimum 103,89 MPa dengan nilai JRC 2-20. Selain daripada itu hasil perhitungan rock quality designation (RQD) menunjukkan kualitas batuan pada lokasi kajian rata-rata 60,8% yang berarti kualitas batuannya adalah sedang. Ground anchor putus pada saat uji tarik proving test diatas pembebanan 80% UTS yaitu pembebanan sampai 92,55% UTS (ultimate tensile strength) atau sebesar 54 MPa. Dengan demikian kapasitas maksimum hasil uji tarik proving test ground anchor yaitu sebesar 54 MPa dengan faktor keamanan 1,85 sesuai dengan kondisi geologi daerah kajian.


2019 ◽  
Vol 3 (2) ◽  
pp. 11
Author(s):  
Ainul Fatayaatis Salaamah ◽  
Teuku Faisal Fathani ◽  
Wahyu Wilopo

One important part of rock mass investigation is the geomechanical assessment in terms of rock mass classification systems. Rock mass classification is one of themost efficient methods in rock mechanics to provide a basic understanding of rock masscharacterization. Rock mass properties can be determined by a seismic refraction surveyas an indirect geophysical assessment. In this study, the P-wave velocity from seismicrefraction was compared with the Rock Quality Designation (RQD) from the boreholes.The empirical correlation between the RQD and the P-wave velocity was found by usingthe linear regression analysis. The RQD value estimated from the P-wave velocity can beapplied for tropical environment study with geological conditions of volcanic rocks. This study helps to estimate and predict the subsurface rock quality, to reduce investigation costs, and to improve understanding of subsurface rock quality.


2019 ◽  
Vol 42 ◽  
pp. e44764
Author(s):  
Gissele Souza Rocha ◽  
Claudio Henrique de Carvalho Silva ◽  
Heraldo Nunes Pitanga ◽  
Ecidinéia Pinto Soares de Mendonça ◽  
Dario Cardoso de Lima ◽  
...  

The main objective of this study was to propose the application of soil-lime mixtures asa primary coating layerof unpavedforestroads based on the premise that this layer can be considered mechanically similar to a flexible pavementsub base layer, aiming to fill a gap in the current technical literature and engineering practice in this field of knowledge. In the study, a laboratory test program was carried out in a residual gneiss soil encompassing: (i) geotechnical characterization tests; (ii) compaction tests at the standard Proctor energy on soil specimens and on soil-lime mixturespecimens prepared with lime contents of 2, 4 and 6% related to the dry soil mass; (iii) unconfined compressive strength tests on soil specimens compacted at the standard Proctor optimum parameters; and (iv) unconfined compressive strength tests on specimens of soil-lime mixtures compacted at the standard Proctor optimum compaction parameters with lime contents of 2, 4 and 6%, and cured at 22.8°C in the curing periods of 3, 7, 28 and 90 days. The results showed that the addition of lime resulted in: (i) reduction in soil maximum dry unit weight (gdmax) and increase in soil optimum water content (wopt);and(ii) significant gains in soil unconfined compressive strength that evidenced the expressive occurrence of pozzolanic reactions in the mixtures.Based on the hypothesis of a similar requirement for soil-cement and soil-lime mixtures, the tested soil-lime mixtures met the minimum mechanical strength (1.2MPa) required for application as a primary coating layer of unpaved forest roads.


2020 ◽  
Vol 5 (1) ◽  
pp. 35-48
Author(s):  
Абдулхалим Зарьяб ◽  
◽  
Мохаммад Ибрагим Наджаф ◽  
Мохаммад Зия Джамал

В настоящее время на реке Шакардара примерно в 22 км к северо-западу от г. Кабул, Афганистан, ведется строительство плотины Шах-и-Арус. Ее высота и длина составляют 77,5 м и 303 м, соответственно, а объем водохранилища оценивается примерно в 9,38 млн м 3 . Данное многоцелевое сооружение возводится из роликового уплотненного бетона (RCC) и предназначено для хранения оросительной воды, сдерживания наводнений и выработки электроэнергии. Плотина располагается в тектонически активной зоне, чем обусловливается значительное воздействие на нее тектонических процессов. В настоящей статье представлены результаты сопоставления показателей нарушенности горных пород (Rock Quality Designation, RQD) и параметров Люжона, основанных на обзоре и анализе материалов первоначальных инженерно-геологических изысканий и дополнительных полевых наблюдений. Результаты значений Люжона и показателей RQD прошли статистически-графическую оценку, и далее данные полученных графиков были сопоставлены со всеми другими естественными условиями зоны строительства плотины. Полученные результаты указывают на то, что комплекс природных условий в определенной степени характеризуется взаимосвязью между значениями Люжона и параметрами RQD. Кроме этого, массив горных пород основания плотины был охарактеризован в соответствии с классификацией скальной породы RMR (Rock Mass Rating).


2015 ◽  
Vol 52 (10) ◽  
pp. 1466-1476 ◽  
Author(s):  
M. Vavro ◽  
K. Souček ◽  
L. Staš ◽  
P. Waclawik ◽  
L. Vavro ◽  
...  

A comparison of rock quality designation (RQD) parameters obtained by drill core analysis and the RQD determined using alternative methods is presented using metamorphic rocks such as migmatized gneisses, migmatites, and amphibolites. Methods of borehole–wall imaging using high-resolution acoustic logging, optical televiewer, and simple video inspection as well as the structural analysis of exploration drift walls oriented subparallel to the analysed boreholes are used for alternatively evaluated RQD values. Results show that, in most cases, the RQD index measured directly on a drill core section reaches lower values (about 10%–30%) than the RQD evaluated by alternative methods. Significant differences in determination of the rock mass failure degree using classical and alternative methods may occur, especially in sections with higher frequency of the metamorphic foliation planes created by biotite-rich bands or by dark-coloured melanosome layers. The nature of biotite itself is favourable for the creation of pre-disposed jointing planes, in which the increased drill core disintegration caused by drilling technology or core handling can occur. Results show it is highly appropriate to make these comparisons on a larger scale and thus verify whether the observed differences affect the qualitative classification of the rock mass.


2014 ◽  
Vol 59 (2) ◽  
pp. 517-528
Author(s):  
Robert Duda

Abstract Methods of determining the depth of rock mass freezing for the purpose of shaft sinking in solid rocks in difficult hydrogeological and geomechanical conditions are analyzed in this paper. There are presented factors on the basis of which the freezing depth can be determined in heterogeneous rocks media. The author focuses on the source of problems with establishing parameters used for defining the freezing depth. A method of interpreting hydrogeological and geomechanical source data is presented on two examples of weak and medium compact sandstones freezing for the purpose of shaft sinking in the Legnica-Głogów Copper Mining District, south-western Poland. Moreover, a general algorithm for determining the rock mass freezing depth is given. The following main criteria of freezing depth evaluation have been assumed: hydraulic conductivity values, porosity, rock quality designation index (RQD) and Protodiakonow’s rock compaction index. The outflow of drilling fluid in the exploration borehole was taken into account as a complementary criterion. The practical use of the algorithm was exemplified by a geological profile.


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