Prediksi nilai kuat tekan uniaksial batuan pengapit batubara menggunakan data ultrasonik di Kabupaten Musi Banyuasin Sumatera Selatan

Abstract

Support of geomechanics parameters is needed for gasifier design, analysis, and modeling on underground coalgasification (UCG) both from in-situ and laboratory test. One important of a laboratory test to evaluate of rockcondition at UCG location is uniaxial compressive strength test (UCS).This test needs the specific dimensionsample and also the sample that does not use for another laboratory test after testing such as for direct shear,triaxial or Brazilian test. To optimize the test, the sample should be chosen selectively. To get the sample by coredrilling is very difficult, time-consuming and costly. One way to optimize the use of samples is by usingcorrelation with another test that has the same output. This study has been conducted by the correlationbetween UCS and ultrasonic tests. UCS test is the destructive test and the ultrasonic test is non-destructive,relatively inexpensive, fast, easy to conduct and the samples can be re-used for another test. A total of 89ultrasonic and uniaxial compressive strength tests were conducted to establish three empirical correlation of UCSand a sonic velocity from the rocks flanking coal ( claystone, sandstone, and siltstone).This correlation can beused to predict the value of UCS empirically on research location at Macang Sakti, District of Musi Banyuasin,South Sumatra Province. The correlations resulted from the polynomial equation of ordo 2 and 3. To Claystoneσc value can be obtained from UCScls = (2 x 10-10)Vp3-(5 x 10-6)Vp2+ 0,0404Vp - 20,986 with R2 = 0.9087. Tosiltstone σc value can be obtained UCSsis = (3 x 10-6)Vp2+ 0,0051Vp + 9,8665 with R2 = 0.8953 and σcSandstone value can be obtained from UCSsas = -(7 x 10-7)Vp2 + 0,0467Vp - 41,484 with R2 = 0.8864.