Flyrock Analysis To Reduce The Safe Radius Of The Tools In Andesite Rock Blossing In The District Margaasih, Bandung Regency, West Java Province

Bandung regency known to have had to scatter material which be potential sources of revenue of them are material andesit mining sand and also .Research objectives is measuring the estimation of the distance the throw rocks due to maximum blasting , restudying in the determination of a radius of secure at blasting activities by counting the radius of safe to an instrument based on a theory that is compared with actual that had broken out and get constant k in signification fly rock according to alan b.richards and adrian j.moore to adjust to those of the rocks and stemming used .The research was done by counting the throw of maximum rock theoretically menutut alan b .Ricahrds and adrian j .Moore coupled with the observation actual fly rock in the field with the observation use video and the naked eye .Trial done by moving a radius of safe instrument less than 300 m. From the trial data, it is obtained that the maximum throw of the actual rock and the prediction with the theoretical calculation is in accordance with the recommendation of Adrian J. Moore and Alan B. Richard, so the radius to secure the tool is at least 2 times that of the actual throw. With the provision of using stemming, the safe radius for blasting is reduced to 200 m.

Estimation of Rock Burst Grades Using Rock Mass Strength

The traditional rock burst estimation method is usually based on the σc (rock strength) in practice, while the actual occurrence of rock burst depends more on the structure and strength of the rock mass. In this work, the actual rock bursts occurred in a railway tunnel project in Western China, and the σcm (rock mass strength) was calculated by the generalized Hoek–Brown criterion. According to the actual situation of rock bursts, a modified rock burst estimation criterion using the ratio of σcm to σmax (maximum geostress) was proposed. The influence of randomness on the reliability of rock burst estimation criterion was considered. The estimation results based on the traditional and modified method were furthermore compared with those of the actual rock bursts. The results show that σcm calculated by the generalized Hoek–Brown criterion may be considered well in the rock type and strength, construction condition, and structure features of the rock mass; the estimation results of rock burst using the ratio of σc to σmax are quite different from the actual situation, while those using the ratio of the σcm to σmax coincided relatively with the actual rock bursts; the ratios of σcm to σmax, which are greater than 0.167, 0.066 to 0.167, 0.012 to 0.066, and less than 0.012, are corresponded to the slight, medium, strong, and violent grades of the rock bursts, respectively; the randomness of data selection has certain influence on the rock burst estimation criterion, but the variation range is small; the modified estimation criterion of rock burst proposed in this work has a good reliability. The results presented herein are important for tunnel construction and the prevention of rock burst in the high geostress areas.

Analisis Kualitas dan Perkuatan Terowongan Eksplorasi Uranium Eko Remaja Kalan, Kalimantan Barat menggunakan Metode RMR (Rock Mass Rating)

ABSTRAK Terowongan Eksplorasi Uranium Eko Remaja Kalan (TEURK) di Kalimantan Barat yang dibangun pada tahun 1980 merupakan salah satu sarana penelitian cebakan uranium di Indonesia. Terowongan ini menembus Bukit Eko Remaja sepanjang 618 m, mulai dari pintu Remaja hingga TRK-7. Mineralisasi uranium di lokasi ini dikontrol oleh urat-urat tak beraturan (stockwork) yang sangat rapat pada batuan metalanau dan metapelit. Tingginya kerapatan struktur geologi tersebut membentuk beberapa zona lemah di dalam terowongan. Zona lemah tersebut berpotensi menyebabkan terjadinya longsor batu dan tanah. Penyangga sementara terbuat dari tiang-tiang kayu dipasang di zona tersebut untuk perkuatan terowongan. Saat ini tiang kayu tersebut tidak lagi mampu menyangga terowongan sehingga sering terjadi longsor batu dan tanah di dalam terowongan. Penelitian ini bertujuan untuk mengetahui kualitas massa batuan aktual dan menentukan jenis perkuatan yang sesuai agar terowongan tetap aman. Survei palu Schmidt dan scanline pada zona tak berpenyangga (kedalaman 50–297 m dan 355–538 m) dilakukan untuk mengambil data parameter klasifikasi Rock Mass Rating (RMR). Hasil pengukuran menunjukkan bahwa massa batuan TEURK di kedalaman tersebut memiliki nilai RMR 52-71 (sedang–baik). Perkuatan yang direkomendasikan adalah pemasangan baut batu dan beton semprot konvensional.ABSTRACT Tunnel for Exploration of Uranium Eko Remaja Kalan (TEURK) in West Kalimantan, built-in 1980, is one of the uranium deposit research facilities in Indonesia. The tunnel penetrated Eko Remaja Hill along 618 m, from Remaja to TRK-7 access. Uranium mineralization in this area controlled by dense stockwork veins on metasilt and metasandstone rocks. The high-dense geological structures create some weak zones in the tunnel. These zones are potentially causing rocks and soil slides. Temporary supports made of wood-piles were installed in these zones to support the tunnel. Currently, these piles are not capable at the tunnel, so that rocks and soil slides occurred inside the tunnel. The research aimed to determine the quality of actual rock mass and determine the appropriate type of reinforcement to keep the tunnel safe. Schmidt hammer and scanline surveys on the unsupported zone (50–297 m and 355–538 m depth) carried out to collect the classification parameter data of Rock Mass Rating (RMR). The measurement result shows that the rock mass of TEURK on the depth has an RMR value of 52–71 (fair-good). Reinforcement recommendations for the tunnel are rock bolts and conventional shotcretes installation.

The corresponding relationship between the change of goaf pressure and the key stratum breaking

Existing studies mostly focus on the stress change of coal in front of a goaf, but rarely conduct field monitoring on the internal pressure of a goaf, primarily due to the complex environment and other restrictive conditions of goafs. This paper first used physical simulation to monitor and analyze the internal pressure of goaf and found that goaf pressure presented a stepwise growth with the key stratum breaking. In addition, field measurements were conducted to monitor the goaf pressures of two different working faces. Goaf pressures both presented linear growth with the advance of the working face. According to comparative analysis, there were some differences between the two monitoring methods in terms of the corresponding relationship. This reflects that in the actual rock mass, after the breaking of a key stratum, the loads of the strata under its control are not transferred to the goaf instantaneously and load transfer characteristics are probably related to roof separation distribution characteristics of overlying strata, the bulking characteristics of caved rock mass, lateral stress limitation and other factors. The results of this study will offer some guidance for studies on the movement laws of overlying strata and the load transfer of overlying strata above goafs.

Quantifying influence of drilling additional boreholes on quality of geological model

Geotechnical stability analysis in open-pit mines requires access to a representative geotechnical model. The confidence level in the collected geotechnical data influences slope design. This paper investigates the influence of the number of boreholes, drilled to collect geological information, on the quality of one component of the geotechnical model, the geological model. The number of boreholes influences the number of rock core samples collected for the identification of rock type, and the definition of geotechnical domains and their boundaries within the rock mass. A challenge in the definition of the geotechnical domains is the determination of the drill hole density that minimizes the variation in the interpreted geological model from the actual rock mass. To quantify the influence of the drill hole density, boreholes are simulated in the most recently updated geological model for three mine sites. The simulated drill hole density is increased progressively until the variation of the interpreted section, compared with the original section, is minimized. A classification strategy was developed to determine the complexity level for each geotechnical domain. Furthermore, a series of empirical quantitative guidelines are presented prescribing the minimum drill hole density per domain complexity, while limiting variations from the actual rock mass.

Dynamic Response and Stability of Un-Reinforced and Reinforced Rock Slopes Against Planar Sliding Subjected to Ground Shaking

The authors have been performing some scaled model tests to investigate the response and stability of rock slopes against planar sliding. In these tests, rockbolts/rockanchors are modeled and their reinforcement effects on rock slopes against planar sliding during ground shaking are investigated. These model tests are also used to check the reliability of the numerical simulations. The authors present the outcomes of both model experiments and numerical simulations and compare their implications on actual rock slopes.

Comparison between Predicted Rock Mass Classes and Actual Rock Mass Classes in Headrace Tunnel of Upper Mai Hydroelectric Project, Nepal

This study involves comparison of predicted rock mass classes in design stage with actual rock mass classes of headrace tunnel of Upper Mai Hydroelectric Project. The total length of headrace tunnel is 2070.52 m. The lithology of the study area consists of gneiss, schistose gneiss and mica schist. The rock mass classifications, Q-system were used to predict rock mass classes during the design phase as well as for classify rock mass during excavation of headrace tunnel. The applicability and validity of proposed classification has been checked by comparing the prediction with actual observation after completion of excavation. It was found that the predicted classes does not exactly matches with the actual rock masses as a results effecting in construction time as well as in cost and economy of the project. HYDRO Nepal JournalJournal of Water Energy and EnvironmentIssue No: 22Page: 41-44Uploaded date: January 14, 2018