Multielement biogeochemistry and lithium isotopic composition of the dominant plants at the Jiajika mine, western Sichuan, China - The largest hard rock-type lithium mine in Asia

Uniaxial compressive strength (UCS) is a very important fundamental mechanical parameter for TBM construction. In this work, a predictive model of UCS was proposed according to the TBM parameters including torque, penetration, cutter number, and cutter diameter. The parameter of the new proposed model was established by fourteen existed TBM tunnels’ construction data. To describe the relationships of UCS with PLSI of the Murree tertiary hard rocks, regression analyses have been conducted and a fitting equation with high-prediction performance was developed. Validation from the data of Neelum–Jhelum (NJ) TBM diversion tunnel were carried out. The absolute errors between predictive UCS and experimental UCS were presented. Through comparison, it can be concluded that the proposed calculation equation of UCS has a high accuracy for a certain rock type with UCS from 50 MPa to 200 MPa. For special hard rock or soft rock, a new calculation equation between UCS and TBM parameters should be studied furthermore.

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Assured Stability of Drillstrings Equipped With Polycrystalline Diamond Compact (PDC) Bits

Volume 5: 19th Biennial Conference on Mechanical Vibration and Noise, Parts A, B, and C ◽

10.1115/detc2003/vib-48620 ◽

2003 ◽

Cited By ~ 1

Author(s):

M. A. Elsayed

Keyword(s):

Stability Analysis ◽

Geothermal Energy ◽

Hard Rock ◽

Rock Type ◽

Polycrystalline Diamond ◽

Deep Wells ◽

Drilling Parameters ◽

Pipe Joints ◽

Polycrystalline Diamond Compact ◽

Oil Gas

Drillstrings equipped with PDC bits are commonly used to drill for oil, gas and geothermal energy. Drillstring instability — defined as the tendency of self-excited vibrations (chatter) to grow with time — causes failure of PDC bits as well as pipe joints. This problem becomes particularly severe in deep wells and hard rock. Much work has been performed in predicting stability. Bit and drillstring geometry as well as rock type affect stability. In this paper, we propose a scheme to assure stability for a given drillstring regardless of bit geometry, utilizing the desired drilling parameters. The effect of bit geometry and rock type in the classic stability analysis are replaced by the drilling parameters, namely: weight-ob-bit (WOB), rate of penetration (ROP) and speed (RPM). Experimental data obtained at Sandia National Labs, Albuquerque, N.M. is used to verify the assured stability equation. This approach is much simpler that classic stability analysis.

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Development of New PDC Bits for Drilling of Geothermal Wells—Part 1: Laboratory Testing

Journal of Energy Resources Technology ◽

10.1115/1.2905960 ◽

1992 ◽

Vol 114 (4) ◽

pp. 323-331 ◽

Cited By ~ 5

Author(s):

H. Karasawa ◽

S. Misawa

Keyword(s):

Hard Rock ◽

Rock Type ◽

Penetration Rate ◽

Polycrystalline Diamond ◽

Rock Cutting ◽

Rake Angle ◽

Well Drilling ◽

Pdc Bit ◽

Geothermal Wells ◽

Polycrystalline Diamond Compact

Rock cutting, drilling and durability tests were conducted in order to obtain data to design polycrystalline diamond compact (PDC) bits for geothermal well drilling. Both conventional and new PDC bits with different rake angles were tested. The rock cutting tests revealed that cutting forces were minimized at −10 deg rake angle independent of rock type. In drilling and durability tests, a bit with backrake and siderake angles of −10 or −15 deg showed better performance concerning the penetration rate and the cutter strength. The new PDC bit exhibited better performance as compared to the conventional one, especially in hard rock drilling. Furthermore, a new PDC core bit (98.4 mm o. d., 66 mm i. d.) with eight cutters could be successfully applied to granite drilling equally as well as a bit with twelve cutters.

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Correction to "Characterization and isotopic composition of organic and inorganic carbon in the Milk River aquifer" (WRR 25(8), 1893-1905, August 1989)

Water Resources Research ◽

10.1029/89wr03205 ◽

1990 ◽

Vol 26 (1) ◽

pp. 167-167

Author(s):

Ellyn M. Murphy

Keyword(s):

Isotopic Composition ◽

Inorganic Carbon ◽

Organic And Inorganic Carbon ◽

Milk River Aquifer

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Reconstruction of maximum temperature on Zhegu Mountain, western Sichuan Plateau (China)

Climate Research ◽

10.3354/cr01606 ◽

2020 ◽

Vol 81 ◽

pp. 1-14

Author(s):

M Keyimu ◽

Z Li ◽

Y Zhao ◽

Y Dong ◽

B Fu ◽

...

Keyword(s):

Tree Growth ◽

Ring Width ◽

Volcanic Eruptions ◽

Southwestern China ◽

Maximum Temperature ◽

Driving Mechanism ◽

Western Sichuan ◽

Relationship Analysis ◽

Decadal Scale ◽

Thermal Variability

Historical temperature reconstructions at high altitudes are still insufficient in southwestern China, which is considered one of the most sensitive areas to climate change in the world. Here we developed a tree ring-width chronology of Faxon fir Abies fargesii var. faxoniana at the upper timber line on Zhegu Mountain, Miyaluo Scenic Area, western Sichuan, China. The climate-tree growth relationship analysis indicated temperature as the dominant regulator on radial tree growth in this region. The reconstruction of aggregated maximum temperature (TMX) of autumn and winter for the period 1856-2016 was achieved with a linear regression model that accounted for 43.6% of the actual variability in the common time series (1954-2016). The reconstruction identified 4 warm periods and 3 cold periods. Similarities of warm and cold periods with previously published reconstructions from nearby sites indicated the reliability of our reconstruction. The significant positive correlation between TMX reconstruction and the Asian-Pacific Oscillation index and the Atlantic Multi-decadal Oscillation index suggested a linkage between large-scale climate circulations and the thermal variability at a multi-decadal scale on the western Sichuan Plateau. We also found that solar activity exerted a strong influence on decadal temperature variability in this region. The cold periods were matched well with historical large volcanic eruptions. Our results strengthen the historical climatic information in southwestern China and contribute to further understanding the regional thermal variability as well as its driving mechanism.

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