|Table of Contents|

Conversion relationship between uniaxial compressive strength and point load strength of sandy slate(PDF)

《交通运输工程学报》[ISSN:1671-1637/CN:61-1369/U]

Issue:
2022年04期
Page:
148-158
Research Field:
道路与铁道工程
Publishing date:

Info

Title:
Conversion relationship between uniaxial compressive strength and point load strength of sandy slate
Author(s):
CHEN Jian-xun CHEN Li-jun LUO Yan-bin XIE Jiang-tao WU Yun-fei LIU Wei-wei
(School of Highway, Chang'an University, Xi'an 710064, Shaanxi, China)
Keywords:
tunnel engineering sandy slate uniaxial compressive strength point load strength conversion relationship
PACS:
U452.12
DOI:
10.19818/j.cnki.1671-1637.2022.04.011
Abstract:
The sandy slate exposed in the excavation of the Muzhailing Tunnel of Weiyuan-Wudu Expressway in Gansu Province was taken as the object, and the uniaxial compressive strength test and point load strength test of sandy slate were carried out. The uniaxial compressive strength and point load strength of sandy slate as well as their conversion relationship were obtained through a normal distribution test, highly abnormal data elimination, and confidence interval strength statistic analysis of the test data. In addition, the conversion formulas were compared with those recommended by relevant codes for rock tests and the International Society for Rock Mechanics(ISRM). Research results show that the uniaxial compressive strength of saturated sandy slate obeys the normal distribution, with an average value of 56.3 MPa and a confidence interval of 49.2-63.5 MPa under a confidence level of 95%. The point load strength of saturated sandy slates is not completely consistent with the normal distribution, with an average value of 7.36 MPa and a confidence interval of 6.50-8.22 MPa under a confidence level of 95%. There is a significant linear positive correlation between the point load strength and uniaxial compressive strength of the saturated sandy slate. The rock strength is affected by the direction, filler, width, and length of internal joints and fissures of each specimen, and the overall discreteness of the strength data is high. The conversion coefficients between the uniaxial compressive strength and point load strength of sandy slate in saturated and dryed states are 7.72 and 8.72, respectively. They are obviously smaller than the conversion coefficient ranging from 15 to 30 in most studies. The reason is that there are bedding or joints and fissures with different angles in the sandy slate, and the uniaxial compressive strength is greatly affected by the internal joints and fissures of the specimen, resulting in a low average strength, while the point load strength is less affected by the internal joints and fissures of the specimen. The uniaxial compressive strength of sandy slate predicted by the formulas recommended by codes and ISRM is 2-4 times the measured value and will inevitably lead to large deviations in tunnel designs. In comparison with the formulas recommended by codes and ISRM, the obtained relative error of the conversion relationship between the uniaxial compressive strength and point load strength is not more than 15%. It can be used as a useful supplement to the formulas in codes. 8 tabs, 13 figs, 31 refs.

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Last Update: 2022-09-01