GB/T 50266-2013 in English

1 General Provisions

1.0.1 This standard is formulated to unify the test methods of engineering rorck mass, improve the test results quality and strengthen the comparability of test results.
1.0.2 This standard is applicable to engineering rock mass tests for foundation soil, surrounding rock, side slope and filling materials.
1.0.3 Engineering rock mass test objects shall represent the geology. The test content, test methods and technical conditions shall meet the basic requirements and characteristics of the engineering construction survey, design, construction and quality inspection.
1.0.4 The engineering rock mass test shall not only comply with this standard but also comply with those in the current relevant ones of the nation.

2 Laboratory Rock Tests

2.1 Water Content Test

2.1.1 Drying method shall be used for all rock water content tests.
2.1.2 Rock specimens shall meet the following requirements:
1 If the sample remains the natural moisture content, it shall be sampled on site by methods rather than blasting. The sample shall remain the natural moisture condition during the sampling, transport, storage and specimen preparation. When the water content is required to be tested in other tests, the specimen may be used for preparation after the test.
2 The minimum size of specimen shall be larger than 10 times the diameter of largest mineral grain forming the rock; the mass of each specimen is 40g~200g and 5 specimens are used in each group of test.
3 The determination of water content of the structural surface fillings shall meet the requirements of the current national standard GB/T 50123 "Methods for Geotechnical Test".
2.1.3 The specimen description shall cover the following information:
1 Rock name, color, mineralogical composition, structure, construction, degree of weathering, agglutinate property, etc.
2 The measures taken to keep the moisture condition.
2.1.4 The following apparatus shall be included:
1 Dry oven and dryer.
2 Balance.
2.1.5 The test shall be carried out according to the following procedure:
1 The mass of specimen shall be weighed before drying.
2 The specimen shall be put in the dry oven and dried at 105~110℃ for 24h.
3 The specimen is taken out of the dry oven, put into the dryer for cooling to the room temperature and the dried mass shall be weighted.
4 Weighing shall be accurate to 0.01g.
2.1.6 The test results shall be processed in accordance with the following requirements:
1 Rock water content shall be calculated according to the following formula:
(2.1.6)
Where,
ω——the rock water content (%);
m0——the specimen mass before the drying (g);
ms——the mass of specimen after the drying (g).
2 The calculated values shall be accurate to 0.01.
2.1.7 Rock water content test records shall include project name, specimen numbers., specimen description and the specimen mass before and after drying.

2.2 Grain Density Test

2.2.1 The rock grain density test shall adopt Pyknometer method or inwater weight method. The former may be used for all rocks but the latter shall comply with 2.4 of this standard.
2.2.2 Production of rock specimens shall meet the following requirements:
1 The rock shall be crushed into rock dust with a grinder to make all dust pass a 0.25mm sieve mesh and the scrap iron shall be absorbed by a magnet.

Foreword I
1 General Provisions
2 Laboratory Rock Tests
2.1 Water Content Test
2.2 Grain Density Test
2.3 Bulk Density Test
2.4 Water Absorption Test
2.5 Swelling Test
2.6 Slaking Test
2.7 Uniaxial Compressive Strength Test
2.8 Freezing-thawing Test
2.9 Uniaxial Compressive Deformability Test
2.10 Triaxial Compressive Strength Test
2.11 Tensile Strength Test
2.12 Direct Shear Strength Test
2.13 Point-load Strength Test
3 Deformability Tests of Rock Mass
3.1 Method of Bearing Plate
3.2 Borehole Radial Loading Test
4 Strength Test of Rock Mass
4.1 Direct Shear Test for Concrete-Rock Contact Surface
4.2 Direct Shear Test for Rock Mass Discontinuities
4.3 Direct Shear Test for Rock Mass
4.4 Load Test of Rock Mass
5 Rock Sonic Testing
5.1 Sound Velocity Testing of Rock Specimens
5.2 Sound Velocity Testing of Rock Mass
6 Rock Stress Testing
6.1 Testing Using Shallow Borehole-wall Strain Gauge
6.2 Testing Using Shallow Borehole Radial Deformation Meter
6.3 Testing Using Shallow Borehole-bottom Strain Gauge
6.4 Stress Testing by Hydraulic Fracturing Method
7 Observations of Rock Mass
7.1 Observation of Convergence Displacement of Surrounding Rock Mass
7.2 Observation of Borehole's Axial Displacement of Rock Mass
7.3 Observation of Borehole's Transverse Displacement of Rock Mass
7.4 Tiltmeter Observation on Rock Surface
7.5 Observation of Seepage Pressure in Rock Mass
Appendix A Parameter Calculations for Rock Stress
A.1 Calculation by Borehole-wall Strain Method
A.2 Calculation by Borehole Radial Deformation Meter
A.3 Calculation by Borehole-bottom Strain Method
A.4 Parameter Calculation for Space Principal Stress
Explanation of Wording in this Standard