CN112378786A - Method for measuring compressive strength of rock on site - Google Patents

Method for measuring compressive strength of rock on site Download PDF

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Publication number
CN112378786A
CN112378786A CN202011165427.9A CN202011165427A CN112378786A CN 112378786 A CN112378786 A CN 112378786A CN 202011165427 A CN202011165427 A CN 202011165427A CN 112378786 A CN112378786 A CN 112378786A
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Prior art keywords
compressive strength
rock
rock sample
measuring
pressing plate
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CN202011165427.9A
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唐静静
徐进贤
葛秀花
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Lianyungang Construction Engineering Quality Testing Center Co ltd
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Lianyungang Construction Engineering Quality Testing Center Co ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/30—Investigating strength properties of solid materials by application of mechanical stress by applying a single impulsive force, e.g. by falling weight
    • G01N3/303—Investigating strength properties of solid materials by application of mechanical stress by applying a single impulsive force, e.g. by falling weight generated only by free-falling weight
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/02—Details
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/003—Generation of the force
    • G01N2203/0032—Generation of the force using mechanical means
    • G01N2203/0039—Hammer or pendulum

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  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
  • Investigation Of Foundation Soil And Reinforcement Of Foundation Soil By Compacting Or Drainage (AREA)

Abstract

The invention discloses a method for measuring the compressive strength of rock on site, which comprises the following test steps: fixing an instrument on a flat and high-hardness ground or other flat rocks, leveling, carefully cleaning two guide rods, coating lubricating oil on the guide rods, placing a rock sample in the middle of a lower pressing plate, covering the lower pressing plate with an upper pressing plate, wherein the rock sample is a rock core, the height of the rock sample is not more than 10cm, screwing down a lower pressing plate fixing nut to fix the rock sample, measuring the initial depth of the rock sample by using a depth gauge, adjusting a measuring nail to just contact the surface of the rock sample, placing a cushion block on the measuring nail, lifting a heavy hammer to a preset height, releasing a pull rope, vertically hitting a nail pressure bearing plate by the heavy hammer along the guide rods, installing automatic acquisition equipment on the instrument, reading the compressive strength in real time and uploading a test result in real time; through the on-site direct test, the sample can be a rock block or a rock core, the investigation efficiency is effectively improved, and for the construction of the drilled pile, the strength of the bearing stratum can be rapidly judged on site through the method, so that the generation of manual misjudgment is avoided.

Description

Method for measuring compressive strength of rock on site
Technical Field
The invention relates to a method for measuring the compressive strength of rock on site, belonging to the technical field of geotechnical engineering.
Background
At present, in geotechnical engineering investigation and construction, a basic test method for the compressive strength of a rock taken out of a drill hole comprises the following steps: the saturated uniaxial test method and the point load test method need to take a rock core or a rock block to a laboratory for testing. The influence on the on-site rock property judgment and the rock-entering depth judgment efficiency in construction is large.
Disclosure of Invention
The invention provides a method for measuring the compressive strength of rock on site, which is used for overcoming the defect that the rock property in the prior art has great influence on the efficiency of judging the rock-entering depth in construction.
In order to solve the technical problems, the invention provides the following technical scheme:
the invention discloses a method for measuring the compressive strength of rock on site, which comprises the following test steps:
1. the instrument is fixed on a flat and hard ground (such as a concrete pavement) or other flat rocks, leveled, and the two guide rods are carefully cleaned and coated with lubricating oil.
2. And placing the rock sample in the middle of the lower pressing plate, and covering the upper pressing plate. If the rock sample is a core, the height should not exceed 10 cm. Screwing down the lower pressing plate fixing nut to fix the rock sample, and measuring the initial depth of the rock sample by using a depth gauge;
3. and adjusting the measuring nail to just contact the surface of the rock sample, and placing the cushion block on the measuring nail.
4. The heavy hammer is lifted to a preset height, the pull rope is released, and the heavy hammer strikes the nail shooting bearing plate along the guide rod vertically. And adjusting the drop distance according to the actually measured penetration depth to ensure that the penetration depth is distributed in the range of 3.0mm-10.0 mm.
5. And taking out the cushion block and determining, measuring the penetration depth by using a depth gauge, and reading the compressive strength value of the rock sample at the penetration depth, namely the compressive strength curve or the comparison table.
6. Testing each rock sample for 9 times, and taking the standard value of the compressive strength as the compressive strength of the rock sample; the standard value calculation method comprises the following steps:
Figure RE-GDA0002817770480000021
Figure RE-GDA0002817770480000022
Figure RE-GDA0002817770480000023
Figure RE-GDA0002817770480000024
Figure RE-GDA0002817770480000025
in the formula: phi is am-mean compressive strength (MPa);
σf-standard deviation of compressive strength (MPa);
delta-coefficient of variation of compressive strength;
γs-counting the correction factors;
φkstandard value of compressive strength (MPa).
7. And automatic acquisition equipment is arranged on the instrument, so that the compressive strength is read in real time, and the test result is uploaded in real time.
Furthermore, the smooth degree of the sliding of the guide rod has great influence on the test result, and lubricating oil should be carefully cleaned and coated before each test.
Furthermore, the hardness of the ground has a great influence on the test result, so that a sufficiently hard ground surface needs to be selected for the test.
Further, the compression strength comparison table is a parameter for recording penetration depth, strength and falling distance, wherein the unit of the penetration depth is mm, the unit of the strength is MPa, and the unit of the falling distance is cm.
Furthermore, the compression strength comparison table needs to collect various data to establish a local authority database.
The invention has the following beneficial effects: according to the method, through a field direct test, the sample can be a rock block or a rock core, and the investigation efficiency is effectively improved. For the construction of the drilled pile, the strength of the bearing stratum can be rapidly judged on site by the method, and the generation of manual misjudgment is avoided.
Detailed Description
The preferred embodiments described herein are merely illustrative and explanatory of the invention and are not restrictive thereof.
Examples
A method for measuring the compressive strength of rock in situ comprises the following test steps:
1. the instrument is fixed on a flat and hard ground (such as a concrete pavement) or other flat rocks, leveled, and the two guide rods are carefully cleaned and coated with lubricating oil.
2. And placing the rock sample in the middle of the lower pressing plate, and covering the upper pressing plate. If the rock sample is a core, the height should not exceed 10 cm. Screwing down the lower pressing plate fixing nut to fix the rock sample, and measuring the initial depth of the rock sample by using a depth gauge;
3. and adjusting the measuring nail to just contact the surface of the rock sample, and placing the cushion block on the measuring nail.
4. The heavy hammer is lifted to a preset height, the pull rope is released, and the heavy hammer strikes the nail shooting bearing plate along the guide rod vertically. And adjusting the drop distance according to the actually measured penetration depth to ensure that the penetration depth is distributed in the range of 3.0mm-10.0 mm.
5. And taking out the cushion block and determining, measuring the penetration depth by using a depth gauge, and reading the compressive strength value of the rock sample at the penetration depth, namely the compressive strength curve or the comparison table.
6. Testing each rock sample for 9 times, and taking the standard value of the compressive strength as the compressive strength of the rock sample; the standard value calculation method comprises the following steps:
Figure RE-GDA0002817770480000041
Figure RE-GDA0002817770480000042
Figure RE-GDA0002817770480000043
Figure RE-GDA0002817770480000044
Figure RE-GDA0002817770480000045
in the formula: phi is am-mean compressive strength (MPa);
σf-standard deviation of compressive strength (MPa);
delta-coefficient of variation of compressive strength;
γs-counting the correction factors;
φkstandard value of compressive strength (MPa).
7. And automatic acquisition equipment is arranged on the instrument, so that the compressive strength is read in real time, and the test result is uploaded in real time.
Note that:
1) the hardness of the field has a great influence on the test result, and the field surface with enough hardness is selected for testing.
2) The smoothness of the guide rod sliding has a great influence on the test results, and lubricating oil should be carefully cleaned and coated before each test.
3) And establishing a penetration depth curve or a comparison table, wherein the table is used for collecting enough data and establishing a local authority database.
4) The compression strength comparison table is a parameter for recording the penetration depth, the strength and the falling distance, wherein the unit of the penetration depth is mm, the unit of the strength is MPa, and the unit of the falling distance is cm.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (5)

1. A method of in situ measurement of compressive strength of rock, characterised in that the testing step comprises:
1) fixing an instrument on a flat and high-hardness ground or other flat rocks, leveling, carefully cleaning the two guide rods, and coating lubricating oil on the guide rods;
2) placing the rock sample in the middle of a lower pressing plate, covering an upper pressing plate, wherein the rock sample is a rock core, the height of the rock sample is not more than 10cm, screwing down a fixing nut of the lower pressing plate to fix the rock sample, and measuring the initial depth of the rock sample by using a depth gauge;
3) adjusting the measuring nail to just contact the surface of the rock sample, and placing the cushion block on the measuring nail;
4) lifting a heavy hammer to a preset height, releasing a pull rope, enabling the heavy hammer to vertically hit the nail shooting pressure bearing plate along a guide rod, and adjusting the drop distance according to the actually measured penetration depth to enable the penetration depth to be distributed in the range of 3.0mm-10.0 mm;
5) taking out the cushion block and determining, measuring the penetration depth by using a depth gauge, and reading the compressive strength value of the rock sample at the penetration depth, namely the compressive strength curve or a comparison table;
6) testing each rock sample for 9 times, and taking the standard value of the compressive strength as the compressive strength of the rock sample;
the standard value calculation method comprises the following steps:
Figure FDA0002745625650000011
Figure FDA0002745625650000012
Figure FDA0002745625650000013
Figure FDA0002745625650000014
Figure FDA0002745625650000015
in the formula: phi is am-mean compressive strength (MPa);
σf-standard deviation of compressive strength (MPa);
delta-coefficient of variation of compressive strength;
γs-counting the correction factors;
φk-standard value of compressive strength (MPa);
7) and automatic acquisition equipment is arranged on the instrument, so that the compressive strength is read in real time, and the test result is uploaded in real time.
2. The method of claim 1, wherein the hardness of the ground has a greater effect on the test results, so that a sufficiently hard ground surface is selected for testing.
3. The method for on-site measurement of compressive strength of rock as claimed in claim 1, wherein the smoothness of sliding of said guide rod has a great influence on the test results, and the lubricating oil should be carefully cleaned and applied before each test.
4. The method of on-site measurement of compressive strength of rock of claim 1, wherein the compressive strength look-up table is a table of parameters describing penetration depth in mm, strength in MPa and drop distance in cm.
5. The method of claim 4, wherein the compressive strength comparison table is used to collect a plurality of data to build a local authoritative database.
CN202011165427.9A 2020-10-27 2020-10-27 Method for measuring compressive strength of rock on site Pending CN112378786A (en)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0678957B2 (en) * 1986-03-24 1994-10-05 財団法人電力中央研究所 Bedrock pressure detector
CN103674739A (en) * 2012-09-24 2014-03-26 中国石油化工股份有限公司 Mud shale brittle nature experimental device and experimental analysis method thereof
CN203551275U (en) * 2013-11-28 2014-04-16 国家电网公司 Portable in-service electric pole concrete compressive strength field measuring instrument
CN104990866A (en) * 2015-07-23 2015-10-21 三峡大学 Method utilizing nail shooting to measure rock cohesion C and internal friction angle (Phi)
CN109708985A (en) * 2019-03-08 2019-05-03 扬州大学 A kind of soft rock strength test needle penetrometer and its application method
CN209485892U (en) * 2019-01-23 2019-10-11 深圳市爱华勘测工程有限公司 A kind of compressive strength of rock measuring device

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0678957B2 (en) * 1986-03-24 1994-10-05 財団法人電力中央研究所 Bedrock pressure detector
CN103674739A (en) * 2012-09-24 2014-03-26 中国石油化工股份有限公司 Mud shale brittle nature experimental device and experimental analysis method thereof
CN203551275U (en) * 2013-11-28 2014-04-16 国家电网公司 Portable in-service electric pole concrete compressive strength field measuring instrument
CN104990866A (en) * 2015-07-23 2015-10-21 三峡大学 Method utilizing nail shooting to measure rock cohesion C and internal friction angle (Phi)
CN209485892U (en) * 2019-01-23 2019-10-11 深圳市爱华勘测工程有限公司 A kind of compressive strength of rock measuring device
CN109708985A (en) * 2019-03-08 2019-05-03 扬州大学 A kind of soft rock strength test needle penetrometer and its application method

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Application publication date: 20210219