CN-116773669-B - Method for measuring cohesive force and internal friction angle of broken rock mass

Abstract

The invention discloses a method for measuring cohesion and internal friction angle of broken rock, which comprises the steps of firstly, taking broken rock to be measured to prepare a rock test piece, and obtaining cohesion c 0 and internal friction angle of complete rock in the rock test piece Basic friction angle of rock And step two, calculating a damage variable D of the rock test piece, and step three, obtaining cohesive force and an internal friction angle of the broken rock mass in the loading process. According to the method, the calculated parameters are measured through measured data, so that human errors are reduced, nondestructive detection is the main measurement, the workload is small, and high-frequency measurement can be performed in the construction process.

Inventors

• LIU YONGSHENG
• CHEN QIAO
• ZHANG JICHAO
• YIN LONG
• YOU JINHU
• NIU FUSHENG
• HONG KAIRONG
• PAN YUE
• XIE TAO
• ZHANG LIMENG
• YANG CHAOSHUAI
• LI ZHIJUN
• DAI RUNJUN
• FENG HUANHUAN

Assignees

• 中铁隧道局集团有限公司

Dates

Publication Date

20260505

Application Date

20230428

Claims (2)

1. 1. A method for dynamically measuring cohesion and internal friction angle of broken rock mass, characterized in that the method comprises the following steps: step one, taking broken rock to be measured to prepare a rock test piece, and obtaining the cohesive force of complete rock in the rock test piece And internal friction angle And the basic friction angle of the rock ; Step two, calculating a damage variable D of the rock test piece: Measuring longitudinal wave velocity of intact rock before loading rock test piece Transverse wave velocity of intact rock ; The rock test piece is loaded and compressed, the wave speed of the test piece is synchronously detected in the loading and compressing process, a plurality of wave speed values are obtained, and the wave speed values are sequentially substituted into the formula (1): (1); Wherein: for the longitudinal wave velocity of the complete rock, For the shear wave velocity of the complete rock, Is the wave velocity of the longitudinal wave of the rock mass, The shear wave velocity of the rock mass is the wave velocity of the rock mass, E is the elastic modulus of the rock mass, and E 0 is the elastic modulus of the complete rock; Calculating to obtain damage variable values corresponding to a plurality of wave speeds; step three, acquiring cohesive force and internal friction angle of the crushed rock mass in the loading process: Step 3.1, obtaining (85); Step 3.2, before the rock yields, is represented by formulas (86) and (88): (86); (88); determination of And ; From the formula (14), Obtaining the cohesive force of broken rock And internal friction angle ; Wherein: axial strain, which is the critical point of elastic deformation; Is the proportionality coefficient of the critical point; Axial stress which is the critical point of elastic deformation; Is the maximum principal stress; is the elastic modulus of the rock mass; Is the included angle between the shearing surface and the action surface of the maximum principal stress; The modulus of elasticity of the complete rock; to close the initial length of the crack; To open the initial length of the crack; Is the length of the shearing surface; The initial length of the test piece before loading; To close the crack length, In order to open the crack length, Is the damage variable in the elastic deformation stage, A is the total area of the shearing surface, For a complete rock area, In order to close the crack area, Is normal stress on the shear plane As the degree of closure of the crack(s), Is the shear strength of the rock mass; Step four, obtaining damage variables in the step two and the step three and corresponding cohesive force through a least square method And internal friction angle The fitting formula is as follows: (96); (97); Wherein: 、 、 And Are fitting constants, and are obtained through fitting, and the values of the fitting constants are related to lithology; And fifthly, acquiring the longitudinal wave velocity and the transverse wave velocity of the field broken rock mass, calculating to obtain the damage variable of the rock mass, and obtaining the cohesive force and the internal friction angle of the rock mass through formulas (96) and (97).
2. 2. A method for dynamic measurement of cohesion and internal friction angle of crushed rock according to claim 1, wherein, (61); (62); Wherein: the diameter of the test piece is the diameter of the test piece, Is the length of the complete rock in longitudinal section.

Description

Method for measuring cohesive force and internal friction angle of broken rock mass Technical Field The invention belongs to the technical field of rock engineering, and particularly relates to a method for measuring cohesive force and internal friction angle of broken rock mass. Background In the exploration and construction of rock engineering, the physical and mechanical parameters of rock are usually obtained by adopting an indoor rock mechanical test, and then the physical and mechanical parameters of the rock are reduced according to the breaking condition of the rock mass, so that the physical and mechanical parameters of the rock mass are indirectly obtained. The measuring method mainly has two defects of (1) obtaining the reduction parameters (such as GSI) by looking up a table according to the breaking condition of the rock mass when the physical mechanical parameters of the rock are reduced, having great subjectivity and relying on personnel experience, and (2) changing the stress strain state of the rock mass in real time along with the construction, wherein the measuring method usually has low measuring frequency and is difficult to obtain the physical mechanical parameters of the rock mass in real time. Aiming at the two problems, the invention provides a method for measuring the cohesive force and the internal friction angle of the broken rock mass, the calculated parameters are all measured by measured data, the human error is reduced, the measurement is mainly nondestructive detection, the workload is small, and the high-frequency measurement can be carried out in the construction process. Disclosure of Invention The invention aims to provide a method for measuring the cohesive force and the internal friction angle of a broken rock mass, wherein the calculated parameters are measured through measured data, so that human errors are reduced, the measurement is mainly based on nondestructive detection, the workload is small, and the high-frequency measurement can be performed in the construction process. The invention adopts the following technical scheme that the method for calculating the damage variable of the broken rock mass comprises the following steps: setting a rock mass to be composed of two parts of complete rock and gap cracks, wherein the rock mass has potential shearing fracture surfaces under the action of maximum main stress and minimum main stress, and the shearing fracture surfaces are composed of the complete rock, closed cracks and open cracks; void cracks in a rock mass are defined as damage to the rock mass, expressed by a damage variable D: (1); Wherein: for the longitudinal wave velocity of the complete rock, For the shear wave velocity of the complete rock,Is the wave velocity of the longitudinal wave of the rock mass,Is the wave velocity of the transverse wave of the rock mass,For the density of the rock mass,Poisson's ratio for rock mass; for the longitudinal wave velocity of the complete rock, Is the transverse wave velocity of the complete rock. The invention also discloses a method for dynamically measuring the cohesive force and the internal friction angle of the broken rock mass, which comprises the following steps: The method comprises the steps of taking a rock test piece, setting a rock body to be composed of two parts of complete rock and gap cracks, enabling the rock body to have potential shearing fracture surfaces under the action of maximum principal stress and minimum principal stress, enabling the shearing fracture surfaces to be composed of complete rock, closing cracks and opening cracks, defining the gap cracks in the rock body as damage of the rock body, and representing the damage variable D. Step A, obtaining D: (1); Step B (85); Open crack length before rock yieldsThe closure degree of the crack is as follows: (86); the loss variable D of the test piece can be obtained in real time by monitoring the wave speed in real time in the compression process. According to the relation between damage variable and crack: (87); Before yielding: (88); Derived from formulas (86) and (88) And; Shear strength of rock massThe method comprises the following steps: (14); obtaining the cohesive force of broken rock mass And internal friction angle; Wherein: for the longitudinal wave velocity of the complete rock, For the shear wave velocity of the complete rock,Is the wave velocity of the longitudinal wave of the rock mass,Is the wave velocity of the transverse wave of the rock mass,For the density of the rock mass,Poisson's ratio for rock mass; axial strain, which is the critical point of elastic deformation; Is the proportionality coefficient of the critical point; Axial stress which is the critical point of elastic deformation; Is the maximum principal stress; is the elastic modulus of the rock mass; Is the included angle between the shearing surface and the action surface of the maximum principal stress; The modulus of elasticity of the complete rock; t