What is the good value of RQD?
7.2 Classification Parameters
| Rock Quality | RQD Index in % |
|---|---|
| Poor | 25–50 |
| Fair | 50–75 |
| Good | 75–90 |
| Excellent | 90–100 |
What do you mean by RQD how it is determined?
Determination of RQD. RQD was proposed by Deere (1964) as a measure of the quality of borehole core. The RQD is defined as the ratio (in percentage) of the total length of sound core pieces that is 0.1 m (4 inch) or longer to the length of the core run.
What is RQD used for?
RQD is used to evaluate quality of rocks such as degree and depth of weathering, zones of rock weakness and fracturing. This information is used for determining the depth of foundations, bearing capacity of rocks, settlement and sliding possibilities of foundations.
How do I calculate core recovery and RQD?
RQD is defined as the sum of the core samples having a length greater than 100mm divided by the total length considered. RQD value is calculated as a percentage value. Therefore, the above ration shall be multiply by 100. Let see how it is calculated in practice.
What is rock mass quality?
rock-mass quality (RMQ) A classification of rock for engineering purposes, based on the number of major joints or other discontinuities (planes of weakness) in it, their orientation, and their spacing.
Who developed RQD?
RQD was developed in 1964 by D. U. Deere*. It is determined by measuring the core recovery percentage of core chunks that are greater than 100 mm in length.
What is meant by core recovery?
Term. Definition. Core recovery. In rock core drilling, the amount of the drilled rock withdrawn as core (i.e., recovered); generally expressed as a percentage of the cored interval or coring “run”. Examples: a 5 ft coring run that yields 4 ft of rock core constitutes a recovery of 80 percent.
What are the factors that affect rock mass quality?
The geology, geo-tectonic, topographic environment as well as weather influence the overall rock mass quality condition in the vicinity of concern. The rock mass quality is mainly defined by rock mass strength and deformability properties.
What is the difference between rock and rock mass?
Rock material is the term used to describe the intact rock between discontinuities; it might be represented by a hand specimen or piece of drill core examined in the laboratory. The rock mass is the total in-situ medium containing bedding planes, faults, joints, folds and other structural features.
Is RQD a code?
RQD shall be based on IS : 11315 ( Part 11) – 1985*.
How is core recovery measured?
The easiest way to characterize the amount of material recovered during rock coring is to calculate “core recovery” as the amount (i.e. length) of recovered material divided by the total length of the core run (presented as a percentage).
What is recovery ratio?
Cost Recovery Ratio. This is the ratio of fare revenue to total operating costs, and is a key indicator of financial performance. It may most conveniently be expressed as a percentage.
What are the four factors that influence rock strength?
Factors that influence the strength of a rock and how it will deform include temperature, confining pressure, rock type, and time.
How do you determine the quality of rock mass?
Classification of the rock mass
Rock mass quality varies from Qmin to Qmax, so the average rock mass quality of (Qmax × Qmin)1/2 may be assumed in the design calculations. The Q-values will be higher where a tunnel boring machine (TBM) or a road header is used to smooth the surface of excavation.
What is RMR and RQD?
RQD is determined from rock cores or volumetric joint count; it is the percentage of rock cores in one meter of drill run. RMR is determined as an algebraic sum of ratings for all of the parameters.
Why do we classify rock mass?
The main benefits of rock mass classifications: Improve the quality of site investigations by calling for the minimum input data as classification parameters. Provide quantitative information for design purposes. Enable better engineering judgement and more effective communication on a project.
What is total core recovery?
Definition. The total core recovery (TCR) is defined as the pro- portion of core recovered to the total length of the drilled run. The core run is the length reported by the driller as the actual depth penetrated. The TCR includes both the solid core and the non-solid (or non-intact) core.
What is core recovery explain?
i. The proportion of the drilled rock column recovered as core in core drilling. The amount withdrawn generally is expressed as a percentage of the theoretical total in general terms, as excellent, good, fair, or poor. Compare with: core loss.
What is a good cost recovery ratio?
If it equals 100%, the operation as a whole is breaking even; if it exceeds 100% it is earning a surplus, while if it is below 100% the operation is losing money. Typical cost recovery ratios for a profitable bus operation lie between 110% and 115%.
How is recovery value calculated?
Calculating Recovery Rate
Next, divide the total payment amount by the total amount of debt. The result is the recovery rate. For example, during one week you extended $15,000 in credit and received $2,000 in payments, therefore $2,000 / $15,000 = 13.33% recovery rate for the week.
What are the three 3 factors controlling the deformation of rock?
The three types of stresses that rocks commonly undergo are tensional stress, compressional stress, and shear stress.
What two things determine the strength of a rock?
The principal factors controlling the strength of solid rocks are: I) mineral composition, structure and texture; 2) bedding, jointing and anisotropy; 3) water content; 4) state of stress in the rock mass.
What is Q value of rock?
The Q-value in an undisturbed rock mass may be different. The Q-system is a classification system for rock masses with respect to stability of underground openings. Based on estimation of six rock mass parameters, a Q-value for a rock mass can be calculated. This value gives a description of the rock mass quality.
Why is RMR important?
Resting metabolic rate (RMR), also called resting energy expenditure, is important to understand because it typically accounts for the largest portion of total energy needs (6). RMR is typically defined as the energy required by the body in a resting condition (3).
What is a good resting metabolic rate?
1,200 to 2,000 kcal/day
RMR normally ranges from 1,200 to 2,000 kcal/day (from 1,400-1,600 kcal/day in most people). Heavier people have higher RMR because they have more mass to support. Each pound of muscle burns to produce 6-7 kcal/day. Weight loss occurs only when our energy expenditure is greater than our caloric intake.