Description:FIELD OF THE INVENTION

[501] Our Invention is related to a Evaluation of Blast-Induced Ground Vibration in Jagannathpur Opencast Project Bhatgaon area Dist-Surajpur (M/s SECL Bilaspur).

BACKGROUND OF THE INVENTION
[502] One of the most troublesome and controversial issues facing mining and other industries related to blasting is that of ground vibration and air blast produced form blasts. It goes without saying that huge mutation in the field of industries and buildings happened in all over the world, have to be companioned with a same amount of progress in the field of rocks and minerals excavation by blasting, which is considered the backbone of this industrial prosperity.

[503] For that, accurate control must to be serious restricted to minimize blasting effect on people and environment. Ground vibration induced by blasting is an environmental issue in the mining industry, when explosives are detonated in a blast hole much of the energy is used to break up and move the rock or mineral. However, there is always some energy left over and this is converted into vibration that travels away from the blast area through both the ground and air

[504] The vibration through the air is generally known as air overpressure & the vibration through ground is known as blast induced Ground vibration. The motion of the ground particles takes in three perpendicular directions viz Vertical, longitudinal and transverse directions.

[505] Blasting is one of the most economical methods used for rock-mass fragmentation and displacement of broken rocks. The typical energy source to achieve this loosening of rock mass comes from usage of explosives. During the explosive charges large quantity of energy is released. The corresponding pressure and temperature produced during blasting are about 50 GPA at 5000K respectively.

[506] However, 20%-30% of the explosive energy is used to fragment and displace of the rock mass. While the rest of the energy cannot be utilised in breaking rock and creates vibration in the surrounding rock. The parameters, which exhibit control on the amplitude, frequency and duration of the ground vibration, are divided in two groups such as non-controllable Parameters (local geology, rock characteristics and distances of the structures etc.) and Controllable Parameters (Charge Weight, Burden, spacing and specific charge, Delay Interval, Coupling, Type of Explosive, Confinement, Direction of blast progression, etc.)

[507] A detailed literature review has been carried out on the topics relevant to the research work. In the literature review, topics such as the blasting performance, seismic waves, factors affecting blast-induced ground vibration, assessment and monitoring of ground vibration, and seismic energy analysis have been discussed in details. In addition, the work performed, observations, conclusions, and suggestions by various researchers are summarized. And different techniques of ground vibration measurement are also discussed. And different models of damage based on PPV as their assessment criteria have been analysed based on which the objectives were formulated.

OBJECTIVES OF THE INVENTION
The key objectives of the present study are as follows:
1. Prediction of blast induced ground vibration in terms PPV (mm/s) as per USBM prediction approaches.
2. Calculation of safe maximum charge/delay (Q max)
3. Further, to compare the predicted PPV values with the established damage criteria of different national and international standards to evaluate any associated damage potential to nearby structures.

Scope of the Work
This study has been carried out on the evaluation of Blast induced ground vibration in opencast bench blasting in diverse aspects. The scope of the study are:
1. Impact on structures: Blast-induced ground vibrations can potentially cause damage to nearby structures, such as buildings, bridges, and infrastructure. The scope involves assessing the potential for structural damage based on the magnitude and frequency characteristics of the vibrations.
2. Human discomfort and safety: Ground vibrations from blasting can cause human discomfort, annoyance, and even potential safety hazards. The scope includes evaluating the effects on human activities, such as residential areas, workplaces, and public spaces, and establishing guidelines or regulations to ensure safety and minimize discomfort.
3. Regulatory standards and guidelines: Government agencies and industry organizations often establish regulatory standards and guidelines to ensure safe and controlled blasting operations. The scope involves developing and updating these standards based on scientific research, technological advancements, and best practices.

SUMMARY OF THE INVENTION

[508] Regression analysis is a statistical method that shows the relationship between two or more variables. Usually expressed in a graph, the method tests the relationship between a dependent variable against independent variables. Typically, the independent variable(s) changes with the dependent variable(s) and the regression analysis attempts to answer which factors matter most to that change.

[509] Regression analysis is a powerful statistical method that allows you to explore the relationship between one or more variables. It can help you understand how changes in one variable affect another, and how well you can predict future outcomes based on historical data. Regression analysis is often used for forecasting and prediction, which involves using a regression model to estimate the value of the dependent variable for new or future observations of the independent variable.

[510] The data of blast design parameters and blast-induced ground vibration observed during field experiments at Jagannathpur opencast coal mines are presented in During literature review, it was concluded that the most influencing parameters for ground vibration are Maximum safe charge Per delay (MCD), and distance of monitoring blast vibration (D). Thus, in this study, only Maximum safe charge per delay (MCD) and Monitoring Distance (D) were used for evaluation of the attenuation characteristics of blast-induced ground vibration.

[511] For this purpose, 80% of the concerning data presented in Table were selected randomly for analysis and 20% for validation of results. The data used for analysis are as presented in Table The independent variables were scaled to relate similar blast effects from various charge weights of the same explosive at various distances.

Table Data used for evaluation of blast induced ground vibration at Jagannathpur OCP Mine

Sr. No. Independent Variable Dependent Variable Calculated Scaled Distances
D MCD PPV
SD

Units
m kg mm/s m/kg^0.5
1 330 90.2 3.074 34.75
2 360 80.2 2.646 40.20
3 170 110.2 10.04 16.19
4 210 60.1 8.251 27.09
5 350 90.2 2.872 36.85
6 380 80.2 2.198 42.43
7 180 110.2 10.09 17.15
8 140 120.2 15.56 12.77
9 190 90.2 7.542 20.01
10 200 150.3 8.629 16.31
11 160 90.2 10.02 16.85
12 220 150.3 8.569 17.94
13 290 90.2 4.26 30.53
14 210 18.3 2.426 49.09
15 190 16.3 2.409 47.06
16 140 30.2 5.385 25.48
17 410 110 2.652 39.09
18 390 37 0.952 64.12
19 290 37 5.465 47.68
20 320 55 4.533 43.15
21 350 36 0.7411 58.33
22 310 130 2.547 27.19
23 420 100 2.662 42.00
24 350 30 1.536 63.90
25 320 40 2.472 50.60
26 290 37.5 5.042 47.36
27 310 90 4.7 32.68
28 330 120 3.634 30.12

[512] Scatter plot was made of the weighted independent variables and dependent variable to find out the coefficient of determination (R2). s that Square-root Scale Distance with MCD is showing strong correlation with observed PPV, having Correlation coefficient (R2) value of 0.7568, which indicates that these data can be used for development of blast-induced ground vibration model for further prediction of blast vibration of that particular experimental site.

BRIEF DESCRIPTION OF THE DIAGRAM
Fig.1: Propagation of Blast Vibration.
Fig.2: Propagation of P-wave.
Fig.3: Flow diagram of Research Methodology.
Fig.4: Micromate along with external geophone.
Fig. 5: View of Geophone coupling while vibration monitoring in behind the blast site.
Fig.6: Entrance gate of Mahamaya sugar mill
DESCRIPTION OF THE INVENTION

[513] To address the research's objectives, a research methodology was developed. This research work was conducted in Jagannathpur opencast coal mine of sedimentary formations.
[514] To fulfil the research objectives, a systematic literature review was carried out, which covered a gamut of topics related to ground vibration and their control strategy. Thereafter, the site selection for the ground vibration measurement was carried out. In selected site, blasting experiments were conducted with varying blast design parameters such as Burden (B), Spacing (S), Maximum charge per delay (MCD), Total explosives charge per round (TC). The Blast induced ground vibration have recorded at different locations. The ground vibration data recorded in terms of Peak Particle Velocity (PPV) with Distance from the blast site to the monitoring station (D).
[515] All the data of blast experiments and recorded ground vibration were compiled. A regression analysis was performed on data compiled to see the correlation with input and output the parameters concerning to ground vibration (PPV). The model developed has shown a good correlation with R2 of 0.7568. which means this model can we used for further prediction of ground vibration and calculation of maximum safe charge per delay of that particular experimental site. The developed model can be helpful for blast design and optimisation of blasting parameters.
[516] Appropriate experiments were designed to achieve the research objectives, which are presented below. The investigations are divided into two stages: blast monitoring (during blasts) and blast assessment (after blasts).
[517] Vibration monitoring at experimental site was carried out using M/s Instantel Inc., Canada make microcomputer-based seismographs namely MicroMate (Two unit). All these instruments are four-channel seismographs provided with one tri-axial transducer for monitoring of vibration (in mm/s or inch/s) and one-channel for monitoring of air overpressure/noise in dB (L) or Pa. They record vibrations in three orthogonal directions [i.e. Longitudinal (L), Vertical (V) and Transverse (T)] and peak frequency of vibration in individual directions as well as compute the peak vector sum of vibrations.
[518] These are all portable, high precision instruments which measure vibration intensity in terms of amplitude, particle velocity, frequency and air overpressure in British as well as Metric units. The instruments permit full wave recording at any instant of time for a preset duration. Sensors are having an articulation of spikes for proper coupling with the ground for more precise reading of particle velocity.
[519] One of the most critical aspects of ground vibration monitoring is the mounting (placement) of transducers in the field. Good coupling refers to the transducer that maintains proper contact with the ground. Poor coupling can cause slippage or toppling of the transducer resulting in distorted, often higher vibration levels. Most recommendations agree that the best coupling can be achieved by burying the transducer when the measurement surface consists of soil and by bolting or quick setting cement (plaster of Paris) when the measurement on surface consists of rock or concrete.
[520] In this study, altogether 20 nos. of blasting experiments were conducted in Jagannathpur open cast coal mine of Bhatgaon area SECL. During all these blasting experiments, monitoring of vibration in 35 locations were carried out using Micromate seismographs. Monitoring locations were chosen considering size of blast, mine location the distance of the Mahamaya sugar mill from blast site, presence of any domestic structures. In all the cases, measurements were carried out in the direction of Mahamaya sugar mill with an intention to record maximum vibration intensity. Blasting experiments were designed in such a way that the domestic houses of local populace do not get affected and the vibration intensity is reduced to the recommended threshold value.
[521] Considering Cylindrical explosive geometry for long cylindrical charges, Duvall and Perk of (1959), Duvall and Fogelson (1962) and Duvall et al (1963) concluded that any linear dimension should be scaled with the square root of the charge weight. They assumed the relationship in the following form [9].

PPV = K (D/Q1/2)- ß Eq. -----------------------…(2)
Where
PPV = Peak particle Velocity (mm/s).
D = Distance of measuring point to Blast site (m).
Q = Maximum safe Charge per delay in a round Blast (kg).
K= site constant.
ß= attenuation rate of ground vibration.
[522] Scaled distance (SD) is a scaling factor that relates similar blast effects from various charge weights of the same explosive at various distances. Scaled distance is calculated by dividing the distance to the structure of concern by a fractional power of the weight of the explosive material.

[523] the scaled distance equation considers the distance from the blast to the point of concern and the amount of charge weight detonated during any 8 ms interval. When ground vibrations are monitored with seismographs the ground motion is typically measured in terms of displacement, peak particle velocity and frequency.

[524] There are two excepted scaled distance formulas used in blasting, square root scaling and cube root scaling. Square root scaling is the general formula used in most regulations and general blasting situations, where the charge can be considered linear. Cube root scaling is used for blasting in the extreme near field where the charge can be considered a point charge or in explosions involving very large quantities, such as those created by nuclear explosions. Ambrose’s and Hendron first suggested cube root scaling for use in prediction of blast vibrations in the year 1968.
[525] Many times, when construction-blasting specifications are encountered, designing to a certain square root scaled distance factor is required. This is useful as a beginning estimate for vibration control and provides a conservative and safe charge weight for the test blast program. Since explosives confinement is not taken into consideration, there can and usually is a large variation in results, especially in tight blasting situations. It should be noted that small charges generate vibrations with higher frequencies and smaller displacements.
Square root Scaled Distance Formula-
SD=D/Q1/2 Eq. …(3)

Where,
SD = Scaled distance in m/kg-1/2
D = The distance from the blast site to the monitoring station in m.
Q = Maximum safe charge per delay in kg.

Cube root scaling
[526] Cube root scaling should be used for vibration prediction in the extreme near field (under 20 feet) in construction blasting. Cube root scaling can also be used as the basis for the prediction of frequency [8].
Cube Root Scaled Distance Formula-
SD= D/Q0.33 Eq…(4)
Where,
SD = Scaled distance in m/kg-1/2
D = the distance from the blast site to the monitoring station in m.
Q = Maximum safe charge per delay in kg.
[527] is a statistical method that shows the relationship between two or more variables. Usually expressed in a graph, the method tests the relationship between a dependent variable against independent variables. Typically, the independent variable(s) changes with the dependent variable(s) and the regression analysis attempts to answer which factors matter most to that change.
[528] Regression analysis is a powerful statistical method that allows you to explore the relationship between one or more variables. It can help you understand how changes in one variable affect another, and how well you can predict future outcomes based on historical data. Regression analysis is often used for forecasting and prediction, which involves using a regression model to estimate the value of the dependent variable for new or future observations of the independent variable.
[529] In this study a total 20 numbers of blast experiments were conducted and 35 blast vibration. All these observed vibration data were analysed as per USBM model for further prediction of ground vibration, PPV (mm/s)

[530] As per the present Indian standards, as mentioned in Directorate General of Mines Safety (DGMS) (Tech) (S&T) Circular No. 7 dated 29th August, 1997, depending on the type of structures and dominant excitation, the peak particle velocity (PPV) on the ground adjacent to the structure shall not exceed.

Table Regulatory limits of ground vibration according to Director General of Mine Safety (DGMS), India
Type of Structures Dominant Excitation Frequency, Hz
< 8 Hz 8 - 25 Hz > 25 Hz
(A) Buildings/structures not belong to the owner
Domestic houses /structures (Kuchha brick and cement) 5 10 15
Industrial buildings (RCC and framed structures) 10 20 25
Objects of historical importance and sensitive Structures 2 5 10
(B) Building belonging to owner with limited span of life
Domestic houses /structures (Kuchha brick and cement) 10 15 25
Industrial buildings (RCC and framed structures) 15 25 50

Safe limit of PPV for Jagannathpur Open-cast Coal Mine
[531] The closed structure to Jagannathpur Opencast coal mines which does not belongs to mine owner is Mahamaya sugar mill. The distance from mine boundary to this structure is 500 m. As per the DGMS, this structure is categorised to Industrial buildings for which the safe limit prescribed by DGMS is 10 mm/s and 20 mm/s for < 8Hz and 8-25 Hz Dominant Excitation Frequency respectively. Analysis of observed frequency analysis data reveals that 12% of recorded frequency is falling below 8 Hz. Consequently, a safe permissible limit of ground vibration of 10 mm/s has been considered for calculating safe maximum charge per delay.

Calculation of Maximum safe Charge per Delay (MCD)
[532] The safe permissible limit of ground vibration for Jagannathpur opencast Coal mine is a 10 mm/s. In equation 6, the value of PPV was kept as 10 mm/s and Maximum Safe Charge per Delay was calculated for different distances.

[533] The Boundary of Jagannathpur Open-cast coal mine, Bhatgaon is in proximity of industrial and housing structures. Therefore, prediction of blast-induced ground vibration and further estimating maximum safe charge per delay becomes vital for designing bench blasts. The closest structure to the mine boundary is Mahamaya Sugar Mill, 500 m away. As per the DGMS Circular, the recommended safe limit for such structures (industrial) is 10 mm/s corresponding to dominant frequency <8Hz.

[534] An experimental field study was carried out at Jagannathpur Open-cast coal mine to evaluate the ground vibration prediction model and determine maximum safe charge per delay. During this study, 20 nos. blast rounds were conducted with varying blast design parameters. Simultaneously, blast-induced ground vibration was monitored at different locations. The monitoring location includes Mahamaya sugar mill, domestic houses, and other prominent structures. Altogether 35 vibration data were recorded during this study. The observed vibration data were analysed as per USBM prediction equation model for further prediction of Ground vibration, PPV (mm/s). The determination coefficient (R2) of the developed model is 0.7568, which implies a strong relation between input and output parameters. The developed site-specific prediction model at 95 % confidence interval is given as PPV = 602.1146(D/vQmax)-1.384

[535] It is evident from the observed blast-induced ground vibration that the vibration level at 120 m distance is 19.44 mm/s, and it is attenuating rapidly. The ground vibration at 400 m reduced to 2.5 mm/s. Dominant Frequency of the observed vibration (PPV) ranges from 3.20 Hz to 30 Hz. Therefore, it is concluded that observed blast induced ground vibration values are safe and well within the permissible limit as per the recommendations of Directorate General of Mine Safety (DGMS).

, Claims:I/WE CLAIMS

1. Our Invention “Evaluation of Blast-Induced Ground Vibration in Jagannathpur Opencast Project Bhatgaon area Dist-Surajpur (M/s SECL Bilaspur)” is a The present study aims to evaluate the ground vibrations caused by blasting in Jagannathpur Open-cast coal mine and to determine the maximum safe charge per delay. This was accomplished by conducting a total of 20 experimental blast rounds during the various phases of field investigations. The experimental blast was carried out with varying blast design parameters both in the overburden and coal benches. In experimental blasts, the hole depth varied from 4.5 m to 6.0 m for OB benches and 1.9 m to 3.0 m for coal benches. The total charge ranged from 162 kg to 4641 kg, and the number of holes from 17 to 620 holes. Although the average maximum charge per delay in mine blasting operations is 8.10 to 150.30 kg. Comprehensive vibration monitoring was conducted during the blasting experiment. In total, vibration was monitored at 35 different locations. Monitoring locations were chosen considering the size of the blast, mine location, and distance from any domestic structures. Monitoring locations include Kerta and Dharampura villages' industrial structures and houses. Ground vibration was monitored in terms of ground particle velocity using 2 four-channel seismographs. All these are provided with one tri-axial transducer for monitoring vibration (in mm/s) and one channel for measuring air overpressure/noise in dB (L) or Pa. The instrument records vibrations in three orthogonal directions [i.e., Longitudinal (L), Vertical (V), and Transverse (T)] and the dominant frequency of vibration in individual directions as well as computes the peak vector sum of vibrations. The instruments also permit full wave recording at any moment for the duration of the recording. Sensors have an articulation of spikes for proper coupling with the ground for more precise reading of particle velocity. Observed vibration data were analyzed using the USBM predictor equation. In order to determine site constants, a least square regression model was developed based on square root scaled distances of maximum safe charge per delay (Qmax ) in kg. The distance of vibration measurement transducers from the blasting face (D) in m, and peak particle velocity (PPV) in mm/s. The determination coefficient (R2) of the developed model is 0.7568, which implies a strong relation between input and output parameters. Further, a 95 % confidence interval was used for developing a site-specific prediction model. The closest structure to the mine boundary is Mahamaya Sugar Mill, 500 m away. As per the DGMS Circular, the recommended safe limit for such structures is 10 mm/s corresponding to a dominant frequency <8Hz. It is evident from the observed blast-induced ground vibration that the vibration level at 120 m distance is 19.44 mm/s, and it is attenuating rapidly. Ground vibration at 400 m was reduced to 2.5 mm/s. The vibration frequency ranges from 3.20 Hz to 30 Hz. Therefore, it is concluded that the observed blast-induced ground vibration values are safe and well within the permissible limit as per the recommendations of the Directorate General of Mine Safety (DGMS).

2. According to claim1# the invention is to a “Evaluation of Blast-Induced Ground Vibration in Jagannathpur Opencast Project Bhatgaon area Dist-Surajpur (M/s SECL Bilaspur)” is a The present study aims to evaluate the ground vibrations caused by blasting in Jagannathpur Open-cast coal mine and to determine the maximum safe charge per delay.

3. According to claim1,2# the invention is to a was accomplished by conducting a total of 20 experimental blast rounds during the various phases of field investigations. The experimental blast was carried out with varying blast design parameters both in the overburden and coal benches. In experimental blasts, the hole depth varied from 4.5 m to 6.0 m for OB benches and 1.9 m to 3.0 m for coal benches.

4. According to claim1,2,3# the invention is to a ranged from 162 kg to 4641 kg, and the number of holes from 17 to 620 holes. Although the average maximum charge per delay in mine blasting operations is 8.10 to 150.30 kg. Comprehensive vibration monitoring was conducted during the blasting experiment.

5. According to claim1,2# the invention is to a vibration was monitored at 35 different locations. Monitoring locations were chosen considering the size of the blast, mine location, and distance from any domestic structures. Monitoring locations include Kerta and Dharampura villages' industrial structures and houses. Ground vibration was monitored in terms of ground particle velocity using 2 four-channel seismographs. All these are provided with one tri-axial transducer for monitoring vibration (in mm/s) and one channel for measuring air overpressure/noise in dB (L) or Pa.

6. According to claim1,2,3# the invention is to a instrument records vibrations in three orthogonal directions [i.e., Longitudinal (L), Vertical (V), and Transverse (T)] and the dominant frequency of vibration in individual directions as well as computes the peak vector sum of vibrations. The instruments also permit full wave recording at any moment for the duration of the recording. Sensors have an articulation of spikes for proper coupling with the ground for more precise reading of particle velocity.

7. According to claim1,2,3# the invention is to a Observed vibration data were analyzed using the USBM predictor equation. In order to determine site constants, a least square regression model was developed based on square root scaled distances of maximum safe charge per delay (Qmax) in kg. The distance of vibration measurement transducers from the blasting face (D) in m, and peak particle velocity (PPV) in mm/s.

8. According to claim1,2,3,4# the invention is to a determination coefficient (R2) of the developed model is 0.7568, which implies a strong relation between input and output parameters. Further, a 95 % confidence interval was used for developing a site-specific prediction model. The closest structure to the mine boundary is Mahamaya Sugar Mill, 500 m away. As per the DGMS Circular, the recommended safe limit for such structures is 10 mm/s corresponding to a dominant frequency <8Hz.

9. According to claim1,2,3,4# the invention is to a evident from the observed blast-induced ground vibration that the vibration level at 120 m distance is 19.44 mm/s, and it is attenuating rapidly. Ground vibration at 400 m was reduced to 2.5 mm/s. The vibration frequency ranges from 3.20 Hz to 30 Hz. Therefore, it is concluded that the observed blast-induced ground vibration values are safe and well within the permissible limit as per the recommendations of the Directorate General of Mine Safety (DGMS).