Claims:We claim,
1. A method used to determine the subsidence of a location under mining site comprising the steps of

i) providing an arrangement of seven pillars wherein five pillars comprises first boundary pillar, second boundary pillar, third boundary pillar, fourth boundary pillar and fifth boundary pillar wherein the fifth pillar being directed to the middle of the boundary pillars and two pillars comprises first subsidence pillar and second subsidence pillar wherein the subsidence pillars being placed so as to get the distance of at least 1 meter apart.
ii) taking a reading of the boundary pillars with respect to first subsidence pillar and the reading as obtained is recorded;
iii) taking a reading of the boundary pillars with respect to second subsidence pillar and the reading as obtained is recorded;
iv) comparing the readings;
wherein the pillars are vertically arranged.

Dated this 21st day of November, 2018

(Dr. Ushoshi Guha)
Patent Agent (IN/PA 720)
Of Lex-Regia
For the Applicant
, Description:
FORM-2
THE PATENTS ACT, 1970
(39 OF 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(SECTION 10, RULE 13)

TITLE
“A METHOD USED TO DETERMINE THE SUBSIDENCE AT A MINING SITE”

APPLICANT(S)
MOIL LIMITED
(A Government of India Enterprise)
1-A, MOIL Bhawan,
Katol Road, Chaoni,
Nagpur-440 013
Maharashtra, India

The following specification particularly describes the nature of the invention and the manner in which it is to be performed

FIELD OF THE INVENTION
The present invention relates to mining sectors. More particularly, the present invention relates to a novel method that could determine the subsidence of a location in micro-level at mining sites.
BACKGROUND OF THE INVENTION
Subsidence is an inevitable phenomenon of ground movement caused by various manmade and natural activities. The economic prosperity by the exploitation of the hidden resources in the earth is always accompanied by the adverse impacts of subsidence. Subsidence due to underground coal/ore mining has been reported from almost all parts of the world and India facing very severe problems of subsidence in some of its mining fields.
"Mine Subsidence" is defined as the movement of the ground surface as a result of readjustments of the overburden due to collapse or failure of underground mine working. Surface subsidence features usually take the form of either sinkhole or troughs.
"Mine Subsidence" does not include lateral or vertical ground movement caused by earthquake, landslide, volcanic eruption, soil conditions, soil erosion, soil freezing and thawing, improperly compacted soil, construction defects, roots of trees and shrubs or collapse of storm and sewer drains and rapid transit tunnels.
In short, when the roof of subsurface mines collapses, it causes the ground above to sink or subside.
Subsidence control measures can be taken in the following three stages:
(1) Prediction
(2) Prevention
(3) Protection

Prior Art
CN105627981 discloses a mining subsidence deformation prediction and forecast system. The system includes a data acquisition module, a man-machine interface module, a central processing unit, a data analysis processing module, a graphics rendering module, a regression calculation module, a prediction analysis module, an expert recommendation module, a simulation model construction module, a virtual sensor, a virtual actuator and a simulation analysis module; the virtual actuator executes analysis periodically so as to feed back a structure to the simulation analysis module; the simulation analysis module automatically extracts data and transmits the data to the virtual sensor; and the virtual sensor automatically displays results.

CN103541376 discloses a foundation deformation prediction method for a coal mining subsidence area foundation under the condition of repeated mining, and relates to the technical fields of geotechnical engineering, mining and disaster preventing and controlling. The method comprises the steps that a mode of parameters of a current disturbance rock mass is recognized according to the surface displacement of current mining monitoring, the iterative step corresponding to the current state is determined according to the relation curve between the calculation surface displacement of the current mining state and the iterative step, and the dynamic analysis corresponding to the current monitoring displacement is carried out according to year-by-year mining plan. The foundation deformation prediction method for the coal mining subsidence area foundation under the condition of repeated mining effectively achieves the purposes of determining the parameters of the rock mass through the numerical analysis and determining the iterative step.

CN103091676 discloses a mining area surface subsidence synthetic aperture radar interferometry monitoring and calculating method belongs to mining area surface subsidence monitoring and calculating method. The method comprises the following steps: having format conversion, calibration, pre-filtering and interference to interferometric synthetic aperture radar (InSAR) data to obtain an InSAR interference phase, eliminating flat ground effect, an terrain phase and orbit errors of the interference phase by means of precise orbit data and an external dynamic effect model (DEM), obtaining phase values which only contain deformation information of a ground surface after filtering to residual phases, on the condition of large deformation gradient, through phase unwrapping, obtaining deflection of the edge of a mining subsidence basin, fusing the deflection with a few ground measured data, reversely deducing probability integral method parameters of the subsidence basin through a genetic algorithm, calculating sinking values of an arbitrary point of the whole surface subsidence basin through required probability integral method parameters and geological mining data, and therefore mining subsidence deformation field is produced.

CN103606019 discloses the mine goal overlying stratum movement prediction technology, and provides a goaf overlying stratum sedimentation dynamic prediction method based on a time-space relationship. Bulk mining of an underground mine often causes sedimentation of overlying strata, as a result, safety production in the mine is affected, threats is caused to life and property of people, and the ecological environment is damaged at the same time. Overlying stratum sedimentation is affected by multiple complex factors, so that the prediction of overlying stratum sedimentation is an international problem currently in the field. According to the goaf overlying stratum sedimentation dynamic prediction method based on the time-space relationship, overlying stratum sedimentation is divided into four types by means of summarizing and analyzing a large number of mine sedimentation materials, and by means of analyzing the relation between the overlying stratum sedimentation volume, sedimentation time, sedimentation speed and acceleration, an overlying stratum sedimentation time-space relationship dynamic prediction model conforming to different sedimentation types is obtained finally.

However, micro-level subsidence may not be predicted from the prior arts method. Accordingly, there is a need to provide a method that could determine the subsidence at micro-level.

OBJECTIVE OF THE INVENTION
It is an objective of the invention is to provide a method that could determine the subsidence of mining sites.
It is another objective of the invention is to provide a method that could determine the subsidence at micro-level.
It is yet another objective of the present invention is to minimize the surface subsidence in a forest.
It is yet objective of the invention is to provide a simple method to determine the subsidence of mining sites.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, there is provide A method used to determine the subsidence of a location under mining site comprising the steps of
i) providing an arrangement of seven pillars wherein five pillars comprises first boundary pillar, second boundary pillar, third boundary pillar, fourth boundary pillar and fifth boundary pillar wherein the fifth pillar being directed to the middle of the boundary pillars and two pillars comprises first subsidence pillar and second subsidence pillar wherein the subsidence pillars being placed so as to get the distance of at least 1 meter apart.
ii) taking a reading of the boundary pillars with respect to first subsidence pillar and the reading as obtained is recorded;
iii) taking a reading of the boundary pillars with respect to second subsidence pillar and the reading as obtained is recorded;
iv) comparing the readings;
wherein the pillars are vertically arranged.
In accordance with these and other objects which will become apparent hereinafter, the instant invention will now be described with particular reference to the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a representation of a borehole in the mine in accordance with the present invention;
Figure 2 is a representation of unexploited ore body thickness in accordance with the present invention;
Figure 3 is a representation of the geological cross section of winze at 70’L in accordance with the present invention;
Figure 4 illustrates the 7 pillars arrangement for subsidence prediction wherein 4(a) illustrates the arrangement and 4(b) is an image of the arrangement in accordance with the present invention;
Figure 5 illustrates the monitoring of 5 pillars with reference to subsidence pillar wherein 5(a) illustrates the monitoring and 5(b) is an image of the monitoring in accordance with the present invention;
Figure 6 is a representation of 2D numerical model in accordance with the present invention;
Figure 7 is a representation of condition of the roof of 4 lifts in accordance with the present invention;
Figure 8 is the location plan of measuring stations for subsidence in accordance with the present invention; and
Other objects, features and advantages of the inventions will be apparent from the following detailed description in conjunction with the accompanying drawings of the inventions.
DETAILED DESCRIPTION OF THE INVENTION
Present invention provides a method that can determine the subsidence of mining sites at micro level. In order to get a subsidence profile along the major and minor axis of an extraction panel, subsidence – monitoring lines are made along the face- advanced direction and across pit.
According to present invention, the 3D model essentially consist of total 7 pillars, out of which 5 boundary pillars (i.e. first boundary pillar, second boundary pillar, third boundary pillar, fourth boundary pillar and fifth boundary pillar) and 2 subsidence pillars.
In order to determine the subsidence of a location, the present invention comprising the steps of:
i) providing an arrangement of seven pillars wherein five pillars comprises first boundary pillar, second boundary pillar, third boundary pillar, fourth boundary pillar and fifth boundary pillar wherein the fifth pillar being directed to the middle of the boundary pillars and two pillars comprises first subsidence pillar and second subsidence pillar wherein the subsidence pillars being placed so as to get the distance of at least 1 meter apart.
ii) taking a reading of the boundary pillars with respect to first subsidence pillar and the reading as obtained is recorded;
iii) taking a reading of the boundary pillars with respect to second subsidence pillar and the reading as obtained is recorded;
iv) comparing the readings;

In the present arrangement, only vertical movements of the observation stations are measured. Since the observations are localized, a net work can be formed along the area with equal distance between points called boundary pillars (BP). The said network is the network of boundary pillars that are erected along the boundary line of the area under mining. This network gives more information about the pattern of subsidence development. The number of points (pillars) for measurement is compared to the earlier layout. When the distance between two points is less, more precise information about trough formation is obtained. For the measurements of horizontal and vertical movements, a 10m distance between two points is adopted. This distance between two pillars depends upon the area under mining. The decision of this distance is taken by the mine surveyor after surveying of the area under mining. There is no prescribed pattern of subsidence layout in the mine rules. Therefore, at each mine, observation station lines are laid down according to the understanding of the mine surveyor.

Monitoring stations can be established in addition to identifiable points (BP) for monitoring the deformation or the ground movements of an area.

Periodic monitoring is carried out for both horizontal and vertical movement measurements with the help of standard equipments. This monitoring can also be carried out using global positioning satellite and remote sensing. The prediction model is established using an adopted subsidence prediction technique.

The predictions are made based on the data collected over the period of time with wide variations, it is not possible to accurately predict any value, but can be predicted within the permissible limits. In Britain, a maximum variation of plus or minus 10 percent was considered acceptable in subsidence. If any important structure is to be protected strictly, then the need of accuracy arises.

The 3D model comprises of 5 pillars that are necessary for monitoring with respect to boundary points (BP). But these 5 pillars itself cannot improve the accuracy since it does not have reference readings for comparison and hence accurate calculations are not possible. Subsidence Pillars SPI and SPII provide the comparable reference readings for micro level prediction of subsidence. A set of these 7 pillars is referred as a station. Depends on the size of the area and geographical properties, there could be more than 1 such station installed.
Further, for calculation purpose based on its numerical model, parameters such as geographical properties, subsidence parameters such as stress distribution, tensile strain and stability of stope are considered.

The present invention is now illustrated by non-limiting examples:

Example 1:
The experimental work of present invention is carried out at Munsar Mines (Maharashtra, India). The technical details of the experimental site of Munsar Mines (Fig. 1) are given below.

(1) About Munsar Mine:
The Munsar Mine of MOIL Limited is being worked since 1903. The total lease hold area of the mine is 140.49 ha, which includes four leases in Munsar and Chargaon villages. The Munsar Mine is comprises four leases namely 108.63 ha, 25.15 ha, 5.74 ha & 0.97 ha. The mine was located at 79° 16' East longitude and at 21°24' North latitude. The lease area is having forest land. The manganese produced in this mine, presently from the underground & old mineral reject dumps is being dispatched by rail to various Ferro/Silico-manganese industries and steel plants. The details of leased land are as follows:
Table 1
Sr. No. Total Lease Area in Ha. Forest land in lease in Ha.
1. 108.63 12.15
2. 25.15 3.40
3. 5.74 5.72
4. 0.97 0.97
Total 140.49 22.24

Since subsidence observations in India as well as other parts of the world are predominantly related to coal mining areas, subsidence prediction in this case of Munsar Mine is calculated on the basis of coal mining experience in the country.

(2) Geotechnical Details:
Geotechnical engineers and engineering geologists perform geotechnical investigations to obtain information on the physical properties of soil and rock underlying (and sometimes adjacent to) a site to design earthworks and foundations for proposed structures. In this case pillars are erected for which geotechnical details are required to determine the size (height x weight) of each pillar.
Geological parameters of Munsar Mine are given below:
a) Physiography
The area is general plains with intermittent ridges arising out generally in NW-SE trend. The hills are seldom above 90 m from general ground level i.e. 315 m above MSL. However, the altitude of higher points of ridge in 428 m MSL and the lowest plain area altitude in 320 m MSL. North western part of the mine is higher elevation than remaining areas which gradually sloping down to ground level towards southern and eastern of the mine.
b) Drainage Pattern
There are number of non-perennial water courses and nalas originating from the above mentioned ridges from higher slopes of the hill to main drainage system of Kanhan River. The general slope of the surrounding area is towards south-west direction, the general ground level of 315 m MSL. Drainage of the area controlled by seasonal gullies formed due to rain water.
c) Vegetation
The different types of natural vegetation in these area are reflects the topography and under lying lithology. The area around Munsar is largely cultivated, a major part of hills are covered by afforestation. The common trees found to the vicinity of villages are “Neem” (Azadirachata), Tamarind (TamarindusIndica), Pipal, Teak (ShiraTaberxa) grows and in new wide spread planted forests contain mixed growth of Sal (TerminatiaSanentora) Bija (PrsocaspusMarasupum) Bamboo, Dhawra, Lendia (Lagers TroemiaParuflora), Trefdu (DiospyrosMelanPxylan) etc. with scattered ‘Harra’ Mahrea (BassiaLatifolia), Cheer (Buch a namialitiafolia) and Amla which bear edible fruits.

d) Climate
The climate of the area is moderately dry tropical with well-marked dry and wet seasons. The average maximum temperature during summer ranges from 44-46o C while in winter the average temperature ranges from 6-8o C. Monsoon sets in the area by middle of the June. The average yearly rainfall in the area ranges from 1000 mm.

e) Regional Geology

The manganese deposits in the area are associated with rock of Sausar. These rocks are mainly meta-sediments composed of quartzite, various types of schist and gneiss. These are found at the base of the lower most Sausar Series of rock and have been involved in the movements along with the other rocks and thus have develop certain features which make it difficult to identified them from the other rock of the Sausar Series.

Table 2: Geological Succession of “SAUSAR GROUP”
Recent to Sub-recent Soil Laterite & Alluvium.
Post Sausar Pegmatite & Quartz Veins.

S
A
U
S
A
R

G
R
O
U
P Bichua Formation Pink and White dolomite marble containing dioxide, Serpintine, Epidote etc.
Junewani Formation Biotite Granulite and Biotite Schist
Chorbaoli Formation Quartzite, Micaceous Quartzite.
MunsarFormation Muscovite Schist, Muscovite Biotite Schist locally felsphathic as well as quartzose with three Manganese Ore horizon I at the top, horizon II within and horizon III at the base developed at different place.
Lohangi Formation Marbles, Calc Gneisses and Granulities, Epidote Quartzite, Magnetite bearing Biotite Quartz Schist often leticular& containing pockets of Manganese Ore at places.
Lohangi Member Calcitic and Dolomitic marbles.
Utekata Member Calc-silicate granulites and gneisses
KabdiKhera Member Quartz/Biotitegranulites and gneiss.
Sitasaongi Formation Quartz Mica Schist and Quartzite.
-----------------------------Disconformity-------------------
Tirodi Formation Granite Gneiss, Biotite Gneiss, Augen Gneiss and Amphibolite.

f) Other Geo-Technical Details:

The manganese ore horizons of the MUNSAR mine are located in the MUNSAR stage arenaceous schistose rocks and is isoclinals folded into tight anticline and syncline. The manganese ore horizons in the western and central parts are exposed on the higher ground of the MUNSAR hills. The ore horizons are inter-banded with schistose and gneissose rocks, which were part of the original arenaceous-argillaceous sediments, extensively metamorphosed with associated manganiferous sediments. The said gneiss is primarily composed of Quartz, Biotite, Orthoclase and few minor minerals. Arenaceous schistose rocks are extensively developed in the hanging wall side of the ore horizon. The schists are composed of Quartz and Muscovite with some pink coloured Feldspar imparting gneissic appearance. Distinct bands of Quartz schist and Quartzite are present in the schist. The footwall rock consisting of Sillimanite Muscovite Schists, which are mainly composed of Muscovite with some Quartz and Sillimanite, are well foliated. The footwall rock is persistent along entire strike length of the ore body. Impure dolomitic limestone occurs in patches along the western flank in contact with gneissose and schistose rocks. The graphic lithology of a borehole in the mine is shown in Fig. 2.
The compressive strength of the hangwall varied between 15 & 25 Mpa whereas computed Bieniawski’s RMR was about 55. The underground excavation of the ore was carried out in three levels i.e. -270’L, 170’L & 70’L through an incline & below levels -30’L, -130’L, -230’L, -330’L is through vertical shaft sunk at ch.2600. Timber props, chocks and rock bolts are used to support the stopes and hydraulic sand stowing for filling the extraction voids is used. The ore body at the western side of the incline was excavated by opencast mining (Durga I and Durga II pits) only upto a depth of 20m. The area below the opencast quarry is virgin and no underground work has been carried out in the area. The opencast mining is presently stopped and both the pits are being filled by the waste material available from dump mining. The ore body below the opencast quarry is geological continuity of the area excavated by underground mining at the eastern part of the incline. The unexploited ore body thickness below the Durga I and Durga II pits varies from 1-7m with an average of 3m, dip varying from 65-70°. Details is given in Fig.3

(3) Ore body:
For determining geotechnical parameters, detailed engineering geological mapping was carried out and geotechnical parameters were collected from 70’ level. At this level the general strike direction of the ore body is East-West (N70°W-S70°E) and the dip varies from 60° to 70° due N20°E. The ore body is being mined along the strike and dip. Both the hangwall and the footwall consist of quartz mica schist, whereas at some places both hangwall and footwall are consisting of mica schist. Ore body is discontinuous and width of the ore body is also not uniform, and it varies from 5.0 m to 7.0 m with bulging and pinching. The Geological cross section of the winze at 70’L is given below in Fig.4.
The ore body exhibits well-developed bedding or relict stratification marked by alternate bands of spessattite, rhodonite, and manganese ores. Numerous quartz veins intersect the ore body and the wall rocks. The thickness of the individual bands varies from 2 cm to 30 cm. Bedding is also well developed in quartz mica schist/quartzite, whereas bedding planes are extremely rare in mica schist. Schistocity is well developed in schist of MUNSAR Formations throughout the area. The bedding/ foliation plane has a general east-west strike and steep northern dip. Lineation made up by parallel arrangement of platy and prismatic grains such as micas and hornblende, and also of the elongated grains of quartz and feldspar is commonly observed. The ore is hard, and is siliceous in nature. The contact between the ore body and the mica schist is incompetent, whereas the contact between the ore body with quartz mica schist is competent. The ore body occurs with contact of similar wall rocks, i.e., quartz mica schist and also with different wall rocks, i.e., mica schist and quartz mica schist.

(4) Foot wall and Hang wall Rocks
The hanging wall formation occuring to the north of the ore body consists of quartz - mica schist which changes to schistose gneiss due to textural composition and different mineralogical assemblages caused due to metamorphism. In some places the rock contains large bands of quartzite and thus it often looks like quartzitic schistose gneiss/ quartzose gneiss particularly between Ch. 2700 to 3650. The feldespar in the pink schistose gneiss is highly weathered which makes the entire formation soft and brittle. Another formation i.e. pure and impure dolomitic limestone has been found to occur in patches along the western flank of main Munsar hill (north of 170’ L adit from Ch.600 to Ch. 1200.)
The footwall rock to the south of the ore zone is muscovite hard; well foliated and comprises of less quartz & is muscovite sillimanite schist. The rock is marker horizon for ore zone all along the strike of the Munsar deposit. At places the rock looks like asericitic schist (Ch. 2700 to Ch. 3600) in main hill underground section and this may be due to metamorphism.

(5) Prediction for Munsar Mine from literature survey:
As the mine is going in dip direction, surface subsidence will be reduced. The surface subsidence is predicted up to 50 m of depth in the underground mines where post mining filling is being used and in Indian coal mines it is predicted up to 68 m to 165 m , where stowing is eliminated. As method of mining is going below the 123 m at Munsar mine and stope are filled tightly with sand. It is assumed that occurrence of surface subsidence at Munsar Mine in forest cover will be minimal.

Experiment 1:
In the present invention, the 3D model comprises of total 7 pillars, out of which 5 pillars are erected according to east, west, north south and a mid point direction (Fig 4a, 4b). The remaining 2 pillars are subsidence pillars (SP) namely SPI and SPII, both of them are placed at a distance of at least 1 meter apart. This distance depends upon geographical properties of that location. Readings of these 5 pillars are taken with respect to SPI and same is repeated with SPII (Fig. 5a, 5b). Once the readings are recorded, readings with respect to SPI are compared with the reading with respect to SPII. The difference between the readings is considered for micro analysis calculations.

Numerical Modelling & Results:
Based on the monitoring data collected over a period of time, computations are carried out with the help of numerical modeling. To measure the stability of the stope, a 2-dimensional numerical modeling is performed. The considered model geometry is shown in Figure 6. The stope cross section at the maximum width is taken for simulation.

The model is created to examine the stability of the stope when the entire stope is excavated and the back fill is in place. To be on conservative side, maximum width of the stope is considered for the modeling purpose. All the material properties for the model are taken from the tested data. For the purpose of insitu stress conditions, vertical loading was calculated for vertical stresses and the horizontal stresses were taken as twice the vertical stresses. The cut and fill sequence as practiced in the mine is simulated. Rock bolts of 1.5m long are installed with 2m spacing as practiced in the mine. The condition of the roof after 4 lifts is shown in Figure 7.
The maximum induced stress due to mining is of the order of 23.00MPa for this stage. This induced stress is very minimal when compared to the rock mass strength thus not posing any instability problems in the stope during the stoping operation.
The stress distribution around the crown pillar and sides of the stope after full stope is excavated and backfilled is placed in Figure 9. The maximum induced stress due to mining is of the order of 30.00MPa for this stage. This induced stress is not significant when compared to the rock mass strength and hence the stability of the crown pillar is achieved with the designed thickness.
From the modelling the present roof support of timber props, chocks and roof bolt with designated barrier pillar thickness of 5 m is sufficient. The stopes are filled with sand hydraulically and hence it is suggested that no subsidence may happened on the surface.

Estimation of Subsidence Parameters
Considering the values of strength, RMR for hangwall, footwall & ore body, the hangwall rocks are comparable with the softer version of coal measure rocks. Since subsidence observations in India as well as other parts of the world are predominantly related to coal mining areas, subsidence prediction in this case is calculated on the basis of coal mining experience in the country.

It is necessary to define the following subsidence terms for a better understanding of the report:

1) Non-effective width of extraction (NEW): This is the maximum width of an excavation up to which no subsidence on the surface takes place.

2) Critical width of extraction (CW): This is the width of an excavation at which the subsidence attains its maximum value. Any further increase in the extraction width beyond this value does not increase the subsidence. The critical width in India is about 3.5 times NEW. Any width of extraction less than the critical width but greater than NEW is the sub-critical width of extraction (SW).

3) Maximum possible subsidence (Smax): This is the value of subsidence, which takes place at the critical width of extraction and beyond.

4) Subsidence Factor (SF): This is the ratio of the Smax and the extraction thickness.

The following data have been used for subsidence calculation (refer Fig.2):

Depth of the middle of the stope from the surface (off the filling), H= 40m.

a) Inclined stope height (extraction width for the purpose of subsidence calculation W = 20 / sin 70° = 21.27 m.
b) Maximum extraction thickness, M = 7 m
c) Width to depth ratio, W/H = 21.27 / 40= 0.532

Subsidence Monitoring at Munsar Mine:
Subsidence monitoring station has been installed at forest area of eastern and western side of the lease area. Established subsidence monitoring stations for 3-D recording of x, y, z coordinates (Northing/ Latitude Y (m, Easting / Departure X (m) and Elevation / RL Z (m) is continuously monitored from last 3 years. Location plan of measuring stations for subsidence at Munsar Mine in Forest Land is shown in Fig. 8. Latitude, longitude and reduce levels are being measured by total station and monitored quarterly in dip and strike direction for real time monitoring of the subsidence movement. Moreover, the distance between the consecutive points of subsidence stations is also monitored quarterly and it will be verified annually by the research / academic institutions for their recommendations.

Subsidence Monitoring Station in Forest Land:
Monitoring stations with subsidence points has been properly erected in the forest area and quarterly measurement is being done by total station to monitor the 3-D coordinates. Photographs of the measuring pillar of subsidence BP-50 & BP-70 was located in west side and east side respectively.
The following instrument has been used during the quarterly monitoring of subsidence:
Table 3
Name of the instrument Least count Accuracy
For horizontal and vertical control (x,y,z coordinates) –Total station of Timber make Angle – 1”
Linear – 1mm +3”
+/- 5 mm

Since the method of stoping is proposed to be cut and fill, the observations over stowed panels are used. The subsidence factor (SF) for well-stowed panels in India ranges between 0.02 and 0 .05, and the value of ratio NEW/H in India ranges between 0.3 and 0.8, the lower bound values occurring in softer strata. Therefore, in the case of MUNSAR we may adopt NEW/H value as 0.3. The width to height ratio at MUNSAR is found to be 0.532, which is much less than the CW/H (1.05 in this case) but more than the NEW/H and as such is sub-critical. Because of the gradient of the ore body, the filling of the stope is expected to be very tight and therefore the lower bow value of the subsidence factor may safely be taken in this instance. Further as the panel is sub-critical, the maximum subsidence (S) that may be anticipated will be:
S = 0.01 M = 0.01 x 7 = 70 mm
The value of S (70 mm) is to be substituted in the following relations:
Maximum slope of subsidence (G) = 2.0 S/H = 3.5 mm/m
Maximum compressive strain (E-) = 1.1 S/H = 1.925 mm/m
Maximum tensile strain (E+) = 1.0 S/H = 1.75 mm/m
The above values are not expected to cause any surface damage as per following Table 1.

Table 4 – Safe limits of subsidence for various properties in India (Saxena and Singh,
1989)

Type of property Safe tensile strain Slope Elongation
Railway line 3 mm/m 10 mm/m -
Water bodies 4.5 mm/m - -
Building - - 60 mm
Aerial ropeway 3 mm/m - -
Forest land 20 mm /m - -

The following instrument has been used during the quarterly monitoring of subsidence:
Table 5
Name of the instrument Least count Accuracy
For horizontal and vertical control (x,y,z coordinates) –Total station of Trimbe make Angle – 1”
Linear – 1mm +3”
+/- 5 mm

TRAIL RESULTS:
MOIL LIMITED
MUNSAR MINE
Table 7: SUBSIDENCE SURVEY RECORD
LOCATION:- MEO DUMP (WEST SIDE OF LEASE AREA)

SL.No. STATION CO-ORDINATE R.L.in Mtrs. REMARK
LOG. LAT.
1 SP-I 21°-24'-17.5'' 79°-16'-33.9'' 360.005 Initial Readings
2 SP-II 21°-24'-17.3'' 79°-16'-33.9'' 360.129 Initial Readings
3 W-1 21°-24'-17.3'' 79°-16'-34.0'' 359.955 Initial Readings
4 M-1 21°-24'-17.3'' 79°-16'-34.1'' 359.951 Initial Readings
5 E-1 21°-24'-17.3'' 79°-16'-34.2'' 359.948 Initial Readings
6 N-1 21°-24'-17.3'' 79°-16'-34.1'' 359.951 Initial Readings
7 S-1 21°-24'-17.2'' 79°-16'-34.2'' 359.945 Initial Readings

Table 8: SUBSIDENCE SURVEY YEAR -2014-15
LOCATION:- MEO DUMP (WEST SIDE OF LEASE)- April – June, 2014
1St Quarter 1ST
SL.No. STATION R.L. IN Mtrs.

1 SP-I 360.005
2 SP-II 360.129
3 W-1 359.955
4 M-1 359.951
5 E-1 359.948
6 N-1 359.951
7 S-1 359.945

Table 9: SUBSIDENCE SURVEY YEAR -2014-15
LOCATION:- MEO DUMP (WEST SIDE OF LEASE) – Oct-Dec, 2014

3RD QUARTER
SL.No. STATION R.L. IN Mtrs.

1 SP-I 360.004
2 SP-II 360.129
3 W-1 359.954
4 M-1 359.950
5 E-1 359.948
6 N-1 359.952
7 S-1 359.945

Table 10: SUBSIDENCE SURVEY YEAR -2014-15
LOCATION:- MEO DUMP (WEST SIDE OF LEASE)- July-Sept, 2014
2ND QUARTER
SL.No. STATION R.L. IN Mtrs.

1 SP-I 360.006
2 SP-II 360.130
3 W-1 359.954
4 M-1 359.951
5 E-1 359.947
6 N-1 359.950
7 S-1 359.945

Table 11: SUBSIDENCE SURVEY YEAR -2014-15
LOCATION:- MEO DUMP (WEST SIDE OF LEASE) – Jan-March, 2015
4TH QUARTER
SL.No. STATION R.L. IN Mtrs.

1 SP-I 360.005
2 SP-II 360.128
3 W-1 359.955
4 M-1 359.951
5 E-1 359.949
6 N-1 359.951
7 S-1 359.945

Table 12: SUBSIDENCE SURVEY YEAR -2015-16
LOCATION:- MEO DUMP (WEST SIDE OF LEASE) – April-June, 2015

1ST-QUARTER
SL.No. STATION R.L. IN Mtrs.

1 SP-I 360.006
2 SP-II 360.130
3 W-1 359.954
4 M-1 359.952
5 E-1 359.948
6 N-1 359.950
7 S-1 359.946

Table 13: SUBSIDENCE SURVEY YEAR -2015-16
LOCATION:- MEO DUMP (WEST SIDE OF LEASE) – July-Sept, 2015
2ND-QUARTER
SL.No. STATION R.L. IN Mtrs.

1 SP-I 360.006
2 SP-II 360.130
3 W-1 359.954
4 M-1 359.951
5 E-1 359.948
6 N-1 359.950
7 S-1 359.946

Table 14: SUBSIDENCE SURVEY YEAR -2015-16
LOCATION:- MEO DUMP (WEST SIDE OF LEASE) – Oct-Dec, 2015
3RD-QUARTER
SL.No. STATION R.L. IN Mtrs.

1 SP-I 360.005
2 SP-II 360.129
3 W-1 359.954
4 M-1 359.950
5 E-1 359.947
6 N-1 359.951
7 S-1 359.945

Table 15: SUBSIDENCE SURVEY YEAR -2015-16
LOCATION:- MEO DUMP (WEST SIDE OF LEASE) – Jan-March, 2016
4TH-QUARTER
SL.No. STATION R.L. IN Mtrs.

1 SP-I 360.006
2 SP-II 360.128
3 W-1 359.954
4 M-1 359.950
5 E-1 359.949
6 N-1 359.952
7 S-1 359.946
Table 16: SUBSIDENCE SURVEY YEAR -2016-17
LOCATION:- MEO DUMP (WEST SIDE OF LEASE) – April-June, 2016
1ST-QUARTER
SL.No. STATION R.L. IN Mtrs.

1 SP-I 360.008
2 SP-II 360.131
3 W-1 359.955
4 M-1 359.952
5 E-1 359.948
6 N-1 359.951
7 S-1 359.945

Table 17: SUBSIDENCE SURVEY YEAR -2016-17
LOCATION:- MEO DUMP (WEST SIDE OF LEASE)- July-Sept, 2016

2ND-QUARTER
SL.No. STATION R.L. IN Mtrs.

1 SP-I 360.007
2 SP-II 360.130
3 W-1 359.954
4 M-1 359.952
5 E-1 359.948
6 N-1 359.950
7 S-1 359.976

Table 18: SUBSIDENCE SURVEY YEAR -2016-17
LOCATION:- MEO DUMP (WEST SIDE OF LEASE) – Oct-Dec, 2016
3RD-QUARTER
SL.No. STATION R.L. IN Mtrs.

1 SP-I 360.006
2 SP-II 360.130
3 W-1 359.955
4 M-1 359.951
5 E-1 359.948
6 N-1 359.951
7 S-1 359.945
Table 19: SUBSIDENCE SURVEY YEAR -2016-17
LOCATION:- MEO DUMP (WEST SIDE OF LEASE) – Jan-March, 2017
4TH-QUARTER
SL.No. STATION R.L. IN Mtrs.

1 SP-I 360.006
2 SP-II 360.129
3 W-1 359.955
4 M-1 359.951
5 E-1 359.949
6 N-1 359.951
7 S-1 359.945

Table 20: SUBSIDENCE SURVEY YEAR -2017-18
LOCATION:- MEO DUMP (WEST SIDE OF LEASE) – April-June, 2017
1ST-QUARTER
SL.No. STATION R.L. IN Mtrs.

1 SP-I 360.006
2 SP-II 360.133
3 W-1 359.955
4 M-1 359.951
5 E-1 359.949
6 N-1 359.951
7 S-1 359.944

Table 21: SUBSIDENCE SURVEY YEAR -2017-18
LOCATION:- MEO DUMP (WEST SIDE OF LEASE) – July-Sept, 2017
2ND-QUARTER
SL.No. STATION R.L. IN Mtrs.

1 SP-I 360.007
2 SP-II 360.131
3 W-1 359.955
4 M-1 359.95
5 E-1 359.948
6 N-1 359.950
7 S-1 359.975

MOIL LIMITED
MUNSAR MINE
Table 22: SUBSIDENCE SURVEY RECORD AT FOREST LAND NEAR 2ND SHAFT

LOCATION:- NEAR 2ND VERTICAL SHAFT (EAST SIDE OF LEASE AREA)

SL.No. STATION CO-ORDINATE R.L. IN Mtrs. REMARK
LOG. LAT.
1 SP-I 21°-23'-51.8'' 79°-17'-25.9'' 329.478 Initial Record
2 SP-II 21°-23'-51.8'' 79°-17'-25.8'' 329.469 Initial Record
3 E-II 21°-23'-51.8'' 79°-17'-25.6'' 329.517 Initial Record
4 M-II 21°-23'-51.8'' 79°-17'-25.5'' 329.475 Initial Record
5 W-II 21°-23'-51.7'' 79°-17'-25.5'' 329.489 Initial Record
6 N-II 21°-23'-51.8'' 79°-17'-25.5'' 329.499 Initial Record
7 S-II 21°-23'-51.7'' 79°-17'-25.6'' 329.487 Initial Record

Table 23: SUBSIDENCE SURVEY YEAR -2014-15
LOCATION:-NEAR 2ND VERTICAL SHAFT (EAST SIDE OF LEASE)- April-June,2014
1ST QUARTER
SL.No. STATION R.L. IN Mtrs.

1 SP-I 329.478
2 SP-II 329.469
3 W-II 329.517
4 M-II 329.475
5 E-II 329.489
6 N-II 329.499
7 S-II 329.487

Table 24: SUBSIDENCE SURVEY YEAR –
2014-15
LOCATION:-NEAR 2ND VERTICAL SHAFT (EAST SIDE OF LEASE)- July-Sept,2014
2ND QUARTER
SL.No. STATION R.L. IN Mtrs.

1 SP-I 329.477
2 SP-II 329.468
3 W-II 329.519
4 M-II 329.476
5 E-II 329.488
6 N-II 329.498
7 S-II 329.489

Table 25: SUBSIDENCE SURVEY YEAR -2014-15
LOCATION:-NEAR 2ND VERTICAL SHAFT (EAST SIDE OF LEASE)-Oct-Dec, 2014
3RD QUARTER
SL.No. STATION R.L. IN Mtrs.

1 SP-I 329.479
2 SP-II 329.469
3 W-II 329.518
4 M-II 329.476
5 E-II 329.487
6 N-II 329.500
7 S-II 329.487

Table 26: SUBSIDENCE SURVEY YEAR -2014-15
LOCATION:-NEAR 2ND VERTICAL SHAFT (EAST SIDE OF LEASE)-Jan-March,2015
4TH QUARTER
SL.No. STATION R.L. IN Mtrs.

1 SP-I 329.479
2 SP-II 329.470
3 W-II 329.517
4 M-II 329.475
5 E-II 329.488
6 N-II 329.499
7 S-II 329.488

Table 27: SUBSIDENCE SURVEY YEAR -2015-16
LOCATION:-NEAR 2ND VERTICAL SHAFT (EAST SIDE OF LEASE)
April-June,2015 1ST-QUARTER
SL.No. STATION R.L. IN Mtrs.

1 SP-I 329.480
2 SP-II 329.467
3 W-II 329.516
4 M-II 329.475
5 E-II 329.488
6 N-II 329.497
7 S-II 329.489

Table 28: SUBSIDENCE SURVEY YEAR
-2015-16
LOCATION:-NEAR 2ND VERTICAL SHAFT (EAST SIDE OF LEASE)
July – Sept, 2015 2ND-QUARTER
SL.No. STATION R.L. IN Mtrs.

1 SP-I 329.478
2 SP-II 329.469
3 W-II 329.518
4 M-II 329.474
5 E-II 329.488
6 N-II 329.497
7 S-II 329.488

Oct- Dec, 2015 3RD-QUARTER
SL.No. STATION R.L. IN Mtrs.

1 SP-I 329.479
2 SP-II 329.468
3 W-II 329.518
4 M-II 329.475
5 E-II 329.489
6 N-II 329.498
7 S-II 329.487
Jan – March, 2016 4TH-QUARTER
SL.No. STATION R.L. IN Mtrs.

1 SP-I 329.477
2 SP-II 329.469
3 W-II 329.517
4 M-II 329.476
5 E-II 329.488
6 N-II 329.499
7 S-II 329.489

Table 29: SUBSIDENCE SURVEY YEAR -2016-17
LOCATION:-NEAR 2ND VERTICAL SHAFT (EAST SIDE OF LEASE) – April-June,16
1ST-QUARTER
SL.No. STATION R.L. IN Mtrs.

1 SP-I 329.478
2 SP-II 329.469
3 W-II 329.518
4 M-II 329.475
5 E-II 329.489
6 N-II 329.499
7 S-II 329.487

Table 30: SUBSIDENCE SURVEY YEAR -2016-17
LOCATION:-NEAR 2ND VERTICAL SHAFT (EAST SIDE OF LEASE)-July-Sept,2016
2ND-QUARTER
SL.No. STATION R.L. IN Mtrs.

1 SP-I 329.477
2 SP-II 329.468
3 W-II 329.516
4 M-II 329.476
5 E-II 329.490
6 N-II 329.499
7 S-II 329.486
Table 31: SUBSIDENCE SURVEY YEAR -2016-17
LOCATION:-NEAR 2ND VERTICAL SHAFT (EAST SIDE OF LEASE)-Oct-Dec,2016
3RD-QUARTER
SL.No. STATION R.L. IN Mtrs.

1 SP-I 329.476
2 SP-II 329.467
3 W-II 329.517
4 M-II 329.474
5 E-II 329.488
6 N-II 329.499
7 S-II 329.487

Table 32: SUBSIDENCE SURVEY YEAR -2016-17
LOCATION:-NEAR 2ND VERTICAL SHAFT (EAST SIDE OF LEASE)-Jan-Mrach,2017
4TH-QUARTER
SL.No. STATION R.L. IN Mtrs.

1 SP-I 329.477
2 SP-II 329.468
3 W-II 329.518
4 M-II 329.476
5 E-II 329.489
6 N-II 329.499
7 S-II 329.487

Table 33: SUBSIDENCE SURVEY YEAR -2017-18
LOCATION:-NEAR 2ND VERTICAL SHAFT (EAST SIDE OF LEASE)-April-June,2017
1ST-QUARTER
SL.No. STATION R.L. IN Mtrs.

1 SP-I 329.479
2 SP-II 329.468
3 W-II 329.516
4 M-II 329.476
5 E-II 329.488
6 N-II 329.498
7 S-II 329.486
Table 34: SUBSIDENCE SURVEY YEAR -2017-18
LOCATION:-NEAR 2ND VERTICAL SHAFT (EAST SIDE OF LEASE), July-Sept,2017
2ND-QUARTER
SL.No. STATION R.L. IN Mtrs.

1 SP-I 329.478
2 SP-II 329.467
3 W-II 329.517
4 M-II 329.476
5 E-II 329.487
6 N-II 329.498
7 S-II 329.487

Advantages of Present Invention:
1. The principal finding of the present invention is the station having such 7 pillar model is critical for such micro-level determination of subsidence of the location under mining.
2. This method is more accurate than the monitoring method done by using GPS or remote sensing like Hi-Tech utilities.
3. This method not only saves time and money, but also increases overall accuracy in prediction.
4. This method helps in computing tensile strains and minimizing the subsidence in forest cover area.

We claim,
1. A method used to determine the subsidence of a location under mining site comprising the steps of

i) providing an arrangement of seven pillars wherein five pillars comprises first boundary pillar, second boundary pillar, third boundary pillar, fourth boundary pillar and fifth boundary pillar wherein the fifth pillar being directed to the middle of the boundary pillars and two pillars comprises first subsidence pillar and second subsidence pillar wherein the subsidence pillars being placed so as to get the distance of at least 1 meter apart.
ii) taking a reading of the boundary pillars with respect to first subsidence pillar and the reading as obtained is recorded;
iii) taking a reading of the boundary pillars with respect to second subsidence pillar and the reading as obtained is recorded;
iv) comparing the readings;
wherein the pillars are vertically arranged.

Dated this 21st day of November, 2018

(Dr. Ushoshi Guha)
Patent Agent (IN/PA 720)
Of Lex-Regia
For the Applicant

ABSTRACT
“A METHOD USED TO DETERMINE THE SUBSIDENCE AT A MINING SITE”
Disclosed is A method used to determine the subsidence of a location under mining site comprising the steps of providing an arrangement of seven pillars wherein five pillars comprises first boundary pillar, second boundary pillar, third boundary pillar, fourth boundary pillar and fifth boundary pillar wherein the fifth pillar being directed to the middle of the boundary pillars and two pillars comprises first subsidence pillar and second subsidence pillar wherein the subsidence pillars being placed so as to get the distance of at least 1 meter apart; taking a reading of the boundary pillars with respect to first subsidence pillar and the reading as obtained is recorded; taking a reading of the boundary pillars with respect to second subsidence pillar and the reading as obtained is recorded; comparing the readings wherein the pillars are vertically arranged. Figure 5(a) & 5(b)