WO2016115816A1 - Structural discrimination indexes of ordovician limestone top filling zones and determination method - Google Patents

Abstract

Structural discrimination indexes of an ordovician limestone top filling zone and a determination method, coal field-based ordovician limestone top filling zones of a buried depth of more than 300 m, according to structural discrimination indexes of the drilling unit water inflow q value, the underground drilling dewatering test Q value and the penetration test K value, are divided into three types of the ordovician limestone top water-resisting filling zones: a water-resisting filling zone, a weak water-resisting filling zone and a water-enriched zone. The water-resisting filling zone can be directly used as a water-resisting layer, the weak water-resisting filling zone can be used after having been improved into the water-resisting layer by grouting. The structural discrimination indexes of the method are obtained from conventional hydrological tests, and the method is relatively simple to obtain and easy to operate by field staffs.

Description

Discriminating index and determination method of top filling belt of ash Technical field

The invention relates to a water-bearing geological structure discriminating index and a determining method, in particular to a discriminating index and a determining method for an ash top filling belt structure.

Background technique

Ordovician limestone has always been a strong aquifer in the area of coal-bearing coalfields in North China, and it is the main target of the threat of water pollution in the next group of coal mining. And as the depth of mining increases, the water pressure increases and the danger becomes greater and greater. It is estimated that China's North China coalfield is threatened by deep high-pressure Ordovician water (the water inrush coefficient is greater than 0.1MPa/m) with a coal geological reserve of about 15 billion tons. Therefore, how to realize the lower coal seam pressure belt mining and reduce the mining cost is the goal of exploration in the North China coal field in recent years.

Before the new century, scholars focused on the risk assessment of the ash water inrush and the mechanism of water inrush in the next group of coal mining, ignoring the top of the Ordovician limestone as the paleo-weathering crust, its geological structure and filling characteristics. Many mines (zones) can be used as a water barrier and a weak (permeable) water layer (suitable for grouting into a water barrier). Since the new century, with the mining depth of some mines in the North China coalfield, the critical value of the ash water inrush coefficient has been approached, which results in a large part of the lower coal group with a large depth of burial cannot be released. How to achieve safe mining of the next group of coals has become a problem at this stage. Based on a large number of on-site pumping (discharge) water tests, it is indicated that some of the boreholes have little or no water when they first enter the ash, indicating that the top of the ash is a low-permeability medium, which can be directly used as a water-repellent layer. The on-site pumping and water-discharging tests also showed that some of the boreholes had a medium water output when entering the top of the ash, or the water output was indistinguishable from the underlying ash-grey aquifer, indicating that the permeability of the filling belt is quite different and cannot be generalized. The water barrier is used. From the perspective of seepage control of rock mass structure, it is considered that the belt structure is the key factor to control the different permeability of the filling belt.

The type division of the top filling belt of the ash and its water-repellent utilization have been gradually recognized and confirmed by a few mining practice mines. However, how to determine the type of filling belt is mainly based on the method of drilling core observation and fracture statistics, and the types of filling belts are roughly and qualitatively divided. The subjective factors are large, and the quantitative index determination method is lacking.

Summary of the invention

The object of the present invention is to provide a discriminating index and determining method for the top filling belt structure of the ash, and to solve the observation and description of the drilling core, the statistical method of the crack, and the type of the filling belt, and the subjective factors are large, and the quantitative index is determined. Method problem.

The object of the present invention is achieved as follows: the present invention includes a structure discrimination index and a structure determination method;

I. The structure discriminating index: Firstly, the three filling belt structures of continuous filling, intermittent filling and non-filling are determined. According to the three filling belt structures, the discriminating indexes are determined as follows: drilling unit water inflow q, downhole water discharge Q and Austrian The permeability coefficient of the gray layer segment is K; then the threshold values of each index are determined according to the different water-blocking properties of the three structures;

The indicators are obtained by the following methods, as follows:

1. Firstly, a large number of samples of the outcrop of the filling belt are taken to investigate the filling of the shale filled with cracks, and the filling belt is filled according to the degree of filling of the crack, which can be identified as: continuous filling, intermittent filling and no filling. Structure; the types of filling belts corresponding to the three types of filling belt structures are water-blocking type, weakly permeable type and water-rich type;

2. When the depth of the filling belt is more than 300m, the three indicators of the filling belt structure are determined according to the pumping and discharging experiments, namely: the water inflow amount q of the drilling unit, the water discharge amount Q in the underground and the permeability coefficient K in the Austrian ash layer;

2-1. Acquisition of the water inflow unit q index of the drilling unit: The ground drilling is based on the core take-up rate, the flushing fluid consumption and the degree of shale development, and comprehensively determine the development termination depth of the filling belt; determine the lithology adoption rate is less than 50%. The depth of the shale development is the depth of development of the filling zone; thus, the interval of the pumping test is determined to be the interval from the entry of the ash to the depth, and the q value of the interval is calculated according to formula (1);

Where, Q is the well flow, m3/s; M is the thickness of the pumping interval, m; sw is the depth of the water level in the well, m; R is the radius of influence, m; rw is the radius of the pumping well, m;

2-2. Acquisition of Q indicator for underground water discharge: The water discharge test is carried out on the underground drilling hole, and the water discharge amount of the interval is recorded every 2m; for the previous underground water discharge test without such large density record, the recorded water discharge amount Q , the fitting analysis is carried out, and the fitting formula of a certain water drainage hole is used for description, and the formula (2) is obtained from the water discharge amount of each depth entering the Austrian ash;

Q=63.56ln(x)-483.8 (2)

Where x is the depth of entering the ash, m; Q enters the water inflow to the depth of the ash, m ³ / s;

2-3. Acquisition of permeability coefficient K: The water discharge test is carried out on the underground drilling hole, and the stable water pressure P _{1 of} each interval and the instantaneous water pressure P ₂ when the valve is closed during the discharge process are recorded respectively, that is, the interval is represented. The water pressure value during the water discharge test, calculate the actual deepening value S during the water discharge process, and calculate the permeability coefficient K of the interval according to formula (3) (4);

Where K is the permeability coefficient, cm/s; other parameters have the same meaning as formula (1);

3. The method for determining the threshold value of the water inflow unit q index, the downhole water release Q index and the permeability coefficient K index, the specific steps are as follows:

3-1. Determine the threshold value of the water inflow unit q of the drilling unit: Because the continuous filling structure is water-proof, when q<0.001L/sm in the pumping test, the pumping interval will be water-tight, and q<0.001L/sm is determined. The interval is a water-filled filling belt; because the intermittent filling structure is weakly permeable, when the pumping test is 0.001<q<0.01L/sm, the pumping interval is weakly permeable, and 0.001<q<0.01L/sm is determined. The layer is a weakly permeable filling belt; because the unfilled structure is rich in water, when the pumping test is q>0.01L/sm, the pumping interval is rich in water, and the interval of q>0.01L/sm is determined to be rich in water. Type filling belt;

3-2. Determining the threshold of the amount of water released in the well: The water richness of the structure of the filling belt is the same as that of the 3-1 step. The threshold of the Q threshold determined by the step 1 and the depth of the buried depth is greater than the average depth of the 300 m, and the threshold of Q is obtained; The location of the coal with a depth of more than 300m is determined, and the water pressure value of the ash is determined to be 4 levels, which are 3MPa, 4MPa, 5MPa, 6MPa respectively, and the water level drop in the pumping and discharging test is assumed to be the maximum depth, ie 300m, 400m, 500m, 600m respectively; The threshold of the amount of water in the hole;

3-3. Determining the threshold of the permeability coefficient K: The water-rich structure of the filling belt is the same as the 3-1 step. When the permeability coefficient is K<10 ^-5 cm/s in the pumping test, the test interval is water-tight, and the K is determined. <10 ^-5 cm/s is a water-filling type filling belt; when the permeability coefficient is 10 ^-5 <K<10 ^-4 cm/s in the pumping test, the test interval is weakly permeable, and it is determined that 10 ^-5 <K<10 ^-4 cm/s is a weakly permeable filling belt; in the pumping test, when the permeability coefficient is K>10 ^-4 cm/s, the test interval is rich in water, and it is determined that K>10 ^-4 cm/s is water-rich. Filling tape

Second, the specific steps of the structure determination method are as follows:

1. According to the above evaluation index and its threshold value, comprehensively determine the type of filling belt and the thickness of each type. For the water-proof filling belt, it can be directly used as the water-repellent layer; for the weak-permeable filling belt, after the grouting transformation It is used; the water-rich filling belt has the same permeability as the underlying ash, and cannot be used as a water-repellent layer;

2. Draw the contour map of the thickness of the water-proof filling belt, the contour map of the water inrush coefficient of the water-proof filling belt, and the contour map of the water inrush coefficient of the water-blocking filling belt; The contour map is compared and analyzed to determine the safe mining area of the next group of coal.

The beneficial effect, because the above scheme is adopted, the structural discriminant index of the filling belt is given, which makes up for the problem that the filling belt is not easy to identify when the depth of the buried depth is more than 300m, that is, the large depth of the North China coal field; and the indicators are given. The structural threshold gives the quantitative standard of each structure of the filling belt, which solves the problem of large subjectivity caused by the experience only to determine the filling belt. The water-proof filling belt determined by the invention can be directly used as the water barrier. The layer is used; for the weakly permeable filling belt, it can be used after grouting and transformation; the water-rich filling belt has the same permeability as the underlying ash, and can not be used as the aquifer; for the depth of the buried depth is more than 300m, that is, North China Technical support is provided for the coal mining under the coal mining area to achieve safe mining using the filling belt.

Advantages: The structural discriminating indexes proposed by the present invention are all obtained from conventional hydrological experiments, and the obtaining method is relatively simple, and is easy for field personnel to operate, and is convenient for field application practice. The given structural discriminant index and threshold value are applicable to the filling belt of North China coalfield, and the scope of application is wide, and the application prospect is broad.

BRIEF DESCRIPTION OF THE DRAWINGS:

1 is a schematic view showing the structure of the top filling belt of the Ordovician according to the present invention and its water-rich property.

2 is a method for determining a structural index of a filling belt according to the present invention.

3 is a contour map of the thickness of the top filling belt of the ash in the Baodian coal mine according to an embodiment of the present invention.

4 is a distribution diagram of the water inrush coefficient of the coal ash of the Baodian coal mine in the embodiment of the present invention.

FIG. 5 is a distribution diagram of the water inrush coefficient of the 17 coal plus filling belt in the Baodian coal mine of the embodiment of the present invention.

detailed description

The invention includes a structure discrimination index and a structure determination method;

I. The structure discriminating index: Firstly, the three filling belt structures of continuous filling, intermittent filling and non-filling are determined. According to the three filling belt structures, the discriminating indexes are determined as follows: drilling unit water inflow q, downhole water discharge Q and Austrian The permeability coefficient of the gray layer segment is K; then the threshold values of each index are determined according to the different water-blocking properties of the three structures;

The indicators are obtained by the following methods, as follows:

1. Firstly, a large number of samples of the outcrop of the filling belt are taken to investigate the filling of the shale filled with cracks, and the filling belt is filled according to the degree of filling of the crack, which can be identified as: continuous filling, intermittent filling and no filling. Structure; the types of filling belts corresponding to the three types of filling belt structures are water-blocking type, weakly permeable type and water-rich type;

2. When the depth of the filling belt is more than 300m, the three indicators of the filling belt structure are determined according to the pumping and discharging experiments, namely: the water inflow amount q of the drilling unit, the water discharge amount Q in the underground and the permeability coefficient K in the Austrian ash layer;

2-1. Acquisition of the water inflow unit q index of the drilling unit: The ground drilling is based on the core take-up rate, the flushing fluid consumption and the degree of shale development, and comprehensively determine the development termination depth of the filling belt; determine the lithology adoption rate is less than 50%. The depth of the shale development is the depth of development of the filling zone; thus, the interval of the pumping test is determined to be the interval from the entry of the ash to the depth, and the q value of the interval is calculated according to formula (1);

Where, Q is the well flow, m3/s; M is the thickness of the pumping interval, m; sw is the depth of the water level in the well, m; R is the radius of influence, m; rw is the radius of the pumping well, m;

2-2. Acquisition of Q indicator for underground water discharge: The water discharge test is carried out on the underground drilling hole, and the water discharge amount of the interval is recorded every 2m; for the previous underground water discharge test without such large density record, the recorded water discharge amount Q , the fitting analysis is carried out, and the fitting formula of a certain water drainage hole is used for description, and the formula (2) is obtained from the water discharge amount of each depth entering the Austrian ash;

Q=63.56ln(x)-483.8 (2)

Where x is the depth of entering the ash, m; Q enters the water inflow to the depth of the ash, m ³ / s;

2-3. Acquisition of permeability coefficient K: The water discharge test is carried out on the underground drilling hole, and the stable water pressure P _{1 of} each interval and the instantaneous water pressure P ₂ when the valve is closed during the discharge process are recorded respectively, that is, the interval is represented. The water pressure value during the water discharge test, calculate the actual deepening value S during the water discharge process, and calculate the permeability coefficient K of the interval according to formula (3) (4);

Where K is the permeability coefficient, cm/s; other parameters have the same meaning as formula (1);

3. The method for determining the threshold value of the water inflow unit q index, the downhole water release Q index and the permeability coefficient K index, the specific steps are as follows:

3-1. Determine the threshold value of the water inflow unit q of the drilling unit: Because the continuous filling structure is water-proof, when q<0.001L/sm in the pumping test, the pumping interval will be water-tight, and q<0.001L/sm is determined. The interval is a water-filled filling belt; because the intermittent filling structure is weakly permeable, when the pumping test is 0.001<q<0.01L/sm, the pumping interval is weakly permeable, and 0.001<q<0.01L/sm is determined. The layer is a weakly permeable filling belt; because the unfilled structure is rich in water, when the pumping test is q>0.01L/sm, the pumping interval is rich in water, and the interval of q>0.01L/sm is determined to be rich in water. Type filling belt;

3-2. Determining the threshold of the amount of water released in the well: The water richness of the structure of the filling belt is the same as that of the 3-1 step. The threshold of the Q threshold determined by the step 1 and the depth of the buried depth is greater than the average depth of the 300 m, and the threshold of Q is obtained; The location of the coal with a depth of more than 300m is determined, and the water pressure value of the ash is determined to be 4 levels, which are 3MPa, 4MPa, 5MPa, 6MPa respectively, and the water level drop in the pumping and discharging test is assumed to be the maximum depth, ie 300m, 400m, 500m, 600m respectively; determine the threshold of the amount of water inflow from the borehole;

3-3. Determining the threshold of the permeability coefficient K: The water-rich structure of the filling belt is the same as the 3-1 step. When the permeability coefficient is K<10 ^-5 cm/s in the pumping test, the test interval is water-tight, and the K is determined. <10 ^-5 cm/s is a water-filling type filling belt; when the permeability coefficient is 10 ^-5 <K<10 ^-4 cm/s in the pumping test, the test interval is weakly permeable, and it is determined that 10 ^-5 <K<10 ^-4 cm/s is a weakly permeable filling belt; in the pumping test, when the permeability coefficient is K>10 ^-4 cm/s, the test interval is rich in water, and it is determined that K>10 ^-4 cm/s is water-rich. Filling tape

Second, the structure determination method described, the specific steps are as follows:

1. According to the above evaluation index and its threshold value, comprehensively determine the type of filling belt and the thickness of each type. For the water-proof filling belt, it can be directly used as the water-repellent layer; for the weak-permeable filling belt, after the grouting transformation It is used; the water-rich filling belt has the same permeability as the underlying ash, and cannot be used as a water-repellent layer;

2. Draw the contour map of the thickness of the water-proof filling belt, the contour map of the water inrush coefficient of the water-proof filling belt, and the contour map of the water inrush coefficient of the water-blocking filling belt; The contour map is compared and analyzed to determine the safe mining area of the next group of coal.

The present invention will be further described below by means of figures, tables and examples.

Embodiment 1: The structural discrimination index: the drilling unit water inflow amount q, the downhole water discharge amount Q, and the permeability coefficient K are as follows:

1. Obtaining the water inflow unit q index of the drilling unit: The ground drilling hole comprehensively determines the development termination depth of the filling belt according to the core take-up rate, the flushing liquid consumption and the degree of shale development. It is determined that the lithology adoption rate is less than 50%, and the termination depth of the shale development is the development termination depth of the filling zone; thus, the interval of the pumping test is determined to be the interval from the entry of the ash to the depth, and is calculated according to formula (1). The q value of the interval;

2. Acquisition of the Q indicator of the underground water discharge: the water discharge test is carried out on the underground drilling hole, and the water discharge amount of the interval is recorded every 2 m; for the previous underground water discharge test without such a large density record, the recorded water discharge amount Q is performed. The fitting analysis is described by a fitting formula of a certain water drainage hole, such as formula (2), and the water discharge amount obtained from each depth of entering the ash is obtained;

3. Acquisition of permeability coefficient K: The water discharge test is carried out on the underground drilling hole, and the stable water pressure P _{1 of} each interval and the instantaneous water pressure P ₂ when the valve is closed during the water discharge process are recorded respectively, which represents the water discharge test of the interval. The water pressure value in the process, thereby calculating the actual depth value S during the water discharge process, according to formula (3) (4), the permeability coefficient K of the interval can be calculated;

The thresholds of the indicators (q, Q, and K) are determined by the following methods, and the specific steps are as follows:

4. Determine the interval of the water inflow unit q<0.001L/sm is the water-blocking filling belt; 0.001<q<0.01L/sm is the weak permeable filling belt; the layer with q>0.01L/sm is rich Water-type filling belt; according to the permeability coefficient K value, it is determined that K<10 ^-5 cm/s is a water-proof filling belt; 10 ^-5 <K<10 ^-4 cm/s is a weak permeable filling belt; K>10 ^{- 4} cm / s is a water-rich filling belt; and according to the location of the coal in the eastern mining area, the water pressure value of the Austrian ash is determined to be 4 levels, respectively 3MPa, 4MPa, 5MPa, 6MPa, and the pumping and discharging are assumed. The test water level is deeper to the maximum, that is, 300m, 400m, 500m, 600m respectively; the threshold value of the water inflow of the borehole is determined;

As shown in Table 1, Table 2

Table 1 Classification of the type of filling belt in the eastern mining area - q, K threshold

Table 2: Classification of the type of filling belt in the eastern mining area - Q threshold

6. According to the above evaluation index and its threshold value, comprehensively determine the type of filling belt and the thickness of each type (such as Tables 3, 4 and 5). For safety reasons, determine the thickness of the filling belt as the minimum thickness determined by the three indicators.

Table 3 Statistics of water inflow data of the ash drilling unit in Baodian Coal Mine

Hole number	Estimated value of water inflow from drilling unit q(L/(s.m))	Thickness (m)	Filling belt type
				O2-2	0.0079	49.42	Weak aquifer
O2-3	0.0078	54.00	Weak aquifer
				O2-7	0.0022	83.6	Weak aquifer
O2-8	0.006	75.47	Weak aquifer

Table 4 Statistics on the amount of water inflow from the bottom of the Baodian coal mine

drilling	Water-proof filling tape thickness (m)	Weak permeable filling tape thickness (m)
			O2X-1	10.10	81.75
O2X-2	0.23	13.73
			O2X-3	1.63	6.89
O2X-4	7.04	0.89
			O2X-5	7.09	94.08
O2X-6	103.10	-------
			O2X-7	19.74	40.74

O2X-8	3.18	38.62
			O2X-9	87.95	10.59
O2X-10	17	-------
			O2X-11	22.57	9.63
O2X-13	-------	19.18

Table 5: Permeation coefficient values obtained from pumping and discharging tests in Baodian Coal Mine

7. Draw the contour map of the thickness of the water-blocking filling belt of Baodian Coal Mine (Figure 3). And the contour map of the water inrush coefficient (Fig. 4) without considering the water-blocking filling belt, and the contour map of the water inrush coefficient considering the water-blocking filling belt (Fig. 5); and performing the above two contour maps Contrast, analyze, analyze the change of water inrush coefficient of the two maps (Table 6), and determine the safe mining area of the coal below the Baodian coal mine.

Table 6 Baodian Mine Safety Evaluation Area (km ² )

It can be seen from Table 6 and Figure 4 and Figure 5 that the safety zone of the 17 coals is increased by 8.09km ² when considering the filling zone, the safety zone is mainly distributed in the first exploration zone, the increase is 13.55%, and the relative safety zone is increased by 13.66km ² . The increase was 22.88%; the danger zone decreased by 21.81km ² , a decrease of 36.43%. It can be seen that the filling belt is more advantageous for the 17 coal mining, which greatly increases the safety zone and the relative safety zone, and the dangerous zone is greatly reduced.

Claims (1)

1. A discriminating index and determining method for the top of the ash top filling belt structure, characterized in that: the invention comprises a structure discriminating index and a structure determining method;

   I. The structure discriminating index: Firstly, the three filling belt structures of continuous filling, intermittent filling and non-filling are determined. According to the three filling belt structures, the discriminating indexes are determined as follows: drilling unit water inflow q, downhole water discharge Q and Austrian The permeability coefficient of the gray layer segment is K; then the threshold values of each index are determined according to the different water-blocking properties of the three structures;

   The indicators are obtained by the following methods, as follows:

   1. Firstly, a large number of samples of the outcrop of the filling belt are taken to investigate the filling of the shale filled with cracks, and the filling belt is filled according to the degree of filling of the crack, which can be identified as: continuous filling, intermittent filling and no filling. Structure; the types of filling belts corresponding to the three types of filling belt structures are water-blocking type, weakly permeable type and water-rich type;

   2. When the depth of the filling belt is more than 300m, the three indicators of the filling belt structure are determined according to the pumping and discharging experiments, namely: the water inflow amount q of the drilling unit, the water discharge amount Q in the underground and the permeability coefficient K in the Austrian ash layer;

   2-1. Acquisition of the water inflow unit q index of the drilling unit: The ground drilling is based on the core take-up rate, the flushing fluid consumption and the degree of shale development, and comprehensively determine the development termination depth of the filling belt; determine the lithology adoption rate is less than 50%. The depth of the shale development is the depth of development of the filling zone; thus, the interval of the pumping test is determined to be the interval from the entry of the ash to the depth, and the q value of the interval is calculated according to formula (1);

   

   Where, Q is the well flow, m3/s; M is the thickness of the pumping interval, m; sw is the depth of the water level in the well, m; R is the radius of influence, m; rw is the radius of the pumping well, m;

   2-2. Acquisition of Q indicator for underground water discharge: The water discharge test is carried out on the underground drilling hole, and the water discharge amount of the interval is recorded every 2m; for the previous underground water discharge test without such large density record, the recorded water discharge amount Q , the fitting analysis is carried out, and the fitting formula of a certain water drainage hole is used for description, and the formula (2) is obtained from the water discharge amount of each depth entering the Austrian ash;

   Q=63.56ln(x)-483.8 (2)

   Where x is the depth of entering the ash, m; Q enters the water inflow to the depth of the ash, m ³ / s;

   2-3. Acquisition of permeability coefficient K: The water discharge test is carried out on the underground drilling hole, and the stable water pressure P _{1 of} each interval and the instantaneous water pressure P ₂ when the valve is closed during the discharge process are recorded respectively, that is, the interval is represented. The water pressure value during the water discharge test, calculate the actual deepening value S during the water discharge process, and calculate the permeability coefficient K of the interval according to formula (3) (4);

   

   

   Where K is the permeability coefficient, cm/s; other parameters have the same meaning as formula (1);

   3. The method for determining the threshold value of the water inflow unit q index, the downhole water release Q index and the permeability coefficient K index, the specific steps are as follows:

   3-1. Determine the threshold value of the water inflow unit q of the drilling unit: Because the continuous filling structure is water-proof, when q<0.001L/sm in the pumping test, the pumping interval will be water-tight, and q<0.001L/sm is determined. The interval is a water-proof filling belt; due to the intermittent filling structure In the case of weak water permeability, when the pumping test is 0.001<q<0.01L/sm, the pumping interval is weakly permeable, and the interval of 0.001<q<0.01L/sm is determined to be a weakly permeable filling belt; For water-rich, when the pumping test is q>0.01L/sm, the pumping interval is rich in water, and the layer with q>0.01L/sm is determined to be a water-rich filling zone;

   3-2. Determining the threshold of the amount of water released in the well: The water richness of the structure of the filling belt is the same as that of the 3-1 step. The threshold of the Q threshold determined by the step 1 and the depth of the buried depth is greater than the average depth of the 300 m, and the threshold of Q is obtained; The location of the coal with a depth of more than 300m is determined, and the water pressure value of the ash is determined to be 4 levels, which are 3MPa, 4MPa, 5MPa, 6MPa respectively, and the water level drop in the pumping and discharging test is assumed to be the maximum depth, ie 300m, 400m, 500m, 600m respectively; determine the threshold of the amount of water inflow from the borehole;

   3-3. Determining the threshold of the permeability coefficient K: The water-rich structure of the filling belt is the same as the 3-1 step. When the permeability coefficient is K<10 ^-5 cm/s in the pumping test, the test interval is water-tight, and the K is determined. <10 ^-5 cm/s is a water-filling type filling belt; when the permeability coefficient is 10 ^-5 <K<10 ^-4 cm/s in the pumping test, the test interval is weakly permeable, and it is determined that 10 ^-5 <K<10 ^-4 cm/s is a weakly permeable filling belt; in the pumping test, when the permeability coefficient is K>10 ^-4 cm/s, the test interval is rich in water, and it is determined that K>10 ^{- 4} cm/s is water-rich. Filling tape

   Second, the structure determination method described, the specific steps are as follows:

   1. According to the above evaluation index and its threshold value, comprehensively determine the type of filling belt and the thickness of each type. For the water-proof filling belt, it can be directly used as the water-repellent layer; for the weak-permeable filling belt, after the grouting transformation It is used; the water-rich filling belt has the same permeability as the underlying ash, and cannot be used as a water-repellent layer;

   2. Draw the contour map of the thickness of the water-proof filling belt, the contour map of the water inrush coefficient of the water-proof filling belt, and the contour map of the water inrush coefficient of the water-blocking filling belt; The contour map is compared and analyzed to determine the safe mining area of the next group of coal.

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