Effective identification method for water-preserving coal mining area in weathered bedrock aquifer

Abstract

The present application relates to the field of geological mining. Disclosed is an effective identification method for a water-preserving coal mining area in a weathered bedrock aquifer. The method comprises: classifying the types of stratum structures; when a target stratum area belongs to a first type, and the invasion degree of burnt rock in an aquitard is greater than or equal to a first set threshold value, making a determination on the basis of an initial hydraulic gradient of the aquitard, the hydraulic head height of an unconsolidated sand aquifer and the effective thickness of the aquitard; when the target stratum area belongs to a second type, and the invasion degree of burnt rock in a weathered bedrock aquifer is greater than or equal to a second set threshold value, making a determination on the basis of the water retention capacity and water abundance of the burnt rock in the weathered bedrock aquifer; when the target stratum area belongs to a third type, making a determination on the basis of the invasion degree of the burnt rock in the weathered bedrock aquifer and surface water bodies; and when the target stratum area belongs to a fourth type, directly making a determination. The present application realizes the effective identification of a water-preserving coal mining area in a weathered bedrock aquifer.

Description

An effective identification method of weathered bedrock aquifer water-preserved coal mining area TECHNICAL FIELD

[0001] The present application relates to the technical field of geology and mining, in particular to an effective identification method of weathered bedrock aquifer water-preserved coal mining area. BACKGROUND

[0002] At present, the contradiction between coal mining and water resources and ecological environment protection is prominent in some areas, and water-preserved coal mining must be carried out. The main target horizon of traditional water-preserved coal mining is loose sand layer. Since the loose sand layer is located at the top of the stratum and is directly related to the surface ecology, the area affected by coal mining is the water-preserved coal mining area.

[0003] Weathered bedrock is also an important water resource, but since it does not directly outcrop on the surface, further identification work is needed to identify the area with water-preserved coal mining significance. Compared with the identification of traditional water-preserved coal mining area, the identification of weathered bedrock aquifer water-preserved coal mining area has the following problems: (1) compared with loose sand aquifer, weathered bedrock aquifer has variable lithology, and its water retention in the dry season is an important factor for the identification of water-preserved coal mining area, which has not been considered in the past; (2) there may be hydraulic connection between weathered bedrock aquifer and loose sand aquifer, and hydraulic connection is an important indicator for evaluating weathered bedrock water-preserved coal mining area, which has not been considered in the past.

[0004] In addition, the degree of intrusion of burned and altered rock also has an important influence on the identification of weathered bedrock aquifer water-preserved coal mining area. Burned and altered rock is a special type of rock mass formed by the baking or roasting of surrounding rock near the surface of thick coal seam in the geological history period. According to the outcrop observation and drilling data of burned and altered rock area, it is found that the three zones of burned and altered rock are often not complete and irregularly distributed, which may cause certain intrusion to weathered bedrock or water-resisting soil, and further affect the identification and determination of water-preserved coal mining area. SUMMARY

[0005] The purpose of the present application is to provide an effective identification method of weathered bedrock aquifer water-preserved coal mining area, which can effectively identify the weathered bedrock aquifer water-preserved coal mining area, protect water resources and ecological environment while assisting coal mining, and realize green mining of coal resources.

[0006] To achieve the above purpose, the present application provides the following scheme:

[0007] The present application provides an effective identification method of weathered bedrock aquifer water-preserved coal mining area, which specifically comprises:

[0008] Divide the stratum structure type; the stratum structure type includes: a first type, a second type, a third type and a fourth type;

[0009] determining a target stratum region of the mining area to be mined;

[0010] when the target stratum region belongs to the first type, determining the invasion degree of the burned and altered rock in the aquiclude; if the invasion degree of the burned and altered rock in the aquiclude is less than a first set threshold, judging whether the target stratum region is a weathered bedrock aquifer water-preserved mining area according to the initial hydraulic gradient of the aquiclude, the water head height of the loose sand layer aquifer and the actual thickness of the aquiclude; if the invasion degree of the burned and altered rock in the aquiclude is greater than or equal to the first set threshold, first determining the effective thickness of the aquiclude according to the actual thickness of the aquiclude and the invasion degree of the burned and altered rock, and then judging whether the target stratum region is a weathered bedrock aquifer water-preserved mining area based on the initial hydraulic gradient of the aquiclude, the water head height of the loose sand layer aquifer and the effective thickness of the aquiclude;

[0011] when the target stratum region belongs to the second type, determining the invasion degree of the burned and altered rock in the weathered bedrock aquifer; if the invasion degree of the burned and altered rock in the weathered bedrock aquifer is less than a second set threshold, judging whether the target stratum region is a weathered bedrock aquifer water-preserved mining area according to the water holding capacity and water abundance of the weathered bedrock aquifer; if the invasion degree of the burned and altered rock in the weathered bedrock aquifer is greater than or equal to the second set threshold, judging whether the target stratum region is a weathered bedrock aquifer water-preserved mining area according to the water holding capacity and water abundance of the burned and altered rock in the weathered bedrock aquifer;

[0012] when the target stratum region belongs to the third type, determining the invasion degree of the burned and altered rock in the weathered bedrock aquifer; if the invasion degree of the burned and altered rock in the weathered bedrock aquifer is less than or equal to 0, and there is no surface water body, determining that the target stratum region is a non-weathered bedrock aquifer water-preserved mining area; if the invasion degree of the burned and altered rock in the weathered bedrock aquifer is greater than 0, and there is a surface water body, determining that the target stratum region is a weathered bedrock aquifer water-preserved mining area;

[0013] when the target stratum region belongs to the fourth type, determining that the target stratum region is a weathered bedrock aquifer water-preserved mining area.

[0014] According to the specific embodiments provided in the application, the following technical effects are disclosed:

[0015] The application divides the stratum structure of a mining area into four types, and by judging the stratum structure type to which a target stratum region belongs, the weathered bedrock aquifer water-preserved mining area can be further identified. For the first type, since the loose sand aquifer is exposed on the surface, it has good ecological significance and water supply significance, and therefore the weathered bedrock aquifer should be prevented from robbing the water of the loose sand aquifer; for the second type, since the water-resisting soil layer is directly exposed on the surface, it is generally very difficult to be recharged, but since the weathered bedrock aquifer is covered by the water-resisting soil layer, the evaporation of the weathered bedrock aquifer is less, and therefore mining can be carried out; for the third type, since the weathered bedrock aquifer is directly exposed on the surface without overlying stratum, this type generally occurs at the bottom of a channel, and whether water resource supply or ecological environment supply is affected, the main impact occurs in the dry season; for the fourth type, the weathered bedrock aquifer is covered by the loose sand aquifer, and the two aquifers have close hydraulic connection, and therefore in order to protect the loose sand aquifer which has great ecological significance, the weathered bedrock aquifer must be protected. Through the further judgment of the above four types, the weathered bedrock aquifer water-preserved mining area is effectively identified. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0017] In order to make the above-mentioned purposes, features and advantages of the application more obvious and easy to understand, the application will be further described in detail below with reference to the drawings and specific embodiments.

[0018] As shown in FIG. 1, the embodiment provides an effective identification method of a weathered bedrock aquifer water-preserved mining area, which specifically comprises the following steps:

[0019] Step S1: dividing stratum structure types; the stratum structure types include: a first type, a second type, a third type and a fourth type; the first type is that the weathered bedrock aquifer is covered by the water-resisting soil layer, and the water-resisting soil layer is covered by the loose sand aquifer; the second type is that the weathered bedrock aquifer is covered by the water-resisting soil layer, and the water-resisting soil layer is exposed on the surface; the third type is that the weathered bedrock aquifer is directly exposed on the surface; the fourth type is that the weathered bedrock aquifer is covered by the loose sand aquifer.

[0020] Step S2: determining a target stratum region of a to-be-mined area.

[0021] In the embodiment, the drilling columnar chart is used to identify the target stratum region of the to-be-mined area.

[0022] Step S3: When the target stratum region belongs to the first type, the invasion degree of the burned rock in the aquiclude is determined; if the invasion degree of the burned rock in the aquiclude is less than 10%, it is judged whether the target stratum region is a water-preserved coal mining area of the weathered bedrock aquifer according to the initial hydraulic gradient of the aquiclude, the water head height of the loose sand aquifer and the actual thickness of the aquiclude; if the invasion degree of the burned rock in the aquiclude is greater than or equal to 10%, the effective thickness of the aquiclude is determined according to the actual thickness of the aquiclude and the invasion degree of the burned rock, and then it is judged whether the target stratum region is a water-preserved coal mining area of the weathered bedrock aquifer based on the initial hydraulic gradient of the aquiclude, the water head height of the loose sand aquifer and the effective thickness of the aquiclude.

[0023] In the embodiment, if the invasion degree of the burned rock in the aquiclude is greater than or equal to 10%, the following steps are specifically performed:

[0024] The invasion thickness of the burned rock is calculated according to the invasion degree of the burned rock in the aquiclude;

[0025] The difference between the actual thickness of the aquiclude and the invasion thickness of the burned rock is determined as the effective thickness of the aquiclude;

[0026] The ratio of the water head height of the loose sand aquifer to the effective thickness of the aquiclude is calculated to obtain a seepage ratio;

[0027] When the initial hydraulic gradient of the aquiclude is less than or equal to the seepage ratio, the target stratum region is determined as a water-preserved coal mining area of the weathered bedrock aquifer;

[0028] When the initial hydraulic gradient of the aquiclude is greater than the seepage ratio, the target stratum region is determined as a water-preserved coal mining area of the non-weathered bedrock aquifer.

[0029] Step S4: When the target stratum region belongs to the second type, the invasion degree of the burned rock in the weathered bedrock aquifer is determined; if the invasion degree of the burned rock in the weathered bedrock aquifer is less than 5%, it is judged whether the target stratum region is a water-preserved coal mining area of the weathered bedrock aquifer according to the water holding capacity and water abundance of the weathered bedrock aquifer; if the invasion degree of the burned rock in the weathered bedrock aquifer is greater than or equal to 5%, it is judged whether the target stratum region is a water-preserved coal mining area of the weathered bedrock aquifer according to the water holding capacity and water abundance of the burned rock in the weathered bedrock aquifer.

[0030] In the embodiment, the judgment process of the water holding capacity and the water abundance is specifically as follows:

[0031] When the water holding capacity of the burned rock in the weathered bedrock aquifer is greater than or equal to 15%, the target stratum region is determined as a water-preserved coal mining area of the non-weathered bedrock aquifer;

[0032] When the water-holding degree of the burned rock in the weathered bedrock aquifer is less than 15%, it is determined whether the water abundance of the burned rock in the weathered bedrock aquifer is weak or below; if yes, the target stratum region is determined as a non-weathered bedrock aquifer water-preserved coal mining area; if no, the target stratum region is determined as a weathered bedrock aquifer water-preserved coal mining area.

[0033] Step S5: When the target stratum region belongs to the third type, the invasion degree of the burned rock in the weathered bedrock aquifer is determined; if the invasion degree of the burned rock in the weathered bedrock aquifer is less than or equal to 0, and there is no surface water body (in dry season), the target stratum region is determined as a non-weathered bedrock aquifer water-preserved coal mining area; if the invasion degree of the burned rock in the weathered bedrock aquifer is greater than 0, and there is a surface water body (in dry season), the target stratum region is determined as a weathered bedrock aquifer water-preserved coal mining area.

[0034] Step S6: When the target stratum region belongs to the fourth type, the target stratum region is determined as a weathered bedrock aquifer water-preserved coal mining area.

[0035] In addition, the embodiment further provides a coal mining method, which mainly determines the weathered bedrock aquifer water-preserved coal mining area in the to-be-mined region by using the effective identification method of the weathered bedrock aquifer water-preserved coal mining area, and takes water-preserved coal mining measures for the weathered bedrock aquifer water-preserved coal mining area.

[0036] The principles and implementation manners of the present application are described by using specific examples in the present application, and the above examples are only used to help understand the method and core idea of the present application; meanwhile, according to the idea of the present application, the specific implementation manners and application range will be changed by the person skilled in the art. In conclusion, the content of the present specification should not be understood as the limitation of the present application.

Claims

1. An effective method for identifying water-retaining coal mining areas in weathered bedrock aquifers, characterized in that, Effective methods for identifying water-retaining coal mining areas in weathered bedrock aquifers include: Stratigraphic structure types are classified as follows: Type I, Type II, Type III, and Type IV. Type I consists of a weathered bedrock aquifer overlaid with an impermeable soil layer, which in turn is overlaid with a loose sand aquifer. Type II consists of a weathered bedrock aquifer overlaid with an impermeable soil layer, which is exposed at the surface. Type III consists of a weathered bedrock aquifer directly exposed at the surface. Type IV consists of a weathered bedrock aquifer overlaid with a loose sand aquifer. Identify the target stratigraphic region of the mining area; When the target stratum area belongs to the first type, the intrusion degree of the igneous rock in the impermeable soil layer is determined; if the intrusion degree of the igneous rock in the impermeable soil layer is less than the first set threshold, then the target stratum area is judged as a water-retaining coal mining area of ​​weathered bedrock aquifer based on the initial hydraulic gradient of the impermeable soil layer, the water head height of the loose sand aquifer, and the actual thickness of the impermeable soil layer; if the intrusion degree of the igneous rock in the impermeable soil layer is greater than or equal to the first set threshold, then the effective thickness of the impermeable soil layer is first determined based on the actual thickness of the impermeable soil layer and the intrusion degree of the igneous rock, and then the target stratum area is judged as a water-retaining coal mining area of ​​weathered bedrock aquifer based on the initial hydraulic gradient of the impermeable soil layer, the water head height of the loose sand aquifer, and the effective thickness of the impermeable soil layer. When the target stratum area belongs to the second type, the intrusion degree of the igneous rock in the weathered bedrock aquifer is determined; if the intrusion degree of the igneous rock in the weathered bedrock aquifer is less than the second set threshold, the target stratum area is judged as a water-retaining coal mining area based on the water holding capacity and water-bearing capacity of the weathered bedrock aquifer; if the intrusion degree of the igneous rock in the weathered bedrock aquifer is greater than or equal to the second set threshold, the target stratum area is judged as a water-retaining coal mining area based on the water holding capacity and water-bearing capacity of the igneous rock in the weathered bedrock aquifer. When the target stratum area belongs to type III, determine the intrusion degree of the igneous rock in the weathered bedrock aquifer; if the intrusion degree of the igneous rock in the weathered bedrock aquifer is less than or equal to 0 and there is no surface water, then the target stratum area is determined to be a water-retaining coal mining area in the non-weathered bedrock aquifer; if the intrusion degree of the igneous rock in the weathered bedrock aquifer is greater than 0 and there is surface water, then the target stratum area is determined to be a water-retaining coal mining area in the weathered bedrock aquifer. When the target stratum area belongs to the fourth type, the target stratum area is determined to be a water-retaining coal mining area in the weathered bedrock aquifer; If the intrusion degree of the igneous rock in the impermeable soil layer is greater than or equal to the first set threshold, then the effective thickness of the impermeable soil layer is first determined based on the actual thickness of the impermeable soil layer and the intrusion degree of the igneous rock. Then, based on the initial hydraulic gradient of the impermeable soil layer, the hydraulic head height of the loose sand aquifer, and the effective thickness of the impermeable soil layer, it is determined whether the target stratum area is a water-retaining coal mining area in a weathered bedrock aquifer. Specifically, this includes: The intrusion thickness of the igneous rock is calculated based on the degree of intrusion of the igneous rock in the impermeable soil layer. The difference between the actual thickness of the impermeable soil layer and the intrusion thickness of the pyrometallurgical rock is determined as the effective thickness of the impermeable soil layer. The seepage ratio is obtained by calculating the ratio of the water head height of the loose sand aquifer to the effective thickness of the impermeable soil layer. When the initial hydraulic gradient of the impermeable soil layer is less than or equal to the seepage ratio, the target stratum area is determined to be a water-retaining coal mining area in the weathered bedrock aquifer. When the initial hydraulic gradient of the impermeable soil layer is greater than the seepage ratio, the target stratum area is determined to be a water-retaining coal mining area in a non-weathered bedrock aquifer.

2. The effective identification method for water-retaining coal mining areas in weathered bedrock aquifers according to claim 1, characterized in that, Target stratigraphic regions in the mining area are identified using borehole columnar sections.

3. The effective identification method for water-retaining coal mining areas in weathered bedrock aquifers according to claim 1, characterized in that, When the target stratigraphic region belongs to the third type, it is necessary to obtain the surface water body of the target stratigraphic region during the dry season.