Overlying strata separation layer grouting and slurry overflowing plugging material and plugging method

Abstract

The invention relates to the technical field of overlying strata separation layer grouting, in particular to an overlying strata separation layer grouting and slurry overflowing plugging material and a plugging method. The plugging material is a modified flue gas desulfurization gypsum composite material and comprises the following raw materials in percentage by mass: 50-75% of flue gas desulfurization gypsum, 20-40% of fly ash, 0.1-10% of sulphoaluminate cement, 0.1-5% of slaked lime, 0.1-5% of walnut shells, 0.1-5% of sawdust and 0.1-5% of cottonseed hulls. The modified desulfurized gypsum composite material is formed by taking the desulfurized gypsum and the fly ash which are two solid wastes of thermal power generation as base materials and adding a small amount of sulphoaluminate cement, slaked lime, walnut shells, saw dust and cottonseed hulls, the cost is low, the plugging effect is good, the strength can be rapidly formed, obvious expansion occurs, and the rapid plugging effect is achieved; the plugging agent not only can be used for plugging leakage of overlying strata separation layer grouting, but also can be used for drilling plugging, overlying strata separation layer grouting, goaf grouting and other scenes.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of overburden separation grouting, and particularly relates to an overburden separation grouting spouting blocking material and a blocking method. BACKGROUND

[0002] In the overburden strata of the mining field, the strata playing a decisive role in the rock mass movement is the key layer. When there are multiple hard strata in the overburden strata of the mining field, the strata playing a decisive role in the whole rock mass movement is called the main key layer, and the strata playing a decisive role in the local rock mass movement is called the sub-key layer.

[0003] Overburden isolation grouting filling is an effective method for coal mining under buildings (structures), and its principle is to compress the broken rock mass in the goaf and form a compaction zone by filling the overburden separation zone through high-pressure grouting, so as to jointly control the deformation and breakage of the key layer of the overburden strata with the isolation coal pillar between the compaction zone and the working face, thereby reducing the surface subsidence. With the continuous advancement of the coal mining face, the overburden strata move in groups from bottom to top under the control of the key layer structure of the overburden strata. Since the unbroken key layer blocks the downward transmission of the upper load, the lower coal rock strata produce unloading expansion (including rock strata crushing expansion and elastic expansion).

[0004] Due to the untimely overburden isolation grouting filling and insufficient grouting amount, no effective support is formed under the main key layer in time, with the roof of the coal mining face caving, the water-conducting fractured zone develops upward, the key layer breaks, a water-conducting channel is formed, and a spouting accident is easily caused. When the grouting engineering encounters unfavorable geological conditions such as fault fracture zone, collapse column and unfavorable factors such as unsealed abandoned drill hole and unsealed intact drill hole, a spouting accident is extremely likely to occur. Spouting is a common and extremely difficult-to-handle accident in overburden separation grouting, which affects the grouting effect, delays the construction period, pollutes the surface environment and causes huge economic losses. Therefore, timely and effective plugging work is crucial for the overburden separation grouting engineering. However, the overburden separation grouting is carried out under dynamic water conditions, and the groundwater hydrodynamic field tends to be more complex under the joint action of groundwater and grout. Moreover, the grout is composed of water and fine particles of fly ash and coal gangue, and there is no effective binder in the grout. Under the saturated water condition, the grout is in a plastic and flowable state for a long time. When the grouting engineering encounters unfavorable geological conditions and various unfavorable factors, a spouting accident is extremely likely to occur. Since the water outlet channel is connected with the surface and the fissure is large, the spouting is in the form of pipeline flow, and the plugging work is extremely difficult.

[0005] The selection of the overburden separation grouting spouting plugging material is a crucial work, which determines the overburden separation grouting spouting plugging effect. At the same time, the plugging process also has a relatively obvious influence on the overburden separation grouting spouting plugging effect.

[0006] Therefore, the present application is proposed. SUMMARY

[0007] In view of the poor adhesion of the existing overburden separation grouting and spouting plugging material, the easy flow of the slurry, and the fact that the plugging process cannot effectively deal with the pipe flow and spouting, the present application provides an overburden separation grouting and spouting plugging material and a plugging method to improve the plugging effect and reduce the loss caused by the spouting accident.

[0008] The present application provides an overburden separation grouting and spouting plugging material, which is a modified desulfurization gypsum composite material, and the modified desulfurization gypsum composite material comprises the following raw materials: 50-75% of desulfurization gypsum by mass fraction, 20-40% of fly ash by mass fraction, 0.1-10% of sulphoaluminate cement by mass fraction, 0.1-5% of slaked lime by mass fraction, 0.1-5% of walnut shell by mass fraction, 0.1-5% of sawdust by mass fraction, and 0.1-5% of cotton seed hull by mass fraction.

[0009] Further, the modified desulfurization gypsum composite material comprises the following raw materials: 60.75% of desulfurization gypsum by mass fraction, 30% of fly ash by mass fraction, 5% of sulphoaluminate cement by mass fraction, 0.25% of slaked lime by mass fraction, 1% of walnut shell by mass fraction, 2% of sawdust by mass fraction, and 1% of cotton seed hull by mass fraction.

[0010] Further, when the modified desulfurization gypsum composite material is used, water needs to be added to configure a slurry, and the mass ratio of water to the modified desulfurization gypsum composite material (water-cement ratio) in the slurry is 0.4-1, and the slurry concentration is 50.0%-71.4%. More preferably, the water-cement ratio is 0.5, and the slurry concentration is 66.7%.

[0011] Further, the desulfurization gypsum is composed of calcium sulfate dihydrate (CaSO4·2H2O), the content of which is ≥85% (mass fraction), the attached water content is ≤15% (mass fraction), the chloride ion (Cl - ) content is ≤600 mg / kg, the water-soluble magnesium oxide (MgO) content is ≤0.10% (mass fraction), the water-soluble sodium oxide (Na2O) content is ≤0.06% (mass fraction), and the pH value is 5.0-9.0; the density of the desulfurization gypsum is 2000-2500 kg / m 3 .

[0012] Further, the fly ash contains three oxides of silicon dioxide (Si02), aluminum oxide (Al203), and iron oxide (Fe203), and the sum of the contents of the three oxides is ≥ 50% (mass percentage), the content of free calcium oxide (f-CaO) is ≤ 4.0% (mass percentage), the content of sulfur trioxide (SO3) is ≤ 3% (mass percentage), the water content is ≤ 1.0% (mass percentage), and the loss on ignition (Loss) is ≤ 10% (mass percentage); the fineness of the fly ash is 325 mesh (0.045 mm), and the mass of the residue remaining on the 325 mesh square hole screen is less than 45% of the total mass. The density of the fly ash is 2600 kg / m 3 .

[0013] Further, the content of calcium oxide (CaO) in the Portland-sulphate cement (PSA 42.5) is ≥ 50% (mass percentage), the content of aluminum oxide (Al203) is ≤ 2.0% (mass percentage), the specific surface area is 350 m 2 / kg, the initial setting time is ≥ 25 minutes, the final setting time is ≤ 180 minutes, the compressive strength after 1 day is ≥ 30.0 MPa, the flexural strength after 1 day is ≥ 6.0 MPa, the compressive strength after 3 days is ≥ 42.5 MPa, and the flexural strength after 3 days is ≥ 6.5 MPa. The density of the Portland-sulphate cement is 3100-32500 kg / m 3 .

[0014] Further, the content of calcium hydroxide (Ca(OH)2) in the slaked lime is ≥ 85% (mass percentage), the dry loss is ≤ 1.0% (mass percentage), and the mass of the residue remaining on the 200 mesh (0.075 mm) square hole screen is ≤ 12.0% (mass percentage). The density of the slaked lime is 2240 kg / m 3 .

[0015] Further, the walnut shell is in a granular form, the mass of the residue remaining on the 10 mesh (2.00 mm) square hole screen is ≥ 50% (mass percentage), and the water content is ≤ 8% (mass percentage); the bulk density of the walnut shell is 800-900 kg / m 3 , and the true density is 1250-1280 kg / m 3 ; The sawdust is in a fibrous form, the mass of the residue remaining on the 10 mesh (2.00 mm) square hole screen is ≤ 15% (mass percentage), the water content is ≤ 15% (mass percentage), and the sand content is ≤ 15% (mass percentage); the bulk density of the sawdust is 150-300 kg / m 3 , and the true density is 600-700 kg / m 3 ; The cotton seed hulls are in granular form, and the mass of the residue after passing through a 5-mesh (4.00 mm) square hole sieve is greater than or equal to 70% (mass percentage), and the water content is less than or equal to 10% (mass percentage); the bulk density of the cotton seed hulls is 600-800 kg / m 3 , and the true density is 1200-1300 kg / m 3 .

[0016] The present application provides a kind of overburden separation grouting grouting plugging method, using the above-mentioned plugging material to carry out plugging, including the following steps: S1. a temporary grouting station is established at the grouting hole, the temporary grouting station includes primary mixing pool and secondary mixing, the primary mixing pool is mixed and stirred uniformly with desulfurized gypsum, fly ash, water, the secondary mixing pool is connected in the primary mixing pool and adds sulphoaluminate cement, quicklime and walnut shell, sawdust, cotton seed hull, and is stirred uniformly, grouting pipeline is connected with secondary mixing pool, grouting hole and grouting pump using grouting pipeline; S2. observe grouting hole grouting point, when grouting amount is obviously smaller, grout is obviously clear and stable time is more than 24 hours, carry out grouting amount measurement test and grouting trace test: fly ash grout is used as carrier, sawdust is used as tracer, through temporary grouting station, grouting hole is injected, grouting flow is observed and recorded at grouting point and grout sample is taken;When grouting amount is larger, grout is mixed or sawdust is found to return to surface, stop grouting;Clear water is injected to push grout in hole, when grouting condition at grouting point returns to before test, stop grouting observation and record, and calculate longest time and maximum grouting amount of plugging; S3. according to the test results of step S2, determine the plugging parameters, after the completion of plugging material stirring, start grouting, determine the flow of this plugging grouting according to the maximum grouting amount of plugging, monitor the orifice pressure and grouting condition;When orifice pressure is greater than or equal to the maximum orifice pressure before grouting hole grouting, grouting amount is larger or grout is mixed or reaches longest time, stop grouting;Inject clear water to cut grout, close grouting hole orifice valve;Observe orifice pressure change within 24 hours, determine the opportunity of secondary plugging according to the reason of stopping; S4. if grouting amount is larger, grout is mixed and orifice pressure is not zero within 24 hours after previous plugging operation, carry out 2 times of plugging operation, after 3 times of plugging operation, if grouting amount is not larger or grout is not mixed, it is indicated that grouting plugging is successful.

[0017] Further, the water-cement ratio of the grout used in the grouting trace experiment in step S2 is 1:1, and the mass percentage of water, fly ash and sawdust is 50.00%:47.50%:2.50%.

[0018] Further, the longest time T of plugging in step S2 is T i -T0, wherein T iT is the end time of grouting test, unit is h; T0 is the start time of grouting test, unit is h; The maximum grouting amount of plugging V = V0-V1-V2-…-V n , wherein V0 is the total grouting amount of grouting test, unit is m 3 ; V1 is the grouting amount of the first grouting point, unit is m 3 ; V2 is the grouting amount of the second grouting point, unit is m 3 ; …; V n is the grouting amount of the nth grouting point, unit is m 3 ; V1= (Q0+Q1)÷2×t1+ (Q1+Q2)÷2×t2+…+ (Q k-1 +Q k )÷2×t k V2=(Q0+Q1)÷2×t1+ (Q1+Q2)÷2×t2+…+ (Q k-1 +Q k )÷2×t k … Vn=(Q0+Q1)÷2×t1+ (Q1+Q2)÷2×t2+…+ (Q k-1 +Q k )÷2×t k Q0 is the flow observation value of grouting point at the start of grouting test, unit is m 3 / h; Q1 is the first flow observation value of grouting point after the start of grouting test, unit is m 3 / h; Q2 is the second flow observation value of grouting point after the start of grouting test, unit is m 3 / h; … Q k-1 is the k-1th flow observation value of grouting point after the start of grouting test, unit is m 3 / h; Q k is the kth flow observation value of grouting point after the start of grouting test, unit is m 3 / h; t1 is the time interval between the first flow observation of grouting point after the start of grouting test and the start of grouting test, unit is h; t2 is the time interval between the second flow observation of grouting point after the start of grouting test and the first flow observation, unit is h; generally, the value is 0.5, that is, the time interval between two observations is 30 minutes; … t kThe time interval between the k-th and (k-1)-th observations of the flow rate at the grouting point after the grouting test is expressed in hours.

[0019] Furthermore, the grouting hole adopts a three-section well structure, and the formula for calculating the volume of grout removal water in step S3 is as follows: V 水 =π×(d1÷1000÷2) 2 ×h1+π×(d2÷1000÷2) 2 ×h² + π × (d³ ÷ 1000 ÷ 2) 2 ×h3; Where V 水 The required amount of cleaning water for removing slurry is expressed in cubic meters (m³). 3 d1 is the inner diameter of the first grouting hole casing, in mm; d2 is the inner diameter of the second grouting hole casing, in mm; d3 is the inner diameter of the third grouting hole casing, in mm; h1 is the length of the first grouting hole casing, in m; h2 is the length of the second grouting hole casing, in m; h3 is the length of the third grouting hole casing, in m. Formula for calculating the shortest time required for pulp removal: T 剔 = V 水 ÷Q 泵 ; Where T 剔 Q represents the shortest time required for pulp removal, expressed in hours (h). 泵 This refers to the displacement of the grouting pump used during grout removal, expressed in meters (m). 3 / h.

[0020] In summary, compared with the prior art, the present invention has the following advantages: The technical solution of this invention is based on waste utilization. It uses desulfurized gypsum and fly ash, two solid wastes from thermal power generation, as the matrix material. A small amount of sulfoaluminate cement, quicklime, and inert sealing materials such as walnut shells, sawdust, and cottonseed hulls are added to form a modified desulfurized gypsum composite material. The modified desulfurized gypsum composite material has the characteristics of low cost and good sealing effect. It can quickly form strength and undergo significant expansion to achieve a fast sealing effect. It can be used not only for grouting and sealing leaks caused by overburden separation, but also for drilling sealing, overburden separation grouting, and goaf grouting. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 Figure 1 is a schematic view of a plugging device according to an embodiment of the application, wherein the arrows in the figure indicate the direction of slurry flow.

[0023] Reference signs: 1-desulfurized gypsum material bin; 2-fly ash material bin; 3-feeding pool; 4-first-stage stirring pool; 5-second-stage stirring pool; 6-grouting pump; 7-grouting pipeline; 8-valve; 9-pressure gauge; 10-wellhead device; 11-flange plate; 12-first-stage casing; 13-first-stage cementing cement; 14-first-stage borehole wall; 15-second-stage casing; 16-second-stage cementing cement; 17-second-stage borehole wall; 18-third-stage casing; 19-third-stage cementing cement; 20-third-stage borehole wall; 21-fourth-stage loose deposit; 22-upper rock stratum of key stratum of overburden strata of coal seam; 23-key stratum of overburden strata of coal seam; 24-lower weak rock stratum of key stratum of overburden strata of coal seam; 25-separation space; 26-fracture and fracture zone; 27-unsealed borehole or poorly sealed borehole; 28-grouting point. DETAILED DESCRIPTION

[0024] The technical solutions of the present application will be described below in connection with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0025] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they may refer to a fixed connection, a detachable connection, or an integral connection; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium; and they may refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] Example A grouting and sealing material for overburden delamination is disclosed. The sealing material is a modified desulfurized gypsum composite material, which comprises the following raw materials: desulfurized gypsum, fly ash, sulfoaluminate cement, quicklime, and inert sealing materials: walnut shells, sawdust, and cottonseed hulls. The mass percentages of the desulfurized gypsum are 60.75%, fly ash is 30%, sulfoaluminate cement is 5%, quicklime is 0.25%, walnut shells are 1%, sawdust is 2%, and cottonseed hulls are 1%.

[0028] When using the above-mentioned modified desulfurized gypsum composite material, water needs to be added to prepare a slurry. The mass ratio of water to the modified desulfurized gypsum composite material in the slurry is 0.5, and the slurry concentration is 66.7%. The slurry preparation method is as follows: First, mix and stir the desulfurized gypsum, fly ash, and water evenly. Then, add sulfoaluminate cement, quicklime, walnut shells, sawdust, and cottonseed hulls, and stir evenly.

[0029] The initial setting time of the modified desulfurized gypsum composite material is 2 hours, and the compressive strength and flexural strength can reach 12.4 MPa and 3.0 MPa after 24 hours, respectively.

[0030] The specific steps of the method for sealing grout leakage in overburden delamination using the above-mentioned sealing materials are as follows: S1. Establish a temporary grouting station A temporary grouting station is established at the grouting hole. This temporary grouting station consists of a material silo, a feeding pool, a mixing pool, a grouting pump, and grouting pipelines, etc. Figure 1 As shown: There are two material silos: Desulfurized gypsum silo 1 and fly ash silo 2, which store desulfurized gypsum and fly ash respectively, each with a volume of 50m³. 3The feeding pool 3 is used for weighing and feeding the materials (desulfurization gypsum, fly ash and water), and has a volume of 10 m 3 The stirring pool has two parts, i.e. the first-stage stirring pool 4 and the second-stage stirring pool 5. The first-stage stirring pool 4 is mainly used for mixing and stirring the desulfurization gypsum, fly ash and water uniformly. The second-stage stirring pool 5 is used for receiving the stirred materials in the first-stage stirring pool 4 and adding the sulphoaluminate cement, slaked lime and walnut shell, sawdust and cotton seed shell, and stirring them uniformly. The stirring time is 5-30 minutes, and the optimum stirring time is 10 minutes. The volumes of the first-stage stirring pool 4 and the second-stage stirring pool 5 are 20 m 3 The grouting pump 6 is a F500 type mud pump, and has a rated power of 373 kw, a rated stroke frequency of 165 n -1 , a stroke length of 190.5 mm, a wheel rotation ratio of 4.24:1, an inlet pipe diameter of 203 mm, an outlet pipe diameter of 103 mm, a cylinder diameter of φ100 mm-φ170 mm, a rated pressure of 9.4-27.2 MPa, and a displacement of 12.34-35.67 L / s (44.42-132.01 m 3 / h). The grouting pipeline 7 connects the grouting pump 6 with the second-stage stirring pool 5 and the grouting hole.

[0031] The wellhead device 10, three-opening casing and corresponding cementing cement are arranged at the grouting hole. The three-opening casing includes a first opening casing 12, a second opening casing 15 and a third opening casing 18. The first opening casing 12 is located at the shallowest layer in the ground, and the outer wall of the first opening casing 12 is filled with the first opening cementing cement 13 between the first opening casing 12 and the first opening borehole wall 14. The first opening casing 12 mainly penetrates the fourth system loose deposit 21, and the lower end of the first opening casing 12 extends to the shallow part of the upper rock layer 22 of the coal seam overburden key layer. The second opening casing 15 is nested inside the first opening casing 12, and the length of the second opening casing 15 is greater than that of the first opening casing 12. The outer wall of the second opening casing 15 is filled with the second opening cementing cement 16 between the second opening casing 15 and the second opening borehole wall 17. The casing penetrates the upper rock layer 22 of the coal seam overburden key layer, and the lower end of the casing extends to the upper part of the coal seam overburden key layer 23 (such as sandstone layer). The third opening casing 18 is nested inside the second opening casing 15, and is the deepest casing. The outer wall of the third opening casing 18 is filled with the third opening cementing cement 19 between the third opening casing 18 and the third opening borehole wall 20. The casing penetrates the coal seam overburden key layer 23, and the lower end of the casing extends to the separation space 25.

[0032] The outlet section of the grouting pipeline 7 is connected with the wellhead device 10 through the valve 8, and the wellhead device 10 is communicated with the first opening casing 12. The pressure gauge 9 is arranged on the wellhead device 10, and is used for monitoring the grouting pressure.

[0033] The slurry is injected into the overburden separation space 25, the fracture and broken zone 26 and the unsealed or poorly sealed borehole 27 through the third opening casing, so as to realize the grouting sealing.

[0034] In addition, the temporary grouting station is also equipped with two 12-ton water tank trucks, which are used for transporting and storing the grouting water. The grouting water is ordinary drinking water (tap water or well water).

[0035] S2. Conducting the amount of gushing measurement test and gushing tracing test S21. Test preparation and judgment of starting conditions: observe the gushing situation at the gushing point. When the amount of gushing at the gushing point is obviously reduced, the slurry is obviously clear, and the duration of this stable state is more than 24 hours, the amount of gushing measurement test and gushing tracing test can be started; S22. Test slurry preparation and injection: using fly ash slurry as carrier and sawdust as tracer, in order to quickly determine the amount of gushing, the maximum amount of grouting and the time of grouting slurry gushing to the ground surface, a high water-cement ratio of 1:1 is used, i.e. the mass percentage of water, fly ash and sawdust is 50.00%:47.50%:2.50%. The slurry is directly injected into the gushing grouting hole through the orifice at the temporary grouting station; S23. Test observation and recording: arrange special personnel to observe and record the gushing flow at the gushing point in real time, and collect the slurry. The date and time are marked on the mineral water bottle cap. The general observation and recording time interval is 30 minutes. It is recommended to use whole half an hour and whole hour as the recording basis. The grouting starts at half an hour or whole hour. The observation and recording should also be started at the beginning. When the gushing slurry is obviously mixed (the concentration of gushing slurry is greater than or equal to the concentration of grouting slurry, i.e. the concentration of gushing slurry is greater than or equal to 50%), the amount of gushing is obviously increased, or sawdust is found to return to the ground surface, the observation and recording should be encrypted; The time difference between the time when the amount of gushing is obviously increased, the slurry is obviously mixed, and the sawdust is found to return to the ground surface and the starting time of grouting is the longest time of plugging and grouting; When the gushing slurry is obviously mixed, the amount of gushing is obviously increased, or the sawdust returns to the ground surface, the grouting should be stopped immediately. Clean water is injected into the grouting hole to push out all the test slurry remaining in the grouting hole; The gushing situation at the gushing point is continuously observed and recorded. When the amount of gushing at the gushing point is obviously reduced and the slurry is obviously clear, i.e. the amount of gushing at the gushing point basically returns to the amount of gushing before the plugging and grouting test, the observation and recording of gushing should be stopped; S24. Test end, calculate the longest plugging time and the maximum amount of grouting: (1) Longest plugging time T=T i - T0 T is the longest plugging time (h); T i is the end time of grouting test (Beijing time such as 13:30, which needs to be converted to 13.50, unit hour h); T0 is the start time of grouting test (Beijing time such as 9:00, converted to 9.00, unit hour h).

[0036] Time conversion formula: T n = h n + m n ÷ 60 T n is the result of the time of the n observation recorded in the pure data format, unit h; h n is the hour number of the time of the n observation recorded in Beijing time, unit h; m n is the minute number of the time of the n observation recorded in Beijing time, unit min; (2) Maximum grouting amount for plugging V=V0-V1- V2-…-V n V is the maximum grouting amount for plugging, V0 is the total grouting amount of the grouting test (m 3 ), V1 is the grouting amount of the first grouting point (m 3 ), V2 is the grouting amount of the second grouting point (m 3 ), …, V n is the grouting amount of the n grouting point (m 3 ), V1= (Q0+Q1)÷2×t1+ (Q1+Q2)÷2×t2+…+ (Q k-1 +Q k )÷2×t k V2=(Q0+Q1)÷2×t1+ (Q1+Q2)÷2×t2+…+ (Q k-1 +Q k )÷2×t k … V n =(Q0+Q1)÷2×t1+ (Q1+Q2)÷2×t2+…+ (Q k-1 +Q k )÷2×t k Q0 is the flow observation value of the grouting point at the beginning of the grouting test, unit m 3 / h; Q1 is the first flow observation value of the grouting point after the beginning of the grouting test, unit m 3 / h; Q2 is the second flow observation value of the grouting point after the beginning of the grouting test, unit m 3 / h; … Q k-1 is the k-1 flow observation value of the grouting point after the beginning of the grouting test, unit m 3 / h; Q k is the k flow observation value of the grouting point after the beginning of the grouting test, unit m 3 / h; t1 is the time interval between the first observation of the flow rate at the point of mud outflow after the grouting test and the start of the grouting test, in hours; t2 is the time interval between the second observation of the flow rate at the point of mud outflow after the grouting test and the first observation, in hours, generally taking a value of 0.5, i.e. the time interval between the two observations is 30 minutes; … t k t is the time interval between the kth observation of the flow rate at the point of mud outflow after the grouting test and the (k-1)th observation, in hours.

[0037] S3. Implementing the mud outflow plugging operation of the grouting hole S31. Determining the plugging parameters: based on the results obtained from the mud outflow measurement and the mud outflow tracing test in step S2, the longest time and the maximum grouting amount for mud outflow plugging under a certain grouting flow rate are determined.

[0038] According to the initial setting time of the plugging material being 2 hours, the longest grouting plugging time cannot exceed 2 hours; according to the maximum grouting amount and the grouting time of 2 hours, the maximum grouting flow rate for grouting plugging is determined. In this case, a F500 type mud pump with a displacement of 44.42-132.01 m 3 / h is used, which can meet the requirements of the grouting flow rate of 50-100 m 3 / h for plugging grouting operation. S32. Plugging grouting operation: after the plugging material is mixed, grouting is started, the flow rate of this plugging grouting is determined according to the maximum grouting flow rate determined based on the previous test results, and at the same time, a person is arranged to observe and record the mud outflow flow rate and the changes of the grouting at the mud outflow point at regular intervals, collect grouting samples, and mark the date and time on the bottle cap of the grouting sample, generally observing once every half an hour, and it is recommended to take whole half hours and whole hours as the recording basis. When the mud outflow amount increases and the grouting is obviously mixed (the concentration of the mud outflow grouting is greater than or equal to the concentration of the grouting body, i.e. the concentration of the mud outflow grouting is greater than or equal to 50%), the measurement needs to be increased. When plugging grouting, the changes of the orifice pressure of the grouting hole need to be observed in real time, and when the orifice pressure is greater than or equal to the maximum orifice pressure before the grouting hole outflows mud, the grouting needs to be stopped immediately; when the mud outflow flow rate at the point of mud outflow obviously increases or the grouting is obviously turbid, the grouting needs to be stopped immediately; when the grouting time reaches 2 hours, the grouting needs to be stopped immediately.

[0039] After the plugging grouting is stopped, the grouting in the hole needs to be pushed out into the separation space to prevent the plugging grouting from being solidified and blocking the grouting hole. The grouting is pushed out of the grouting hole by using clean water, and the shortest time required for the grouting is calculated according to the amount of clean water required for the grouting and the displacement of the grouting pump used during the grouting. Generally, to ensure that the grouting is completely removed, the grouting time needs to be longer than the shortest time required for the grouting.

[0040] After the grouting is completed, the orifice valve of the grouting hole is closed and the pressure is blocked.

[0041] The volume calculation formula of the water for cleaning the slurry: V 水 = π × (d1 ÷ 1000 ÷ 2) × h1 + π × (d2 ÷ 1000 ÷ 2) × h2 + π × (d3 ÷ 1000 ÷ 2) × h3 2 2 2 V 水 is the required amount of water for cleaning the slurry, and the unit is m 3 ; d1 is the inner diameter of the first open casing of the grouting hole, and the unit is mm; d2 is the inner diameter of the second open casing of the grouting hole, and the unit is mm; d3 is the inner diameter of the third open casing of the grouting hole, and the unit is mm; h1 is the length of the first open casing of the grouting hole, and the unit is m; h2 is the length of the second open casing of the grouting hole, and the unit is m; h3 is the length of the third open casing of the grouting hole, and the unit is m; The shortest time calculation formula required for grouting: T 剔 = V 水 ÷ Q 泵 T 剔 is the shortest time required for grouting, and the unit is h; Q 泵 is the displacement of the grouting pump during grouting, and the unit is m 3 / h; After the plugging grouting is completed, the change of the orifice pressure of the grouting hole is observed in real time, and whether the orifice pressure can be zeroed within 24 hours and how long it takes to be zeroed are observed. If the plugging grouting is stopped due to the fact that the amount of grouting is obviously increased and the grouting point is obviously turbid, then the plugging grouting operation can be started again after the amount of grouting is reduced and becomes clear. If the plugging grouting is stopped due to the fact that the hole pressure is too large and reaches the longest time (2 h) of plugging, then the second plugging grouting can be started after 24 hours.

[0042] S4. Implementing the grouting hole grouting plugging and reinforcing operation During the previous grouting plugging operation, if the amount of grouting is not obviously increased and the grouting point is not obviously turbid, and the orifice pressure of the grouting hole is not zeroed within 24 hours after the plugging is stopped, then it is indicated that the grouting plugging operation has effectively achieved the plugging effect. In order to consolidate the plugging results, 2 times of plugging operation are required. After the 3 times of plugging operation are completed, if the amount of grouting at the grouting point is not obviously increased and changed, then it is indicated that the grouting plugging is successful.

[0043] S5. Resuming the overburden separation layer grouting operation​​​ After the success of the grouting hole grouting plugging, the original grouting system is used to continue the overburden separation grouting operation according to the normal grouting process and parameters, to ensure the smooth progress of the whole overburden reinforcement project.

[0044] The present application is based on waste utilization, using desulfurization gypsum and fly ash, two solid wastes of thermal power generation, as base materials, adding a small amount of sulphoaluminate cement, quicklime and inert plugging materials such as walnut shells, sawdust and cottonseed hulls, to form modified desulfurization gypsum composite material. The modified desulfurization gypsum composite material has the characteristics of low cost and good plugging effect, can quickly form strength and expand significantly to achieve the effect of fast plugging. It can be used not only for overburden separation grouting plugging, but also for drilling plugging, overburden separation grouting, goaf grouting and other scenes.

[0045] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A material for covering rock separation grouting and spouting plugging, characterized in that, The plugging material is a modified desulfurization gypsum composite material, which comprises the following raw materials: 50-75% of desulfurization gypsum, 20-40% of fly ash, 0.1-10% of sulphoaluminate cement, 0.1-5% of lime, 0.1-5% of walnut shell, 0.1-5% of sawdust, and 0.1-5% of cotton seed hull.

2. The occlusive material of claim 1, wherein, The modified desulfurization gypsum composite material comprises the following raw materials: 60.75% of desulfurization gypsum, 30% of fly ash, 5% of sulphoaluminate cement, 0.25% of lime, 1% of walnut shell, 2% of sawdust, and 1% of cotton seed hull.

3. The occlusive material of claim 1, wherein, When the modified desulfurization gypsum composite material is used, water is added to configure a slurry, and the mass ratio of water to the modified desulfurization gypsum composite material in the slurry is 0.4-1, and the slurry concentration is 50.0%-71.4%.

4. The occlusive material of claim 1, wherein, The desulfurization gypsum has the following components: calcium sulfate dihydrate, content ≥ 85%, attached water content ≤ 15%, chloride ion content ≤ 600 mg / kg, water-soluble magnesium oxide content ≤ 0.10%, water-soluble sodium oxide content ≤ 0.06%, and pH value 5.0-9.0; and the density of the desulfurization gypsum is 2000-2500 kg / m 3 .

5. The occlusive material of claim 1, wherein, The fly ash contains three oxides of silicon dioxide, di-aluminum trioxide and di-iron trioxide, and the total content of the three oxides is greater than or equal to 50%, the free calcium oxide content is less than or equal to 4.0%, the sulfur trioxide content is less than or equal to 3%, the water content is less than or equal to 1.0%, the loss on ignition is less than or equal to 10%, and the fineness of the fly ash is 325 mesh, and the mass of the residue on the screen after passing through the 325 mesh square hole screen is less than 45% of the total mass.

6. The occlusive material of claim 1, wherein, The sulphoaluminate cement has an oxidation content of ≥50%, an alumina content of ≤2.0%, a specific surface area of 350 m 2 / kg, an initial setting time of ≥25 minutes, and a final setting time of ≤180 minutes; the slaked lime has a calcium hydroxide content of ≥85%, a dry loss of ≤1.0%, and a mass of residue after passing through a 200-mesh square-hole sieve of ≤12.0%.

7. The occlusive material of claim 1, wherein, The walnut shell is granular, and the mass of the residue on the screen after passing through a 10 mesh square hole screen is greater than or equal to 50%, and the water content is less than or equal to 8%; The sawdust is fibrous, and the mass of the residue on the screen after passing through a 10 mesh square hole screen is less than or equal to 15%, the water content is less than or equal to 15%, and the sand content is less than or equal to 15%; The cotton seed hull is granular, and the mass of the residue on the screen after passing through a 5 mesh square hole screen is greater than or equal to 70%, and the water content is less than or equal to 10%.

8. A method for caving-in prevention by grouting in the separation layer of overburden rock, characterized in that, The plugging material is used for plugging, and the method comprises the following steps: S1. A temporary grouting station is established at the grouting hole, and the temporary grouting station comprises a primary mixing pool and a secondary mixing pool, the desulfurization gypsum, the fly ash and water are mixed and stirred uniformly in the primary mixing pool, the secondary mixing pool receives the stirred material in the primary mixing pool and adds the sulphoaluminate cement, the lime and the walnut shell, the sawdust and the cotton seed hull, and the secondary mixing pool is stirred uniformly, and a grouting pump is connected to the secondary mixing pool and the grouting hole through a grouting pipeline; S2. The grouting point is observed, when the grouting amount is obviously reduced, the slurry is obviously clear, and the stable time is more than 24 hours, the grouting amount measurement test and the grouting tracing test are carried out: the fly ash slurry is used as a carrier, the sawdust is used as a tracer, the temporary grouting station is used to inject the grouting hole, the grouting flow is observed and recorded at the grouting point, and the slurry sample is collected; when the grouting amount is large, the slurry is mixed, or the sawdust is found to return to the ground surface, the grouting is stopped; clean water is injected to push the slurry in the hole, and when the grouting condition at the grouting point returns to the condition before the test, the grouting observation and recording are stopped, and the longest plugging time and the maximum grouting amount are calculated. S3. According to the test results of step S2, determine the plugging parameters. After the plugging material is mixed, start grouting. According to the maximum grouting amount, determine the flow rate of the current plugging grouting. Monitor the orifice pressure and grouting situation. When the orifice pressure is greater than or equal to the maximum orifice pressure before grouting, the grouting amount increases, the grout becomes mixed, or the plugging time reaches the maximum, stop grouting. Inject clean water to remove grout, and close the orifice valve. Observe the orifice pressure change within 24 hours, and determine the timing of the second plugging according to the stopping reason; S4. If the previous plugging operation does not have the conditions of large grouting amount, mixed grout, and orifice pressure not returning to zero within 24 hours, perform 2 more plugging operations. If there is no condition of large grouting amount or mixed grout after 3 plugging operations, it means that the grouting plugging is successful.

9. The method of claim 8, wherein, The longest time T=T i -T0, wherein T i is the end time of the grouting test, in h; T0 is the start time of the grouting test, in h; The maximum grouting amount for plugging leakage V = V0-V1-V2-…-V n , wherein V0 is the total grouting amount of the grouting test, in units of m 3 ; V1 is the grouting amount of the first grouting point, in units of m 3 ; V2 is the grouting amount of the second grouting point, in units of m 3 ; …; V n is the grouting amount of the nth grouting point, in units of m 3 ; V1= (Q0+Q1)÷2×t1+ (Q1+Q2)÷2×t2+…+ (Q k-1 +Q k )÷2×t k V2 = (Q0 + Q1) ÷ 2 x t1 + (Q1 + Q2) ÷ 2 x t2 +... + (Qn-1 + Qn) ÷ 2 x tn-1 + (Qn + Q0) ÷ 2 x tn k-1 + Q k ) ÷ 2 x t k … Vn = (Q0 + Q1) ÷ 2 x t1 + (Q1 + Q2) ÷ 2 x t2 +... + (Qn-1 + Qn) ÷ 2 x tn k-1 +Q k )÷2 x t k Q0 is the observed value of the flow rate at the point of the grouting test at the beginning, in m 3 / h; Q1 is the first observed value of the flow rate at the point of the mud burst after the beginning of the grouting test, in m 3 / h; Q2 is the second observed value of the flow rate at the point of the grouting test after the start, in m 3 / h; … Q k-1 Qk-1is the k-1th observation value of the flow rate of the point of the mud outburst after the beginning of the grouting test, in units of m 3 / h; Q k Qkis the kth observation of the flow rate of the point of the grouting test after the start of the grouting test, in m 3 / h; t1 is the time interval between the first observation of the grouting point flow after the grouting test and the start of the grouting test, in hours; t2 is the time interval between the second observation of the grouting point flow after the grouting test and the first observation, in hours; … t k is the time interval between the kth and (k-1)th observations of the flow rate at the point of the blowout after the grouting test, in hours.

10. The method of plugging of claim 8, wherein, The grouting hole adopts a three-opening well type structure. The volume calculation formula of the clean water for removing grout in step S3 is: V 水 = π x (d1 ÷ 1000 ÷ 2) 2 x h1 + π x (d2 ÷ 1000 ÷ 2) 2 x h2 + π x (d3 ÷ 1000 ÷ 2) 2 x h3; V 水 The amount of water required for the slurry is m 3 ; d1 is the inner diameter of the first casing pipe of the grouting hole, in mm; d2 is the inner diameter of the second casing pipe of the grouting hole, in mm; d3 is the inner diameter of the third casing pipe of the grouting hole, in mm; h1 is the length of the first casing pipe of the grouting hole, in m; h2 is the length of the second casing pipe of the grouting hole, in m; h3 is the length of the third casing pipe of the grouting hole, in m; The shortest time required for the slip calculation formula: T 剔 = V 水 ÷Q 泵 ; where T 剔 is the minimum time required for the slurry rejection, in h; Q 泵 is the discharge of the grout pump used during the slurry rejection, in m 3 / h.

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