Grouting method for regulating and controlling pressure of high-pressure water gushing grouting orifice

Abstract

The invention discloses a high-pressure water gushing grouting orifice pressure regulation grouting method, which relates to the technical field of grouting plugging, and comprises the following steps: step 1, firstly carrying out water gushing characteristic analysis; step 2, calculating the required use amount of the slurry with the viscosity time-varying characteristic and the slurry replacement water; step 3, carrying out a viscosity time-varying characteristic slurry test; fourthly, an orifice grouting isolation device is installed, and an isolation plug is installed in an isolation plug cavity; 5, the viscosity time-varying slurry is injected from the grouting opening, pressure grouting is conducted through a pressure control device, and the pressure of the opening is monitored; sixthly, after the required cement-based viscosity time-varying grout is completely injected, the isolation plug is installed in the isolation plug cavity again, after installation is completed, required grout replacement water starts to be injected, and the pressure of a hole opening is monitored; and step 7, observing the pressure gauge, and judging the fracture condition and the grouting effect according to the pressure change of the orifice. The construction link is convenient and simple, the plugging effect is good, and the grouting effect can be evaluated in real time.

Description

Technical Field

[0001] The present invention belongs to the technical field of grouting plugging, and particularly relates to a grouting method for regulating the orifice pressure of high-pressure water inrush grouting holes. Background Art

[0002] When excavation construction is carried out in deep-buried high-pressure water-rich strata or karst strata, the situation of water inrush or seepage at the working face often occurs. If the water inrush points and rock fissures are not blocked in time, it will endanger the safety of construction workers and equipment at least, and cause casualties and direct economic losses at worst. In extreme cases, it will cause a chain reaction of environmental damage: excessive water inrush will lead to a drop in the groundwater level, causing surface subsidence and seriously affecting the production and life of surrounding residents. In order to avoid the occurrence of the above situations, the grouting method is often used during the construction process to control the water inrush situation.

[0003] The grouting method, as the name implies, is to inject a plugging slurry into the pores of the rock formation to change the permeability of some sections of the rock formation on the water filling path of the ore deposit, so as to achieve the effect of water stoppage. The common grouting method will mix and stir the cement slurry and water glass prepared in advance according to a certain ratio, and then transport them to the grouting pipe through a grouting pump for grouting. After reaching the designed grouting pressure or grouting volume, the grouting is stopped. After the pipe is removed and sealed, the grouting effect is inspected and accepted.

[0004] Generally, the judgment of the type of drilling water inrush channel mainly depends on the core structure and downhole video. However, for high-pressure water inrush drill holes, the high water inrush pressure makes it difficult to put the probe in, resulting in relatively difficult judgment of fissures. When carrying out the grouting water plugging operation for high-pressure water inrush, due to the large water pressure of the groundwater in the rock formation, under the action of the strong water pressure, part or even all of the injected plugging slurry will be washed away by the water flow, resulting in a situation where it is difficult to form, seriously affecting the working efficiency of grouting water plugging. Moreover, the plugging slurry often cannot solidify at the expected position, and it is difficult to completely seal the water outlet hole, resulting in a poor actual plugging effect. In addition, according to the current "Grouting Technology Code YS / T5211-2018", the evaluation of the grouting effect is usually carried out after the slurry solidifies and stabilizes, using means such as excavation, core drilling, and geophysical exploration, mainly based on the deformation monitoring results, combined with methods such as checking construction records, inspections, and tests for comprehensive evaluation. This evaluation often has hysteresis and subjectivity, and it is difficult to objectively and real-time evaluate the grouting effect. Summary of the Invention

[0005] The object of the present invention is to provide a grouting method for regulating the orifice pressure of high-pressure water gushing grouting holes, using viscosity-time-varying slurry as the grouting material to achieve grouting plugging under the conditions of high-pressure water gushing operations. At the same time, the type of water gushing channel is judged according to the change of the orifice pressure during the grouting process, and the grouting effect is evaluated in real time, so as to construct a complete system from the accurate determination of the high-pressure water gushing channel category to the simplified construction of the grouting operation and then to the real-time and objective evaluation of the final grouting effect.

[0006] To achieve the above object, the present invention provides a grouting method for regulating the orifice pressure of high-pressure water gushing grouting holes, and the specific implementation steps are as follows:

[0007] Step 1, first analyze the water gushing characteristics;

[0008] Step 2, calculate the required amount of viscosity-time-varying slurry and displacement water;

[0009] Step 3, conduct an experiment on the viscosity-time-varying slurry;

[0010] Step 4, install an orifice grouting isolation device and install an isolation plug in the isolation plug cavity;

[0011] Step 5, inject the viscosity-time-varying slurry from the grouting port and conduct pressure grouting through a pressure control device, and monitor the orifice pressure;

[0012] Step 6, when the required cement-based viscosity-time-varying slurry is completely injected, install an isolation plug in the isolation plug cavity again. After the installation is completed, start injecting the required displacement water and monitor the orifice pressure;

[0013] Step 7, observe the pressure gauge, and according to the change of the orifice pressure, the fracture situation and the grouting effect can be judged.

[0014] Preferably, in Step 1, according to different characteristics such as the borehole structure, hole depth, water gushing position, grouting plugging range, and solidified body strength, the slurry ratio, slurry rheology, and setting parameters used are determined through comprehensive consideration, and at the same time, the principles of "technically feasible, formation adaptable, and economically reasonable" should be satisfied.

[0015] Preferably, the calculation of the amount of viscosity-time-varying slurry in Step 2 should meet the following requirements:

[0016] a. When the water gushing pressure and water gushing volume in the borehole are large and carbonate crystals gush out, the grouting volume can be selected as 4 - 6 m 3 ; when the water gushing volume is small and there is no obvious gushing material, the grouting volume can be selected as 2 - 4 m 3 ;

[0017] b. If the water gushing volume and water gushing pressure in the borehole are not very large, but there are many water outlet points in the hole and the hole section is long, a larger grouting volume should also be selected;

[0018] c. When the drilling depth is large, the water gushing points are far apart, and the pressure and flow rate are high, 6 m of grouting volume can be selected. 3 of grouting volume.

[0019] The purpose of injecting displacement water is to inject the slurry in the pipeline and the inner casing of the hole into the crack, reducing the slurry loss and the re-drilling length of the subsequent hole.

[0020] Preferably, in step three, a slurry test with viscosity time-varying characteristics is carried out to determine whether the selected viscosity time-varying characteristic slurry ratio meets the requirements of the pumpable period and setting. The pumpable period should be calculated according to the following formula:

[0021] t = (V c + V w ) / Q + t0

[0022] In the formula: t - the pumpable period of the slurry (the grouting termination time), min; V c - the grouting volume, L; V w - the displacement water volume, L; Q - the grouting rate, L / m; t0 - the time occupied due to possible suspension and reduction of the pump volume during grouting, min.

[0023] Preferably, in step seven, during the grouting process, the process of slurry inflow and groundwater outflow follows the principle of mechanical equilibrium, that is, the grouting pressure is equal to the sum of the stresses of the slurry and water, which is equal to the water gushing pressure.

[0024] The equilibrium equation is:

[0025]

[0026] As the slurry is continuously injected, the slurry column pressure P c > P wb , and the grouting pressure remains unchanged at point 0; when the grouting liquid starts to enter the crack, the grouting pressure increases due to the influence of the change in the water-crossing section. This moment is called the "zero pressure end point". By analyzing the occurrence time of the "zero pressure end point" and the change rate of the grouting pressure, the type of water gushing channel can be judged. In addition, the channel crack and the grouting sealing effect can also be judged by the change in pressure during the injection of displacement water. The specific explanation is as follows:

[0027] (1) When the slurry starts to enter the crack, it will cause pressure fluctuations to generate the "zero pressure end point". The generation time of the zero pressure end point is related to the injection rate of the slurry, the cross-sectional area of the crack, and the liquid column pressure. Under ideal conditions, assuming that the slurry injection rate ≤ the cross-sectional flow rate, the slurry flows freely in the channel. At this time, when the total pressure of the slurry and the displacement water is equal to the water gushing pressure, the "zero pressure end" appears:

[0028]

[0029] When the slurry injection rate > cross-sectional flow rate, the zero end point is the starting time when the slurry enters the crack.

[0030] As the displacement water is injected, the grouting pressure continuously increases; when the grouting pressure rapidly rises or exceeds the water inrush pressure, it indicates a small-opening structural crack; when the growth rate of the grouting pressure = the previous decline rate, it indicates an open dissolution channel, and between the two is a medium-opening or mixed crack. After the grouting is completed, if the orifice pressure continuously rises but is significantly less than the water inrush pressure, it indicates that the water inrush crack is in a partially open state, that is, the grouting plays a plugging role but not completely; if the orifice pressure is close to the initial water inrush pressure, it indicates that the water inrush channel is completely open and the grouting has no effect; if the orifice pressure drops to 0 MPa, it indicates that as the slurry coagulates, the crack is completely plugged.

[0031] (2) If the drilling depth h < the balance height h cp , there will be no "pressure zero end point" and the lowest point will appear on the pressure curve. After that, the pressure change characteristics are basically the same as those of the above "pressure zero end point".

[0032] Therefore, the present invention adopts the above-mentioned method for controlling the grouting by the orifice pressure of high-pressure water inrush grouting, which has the following advantages:

[0033] The construction link is convenient and simple: the present invention can directly judge the type of water inrush channel according to the change of the orifice pressure during the grouting process.

[0034] Good plugging effect: The present invention uses a viscosity-time-varying slurry as the grouting plugging material, and through the front-end isolated closed controllable grouting technology, the grouting plugging under the conditions of high-pressure water inrush operation can be realized.

[0035] The grouting effect can be evaluated in real time: The present invention can realize the real-time evaluation of the grouting effect according to the change of the orifice pressure during the grouting process. Description of the Drawings

[0036] The following describes the technical solution proposed by the present invention in more detail through the drawings and examples.

[0037] Figure 1 is the overall scheme flowchart of the present invention;

[0038] Figure 2 is the schematic diagram of the mechanical model of water inrush drilling grouting of the present invention;

[0039] Figure 3 is the schematic diagram of the change of grouting pressure with time of the present invention;

[0040] Figure 4 is the schematic diagram of the orifice grouting isolation device of the present invention;

[0041] Figure 5 is the diagram of the change of drilling grouting pressure in the embodiment of the present invention;

[0042] P - Grouting pressure, kPa; P wb - Water inrush pressure, kPa; P w - Water column pressure, kPa; P c - Slurry pressure, kPa; P 表 - Pressure gauge reading, kPa; P 表0 - Initial pressure gauge reading, kPa; h - Drilling depth, m; h c - Slurry height, m; h w - Water column height, m; ρ w - Water density, 1.0 g / cm 3 ; ρ c - Slurry density, 1.73 - 1.8 g / cm 3 ; q - Grouting rate, L / min; t - Grouting time, min; β - Drilling inclination angle, °.

[0043] 1 is the grouting port; 2 is the pressure gauge; 3 is the isolation plug; 4 is the isolation plug cavity; 5 is the slurry outlet; 6 is the gate valve; 7 is the secondary casing water outlet; 8 is the primary casing water outlet; 9 is the primary casing; 10 is the secondary casing. Specific implementation mode

[0044] The technical content of the present invention will be described in detail below in conjunction with the drawings and embodiments.

[0045] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the ordinary meanings understood by those of ordinary skill in the field to which the present invention pertains. The "first", "second" and similar terms used in the present invention do not denote any order, quantity or importance, but are only used to distinguish different components. The terms such as "including" or "comprising" mean that the elements or objects appearing before this word cover the elements or objects listed after this word and their equivalents, without excluding other elements or objects. The terms such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The terms such as "upper", "lower", "left", "right" are only used to represent relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0046] Please refer to Figure 1 , the present invention provides a method for regulating the grouting pressure at the orifice of a high-pressure water inrush grouting hole, including the following steps:

[0047] Step 1. First, analyze the characteristics of water inrush.

[0048] Step 2. Calculate the required amounts of the viscosity-time variable property slurry and displacement water.

[0049] Step 3: Conduct a slurry test on the time-varying viscosity characteristics.

[0050] Step 4: As Figure 4 , install the isolation plug 3 in the isolation plug cavity 4.

[0051] Step 5: Inject the time-varying viscosity slurry from the grouting port 1, and perform pressure grouting through the pressure control device. Monitor the orifice pressure through the pressure gauge 2.

[0052] Step 6: After the required cement-based time-varying viscosity slurry is completely injected, install the isolation plug 3 in the isolation plug cavity 4 again. After the installation is completed, start injecting the required displacement water, and monitor the orifice pressure through the pressure gauge 2.

[0053] Step 7: Observe the pressure gauge 2. According to the change of the orifice pressure, the fracture condition and the grouting effect can be judged. The mechanical structure model is as Figure 2 .

[0054] According to the above steps, grouting operations were carried out on three grouting ports, and the change of the grouting pressure in the borehole was plotted as Figure 5 .

[0055] From Figure 5 , it can be seen that the initial pressure of borehole grouting is equal to the water inrush pressure at the orifice. As the slurry is injected, the grouting pressure continuously decreases, showing an approximate linear relationship with time. When the water inrush pressure is small or the borehole depth is deep enough, such as in grouting hole 1 and grouting hole 2, a pressure zero starting point appears, indicating that the sum of the slurry pressure and the water column pressure is equal to the water inrush pressure at this time. When grouting hole 1 was drilled, a pressure fluctuation occurred at 8 minutes of grouting, indicating that the slurry had entered the fracture at this time; after 20 minutes, as the displacement water was injected, the grouting pressure continued to rise to 0.15, indicating that the slurry continued to spread in the fracture under the action of the displacement water. The high grouting pressure after the grouting stopped indicates that the filling of the fracture by the slurry is incomplete and there is still a water inrush channel, causing the groundwater to erode the slurry. From this result, it can be inferred that there are multiple water inrush channels in this hole, and there are fractures with smaller openings in the upper part, resulting in a decrease in the slurry penetration rate and an increase in pressure; the diffusion of the slurry in the wider fractures in the lower part causes the grouting pressure to return to the pressure zero starting point.

[0056] A "pressure zero starting point" appeared in grouting hole 2 at 19 minutes. After injecting 2150 L of displacement water, a "pressure zero end point" appeared, as Figure 3 , and the pressure increased rapidly and stabilized at 2.0 MPa. This result shows that the flow of the slurry in the fracture is relatively smooth and the resistance is relatively small. The injection of the displacement water causes the slurry to quickly penetrate and be eroded by the groundwater, resulting in a rapid increase in the grouting force and approaching the initial pressure. This indicates that the fracture opening in the borehole is relatively large, possibly a large dissolution fracture or a dissolution channel.

[0057] The depth of grouting hole 3 is less than that of the balance pressure hole, so there is no "pressure zero starting point and end point". The fluctuating rise in pressure after reaching the lowest point indicates that the grout shows pulsating flow in the channel, that is, the crack opening remains unchanged. The decrease in pressure after the end of grouting indicates that the grout has achieved complete sealing of the crack, and the water inrush pressure is not sufficient to overcome the structural forces of the displacement water, grout, and the grout inside the crack. By the fluctuating rise in pressure after passing through the lowest point and the final decrease in pressure, it can be judged that the crack opening revealed by this borehole is small and there is no large-diameter corrosion channel.

[0058] For the three grouting holes in the embodiment, after the materials are completely solidified, the grouting effect is evaluated, and the specific results are as follows:

[0059] (1) Grouting hole 1

[0060] The actual grout injection volume of grouting hole 1 is 1800 L, and its water inrush volume is reduced from the initial 20 m 3 / h to about 5 m 3 / h, and the water inrush volume per unit time is reduced by 75%.

[0061] (2) Grouting hole 2

[0062] The grout injection volume of grouting hole 2 is 3200 L, and the displacement water injection volume is 2780 L. The actual grout volume entering the water inrush channel is 2930 L. 5 days after the end of grouting and hole sealing, there is still groundwater gushing out at the hole opening, and the water inrush volume is about 100 m 3 / h, which is basically the same as the initial water inrush volume, and the grouting water stoppage does not achieve the expected effect.

[0063] (3) Grouting hole 3

[0064] The actual grout injection volume of grouting hole 3 is 80% of the designed grouting volume, totaling 2000 L; the actual displacement water injection volume is 500 L of the designed value. The total grout volume finally entering the crack is 1518 L. 3 days after the end of grouting and hole sealing, there is no water gushing out at the hole opening.

[0065] The above results show that the present invention can achieve grouting plugging under the condition of high-pressure water inrush operation. In addition, although grouting hole 2 does not achieve the expected grouting water stoppage effect, the actual situation is basically consistent with the judgment of the crack type of the grouting hole and the evaluation of the grouting effect during grouting operation, which precisely shows that the present invention can accurately judge the crack type according to the pressure change at the hole opening during grouting and realize the real-time evaluation of the grouting effect.

[0066] Therefore, the present invention adopts the above-mentioned method for controlling the grouting hole pressure of high-pressure water gushing grouting, and the construction process is convenient and simple: the present invention can directly judge the type of water gushing channel according to the change of the hole pressure during the grouting process. Good plugging effect: the present invention uses the viscosity-time-varying slurry as the grouting plugging material, and through the front-end isolated closed controllable grouting technology, the grouting plugging under the condition of high-pressure water gushing operation can be realized. The grouting effect can be evaluated in real time: the present invention can realize the real-time evaluation of the grouting effect according to the change of the hole pressure during the grouting process.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A grouting method for regulating the orifice pressure of high-pressure water inrush grouting holes, characterized in that, It includes the following steps: Step 1: First, conduct an analysis of the water inrush characteristics; Step 2: Calculate the amounts of the viscosity-time-varying characteristic slurry and the displacement water required; Step 3: Conduct a test on the viscosity-time-varying characteristic slurry; Step 4: Install an orifice grouting isolation device and install an isolation plug in the isolation plug cavity; Step 5: Inject the viscosity-time-varying slurry from the grouting port and conduct pressure grouting through a pressure control device, and monitor the orifice pressure; Step 6: When all the required cement-based viscosity-time-varying slurry is completely injected, install an isolation plug in the isolation plug cavity again. After the installation is completed, start injecting the required displacement water and monitor the orifice pressure; Step 7: Observe the pressure gauge. Based on the change in the orifice pressure, the crack condition and the grouting effect can be judged.

2. The grouting method for controlling the orifice pressure of high-pressure water gushing grouting holes according to claim 1, characterized in that, In Step 1, according to different borehole structures, hole depths, water inrush positions, grouting plugging ranges, and solidified body strength characteristics, comprehensively consider and determine the slurry ratio, slurry rheology, and setting parameters to be used.

3. A pressure control grouting method for high-pressure water gushing grouting holes according to claim 1, characterized in that, The calculation of the amount of the viscosity-time-varying characteristic slurry in Step 2 shall meet the following requirements: a. When the water inrush pressure and water inrush volume during drilling are large and accompanied by the gushing out of carbonate crystals, the grouting volume is selected as 4 - 6 m 3 ; when the water inrush volume is small and there is no obvious gushing out material, the grouting volume is selected as 2 - 4 m 3 ; b. If the borehole water inrush volume and water inrush pressure are not very large, but there are many water outlet points in the hole and the hole section where they are distributed is relatively long, a larger grouting volume should also be selected; c. When the drilling depth is relatively large, the water gushing points are distributed at a long distance, and the pressure and flow rate are high, select a grouting volume of 6 m 3 .

4. A high-pressure water gushing grouting orifice pressure control grouting method according to claim 1, characterized in that, In Step 3, conduct a test on the viscosity-time-varying characteristic slurry to judge whether the selected viscosity-time-varying characteristic slurry ratio meets the requirements of the pumpable period and setting. The pumpable period shall be calculated according to the following formula: t = (V c + V w ) / Q + t0 Where: t - the pumpable period of the slurry, i.e., the grouting termination time, min; V c - the grouting volume, L; V w - the water volume for displacement, L; Q - the grouting rate, L / m; t0 - the time occupied due to suspension or reduction of the pump volume during grouting for some reasons, min.

5. A grouting method for regulating the orifice pressure of high-pressure water gushing grouting holes according to claim 1, characterized in that, In Steps 6 and 7, during the grouting process, the process of the slurry flowing in and the groundwater flowing out follows the principle of mechanical equilibrium, that is, the grouting pressure is equal to the sum of the stresses of the slurry and water. Its mechanical structure equilibrium equation is: As the slurry continues to be injected, the slurry column pressure P c > P wb , and the grouting pressure remains unchanged at the zero point; When the grouting liquid starts to enter the crack, the grouting pressure increases due to the influence of the change in the water passing section. This moment is called the "pressure zero end point"; by analyzing the occurrence time of the "pressure zero end point" and the change rate of the grouting pressure, the type of the water inrush channel can be judged; in addition, the crack of the channel and the grouting sealing effect can also be judged by the change in pressure during the process of injecting the displacement water; the specific explanations are as follows: (1) When the grouting liquid starts to enter the crack, it will cause pressure fluctuations to generate the "pressure zero end point"; the generation time of the zero end point is related to the injection rate of the slurry, the cross-sectional area of the crack, and the liquid column pressure; in the ideal state, assume that the injection rate of the slurry ≤ the cross-sectional flow rate, and the slurry flows freely in the channel. At this time, when the total pressure of the slurry and the displacement water is equal to the water inrush pressure, the "pressure zero" appears: When the injection rate of the slurry > the cross-sectional flow rate, the zero end point is the starting time when the slurry enters the crack; As the displacement water is injected, the grouting pressure continues to increase; when the grouting pressure rises rapidly or exceeds the water inrush pressure, it indicates a small-aperture tectonic crack; when the growth rate of the grouting pressure = the previous decline rate, it indicates an open-type dissolution channel; if it is between the two, it is a medium-aperture or mixed crack; after the grouting is completed, if the orifice pressure continues to rise but is significantly less than the water inrush pressure, it indicates that the water inrush crack is in a partially open state, that is, the grouting plays a plugging role but not completely; if the orifice pressure is close to the initial water inrush pressure, it indicates that the water inrush channel is completely open and the grouting has no effect; if the orifice pressure drops to 0 MPa, it indicates that the crack is completely plugged with the setting of the slurry; (2) If the drilling depth h < the equilibrium height h cp , then there will be no "pressure zero end point", and the lowest point will appear on the pressure curve; thereafter, the pressure change characteristics will be basically the same as those of the above-mentioned "pressure zero end point".

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