Construction method based on water curtain hole auxiliary cavern grouting seepage control

Abstract

The invention relates to the technical field of underground water-sealed cave depot engineering, and particularly discloses a construction method based on water curtain hole auxiliary cavern grouting seepage control, which comprises the following steps of: firstly, determining a potential water guide crack in advance through a water curtain hole drilling process, and providing a main basis for advanced exploring hole arrangement and grouting design; then, whether grouting treatment needs to be carried out or not is determined according to the water seepage condition of the advance exploring hole before rock mass excavation or the surrounding rock after excavation, and potential water guiding fracture plugging is carried out by optimizing and adjusting grouting hole arrangement; and finally, according to whether the daily water supplementing amount of the water curtain hole is recovered before excavation, grouting effect inspection is conducted. According to the method, the problems of blindness caused by uncertain water guide cracks in existing underground cavern grouting construction, uncertainty caused by single effect evaluation indexes and the like are solved, the water curtain hole construction investigation function and long-term water replenishing monitoring data are fully played, the pertinence of cavern grouting water plugging and the reasonability of effect inspection are remarkably improved, and the construction efficiency is improved. And the grouting construction efficiency is guaranteed, and important engineering application value is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of underground water-sealed cavern engineering, and in particular to a construction method based on water curtain hole-assisted cavern grouting seepage control. Background Art

[0002] Underground water-sealed caverns are artificially excavated in hard rock below a stable groundwater level to form a cavern of a certain volume for storing refined oil, liquefied petroleum gas, and other products. The technology uses design to control groundwater flowing into the oil depot through cracks in the surrounding rock to achieve sealed oil storage. Underground water-sealed caverns are mainly composed of oil storage caverns, a water curtain system, connecting tunnels, and auxiliary caverns. The oil storage caverns are used to store crude oil. The water curtain system includes water curtain tunnels, water curtain holes, and a water supply system. It is located approximately 25 meters above the vault of the oil storage caverns. The water curtain holes are parallel to the axis of the oil storage caverns and cover the entire area above the oil storage caverns. Water curtain water replenishment ensures that the rock mass around the caverns is always saturated, meeting the cavern water seal requirements and preventing oil and gas leakage. The connecting tunnels and auxiliary caverns provide transportation and maintenance channels.

[0003] Underground water-sealed caverns rely on a certain groundwater pressure to seal oil storage while minimizing groundwater seepage into the cavern, aiming for the ideal "seepage without leakage" state. Therefore, water seal effectiveness and water seepage control are key technical challenges in water-sealed cavern construction. During cavern construction, targeted grouting is an important means of achieving both water sealability and water seepage control. While existing grouting technologies have made progress in design, construction, and performance evaluation, significant challenges remain, such as the concealed nature of grouting, complex mechanisms, and difficulty in evaluating performance. Consequently, low grouting efficiency and suboptimal seepage control have consistently hindered the smooth construction of water-sealed caverns. Given that water curtain holes are constructed ahead of the main cavern and fully cover the area above the oil storage cavern, the geological information revealed by drilling and the rock permeability characteristics reflected by changes in water replenishment are crucial for guiding grouting seepage control design. However, current grouting construction for water-sealed caverns has not fully utilized the role of water curtain hole surveys and permeability evaluations, leaving room for improvement.

[0004] To this end, the present application provides a construction method based on water curtain hole assisted cavern grouting seepage control to solve the problems of blind grouting construction and single effect evaluation index. Summary of the Invention

[0005] The purpose of the present invention is to provide a construction method based on water curtain hole assisted cavern grouting seepage control to solve the problems existing in the above-mentioned prior art.

[0006] To achieve the above object, the present invention provides a construction method based on water curtain hole assisted cavern grouting seepage control, comprising the following steps:

[0007] Identify potential water-conducting fractures through water curtain hole drilling process information; and arrange advance exploration holes before underground cavern excavation to explore the water-bearing environment of the rock mass ahead;

[0008] When the underground cavern is excavated near potential water-conducting fissures, the layout of advance exploration holes is optimized according to the occurrence characteristics of the water-conducting fissures;

[0009] Based on the water seepage per meter of the advance exploration hole, determine whether pre-grouting is necessary and whether additional advance exploration holes are needed to further clarify the water supply of the rock mass ahead. Based on the changes in the daily water supply of the water curtain hole, determine the hydraulic connection between the water-conducting fractures in the rock mass ahead and the water curtain hole.

[0010] If pre-grouting is required, the pre-grouting effect should be inspected after completion. After the pre-grouting effect is qualified, the rock mass in front of the tunnel face can be excavated.

[0011] If pre-grouting is not required, excavation is directly carried out on the rock mass in front of the tunnel face; the tunnel face is the working surface where the cavern excavation continuously advances forward;

[0012] After rock mass excavation, determine whether the water seepage in the surrounding rock exceeds the standard;

[0013] If the surrounding rock seepage does not exceed the standard, the next stage of excavation construction will begin;

[0014] If the water seepage of the surrounding rock exceeds the standard, for the concentrated water seepage points of the surrounding rock exposed after rock excavation, the hydraulic connection between the water seepage points and the water curtain holes shall be judged according to the changes in the daily water replenishment of the water curtain holes, and post-grouting measures shall be implemented in the concentrated water seepage areas of the surrounding rock to seal the water seepage points; after the post-grouting construction is completed, the post-grouting effect shall be tested; if the post-grouting effect test is qualified, the next stage of excavation construction shall be started.

[0015] Preferably, the water curtain hole drilling process information includes drilling speed, backwater color and water output, drill sticking, and in-hole TV imaging, and the formation lithology, distribution position and occurrence characteristics of water-conducting fractures are determined based on the water curtain hole drilling process information.

[0016] Preferably, the water curtain holes arranged above the underground cavern are not less than 25m away from the underground cavern, the axial direction of the water curtain holes is parallel to the axial direction of the underground cavern, the distance between two adjacent water curtain holes is not more than 10m, and the aperture of the water curtain holes is 115mm.

[0017] Preferably, optimizing the arrangement of the advance exploration holes includes optimizing the positions and angles of the advance exploration holes so that the advance exploration holes intersect with potential water-conducting fractures at a large angle.

[0018] Preferably, the number of advance exploration holes is not less than 3.

[0019] Preferably, the conditions for determining whether pre-grouting is required are as follows:

[0020] When the water seepage per meter of the advance exploration hole q<q1, no pre-grouting is carried out;

[0021] When q1<q<10q1, after grouting and plugging the advance exploration hole, replace the advance exploration hole at other locations and perform pre-grouting control;

[0022] When q≥10q1, pre-grouting is performed on the rock mass in front of the tunnel face;

[0023] q1 is the pre-grouting threshold determined according to the rock permeability and groundwater pressure.

[0024] Preferably, the pre-grouting construction includes:

[0025] Drill pre-grouting holes, which are arranged along the perimeter of the tunnel face;

[0026] The layout of the pre-grouting holes is optimized according to the occurrence characteristics of the water-conducting fissures determined by the water curtain holes. The optimization of the layout of the pre-grouting holes includes optimizing the hole depth, position, outward swing angle, and hole spacing of the pre-grouting holes so that the pre-grouting holes pass through the potential water-conducting fissures at a large angle.

[0027] Preferably, the inspection method for the pre-grouting effect inspection includes:

[0028] Inspection holes are arranged on the tunnel face, and the grouting effect is evaluated by testing the permeability of the rock mass after grouting through a water pressure test.

[0029] Preferably, the pre-grouting effect test method also includes:

[0030] The pre-grouting effect is tested by comparing the change of the current daily water replenishment volume Q2 of the water curtain hole with the daily water replenishment volume Q0 of the water curtain hole before grouting construction.

[0031] Preferably, the inspection method of the post-grouting effect inspection is the same as the inspection method of the pre-grouting effect inspection.

[0032] Compared with the prior art, the present invention has the following advantages and technical effects:

[0033] The construction method for seepage control based on water curtain hole-assisted cavern grouting provided by the present invention comprises the following steps: first, potential water-conducting fissures are determined in advance during the water curtain hole drilling process, so as to give full play to the construction survey role of the water curtain hole and provide a main basis for the arrangement of advance exploration holes and grouting design; then, whether grouting treatment is needed is determined based on the seepage conditions of the advance exploration holes before rock mass excavation or the surrounding rock after excavation; the hydraulic connection between the seepage point and the water curtain hole is determined based on the change of the daily water replenishment volume of the water curtain hole; the potential water-conducting fissures are sealed by optimizing and adjusting the grouting hole arrangement, so as to reduce the overall permeability of the rock mass and create good construction conditions for the next cycle of excavation; finally, the grouting effect is tested based on whether the daily water replenishment volume of the water curtain hole has recovered to the level before excavation.

[0034] This invention addresses the problems of blindness in existing underground cavern grouting construction due to unclear water-conducting fissures and uncertainty caused by a single effect evaluation indicator. It leverages the relative position of underground engineering structures to provide a basis for grouting design and effect testing. Leveraging the construction survey of water curtain holes and long-term water replenishment monitoring data, this invention significantly improves the pertinence of cavern grouting and the rationality of effect testing, ensuring grouting construction efficiency and possessing significant engineering application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0036] Figure 1 This is a flow chart of the construction method of the present invention based on water curtain hole assisted cavern grouting seepage control;

[0037] Figure 2 A distribution diagram of the main structures of the underground caverns provided by the present invention;

[0038] Figure 3 The embodiments of the present invention provide water curtain hole survey information, advance exploration hole and grouting hole layout, and water curtain hole daily water replenishment monitoring data. DETAILED DESCRIPTION

[0039] It should be noted that, unless there is a conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other. The embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention. The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0040] like Figure 1 As shown, the present invention provides a construction method based on water curtain hole assisted cavern grouting seepage control, comprising the following steps:

[0041] Potential water-conducting fractures are identified through the drilling process information of water curtain holes, including drilling speed, backwater color and water output, drill sticking, and in-hole television imaging, thereby judging the lithology of the stratum, the distribution location and occurrence characteristics of water-conducting fractures; water curtain holes are drilled for water injection to meet the water sealing conditions of the cavern. They are generally constructed at least 20 meters ahead of the underground cavern below them and are located 25 meters above the underground cavern vault. The axis of the water curtain holes is parallel to the axis of the cavern, the spacing between the water curtain holes is generally no more than 10 meters, and the hole diameter is about 115 mm.

[0042] When the underground cavern is excavated near potential water-conducting fissures, the current daily water replenishment Q0 of the water curtain hole above the area is recorded. The layout of the advance exploration holes is optimized according to the characteristics of the water-conducting fissures, including the position and angle of the advance exploration holes, so that they intersect with the potential water-conducting fissures at a large angle to achieve the purpose of effective advance water exploration. The advance exploration holes are holes drilled before the cavern is excavated to explore the water-bearing environment of the rock mass ahead, and the number is generally not less than 3.

[0043] Based on the water seepage per linear meter of the advance exploration hole, determine whether pre-grouting is necessary and whether additional advance exploration holes need to be drilled to further clarify the water content of the rock mass ahead. Pre-grouting is a grouting measure implemented along the axial direction of the cavern at potential water seepage locations before rock excavation. When the water seepage per linear meter of the advance exploration hole q < q1, pre-grouting is not required; when q1 < q < 10q1, the advance exploration hole needs to be grouted and sealed, and then additional advance exploration holes need to be drilled at other locations, and pre-grouting control should be carried out according to this condition; when q ≥ 10q1, pre-grouting of the rock mass ahead of the tunnel face is required. q1 is the pre-grouting threshold determined based on the permeability of the rock formation and groundwater pressure. When the water seepage per linear meter of the advance exploration hole is large, it is necessary to closely monitor the changes in the daily water replenishment of the water curtain holes above this area. If the daily water replenishment of the water curtain hole increases significantly to Q1, it means that the seepage point revealed by the advance exploration hole has a clear hydraulic connection with the water curtain hole; if the daily water replenishment of the water curtain hole does not change significantly, it means that the hydraulic connection is weak.

[0044] Pre-grouting construction should first involve drilling pre-grouting holes. The pre-grouting holes should be arranged along the perimeter of the tunnel face, and the hole layout should be optimized according to the characteristics of the water-conducting fissures determined by the water curtain holes, including hole depth, position, outward swing angle, and hole spacing. The pre-grouting holes should pass through potential water-conducting fissures at a large angle, and the pre-grouting holes should be appropriately arranged densely within the influence range of the water-conducting fissures to expand the slurry diffusion range as much as possible, improve the grouting efficiency, and effectively seal the water-conducting fissures.

[0045] After pre-grouting is complete, the grouting effect needs to be tested. In addition to placing inspection holes on the tunnel face and evaluating the post-grouting permeability of the rock mass through water pressure tests, the pre-grouting effect can also be verified by comparing the current daily water replenishment volume Q2 of the water curtain holes with the daily water replenishment volume Q0 before grouting. If Q2 returns to or approaches Q0 after grouting, it indicates that the grouting effect is good and the impact of cavern excavation on rock permeability has been reduced to a low level. If Q2 is still significantly greater than Q0, it indicates that the grouting effect is poor, and further reinforcement grouting measures are necessary to further reduce the permeability of the surrounding rock. The tunnel face is the working surface where cavern excavation continues to advance.

[0046] Excavation of the rock mass in front of the tunnel face can only be carried out after the pre-grouting effect has been tested and found to be qualified.

[0047] For concentrated water seepage points in the surrounding rock exposed after rock mass excavation, including water seepage from anchor holes and fissures, it is necessary to determine the hydraulic connection between the surrounding rock seepage points and the water curtain holes based on the daily water replenishment changes in the corresponding area. Post-grouting measures should be implemented in the concentrated water seepage areas to seal the water seepage points. Post-grouting is the drilling and grouting of the exposed rock surface at the water seepage areas exposed on the rock mass surface after rock mass excavation.

[0048] After the post-grouting construction is completed, the grouting effect needs to be tested, referring to the above-mentioned pre-grouting effect test method.

[0049] When the post-grouting effect test is qualified, there is no obvious water seepage in the surrounding rock of the cavern or the total water seepage is lower than the seepage control technical requirements, the next stage of excavation construction can be arranged.

[0050] like Figure 2 As shown in the figure, the main structure of the underground cavern includes the oil storage cavern 1, the water curtain tunnel 2, and the water curtain hole 3. Figure 2 (a) From the top view, it can be seen that the axis of the oil storage cavern 1 is perpendicular to the axis of the water curtain roadway 2. The water curtain hole 3 is constructed in the water curtain roadway 2, generally at least 20m ahead of the oil storage cavern 1 below it. The water curtain hole 3 is parallel to the axis of the oil storage cavern 1 and completely covers the entire area above the oil storage cavern 1. Figure 2 (b) The side view shows that the water curtain tunnel 2 is above the oil storage cavern 1, with a cross-section height of 6m and a span of 7m. The water curtain holes 3 are evenly distributed in the water curtain tunnel 2, with a spacing of generally 10m. The water curtain holes 3 are drilled and constructed on the side wall about 1m above the bottom plate of the water curtain tunnel 2. The cross-section span of the oil storage cavern 1 is 20m and the height is 30m. It is generally constructed by layered excavation. Figure 2 (c) From the side view, it can be seen that the bottom plate of water curtain tunnel 2 is 25m away from the arch of oil storage cavern 1.

[0051] Example

[0052] See also Figure 3 In this example, when the upper layer of a certain oil storage cavern is excavated to the pile number K0+799 on July 5, 2023, it is close to the S3 alteration zone with a strike of 60°∠70°~80° determined by the preliminary investigation of the water curtain hole. Continuing excavation will cause water leakage risk. Figure 3 (a) By optimizing the layout of the advanced exploration holes on the tunnel face, adjusting their positions and angles so that they intersect with the S3 alteration zone at a large angle, as shown in Figure 3 As shown in (b), after the advance drilling was completed, the water seepage rate reached 75L / min, and then the daily water replenishment of the water curtain holes E215-E218 above the oil storage cavern increased significantly (Q1), among which the daily water replenishment of the water curtain hole E216 increased by 72m 3 / d, an increase of 227.83% compared with the previous period, indicating that there is a strong hydraulic connectivity between the seepage point of the advance exploration hole and the water curtain hole through the S3 alteration zone, such as Figure 3 As shown in (c), the water seepage of the advance exploration hole far exceeds the pre-grouting control standard. According to the occurrence characteristics of the S3 alteration zone, the layout of the pre-grouting holes is optimized, so that the grouting holes intersect with the S3 alteration zone at a large angle, expanding the slurry diffusion range and achieving efficient water blocking. Figure 3 As shown in (d), the grouting construction of the tunnel face started on July 6, 2023, and was completed on July 9. The daily water replenishment of the water curtain hole was significantly reduced and basically returned to the initial level (Q2≈Q0), indicating that the grouting construction was relatively effective and the seepage control effect was good. On July 10, 2023, the rock mass excavation and support in front of the tunnel face were completed. There was no obvious water seepage in the surrounding rock in the cavern and the water curtain replenishment volume tended to be stable. The next stage of excavation can be carried out. Figure 3 (c) shown.

[0053] The construction method provided by the present invention, which uses water curtain holes to assist in cavern grouting and seepage control, utilizes the characteristics of water curtain holes that fully cover the oil storage cavern and are ahead of the oil storage cavern construction, and determines potential water-conducting fissures through information on the water curtain hole drilling process. Regarding the situation before rock mass excavation, when the face approaches potential water-conducting fissures, the layout of advance exploration holes should be promptly optimized based on the occurrence of potential water-conducting fissures to achieve the purpose of efficient water exploration. When the seepage of the advance exploration holes exceeds the standard, the hydraulic connectivity between the seepage point and the water curtain hole is determined based on the change in the daily water replenishment of the water curtain hole, and then pre-grouting is implemented on the rock mass to be excavated. The occurrence of potential water-conducting fissures can provide a basis for optimizing the layout of grouting holes, avoiding blind grouting construction and achieving precise grouting and water blocking. Regarding the situation where the seepage of the surrounding rock of the cavern exceeds the standard after rock mass excavation, the hydraulic connectivity between the seepage point and the water curtain hole is determined based on the change in the daily water replenishment of the water curtain hole, and post-grouting is implemented on the seepage area on the rock mass surface exposed by excavation. After the grouting construction is completed, the grouting effect is tested based on the changes in the daily water replenishment volume of the water curtain holes, providing a reasonable and scientific basis for the evaluation of the seepage control effect.

[0054] The above are only preferred specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or replacements that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A construction method based on water curtain hole assisted cavern grouting seepage control, characterized in that: The following steps are involved: Identify potential water-conducting fractures through water curtain hole drilling process information; and arrange advance exploration holes before underground cavern excavation to explore the water-bearing environment of the rock mass ahead; When the underground cavern is excavated near potential water-conducting fissures, the layout of advance exploration holes is optimized according to the occurrence characteristics of the water-conducting fissures; Based on the water seepage per meter of the advance exploration hole, determine whether pre-grouting is necessary and whether additional advance exploration holes are needed to further clarify the water supply of the rock mass ahead. Based on the changes in the daily water supply of the water curtain hole, determine the hydraulic connection between the water-conducting fractures in the rock mass ahead and the water curtain hole. If pre-grouting is required, the pre-grouting effect should be inspected after completion. After the pre-grouting effect is qualified, the rock mass in front of the tunnel face can be excavated. If pre-grouting is not required, excavation is directly carried out on the rock mass in front of the tunnel face; the tunnel face is the working surface where the cavern excavation continuously advances forward; After rock mass excavation, determine whether the water seepage in the surrounding rock exceeds the standard; If the surrounding rock seepage does not exceed the standard, the next stage of excavation construction will begin; If the water seepage of the surrounding rock exceeds the standard, for the concentrated water seepage points of the surrounding rock exposed after rock excavation, the hydraulic connection between the water seepage points and the water curtain holes shall be judged according to the changes in the daily water replenishment of the water curtain holes, and post-grouting measures shall be implemented in the concentrated water seepage areas of the surrounding rock to seal the water seepage points; after the post-grouting construction is completed, the post-grouting effect shall be tested; if the post-grouting effect test is qualified, the next stage of excavation construction shall be started.

2. The construction method based on water curtain hole assisted cavern grouting seepage control according to claim 1 is characterized in that: The information of the water curtain hole drilling process includes drilling speed, backwater color and water output, drill sticking, and in-hole TV imaging. The lithology, distribution location and occurrence characteristics of water-conducting fractures can be judged based on the information of the water curtain hole drilling process.

3. The construction method based on water curtain hole assisted cavern grouting seepage control according to claim 1 is characterized in that: The water curtain holes arranged above the underground caverns shall be no less than 25m away from the underground caverns, the axis of the water curtain holes shall be parallel to the axis of the underground caverns, the distance between two adjacent water curtain holes shall not exceed 10m, and the aperture of the water curtain holes shall be 115mm.

4. The construction method based on water curtain hole assisted cavern grouting seepage control according to claim 1 is characterized in that: Optimizing the layout of advance exploration holes includes optimizing the position and angle of the advance exploration holes so that the advance exploration holes intersect with potential water-conducting fractures at a large angle.

5. The construction method based on water curtain hole assisted cavern grouting seepage control according to claim 1 is characterized in that: The number of advance exploration holes shall not be less than 3.

6. The construction method based on water curtain hole assisted cavern grouting seepage control according to claim 1 is characterized in that: The conditions for judging whether pre-grouting is required are as follows: When the water seepage per meter of the advance exploration hole q<q1, no pre-grouting is carried out; When q1<q<10q1, after grouting and plugging the advance exploration hole, replace the advance exploration hole at other locations and perform pre-grouting control; When q≥10q1, pre-grouting is performed on the rock mass in front of the tunnel face; q1 is the pre-grouting threshold determined according to the rock permeability and groundwater pressure.

7. The construction method based on water curtain hole assisted cavern grouting seepage control according to claim 1 is characterized in that: Pre-grouting construction includes: Drill pre-grouting holes, which are arranged along the perimeter of the tunnel face; The layout of the pre-grouting holes is optimized according to the occurrence characteristics of the water-conducting fissures determined by the water curtain holes; the optimization of the layout of the pre-grouting holes includes optimizing the hole depth, position, outward swing angle, and hole spacing of the pre-grouting holes, so that the pre-grouting holes pass through the potential water-conducting fissures at a large angle.

8. The construction method based on water curtain hole assisted cavern grouting seepage control according to claim 1 is characterized in that: The inspection methods for pre-grouting effect inspection include: Inspection holes are arranged on the tunnel face, and the grouting effect is evaluated by testing the permeability of the rock mass after grouting through a water pressure test.

9. The construction method based on water curtain hole assisted cavern grouting seepage control according to claim 1 is characterized in that: The inspection methods for pre-grouting effect inspection also include: The pre-grouting effect is tested by comparing the change of the current daily water replenishment volume Q2 of the water curtain hole with the daily water replenishment volume Q0 of the water curtain hole before grouting construction.

10. The construction method based on water curtain hole assisted cavern grouting seepage control according to claim 1 is characterized in that: The inspection method for post-grouting effect inspection is the same as that for pre-grouting effect inspection.

Images