An excavation construction method for stabilizing a tunnel face in a water-rich stratum

Abstract

The application discloses a kind of water-rich stratum tunnel stable face of excavation construction method, comprising the following steps: step S1, according to the vertical division of multiple sub-faces of tunnel face of water content different;Step S2, determine the number of water guide hole drilled in each sub-face, then drill;Step S3, after water guide hole on each sub-face is discharged for a period of time;Step S4, again using excavating equipment to excavate tunnel, step S5, repeat above-mentioned step S2-step S4, until the excavation of entire tunnel is completed.The application according to the water content of different position is different, and the sub-face is divided into multiple sub-faces with different water content, and then the number of water guide hole drilled in each sub-face is calculated and determined, so that the sub-face with different water content can be controlled for drainage, so that the pressure borne by the soil layer in front of the sub-face after drainage is relatively consistent, so that it can be ensured to avoid splitting due to inconsistent long-term pressure stress.

Description

Technical Field

[0001] This invention relates to the field of tunnel face excavation construction. More specifically, this invention relates to a method for excavating and constructing a stable tunnel face in water-rich strata. Background Technology

[0002] With the rapid development of railway transportation, tunnel excavation in different regions often encounters water-rich strata such as lakes and canals. Due to environmental factors, these strata experience high water pressure, and if not properly managed, tunnel excavation can easily lead to geological disasters such as water inrush and mudslides, subsequently causing instability of the surrounding rock. To avoid this problem, most methods involve installing drainage pipes to drain water, reduce water pressure, and then injecting grouting materials. While this method is simple and practical, the simplistic installation of drainage pipes may result in varying water pressures at different locations on the tunnel face, which can eventually lead to cracking and other problems. Summary of the Invention

[0003] To achieve these objectives and other advantages according to the present invention, a preferred embodiment of the present invention provides a method for excavating a stable tunnel face in water-rich strata, comprising the following steps:

[0004] Step S1: Detect the water content and rock strata conditions in front of the tunnel face, and divide the tunnel face vertically into multiple sub-faces according to the different water contents, and mark each sub-face separately.

[0005] Step S2: Based on the water content and rock strata of each working face, determine the number of water guide holes to be drilled at each working face. Then, use drilling equipment to drill holes at each working face to obtain the predetermined number of water guide holes. Use the water guide holes for drainage. The water guide holes are inclined from top to bottom.

[0006] Step S3: Wait for the water to drain from the guide holes on each face of the tunnel for a period of time;

[0007] Step S4: Use excavation equipment to excavate the tunnel again, and divide the pre-excavated tunnel into multiple sub-tunnel segments along its length. Excavate the multiple sub-tunnel segments in sequence, and for each sub-tunnel segment, keep the excavation order from the two side face to the middle face. After each face is excavated, apply a layer of concrete to its top surface.

[0008] Step S5: Repeat steps S2-S4 above until the excavation of the entire tunnel is completed.

[0009] According to a preferred embodiment of the present invention, in the excavation construction method for a stable tunnel face in water-rich strata, the more water guide holes are opened on the tunnel face with higher water content.

[0010] According to a preferred embodiment of the present invention, in the excavation construction method for a stable tunnel face in water-rich strata, step S3, after the water guide holes on each sub-face have discharged water for a period of time, further includes the following operation:

[0011] The soil strength equipment is used to test the strength of the soil layer at a certain distance in front of each working face. Based on the different strengths of the soil layer in front of each working face, the amount of grouting material required per cubic meter of soil layer to achieve the same strength is calculated. The corresponding amount of grouting material is then injected into each working face according to the calculated amount. After the grouting material has completely hardened, the subsequent step S4 is carried out.

[0012] According to a preferred embodiment of the present invention, in the excavation construction method for a stable tunnel face in a water-rich stratum, in step S3, after the grouting material is injected, when the grouting material hardens to a preset hardness, the soil strength of the soil layer at a certain distance in front of each sub-face is tested again using a soil strength device. If the strength of one sub-face is less than the average value of the strength of all sub-faces within a certain range, grouting material is injected into that sub-face. When the grouting material of that sub-face hardens to a preset hardness, the soil strength device is tested again, and the strength is compared with the strength of other sub-faces when the grouting material is at the preset hardness. The above operation is repeated until the strength of each low-strength area is within the average value range.

[0013] The preset hardness is less than the hardness of the grouting material when it is fully hardened.

[0014] According to a preferred embodiment of the present invention, in the excavation construction method for a stable tunnel face in water-rich strata, during the excavation process, support devices can be installed on adjacent face sections of the face section being excavated.

[0015] According to a preferred embodiment of the present invention, in the excavation construction method for a stable tunnel face in water-rich strata, grouting material is injected into the coating in front of the tunnel face using grouting anchor rods, and during the grouting process, fixed anchor rods are used to anchor the material into the soil layer for fixation.

[0016] According to a preferred embodiment of the present invention, in the excavation construction method for a stable tunnel face in water-rich strata, multiple injection holes are opened on the front end and sidewall of the fixed anchor rod.

[0017] According to a preferred embodiment of the present invention, in the excavation construction method for a stable tunnel face in water-rich strata, the concrete is high-strength concrete.

[0018] According to a preferred embodiment of the present invention, in the excavation construction method for a stable tunnel face in a water-rich stratum, in step S3, after the grouting material has completely hardened, a thin layer of concrete is sprayed onto the top of the tunnel face. After the thin layer of concrete hardens, it can be excavated and crushed.

[0019] According to a preferred embodiment of the present invention, in the excavation construction method for a stable tunnel face in a water-rich stratum, in step S3, the grouting holes of the grouting anchors are all covered by sealing plates. The sealing plates are made of flexible material, and the shape and size of the sealing plates and the grouting holes are adapted to each other, both being circular. The sealing plates are divided into multiple triangular plates by multiple central axes.

[0020] The present invention has at least the following beneficial effects: Instead of using the conventional method of uniformly setting drainage pipes and injecting grouting materials, the present invention divides the working face into multiple sub-faces with different water contents based on the varying moisture content at different locations. Then, based on the moisture content and rock strata conditions of each sub-face, the number of water-conducting holes required for each sub-face is calculated and determined. Drilling is then performed on each sub-face according to the calculated number of water-conducting holes. This allows for drainage control at sub-faces with different moisture contents, ensuring that the soil layer in front of the drained sub-face experiences more consistent pressure, thus preventing cracking caused by long-term inconsistent pressure stress.

[0021] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to embodiments, so that those skilled in the art can implement it based on the description.

[0023] The following description is intended to disclose the present invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious modifications will occur to those skilled in the art. The basic principles of the invention defined in the following description can be applied to other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the invention.

[0024] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.

[0025] During tunnel construction in water-rich strata, drainage pipes are typically installed to drain water and reduce water pressure. However, this simple and indiscriminate installation of drainage pipes can lead to uneven water pressure at different locations on the tunnel face, potentially causing cracking and other problems over time. To address this technical issue, a preferred embodiment of the present invention provides a method for excavating and constructing a stable tunnel face in water-rich strata, comprising the following steps:

[0026] Step S1: Detect the water content and rock strata conditions in front of the tunnel face, and divide the tunnel face vertically into multiple sub-faces according to the different water contents, and mark each sub-face separately.

[0027] Step S2: Based on the water content and rock strata of each working face, determine the number of water guide holes to be drilled at each working face. Then, use drilling equipment to drill holes at each working face to obtain the predetermined number of water guide holes. Use the water guide holes for drainage. The water guide holes are inclined from top to bottom.

[0028] Step S3: Wait for the water to drain from the guide holes on each face of the tunnel for a period of time;

[0029] Step S4: Use excavation equipment to excavate the tunnel again, and divide the pre-excavated tunnel into multiple sub-tunnel segments along its length. Excavate the multiple sub-tunnel segments in sequence, and for each sub-tunnel segment, keep the excavation order from the two side face to the middle face. After each face is excavated, apply a layer of concrete to its top surface.

[0030] Step S5: Repeat steps S2-S4 above until the excavation of the entire tunnel is completed.

[0031] The above implementation scheme does not adopt the conventional approach of uniformly setting up drainage pipes and uniformly injecting grouting materials. Instead, it divides the working face into multiple sub-faces with different water contents based on the different locations. Then, based on the water content and rock strata conditions of each sub-face, it calculates and determines the number of water guide holes to be drilled for each sub-face. Drilling is then carried out on each sub-face according to the calculated number of water guide holes. This allows for drainage control on sub-faces with different water contents, ensuring that the soil layer in front of the sub-face faces more uniformly after drainage. This can prevent cracking caused by long-term inconsistent pressure stress.

[0032] Grouting materials are fluid materials that, under pressure, are injected into cracks or cavities in strata, rocks, or structures to increase load-bearing capacity, prevent leakage, and improve the overall performance of the structure. They are capable of solidification. No restrictions are placed on the type of grouting material; any commercially available conventional building grouting material is acceptable.

[0033] The higher the water content of the working face, the more water needs to be discharged, and the more water guide holes need to be opened on it. Conversely, the lower the water content of the working face, the fewer water guide holes are needed.

[0034] According to a preferred embodiment of the present invention, in the excavation construction method for a stable tunnel face in water-rich strata, step S3, after the water guide holes on each sub-face have discharged water for a period of time, further includes the following operation:

[0035] The soil strength equipment is used to test the strength of the soil layer at a certain distance in front of each working face. Based on the different strengths of the soil layer in front of each working face, the amount of grouting material required per cubic meter of soil layer to achieve the same strength is calculated. The corresponding amount of grouting material is then injected into each working face according to the calculated amount. After the grouting material has completely hardened, the subsequent step S4 is carried out.

[0036] Considering that the strength of different face sections will change after drainage, if the conventional method of injecting grouting concrete into all face sections is adopted, the above implementation plan uses soil strength equipment to test the strength of the soil layer at a certain distance in front of each face section. Based on the different strengths of the soil layer in front of each face section, the amount of grouting material required per cubic meter of soil layer to achieve the same strength is calculated. In this way, grouting treatment can be carried out on the soil layer in front of different face sections in a targeted manner, so that the strength of all face sections is relatively consistent, avoiding subsequent problems caused by long-term inconsistency.

[0037] According to a preferred embodiment of the present invention, in the excavation construction method for a stable tunnel face in a water-rich stratum, in step S3, after the grouting material is injected, when the grouting material hardens to a preset hardness, the soil strength of the soil layer at a certain distance in front of each sub-face is tested again using a soil strength device. If the strength of one sub-face is less than the average value of the strength of all sub-faces within a certain range, grouting material is injected into that sub-face. When the grouting material of that sub-face hardens to a preset hardness, the soil strength device is tested again, and the strength is compared with the strength of other sub-faces when the grouting material is at the preset hardness. The above operation is repeated until the strength of each low-strength area is within the average value range.

[0038] The preset hardness is less than the hardness of the grouting material when it is fully hardened.

[0039] After the grouting material is injected, the strength of the grouted soil is tested according to the above implementation plan. If the strength does not meet the standard, corresponding measures are taken to ensure that the strength is consistent in the future.

[0040] According to a preferred embodiment of the present invention, in the excavation construction method for a stable tunnel face in water-rich strata, during the excavation process, support devices can be installed on adjacent sub-faces of the sub-face being excavated to further improve the overall stability.

[0041] According to a preferred embodiment of the present invention, in the excavation construction method for stabilizing the tunnel face in water-rich strata, grouting material is injected into the coating in front of the tunnel face using grouting anchor rods, and during the grouting process, fixed anchor rods are used to anchor into the soil layer for fixation, which can further improve the overall stability.

[0042] According to a preferred embodiment of the present invention, in the excavation construction method for a stable tunnel face in a water-rich stratum, multiple grouting holes are opened on the front end and side wall of the fixed anchor rod. Compared with the conventional fixed anchor rod which only has one grouting hole at the front end, the fixed anchor rod of the present application has multiple grouting holes on the front end and side wall, which can greatly improve the grouting efficiency and achieve uniform grouting.

[0043] According to a preferred embodiment of the present invention, in the excavation construction method for a stable tunnel face in water-rich strata, the concrete is high-strength concrete.

[0044] High-strength concrete refers to concrete with a strength grade of C60 and above, while concrete with a strength grade of C100 and above is called ultra-high-strength concrete. It is produced using conventional processes with cement, sand, and stone raw materials, plus water-reducing agents or simultaneously adding fly ash, mineral powder, slag, silica fume, etc.

[0045] According to a preferred embodiment of the present invention, in the excavation construction method for a stable tunnel face in a water-rich stratum, in step S3, after the grouting material has completely hardened, a thin layer of concrete is sprayed on the top of the tunnel face. After the thin layer of concrete hardens, it can be excavated and crushed, and it can also play a certain supporting role, but its strength can be easily crushed by the excavation equipment.

[0046] According to a preferred embodiment of the present invention, in the excavation construction method for a stable tunnel face in a water-rich stratum, in step S3, the grouting holes of the grouting anchors are all covered by sealing plates. The sealing plates are made of flexible material, and the shape and size of the sealing plates and the grouting holes are matched, both being circular. The sealing plates are divided into multiple triangular plates by multiple central axes. The triangular plates are acute triangles with two adjacent straight sides and one adjacent arc side, and the arc-shaped adjacent sides of the triangular plates together form a circle.

[0047] In the above implementation scheme, the purpose of setting the sealing plate is to prevent the grouting hole from being blocked by rocks or soil, which would prevent subsequent normal grouting. When grouting is not required, the flexible sealing plate can provide a temporary sealing effect. When grouting is needed, the grouting force can break open the triangular plate in the triangular plate of the flexible sealing plate to form a grouting channel.

[0048] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. An excavation construction method of stabilizing a tunnel face in a water- rich stratum, characterized by, The method comprises the following steps: Step S1, detecting the water content and rock stratum in front of the tunnel face, and dividing the tunnel face into multiple sub-faces according to the water content, and marking each sub-face; Step S2, determining the number of water guide holes to be drilled in each sub-face according to the water content and rock stratum of each sub-face, drilling a predetermined number of water guide holes in each sub-face using a drilling device, and draining water using the water guide holes, wherein the water guide holes are inclined from top to bottom; Step S3, waiting for a period of time after the water guide holes in each sub-face are discharged; Step S4, using a digging device to dig the tunnel, and dividing the length direction of the pre-dug tunnel into multiple sub-tunnel sections, and sequentially digging the multiple sub-tunnel sections, and for each sub-tunnel section, maintaining the order of digging from the two side sub-faces to the middle sub-face, and after digging each sub-face, coating a layer of concrete on the top surface of the sub-face; Step S5, repeating steps S2-S4 until the entire tunnel is excavated; In step S3, after a period of time after the water guide holes in each sub-face are discharged, the following operations are further included: Using a soil strength device to detect the strength of the soil layer at a certain distance in front of each sub-face, calculating the amount of grouting material needed per cubic meter of soil layer to reach the same strength according to the strength of the soil layer in front of each sub-face, and injecting the corresponding amount of grouting material into each sub-face according to the calculated amount, and after the grouting material is completely hardened, proceeding to the subsequent step S4; In step S3, after the grouting material is injected, when the grouting material hardens to a predetermined hardness, the soil strength device is used again to detect the strength of the soil layer at a certain distance in front of each sub-face, and if the strength of one of the sub-faces is less than the average strength of all sub-faces within a certain range, continue to inject grouting material into that sub-face, and when the grouting material in that sub-face hardens to a predetermined hardness, continue to use the soil strength device to detect and compare the strength of that sub-face with the strength of the other sub-faces at the predetermined hardness of the grouting material, and repeat the above operations until the strength of each low-strength area is within the average range; The predetermined hardness is less than the hardness when the grouting material is completely hardened; In step S3, after the grouting material is completely hardened, a thin layer of concrete is sprayed on the top of the sub-face, which can be hardened to crush the excavated material; In step S3, a grouting anchor is used to inject grouting material into the coating in front of the sub-face, and during the grouting process, a fixed anchor is anchored into the soil layer for anchoring, the grouting holes of the grouting anchor are covered by a sealing plate made of flexible material, the sealing plate and the grouting holes are adapted in shape and size, and are both circular, and the sealing plate is divided into multiple triangular plates by multiple central axes.

2. The water-rich formation tunneling method of stabilizing a face according to claim 1, characterized by, The higher the water content of the sub-face, the more water guide holes are opened.

3. The water-rich formation tunneling method of stabilizing a face according to claim 1, characterized by, In the digging process, a supporting device can be provided on the adjacent sub-face of the sub-face being excavated.

4. The water-rich formation tunneling method of stabilizing a face according to claim 1, characterized by, The front end and the side wall of the fixed anchor are provided with multiple injection holes.

5. The water-rich formation tunneling method of stabilizing a face according to claim 4, characterized by, The concrete is high-strength concrete. The concrete is high-strength concrete.