A method for controlling temperature and releasing pressure of tunnel rock mass to be excavated under high ground stress and high ground temperature

Abstract

This invention provides a method for controlling the temperature and releasing pressure in the rock mass to be excavated in a tunnel under high ground stress and high ground temperature, belonging to the fields of tunnel engineering and deep mining technology. Centered on the already excavated area of ​​the tunnel, several guide holes are set diagonally forward in the direction of excavation on the surrounding rock mass to be excavated. A guide groove is opened at the same depth for each guide hole. Directional fracturing is performed along all guide grooves using pneumatic fracturing to obtain several cracks. A slow-setting heat-insulating liquid material is injected into all cracks at the same depth using a grouting device to form a pressure-relieving and heat-insulating protective layer. Temperature and pressure are controlled and released using this pressure-relieving and heat-insulating protective layer. This achieves deep ground stress release, reduces the risk of rockburst, and achieves multi-layered heat insulation to gradually reduce temperature transmission to the predetermined excavation area, ultimately creating a constant temperature and low pressure zone near the predetermined excavation area.

Description

Technical Field

[0001] This invention relates to the fields of tunnel engineering and deep mining technology, and in particular to a method for controlling the temperature and releasing the pressure of the rock mass to be excavated in a tunnel under high ground stress and high ground temperature. Background Technology

[0002] In tunnel engineering and deep mining, situations involving multiple complex and extreme environments such as high ground stress and high ground temperature are frequently encountered, posing numerous challenges to the progress and construction of related projects. In these projects, directional blasting and hydraulic fracturing are typically used to release ground stress, while methods such as applying thermal insulation layers, extreme reinforcement supports, and water mist spraying to the surface of the excavation area are employed to control the temperature of the working area.

[0003] Existing technologies for stress release and high ground temperature are mostly applied to single, specific engineering scenarios. However, in actual engineering projects, multiple complex situations often overlap. The combined use of these technologies significantly reduces both the working space and time, noticeably slowing down the project progress. Furthermore, the expected effects of stress release and temperature control are greatly diminished. These technologies also involve complex processing procedures, a large workload, and high personnel requirements, leading to reduced excavation efficiency and increased costs.

[0004] Therefore, there is an urgent need for a method to control the temperature and release the pressure of the rock mass to be excavated in a tunnel under high ground stress and high ground temperature. Summary of the Invention

[0005] In view of this, the present invention provides a method for controlling the temperature and releasing pressure of the rock mass to be excavated in a tunnel under high ground stress and high ground temperature, which solves the problems of complicated processing procedures, low efficiency of temperature control and pressure release, and compressed working space of traditional related technologies.

[0006] Therefore, the present invention provides the following technical solution:

[0007] A method for controlling temperature and relieving pressure in the rock mass to be excavated in a tunnel under high ground stress and high ground temperature, comprising:

[0008] Centered on the already excavated area of ​​the tunnel, several guide holes are set diagonally forward in the direction of excavation on the surrounding rock mass to be excavated.

[0009] A guide groove is made at the same depth for each pilot hole;

[0010] Several cracks were obtained by directional fracturing along all guide grooves using pneumatic fracturing.

[0011] A slow-setting heat-insulating liquid material is injected into all cracks at the same depth using a grouting device to form a pressure-relieving and heat-insulating protective layer; the pressure-relieving and heat-insulating protective layer is used for temperature control and pressure relief.

[0012] Furthermore, the plurality of guide holes are arranged circumferentially around the excavated area of ​​the tunnel;

[0013] The direction of the plurality of guide holes extends at an acute angle to the excavation direction, moving away from the excavated area.

[0014] The front end of the aforementioned guide holes forms a cross-sectional area that is larger than the cross-sectional area of ​​the rock mass to be excavated.

[0015] Furthermore, the angle range of the acute angle is determined by the depth of the pilot hole, the geostress and geothermal temperature of the surrounding rock, and the single excavation step distance.

[0016] Furthermore, the guide groove is parallel to the excavation direction.

[0017] Furthermore, the method of injecting retarding insulating liquid material into all cracks at the same depth using a grouting device includes:

[0018] The grouting device is equipped with sensors, and the control system adjusts the grouting speed and determines when to stop grouting based on the sensor monitoring data.

[0019] The sensors include: a temperature sensor, a humidity sensor, and a pressure sensor.

[0020] Furthermore, the number of the pressure-relieving and heat-insulating protective layers is three or more.

[0021] Furthermore, the grouting sequence is from the area furthest from the excavated area to the area closest to the excavated area.

[0022] Advantages and positive effects of the present invention:

[0023] In high-temperature and high-stress engineering projects, deep stress release was achieved by stratified gas pressure fracturing in the advanced area, thereby reducing the risk of rockburst. Multi-layer insulation was achieved by injecting slow-setting heat-insulating liquid materials in the advanced area, thereby gradually reducing the temperature and transferring it to the predetermined excavation area, ultimately forming a constant-temperature and low-pressure area near the predetermined excavation area. This achieved both pressure release and temperature control, simplifying the steps of temperature control and pressure release during tunnel excavation. It also increased the excavation space, improved excavation efficiency, and saved excavation costs. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the 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 based on these drawings without creative effort.

[0025] Figure 1 This is a flowchart of the method in an embodiment of the present invention;

[0026] Figure 2 This is a schematic cross-sectional view of the pressure-relieving and heat-insulating protective layer in an embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of the pressure relief and thermal insulation protective layer in an embodiment of the present invention;

[0028] Figure 4 This is a schematic diagram of the temperature stress zoning formed in an embodiment of the present invention.

[0029] The components are: 1. Excavation area; 2. Guide hole; 3. Directional crack; 4. Slow-setting heat-insulating liquid material; 5. Surrounding rock; 6. Pressure-relieving heat-insulating protective layer; 7. Pressure-relieving heat-insulating protective strip. Detailed Implementation

[0030] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0031] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0032] This invention provides a method for controlling the temperature and releasing pressure of the rock mass to be excavated in a tunnel under high ground stress and high ground temperature. By setting cracks in the rock mass to be excavated to form a ring structure, and injecting temperature-controlling materials into the cracks to construct several pressure-releasing and temperature-insulating protective layers, temperature control is carried out at the same time as pressure release, simplifying the processing procedures, thereby improving the efficiency of pressure release and temperature control and reducing costs.

[0033] Combination Figure 1 Method flowchart and Figure 2-4 A schematic diagram of the pressure relief and thermal insulation protective layer further illustrates the method of the present invention:

[0034] S1. Taking the excavated area 1 of the tunnel as the center, set up a number of guide holes 2 on the surrounding rock mass to be excavated in the direction of excavation.

[0035] S2. Drill a guide groove at the same depth for each pilot hole;

[0036] In this embodiment, taking the deep rock excavation area 1 such as a tunnel or alley as the center, several guide holes 2 are set in the rock mass in four directions: up, down, left, and right, diagonally forward of the excavation direction; each guide hole 2 extends outward at a certain angle to the excavation direction; and a guide groove parallel to the excavation direction is set at the first predetermined depth of each guide hole 2.

[0037] Based on the calculation of the in-situ stress and geothermal temperature of the surrounding rock, the approximate stabilization time of the same diameter pilot hole is determined. In this embodiment, when the pilot hole depth is 10m, grouting requires 20 minutes, the single excavation step distance is 2.5m, and the approximate stabilization time of the pilot hole in a certain area is 10 minutes. Therefore, the pilot hole depth is selected as 5m, and the pilot hole angle is [missing value]. Therefore, the selectable angle is 60°-90°.

[0038] S3. Directional fracturing is performed along all guide grooves using pneumatic fracturing to obtain several cracks;

[0039] In this embodiment, pneumatic fracturing is selected to control the directional fracture 3 to be directionally fractured along the guide groove, so that the first directional fracture 3 reaches the set depth; the final pneumatic fracturing parameters are determined by multiple factors such as rock structure and lithology, thereby achieving precise control of the directional fracture 3.

[0040] S4. Use a grouting device to inject slow-setting heat-insulating liquid material into all cracks at the same depth to form a pressure-relieving and heat-insulating protective layer.

[0041] In this embodiment, a slow-setting heat-insulating liquid material 4 is injected into the first crack through a grouting device; after the grouting is completed, the grouting pressure is kept stable and left to stand for a period of time to form the first pressure-relieving heat-insulating protective layer.

[0042] In this embodiment, the grouting device is equipped with a temperature sensor, a humidity sensor, and a pressure sensor. Based on the sensor monitoring data, the control system adjusts the grouting speed and determines when to stop grouting.

[0043] The control system uses a Siemens S7400 controller and a programmable logic controller (PLC) as the master station to implement relevant control programs, thereby achieving real-time monitoring and automated adjustment of the grouting process.

[0044] In this embodiment, the surrounding rock at different excavation stages is first sampled and the ground stress level and ground temperature are measured. Then, based on the relevant parameters, confining pressure and temperature are applied to the surrounding rock, and the relevant mechanical parameters of the surrounding rock are measured. At this time, a systematic orthogonal test is conducted on the rock for parameters such as proppant particle size distribution, thermal insulation material and overall proportioning scheme, and grouting verification is performed separately. The thermal insulation performance, mechanical properties and grouting effect are comprehensively compared and analyzed to determine the proppant particle size distribution, thermal insulation material selection and overall proportioning scheme of the retarded thermal insulation liquid material.

[0045] S5. In this embodiment, guide grooves parallel to the excavation direction are set at the second and third predetermined depths of the guide hole 2. Steps S3 and S4 are repeated to form the second and third pressure relief and heat insulation protection layers 6 respectively, until the guide hole 2 and each pressure relief and heat insulation protection layer 6 are grouted.

[0046] In environments with high ground stress and high ground temperature, the method of this invention can control the temperature while releasing pressure, thereby simplifying the processing procedures and creating a constant temperature and low pressure zone near the area to be excavated, thus improving excavation efficiency and reducing costs.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for temperature control and pressure release of a tunnel to-be-excavated rock mass under high ground stress and high ground temperature, characterized in that, include: Centered on the already excavated area of ​​the tunnel, several guide holes are set diagonally forward in the direction of excavation on the surrounding rock mass to be excavated. The aforementioned guide holes are arranged in a circumferential manner with the excavated area of ​​the tunnel as the center; The direction of the plurality of guide holes extends at an acute angle to the excavation direction, moving away from the excavated area. The front end of the plurality of guide holes forms a cross-sectional area that is larger than the cross-sectional area of ​​the rock mass to be excavated. A guide groove is made at the same depth for each pilot hole; The guide groove is parallel to the excavation direction; Several cracks are obtained by directional fracturing along all guide grooves using pneumatic fracturing; a slow-setting heat-insulating liquid material is injected into all cracks at the same depth using a grouting device to form a pressure-relieving and heat-insulating protective layer; the pressure-relieving and heat-insulating protective layer is used for temperature control and pressure relief. The number of the pressure-relieving and heat-insulating protective layers is three or more; The acute angle range is determined by the depth of the pilot hole, the geostress and geothermal temperature of the surrounding rock, and the single excavation step distance.

2. The method for controlling temperature and releasing pressure in the rock mass to be excavated in a tunnel under high ground stress and high ground temperature as described in claim 1, characterized in that, The method of injecting retarded insulating liquid material into all cracks at the same depth using a grouting device includes: The grouting device is equipped with sensors, and the control system adjusts the grouting speed and determines when to stop grouting based on the sensor monitoring data. The sensors include: a temperature sensor, a humidity sensor, and a pressure sensor.

3. The method for controlling temperature and releasing pressure in the rock mass to be excavated in a tunnel under high ground stress and high ground temperature as described in claim 2, characterized in that, The grouting sequence is from the area furthest from the excavated area to the area closest to the excavated area.

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