Method for temperature control and pressure relief of tunnel rock mass to be excavated under high ground stress and high ground temperature

Abstract

The invention provides a method for temperature control and pressure relief of a to-be-excavated rock mass of a tunnel under high ground stress and high ground temperature, and belongs to the technical field of tunnel engineering and deep mining. A plurality of crack guide holes are formed in the inclined front of the to-be-excavated direction in the surrounding to-be-excavated rock mass with the excavated area of the tunnel as the center; forming a guide groove for each crack guide hole at the same depth; directional fracturing is conducted along all the guide grooves through air pressure fracturing, and a plurality of cracks are obtained; a grouting device is used for injecting a delayed coagulation heat insulation liquid material into all the cracks at the same depth, and a pressure-relief heat insulation protection layer is formed; and temperature control and pressure relief are carried out by utilizing the pressure-relief and heat-insulation protection layer. Deep ground stress release is achieved, the rockburst risk is reduced, multi-layer heat insulation step-by-step temperature reduction is achieved, the temperature is transmitted to a preset excavation area, and finally a constant-temperature low-pressure area is formed near the preset excavation area.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel engineering and deep mining, and in particular to a method for controlling temperature and releasing pressure on a rock mass to be excavated in a tunnel under high ground stress and high ground temperature. Background Art

[0002] In tunnel engineering and deep mining, we often encounter complex extreme environments with high geostress and high geotemperature, which pose many challenges to the construction of related projects. In related projects, directional blasting and hydraulic fracturing are usually used to release geostress, and the temperature of the working area is controlled by arranging thermal insulation layers, extreme reinforcement support and water mist spraying on the surface of the excavation area.

[0003] In the existing technology, the related means for ground stress release and high ground temperature are mostly applied to a single special engineering background. However, in actual engineering, multiple complex situations are usually superimposed. The superposition of related technologies has greatly compressed the working space and working time, significantly slowing down the progress of the project. In addition, the expected effects of releasing ground stress and controlling temperature are also greatly reduced. The processing procedures of related technologies are complicated, the workload is large, and many personnel are required, which reduces the excavation efficiency and increases the cost.

[0004] Therefore, there is an urgent need for a method for controlling the temperature and relieving 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 temperature and releasing pressure on 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 in traditional related technologies.

[0006] To this end, the present invention provides the following technical solutions:

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

[0008] Taking the tunnel excavated area as the center, several guide holes are set in the surrounding rock mass to be excavated diagonally forward of the excavation direction;

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

[0010] Directional fracturing is performed along all guide grooves by gas pressure fracturing to obtain a number of fractures;

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

[0012] Furthermore, the plurality of crack guide holes are arranged in a circular direction with the excavated area of ​​the tunnel as the center;

[0013] The extending directions of the plurality of crack guiding holes are at an acute angle to the excavation direction and extend away from the excavated area;

[0014] The cross-sectional range formed at the front ends of the plurality of fracture guide holes is larger than the cross-sectional range of the rock mass to be excavated.

[0015] Furthermore, the angle range of the acute angle is determined by the depth of the guide hole, the ground stress and ground temperature of the surrounding rock, and the single excavation step.

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

[0017] Furthermore, the method of injecting slow-setting heat-insulating liquid material into all cracks at the same depth using a grouting device comprises:

[0018] The grouting device is provided with a sensor, and the grouting speed is adjusted and when to stop grouting is determined through a control system according to the monitoring data of the sensor;

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

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

[0021] Furthermore, the grouting sequence is from farthest from the excavated area to near the excavated area.

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

[0023] In the engineering context of high geotemperature and high geostress, deep geostress release is achieved through layered gas pressure fracturing in the advance area, thereby reducing the risk of rock burst. Multi-layer insulation is achieved by layered injection of slow-setting insulating liquid materials in the advance area, and then the temperature is gradually reduced and transferred to the predetermined excavation area, eventually forming a constant temperature and low-pressure area near the predetermined excavation area. Pressure release and temperature control are achieved at the same time, simplifying the steps of temperature control and pressure release during tunnel excavation. The excavation space is increased, the excavation efficiency is improved, and the excavation cost is saved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0025] Figure 1 A flow chart of a method in an embodiment of the present invention;

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

[0027] Figure 3 It is a schematic plan view of a pressure-releasing and temperature-insulating protective layer in an embodiment of the present invention;

[0028] Figure 4 Schematic diagram of temperature stress zones formed in an embodiment of the present invention.

[0029] Among them: 1. Excavation area; 2. Guide hole; 3. Directional cracks; 4. Slow-setting thermal insulation liquid material; 5. Surrounding rock; 6. Pressure relief and thermal insulation protective layer; 7. Pressure relief and thermal insulation protective belt. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work 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 and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0032] The present invention provides a method for controlling temperature and relieving pressure on a rock mass to be excavated in a tunnel under high ground stress and high ground temperature. Cracks are set in the rock mass to be excavated in the tunnel to form an annular structure, and temperature control materials are injected into the cracks to construct a plurality of pressure-releasing and temperature-insulating protective layers. The temperature is controlled while the pressure is released, thereby simplifying the processing procedure, thereby improving the efficiency of pressure release and temperature control, and reducing costs.

[0033] Combination Figure 1 Method flow chart and Figure 2-4 Schematic diagram of the pressure-releasing and temperature-insulating protective layer, further illustrating the method of the present invention:

[0034] S1, with the tunnel excavated area 1 as the center, a number of guide holes 2 are set in the surrounding rock mass to be excavated diagonally forward of the excavation direction;

[0035] S2, opening a guide groove for each guide hole at the same depth;

[0036] In this embodiment, with a deep rock excavation area 1 such as a tunnel or laneway as the center, a number of guide holes 2 are set in the rock body in four directions of the upper, lower, left and right directions in the diagonal front 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] The approximate stabilization time of the crack-guiding holes with the same aperture is calculated based on the ground stress and ground temperature of the surrounding rock. In this embodiment, when the crack-guiding hole depth is 10m, grouting takes 20 minutes, and the single excavation step is 2.5m. The approximate stabilization time of the crack-guiding holes in a certain area is 10 minutes, so the crack-guiding hole depth is selected as 5m. At this time, the crack-guiding hole angle is Therefore, the optional angle is 60°-90°.

[0038] S3, performing directional fracturing along all guide grooves by gas pressure fracturing to obtain a plurality of cracks;

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

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

[0041] In this embodiment, a slow-setting heat-insulating liquid material 4 is injected into the first crack by a grouting device; after the grouting is completed, the grouting pressure is maintained in a stable state and allowed to stand for a period of time to form a first pressure-releasing heat-insulating protective layer;

[0042] In this embodiment, the grouting device is provided with a temperature sensor, a humidity sensor and a pressure sensor, and the grouting speed is adjusted and when to stop the grouting is determined through the control system according to the sensor monitoring data;

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

[0044] In this embodiment, firstly, the surrounding rocks at different excavation stages are sampled separately 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 rocks to measure the relevant mechanical parameters of the surrounding rocks. At this time, the rock is subjected to systematic orthogonal tests on parameters such as proppant particle size grading, thermal insulation materials and overall proportioning scheme, and grouting verification is carried out separately. The thermal insulation properties, mechanical properties and grouting effects are comprehensively compared and analyzed to determine the proppant particle size grading, thermal insulation material selection and overall proportioning scheme of the slow-setting thermal insulation liquid material.

[0045] S5. In this embodiment, guide grooves parallel to the excavation direction are respectively set at the second and third predetermined depths of the crack guide hole 2, and steps S3 and S4 are repeated to form the second and third pressure-releasing and thermal-insulating protective layers 6, respectively, until the crack guide hole 2 and each pressure-releasing and thermal-insulating protective layer 6 are grouted.

[0046] In an environment of high ground stress and high ground temperature, the method of the present invention can control the temperature while releasing the pressure, thereby simplifying the processing procedure and forming a constant temperature and low pressure area near the area to be excavated, thereby 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, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements 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 controlling temperature and releasing pressure on rock mass to be excavated in a tunnel under high ground stress and high ground temperature, characterized in that: include: Taking the tunnel excavated area as the center, several guide holes are set in the surrounding rock mass to be excavated diagonally forward of the excavation direction; A guide groove is opened for each guide hole at the same depth; Directional fracturing is performed along all guide grooves by gas pressure fracturing to obtain a number of fractures; A slow-setting heat-insulating liquid material is injected into all cracks at the same depth by using a grouting device to form a pressure-relieving and heat-insulating protective layer; and the pressure-relieving and heat-insulating protective layer is used to control temperature and release pressure.

2. According to claim 1, a method for controlling temperature and releasing pressure on rock mass to be excavated in a tunnel under high ground stress and high ground temperature, characterized in that: The plurality of crack guide holes are arranged in a circular direction with the excavated area of ​​the tunnel as the center; The extending directions of the plurality of crack guiding holes are at an acute angle to the excavation direction and extend away from the excavated area; The cross-sectional range formed at the front ends of the plurality of fracture guide holes is larger than the cross-sectional range of the rock mass to be excavated.

3. A method for controlling temperature and releasing pressure on rock mass to be excavated in a tunnel under high ground stress and high ground temperature according to claim 2, characterized in that: The angle range of the acute angle is determined by the depth of the pilot hole, the ground stress of the surrounding rock, the ground temperature and the single excavation step.

4. The method for controlling temperature and releasing pressure on rock mass to be excavated in a tunnel under high ground stress and high ground temperature according to claim 1, characterized in that: The guide groove is parallel to the digging direction.

5. The method for controlling temperature and releasing pressure on rock mass to be excavated in a tunnel under high ground stress and high ground temperature according to claim 1, characterized in that: The method of injecting slow-setting heat-insulating liquid material into all cracks at the same depth by using a grouting device comprises: The grouting device is provided with a sensor, and the grouting speed is adjusted and when to stop grouting is determined through a control system according to the monitoring data of the sensor; The sensors include: a temperature sensor, a humidity sensor and a pressure sensor.

6. The method for controlling temperature and releasing pressure on rock mass to be excavated in a tunnel under high ground stress and high ground temperature according to claim 1, characterized in that: The number of the pressure-releasing and temperature-insulating protective layers is three or more.

7. The method for controlling temperature and releasing pressure on rock mass to be excavated in a tunnel under high ground stress and high ground temperature according to claim 5, characterized in that: The grouting sequence is from farthest from the excavated area to closer to the excavated area.

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