Tunnel full-section excavation method in weak surrounding rock

Abstract

The invention provides a tunnel full-section excavation method in weak surrounding rock, which comprises the following steps: acquiring parameters of the surrounding rock, and judging whether the surrounding rock belongs to the weak surrounding rock or not; determining a tunnel excavation area; grouting holes are uniformly drilled in the area to be excavated, and surrounding rock grouting holes are drilled in the area to be excavated in a manner of being attached to the periphery of the area to be excavated; the surrounding rock grouting holes are subjected to full-length grouting, only the deepest positions in the holes are subjected to grouting through the grouting holes, and a grouting body surrounding the to-be-excavated area is formed through the peripheral enclosure structure and the deep enclosure structure; the construction face is covered with a sealing cover on the to-be-excavated face, and a stable first closed space is formed by the sealing cover and the grouting body; gas is inflated between the sealing cover and the grouting body, so that high pressure is formed in the first closed space; and in the first closed space, full-section excavation operation is conducted on the to-be-excavated area. The problems that under the existing weak surrounding rock condition, only a non-full-section partial excavation method can be adopted, procedures are complex, construction efficiency is low, and the period is long are solved. Belongs to the technical field of tunnel construction.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tunnel construction, in particular to a tunnel full-face excavation method in soft surrounding rock. BACKGROUND

[0002] Tunnel is an important engineering building buried in stratum, which is widely used in the fields of traffic, municipal administration, hydraulic engineering, etc. In the process of tunnel construction, the selection of excavation method is closely related to the stability of surrounding rock. Especially in soft surrounding rock stratum, due to the low strength, loose structure and large deformation capacity of surrounding rock, large convergence of surrounding rock and arch crown settlement are easily caused after excavation disturbance, and serious collapse, spalling and mud gushing may occur, which directly threatens the safety of construction personnel and causes delay in construction period.

[0003] In the condition of soft surrounding rock, in order to reduce the large deformation and instability risk of surrounding rock caused by excavation, non-full-face partial excavation methods such as bench method, CD method, CRD method and pilot tunnel method are usually used in engineering. Although this kind of method can improve the stability of surrounding rock by step excavation and timely closure, it also has obvious shortcomings:

[0004] 1) Many procedures and frequent conversion: partial excavation requires multiple block excavation, support and closure, and the construction organization is complex;

[0005] 2) Low construction efficiency and long cycle: small cycle footage, limited mechanization degree and difficult to improve tunneling efficiency;

[0006] 3) High cost: large investment in temporary support, long occupation time of machinery and labor, and significant increase in comprehensive cost;

[0007] 4) Limited cross-section utilization: partial construction needs to set up support, scaffold and formwork system many times, which occupies the excavation cross-section space and affects the slag discharge, transportation and subsequent lining operation;

[0008] 5) In extremely soft, water-rich or high-stress stratum, even if partial excavation is used, the problems of poor stability of surrounding rock, large support stress and high construction risk may still exist.

[0009] Therefore, how to realize full-face excavation in soft surrounding rock stratum and ensure that the surrounding rock obtains effective support during excavation, avoid large deformation and collapse, simplify the construction procedure, improve the tunneling speed and reduce the comprehensive cost has become a technical problem to be solved in the field. SUMMARY

[0010] The present application provides a tunnel full-face excavation method in soft surrounding rock, which solves the problems of complex procedure, low construction efficiency and long cycle in the prior art.

[0011] To solve the above technical problems, the application provides a tunnel full-face excavation method in soft surrounding rock, which comprises the following steps:

[0012] Step one, obtaining the parameters of surrounding rock to determine whether it belongs to soft surrounding rock;

[0013] Step two, determining the tunnel excavation area according to the tunnel design requirements to clarify the full-face excavation range;

[0014] Step three, surrounding rock drilling and grouting surrounding construction: drilling grouting holes uniformly distributed in the proposed excavation area, and drilling surrounding rock grouting holes along the outer periphery of the proposed excavation area, the depth of the grouting hole and the surrounding rock grouting hole is the same or close; the surrounding rock grouting hole is grouted throughout the length, the grout diffuses in the surrounding rock pores and connects with each other to form a continuous peripheral surrounding structure, the grouting hole only grouts a certain area at the deepest part of the hole, the grout diffuses in the pores and connects with each other to form a deep surrounding structure, after the grout solidifies, the peripheral surrounding structure and the deep surrounding structure form a grouting body surrounding the proposed excavation area;

[0015] The grouting body should have high density and low porosity to ensure that it has certain overall airtightness and bearing capacity.

[0016] Step four, covering the construction surface with a sealing cover on the proposed excavation surface, and making the sealing cover and the grouting body form a stable first airtight space;

[0017] Step five, filling gas between the sealing cover and the grouting body to form high pressure P1 in the first airtight space;

[0018] Step six, full-face excavation of the proposed excavation area in the first airtight space.

[0019] In the above method, before grouting the surrounding rock grouting hole, the sealing cover is covered on the proposed excavation area, and the outer periphery of the sealing cover is embedded in the surrounding rock to a certain depth. An annular embedding groove can be dug along the outer periphery of the surrounding rock grouting hole, the outer periphery of the sealing cover is embedded in the embedding groove, the embedding groove is backfilled, and then the surrounding rock grouting hole is grouted, so that the grouting body and the inner wall of the sealing cover form a surface contact, reliable lamination, further, the grouting body formed by pouring the surrounding rock grouting hole and the sealing cover are anchored and connected, the anchoring is distributed in the circumferential direction, or the bolt connection is fixed to ensure the overall sealing;

[0020] The method further comprises establishing a second closed space and performing pressure grading control: a second sealing cover is arranged at the outer end of the sealing cover, a second closed space is formed between the second sealing cover and the sealing cover, gas is filled into the first closed space to form a first high-pressure area, and the pressure value P1 is determined according to the stress analysis of the surrounding rock and is used as a standard to maintain the stability of the surrounding rock; gas is filled into the second closed space to form a second high-pressure area, and the pressure value P2 is less than P1; the pressure difference between the two closed spaces is set to reduce the pressure borne by the sealing cover structure and improve the safety of the system.

[0021] In the method, the sealing cover and the second sealing cover are an integral structure of metal / alloy material or a reinforced concrete structure formed by mold casting, the end of the sealing cover and the second sealing cover is provided with a sealable and closable sealing door meeting certain sealing performance requirements, and a high-pressure gas source is further provided, which supplies gas into the closed space through a closable gas supply port reserved on the sealing cover and the second sealing cover. A pressure sensor is further arranged in the closed space to monitor the gas pressure.

[0022] In the method, closed space inspection and pressure stabilization are further included: the sealing performance of the first closed space and the second closed space is inspected, if there is a trace of leakage, the stable pressure is maintained by continuously supplementing gas, after confirming that the pressure of the closed space is stable, the excavation construction phase is entered, and the gas pressure in the closed space is continuously monitored during excavation to ensure that the pressure value is constant.

[0023] In the method, the segmented full-face excavation construction includes: full-face excavation of the rock-soil body in the first closed space; the single excavation length is determined according to the construction design requirements to ensure the stability of the surrounding rock; during the excavation process, the high-pressure gas in the first closed space and the grouting body jointly provide support for the surrounding rock; if the conditions permit, remote control or unmanned equipment is used for excavation operation to improve safety, for example, a combination of an unmanned excavator and a remote-controlled slag removal vehicle is used for operation and construction outside the closed space through existing remote control technologies such as VR technology; during the entire excavation process, the pressure in the first closed space and the second closed space is kept constant.

[0024] In the method, closed transportation of earthwork is further included: when the excavated earthwork needs to be removed, the pressure P2 in the second closed space is first increased to the same value as the pressure P1 in the first closed space; the sealing cover is opened, the earthwork is transferred from the first closed space to the second closed space, the sealing cover is closed, the second sealing cover is opened, the earthwork is removed, the second sealing cover is closed, and the pressure in the second closed space is restored to the initial value P2; the safe transportation of the earthwork under high-pressure support is realized through the above method, and the opening and closing of the sealing cover refers to the opening and closing of the corresponding sealing door on the sealing cover.

[0025] In the above method, lining construction and parallel operation are further included: after completing single-section full-face excavation, steel bars or steel support are arranged in the section, and the lining is installed;

[0026] Further preferably, the lining is replaced by a lining formwork, which has a "U"-shaped cross-sectional structure, so that a third sealed space with a pouring port and an exhaust port is formed between the lining formwork and the grouting body; a gas or liquid is filled into the third sealed space to form a supporting pressure P3; the lining pouring is performed while keeping the pressure in the third sealed space constant; after the lining pouring is completed, the pouring port and the exhaust port are closed / sealed; while the lining construction is being performed, the excavation preparation or excavation operation of the next section of surrounding rock can be performed, so that the processes are parallel.

[0027] According to the above method, the construction is repeated, the tunnel full-face excavation is pushed forward section by section until the tunnel is through, the construction of the entire proposed excavation area is completed, and finally a tunnel structure with stable structure and complete lining is formed.

[0028] Compared with the existing non-full-face sectional excavation technology, the full-face excavation method and device of the present application have the following advantages:

[0029] 1) The full-face excavation under the condition of soft surrounding rock is realized, and the tunneling efficiency is significantly improved: the present application forms a gas-tight grouting body enclosure structure around the proposed excavation area, sets a sealing cover on the excavation face to form a sealed space, and fills high-pressure gas into the sealed space to provide support, so that the soft surrounding rock can still obtain stable support conditions during full-face excavation, thereby reducing the dependence on traditional sectional excavation method and improving the single-cycle footage and construction speed.

[0030] 2) "High-pressure gas + grouting body" collaborative support reduces the risk of surrounding rock deformation and collapse: the high-pressure gas forms a uniform surface force in the sealed space, and together with the grouting body, it forms a "air pressure-enclosure body" composite support system, which can continuously resist the inward convergence deformation of the surrounding rock during excavation, reduce the probability of arch crown settlement, peripheral displacement and local instability, and improve the safety of soft surrounding rock excavation.

[0031] 3) The construction procedure is simplified, the organization is clearer, and the process switching and site interference are reduced: compared with the step method and CRD sectional excavation which requires multiple excavation, support and closed loop, the present application takes "enclosing grouting-closing pressurizing-sectionally full-face excavation-lining" as the main line, the process is more intuitive, the process is less, the frequent process switching and temporary structure erection are reduced, and the construction organization efficiency is improved.

[0032] 4) Provide a "double-sealed space + two-stage pressure" transfer mechanism to take into account both slag removal and material entry and exit: By setting up a first sealed space and a second sealed space and controlling the pressure difference between P1 and P2, a "airlock"-like process for earthwork transfer and material transportation is achieved: When removing slag or feeding materials, the pressure of the second sealed space is first increased to be consistent with that of the first sealed space, and then the partition (sealing cover) is switched, thereby completing the entry and exit of earthwork and materials while maintaining high pressure support, reducing the impact on overall stability and improving continuous construction capability.

[0033] 5) The segment length can be determined by combining numerical analysis, and the construction plan can be quantified and controlled: Finite element analysis modeling is introduced before excavation to determine the length of the excavation segment and pressure parameters at one time, so that the construction design is transformed from experience-based to "analysis-parametric control", which improves the verifiability and adaptability of the plan and is conducive to its application under different soft surrounding rock grades, different stress and hydrological conditions.

[0034] 6) Lining construction can be carried out in parallel with tunneling, shortening the overall construction period: Under the protection of high pressure support and grouting body, the space occupied by lining formwork and temporary support can be reduced, and the preparation or excavation of the next section can be carried out in parallel while a section of lining is being poured, reducing waiting time and improving overall work efficiency.

[0035] 7) Reduce overall costs and support investment, and improve economic efficiency: Since it can reduce the number of temporary supports for sectional excavation, the time and material consumption of repeated formwork and support erection, and improve the efficiency of advance and shorten the construction period, it can effectively reduce labor, machine shifts, support materials and indirect management costs, resulting in a better overall cost. Attached Figure Description

[0036] Figure 1 This is a frontal view of the tunnel before excavation as described in this invention;

[0037] Figure 2 for Figure 1 AA cross-section diagram;

[0038] Figure 3 This is a frontal view of the tunnel before excavation after drilling grouting holes, as described in this invention.

[0039] Figure 4 for Figure 3 AA cross-section diagram;

[0040] Figure 5 This is a frontal view of the tunnel before and after grouting as described in this invention.

[0041] Figure 6 for Figure 5 AA cross-section diagram;

[0042] Figure 7 yes Figure 5Cross-sectional view of AA after adding the first and second sealing caps;

[0043] Figure 8 This is the AA section diagram after the first excavation;

[0044] Figure 9 This is the AA section diagram of the first transfer of earth and rock after the first excavation (the opening of the sealing cover 7 in the diagram is interpreted as the sealing door on the sealing cover 7 being opened).

[0045] Figure 10 This is a cross-sectional view of the tunnel described in this invention, showing the earth and rock being transferred for the first time after the first excavation and with the sealing cover closed.

[0046] Figure 11 It is a cross-sectional view of section AA with the earth and rock moved for the second time after the first excavation and with the second sealing cover open.

[0047] Figure 12 This is the AA section diagram after the lining was poured following the first excavation;

[0048] Figure 13 This is a frontal schematic diagram of the tunnel lining after the first excavation and pouring of the tunnel according to the present invention (the sealing cap structure is omitted).

[0049] Figure 14 This is a cross-sectional view of section AA after the excavation and lining pouring are completed;

[0050] Figure 15 This is a frontal schematic diagram of the completed lining formwork construction after the first excavation of the tunnel according to the present invention (the sealing cover structure is omitted).

[0051] Figure 16 yes Figure 15 AA cross-section diagram;

[0052] Figure 17 This is a frontal view of the completed lining formwork construction after the first excavation of the tunnel in Example 3 (the sealing cover structure is omitted).

[0053] Figure 18 yes Figure 17 AA cross-section diagram. Detailed Implementation

[0054] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0055] In the following description, certain specific details are set forth for the purpose of illustrating various disclosed embodiments in order to provide a thorough understanding of the various disclosed embodiments. However, those skilled in the art will recognize that embodiments may be practiced without one or more of these specific details. In other instances, well-known apparatuses, structures, and techniques associated with this application may not have been shown or described in detail to avoid unnecessarily obscuring the description of the embodiments.

[0056] Throughout this specification, references to "an embodiment" or "an embodiment" indicate that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Therefore, the appearance of "in an embodiment" or "an embodiment" in various places throughout the specification does not necessarily refer to the same embodiment. Furthermore, a particular feature, structure, or characteristic may be combined in any manner in one or more embodiments.

[0057] In the following description, in order to clearly demonstrate the structure and working method of the present invention, a number of directional terms will be used. However, terms such as "front", "back", "left", "right", "outside", "inside", "outward", "inward", "up", and "down" should be understood as convenient terms and not as limiting terms.

[0058] Example 1:

[0059] See attached document Figures 1 to 14 This embodiment provides a method for full-face tunnel excavation in weak surrounding rock. Through a construction process of "surrounding rock grouting and enclosure—sealing cap to form a closed space—high-pressure gas support—segmented full-face excavation—closed-loop transportation—parallel lining," it achieves safe and efficient full-face tunnel excavation under weak surrounding rock conditions. It is suitable for tunnel projects with low surrounding rock strength, poor stability, and where conventional full-face excavation is not suitable. The construction steps are as follows:

[0060] Step 1: Surrounding Rock Investigation and Engineering Assessment

[0061] Before tunnel construction, a detailed geological survey of the surrounding rock in the area to be excavated was conducted.

[0062] Rock samples are obtained through drilling, core sampling, and other methods to test the physical and mechanical parameters of the surrounding rock, such as strength, deformation modulus, porosity, and permeability.

[0063] The surrounding rock was classified and assessed to determine that it belonged to the type of weak surrounding rock;

[0064] The drilled rock and soil cores and test results will serve as the basis for subsequent grouting parameters, high-pressure support pressure, and numerical analysis.

[0065] Step 2: Determine the tunnel excavation area and cross-sectional shape: Based on the tunnel design requirements, determine the tunnel excavation area; mark the outline of the proposed excavation area and clarify the full cross-sectional excavation range.

[0066] Step 3: Drilling and Grouting Enclosure of Surrounding Rock: Drill grouting holes 3 evenly distributed in the area to be excavated 2, and drill surrounding rock grouting holes 4 along the outer perimeter of the area to be excavated 2. The depths of the grouting holes 3 and the surrounding rock grouting holes 4 are the same or close. Grouting is performed along the entire length of the surrounding rock grouting holes 4. The grout diffuses in the pores of the surrounding rock and connects with each other to form a continuous outer enclosure structure 5. Grouting is performed only in a certain area at the deepest point of the grouting holes 3 (for example, the deepest area is 10cm to 50cm in length, depending on the softness of the surrounding rock. If the softness is high, the pouring width is appropriately increased). The grout diffuses in the pores and connects with each other to form a deep enclosure structure 6. After the grout solidifies, the grouting body surrounding the area to be excavated 2 is formed by the outer enclosure structure 5 and the deep enclosure structure 6.

[0067] The grouting body should have high density and low porosity to ensure that it has a certain degree of overall airtightness and load-bearing capacity.

[0068] Step 4: Cover the construction surface with the sealing cap 7 on the proposed excavation surface, and make the sealing cap 7 and the grouting body form a stable first sealed space 8;

[0069] Before grouting the surrounding rock grouting hole 4, first place the sealing cover 7 over the area to be excavated 2, and embed the outer periphery of the sealing cover 7 into the surrounding rock to a certain depth. You can first dig an annular embedding groove around the surrounding rock grouting hole 4, and embed the outer periphery of the sealing cover 7 into the embedding groove. Then backfill the embedding groove, and then grout the surrounding rock grouting hole 4, so that the grout body and the inner wall of the sealing cover 7 form a surface contact and reliably fit. Furthermore, anchor the grout body formed by the surrounding rock grouting hole 4 and the sealing cover 7, and anchor it along the circumferential direction, or fix it with bolts to ensure overall sealing.

[0070] In this embodiment, the sealing cover 7 is an integral structure made of metal / alloy material, or a reinforced concrete structure cast by a template. The ends of the sealing cover 7 are provided with a sealing door that can be opened and closed to meet certain sealing performance requirements. It also includes a high-pressure air source, which supplies air to the enclosed space through a pre-reserved sealable air supply port on the sealing cover 7. A pressure sensor is also provided in the enclosed space to monitor the air pressure.

[0071] Step 5: Inject gas between the sealing cap 7 and the grouting body to create a high pressure P1 in the first sealed space 8.

[0072] Step 6: In the first enclosed space 8, carry out full-section excavation of the area to be excavated 2.

[0073] In another embodiment, the system further includes establishing a second sealed space 10 and implementing pressure grading control: a second sealing cover 9 is provided at the outer end of the sealing cover 7, forming a second sealed space 10 between the second sealing cover 9 and the sealing cover 7; gas is injected into the first sealed space 8 to form a first high-pressure zone, with the pressure value P1 determined based on the stress analysis of the surrounding rock, with the standard of maintaining the stability of the surrounding rock; gas is injected into the second sealed space 10 to form a second high-pressure zone, with the pressure value P2 being less than P1; by setting the pressure difference between the two sealed spaces, the pressure borne by the sealing cover structure is reduced, thereby improving system safety.

[0074] In another embodiment described above, the second sealing cover 9, like the sealing cover 7, is an integral structure made of metal / alloy material. The second sealing cover 9 and the sealing cover 7 are welded together to achieve a sealed fixation. Alternatively, the second sealing cover 9, like the sealing cover 7, is a reinforced concrete structure cast by a template. In this case, the two are connected by casting / masonry to form an integrated structure / sealed fixation, provided that the pressure resistance of the second sealing cover 9 and the sealing cover 7 can withstand the pressure in the corresponding sealed space. The end of the second sealing cover 9 is also provided with a sealing door that can be opened and closed to meet certain sealing performance requirements. It also includes a high-pressure air source, which supplies air to the sealed space through a pre-reserved sealable air supply port on the second sealing cover 9. A pressure sensor is also provided in the sealed space to monitor the air pressure.

[0075] Sealed space inspection and pressure stabilization: The sealing performance of the first sealed space 8 and the second sealed space 10 is inspected. If there is a slight leak, the pressure is maintained by continuously replenishing air. After confirming that the pressure of the sealed space is stable, the excavation construction stage begins. During the excavation process, the gas pressure in the sealed space is continuously monitored to ensure that the pressure value is constant.

[0076] Segmented full-section excavation construction: The rock and soil mass is excavated in full section within the first enclosed space 8; the length of each excavation is determined according to the construction design requirements to ensure the stability of the surrounding rock; during the excavation process, the high-pressure gas and grout in the first enclosed space 8 provide support for the surrounding rock; if conditions permit, remote control or unmanned equipment is used for excavation operations to improve safety; throughout the entire excavation process, the pressure in the first enclosed space 8 and the second enclosed space 10 is kept constant.

[0077] Sealed transfer of earth and rock: When it is necessary to remove the excavated earth and rock 13, firstly, the pressure P2 in the second sealed space 10 is increased to the same as the pressure P1 in the first sealed space 8; the sealing cover 7 is opened, and the earth and rock 13 is transferred from the first sealed space 8 to the second sealed space 10; the sealing cover 7 is closed; the second sealing cover 9 is opened, and the earth and rock 13 is removed; the second sealing cover 9 is closed, and the pressure in the second sealed space 10 is restored to the initial value P2; the safe transfer of earth and rock 13 under high pressure support is achieved through the above method. The opening and closing of the sealing cover refers to opening and closing the corresponding sealing door on the sealing cover.

[0078] Lining construction and parallel operations: After completing the full-section excavation of a single section, steel bars or steel supports are arranged in the section; lining 11 is installed, and after the lining is poured, the grouting port and vent are closed / sealed; while the lining is being constructed, preparation for or excavation of the next section of surrounding rock can be carried out, so as to achieve parallel operation of the process.

[0079] Following the above method, the construction is repeated, and the tunnel is excavated section by section until the tunnel is completed, thus completing the construction of the entire planned excavation area and finally forming a stable and fully lined tunnel structure.

[0080] Example 2:

[0081] like Figure 15 and Figure 16 The difference between this embodiment and embodiment 1 is that: the lining template 12 is used instead of the lining 11. The lining template 12 has a "U" shaped cross-section structure, so that a third sealed space 14 with an injection port and an exhaust port is formed between the lining template 12 and the grouting body; gas or liquid is filled into the third sealed space 14 to form a supporting pressure P3; the lining is poured while maintaining a constant pressure in the third sealed space 14. To ensure the sealing of the third sealed space 14, a film (plastic or rubber) of a certain thickness can be attached to the inner wall of the third sealed space 14.

[0082] Example 3:

[0083] like Figure 17 and Figure 18 The difference between this embodiment and embodiment 1 is that the surrounding rock in this embodiment is a non-weak rock layer. After the excavation is completed, gas or liquid is filled into the third sealed space 14. At this time, the high-pressure fluid in the third sealed space 14 and the lining template 12 together serve as a temporary support structure. The lining template 12 is also a "U" shaped cross-section structure. When installed, it is tightly attached to the grouting body. This support scheme can be used for temporary support in tunnels or mines (roadways). During the support process, the pressure in the first sealed space 8 and the third sealed space 14 can be adjusted according to the construction needs. In order to ensure the sealing of the third sealed space 14, a film (plastic or rubber) of a certain thickness can be attached to the inner wall of the third sealed space 14.

[0084] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for full-section excavation of tunnels in weak surrounding rock, characterized in that, include: Step 1: Obtain the parameters of the surrounding rock (1) and determine whether it is a weak surrounding rock; Step 2: Determine the tunnel excavation area and clarify the full-section excavation range according to the tunnel design requirements; Step 3, Drilling and Grouting Enclosure Construction of Surrounding Rock: Drill grouting holes (3) evenly distributed in the area to be excavated (2), and drill surrounding rock grouting holes (4) close to the outer perimeter of the area to be excavated (2). The depth of the grouting holes (3) and the surrounding rock grouting holes (4) is the same or close. Grouting is performed along the entire length of the surrounding rock grouting holes (4). The grout diffuses in the pores of the surrounding rock and connects with each other to form a continuous outer enclosure structure (5). Grouting is performed in a certain area at the deepest point of the grouting hole (3). The grout diffuses in the pores and connects with each other to form a deep enclosure structure (6). After the grout solidifies, the grouting body surrounding the area to be excavated (2) is formed by the outer enclosure structure (5) and the deep enclosure structure (6). Step 4: Cover the construction surface with a sealing cap (7) on the planned excavation surface, and make the sealing cap (7) and the grouting body form a stable first sealed space (8); Step 5: Inject gas between the sealing cap (7) and the grouting body to create a high pressure P1 in the first sealed space (8); Step 6: In the first enclosed space (8), carry out full-section excavation of the area (2) to be excavated.

2. The full-section excavation method according to claim 1, characterized in that: Before grouting the surrounding rock grouting hole (4), first cover the area to be excavated (2) with the sealing cover (7) and embed the outer periphery of the sealing cover (7) into the surrounding rock to a certain depth. Then anchor the grouting body formed by the surrounding rock grouting hole (4) and the sealing cover (7) or fix it with bolts.

3. The full-section excavation method according to claim 1, characterized in that, It also includes establishing a second sealed space (10) and performing pressure grading control: a second sealing cover (9) is set at the outer end of the sealing cover (7), and a second sealed space (10) is formed between the second sealing cover (9) and the sealing cover (7). Gas is filled into the first sealed space (8) to form a first high-pressure zone. The pressure value P1 is determined according to the stress analysis of the surrounding rock, with the standard of maintaining the stability of the surrounding rock. Gas is filled into the second sealed space (10) to form a second high-pressure zone. The pressure value P2 is less than P1.

4. The full-section excavation method according to claim 3, characterized in that: The sealing cover (7) and the second sealing cover (9) are integral structures made of metal / alloy materials, or reinforced concrete structures cast by template. The ends of the sealing cover (7) and the second sealing cover (9) are provided with sealing doors that can be opened and closed to meet certain sealing performance requirements. They also include a high-pressure air source. The high-pressure air source also supplies air to the enclosed space through the air supply ports reserved on the sealing cover (7) and the second sealing cover (9). A pressure sensor is also installed in the enclosed space to monitor the air pressure.

5. The full-section excavation method according to claim 3, characterized in that: It also includes closed space inspection and pressure stabilization: the sealing performance of the first closed space (8) and the second closed space (10) is inspected. If there is a slight leak, the pressure is maintained by continuous gas replenishment. After confirming that the pressure of the closed space is stable, the excavation construction stage is entered. During the excavation process, the gas pressure in the closed space is continuously monitored to ensure that the pressure value is constant.

6. The full-section excavation method according to claim 3, characterized in that, The segmented full-section excavation construction includes: full-section excavation of the rock and soil in the first enclosed space (8); the single excavation length is determined according to the construction design requirements to ensure the stability of the surrounding rock; during the excavation process, the high-pressure gas in the first enclosed space (8) and the grouting body together provide support for the surrounding rock; the excavation operation is carried out using remote control or unmanned equipment; and the pressure in the first enclosed space (8) and the second enclosed space (10) is kept constant throughout the entire excavation process.

7. The full-section excavation method according to claim 6, characterized in that, It also includes the closed transfer of earth and stone: when it is necessary to remove the excavated earth and stone, firstly, the pressure P2 in the second closed space (10) is increased to the same as the pressure P1 in the first closed space (8); open the sealing cover (7) and transfer the earth and stone from the first closed space (8) to the second closed space (10); close the sealing cover (7); open the second sealing cover (9) and remove the earth and stone; close the second sealing cover (9) and restore the pressure in the second closed space (10) to the initial value P2; the safe transfer of earth and stone under high pressure support is achieved by the above method. The opening and closing of the sealing cover refers to opening and closing the corresponding sealing door on the sealing cover.

8. The full-section excavation method according to claim 7, characterized in that, It also includes lining construction and parallel operations: after completing the full-section excavation of a single section, steel bars or steel supports are arranged in the section and the lining is installed (11).

9. The full-section excavation method according to claim 8, characterized in that: The lining (11) is replaced by a lining template (12), which has a "U" shaped cross-section structure, so that a third sealed space (14) with an injection port and an exhaust port is formed between the lining template (12) and the grouting body; gas or liquid is injected into the third sealed space (14) to form a supporting pressure P3; the lining is poured while the pressure in the third sealed space (14) is kept constant; after the lining is poured, the injection port and exhaust port are closed / sealed; while the lining is being constructed, the excavation preparation or excavation operation of the next section of surrounding rock can be carried out to achieve parallel operation of the process.

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