Deep-buried tunnel whole life period external water pressure evolution process monitoring system and method

Abstract

The application discloses a deep-buried tunnel whole life period external water pressure evolution process monitoring system and method. The monitoring system comprises a surface deep hole advanced layered water pressure monitoring unit and a tunnel multi-hole water pressure monitoring unit, and realizes real-time monitoring of the whole life period external water pressure of the deep-buried tunnel by automatically collecting and transmitting data through a multi-channel data acquisition instrument and a wireless transmission module. The monitoring method is as follows: according to the heading stake number and the stratum lithology characteristics of the deep-buried tunnel, the stake number of the field monitoring section is determined; the surface deep hole advanced layered water pressure monitoring unit is arranged above the monitoring section, and monitoring is performed; the tunnel multi-hole water pressure monitoring unit is arranged on the monitoring section, and monitoring is performed. Compared with the prior art, the application can realize real-time monitoring of the formation and evolution process of the whole life period external water pressure of the deep-buried tunnel, and fills the gap in the prior art.

Description

Technical Field

[0001] This invention relates to a system and method for monitoring external water pressure in deeply buried tunnels. Specifically, it relates to a system and method for real-time monitoring of the formation and evolution of external water pressure throughout the entire lifespan of deeply buried tunnels. This invention can be applied to the real-time monitoring and analysis of the formation and evolution of external water pressure throughout the entire lifespan of long-distance deeply buried tunnels in the field of water conservancy and hydropower engineering, from the start of construction to the entire construction process, completion of construction, and operation, providing a scientific basis for the design of deeply buried tunnels. Background Technology

[0002] In recent years, with the construction of long-distance water diversion projects in my country, deep-buried tunnels have been increasingly common. Most of these tunnels have a maximum burial depth of 500m to 1000m below the surface. However, some individual projects now have tunnels with a maximum burial depth exceeding 2000m, such as the Hanjiang-to-Weihe River Water Diversion Project tunnel (2012m below the surface) and the Jinping II Hydropower Station water diversion tunnel (2525m below the surface). Due to the great depth of these deep-buried tunnels, the design of these projects generally faces the problem of high external water pressure. Therefore, external water pressure is an important factor that must be considered in the design of deep-buried tunnels in long-distance water diversion projects.

[0003] According to the current "Design Code for Hydraulic Tunnels" (SL279-2016), the external pressure acting on the tunnel lining structure can be estimated by multiplying the initial water head above the tunnel by a reduction factor. Therefore, when designing deep-buried tunnels, it is necessary to determine the initial water head above the tunnel before excavation. Because deep-buried tunnels differ from shallow-buried tunnels in their greater depth, multiple strata with varying permeability are generally distributed above them, and there may also be one or more impermeable layers in some areas, causing a loss of hydraulic connection between the upper and lower strata. Therefore, only by monitoring the hydraulic connection between different strata layer by layer can the initial water head above the tunnel before excavation be accurately obtained.

[0004] However, currently, the initial water head above a deeply buried tunnel before excavation is mainly determined in engineering projects through surface borehole monitoring. This involves drilling a borehole in the surface strata and installing only one monitoring instrument inside the borehole. The drawback of this monitoring method is that it only monitors the initial water head of the surface strata above or below the surface of the deeply buried tunnel before excavation. The measured results do not accurately reflect the initial water head above the tunnel before excavation. Therefore, the estimated external water pressure on the deeply buried tunnel based on this is inaccurate, and the designed lining structure of the deeply buried tunnel is also inaccurate.

[0005] In addition, the external water pressure acting on the lining structure of deeply buried tunnels is not only related to the initial water head above the tunnel, but also affected by the seepage control measures taken to cope with high external water pressure (such as surrounding rock grouting and lining drainage). Different seepage control measures will result in different external water pressures acting on deeply buried tunnels, which will in turn affect the final value of the reduction factor in the "Design Code for Hydraulic Tunnels" (SL279-2016).

[0006] In summary, there is currently a lack of scientific and accurate methods for monitoring external water pressure in the design and on-site construction of deep-buried tunnels. Summary of the Invention

[0007] In view of the above reasons, the purpose of this invention is to provide a monitoring system and method for external water pressure in deeply buried tunnels throughout their entire life cycle. This monitoring system and method can realize real-time monitoring of the formation process and evolution of external water pressure in tunnels throughout their entire life cycle, from the start of construction to completion and operation, providing a scientific basis for the design of deeply buried tunnels.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: a method for monitoring the evolution of external water pressure throughout the entire life cycle of a deeply buried tunnel, comprising the following steps:

[0009] S1. Determine the station number of the on-site monitoring section based on the station number of the tunnel face and the lithological characteristics of the strata.

[0010] S1.1. Using the source-sink theory model, determine the total water head φ around the tunnel face of the deep-buried tunnel;

[0011] S1.2 Monitor the water inflow Q at the tunnel face during the construction of the deep-buried tunnel, and determine the radius of influence r of the groundwater at the tunnel face based on the total water head φ around the tunnel face. d ;

[0012]

[0013] Where: Q is the water inflow at the tunnel face; k is the maximum permeability coefficient of the overlying strata of the deep tunnel; β is the total water head percentage coefficient; h0 is the vertical depth from the groundwater level to the tunnel axis.

[0014] S1.3, Based on the station number of the tunnel face and the radius of influence of groundwater r d Determine the station number K of the on-site monitoring section ahead of the tunnel face:

[0015] K-K0=αr d

[0016] In the formula: K0 is the station number of the excavation face of the deep-buried tunnel, r dThe radius of influence of groundwater at the excavation face of a deep-buried tunnel; α is the safety factor, generally taken as α = 1.5;

[0017] S.2: Directly above the on-site monitoring section, deploy surface deep borehole advanced stratified water pressure monitoring units to monitor the external water pressure of the deep buried tunnel throughout its entire life cycle;

[0018] S2.1. Drill a deep borehole directly above the monitoring section, starting from the surface strata and drilling downwards.

[0019] The aperture is not less than 76mm; the depth h of the hole is:

[0020] h = H0 - rTD

[0021] In the formula, T is the thickness of the consolidation grouting layer of the deep-buried tunnel, in meters; r is the radius of the deep-buried tunnel, in meters; H0 is the burial depth of the deep-buried tunnel, in meters; and D is the distance from the bottom of the deep borehole on the ground surface to the outer ring of the consolidation grouting layer of the deep-buried tunnel.

[0022] S2.2. In the deep borehole at the surface, at least one piezometer is installed in each stratum section from the bottom of the borehole upwards; a sealing section is injected at the boundary between two adjacent strata to physically isolate the two adjacent piezometers.

[0023] S2.3. Deploy a multi-channel data acquisition instrument and a wireless data transmission unit on the ground surface; the measurement data output terminal of each piezometer is connected to the signal input terminal of the multi-channel data acquisition instrument through a signal cable; the multi-channel data acquisition instrument stores the received data in a server or cloud platform through the wireless data transmission unit for retrieval and analysis by the control terminal or host computer.

[0024] S2.4 Utilize piezometers in deep boreholes at the surface to monitor external water pressure throughout the entire life cycle of deeply buried tunnels;

[0025] S.3: When the deep-buried tunnel is excavated to the monitoring section, a multi-hole water pressure monitoring unit is installed in the tunnel to monitor the water pressure during the excavation process and operation period of the deep-buried tunnel.

[0026] S3.1 At the monitoring section of the deep-buried tunnel, at least three monitoring holes with radial depths greater than 76 mm shall be drilled from the inside of the tunnel outwards; one monitoring hole shall be located in the outer rock layer of the tunnel consolidation grouting layer to monitor the average water pressure in the outer rock layer; one monitoring hole shall be located in the tunnel consolidation grouting layer to monitor the average water pressure in the consolidation grouting layer; and one monitoring hole shall be located outside the lining layer of the deep-buried tunnel to monitor the water pressure applied to the outside of the lining layer of the deep-buried tunnel.

[0027] Each monitoring hole inside the tunnel is divided into two parts: the front section, which is farther away from the deep-buried tunnel, is the measurement section; the rear section, which is closer to the deep-buried tunnel, is the sealing section.

[0028] S3.2. Install a piezometer in the measuring section of each monitoring hole in the tunnel, and fill the entire measuring section with fine sand, with the piezometer encased in the fine sand;

[0029] S3.3. A multi-channel data acquisition instrument and a wireless data transmission unit are installed inside the tunnel; the measurement data output terminal of each piezometer is connected to the signal input terminal of the multi-channel data acquisition instrument via a signal cable; the multi-channel data acquisition instrument stores the received data in a server or cloud platform via the wireless data transmission unit for retrieval and analysis by the control terminal or host computer.

[0030] S3.4. Seal the rear section of each monitoring hole in the tunnel with grout to prevent hole leakage;

[0031] S3.5. Use the piezometer in the monitoring hole inside the tunnel to monitor the water pressure outside the deep-buried tunnel;

[0032] S3.6. The lining is constructed in sequence, grouting is carried out, and water is filled for operation. The water pressure outside the deep-buried tunnel is monitored in real time using the multi-hole water pressure monitoring unit inside the tunnel.

[0033] Furthermore, the on-site monitoring section selected in step S1 is located in the same hydrogeological unit as the tunnel face.

[0034] Furthermore, the deployment of the surface deep borehole advanced stratified water pressure monitoring unit in step S2 must be carried out at the tunnel face to a distance r from the surface deep borehole. d The scope was completed beforehand.

[0035] Furthermore, in step S2.2, the length of the sealing section injected at the boundary between two adjacent strata is greater than 2m.

[0036] Furthermore, in step S3.1, the depths of the three in-tunnel monitoring holes, from shallow to deep, reach the outer side of the deep-buried tunnel lining layer, the middle position of the pre-consolidated grouting layer, and the outer rock layer, respectively; and the length of the sealing section of the in-tunnel monitoring hole located in the outer rock layer is greater than the hole depth of the in-tunnel monitoring hole located in the consolidation grouting layer; the length of the sealing section of the in-tunnel monitoring hole located in the consolidation grouting layer is greater than the hole depth of the in-tunnel monitoring hole located on the outer side of the deep-buried tunnel lining layer.

[0037] Furthermore, the relationship between the radial depths of the three monitoring holes in step S3.1 is as follows:

[0038]

[0039] In the formula, d 11 d 21 d 31 These represent the lengths of the monitoring borehole measurement sections within the three boreholes, from smallest to largest depth, in meters (m) and d, respectively.12 d 22 d 32 The numbers represent the lengths of the sealing sections of the monitoring holes in the three tunnels, from smallest to largest depth, in meters. T represents the thickness of the consolidation grouting layer around the deep-buried tunnel, in meters.

[0040] Furthermore, the length d of the monitoring hole measuring section located in the rock strata surrounding the consolidation grouting layer of the deep-buried tunnel is... 31 The length d of the measuring section of the monitoring hole located within the consolidation grouting layer of the deep-buried tunnel is greater than or equal to 2.0m. 21 Greater than 1.0m; the length d of the monitoring hole measuring section located outside the lining layer of the deep-buried tunnel. 11 Greater than 0.5m.

[0041] This invention discloses a deep-buried tunnel full-life-cycle external water pressure monitoring system, which includes a surface deep-hole advanced stratified water pressure monitoring unit, an in-tunnel multi-hole water pressure monitoring unit, and a data wireless transmission unit.

[0042] The surface deep borehole advanced stratified water pressure monitoring unit includes a surface deep borehole, several piezometers, and a multi-channel data acquisition instrument.

[0043] The surface deep borehole is located in front of the excavation face of the deep-buried tunnel and above the completed deep-buried tunnel; the surface deep borehole is drilled from the surface to above the deep-buried tunnel, passing through different strata of the mountain; at least one piezometer is installed in each stratum section of the surface deep borehole; the measurement data output terminal of each piezometer is connected to the signal input terminal of the multi-channel data acquisition instrument via a signal cable; a sealing section is injected at the stratum boundary line in the surface deep borehole;

[0044] The in-tunnel multi-hole water pressure monitoring unit is located directly below the surface deep hole and on the monitoring section perpendicular to the tunnel axis; the in-tunnel multi-hole water pressure monitoring unit includes at least three in-tunnel monitoring holes, at least three piezometers, and a multi-channel data acquisition instrument;

[0045] All the monitoring holes inside the tunnel are located on the same cross section, and the radial depth of each monitoring hole inside the tunnel is different; at least one monitoring hole inside the tunnel is located in the rock strata surrounding the deep-buried tunnel, one monitoring hole inside the tunnel is located in the consolidation grouting layer of the deep-buried tunnel, and one monitoring hole inside the tunnel is located outside the lining layer of the deep-buried tunnel.

[0046] A piezometer is placed in the monitoring hole of each tunnel; a multi-channel data acquisition instrument and a wireless transmission module are installed in the deep-buried tunnel; the measurement data output terminal of each piezometer is connected to the signal input terminal of the multi-channel data acquisition instrument via a signal cable;

[0047] The multi-channel data acquisition instrument stores the received data in a server or cloud platform through the wireless data transmission unit, which can then be retrieved by the control terminal or host computer.

[0048] Furthermore, the relationship between the station number K of the deep surface borehole and the station number K0 of the excavation face of the deep-buried tunnel is as follows:

[0049] K-K0=αr d

[0050] Where: K0 is the station number of the excavation face of the deep-buried tunnel, r d The radius of influence of groundwater at the excavation face of a deep-buried tunnel; α is the safety factor;

[0051] The depth h of the surface borehole is:

[0052] h = H0 - rTD

[0053] In the formula, T is the thickness of the consolidation grouting layer of the deep-buried tunnel, in meters; r is the radius of the deep-buried tunnel, in meters; H0 is the burial depth of the deep-buried tunnel, in meters; and D is the distance from the bottom of the deep borehole on the ground surface to the outer ring of the consolidation grouting layer.

[0054] Furthermore, each monitoring hole inside the tunnel is divided into two parts: a front section and a rear section. The front section, farther away from the deep-buried tunnel, is the measuring section and contains the piezometer; the rear section, closer to the deep-buried tunnel, is the sealing section.

[0055] The front section is filled with fine sand, and the piezometer is encased in the fine sand; the rear section is sealed with grout.

[0056] The length of the plugging section of the monitoring hole located in the outer rock layer is greater than the depth of the monitoring hole located in the consolidation grouting layer.

[0057] The length of the sealing section of the in-tunnel monitoring hole located within the consolidation grouting layer is greater than the depth of the in-tunnel monitoring hole located outside the lining layer of the deep-buried tunnel. Attached Figure Description

[0058] Figure 1 This is a schematic diagram of the surface deep borehole advanced stratified water pressure monitoring unit of the present invention;

[0059] Figure 2 This is a diagram showing the relationship between the location of the surface deep borehole and the deep-buried tunnel during the early stage of deep tunnel excavation according to the present invention;

[0060] Figure 3 This is a diagram showing the relationship between the location of the surface deep hole and the deep buried tunnel during the deep tunnel excavation process of this invention;

[0061] Figure 4 This invention determines the radius of influence r of groundwater at the tunnel face. d Schematic diagram;

[0062] Figure 5 This is a schematic diagram of the data wireless transmission unit of the present invention;

[0063] Figure 6 This is a schematic diagram of the structure of the porous water pressure monitoring unit inside the tunnel of the present invention;

[0064] Figure 7 This is a flowchart of the invention for monitoring external water pressure throughout the entire life cycle of a deeply buried tunnel;

[0065] Figure 8 This is a schematic diagram showing the drilling positions and depths of the monitoring holes in the three tunnels before the lining is constructed according to the present invention;

[0066] Figure 9 This is a schematic diagram showing the location of the built-in piezometer and fine sand filling in the three monitoring holes of the present invention;

[0067] Figure 10 This is a schematic diagram showing the location of the three monitoring holes inside the hole in this invention, where an early-strength agent is used to seal the holes;

[0068] Figure 11 This is a schematic diagram of the porous water pressure monitoring unit inside the tunnel before lining is constructed according to the present invention.

[0069] Figure 12 This is a schematic diagram of the porous water pressure monitoring unit inside the tunnel after the lining, consolidation grouting, and water filling operation of the present invention.

[0070] Among them, 101-Surface deep borehole; 102-Pierreometer; 103-Multi-channel data acquisition instrument; 104-Wireless transmission module; 105-Deep buried tunnel; 106-Tunnel excavation face; 107-Surface; 108-Mountain; 109-Stratum; 110-Signal cable; 111-Stratum boundary line; 112-Surface deep borehole plugging section; 113-Lined layer; 114-Consolidation grouting layer; 115-Rock stratum surrounding consolidation grouting layer; 116-Wireless receiving module; 117-Data storage server; 118-Data cloud platform; 119-Monitoring section; 201-Monitoring hole inside the tunnel; 2011-Measurement section; 2012-Plugging section; 202-Pierreometer; 203-Multi-channel data acquisition device; 205-Pierreometer signal cable; 209-Wire hole. Detailed Implementation

[0071] The present invention will be further illustrated below with reference to the accompanying drawings and embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. After reading this invention, any modifications of the invention in various equivalent forms by those skilled in the art will fall within the scope defined by the appended claims.

[0072] This invention monitors the external water pressure throughout the entire lifespan of a deeply buried tunnel by monitoring the pre-stratified water pressure in deep boreholes above the tunnel and the water pressure in porous structures at different depths within the tunnel. The deep-buried tunnel lifespan external water pressure monitoring system of this invention includes a surface deep borehole pre-stratified water pressure monitoring unit and a porous structure water pressure monitoring unit within the tunnel.

[0073] like Figure 1 As shown, the surface deep borehole advanced stratified water pressure monitoring unit includes a surface deep borehole 101, several piezometers 102, and a multi-channel data acquisition instrument 103. The surface deep borehole 101 is located in front of the excavation face 106 of the deep-buried tunnel 105 and above the completed deep-buried tunnel 105. The surface deep borehole 101 is drilled from the surface 107 to above the deep-buried tunnel 105, passing through different strata 109 of the mountain 108. At least one piezometer 102 is installed in each section of different strata 109 within the surface deep borehole 101. The measurement data output terminal of each piezometer 102 is connected to the signal input terminal of the multi-channel data acquisition instrument 103 via a signal cable 110.

[0074] To prevent the piezometers 102 inside the deep borehole 101 from interfering with each other and causing inaccurate measurement results, such as... Figure 1 As shown, in this invention, a sealing section 112 with a length greater than 2m is poured at the boundary line 111 between different strata within the deep borehole 101 of the surface, using an early-strength agent or concrete, to physically isolate two adjacent piezometers 102. During on-site construction, piezometers 102 are laid out from bottom to top within the deep borehole 101 of the surface. After each piezometer is laid out, the borehole section at the boundary line 111 is sealed with an early-strength agent or concrete using consolidation grouting technology to prevent interference between piezometers in different strata. The piezometer signal output cable 110 passes through the grouting sealing section and is connected to the signal input terminal of the surface multi-channel data acquisition instrument 103.

[0075] To monitor the entire lifecycle of deeply buried tunnels—from the start of construction to completion and operation—the formation and evolution of external water pressure within the tunnel, such as... Figures 1-3 As shown, the drilling location of the surface deep hole 101 of the present invention is located in front of the tunnel excavation face 106 when the deep buried tunnel 105 begins construction.

[0076] like Figure 2 , Figure 4 As shown, the expression for the total water head φ around the tunnel face 106 is:

[0077]

[0078] In the formula, a spatial rectangular coordinate system is established with point M1 (sink) as the origin, the excavation direction of the deep-buried tunnel 105 is the positive x-axis, the vertical upward direction is the positive z-axis, and the positive y-axis is determined according to the right-hand rule; Q is the flow rate at the tunnel face 106; k is the maximum permeability coefficient of the overlying stratum 109 of the deep-buried tunnel; r1 represents the distance from a certain position in the rock mass surrounding point M1 (sink) to point M1 (sink); r2 represents the distance from a certain position in the rock mass surrounding point M1 (sink) to point M2 (source); h0 is the vertical depth from the groundwater level to the axis of tunnel 105.

[0079] Furthermore, a total head percentage coefficient β is introduced to evaluate the degree of influence of the total head. The calculation formula is as follows:

[0080]

[0081] In the formula, φ represents the total water head of the rock mass surrounding point M1 (sink), in meters; h0 is the vertical depth from the groundwater level to the axis of tunnel 105, in meters; β represents the degree of influence of tunnel excavation on the initial groundwater, 0 < β < 1, dimensionless. The larger the value of β, the smaller the degree of influence.

[0082] To determine the drilling location of the surface deep borehole 101, it is first necessary to calculate the radius of influence r of the groundwater at the excavation face 106 of the deep-buried tunnel based on the total water head φ around the tunnel face 106. d The calculation formula is:

[0083]

[0084] In the formula, Q is the flow rate at the tunnel face 106; k is the maximum permeability coefficient of the overlying stratum 109; β is the total head percentage coefficient; h0 is the vertical depth from the groundwater level to the tunnel axis 105; r d This refers to the radius of influence of groundwater at the tunnel excavation face (106 meters). Preferably, β = 99%.

[0085] Considering the impact of drilling construction, based on the station K0 of the deep-buried tunnel face 106 and the radius of influence of groundwater r d The station number K of the on-site monitoring section ahead of tunnel face 106 is determined using the following formula:

[0086] K-K0=αr d

[0087] like Figure 2 As shown in the formula, station K is the station number of the on-site monitoring section 119, station K0 is the station number of the tunnel face 106, and r dThe radius of influence of groundwater at the tunnel excavation face 106 is given in meters. α is the safety factor. Considering that the tunnel face 106 is still advancing during the drilling process, α is generally taken as 1.5 to ensure that the monitoring section 119 is outside the influence range of the tunnel face 106.

[0088] After calculating the station K of the surface deep borehole 101, a borehole, namely surface deep borehole 101, is drilled downwards from the surface at station K, starting from station K at station 107. The diameter of the surface deep borehole is not less than 76 mm, and the depth h of the borehole should meet the following conditions (e.g., Figure 2 , 3 As shown):

[0089] h = H0 - rTD

[0090] In the formula, h is the drilling depth of the surface deep hole 101, in meters; T is the thickness of the consolidation grouting layer 114 of the deep-buried tunnel, in meters; r is the radius of the deep-buried tunnel 105, in meters; H0 is the burial depth of the deep-buried tunnel 105, which is the distance from the tunnel axis of the deep-buried tunnel 105 to the surface 107, in meters; D represents the distance from the bottom of the surface deep hole 101 to the outer ring of the consolidation grouting layer 114. In order to prevent the grout from entering the deep hole during high-pressure grouting and causing damage to the pore pressure gauge, D should generally be greater than 1.0m in this invention.

[0091] like Figure 5 As shown, the present invention also includes a wireless data transmission unit, which includes a wireless transmission module 104, a wireless receiving module 116, and a data storage server 117. The wireless receiving module 116 receives the water pressure of different strata above the deep-buried tunnel transmitted by the multi-channel data acquisition instrument 103 through the wireless transmission module 104, and stores the received data in the data storage server 117 and the data cloud platform 118 for data retrieval and analysis.

[0092] like Figure 1 , Figure 6 As shown, the multi-hole water pressure monitoring unit in the tunnel of the present invention is located directly below the surface deep hole 101, on the longitudinal section perpendicular to the tunnel axis, and the surface on which it is located, perpendicular to the tunnel axis, is the tunnel water pressure monitoring section 119.

[0093] The interior of the deep-buried tunnel 105 is a lining layer 113, which is surrounded by a consolidation grouting layer 114, and the outer surface of the consolidation grouting layer is an outer rock layer 115. The multi-hole water pressure monitoring unit inside the tunnel of the present invention includes at least three monitoring holes 201. All monitoring holes are located on the same cross section, namely the monitoring section 119 directly below the surface deep hole 101, and each monitoring hole has a different radial depth. One monitoring hole is located in the outer rock layer 115 and is used to monitor the water pressure in the outer rock layer. One monitoring hole is located in the consolidation grouting layer 114 and is used to monitor the water pressure in the consolidation grouting layer. One monitoring hole is close to the outer wall of the deep-buried tunnel 105 and is used to monitor the external water pressure applied to the lining layer 113 of the deep-buried tunnel.

[0094] A piezometer 202 is placed inside each monitoring borehole 201 in the tunnel. A multi-channel data acquisition instrument 203 and a wireless transmission module 104 are installed inside the deep-buried tunnel 105. The measurement data output terminal of each piezometer 202 is connected to the signal input terminal of the multi-channel data acquisition instrument 203 via a signal cable 205. The multi-channel data acquisition instrument 203 then stores the received data in a data storage server 117 and a data cloud platform 118 via the wireless transmission module 104 and a wireless receiving module 116, so that the control terminal or host computer can retrieve the data for analysis.

[0095] Each monitoring borehole 201 inside the tunnel is divided into two sections: a front section 2011, located away from the buried tunnel 105, is the measuring section and contains a piezometer 202; the rear section 2012, located closer to the buried tunnel 105, is the sealing section. The front section 2011 is filled with fine sand, and the piezometer 202 is encased within the fine sand. The rear section 2012 is sealed with an early-strength agent or concrete grout to prevent borehole leakage. The signal cable 205, connected to the signal output terminal of the piezometer, passes through the fine sand and the sealing section and connects to the signal input terminal of the multi-channel data acquisition instrument 203.

[0096] To accurately monitor the external water pressure in deeply buried tunnels, in a preferred embodiment of the present invention, three monitoring holes 201 with different radial depths and diameters of not less than 76 mm are drilled inside the tunnel. Each monitoring hole is divided into a measuring section and a sealing section. Figure 10 As shown, the depth and diameter of these three monitoring holes at different depths should satisfy the following relationship:

[0097]

[0098] In the formula, d 11 d 21 d 31 These represent the lengths of monitoring sections 2011 for the three monitoring holes with increasing depths, in meters (m); d 12 d 22 d 32The lengths of the plugging sections 2012 of the three monitoring holes, from smallest to largest depth, are represented in meters; T represents the thickness of the consolidation grouting layer 114 in the deep-buried tunnel, in meters.

[0099] like Figure 7 As shown, the method of this invention for monitoring external water pressure throughout the entire lifespan of a deeply buried tunnel is as follows:

[0100] S.1: Based on the station number 106 of the deep-buried tunnel face and the lithological characteristics of the strata, the station number of the on-site monitoring section 119 was determined.

[0101] S1.1 Based on the characteristics of the deep-buried tunnel 105, the source-sink theory model is used to determine the total water head φ around the tunnel face 106. The specific determination process is as follows:

[0102] like Figure 2 As shown, for the deeply buried tunnel 105, since the tunnel depth H0 is much greater than the tunnel radius r, that is:

[0103] H0>>r(1)

[0104] In the formula, H0 is the burial depth of the deep-buried tunnel 105 in meters (m), and r is the radius of the deep-buried tunnel 105 in meters (m). Therefore, relative to the entire mountain 108, the tunnel face 106 can be considered as a point, that is, an outlet point of groundwater in the mountain. Thus, the total water head φ around the tunnel face 106 can be determined using the classic source-sink theory model in seepage mechanics.

[0105] like Figure 4 As shown, in the source-sink theory model, the tunnel face 106 of the deep-buried tunnel is equivalent to a "sink", denoted as point M1. With the groundwater level as the line of symmetry, a hypothetical "source" is created, denoted as point M2. Then M1M2 = 2h0, where h0 is the vertical depth from the groundwater level to the axis of tunnel 105.

[0106] like Figure 4 As shown, according to Darcy's law i = vk, where i is the hydraulic gradient, v is the seepage velocity, and k is the permeability coefficient, based on the definitions of hydraulic gradient and seepage velocity, the rock mass surrounding point M1 (sink) has:

[0107]

[0108] In the formula, a spatial rectangular coordinate system is established with point M1 (sink) as the origin. The excavation direction of the deep-buried tunnel is the positive x-axis, the vertical upward direction is the positive z-axis, and the positive y-axis is determined according to the right-hand rule; φ represents the total water head of the rock mass surrounding point M1 (sink), in meters; Q is the flow rate at the tunnel face 106 (flow rate is positive for inflow and negative for outflow); r j This indicates the distance from a certain location in the rock mass surrounding point M1 (convergence) to point M.j The distance, j = 1, 2, in meters.

[0109] φ represents the total water head of the rock mass surrounding point M1 (sink). According to the definition of total water head, its expression is:

[0110] φ=z+p / γ w (3)

[0111] In the formula, z is the position head in meters (m), p is the pore water pressure in Pa, and γ is the pressure at the pore water level. w It is the specific gravity of water, measured in N / m³. 3 .

[0112] like Figure 4 As shown, r1 represents the distance from a certain location in the rock mass surrounding point M1 (sink) to point M1 (sink), and r2 represents the distance from a certain location in the rock mass surrounding point M1 (sink) to point M2 (source), satisfying the following relationship:

[0113]

[0114] like Figure 2 , 3 As shown, since the deep-buried tunnel 105 is often overlying multiple strata 109, and relevant permeability parameters can be obtained for each stratum 109 based on previous drilling data, in order to ensure that the model calculation results are more reliable, the permeability coefficient k of each stratum is taken. i The maximum value of k is taken as the permeability parameter of the entire overlying stratum, that is, the permeability coefficient k in equation (2) is taken according to the following formula:

[0115]

[0116] Furthermore, by integrating both sides of equation (2) and substituting the boundary conditions, we can obtain the analytical solution formula for the total water head of the rock mass surrounding point M1 (sink) based on the source-sink theory model. That is, the expression for the total water head φ around the tunnel face 106 is:

[0117]

[0118] like Figure 2 , 3 As shown in the formula, a spatial rectangular coordinate system is established with point M1 (sink) as the origin. The excavation direction of the deep-buried tunnel 105 is the positive x-axis, the vertical upward direction is the positive z-axis, and the positive y-axis is determined according to the right-hand rule. Q is the flow rate at the tunnel face 106; k is the maximum permeability coefficient of the overlying stratum 109 of the deep-buried tunnel; r1 represents the distance from a certain position in the rock mass surrounding point M1 (sink) to point M1 (sink); r2 represents the distance from a certain position in the rock mass surrounding point M1 (sink) to point M2 (source); and h0 is the vertical depth from the groundwater level to the axis of tunnel 105.

[0119] S1.2 Monitor the water inflow Q at the tunnel face 106 during the construction of the deep-buried tunnel 105, and determine the radius of influence r of the groundwater at the tunnel face 106 based on the total water head φ around the tunnel face 106. d ;

[0120] like Figure 4 As shown, considering that the total head at infinity in the source-sink theoretical model is still affected by the "sink," but in reality, the influence range of the tunnel face 106 is not infinite, the theoretical model does not match the actual situation. Therefore, in order to consider the impact of tunnel construction on the initial groundwater under actual conditions, this invention introduces a total head percentage coefficient β to evaluate the degree of influence of the total head. The calculation formula is as follows:

[0121]

[0122] In the formula, φ represents the total water head of the rock mass surrounding point M1 (sink), in meters; h0 is the vertical depth from the groundwater level to the axis of tunnel 105, in meters; β represents the degree of influence of tunnel excavation on the initial groundwater, 0 < β < 1, dimensionless. The larger the value of β, the smaller the degree of influence.

[0123] Furthermore, the closer β is to 1, the smaller the impact of tunnel excavation on the initial groundwater at this location. Preferably, when β = 99%, this location is considered the limiting distance for the impact of tunnel excavation on groundwater under the source-sink theory model. The expression for the total water head φ0 at this location is:

[0124] φ0=βh0=99%h0(8)

[0125] Furthermore, by combining equations (6) and (8) and setting φ = φ0, we can obtain the following equation:

[0126]

[0127] like Figure 4 As shown, Equation (9) is the expression for the influence boundary curve. In the equation, a spatial rectangular coordinate system is established with point M1 (sink) as the origin, the excavation direction of the deep-buried tunnel is the positive x-axis, the vertical upward direction is the positive z-axis, and the positive y-axis is determined according to the right-hand rule; Q is the flow rate at the tunnel face 106; k is the maximum permeability coefficient of the overlying stratum 109 of the deep-buried tunnel; β is the total water head percentage coefficient; h0 is the vertical depth from the groundwater level to the tunnel axis 105.

[0128] like Figure 4 As shown, Equation (9) is the expression for the boundary curve of the influence of tunnel excavation on groundwater under the source-sink theory model. It is a closed curve defined by the (x,z) coordinates on the xM1z plane.

[0129] like Figure 4 As shown, by transforming equation (9), we can obtain the expression for the left side of the x-coordinate of the boundary curve with respect to the z-coordinate. Since the curve is symmetrical about the z-axis, only the expression for the positive x-axis is given below:

[0130]

[0131] like Figure 4 As shown, Equation (10) is the expression for the influence of the boundary curve located in the first quadrant of the xM1z plane. In the equation, a spatial rectangular coordinate system is established with point M1 (sink) as the origin, the excavation direction of the deep-buried tunnel 105 is the positive x-axis, the vertical upward direction is the positive z-axis, and the positive y-axis is determined according to the right-hand rule; Q is the flow rate at the tunnel face 106; k is the maximum permeability coefficient of the overlying stratum 109 of the deep-buried tunnel; β is the total water head percentage coefficient; and h0 is the vertical depth from the groundwater level to the tunnel axis of 105.

[0132] like Figure 4 As shown, the radius of influence of groundwater at the tunnel excavation face is r. d The influence boundary curve can be determined by the following formula based on equation (10):

[0133] r d =x max (11)

[0134] In the formula, r d The radius of influence of groundwater at the tunnel excavation face is 106 m, x. max It is the maximum value of the x-coordinate that affects the boundary curve (10).

[0135] like Figure 4 As shown, based on the shape of the isohead line in the source-sink calculation model, under the above coordinate system, when z = 0, x takes the maximum value in curve (10), then x max The expression is:

[0136]

[0137] In the formula, Q is the flow rate at the tunnel face 106; k is the maximum permeability coefficient of the overlying stratum 109; β is the total water head percentage coefficient; h0 is the vertical depth from the groundwater level to the tunnel axis 105; x max It is the maximum value of the x-coordinate that affects the boundary curve (10).

[0138] Furthermore, by combining equations (11) and (12), the radius of influence r of groundwater at the excavation face of the deep-buried tunnel can be determined. d The calculation formula is:

[0139]

[0140] like Figure 4 As shown in the formula, Q is the flow rate at the tunnel face 106; k is the maximum permeability coefficient of the overlying stratum 109; β is the total water head percentage coefficient; h0 is the vertical depth from the groundwater level to the tunnel axis 105; r d This refers to the radius of influence of groundwater at the tunnel excavation face (106 meters). Preferably, β = 99%.

[0141] S1.3, based on the station number 106 of the deep-buried tunnel face and the radius of influence of groundwater r d The station number of the on-site monitoring section 119 in front of the tunnel face was determined.

[0142] The purpose of determining the station number of the on-site monitoring section 119 is to determine the drilling location of the surface deep hole 101.

[0143] First, the on-site monitoring section 119 and the tunnel face 106 are located in the same hydrogeological unit.

[0144] Secondly, in order to monitor the external water pressure throughout the entire life cycle of the deeply buried tunnel 105, such as Figure 1 As shown, the surface deep hole 101 needs to be drilled and all the piezometers 102 need to be installed before the deep buried tunnel 105 is excavated. Figure 2 This is a schematic diagram showing the location relationship between the surface deep-hole advanced stratified water pressure monitoring unit and the deep-buried tunnel 105 before excavation. Figure 3 This diagram illustrates the relationship between the surface deep-hole advanced stratified water pressure monitoring unit and the location of the deep-buried tunnel 105 during the entire tunneling process.

[0145] like Figures 2-4 As shown, the surface borehole 101 is located in front of the tunnel face 106 during the excavation of the deep-buried tunnel 105. Assume the station number of the tunnel face 106 is K0, the station number of the surface borehole 101 (i.e., the station number of monitoring section 119) is K, and the radius of influence of groundwater at the tunnel face is r. d :

[0146] K-K0=αr d (14)

[0147] In the formula, chainage K is the chainage of the on-site monitoring section, chainage K0 is the chainage at point 106 of the tunnel construction face, and r d The radius of influence of groundwater at the tunnel excavation face 106 is given in meters. α is the safety factor. Considering that the tunnel face 106 is still advancing during the drilling process, α is generally taken as 1.5 to ensure that the monitoring section 119 is outside the influence range of the tunnel face 106.

[0148] S.2: Directly above the on-site monitoring section 119, deploy a surface deep borehole advanced stratified water pressure monitoring unit to monitor the external water pressure of the deep buried tunnel throughout its entire life cycle.

[0149] S2.1. Directly above the monitoring section 119, drill downwards from the surface stratum 107 to the top of the deep-buried tunnel 105.

[0150] The diameter of the drilled hole shall not be less than 76mm.

[0151] like Figure 2 , 3 As shown, the depth h of the surface deep borehole 101 is:

[0152] h = H0 - rTD(15)

[0153] In the formula, h is the drilling depth of the surface deep hole 106, in meters; T is the thickness of the consolidation grouting layer 114 of the deep-buried tunnel, in meters; r is the radius of the deep-buried tunnel 105, in meters; H0 is the burial depth of the deep-buried tunnel 105, which is the distance from the tunnel axis to the ground surface, in meters; D represents the distance from the bottom of the surface deep hole 106 to the outer ring of the consolidation grouting layer 114. In order to prevent the grout from entering the deep hole during high-pressure grouting and causing damage to the borehole pressure gauge, D should generally be greater than 1.0m in this invention.

[0154] S2.2. Inside the borehole, from the bottom up, at least one piezometer is installed in each stratum section; at the stratum boundary 111 between two adjacent strata 109, a sealing section 112 with a length greater than 2m is poured with concrete or an early-strength agent to physically isolate the two adjacent piezometers 102.

[0155] S2.3. Deploy a multi-channel data acquisition instrument and a wireless data transmission unit on the ground surface; the measurement data output terminal of each piezometer is connected to the signal input terminal of the multi-channel data acquisition instrument via a signal cable.

[0156] Preferred, such as Figure 2 As shown, the tunnel should be excavated to a distance r from the borehole position at the tunnel face 106. d Prior to this, all work within the surface deep borehole 101 was completed, including the drilling of the surface deep borehole, the installation of piezometers inside the borehole, the plugging of the stratigraphic boundary area, and the construction of the data transmission channel.

[0157] S2.4. Use the piezometer 102 inside the deep borehole 101 on the surface to monitor the external water pressure of the buried tunnel throughout its entire life cycle.

[0158] S.3: When the deep-buried tunnel 105 is excavated to the monitoring section 119, a multi-hole water pressure monitoring unit will be installed in the tunnel to monitor the water pressure during the excavation of the deep-buried tunnel 105 and during its operation.

[0159] S3.1 At monitoring section 119 of the deep-buried tunnel, drill at least three monitoring holes 201 with different radial depths and diameters greater than 76 mm, extending outwards from the inside of the tunnel. Figure 8 As shown.

[0160] The radial depth of each monitoring hole in the tunnel is different. One monitoring hole is located in the outer rock layer 115 of the tunnel consolidation grouting layer and is used to monitor the average water pressure in the outer rock layer 115. Another monitoring hole is located in the tunnel consolidation grouting layer 114 and is used to monitor the average water pressure in the consolidation grouting layer. A third monitoring hole is located outside the lining layer of the deep-buried tunnel 105 and is used to monitor the water pressure applied to the outside of the lining layer 113 of the deep-buried tunnel.

[0161] like Figures 9-11 As shown, each monitoring hole inside the tunnel is divided into two parts: the front section and the rear section. The front section, which is far away from the deep-buried tunnel, is the measurement section 2011; the rear section, which is close to the deep-buried tunnel, is the sealing section 2012.

[0162] The piezometer readings within the measuring section of the outer rock stratum 115 surrounding the consolidated grouting layer of the deep-buried tunnel represent the average water pressure within the outer rock stratum 115. The measuring section of the deepest borehole used to monitor the water pressure within the outer rock stratum 115 must be sufficiently long; this invention recommends a length d. 31 The length should be at least 2.0m to avoid the measurement section for monitoring water pressure in the surrounding rock layers being too short, which could result in the measurement section being completely within the intact rock mass or rock fissures, causing the piezometer measurement results to be too high or too low.

[0163] The piezometer readings within the measurement section of the consolidated grout layer 114 in the deep-buried tunnel represent the average water pressure within the consolidated grout layer 114. The measurement section of the borehole used to monitor the water pressure within the consolidated grout layer 114 must be sufficiently long, generally determined by the thickness T of the consolidated grout layer 114, with the length d being the same as the thickness T of the consolidated grout layer. 21 This invention recommends this length d 21 Greater than 1.0m.

[0164] The piezometer readings located outside the lining layer 113 of the deeply buried tunnel represent the water pressure outside the lining layer 113. The measuring section of the borehole used to monitor the water pressure outside the lining layer 113 can be close enough to the tunnel wall (outside the lining layer 113), and the length d of the measuring section is generally determined according to the thickness of the lining layer 113. 11 This invention recommends this length d 11 Greater than 0.5m.

[0165] To prevent interference between the monitoring data of the three monitoring holes 201 within the same monitoring section 119, the length of the plugging section of the deeper monitoring hole must be greater than the depth of the shallower monitoring hole. That is, the length d of the plugging section of the monitoring hole used to monitor the water pressure within the consolidation grouting layer 114. 22The depth of the monitoring hole used to monitor the outer side of the lining layer 113 should be greater than the length of the plugged section d of the monitoring hole used to monitor the water pressure inside the outer rock layer 115. 32 It should be greater than the depth of the monitoring holes used in the consolidation grouting layer 114.

[0166] The relationship between the radial depths of the three monitoring holes inside the tunnel is as follows:

[0167]

[0168] In the formula, d 11 d 21 d 31 These represent the lengths of the monitoring sections for three monitoring holes, with depths increasing from smallest to largest, in meters (m); d 12 d 22 d 32 The numbers represent the lengths of the plugged sections of the three monitoring holes, from smallest to largest depth, in meters; T represents the thickness of the consolidation grout layer in meters.

[0169] At this time, the deep-buried tunnel had not been lined or consolidated with grout, and was in the initial stage of tunnel excavation. The depths of the three monitoring holes inside the tunnel, from shallow to deep, reached the outer side of the tunnel lining layer, the middle position of the consolidated grout layer (not yet constructed), and the outer rock position of the consolidated grout layer.

[0170] S3.2 Install a piezometer in the measuring section of each monitoring hole in the tunnel, and fill the entire measuring section with fine sand;

[0171] S3.3. A multi-channel data acquisition instrument 203 and a wireless data transmission unit are installed inside the tunnel. The measurement data output terminal of each piezometer 202 is connected to the signal input terminal of the multi-channel data acquisition instrument 203 via a signal cable. The multi-channel data acquisition instrument 203 then stores the received data in a server or cloud platform via the wireless data transmission unit for retrieval and analysis by the control terminal or host computer.

[0172] S3.4 Use an early-strength agent or concrete to seal the rear section of each monitoring hole with grout to prevent hole leakage.

[0173] S3.5. Use the piezometer in the monitoring hole inside the tunnel to monitor the water pressure outside the deep-buried tunnel.

[0174] S3.6. The lining is constructed sequentially, followed by grouting and water filling. The external water pressure of the deeply buried tunnel is monitored in real time using a multi-hole water pressure monitoring unit inside the tunnel. Figure 12 As shown.

[0175] Preferably, a threading hole 209 should be left for the piezometer cable in advance during the lining process to prevent damage to the cable.

[0176] Compared with existing technologies, this invention, through monitoring the pre-layered water pressure in deep boreholes at the surface and the water pressure in porous structures at different depths within the tunnel, can not only accurately determine the initial water head of deeply buried tunnels and the hydraulic connections between different strata, but also achieve real-time monitoring of the formation process and evolution of internal and external water pressure throughout the entire lifecycle of deeply buried tunnels, from the start of construction to completion and operation. This provides a reference for the design of long-distance deeply buried tunnels and their lining layers in the field of water conservancy and hydropower engineering, filling a gap in existing technologies.

Claims

1. A method for monitoring the evolution of external water pressure throughout the entire life cycle of a deeply buried tunnel, characterized in that: It includes the following steps: S1. Determine the station number of the on-site monitoring section based on the station number of the tunnel face and the lithological characteristics of the strata. S1.1 Using the source-sink theory model, determine the total water head around the tunnel face of a deeply buried tunnel. ; S1.2 Monitoring the water inflow at the tunnel face during deep-buried tunnel construction. Q And based on the total water head around the tunnel face Determine the radius of influence of groundwater at the tunnel face of a deeply buried tunnel. r d ; In the formula: Q This refers to the water inflow at the face of a deeply buried tunnel. k It is the maximum permeability coefficient of the stratum overlying the deep-buried tunnel; It is the total head percentage coefficient; h 0 is the vertical depth from the groundwater level to the tunnel axis; S1.3, Based on the station number of the deep-buried tunnel face and the radius of influence of groundwater. r d Determine the station number of the on-site monitoring section in front of the tunnel face. K : In the formula: K 0 represents the station number of the excavation face of a deeply buried tunnel. The radius of influence of groundwater at the excavation face of a deeply buried tunnel; For safety margin, it is generally taken as ; S.2: Directly above the on-site monitoring section, deploy surface deep borehole advanced stratified water pressure monitoring units to monitor the external water pressure of the deep buried tunnel throughout its entire life cycle; S2.

1. Drill a deep borehole directly above the monitoring section, starting from the surface strata and drilling downwards. The aperture is not less than 76mm; the depth of the hole h for: In the formula, The thickness of the consolidation grout layer for deeply buried tunnels is expressed in meters (m). r It is the radius of the deeply buried tunnel, in meters; The depth of the deep-buried tunnel is expressed in meters (m). To indicate the distance from the bottom of the deep borehole on the surface to the outer ring of the consolidation grouting layer of the deep-buried tunnel; S2.

2. In the deep borehole at the surface, at least one piezometer is installed in each stratum section from the bottom of the borehole upwards; a sealing section is injected at the boundary between two adjacent strata to physically isolate the two adjacent piezometers. S2.

3. Deploy a multi-channel data acquisition instrument and a wireless data transmission unit on the ground surface; the measurement data output terminal of each piezometer is connected to the signal input terminal of the multi-channel data acquisition instrument through a signal cable; the multi-channel data acquisition instrument stores the received data in a server or cloud platform through the wireless data transmission unit for retrieval and analysis by the control terminal or host computer. S2.4 Utilize piezometers in deep boreholes at the surface to monitor external water pressure throughout the entire life cycle of deeply buried tunnels; S.3: When the deep-buried tunnel is excavated to the monitoring section, a multi-hole water pressure monitoring unit is installed in the tunnel to monitor the water pressure during the excavation process and operation period of the deep-buried tunnel. S3.1 At the monitoring section of the deep-buried tunnel, at least three monitoring holes with radial depths greater than 76 mm shall be drilled from the inside of the tunnel outwards; one monitoring hole shall be located in the outer rock layer of the tunnel consolidation grouting layer to monitor the average water pressure in the outer rock layer; one monitoring hole shall be located in the tunnel consolidation grouting layer to monitor the average water pressure in the consolidation grouting layer; and one monitoring hole shall be located outside the lining layer of the deep-buried tunnel to monitor the water pressure applied to the outside of the lining layer of the deep-buried tunnel. Each monitoring hole inside the tunnel is divided into two parts: the front section, which is farther away from the deep-buried tunnel, is the measurement section; the rear section, which is closer to the deep-buried tunnel, is the sealing section. S3.

2. Install a piezometer in the measuring section of each monitoring hole in the tunnel, and fill the entire measuring section with fine sand, with the piezometer encased in the fine sand; S3.

3. A multi-channel data acquisition instrument and a wireless data transmission unit are installed inside the tunnel; the measurement data output terminal of each piezometer is connected to the signal input terminal of the multi-channel data acquisition instrument via a signal cable; the multi-channel data acquisition instrument stores the received data in a server or cloud platform via the wireless data transmission unit for retrieval and analysis by the control terminal or host computer. S3.

4. Seal the rear section of each monitoring hole in the tunnel with grout to prevent hole leakage; S3.

5. Use the piezometer in the monitoring hole inside the tunnel to monitor the water pressure outside the deep-buried tunnel; S3.

6. The lining is constructed in sequence, grouting is carried out, and water is filled for operation. The multi-hole water pressure monitoring unit inside the tunnel continues to monitor the water pressure outside the deep-buried tunnel in real time.

2. The method for monitoring the evolution of external water pressure throughout the entire life cycle of a deep-buried tunnel according to claim 1, characterized in that: The on-site monitoring section selected in step S1 is located in the same hydrogeological unit as the tunnel face during construction.

3. The method for monitoring the evolution of external water pressure throughout the entire life cycle of a deep-buried tunnel according to claim 2, characterized in that: The deployment of the surface deep borehole advanced stratified water pressure monitoring unit in step S2 requires the tunnel face to be excavated to a distance from the surface deep borehole. r d The scope was completed beforehand.

4. The method for monitoring the evolution of external water pressure throughout the entire life cycle of a deep-buried tunnel according to claim 3, characterized in that: In step S2.2, the length of the sealing section injected at the boundary between two adjacent strata is greater than 2m.

5. The method for monitoring the evolution of external water pressure throughout the entire life cycle of a deep-buried tunnel according to claim 4, characterized in that: In step S3.1, the three monitoring holes inside the tunnel reach depths from shallow to deep, respectively, reaching the outer side of the buried tunnel lining layer, the middle position of the pre-consolidated grouting layer, and the outer rock layer; and... The length of the plugged section of the monitoring hole located in the outer rock layer is greater than the depth of the monitoring hole located in the consolidated grouting layer. The length of the sealing section of the in-tunnel monitoring hole located within the consolidation grouting layer is greater than the depth of the in-tunnel monitoring hole located outside the lining layer of the deep-buried tunnel.

6. The method for monitoring the evolution of external water pressure throughout the entire life cycle of a deep-buried tunnel according to claim 5, characterized in that: The relationship between the radial depths of the three monitoring holes in step S3.1 is as follows: In the formula, d 11 , d 21 , d 31 These represent the lengths of the monitoring borehole measurement sections within the three boreholes, from smallest to largest depth, in meters. d 12 , d 22 , d 32 These represent the lengths of the monitoring hole sealing sections in three holes, with the hole depth increasing from smallest to largest, in meters. T This indicates the thickness of the consolidation grout layer surrounding the deep-buried tunnel, expressed in meters (m).

7. The method for monitoring the evolution of external water pressure throughout the entire life cycle of a deep-buried tunnel according to claim 6, characterized in that: The length of the monitoring hole measuring section located in the rock strata surrounding the consolidation grouting layer of the deep-buried tunnel. d 31 Greater than or equal to 2.0m; The length of the monitoring hole measuring section located within the consolidation grouting layer of the deep-buried tunnel. d 21 Greater than 1.0m; The length of the monitoring hole located outside the lining layer of the deep-buried tunnel is measured. d 11 Greater than 0.5m.

8. A system for monitoring external water pressure throughout the entire lifespan of a deeply buried tunnel, characterized in that: The method for monitoring the evolution of external water pressure throughout the entire life cycle of a deep-buried tunnel, as described in any one of claims 1-7, comprises a surface deep-hole advanced stratified water pressure monitoring unit, an in-tunnel multi-hole water pressure monitoring unit, and a data wireless transmission unit. The surface deep borehole advanced stratified water pressure monitoring unit includes a surface deep borehole, several piezometers, and a multi-channel data acquisition instrument. The surface deep borehole is located in front of the excavation face of the deep-buried tunnel and above the completed deep-buried tunnel; the surface deep borehole is drilled from the surface to above the deep-buried tunnel, passing through different strata of the mountain; at least one piezometer is installed in each stratum section of the surface deep borehole; the measurement data output terminal of each piezometer is connected to the signal input terminal of the multi-channel data acquisition instrument via a signal cable; a sealing section is injected at the stratum boundary line in the surface deep borehole; The in-tunnel multi-hole water pressure monitoring unit is located directly below the surface deep hole and on the monitoring section perpendicular to the tunnel axis; the in-tunnel multi-hole water pressure monitoring unit includes at least three in-tunnel monitoring holes, at least three piezometers, and a multi-channel data acquisition instrument; All monitoring holes inside the tunnel are located on the same cross section, and the radial depth of each monitoring hole is different; at least one monitoring hole is located in the rock strata surrounding the deep-buried tunnel, one monitoring hole is located in the consolidation grouting layer of the deep-buried tunnel, and one monitoring hole is located outside the lining layer of the deep-buried tunnel. A piezometer is placed in the monitoring hole of each tunnel; a multi-channel data acquisition instrument and a wireless transmission module are installed in the deep-buried tunnel; the measurement data output terminal of each piezometer is connected to the signal input terminal of the multi-channel data acquisition instrument via a signal cable; The multi-channel data acquisition instrument stores the received data in a server or cloud platform through the wireless data transmission unit, which can then be retrieved by the control terminal or host computer.

9. The deep-buried tunnel full-life-cycle external water pressure monitoring system according to claim 8, characterized in that: The station number of the deep borehole on the surface K With the excavation face pile number of the deep-buried tunnel K The relationship between 0 is: in: K 0 represents the station number of the excavation face of a deeply buried tunnel. The radius of influence of groundwater at the excavation face of a deeply buried tunnel; It is the safety factor; The depth of the surface deep borehole h for: In the formula, The thickness of the consolidation grout layer for deeply buried tunnels is expressed in meters (m). r It is the radius of the deeply buried tunnel, in meters; The depth of the buried tunnel is expressed in meters (m). It is the distance from the bottom of the deep borehole on the ground surface to the outer ring of the consolidated grouting layer.

10. The deep-buried tunnel full-life-cycle external water pressure monitoring system according to claim 9, characterized in that: Each monitoring hole inside the tunnel is divided into two parts: a front section and a rear section. The front section, which is farther away from the deep-buried tunnel, is the measuring section and contains the piezometer. The rear section, which is closer to the deep-buried tunnel, is the sealing section. The front section is filled with fine sand, and the piezometer is encased in the fine sand; the rear section is sealed with grout. The length of the plugged section of the monitoring hole located in the outer rock layer is greater than the depth of the monitoring hole located in the consolidated grouting layer. The length of the sealing section of the in-tunnel monitoring hole located within the consolidation grouting layer is greater than the depth of the in-tunnel monitoring hole located outside the lining layer of the deep-buried tunnel.

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