Method and system for determining external water pressure of tunnel based on four-layer hydrogeological structure

Abstract

The present invention provides a method and system for determining the external water pressure of a tunnel based on a four-layer hydrogeological structure, which relates to the technical field of underground tunnel engineering, including: obtaining the stratum information of the tunnel location, and determining the range of the natural aquifer and the natural waterproof layer according to the permeability coefficient of the stratum; determining the range of the engineering aquifer and the engineering waterproof layer based on the tunnel lining location; constructing a flow model of the four-layer hydrogeological structure based on the range of the natural aquifer, the natural waterproof layer, the engineering aquifer and the engineering waterproof layer; determining the external water pressure value on the tunnel lining based on the flow model of the four-layer hydrogeological structure. The external water pressure of the tunnel can be accurately determined, thereby taking into account the permeability coefficient of the tunnel lithosphere, the multi-layer nature of the rock layer, and the influence of the lining on the external water pressure reduction, and a comprehensive quantitative analysis, and the technical effect of the simple analysis process.

Description

Technical Field

[0001] The present invention relates to the technical field of underground tunnel engineering, and in particular to a method and system for determining the external water pressure of a tunnel based on a four-layer hydrogeological structure. Background Art

[0002] Different industry specifications have different provisions for the calculation of external water pressure of tunnel lining. At present, the main methods for determining the external water pressure of tunnels include reduction coefficient method, analytical solution method, numerical calculation method, seepage theory analysis method, hydrogeochemical method and physical simulation test.

[0003] Among them, the reduction coefficient method is applicable to the survey field and the construction excavation process, and does not consider the influence of the lining on the external water pressure reduction coefficient. Although the analytical solution takes into account the influence of the lining and even the grouting ring on the value of the external water pressure of the tunnel, it is only applicable to the case of a relatively simple hydrogeological structure. The range of consideration for the radius of the lithosphere is inaccurate, and the permeability coefficient of the lithosphere with water resistance (i.e., the influence on the external water pressure) is not considered. Summary of the invention

[0004] The purpose of the present invention is to provide a method and system for determining the water pressure outside a tunnel based on a four-layer hydrogeological structure, so as to solve the technical problem in the prior art that the water pressure outside a tunnel can only be determined when the hydrogeological structure is relatively simple.

[0005] In a first aspect, an embodiment of the present application provides a method for determining the external water pressure of a tunnel based on a four-layer hydrogeological structure, comprising:

[0006] Obtaining stratum information of the location where the tunnel is set, and determining the range of the natural aquifer and the natural water-resistant layer according to the permeability coefficient of the stratum;

[0007] Determine the scope of the project aquifer and the project water-proof layer based on the tunnel lining position;

[0008] Based on the range of the natural aquifer, the natural water-proof layer, the engineering aquifer and the engineering water-proof layer, a leakage model of a four-layer hydrogeological structure is constructed;

[0009] Based on the overflow model of the four-layer hydrogeological structure, the external water pressure value on the tunnel lining is determined.

[0010] In an optional embodiment, based on the ranges of the natural aquifer, the natural water-resistant layer, the engineering aquifer and the engineering water-resistant layer, a leakage model of a four-layer hydrogeological structure is constructed, including:

[0011] Based on the natural aquifer, the natural water-resistant layer and the engineering aquifer, a first overflow single-width model is constructed;

[0012] Based on the engineering water-resistant layer and the engineering aquifer, constructing a second overflow single-width model;

[0013] A overflow model of a four-layer hydrogeological structure is constructed according to the first overflow single-width model and the second overflow single-width model.

[0014] In an optional embodiment, based on the ranges of the natural aquifer, the natural water-resistant layer, the engineering aquifer and the engineering water-resistant layer, a leakage model of a four-layer hydrogeological structure is constructed, including:

[0015] Calculate the amount of groundwater that leaks through the natural impermeable layer and infiltrates into the engineering aquifer under the first leak single width model , and its calculation formula is as follows:

[0016]

[0017] Where r is the radius of the tunnel, in meters; is the lining thickness in meters; is the thickness of the engineering aquifer, in meters; is the permeability coefficient of the natural water-repellent layer, in meters per day; The thickness of the rock layer that is a natural water-repellent layer, in meters; is the hydrostatic pressure of groundwater, i.e., the acting head from the groundwater level to the tunnel centerline, in meters; is the external water pressure head on the tunnel lining, in meters;

[0018] Calculate the amount of groundwater that flows through the engineering waterproof layer and penetrates into the unpressurized tunnel under the second overflow single-width model , the calculation formula is as follows:

[0019]

[0020] In the formula, is the permeability coefficient of the lining, in meters per day.

[0021] In an optional embodiment, based on the ranges of the natural aquifer, the natural water-resistant layer, the engineering aquifer and the engineering water-resistant layer, a leakage model of a four-layer hydrogeological structure is constructed, including:

[0022] when hour, The expression is:

[0023]

[0024] in,

[0025] In an optional embodiment, determining the range of the natural aquifer and the natural water-resistant layer according to the permeability coefficient of the formation includes:

[0026] The permeability coefficient is The formation is defined as a natural aquifer;

[0027] The permeability coefficient is The strata are defined as naturally water-resistant layers.

[0028] In an optional embodiment, determining the range of the natural aquifer and the natural water-resistant layer according to the permeability coefficient of the formation includes:

[0029] For a deep tunnel, the permeability coefficient is The strata are defined as naturally water-resistant layers;

[0030] For tunnels with a small burial depth, the permeability coefficient is The strata are defined as naturally water-resistant layers.

[0031] In an optional embodiment, based on the tunnel lining position, the scope of the engineering aquifer and the engineering water-resistant layer is determined, including:

[0032] The loose zone outside the lining constitutes a groundwater accumulation and retention space as an engineering aquifer. The loose zone forms a space for accumulating and retaining groundwater due to construction excavation;

[0033] The lining of the tunnel is an engineering waterproof layer.

[0034] In a second aspect, an embodiment of the present application provides a system for determining the water pressure outside a tunnel based on a four-layer hydrogeological structure, including:

[0035] An acquisition module is used to acquire stratum information of the location where the tunnel is set, and determine the range of the natural aquifer and the natural water-resistant layer according to the permeability coefficient of the stratum;

[0036] Determination module, based on the location of tunnel lining, determines the scope of the project aquifer and the project impermeable layer;

[0037] A construction module, based on the range of the natural aquifer, the natural water-resistant layer, the engineering aquifer and the engineering water-resistant layer, constructs a leakage model of a four-layer hydrogeological structure;

[0038] The calculation module determines the external water pressure value on the tunnel lining based on the overflow model of the four-layer hydrogeological structure.

[0039] In a third aspect, an embodiment of the present application further provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of any one of the methods described in the first aspect when executing the computer program.

[0040] In a fourth aspect, an embodiment of the present application further provides a computer-readable storage medium, wherein the computer-readable storage medium stores machine-executable instructions. When the machine-executable instructions are called and executed by a processor, the machine-executable instructions prompt the processor to execute any of the methods described in the first aspect above.

[0041] The present invention provides a method and system for determining the external water pressure of a tunnel based on a four-layer hydrogeological structure. The method obtains the stratum information of the tunnel location and determines the range of the natural aquifer and the natural waterproof layer according to the permeability coefficient of the stratum; determines the range of the engineering aquifer and the engineering waterproof layer based on the tunnel lining location; constructs a flow model of the four-layer hydrogeological structure based on the range of the natural aquifer, the natural waterproof layer, the engineering aquifer and the engineering waterproof layer; and determines the external water pressure value on the tunnel lining based on the flow model of the four-layer hydrogeological structure. The external water pressure of the tunnel can be accurately determined, thereby taking into account the permeability coefficient of the tunnel lithosphere, the multi-layer nature of the rock layer, and the influence of the lining on the external water pressure reduction, and a comprehensive quantitative analysis is performed, and the analysis process is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0043] Figure 1 A schematic flow chart of a method for determining the external water pressure of a tunnel based on a four-layer hydrogeological structure provided in an embodiment of the present invention;

[0044] Figure 2 A schematic diagram of the structure of a four-layer hydrogeological structure model provided by an embodiment of the present invention;

[0045] Figure 3 A schematic diagram of a four-layer hydrogeological structure model including a grouting ring provided in an embodiment of the present invention;

[0046] Figure 4 A schematic diagram of the structure of a system for determining the external water pressure of a tunnel based on a four-layer hydrogeological structure provided by an embodiment of the present invention;

[0047] Figure 5 A schematic diagram of the structure of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0049] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] In the description of the present invention, it should be noted that the terms "first", "second", "third", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0051] In addition, the terms "horizontal", "vertical", etc. do not mean that the components are absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0052] Some embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0053] The methods for determining the external water pressure of a tunnel in the prior art are only applicable to situations where the hydrogeological structure is relatively simple, and the range of consideration for the radius of the lithosphere is inaccurate, and the permeability coefficient of the lithosphere with a water-resistant effect is not considered. Based on this, the present invention provides a method and system for determining the external water pressure of a tunnel based on a four-layer hydrogeological structure, by constructing a flow model of a four-layer hydrogeological structure of a pressure-free tunnel, and determining the external water pressure value on the tunnel lining, that is, considering the permeability coefficient of the tunnel lithosphere and reasonably selecting the radius of the lithosphere that affects the external water pressure, and considering the influence of the lining on the reduction of the external water pressure, thereby providing a reasonable analysis basis for the design of the tunnel excavation grouting ring. Therefore, the embodiments of the present invention can solve the technical problems of the inaccurate range of consideration for the radius of the lithosphere and the failure to consider the permeability coefficient of the lithosphere with a water-resistant effect.

[0054] Figure 1A flow chart of a method for determining the external water pressure of a tunnel based on a four-layer hydrogeological structure provided in an embodiment of the present application. Figure 1 As shown, the method comprises the following steps:

[0055] S110, obtaining stratum information of the location where the tunnel is set, and determining the range of the natural aquifer and the natural water-resistant layer according to the permeability coefficient of the stratum.

[0056] In order to solve the defect of single surrounding rock and geological conditions in analytical solution, the surrounding rock or mountain above the tunnel top is defined as a two-layer hydrogeological structure, which includes natural aquifer and natural water-resistant layer.

[0057] Among them, natural aquifers include weathered rock layers such as fully weathered, strongly weathered and weakly weathered upper zones, or rock bodies with strong dissolution weathering and fissure dissolution weathering, or some joint-intensive zones, fault zones, or confined aquifers on the upper part of slightly weathered and fresh rock layers. Groundwater is relatively rich in natural aquifers;

[0058] The natural water-repellent layer includes slightly weathered, fresh rock layers, or rock masses with weak fissure dissolution and weathering. The permeability coefficient in the natural water-repellent layer is more than 50 times lower than that of the natural aquifer. It is a relatively impermeable layer, and the groundwater in the natural water-repellent layer is scarce.

[0059] In some embodiments, determining the range of the natural aquifer and the natural water-resistant layer according to the permeability coefficient of the formation includes:

[0060] The permeability coefficient is The formation is defined as a natural aquifer;

[0061] The permeability coefficient is The strata are defined as naturally water-resistant layers.

[0062] Specifically, natural aquifers are defined by permeability coefficient, generally referring to highly permeable and moderately permeable aquifers, whose permeability coefficient is Or water permeability ;

[0063] The natural water-resistant layer is mainly defined by the permeability coefficient combined with the tunnel depth. For deep buried tunnels, it generally refers to the slightly permeable and extremely slightly permeable aquifers, and its permeability coefficient is Or water permeability For tunnels with a small burial depth, when the surrounding rock of the tunnel cannot reach the micro-permeable and ultra-micro-permeable layers, as long as the permeability coefficient meets the weak permeability requirements, that is It can also be a natural water-resistant layer, which is a continuously distributed stratum in the tunnel surrounding rock without other aquifers.

[0064] Furthermore, the permeability coefficient and thickness range of the natural water-resistant layer can be determined or divided according to appropriate hydrogeological tests conducted on site. The hydrogeological tests include layered water pressure test, pumping test, water injection test and tracer test to determine the permeability coefficient of the natural aquifer, and geological drilling, geophysical exploration, hydrogeological survey and other methods to determine the thickness range of the natural aquifer.

[0065] S120. Based on the tunnel lining position, determine the scope of the project aquifer and the project impermeable layer.

[0066] Due to the incomplete drainage of the tunnel lining, groundwater accumulates on the outer surface of the lining, forming external water pressure on the lining. From an engineering perspective, the lining is a water barrier that blocks the seepage of groundwater into the tunnel.

[0067] In some embodiments, the scope of the engineering aquifer and the engineering water-resistant layer is determined according to the tunnel lining position, including:

[0068] The loose zone outside the lining constitutes a groundwater accumulation and retention space as an engineering aquifer. The loose zone forms a space for accumulating and retaining groundwater due to construction excavation;

[0069] The lining of the tunnel is an engineering waterproof layer.

[0070] Specifically, the loose zone formed on the outer surface of the tunnel lining during the surrounding rock excavation process constitutes the groundwater accumulation and retention space as the engineering aquifer, that is, the groundwater enters the groundwater accumulation and retention space outside the lining from the natural aquifer through the natural water-resistant layer as the engineering aquifer;

[0071] The lining of the tunnel is regarded as an engineering waterproof layer, that is, under the action of external water pressure on the lining, groundwater passes through the lining and enters the tunnel. The engineering waterproof layer also includes a lining with drainage holes and other measures.

[0072] S130. Construct a overflow model of a four-layer hydrogeological structure based on the ranges of the natural aquifer, the natural water-resistant layer, the engineering aquifer and the engineering water-resistant layer.

[0073] Among them, based on the fact that the groundwater seepage characteristics are controlled by the hydrogeological structure, a overflow model of the four-layer hydrogeological structure of the unpressured tunnel was established, so as to determine the external water pressure value on the lining.

[0074] It should be noted that in the four-layer hydrogeological structure of the embodiment of the present invention, the process of groundwater seepage from the natural aquifer to the engineering aquifer is called overflow, that is, the upper and lower aquifers are separated by a weak permeable layer, and the water head values ​​of the two aquifers are different, and the groundwater in the high-head aquifer replenishes the low-head aquifer through the middle weak permeable layer. The overflow direction and the amount of water obtained or lost through overflow are controlled by the pressure head difference on both sides of the weak permeable layer, and are affected by the thickness and permeability coefficient of the weak permeable layer.

[0075] A overflow model of a four-layer hydrogeological structure is constructed with the tunnel as the new discharge datum surface, that is, the center line of the tunnel is taken as the base point. The natural aquifer is a high-head aquifer, and the engineering aquifer is a low-head aquifer. The natural aquifer recharges the engineering aquifer through the natural impermeable layer. The natural aquifer loses water through overflow, and the engineering aquifer gains water through overflow. The two water volumes are equal. The water volume is controlled by the head difference on both sides of the natural impermeable layer, and is also affected by the thickness and permeability coefficient of the natural impermeable layer.

[0076] like Figure 2 As shown in the figure, it is assumed that the height from the groundwater level of the high-head natural aquifer to the static water level of the tunnel centerline is , the water head height of the low-head engineering aquifer is , is also the external water pressure on the lining, then the head difference is The head difference is the driving force that drives groundwater through the natural water-resistant layer. When groundwater seeps into the unpressured tunnel, It is also the driving force that drives groundwater through the engineering waterproof layer, namely the lining. Under the action of these two driving forces, groundwater overflows twice in the four-layer hydrogeological structure.

[0077] In some embodiments, based on the ranges of the natural aquifer ①, the natural water-resistant layer ②, the engineering aquifer ③ and the engineering water-resistant layer ④, a leakage model of a four-layer hydrogeological structure is constructed, including:

[0078] Based on the natural aquifer, the natural water-resistant layer and the engineering aquifer, a first overflow single-width model is constructed;

[0079] Based on the engineering water-resistant layer and the engineering aquifer, constructing a second overflow single-width model;

[0080] A overflow model of a four-layer hydrogeological structure is constructed according to the first overflow single-width model and the second overflow single-width model.

[0081] Among them, according to Darcy's law, first, calculate the amount of groundwater that leaks through the natural impermeable layer and infiltrates into the engineering aquifer under the first leak single width model: , and its calculation formula is as follows:

[0082]

[0083] Where r is the radius of the tunnel, in meters; is the lining thickness in meters; is the thickness of the engineering aquifer, in meters; is the permeability coefficient of the natural water-repellent layer, in meters per day; The thickness of the rock layer that is a natural water-repellent layer, in meters; is the hydrostatic pressure of groundwater, i.e., the acting head from the groundwater level to the tunnel centerline, in meters; It is the external water pressure head on the tunnel lining, measured in meters.

[0084] in, The thickness of the engineering aquifer is generally determined based on the actual situation of the loosened zone of the surrounding rock during tunnel excavation. During the survey period, an empirical constant of 1.0 m can be used. is the permeability coefficient of the natural water-resistant layer. When the tunnel surrounding rock is relatively complete or completely slightly weathered, fresh rock mass, the surrounding rock category generally corresponds to Class II or III surrounding rock, which can form a natural water-resistant layer. Equal to the permeability coefficient of the tunnel's micro-new rock mass surrounding rock , for deep buried tunnels, Should satisfy , about K< .

[0085] Then, the amount of groundwater that leaks through the engineering waterproof layer and seeps into the unpressurized tunnel under the second leak single-width model is calculated. , the calculation formula is as follows:

[0086]

[0087] In the formula, It is the permeability coefficient of the lining, in meters per day. When the lining contains drainage measures such as drainage holes, the comprehensive permeability coefficient of the drainage measures shall be considered.

[0088] Finally, when When, that is:

[0089] Through the above formula, we can get The expression is:

[0090]

[0091] make:

[0092]

[0093] but The expression can be:

[0094]

[0095] S140. Determine the external water pressure value on the tunnel lining based on the overflow model of the four-layer hydrogeological structure.

[0096] In the overflow model of the four-layer hydrogeological structure of the present invention, groundwater overflows twice. When the groundwater overflows from the natural aquifer through the natural water-resistance layer into the engineering aquifer, Greater than the amount of groundwater flowing from the project aquifer to the project water-resistant layer into the tunnel When the external water pressure on the lining The amount of groundwater entering the tunnel will continue to rise. The water head difference on both sides of the natural water-resistant layer will continue to increase. Then it keeps decreasing. When the external water pressure on the outer surface of the tunnel lining reaches a stable state, the value of the external water pressure on the lining is the actual required external water pressure on the lining. .

[0097] Figure 3 A four-layer hydrogeological structure model containing a grouting ring is provided in an embodiment of the present application, which is used to determine the external water pressure of a tunnel at a special location.

[0098] The present invention takes the fractured rock mass such as the fault zone as a special part as an example. In the hydrogeological structure, the fault zone can generally be regarded as a permeable channel. When the tunnel passes through the fault zone, it can be considered that the natural water-resistant layer is missing in the four-layer hydrogeological structure, and the tunnel lining is almost all natural aquifers, that is, the external water pressure reduction coefficient is close to 1, which is unacceptable in deep buried tunnels. Therefore, in engineering practice, it is generally necessary to grout the tunnel surrounding rock to form a grouting circle outside the lining, such as Figure 3 As shown in the figure, the permeability coefficient of the grouting circle can reach weak or slight permeability according to the design and treatment requirements. The grouting circle constitutes a waterproof layer and can be considered as an artificial waterproof layer.

[0099] The treated grouting circle is used as a natural waterproof layer②. The four-layer hydrogeological structure overflow model can be constructed by the above method. In the model, the thickness of the grouting circle is used as the Replace the thickness of the natural waterproof layer , using the permeability coefficient of the grouting ring Permeability coefficient that replaces the natural water-repellent layer , so the calculation coefficient m of the external water pressure on the tunnel lining is changed to:

[0100]

[0101] The thickness of the grouting ring and the permeability coefficient of the grouting ring will be determined based on the appropriate external water pressure value that the lining can withstand and the reasonable tunnel drainage in the groundwater environment.

[0102] This application uses a overflow model to construct a overflow model for a four-layer hydrogeological structure. The external water pressure value on the tunnel lining is determined through the model. While taking into account the permeability coefficient of the tunnel lithosphere, the multi-layer nature of the rock layer, and the influence of the lining on the external water pressure reduction are taken into account, thereby enabling a comprehensive quantitative analysis. The analysis process is simple and the analysis results are more reasonable and accurate.

[0103] For example, take a typical granite block rock section in a deep buried tunnel of a certain project as an example. This section of the tunnel is located in the hinterland of a mountain, and the surrounding rock category is mainly Class III, of which Class III accounts for 55%, Class II accounts for 30%, and Class IV accounts for 15%.

[0104] Among them, natural aquifers are mainly weakly weathered and strongly weathered metamorphic rocks, namely quartz schist, quartz mica schist intercalated with metamorphic quartz sandstone, and the hydrostatic head H is generally above 600 meters. =575 m;

[0105] The upper part of the natural water-resistant layer is slightly weathered metamorphic rock with a thickness of 120 to 200 meters, and the lower part is slightly weathered granite porphyry with a thickness of 350 to 450 meters. After water pressure test verification, the permeability coefficient of slightly weathered metamorphic rock, granite porphyry and other blocks is =6.1× cm / s = 0.005 m / day, which can reach the standard of natural water-resistant layer. According to the survey and drilling, the thickness of natural water-resistant layer can reach =500 m;

[0106] The engineering aquifer is the loose zone on the outer surface of the lining, and its thickness is tentatively set at =1m;

[0107] The waterproof layer of the project is an open TBM excavated non-pressure circular tunnel with an inner diameter of r = 4.10 meters. The lining material is C35 reinforced concrete. The thickness of the lining of Class II surrounding rock is 30 cm, and the thickness of the lining of other surrounding rock is 40 cm. The representative thickness is taken = 0.4 m, select a representative value based on the magnitude of the initial permeability coefficient of the lining, generally 5× Meters per second, that is =4.3× m / day;

[0108] Substitute the above parameters into the above The external water pressure on the tunnel lining can be obtained from the expression of and m. =0.095MPa, about 9.5 meters of water head. According to the existing survey specifications (GB50487), the tunnel is located in a micro-permeable stratum, and the external water pressure reduction coefficient ranges from 0.1 to 0.2. Therefore, the minimum external water pressure also reaches 57.5 meters of water head, about 0.56MPa, which greatly exceeds the external water pressure value determined by this method. In order to reduce the impact of external water pressure on the lining, grouting measures may be taken, which increases the project investment cost. Even in accordance with the design specification "Design Specifications for Hydraulic Tunnels" (SL279-2016), the value of the external water pressure reduction coefficient is taken according to the groundwater activity state after tunnel excavation. When the groundwater activity state is dry or wet on the tunnel wall, the empirical value range of the reduction coefficient is 0.00~0.20, which is relatively large. Even if the average value is 0.10, the determined external water pressure value is still too large, which is not as quantitative and accurate as this method.

[0109] For example, take a tunnel section of a certain project as an example. This tunnel section is located at the bottom of a canyon in a certain mountain, and the surrounding rock type is mainly Class III, of which Class III accounts for 79%, Class IV accounts for 12%, and Class IV accounts for 8%.

[0110] Natural aquifers are mainly slightly weathered, partially and weakly weathered marble or weakly and slightly weathered marble, carbonaceous marble intercalated with metamorphic quartz sandstone. The vertical depth distribution of natural aquifers has no direct correlation with the weathering state, but is mainly related to two aspects: one is the overall strong karst layer, that is, the depth of the floor with caves; the other is the distribution range of the water-rich wide fault and its influence zone in the tunnel direction, the static head =180 m;

[0111] The natural water-resistant layer is slightly weathered marble or marble intercalated with metamorphic quartz sandstone, mainly a weak karst layer, with no exposed caves. In the karst area, the natural water-resistant layer belongs to a weak hydraulic connection layer, located below the influence depth of the modern karst layer, i.e., the strong hydraulic connection layer. The thickness of the natural water-resistant layer is determined by combining the conventional water pressure test and the new layered water pressure test on site to determine the permeability coefficient and thickness of the natural water-resistant layer. After determining the permeability coefficient =9.8× cm / s = 0.008 m / day. The thickness of the natural water-resistant layer is determined by analyzing the hydraulic connection of water-pressing sections at different depths. =30m;

[0112] The engineering aquifer is the loose zone on the outer surface of the lining, and its thickness is tentatively set at =1m;

[0113] The waterproof layer of the project, this section of the tunnel is a pressure-free circular tunnel excavated by the drilling and blasting method, with an inner diameter of r = 4.05 meters, and the lining material is C35 reinforced concrete, of which the lining thickness of Class III surrounding rock is 45 cm, the lining thickness of Class IV surrounding rock is 50 cm, and the lining thickness of Class V surrounding rock is about 55 cm, taking the representative thickness = 0.5 m, select a representative value based on the magnitude of the initial permeability coefficient of the lining, generally 5× Meters per second, that is =4.3× m / day;

[0114] Substitute the above parameters into the above The external water pressure on the tunnel lining can be obtained from the expression of and m. =0.55MPa, about 56 meters water head. According to the existing survey specifications (GB50487), the tunnel is located in a weak karst stratum and is slightly permeable. The external water pressure reduction coefficient ranges from 0.1 to 0.2. Therefore, the minimum external water pressure is 18 meters water head and the maximum is 36 meters water head, which underestimates the actual possible external water pressure value.

[0115] The above two examples both show that it is inaccurate to determine the external water pressure reduction coefficient based solely on the properties of the rock and soil layer where the tunnel is located, i.e. the permeability grade or the state of groundwater activity after excavation, without considering other rock and soil layers above the top of the deep buried tunnel or the thickness of the tunnel surrounding rock.

[0116] In summary, the method for determining the external water pressure of a tunnel based on a four-layer hydrogeological structure provided by the embodiment of the present invention has the following advantages:

[0117] 1. The method of the present invention not only takes into account the permeability coefficient of the tunnel lithosphere, but also adopts a suitable hydrogeological test method to select the radius of the lithosphere that affects the external water pressure, that is, the multi-layered nature of the rock layer is taken into account, and the influence of the lining on the external water pressure reduction is taken into account. The established model is more in line with the groundwater seepage characteristics after tunnel excavation. The quantitative analysis method has comprehensive elements, a relatively simple process, and more reasonable and accurate results, avoiding complex three-dimensional numerical analysis;

[0118] 2. The method of the present invention can provide a more reasonable analysis basis for the design of tunnel excavation grouting rings. Some deep buried tunnel sections can save grouting costs and reduce project investment. Some water-rich strata can more reasonably determine the thickness of the natural waterproof layer. By adding grouting measures, the safety of tunnel excavation and operation and maintenance can be ensured.

[0119] 3. The method of the present invention is carried out in combination with basic survey work, avoiding pure numerical analysis or physical simulation that deviates from reality. The new stratified water pressure test method is simple to operate and can be simply improved on the basis of the existing water pressure test device. It can provide a new criterion for the value of the external water pressure reduction coefficient for the current national standard "Specifications for Geological Survey of Water Conservancy and Hydropower Engineering".

[0120] Corresponding to the above method for determining the water pressure outside the tunnel based on the four-layer hydrogeological structure, the embodiment of the present invention also provides a system for determining the water pressure outside the tunnel based on the four-layer hydrogeological structure. Figure 4A schematic diagram of a system for determining the external water pressure of a tunnel based on a four-layer hydrogeological structure is shown, the system comprising:

[0121] The acquisition module 210 is used to acquire the stratum information of the location where the tunnel is set, and determine the range of the natural aquifer and the natural water-resistant layer according to the permeability coefficient of the stratum;

[0122] A determination module 220 determines the scope of the engineering aquifer and the engineering water-resistant layer based on the tunnel lining position;

[0123] A construction module 230 is used to construct a leakage model of a four-layer hydrogeological structure based on the range of the natural aquifer, the natural water-resistant layer, the engineering aquifer and the engineering water-resistant layer;

[0124] The calculation module 240 determines the external water pressure value on the tunnel lining based on the overflow model of the four-layer hydrogeological structure.

[0125] In some embodiments, the acquisition module 210 is further configured to:

[0126] Based on the natural aquifer, the natural water-resistant layer and the engineering aquifer, a first overflow single-width model is constructed;

[0127] Based on the engineering water-resistant layer and the engineering aquifer, constructing a second overflow single-width model;

[0128] A overflow model of a four-layer hydrogeological structure is constructed according to the first overflow single-width model and the second overflow single-width model.

[0129] In some embodiments, the construction module 230 is further configured to:

[0130] Calculate the amount of groundwater that leaks through the natural impermeable layer and infiltrates into the engineering aquifer under the first leak single width model , and its calculation formula is as follows:

[0131]

[0132] Where r is the radius of the tunnel, in meters; is the lining thickness in meters; is the thickness of the engineering aquifer, in meters; is the permeability coefficient of the natural water-repellent layer, in meters per day; The thickness of the rock layer that is a natural water-repellent layer, in meters; is the hydrostatic pressure of groundwater, i.e., the acting head from the groundwater level to the tunnel centerline, in meters; is the external water pressure head on the tunnel lining, in meters;

[0133] Calculate the amount of groundwater that flows through the engineering waterproof layer and penetrates into the unpressurized tunnel under the second overflow single-width model , the calculation formula is as follows:

[0134]

[0135] In the formula, is the permeability coefficient of the lining, in meters per day.

[0136] In some embodiments, the construction module 230 is further configured to:

[0137] when hour, The expression is:

[0138]

[0139] in,

[0140] In some embodiments, the construction module 230 is further configured to:

[0141] The permeability coefficient is The formation is defined as a natural aquifer;

[0142] The permeability coefficient is The strata are defined as naturally water-resistant layers.

[0143] In some embodiments, the construction module 230 is further configured to:

[0144] For a deep tunnel, the permeability coefficient is The strata are defined as naturally water-resistant layers;

[0145] For tunnels with a small burial depth, the permeability coefficient is The strata are defined as naturally water-resistant layers.

[0146] In some embodiments, the determination module 220 is further configured to:

[0147] The loose zone outside the lining constitutes a groundwater accumulation and retention space as an engineering aquifer. The loose zone forms a space for accumulating and retaining groundwater due to construction excavation;

[0148] The lining of the tunnel is an engineering waterproof layer.

[0149] The implementation principle and technical effects of the device provided in the embodiments of the present application are the same as those of the aforementioned method embodiments. For the sake of brief description, for matters not mentioned in the device embodiment, reference may be made to the corresponding contents in the aforementioned method embodiments.

[0150] like Figure 5As shown, an electronic device 600 provided in an embodiment of the present application includes: a processor 601, a memory 602 and a bus, the memory 602 stores machine-readable instructions executable by the processor 601, and when the electronic device is running, the processor 601 communicates with the memory 602 through the bus, and the processor 601 executes the machine-readable instructions to perform the steps of the method for determining the external water pressure of a tunnel based on a four-layer hydrogeological structure as described above.

[0151] Specifically, the above-mentioned memory 602 and processor 601 can be general-purpose memory and processor, which are not specifically limited here. When the processor 601 runs the computer program stored in the memory 602, it can execute the above-mentioned method for determining the external water pressure of the tunnel based on the four-layer hydrogeological structure.

[0152] The processor 601 may be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method can be completed by the hardware integrated logic circuit or software instructions in the processor 601. The above processor 601 can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The methods, steps and logic block diagrams disclosed in the embodiments of the present application can be implemented or executed. The general processor can be a microprocessor or the processor can also be any conventional processor, etc. The steps of the method disclosed in the embodiments of the present application can be directly embodied as a hardware decoding processor for execution, or a combination of hardware and software modules in the decoding processor for execution. The software module may be located in a storage medium mature in the art such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory, or an electrically erasable programmable memory, a register, etc. The storage medium is located in the memory 602, and the processor 601 reads the information in the memory 602 and completes the steps of the above method in combination with its hardware.

[0153] Corresponding to the above-mentioned method for determining the external water pressure of a tunnel based on a four-layer hydrogeological structure, an embodiment of the present application also provides a computer-readable storage medium, which stores machine-executable instructions. When the computer-executable instructions are called and executed by a processor, the computer-executable instructions prompt the processor to execute the steps of the above-mentioned method for determining the external water pressure of a tunnel based on a four-layer hydrogeological structure.

[0154] The system for determining the external water pressure of a tunnel based on a four-layer hydrogeological structure provided in the embodiment of the present application can be specific hardware on the device or software or firmware installed on the device. The device provided in the embodiment of the present application, its implementation principle and the technical effect produced are the same as those in the aforementioned method embodiment. For the sake of brief description, for the parts not mentioned in the device embodiment, reference can be made to the corresponding contents in the aforementioned method embodiment. Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working processes of the systems, devices and units described above can all refer to the corresponding processes in the aforementioned method embodiment, and will not be repeated here.

[0155] In the embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, and the indirect coupling or communication connection of devices or units can be electrical, mechanical or other forms.

[0156] For another example, the flowchart and block diagram in the accompanying drawings show the possible architecture, functions and operations of the device, method and computer program product according to multiple embodiments of the present application. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of the code, and a part of the module, program segment or code contains one or more executable instructions for realizing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of the boxes in the block diagram and / or flowchart can be implemented with a dedicated hardware-based system that performs a specified function or action, or can be implemented with a combination of dedicated hardware and computer instructions.

[0157] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0158] In addition, each functional unit in the embodiments provided in the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0159] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including a number of instructions to enable an electronic device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk, and other media that can store program codes.

[0160] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for determining the external water pressure of a tunnel based on a four-layer hydrogeological structure, characterized in that: include: The stratum information of the tunnel location is obtained, and the range of the natural aquifer and the natural water-resistant layer is determined according to the permeability coefficient of the stratum, wherein the permeability coefficient of the stratum is The formation is defined as a natural aquifer; the permeability coefficient of the formation is The strata are defined as naturally water-resistant layers; Based on the position of the tunnel lining, the scope of the engineering aquifer and the engineering waterproof layer is determined, wherein the loose circle outside the lining constitutes the groundwater accumulation and retention space as the engineering aquifer, and the loose circle forms a space for accumulating and retaining groundwater due to construction excavation; the tunnel lining is the engineering waterproof layer; Based on the range of the natural aquifer, the natural water-resistant layer, the engineering aquifer and the engineering water-resistant layer, a flow model of a four-layer hydrogeological structure is constructed, wherein the flow model of a four-layer hydrogeological structure is constructed including: constructing a first flow single-width model based on the natural aquifer, the natural water-resistant layer and the engineering aquifer; constructing a second flow single-width model based on the engineering water-resistant layer and the engineering aquifer; constructing a flow model of a four-layer hydrogeological structure according to the first flow single-width model and the second flow single-width model; Based on the overflow model of the four-layer hydrogeological structure, the external water pressure value on the tunnel lining is determined.

2. The method according to claim 1, characterized in that Based on the range of the natural aquifer, the natural water-proof layer, the engineering aquifer and the engineering water-proof layer, a leakage model of a four-layer hydrogeological structure is constructed, including: Calculate the amount of groundwater that leaks through the natural impermeable layer and infiltrates into the engineering aquifer under the first leak single width model , and its calculation formula is as follows: Where r is the radius of the tunnel, in meters; is the lining thickness in meters; is the thickness of the engineering aquifer, in meters; is the permeability coefficient of the natural water-repellent layer, in meters per day; The thickness of the rock layer that is a natural water-repellent layer, in meters; is the hydrostatic pressure of groundwater, i.e., the acting head from the groundwater level to the tunnel centerline, in meters; is the external water pressure head on the tunnel lining, in meters; Calculate the amount of groundwater that flows through the engineering waterproof layer and penetrates into the unpressurized tunnel under the second overflow single-width model , the calculation formula is as follows: In the formula, is the permeability coefficient of the lining, in meters per day.

3. The method according to claim 2, characterized in that Based on the range of the natural aquifer, the natural water-proof layer, the engineering aquifer and the engineering water-proof layer, a leakage model of a four-layer hydrogeological structure is constructed, including: when hour, The expression is: in, 4. A system for determining the external water pressure of a tunnel based on a four-layer hydrogeological structure, characterized in that: include: The acquisition module is used to obtain the stratum information of the tunnel location and determine the range of the natural aquifer and the natural water-resistant layer according to the permeability coefficient of the stratum, wherein the permeability coefficient of the stratum is The formation is defined as a natural aquifer; the permeability coefficient of the formation is The strata are defined as naturally water-resistant layers; A determination module determines the scope of the engineering aquifer and the engineering waterproof layer based on the position of the tunnel lining, wherein the loose circle outside the lining constitutes the groundwater accumulation and retention space as the engineering aquifer, and the loose circle forms a space for accumulating and retaining groundwater due to construction excavation; the lining of the tunnel is the engineering waterproof layer; A construction module is provided for constructing a flow model of a four-layer hydrogeological structure based on the range of the natural aquifer, the natural water-resistant layer, the engineering aquifer and the engineering water-resistant layer, wherein the construction of the flow model of the four-layer hydrogeological structure includes: constructing a first flow single-width model based on the natural aquifer, the natural water-resistant layer and the engineering aquifer; constructing a second flow single-width model based on the engineering water-resistant layer and the engineering aquifer; constructing a flow model of the four-layer hydrogeological structure according to the first flow single-width model and the second flow single-width model; The calculation module determines the external water pressure value on the tunnel lining based on the overflow model of the four-layer hydrogeological structure.

5. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 4 are implemented.

6. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores machine-executable instructions. When the machine-executable instructions are called and executed by a processor, the machine-executable instructions cause the processor to execute the method according to any one of claims 1 to 4.

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