A deep tunnel excavation compensation method

Abstract

The present application relates to the technical field of tunnel surrounding rock stability control, and provides an excavation compensation method for a deep buried tunnel. The method comprises: obtaining engineering geological information of a deep buried tunnel; determining the type of engineering disaster based on the engineering geological information; determining the excavation compensation support strategy of the surrounding rock of the deep buried tunnel based on the type of engineering disaster; and performing supplementary support control on the surrounding rock of the deep buried tunnel based on the excavation compensation support strategy. The supplementary support strategy can reduce the difference between the radial stress and the initial ground stress of the surrounding rock of the deep buried tunnel to within a preset approximate value range, and further can effectively prevent the stress concentration phenomenon of the tangential stress. After the excavation of the deep buried tunnel, high prestressed excavation compensation support is applied in time to restore the three-dimensional initial stress state of the surrounding rock as much as possible, thereby improving the bearing capacity of the surrounding rock, fully mobilizing the strength of the deep rock mass, and realizing effective control of the surrounding rock of the deep buried tunnel.

Description

Technical Field

[0001] The present application relates to the technical field of tunnel surrounding rock stability control, and in particular to an excavation compensation method for a deep buried tunnel. Background Art

[0002] The Sichuan-Tibet region is located at the junction of the Eurasian Plate and the Indian Plate. The plate tectonic activity is extremely strong, resulting in the strong activity of the engineering rock mass in the Sichuan-Tibet region at a rate of tens of millimeters per year. The complex geological background determines that the deep rock mass in the Sichuan-Tibet region faces problems such as high ground stress, high seismic intensity, high environmental gradient, strong engineering disturbance, plate disturbance, and internal and external geological dynamic disturbance. Therefore, the complex geological environment makes the construction of tunnel projects in the Sichuan-Tibet region face many severe engineering problems such as large deformation of soft rocks, rock bursts, and crossing active fault zones.

[0003] In the "collapse arch" tunnel engineering design theory that has been used for more than a hundred years, the New Austrian Tunneling Method can give full play to the self-bearing capacity of the surrounding rock. Anchor rods and shotcrete are used as the main support means to control the deformation of the surrounding rock, and the deformation of the tunnel surrounding rock and support system is monitored and measured. The surrounding rock is regarded as an important part of the support system, and the design and construction of tunnels or underground projects are guided by the monitoring and measurement of the surrounding rock and support. The New Austrian Tunneling Method is aimed at the excavation of medium and shallow rocks. The surrounding rock has a certain self-stabilizing ability, and only the uniaxial strength of the surrounding rock is exerted. Its technical approach is "first give way and then resist". The key technology is the selection of the secondary optimal support time, and only low stress compensation is needed to achieve surrounding rock stability, so the support material can be achieved by using materials with small deformation.

[0004] However, at a deep depth, low stress compensation can no longer achieve surrounding rock stability, and the New Austrian Tunneling Method will fail. The tunnel surrounding rock produces the first excavation effect, the surrounding rock radial stress instantly becomes zero, the surrounding rock stress state changes from a triaxial stress state to a uniaxial stress state, and the surrounding rock bearing capacity is greatly reduced; as time goes by, the tunnel surrounding rock produces the second excavation effect, the tangential stress will be concentrated, exceeding the surrounding rock strength envelope, thus causing the surrounding rock to be damaged.

[0005] Therefore, the present application provides a deep tunnel excavation compensation method to solve the above technical problems. Summary of the invention

[0006] The purpose of this application is to provide a deep tunnel excavation compensation method that can solve at least one of the above-mentioned technical problems. The specific solution is as follows:

[0007] According to a specific implementation of the present application, the present application provides an excavation compensation method for a deep buried tunnel, comprising:

[0008] Obtain engineering geological information of deep buried tunnels;

[0009] Determining the type of engineering disaster based on the engineering geological information;

[0010] Determining an excavation compensation support strategy for the surrounding rock of the deep-buried tunnel based on the type of engineering disaster, wherein the excavation compensation support strategy can reduce the difference between the radial stress of the surrounding rock of the deep-buried tunnel and the original surrounding rock stress to within a preset approximate value range, and can effectively prevent the tangential stress from causing stress concentration;

[0011] Based on the excavation compensation support strategy, supplementary support control is performed on the surrounding rock of the deep tunnel.

[0012] Optionally, the determining of the excavation compensation support strategy of the surrounding rock of the deep tunnel based on the engineering disaster type includes:

[0013] When the engineering disaster type is characterized as a large deformation disaster type of soft rock exceeding the meter level, the excavation compensation support strategy is determined to be a high prestressed strong and tough anchor net combination strategy and a truss-type arch frame bearing strategy.

[0014] Optionally, determining the type of engineering disaster based on the engineering geological information includes:

[0015] When the high-stress hard rock stratum information is determined based on the engineering geological information, the engineering disaster type is determined to be a tunnel rock burst disaster type based on the high-stress hard rock stratum information.

[0016] Optionally, the determining of the excavation compensation support strategy of the surrounding rock of the deep tunnel based on the engineering disaster type includes:

[0017] When the engineering disaster type is characterized as a tunnel rock burst disaster type, the excavation compensation support strategy is determined to be a high prestressed strong and tough anchor net combination strategy and a concentrated energy directional blasting strategy.

[0018] Optionally, the determining of the excavation compensation support strategy of the surrounding rock of the deep tunnel based on the engineering disaster type includes:

[0019] When the engineering disaster type is characterized as an active fault type and / or a fault fracture zone type, the excavation compensation support strategy is determined to be a high prestressed strong and tough combined anchor net strategy, a truss-type arch bearing strategy and a graded grouting control strategy.

[0020] Optionally, the high prestressed strong and tough combined anchor net strategy includes:

[0021] Within a preset safety period after the deep tunnel is excavated, using the first support member to perform prestressed support compensation of a preset strength on the radial load of the surrounding rock clearance of the deep tunnel;

[0022] Using the second support member to disperse and transfer the radial load along the surface of the surrounding rock;

[0023] Precast concrete of a preset thickness is sprayed on the surface of the surrounding rock.

[0024] Optionally, the truss-type arch bearing strategy includes:

[0025] In the radial direction of the surrounding rock of the deep tunnel, the multi-layer steel arch frames are fixedly connected into a multi-layer composite steel arch frame by using I-beams of preset length as connecting pieces;

[0026] In the axial direction of the deep-buried tunnel, multiple multi-layer composite steel arch frames with preset interval lengths are fixedly connected using T-shaped steel, and the multi-layer composite steel arch frames are fixedly connected in an oblique herringbone shape using threaded steel with a preset diameter to form a truss-type arch frame.

[0027] Optionally, the focused energy directional blasting strategy includes:

[0028] In the deep buried tunnel construction, a plurality of directional energy tubes are buried in the rock mass within the preset excavation range, and the explosives in the directional energy tubes are detonated to generate high temperature and high pressure gas;

[0029] The gas is formed into a high-energy flow through a row of linearly distributed directional energy-gathering holes respectively arranged in at least one set direction in each energy-gathering directional tube, and acts on the corresponding hole wall outward to generate tensile stress, and the surrounding rock of the hole wall is stretched and cracked along the set direction through the tensile stress;

[0030] The superimposed stress field generated by each row of directional energy-gathering holes causes the rock mass within the preset excavation range to be directionally tensilely fractured, forming a directional blasting cutting surface.

[0031] Optionally, the graded grouting control strategy includes:

[0032] When constructing in the strata of active faults and / or fault fracture zones, at the face of the deep buried tunnel, a preset low grouting pressure is used to allow the conductive pressure of the coarse-grained cement slurry to overcome the initial ground stress of the strata and the tensile strength of the surrounding rock, thereby expanding the original pores and / or cracks in the strata;

[0033] A preset high grouting pressure is used to force fine-sized particles to expand into the pores and / or cracks, initiate and expand new cracks, and ultimately generate a grout-stopping wall of a preset thickness.

[0034] Optionally, after performing supplementary support control on the surrounding rock of the deep tunnel based on the excavation compensation support strategy, the method further includes:

[0035] Conduct real-time monitoring of deep buried tunnels after supplementary support control to obtain real-time monitoring data;

[0036] When the real-time monitoring data is abnormal, a new excavation compensation support strategy is determined based on the real-time monitoring data;

[0037] Based on the new excavation compensation support strategy, supplementary support control is performed on the surrounding rock of the deep buried tunnel.

[0038] Compared with the prior art, the above solution of the embodiment of the present application has at least the following beneficial effects:

[0039] The present application provides an excavation compensation method for a deep-buried tunnel. The method includes: obtaining engineering geological information of the deep-buried tunnel; determining the type of engineering disaster based on the engineering geological information; determining the excavation compensation support strategy of the surrounding rock of the deep-buried tunnel based on the type of engineering disaster; and performing supplementary support control on the surrounding rock of the deep-buried tunnel based on the excavation compensation support strategy. The supplementary support strategy can reduce the difference between the radial stress and the initial ground stress of the surrounding rock of the deep-buried tunnel to within a preset approximate value range, and further effectively prevent the tangential stress from causing stress concentration. After the excavation of the deep-buried tunnel, high prestressed excavation compensation support is applied in a timely manner to restore the three-dimensional initial stress state of the surrounding rock as much as possible, thereby improving the bearing capacity of the surrounding rock, fully mobilizing the strength of the deep rock mass, and achieving effective control of the surrounding rock of the deep-buried tunnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A Mohr circle diagram showing a deep tunnel excavation compensation method according to an embodiment of the present application;

[0041] Figure 2 A flow chart of a deep tunnel excavation compensation method according to an embodiment of the present application is shown;

[0042] Figure 3 A schematic diagram of the construction of a high prestressed and strong-tough combined anchor net strategy in a deep tunnel excavation compensation method according to an embodiment of the present application is shown;

[0043] Figure 4 A schematic diagram of an energy-gathering directional pipe in a deep tunnel excavation compensation method according to an embodiment of the present application is shown;

[0044] Figure 5 A lateral schematic diagram showing the excavation compensation construction of a deep-buried tunnel according to the excavation compensation method of a deep-buried tunnel according to an embodiment of the present application;

[0045] Figure 6 A radial schematic diagram of excavation compensation construction of a deep buried tunnel according to an embodiment of the present application and a method for excavation compensation of a deep buried tunnel according to an embodiment of the present application is shown;

[0046] Figure 7 A schematic diagram of the monitoring process after the excavation compensation method of a deep tunnel according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0048] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings, and "multiple" generally includes at least two.

[0049] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0050] It should be understood that although the terms first, second, third, etc. may be used to describe in the embodiments of the present application, these descriptions should not be limited to these terms. These terms are only used to distinguish the descriptions. For example, without departing from the scope of the embodiments of the present application, the first may also be referred to as the second, and similarly, the second may also be referred to as the first.

[0051] As used herein, the words "if" and "if" may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)", depending on the context.

[0052] It should also be noted that the term "includes", "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, so that a commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprising a ..." do not exclude the existence of other identical elements in the commodity or device including the elements.

[0053] It should be particularly noted that any symbols and / or numbers in the specification that are not marked in the accompanying drawings are not drawing marks.

[0054] The optional embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0055] As the depth of deep buried tunnels increases, practice has proved that the traditional New Austrian Tunneling Method (NATM) tunnel construction has become insufficient. All the damage to tunnel projects is caused by excavation. The rock mass is stable before tunnel excavation, and after the project excavation, the rock mass will produce excavation effects.

[0056] like Figure 1 As shown, is the uniaxial tensile strength, For cohesion, is the tangential stress, is the axial stress, is the radial stress, is the tangential stress after compensation, After the deep tunnel is excavated, the tunnel surrounding rock produces the first excavation effect, and the radial stress of the surrounding rock The instantaneous loss is zero, the surrounding rock stress state changes from a triaxial stress state to a uniaxial stress state, and the surrounding rock bearing capacity is greatly reduced; as time goes by, the surrounding rock of the deep buried tunnel produces a second excavation effect, and the tangential stress Concentration will occur, under hydrostatic pressure conditions, tangential stress It will increase to two times, exceeding the Mohr-Coulomb envelope of the surrounding rock strength, causing the surrounding rock to be destroyed and produce a large deformation catastrophe, and the rock mass stress state will be transformed from a three-dimensional stress state to a two-dimensional or one-dimensional stress state.

[0057] To this end, the present application proposes a compensation method for solving the above-mentioned problem, that is, an embodiment of a deep tunnel excavation compensation method provided by the present application.

[0058] Combine the following Figure 2 The embodiments of the present application are described in detail.

[0059] Step S101, obtaining engineering geological information of a deep buried tunnel.

[0060] When the underground tunnel is buried more than a kilometer deep, it is called a deep tunnel. The rock mass of a deep tunnel is in a special and complex environment of high geostress, high geotemperature, high osmotic pressure and engineering disturbance, and nonlinear mechanical behaviors such as internal rupture of the surrounding rock, structural changes, energy accumulation and release, surrounding rock degradation, expansion and prominent rheological effects occur.

[0061] Engineering geological information, including: geological structure information, hydrogeological information, surrounding rock lithology information and physical and mechanical properties information and / or surrounding rock integrity.

[0062] For deep buried tunnels in complex geological environments, firstly, the reasonable tunnel excavation method (such as drilling and blasting method or tunnel boring machine) is determined through engineering geological information, the disturbance load of tunnel excavation is estimated, and the range of the loosening circle of the surrounding rock is theoretically analyzed and measured. According to the theoretical calculation of the above engineering geological analysis, the theoretical value of the excavation compensation support force is obtained to determine the excavation compensation support strategy of the deep buried tunnel. Then, the deformation of the surrounding rock during the excavation process is monitored in real time, including: grouting pressure, grouting amount, surrounding rock deformation data after support, anchor prestress / cable prestress, anchor pull-out force / cable pull-out force, anchor deformation data / cable deformation data, loosening circle data after support, structural stress after support and / or tunnel environment data. Through real-time monitoring data, the excavation compensation support strategy of the surrounding rock of the deep buried tunnel is continuously optimized to ensure the stability of the surrounding rock of the deep buried tunnel after construction.

[0063] Step S102: determining the type of engineering disaster based on the engineering geological information.

[0064] Engineering disaster types include: ultra-meter-scale soft rock large deformation disaster type, tunnel rock burst disaster type, and active fault type and / or fault fracture zone type.

[0065] The disturbance load of deep tunnel excavation can be estimated through engineering geological information. Through theoretical analysis and actual measurement, the scope of the surrounding rock loosening zone after construction can be determined and engineering disaster information can be obtained.

[0066] In some specific embodiments, determining the type of engineering disaster based on the engineering geological information includes:

[0067] Step S102a, when the high-stress hard rock stratum information is determined based on the engineering geological information, the engineering disaster information is determined to be tunnel rock burst disaster information based on the high-stress hard rock stratum information.

[0068] Tunnel rockburst disasters usually occur in hard rock strata with high geostress. Two effects are produced after the surrounding rock is excavated: the first excavation effect and the second excavation effect.

[0069] The first excavation effect refers to the rapid reduction of radial stress to zero within a preset instantaneous time period.

[0070] The second excavation effect refers to the rapid and concentrated increase of tangential stress within a preset time period to exceed a preset stress value threshold. For example, the preset stress value threshold is twice the original rock stress value.

[0071] Step S103, determining an excavation compensation support strategy for the surrounding rock of the deep tunnel based on the type of engineering disaster.

[0072] Among them, the excavation compensation support strategy can reduce the difference between the radial stress of the surrounding rock of the deep-buried tunnel and the original surrounding rock stress to within a preset approximate value range, and can effectively prevent the stress concentration phenomenon of the tangential stress.

[0073] For example, the preset approximate value range includes: 0 to 30% of the radial stress of the surrounding rock of the deep buried tunnel. For example, the difference is reduced to 0, or the difference is reduced to 5% of the radial stress of the surrounding rock of the deep buried tunnel, or the difference is reduced to 10% of the radial stress of the surrounding rock of the deep buried tunnel, or the difference is reduced to 20% of the radial stress of the surrounding rock of the deep buried tunnel, or the difference is reduced to 10% of the radial stress of the surrounding rock of the deep buried tunnel.

[0074] In some specific embodiments, the determining of the excavation compensation support strategy of the surrounding rock of the deep tunnel based on the engineering disaster type includes:

[0075] Step S103a, when the engineering disaster type is characterized as a large deformation disaster type of soft rock exceeding the meter level, determining the excavation compensation support strategy as a high prestressed strong and tough anchor net combination strategy and a truss arch bearing strategy.

[0076] In deep tunnel projects, traditional countermeasures such as increasing the reserved deformation, double-layer steel arch support, and increasing the concrete thickness of the secondary lining are difficult to effectively prevent and control large deformation disasters of soft rocks exceeding the meter level. Figure 5 and Figure 6 shown.

[0077] To this end, this specific embodiment provides a high prestressed strong and tough combined anchor net strategy and a truss-type arch frame bearing strategy.

[0078] In some specific embodiments, the high prestressed strong and tough combined anchor net strategy includes:

[0079] The first step is to use a first supporting member to perform prestressed support compensation of a preset strength on the radial load of the surrounding rock clearance of the deep tunnel within a preset safety time period after the deep tunnel is excavated.

[0080] The high prestressed strong and tough combined anchor net strategy needs to support the surrounding rock in a short period of time. For example, the preset safe time period is half an hour.

[0081] The first support component includes micro NPR anchor rods and / or micro NPR anchor cables, NPR anchors, NPR anchor pads and high-performance durable resin anchoring agents made of high-strength and high-toughness NPR new steel, such as Figure 5 and Figure 6 shown.

[0082] Deep in the surrounding rock, the durable resin anchor tightly bonds the micro NPR anchor rod or micro NPR anchor cable to the deep surrounding rock; on the surface of the surrounding rock, the NPR anchor and NPR anchor pad work together to lock the micro NPR anchor rod or micro NPR anchor cable.

[0083] In the second step, the radial load is dispersed and transmitted along the surface of the surrounding rock by using the second supporting member.

[0084] The second supporting component includes NPR steel mesh, NPR corrugated steel guard plate and NPR steel fiber concrete made of high-strength and high-toughness NPR new steel.

[0085] NPR steel wire mesh, NPR corrugated steel guard plate and NPR steel fiber concrete mainly disperse and transmit radial load along the surface of surrounding rock. NPR steel wire mesh is laid close to the surface of surrounding rock; the end of micro NPR anchor rod or micro NPR anchor cable passes through the through hole of NPR corrugated steel guard plate and is locked by NPR anchor and NPR anchor pad.

[0086] The third step is to spray precast concrete of a preset thickness on the surface of the surrounding rock.

[0087] The preset thickness includes 10 to 20 cm, which is determined specifically by the degree of crushing of the surrounding rock.

[0088] Precast concrete, including NPR steel fiber reinforced concrete.

[0089] like Figure 3 As shown in the figure, during construction, along the surface of the deep tunnel surrounding rock, from shallow to deep, it is divided into the following three layers: the first layer is the NPR steel fiber concrete spray layer; the second layer is the NPR anchor and NPR anchor pad pressing the NPR corrugated steel guard plate and NPR wire mesh, all of which have through holes, connected by micro NPR anchor rods or micro NPR anchor cables; the third layer is the anchor end of the micro NPR anchor rod or micro NPR anchor cable and the deep surrounding rock bonded by a durable resin anchor. A "point-line-surface" high prestressed NPR anchor mesh layer with micro NPR anchor rods or micro NPR anchor cables as the main body is formed, such as Figure 6 shown.

[0090] Specifically, the high prestressed strong and tough combined anchor net strategy applies pre-tightening force to the micro NPR anchor rod or micro NPR anchor cable through reverse tensioning by tensioning jacks, and timely conducts the excavation surrounding rock. Figure 1 The high prestress compensation shown in the figure can reduce or control the risk of surrounding rock crushing and instability. The high prestressed strong and tough combined anchor net strategy can lock the prestress in time by quickly applying prestress to the surrounding rock.

[0091] In some specific embodiments, the truss-type arch bearing strategy includes:

[0092] In the first step, in the radial direction of the surrounding rock of the deep-buried tunnel, single-layer steel frames are fixedly connected into multi-layer steel frames using I-beams of preset length.

[0093] In the second step, in the axial direction of the surrounding rock of the deep buried tunnel, multiple multi-layer steel frames with preset interval lengths are fixedly connected by using T-shaped steel, and multiple multi-layer steel frames are fixedly connected in an oblique herringbone shape by using threaded steel with preset diameters to form a truss-type arch frame, such as Figure 5 and Figure 6 shown.

[0094] Common arch frames commonly used in deep buried tunnels are usually made of single-layer I-beams and steel sections. Due to the deformation and compression of the surrounding rock, the damage to the arch frames is mainly stiffness damage such as bending deformation and twisting deformation, as well as strength damage such as shear damage and tension damage. The fundamental reason is that the arch frame itself has low structural stiffness and poor integrity, and the connection between the arch frames is relatively weak.

[0095] As a heavy-duty steel, I-beams have the advantage of high material strength, strong tensile, compressive and shear resistance. The truss arch bearing strategy gives full play to its advantages through mechanical design and improves its ability to resist deformation, distortion and shear. During large deformation of the surrounding rock, the truss arch relies on its excellent bearing characteristics and can maintain the stability of the overall structure during the interaction with the surrounding rock.

[0096] The truss arch is an integral structural support member, which uses short I-beams (for example, the preset length includes 10-15 cm) as connectors in the radial direction of the deep-buried tunnel to connect single-layer steel frames into multi-layer steel frames (for example, multi-layer steel frames include double-layer steel frames).

[0097] In the axial connection of the deep-buried tunnel, multiple multi-layer steel frames with a preset interval length (for example, a preset interval length of 100 cm) are fixedly connected by welding using T-shaped steel, and the multiple multi-layer steel frames are fixedly connected in an oblique herringbone shape using threaded steel with a preset diameter (for example, a diameter of 22 mm) to improve the deformation stiffness of the truss-type arch frame.

[0098] The main advantage of the truss arch is that the bending and torsion resistance of the steel frame is converted into tensile, compressive or shearing performance through structural optimization design. The transverse connection of the truss arch is used to balance the uneven load of the longitudinal surrounding rock of the deep buried tunnel, so that the load acts relatively evenly on the entire truss; the main function of the radial connection between the truss arches is to transfer the unbalanced force from the radial direction of the tunnel, and finally make the overall force of the truss arch uniform, thereby improving the bearing capacity of the truss arch.

[0099] In terms of bending resistance, due to the strengthened radial connection of the truss-type arch frame, the bending moment mechanical properties of the truss-type arch frame are still greater than those of the single-layer arch frame. That is, under the same load, the single-layer arch frame is subjected to a greater bending moment and is most susceptible to damage.

[0100] In terms of shear resistance, the main point of failure of the truss arch is the radial stress point of the arch, that is, the failure of the steel arch is mainly shear failure. Since the truss arch has a certain connection with the multi-layer arch in the radial direction, the shear resistance of the truss arch is several times that of the single-layer arch. For example, the shear resistance of the double-layer arch is 1.6 times that of the single-layer arch.

[0101] On the torsion-resistant surface, the longitudinal and transverse connections of the truss-type arch frame improve the integrity and rigidity of its overall structure. Therefore, under the same load, the torque of the truss-type arch frame is the smallest. The torque resistance of the truss-type arch frame is several times that of the single-layer arch frame. For example, the torque resistance of the double-layer arch frame is 2.65 times that of the single-layer arch frame.

[0102] In this specific embodiment, when the engineering disaster information is characterized as large deformation disaster information of soft rock exceeding the meter level, the excavation compensation support strategy is determined to be a high prestressed strong and tough combined anchor net strategy and a truss-type arch bearing strategy.

[0103] First, in view of the characteristics of deep-buried tunnel soft rock with large deformation loosening zone, large deformation and fast deformation rate, a high prestressed and strong-tough combined anchor net strategy is provided. The purpose is to fully mobilize the bearing characteristics of the surrounding rock of deep-buried tunnels by using micro-NPR anchor rods or micro-NPR anchor cables, connect the shallow loose surrounding rock in series by using micro-NPR anchor rods or micro-NPR anchor cables, apply preset prestress (for example, the preset prestress is 30 t) to the micro-NPR anchor rods or micro-NPR anchor cables, increase the friction between the surrounding rock of the shallow loosening zone, connect the shallow surrounding rock with the deep surrounding rock through the micro-NPR anchor rods or micro-NPR anchor cables, and form a stable connection. Based on the high prestressed and strong-tough combined anchor net strategy, the prestress is quickly applied and the prestress is locked in time, which can effectively reduce the deformation rate and deformation magnitude of soft rock.

[0104] Deep buried tunnels are often affected by tectonic stress and are prone to asymmetric large deformation. The truss-type arch bearing strategy makes full use of the advantages of I-beams and gives full play to their advantages through mechanical design to enhance their ability to resist deformation, twisting and shearing. The lateral connection of the truss-type arch is mainly used to balance the uneven load of the tunnel's longitudinal surrounding rock, so that the load acts relatively evenly on the entire arch. The main function of the radial connection between truss-type arches is to transmit the unbalanced force from the radial direction of the tunnel, and ultimately make the overall force of the arch uniform, thereby improving the bearing capacity of the truss-type arch. Thereby ensuring that the stability of the overall structure of the truss-type arch is maintained during its interaction with the surrounding rock. The truss-type arch bearing strategy can replace the commonly used double-layer steel arch support strategy.

[0105] In some specific embodiments, the determining of the excavation compensation support strategy of the surrounding rock of the deep tunnel based on the engineering disaster type includes:

[0106] Step S103b: when the engineering disaster type is characterized as a tunnel rock burst disaster type, determining the excavation compensation support strategy to be a high prestressed strong and tough anchor net combination strategy and a concentrated energy directional blasting strategy.

[0107] When the engineering disaster information is characterized as tunnel rockburst disaster information, the first excavation effect and the second excavation effect are generated after the surrounding rock is excavated. To this end, a high prestressed strong and tough combined anchor net strategy is used to deal with the first excavation effect, and a concentrated energy directional blasting strategy is used to deal with the second excavation effect.

[0108] In some specific embodiments, the focused energy directional blasting strategy includes:

[0109] The first step is to detonate explosives in a plurality of energy-focused directional tubes buried in the rock mass within a preset excavation range to generate high-temperature, high-pressure gas during the deep tunnel construction.

[0110] In the second step, the gas is formed into a high-energy flow through a row of linearly distributed directional energy-focusing holes respectively arranged in at least one set direction of each energy-focusing directional tube, and acts outwardly on the corresponding hole wall to generate tensile stress, and the hole wall is stretched and cracked along the set direction through the tensile stress.

[0111] The third step is to use the superimposed stress field generated by each row of directional energy-gathering holes to cause the rock mass within the preset excavation range to undergo directional tensile fracture and form a directional blasting cutting surface.

[0112] The energy-gathering directional tube includes: a tube body, directional energy-gathering holes, a charge roll, a detonator, a gun mud and a booster tube. Figure 4 As shown, at least one row of linearly distributed directional energy-gathering holes is arranged on the tube body. Powder rolls, detonators, gun mud and booster tubes are arranged in the tube body.

[0113] The directional blasting strategy takes advantage of the rock's characteristics of resistance to compression and fear of tension. When the explosives (charge rolls, detonators, gun mud and booster tubes) in the directional directional tube are detonated, they will react and release a large amount of high-temperature and high-pressure gas in a very short time (such as 0.05s to 0.5s). The directional tube has an instantaneous suppression effect on the gas, and the directional directional hole provides it with an instantaneous pressure relief space first, forming a high-energy flow at the directional directional hole, which acts on the corresponding hole wall and generates radial initial cracks; the subsequent high-temperature and high-pressure gas is still released from the directional directional hole, driving the radial initial cracks, forming a strong "gas wedge" in it, causing the cracks to become unstable, generating tensile stress concentration in the set direction, accelerating the directional expansion of the cracks, and resulting in the tension and cracking of the rock mass in the set direction. At the same time, due to the suppression and buffering effect of the directional tube body, the stress acting on the hole wall in the non-set direction is greatly reduced, which plays a certain protective role on the rock mass in the non-set direction.

[0114] When multiple directional energy-gathering holes are blasted at the same time, a superimposed stress field will be generated between the holes, and the tensile stress between the directional energy-gathering holes will increase; if the spacing between the directional energy-gathering holes is appropriate, the cracks between adjacent holes can be connected to form a directional single crack surface. The essence of the energy-gathering directional blasting strategy is to use the energy-gathering directional tube to make the blasting products produce uniform pressure in the non-set direction of the hole wall, and produce concentrated tension in the set direction, and use the characteristics of rock resistance to compression and fear of tension to form directional tensile fractures in the rock mass.

[0115] The energy-focused directional blasting strategy can achieve directional blasting, reduce tunnel over-excavation, reduce damage to surrounding rocks, and avoid the expansion of the loose zone due to blasting and excavation, which may lead to instability of surrounding rocks.

[0116] In order to reduce the concentration of tangential stress in the surrounding rock of a deep tunnel after excavation, this specific embodiment uses an energy-focusing directional tube to convert the high-temperature and high-pressure airflow generated by the explosion of explosives into a point-shaped energy jet through a directional energy-focusing hole. The energy jet will concentrate the tensile stress on the local area of ​​the directional energy-focusing hole, protect other areas from being evenly compressed, and cause directional cracks in the rock that is resistant to compression but not to tension.

[0117] The energy-gathering directional blasting strategy is adopted to carry out multi-hole blasting in the rock mass. In the rock mass, a connected directional crack is generated along the set direction of the directional energy-gathering hole, thereby forming a directional blasting, reducing damage to the surrounding rock, avoiding the expansion of the loose circle caused by blasting excavation, and affecting the stability of the surrounding rock. The energy-gathering directional blasting strategy can accurately excavate the face of the deep-buried tunnel, ensure the roundness of the surrounding rock after tunnel excavation, reduce the surface roughness of the hard rock tunnel, and reduce the rock burst disaster caused by local stress concentration.

[0118] In some specific embodiments, the determining of the excavation compensation support strategy of the surrounding rock of the deep tunnel based on the engineering disaster type includes:

[0119] Step S103c, when the engineering disaster information is characterized as an active fault type and / or a fault fracture zone type, the excavation compensation support strategy is determined to be a high prestressed strong and tough combined anchor net strategy, a truss arch bearing strategy and a graded grouting control strategy.

[0120] In some specific embodiments, Figure 5 and Figure 6 As shown, the graded grouting control strategy includes:

[0121] The first step is to use a preset low grouting pressure at the face of the deep tunnel during construction in the strata of active faults and / or fault fracture zones so that the conductive pressure of the coarse-grained cement slurry overcomes the initial ground stress of the strata and the tensile strength of the surrounding rock, thereby expanding the original pores and / or cracks in the strata, or forming new cracks and / or pores;

[0122] In the second step, a preset high grouting pressure is used to force fine-sized particles to expand into the pores and / or cracks, initiate and expand new cracks, and ultimately generate a grout-stopping wall of a preset thickness.

[0123] The graded grouting control strategy is an advanced support technology proposed for deep tunnels passing through active faults and / or fault fracture zones, which may cause large deformation disasters of surrounding rocks or sudden mud and water gushing disasters in deep tunnels.

[0124] The face, also known as the face of the tunnel, is a term used in tunnel construction, which refers to the working face that is constantly advancing in tunnel excavation (coal mining, mining or tunnel engineering).

[0125] The graded grouting control strategy is used to prevent the penetration of fissure water in active faults and / or fault fracture zones, fundamentally changing the deep fractured and broken rock structure of deep buried tunnels and improving the surrounding rock strength.

[0126] The preset thickness includes 2 to 2.5 m, and the diameters of the grouting pipes for coarse particles and fine particles are both 60 mm.

[0127] The coarse-grained cement slurry is early-strength sulphoaluminate single-liquid slurry + HPC grouting admixture, with a particle size of about 20μm, a preset low grouting pressure of 2 to 3MPa, and a grouting flow rate of about 30L / min.

[0128] Fine-grained cement slurry is ultrafine cement with a particle size of about 2 μm. The preset high grouting pressure includes 8 to 10 MPa, and the grouting flow rate includes about 20 L / min.

[0129] After the grouting is completed, it needs to be cured for 3 days to wait for the grouting liquid to fully solidify.

[0130] The graded grouting layer is generated by the graded grouting control strategy, such as Figure 5 and Figure 6 As shown in the figure, the voids in the surrounding rock of the deep-buried tunnel are filled, the friction angle and cohesion in the rock mass are increased, and the properties of the surrounding rock are improved; and the slurry can squeeze out the air and moisture in the voids, resist the penetration of external moisture, significantly improve the impermeability of the surrounding rock, form a complete slurry vein network and a stable slurry vein skeleton, improve the microstructure of the surrounding rock, enhance the integrity of the surrounding rock, and provide a stable anchoring point for the micro-NPR anchor rod or micro-NPR anchor cable, which is conducive to the subsequent micro-NPR anchor rod or micro-NPR anchor cable to fully exert its performance.

[0131] Step S104: performing supplementary support control on the surrounding rock of the deep tunnel based on the excavation compensation support strategy.

[0132] The embodiment of the present application obtains engineering geological information of a deep-buried tunnel; determines the type of engineering disaster based on the engineering geological information; determines the excavation compensation support strategy of the surrounding rock of the deep-buried tunnel based on the type of engineering disaster; and performs supplementary support control on the surrounding rock of the deep-buried tunnel based on the excavation compensation support strategy. The supplementary support strategy can reduce the difference between the radial stress and the initial ground stress of the surrounding rock of the deep-buried tunnel to within a preset approximate value range, and further can effectively prevent the stress concentration phenomenon of the tangential stress. After the excavation of the deep-buried tunnel, high prestressed excavation compensation support is applied in time to restore the three-dimensional initial stress state of the surrounding rock as much as possible, thereby improving the bearing capacity of the surrounding rock, fully mobilizing the strength of the deep rock mass, and achieving effective control of the surrounding rock of the deep-buried tunnel.

[0133] In some specific embodiments, Figure 7 As shown, after the supplementary support control of the surrounding rock of the deep buried tunnel based on the excavation compensation support strategy is performed, the following steps are also included:

[0134] Step S110 - 1 , real-time monitoring of the surrounding rock of the deep buried tunnel after supplementary support control is performed to obtain real-time monitoring data.

[0135] Real-time monitoring data, including: grouting pressure, grouting volume, surrounding rock deformation data after support, anchor prestress / cable prestress, anchor pull-out force / cable pull-out force, anchor deformation data / cable deformation data, loose circle data after support, structural stress after support and / or tunnel environment data.

[0136] Step S110-2: when the real-time monitoring data is abnormal, determine a new excavation compensation support strategy based on the real-time monitoring data.

[0137] Step S110-3: performing supplementary support control on the surrounding rock of the deep tunnel based on the new excavation compensation support strategy.

[0138] like Figure 7As shown, this specific embodiment determines the excavation compensation support strategy of the deep-buried tunnel surrounding rock based on the engineering geological information, and then performs construction based on the excavation compensation support strategy. During the construction project, the deep-buried tunnel surrounding rock is continuously monitored in real time, and the excavation compensation support strategy of the deep-buried tunnel surrounding rock is continuously optimized through real-time monitoring data to ensure the stability of the deep-buried tunnel surrounding rock after construction.

[0139] Finally, it should be noted that: the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0140] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application 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 make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for compensating for excavation of a deep tunnel, characterized in that: include: Obtain engineering geological information of deep buried tunnels; Determining the type of engineering disaster based on the engineering geological information; Determining an excavation compensation support strategy for the surrounding rock of the deep-buried tunnel based on the type of engineering disaster, wherein the excavation compensation support strategy can reduce the difference between the radial stress of the surrounding rock of the deep-buried tunnel and the original surrounding rock stress to within a preset approximate value range, and can effectively prevent the tangential stress from causing stress concentration; Based on the excavation compensation support strategy, supplementary support control is performed on the surrounding rock of the deep tunnel.

2. The method according to claim 1, characterized in that The excavation compensation support strategy of the surrounding rock of the deep tunnel is determined based on the type of engineering disaster, including: When the engineering disaster type is characterized as a large deformation disaster type of soft rock exceeding the meter level, the excavation compensation support strategy is determined to be a high prestressed strong and tough anchor net combination strategy and a truss-type arch frame bearing strategy.

3. The method according to claim 1, characterized in that Determining the type of engineering disaster based on the engineering geological information includes: When the high-stress hard rock stratum information is determined based on the engineering geological information, the engineering disaster type is determined to be a tunnel rock burst disaster type based on the high-stress hard rock stratum information.

4. The method according to claim 3, characterized in that The excavation compensation support strategy of the surrounding rock of the deep tunnel is determined based on the type of engineering disaster, including: When the engineering disaster type is characterized as a tunnel rock burst disaster type, the excavation compensation support strategy is determined to be a high prestressed strong and tough anchor net combination strategy and a concentrated energy directional blasting strategy.

5. The method according to claim 1, characterized in that The excavation compensation support strategy of the surrounding rock of the deep tunnel is determined based on the type of engineering disaster, including: When the engineering disaster type is characterized as an active fault type and / or a fault fracture zone type, the excavation compensation support strategy is determined to be a high prestressed strong and tough combined anchor net strategy, a truss-type arch bearing strategy and a graded grouting control strategy.

6. The method according to claim 2, 4 or 5, characterized in that: The high prestressed strong and tough combined anchor net strategy includes: Within a preset safety period after the deep tunnel is excavated, using the first support member to perform prestressed support compensation of a preset strength on the radial load of the surrounding rock clearance of the deep tunnel; Using the second support member to disperse and transfer the radial load along the surface of the surrounding rock; Precast concrete of a preset thickness is sprayed on the surface of the surrounding rock.

7. The method according to claim 2 or 5, characterized in that: The truss arch bearing strategy includes: In the radial direction of the surrounding rock of the deep tunnel, the multi-layer steel arch frames are fixedly connected into a multi-layer composite steel arch frame by using I-beams of preset length as connecting pieces; In the axial direction of the deep-buried tunnel, multiple multi-layer composite steel arch frames with preset interval lengths are fixedly connected using T-shaped steel, and the multi-layer composite steel arch frames are fixedly connected in an oblique herringbone shape using threaded steel with a preset diameter to form a truss-type arch frame.

8. The method according to claim 4, characterized in that The energy-focused directional blasting strategy includes: In the deep buried tunnel construction, a plurality of directional energy tubes are buried in the rock mass within the preset excavation range, and the explosives in the directional energy tubes are detonated to generate high temperature and high pressure gas; The gas is formed into a high-energy flow through a row of linearly distributed directional energy-gathering holes respectively arranged in at least one set direction in each energy-gathering directional tube, and acts on the corresponding hole wall outward to generate tensile stress, and the surrounding rock of the hole wall is stretched and cracked along the set direction through the tensile stress; The superimposed stress field generated by each row of directional energy-gathering holes causes the rock mass within the preset excavation range to be directionally tensilely fractured, forming a directional blasting cutting surface.

9. The method according to claim 5, characterized in that The graded grouting control strategy includes: When constructing in the strata of active faults and / or fault fracture zones, at the face of the deep buried tunnel, a preset low grouting pressure is used to allow the conductive pressure of the coarse-grained cement slurry to overcome the initial ground stress of the strata and the tensile strength of the surrounding rock, thereby expanding the original pores and / or cracks in the strata; A preset high grouting pressure is used to force fine-sized particles to expand into the pores and / or cracks, initiate and expand new cracks, and ultimately generate a grout-stopping wall of a preset thickness.

10. The method according to claim 1, characterized in that After the supplementary support control of the surrounding rock of the deep tunnel based on the excavation compensation support strategy is performed, the method further includes: Conduct real-time monitoring of deep buried tunnels after supplementary support control to obtain real-time monitoring data; When the real-time monitoring data is abnormal, a new excavation compensation support strategy is determined based on the real-time monitoring data; Based on the new excavation compensation support strategy, supplementary support control is performed on the surrounding rock of the deep buried tunnel.

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