Water-inrush and mud-inrush high ground stress soft rock tunnel supporting structure and method

Abstract

The invention provides a water inrush and mud inrush high ground stress soft rock tunnel supporting structure and method.The water inrush and mud inrush high ground stress soft rock tunnel supporting structure comprises a reinforcing water plugging layer which is composed of an outer layer tunnel surrounding rock, a plurality of rod body sections dispersed in the outer layer tunnel surrounding rock and a grouting body injected into the outer layer tunnel surrounding rock, an original rock mass is arranged outside the periphery; the compaction and drainage layer is located on the inner side of the reinforcing water plugging layer and composed of inner-layer tunnel surrounding rock, a plurality of functional sections dispersed in the inner-layer tunnel surrounding rock and a grouting body injected into the inner-layer tunnel surrounding rock, the periphery of the compaction and drainage layer makes contact with the reinforcing water plugging layer, and the compaction and drainage layer has the compaction and drainage functions. The method has the beneficial effects that the safety and the stability of the tunnel structure can be kept in construction and later operation, and water inrush, mud inrush, soft rock large-deformation support, lining deformation and cracking and other diseases can be controlled and prevented.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel construction, and in particular to a support structure and method for a soft rock tunnel with high ground stress and sudden water and mud. Background Art

[0002] Soft rock is a complex rock mechanical medium with significant plastic deformation under specific conditions; high geostress soft rock tunnels are usually located in areas with complex geological conditions and large geostress. Due to the complex combined effects of high stress, softened (melted) rock and high water pressure, high geostress soft rock water and mud burst tunnels cause multiple tunnel structures to have various disease problems in different stages of construction and operation. In general, the diseases can be divided into two categories: material migration diseases (water burst, mud burst, seepage) and structural overload deformation diseases (large deformation, cracking).

[0003] Water and mud suddenness refers to the sudden occurrence of disasters such as water gushing and mud-rock flow during tunnel construction, which are usually accompanied by major geological changes and construction risks. They are characterized by suddenness, unpredictability and severity of disasters, and often have a serious impact on construction safety and project quality.

[0004] Therefore, how to maintain the safety and stability of the tunnel structure during construction and later operation; how to control and prevent diseases such as water inrush, mud inrush, large deformation support of soft rock, and lining deformation and cracking have become important issues in the construction of high-stress soft rock tunnels. Summary of the invention

[0005] The purpose of the present invention is to solve at least one of the above-mentioned deficiencies in the prior art. For example, the present invention also proposes a support structure and method for a soft rock tunnel with high ground stress and water and mud inrush. By setting a compacted water-repellent layer and a reinforced water-blocking layer, the inner ring layer is constructed into a "compacted water-repellent zone" and the outer ring layer is constructed into a "reinforced water-blocking zone" to form a "far defense and near drainage". In addition, the lining and anchor rods in the support structure simultaneously exert a bidirectional squeezing effect on the rock mass - the initial lining generates a support pressure p on the inner wall of the tunnel surrounding rock. r When the anchor bolt is stretched, it expands and deforms, squeezing the surrounding rock in the tangential direction, generating a tangential support force p τ , so that the tangential stress σ θ Under the action of enlargement, the inner layer forms a compaction effect; the inner layer forms an internal "pressure arch" in stress-deformation, which has a certain bearing capacity and can provide radial bearing stress to the outer layer rock; at the same time, this compaction effect cooperates with the hydrophobic structure, based on the principle of regionalized regulation of groundwater migration and surrounding rock stress state in space, can further reduce the water content of the inner layer rock, reduce water inrush, mud inrush and large deformation of the rock.

[0006] One aspect of the present invention provides a support structure for a soft rock tunnel with high ground stress and water and mud inrush. The support structure for a soft rock tunnel with high ground stress and water and mud inrush is to plan the surrounding rock of the tunnel into a compacted water-draining layer and a reinforced water-blocking layer according to its function through engineering measures, wherein: the reinforced water-blocking layer is composed of an outer layer of tunnel surrounding rock, a plurality of rod segments dispersed in the outer layer of tunnel surrounding rock, and a grouting body injected into the outer layer of tunnel surrounding rock, and has the function of bearing the pressure of the outer surrounding rock and the pressure of the original rock groundwater to block water, and the original rock mass is outside its perimeter; the compacted water-draining layer is located inside the reinforced water-blocking layer, and is composed of an inner layer of tunnel surrounding rock, a plurality of functional segments dispersed in the inner layer of tunnel surrounding rock, and a grouting body injected into the inner layer of tunnel surrounding rock, and its periphery is in contact with the reinforced water-blocking layer, and has the function of providing a supporting reaction force to the reinforced water-blocking layer to improve the stress state of the reinforced water-blocking layer, and at the same time, the inner layer of tunnel surrounding rock cooperates with the functional segments to enable it to have the functions of compaction and drainage;

[0007] Among them, the functional section and the rod body section are connected one by one to form an integral anchor structure. The functional section penetrates the compacted hydrophobic layer along the tunnel radial direction. The functional section has drainage and expansion deformation functions. A drainage outlet is provided at the rear end of the functional section. At the same time, an anchor head of the anchor structure is provided at the rear end of the functional section. The anchor head acts on the tunnel rock wall through the tray, and forms a primary support structure with the composite support material steel mesh, steel frame and shotcrete outside the tunnel rock wall.

[0008] In this scheme, the reinforced water blocking layer, compacted water-draining layer and primary support structure of the tunnel surrounding rock cooperate with each other in the stress field and seepage field to form the following mechanism:

[0009] The primary support structure forms a compaction and large deformation support effect on the compacted water-repellent layer, improves the stress state of the surrounding rock in the compacted water-repellent layer, forms a pressure arch structure in the inner circle, and provides a certain bearing capacity of the surrounding rock, so that the compacted water-repellent circle can provide a supporting reaction force to the external reinforced water-blocking layer;

[0010] After reinforcement and improvement of stress state, the reinforced water-blocking layer ensures the stability of the surrounding rock mass, so that the bearing capacity of the surrounding rock mass can be fully exerted; after the reinforced water-blocking layer is plugged by grouting, the permeability is reduced, the seepage volume of groundwater to the internal compacted hydrophobic layer is controlled, and at the same time, most of the pore water pressure is borne; under the action of compaction and drainage, the compacted hydrophobic layer promotes the discharge of a small amount of infiltrated pore water, reduces the water content and water pressure in the rock mass, thereby reducing the softening effect of water on the rock mass, and then improves the mechanical strength of the surrounding rock mass, which helps to improve the structural stability.

[0011] In a preferred embodiment of the present scheme, the front section of the rod body segment is connected to the reinforced water blocking layer as an anchoring section for anchoring (the anchoring section and the reinforced water blocking layer are combined to form a reinforced water blocking effect), the rear section of the rod body segment is a free section connected to a functional section (having compaction and drainage functions), and the functional section is located in the compaction hydrophobic layer to achieve drainage of the compaction hydrophobic layer.

[0012] The anchor head includes traditional components such as threads, nuts, trays, etc., which are convenient for forming primary support.

[0013] In a preferred embodiment of the present scheme, the functional section includes a sleeve and a pull rod, the front end of the sleeve is connected to the rear end of the rod section; the pull rod is sleeved in the sleeve, and the rear end thereof passes through the rear end opening of the sleeve; the pull rod can be relatively displaced relative to the sleeve, so that the functional section can be stretched and deformed along the axial direction of its anchor rod, and at the same time squeeze the inner wall of the sleeve to cause the sleeve to expand and deform; and when the sleeve expands and deforms, the sleeve squeezes the surrounding rock of the tunnel in the tangential direction of the tunnel to generate a tangential compression force p τ The anchor head is arranged at the rear end of the tie rod, and after the functional section penetrates the compacted hydrophobic layer along the tunnel radial direction, it is connected to the tray through the anchor head on the tie rod.

[0014] When the sleeve of the functional section is stretched and deformed along the axial direction of the anchor rod, it can continue to apply anchoring force to the rock mass without failure.

[0015] In a preferred embodiment of the present scheme, a plurality of water-permeable deformation joints are provided on the sleeve, the pull rod is a hollow pull rod, and a plurality of small holes are provided on the pull rod. The pore water in the rock mass of the compacted hydrophobic layer can enter the sleeve along the water-permeable deformation joints and then enter the pull rod through the small holes, and finally be discharged from the rock mass through the drainage port at the rear end of the pull rod.

[0016] In a preferred embodiment of the present scheme, the support structure for high-stress soft rock tunnel with sudden water and mud also includes a drainage pipe. The outer surface of the rear end of the pull rod is provided with a thread. The pull rod is connected to the drainage pipe through its drainage port and is connected to the tray through a nut.

[0017] In a preferred embodiment of the present scheme, the pull rod is a smooth variable diameter rod, and the sleeve is further provided with a plurality of deformation guide rails formed by the inner wall thereof protruding inwardly, and the deformation guide rails extend along the axial direction of the sleeve;

[0018] The multiple deformable guide rails are evenly distributed along the radial direction of the sleeve, and the protrusion heights of the multiple deformable guide rails increase from small to large from front to back;

[0019] When the pull rod is pulled away from the sleeve and a relative displacement occurs, the protruding deformable guide rail on the inner wall of the sleeve is squeezed outward by the pull rod, causing the sleeve wall to expand and squeeze the inner wall of the anchor hole, thereby generating a tangential compression force p. τ .

[0020] In a preferred embodiment of this scheme, the water-sudden high-in-situ stress soft rock tunnel support structure also includes a lining, the main body of the drainage pipe is located between the primary support (anchor mesh spraying support) and the lining, and one end of the drainage pipe is connected to the drainage hole at the rear end of the pull rod, and the other end of the drainage pipe is connected to the drainage facilities of the tunnel. Finally, the water is discharged from the tunnel.

[0021] On the other hand, the present invention also provides a method for supporting a soft rock tunnel with high ground stress caused by sudden water and mud, which is used to form the above-mentioned soft rock tunnel supporting structure with high ground stress caused by sudden water and mud, and comprises the following steps:

[0022] A. Pre-grouting of tunnel surrounding rock

[0023] In the rock mass in front of the unexcavated tunnel face, the required tunnel surrounding rock pre-grouting area is determined according to the development of engineering diseases, and pre-grouting is carried out; wherein, after the grouting body is injected, the outer tunnel surrounding rock forms a bonding layer capable of bearing the outer surrounding rock pressure and the original rock groundwater pressure;

[0024] B. Regionalization of anchor support functions

[0025] After pre-grouting, the rock mass in front of the tunnel face is excavated according to the designed advance; after excavation, the newly exposed surrounding rock mass and tunnel face are sealed with sprayed concrete, and then the initial support construction of the tunnel is carried out;

[0026] The initial support construction includes hanging nets, supporting steel frames, and installing anchor rods; the anchor rods on the inner wall of the tunnel are consistent with the traditional installation method and are distributed in a diamond shape; the anchor rod structure includes a rod body section, and a functional section connected to the rear end of the rod body section and having drainage and expansion deformation functions, a drainage port is provided at the rear end of the functional section, and an anchor head of the anchor rod structure is provided at the rear end of the functional section;

[0027] After the anchor rod is installed, a certain length of the rod body at the front end of the rod body serves as the anchoring section, which is connected to the outer tunnel surrounding rock through an anchoring agent. The anchor head at the rear end acts on the tunnel rock wall through a tray, and multiple anchored and sealed rod body sections are dispersed in the surrounding rock of the outer tunnel, so that the outer tunnel surrounding rock forms a reinforced water-blocking layer with the function of bearing the pressure of the outer surrounding rock and blocking water. Multiple functional sections are dispersed in the surrounding rock of the inner tunnel, so that the inner tunnel surrounding rock forms a compacted and water-draining layer with the function of compaction and drainage.

[0028] After the rod body section is fixed and installed, the water blocking performance of the reinforced water blocking layer shall not be damaged. The functional section is located in the compacted hydrophobic layer, and the length is consistent with the thickness of the compacted hydrophobic layer.

[0029] In a preferred embodiment of the present invention, a method for supporting a soft rock tunnel with high ground stress due to sudden water and mud inrush further includes step C:

[0030] C. Construction completed

[0031] After the bolt structure is installed, the steel frame and shotcrete are constructed, and then the outlet of the functional section is connected to the drainage pipe. This forms a compacted water-draining layer and a reinforced water-blocking layer of the tunnel surrounding rock with complete functions.

[0032] On the other hand, the present invention also provides a support structure for a soft rock tunnel with high ground stress and water and mud inrush, comprising:

[0033] The reinforced water blocking layer is composed of an outer tunnel surrounding rock, a plurality of rod segments dispersed in the outer tunnel surrounding rock, and a grouting body injected into the outer tunnel surrounding rock, and its periphery is in contact with the original rock to bear the outer surrounding rock pressure and the original rock groundwater pressure;

[0034] A compacted water-draining layer, which is composed of an inner tunnel surrounding rock, a plurality of functional segments dispersed in the inner tunnel surrounding rock, and a grouting body injected into the inner tunnel surrounding rock, and is located inside the reinforced water-blocking layer;

[0035] Among them, the functional section and the rod body section are connected one by one to form an integral anchor structure. The functional section penetrates the compacted hydrophobic layer along the tunnel radial direction. The functional section has drainage and expansion deformation functions. A drainage outlet is provided at the rear end of the functional section. At the same time, an anchor head of the anchor structure is provided at the rear end of the functional section. The anchor head acts on the tunnel rock wall through the tray, and forms a primary support structure with the composite support material steel mesh, steel frame and shotcrete outside the tunnel rock wall.

[0036] In a preferred embodiment of the present scheme, the functional section includes a sleeve that can generate displacement along its radial direction to achieve expansion deformation, and a pull rod sleeved in the sleeve, the front end of the sleeve is connected to the rear end of the rod body section, the rear end of the pull rod passes through the rear end opening of the sleeve, and the anchor head is arranged at the rear end of the pull rod;

[0037] The pull rod can be relatively displaced relative to the sleeve, so that the functional section can be stretched and deformed along the axial direction of its anchor structure, and when the pull rod is relatively displaced relative to the sleeve, the pull rod squeezes the inner wall of the sleeve to cause the sleeve to expand and deform;

[0038] When the sleeve expands and deforms, the sleeve squeezes the tunnel surrounding rock in the tunnel tangentially to generate a tangential compression force p τ .

[0039] In a preferred embodiment of the present scheme, a plurality of water-permeable deformation joints are provided on the sleeve, the pull rod is a hollow pull rod, and a plurality of small holes are provided on the pull rod. The pore water in the rock mass of the compacted hydrophobic layer can enter the sleeve along the water-permeable deformation joints and then enter the pull rod through the small holes, and finally be discharged from the rock mass by the pull rod.

[0040] In a preferred embodiment of the present scheme, the support structure for high-stress soft rock tunnel with sudden water and mud also includes a drainage pipe. The outer surface of the rear end of the pull rod is provided with a thread. The pull rod is connected to the drainage pipe through its drainage port and is connected to the tray through a nut.

[0041] In a preferred embodiment of the present scheme, the pull rod is a smooth variable diameter rod, and a plurality of deformation guide rails formed by the inner wall of the sleeve protruding inward are provided in the sleeve, and the deformation guide rails extend along the axial direction of the sleeve;

[0042] The multiple deformable guide rails are evenly distributed along the radial direction of the sleeve, and the protrusion heights of the multiple deformable guide rails increase from small to large from front to back;

[0043] When the pull rod is pulled away from the sleeve to cause relative displacement, the protruding deformable guide rail on the inner wall of the sleeve is squeezed outward by the pull rod, causing the sleeve wall to expand and squeeze the inner wall of the anchor hole, thereby generating a tangential compression force p. τ .

[0044] In a preferred embodiment of the present scheme, the support structure for the soft rock tunnel with high ground stress and sudden water and mud also includes a lining and a drainage pipe located between the primary support anchor mesh spray support and the lining, one end of the drainage pipe is connected to the drainage hole at the rear end of the pull rod, and the other end of the drainage pipe is connected to the drainage facilities of the tunnel.

[0045] On the other hand, the present invention also provides a method for supporting a soft rock tunnel with high ground stress caused by sudden water and mud, which is used to form the above-mentioned soft rock tunnel supporting structure with high ground stress caused by sudden water and mud, and comprises the following steps:

[0046] A. Pre-grouting of tunnel surrounding rock

[0047] In the rock mass in front of the unexcavated tunnel face, the required tunnel surrounding rock pre-grouting area is determined according to the development of engineering diseases, and pre-grouting is carried out; wherein, after the grouting body is injected, the outer tunnel surrounding rock forms a bonding layer capable of bearing the outer surrounding rock pressure and the original rock groundwater pressure;

[0048] B. Regionalization of anchor support functions

[0049] After pre-grouting, the rock mass in front of the tunnel face is excavated according to the designed advance; after excavation, the newly exposed surrounding rock mass and tunnel face are sealed with sprayed concrete, and then the initial support construction of the tunnel is carried out;

[0050] The initial support construction includes hanging nets, supporting steel frames, and installing anchor rods; the anchor rods on the inner wall of the tunnel are consistent with the traditional installation method and are distributed in a diamond shape; the anchor rod structure includes a rod body section, and a functional section connected to the rear end of the rod body section and having drainage and expansion deformation functions, a drainage port is provided at the rear end of the functional section, and an anchor head of the anchor rod structure is provided at the rear end of the functional section;

[0051] After the anchor rod is installed, a certain length of the rod body at the front end of the rod body serves as the anchoring section, which is connected to the outer tunnel surrounding rock through an anchoring agent. The anchor head at the rear end acts on the tunnel rock wall through a tray, and multiple anchored and sealed rod body sections are dispersed in the surrounding rock of the outer tunnel, so that the outer tunnel surrounding rock forms a reinforced water-blocking layer with the function of bearing the pressure of the outer surrounding rock and blocking water. Multiple functional sections are dispersed in the surrounding rock of the inner tunnel, so that the inner tunnel surrounding rock forms a compacted and water-draining layer with the function of compaction and drainage.

[0052] The rod section shall not damage the water blocking performance of the reinforced water blocking layer after fixed installation. The functional section is located in the compacted water-repellent layer, and its length is consistent with the thickness of the compacted water-repellent layer.

[0053] In a preferred embodiment of the present invention, a method for supporting a soft rock tunnel with high ground stress due to sudden water and mud inrush further includes step C:

[0054] C. Construction completed

[0055] After the bolt structure is installed, the steel frame and shotcrete are constructed, and then the outlet of the functional section is connected to the drainage pipe. This forms a compacted water-draining layer and a reinforced water-blocking layer of the tunnel surrounding rock with complete functions.

[0056] It should be noted that traditional surrounding rock construction is to calculate the overall mechanical properties and hydraulic properties of the surrounding rock to meet the needs of the project; while in the present invention, the reinforced water-blocking layer and the compacted hydrophobic layer form an inner and outer circle structure, and the outer circle (reinforced water-blocking layer) has a compressive effect, and while playing a compressive effect, the outer circle also reduces the permeability of water, reduces the absolute amount of water flowing to the inner circle, and gradually reduces the water pressure u of the tunnel surrounding rock along the radial direction; the inner circle (compacted hydrophobic layer) mainly plays a hydrophobic role, and the grouting of the inner circle only needs to ensure its stability, that is, during the design process, the inner circle is guaranteed to have good drainage characteristics on the basis of ensuring that its deformation meets the requirements of the project deformation.

[0057] In the present invention, the functional segment can generate displacement along its radial direction to achieve expansion deformation, so as to generate tangential compression force p in the tunnel tangentially squeezing the tunnel surrounding rock. τ , thus forming the tangential support force p τ , the compacted hydrophobic layer is subjected to the tangential support force p τ Under the pressure exerted by the reinforced water blocking layer, a bidirectional squeezing effect is formed to promote the flow of pore water to the functional section with drainage function.

[0058] Why doesn't the present invention process the "compacted hydrophobic area" of the inner circle and the "reinforced water blocking area" of the outer circle into materials with better water blocking performance through grouting and other measures? This is because, after the tunnel is excavated in the rock mass, the stress field of the surrounding rock undergoes a secondary distribution, and deformation and cracking of the surrounding rock near the rock wall of the tunnel are inevitable. Even if the strength of the surrounding rock is increased and the permeability is reduced through pre-grouting, the surrounding rock mass after cracking still has good water conductivity characteristics, and absolute water blocking is in principle unattainable. Therefore, since it is impossible to avoid the cracking and deformation of the surrounding rock near the tunnel, it is better to drain water directly to reduce the softening effect of water on the surrounding rock. Such optimization of the engineering structure is based on realistic considerations and trade-offs, and is worse than the direct hard resistance to surrounding rock deformation and the absolute water blocking strategy.

[0059] Compared with the prior art, the beneficial effects of the present invention include at least one of the following:

[0060] (1) The present invention proposes a high-stress soft rock tunnel support structure for water and mud inrush, which forms a "far defense and near drainage" in the control of high water pressure and large water volume in the tunnel surrounding rock, that is, in the surrounding rock mass after lining, the inner circle is constructed as a "compacted water-draining zone" and the outer circle is constructed as a "reinforced water blocking zone". The effects of this are: the outer circle reduces the permeability of water, reduces the absolute amount of water flowing into the inner circle, and gradually reduces the water pressure u of the tunnel surrounding rock inward along the radial direction; under the action of the functional section of the internal anchor rod, the pore water of the inner circle seeps into the inside of the anchor rod, and the pore water is discharged through the anchor rod, which can reduce the water content w of the rock mass; in addition, the rock mass is subjected to the internal lining support force and the pressure of the outer circle rock mass in the radial direction, and the internal tangential pressure generated by the expansion of the anchor rod is subjected to the tangential pressure, forming a bidirectional extrusion effect, which promotes the pore water to flow to the anchor rod with drainage function; by reducing the water content of the rock mass in the inner circle compacted water-draining layer, the softening effect of water on the rock mass is reduced, the mechanical strength of the rock mass is improved, and the occurrence of water and mud inrush accidents is reduced.

[0061] (2) In the present invention, the double ring layer in the tunnel surrounding rock not only optimizes the drainage function in space, but also has the mechanical effect of the double ring layer, forming a bearing capacity amplification mechanism of a double pressure arch, thereby improving the mechanical stability of the surrounding rock. For example, the anchor rods of the lining and the initial support work together to generate support pressure p on the inner wall of the tunnel surrounding rock. r The expansion deformation of the anchor rod during tensile deformation tangentially squeezes the surrounding rock of the inner ring layer to generate a tangential support force p τ , so that the tangential stress σ θ The outer side of the inner ring is subjected to the radial extrusion force of the outer ring. r，c-s Therefore, the inner layer (i.e., the compacted hydrophobic layer) is subjected to bidirectional extrusion, which forms an internal "pressure arch" in stress-deformation and exerts a certain bearing capacity. τUnder the action of the inner circle rock mass, the inner circle rock mass can provide greater radial bearing stress to the outer circle (reinforced water blocking layer) through the "pressure arch". The mechanical properties of the rock mass in the outer circle (reinforced water blocking area) have been improved through grouting and support, and it is also in a multi-directional stress state. When the support force of the inner circle compaction and water-repellent zone increases, the stress state of the rock mass is improved, and through the "pressure arch" effect, it can provide greater support reaction force to the external original rock.

[0062] (3) Coupling of the bearing function and drainage function of the surrounding rock mass. For water burst and mud burst diseases, water is the main inducing factor leading to the disease, while the mechanical stability of the rock mass is the direct factor causing the disease. Simply controlling water or reinforcing the rock mass is not a perfect measure, especially for soft rock tunnels with high ground stress and high water pressure, the long-term safety is greatly challenged. The double-ring design involved in the present invention involves the following coupling effects of structural stress and drainage: (a) The inner ring (i.e., the compacted hydrophobic layer), under the multi-directional squeezing action of the support structure and the surrounding rock mass, is conducive to the discharge of pore water to the drainage channel; conversely, the reduction of pore water content can improve the mechanical properties of the rock mass, so that the rock mass structure can withstand a larger load, which is more conducive to drainage. (b) The outer layer (i.e. the reinforced water blocking layer) fully exerts the bearing capacity of the rock mass through the "pressure arch" effect under the radial compression of the inner layer and the outer original rock. The greater the radial force of the inner layer, the higher the bearing capacity, the denser the rock mass is under pressure, and the lower the rock mass permeability, so that the effect of water blocking and reducing pore pressure is better. Conversely, the denser the rock mass, the lower the pore water pressure, the better the mechanical properties of the rock mass, and the better the bearing capacity of the layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] The above and other objects and / or features of the present invention will become more apparent through the following description in conjunction with the accompanying drawings, in which:

[0064] Figure 1 A schematic diagram of the structure of an anchor rod according to an exemplary embodiment of the present invention is shown;

[0065] Figure 2 A schematic diagram of an anchor rod structure according to an exemplary embodiment of the present invention is shown;

[0066] Figure 3 A schematic diagram showing the structure of the coupling between the anchor rod and the tray according to an exemplary embodiment of the present invention is shown;

[0067] Figure 4 A schematic cross-sectional view of a sleeve of an exemplary embodiment of the present invention is shown (in the figure, MM is a schematic cross-sectional view of the front portion of the sleeve, and NN is a schematic cross-sectional view of the rear portion of the sleeve);

[0068] Figure 5A schematic diagram of the anti-drainage principle of a support structure for a high-in-situ stress soft rock tunnel with sudden water and mud is shown in the present invention;

[0069] Figure 6 A schematic diagram showing the supporting effect of a support structure for a high-in-situ stress soft rock tunnel with sudden water and mud inrush according to the present invention is shown;

[0070] Figure 7 A schematic diagram showing the drainage principle of a support structure for a soft rock tunnel with high ground stress and sudden water and mud inrush according to the present invention is shown;

[0071] Figure 8 A schematic diagram of the division of a water-burst and mud-burst high-in-situ stress soft rock tunnel support structure in a circular tunnel according to the present invention is shown;

[0072] Fig. 9 A schematic diagram showing a comparison diagram of grouting areas of a method for supporting a soft rock tunnel with high ground stress and water and mud inrush according to the present invention is shown;

[0073] Fig.10 A schematic diagram of the grouting area of ​​a method for supporting a soft rock tunnel with high ground stress and sudden water and mud inrush according to the present invention is shown;

[0074] Fig.11 The present invention shows the radius design process of the compacted drainage area and the reinforced water blocking area of ​​a high-in-situ stress soft rock tunnel support method for water and mud inrush according to the present invention;

[0075] Fig.12 A schematic diagram of the mechanism of the support structure and method for a soft rock tunnel with high ground stress and sudden water and mud inrush of the present invention is shown.

[0076] Explanation of main figure marks: 1. tray; 2. sleeve; 3. rod section; 4. functional section; 5. water filtration layer; 6. pull rod; 7. water-conducting core pipe; 8. drainage pipe; 9. insulation layer; 01. reinforced water-blocking layer; 02. compacted hydrophobic layer; 03. primary lining; 04. lining; 201. expansion joint; 202. deformation guide rail; A. deep water-blocking reinforcement grouting area; B. behind-the-wall grouting reinforcement area; C. temporary water-blocking grouting reinforcement area. DETAILED DESCRIPTION

[0077] Hereinafter, a support structure and method for a soft rock tunnel with high ground stress and water and mud inrush according to the present invention will be described in detail in combination with exemplary embodiments.

[0078] It should be noted that “upper”, “lower”, “front”, “back”, “left”, “right”, “inside”, “outside”, etc. are merely for the convenience of description and to constitute relative orientation or position relationships, and do not indicate or imply that the referred to component must have this specific orientation or position.

[0079] Figure 1A schematic diagram of the structure of an anchor rod according to an exemplary embodiment of the present invention is shown; Figure 2 A schematic diagram of an anchor rod structure according to an exemplary embodiment of the present invention is shown; Figure 3 A schematic diagram showing the structure of the coupling between the anchor rod and the tray according to an exemplary embodiment of the present invention is shown; Figure 4 A schematic cross-sectional view of a sleeve of an exemplary embodiment of the present invention is shown (in the figure, MM is a schematic cross-sectional view of the front portion of the sleeve, and NN is a schematic cross-sectional view of the rear portion of the sleeve); Figure 5 A schematic diagram showing the waterproofing and drainage principle diagram of a support structure for a high-in-situ stress soft rock tunnel with sudden water and mud is shown according to an exemplary embodiment of the present invention; Figure 6 A schematic diagram showing the supporting effect of a support structure for a high-in-situ stress soft rock tunnel of a sudden water and mud burst according to an exemplary embodiment of the present invention is shown;

[0080] Figure 7 A schematic diagram showing the drainage principle of a support structure for a high-in-situ stress soft rock tunnel with sudden water and mud is shown according to an exemplary embodiment of the present invention; Figure 8 A schematic diagram of the division of a water-and-mud-inrush high-stress soft rock tunnel support structure in a circular tunnel according to an exemplary embodiment of the present invention is shown.

[0081] Exemplary Embodiment 1

[0082] A support structure for a soft rock tunnel with high ground stress and sudden water and mud, wherein the surrounding rock of the tunnel is planned into a compacted water-repellent layer 02 and a reinforced water-blocking layer 01 according to its function through engineering measures, wherein the reinforced water-blocking layer 01 is composed of an outer layer of tunnel surrounding rock, a plurality of rod segments 3 dispersed in the outer layer of tunnel surrounding rock, and a grouting body injected into the outer layer of tunnel surrounding rock, and has the function of bearing the outer surrounding rock pressure and the original rock groundwater pressure to block water, and its The outer perimeter is the original rock mass; the compacted water-draining layer 02 is located inside the reinforced water-blocking layer 01, and is composed of the inner tunnel surrounding rock, a plurality of functional segments 4 dispersed in the inner tunnel surrounding rock, and a grouting body injected into the inner tunnel surrounding rock. Its outer periphery is in contact with the reinforced water-blocking layer 01, and it has the function of providing a supporting reaction force to the reinforced water-blocking layer 01 to improve the stress state of the reinforced water-blocking layer 01. At the same time, the inner tunnel surrounding rock cooperates with the functional segment 4 to enable it to have the functions of compaction and drainage;

[0083] Among them, the functional section 4 is connected to the rod body section 3 in a one-to-one correspondence to form an integral anchor rod structure. The functional section 4 penetrates the compacted hydrophobic layer 02 along the tunnel radial direction. The functional section 4 has drainage and expansion deformation functions. A drainage port is provided at the rear end of the functional section 4. At the same time, an anchor head of the anchor rod structure is provided at the rear end of the functional section 4. The anchor head acts on the tunnel rock wall through the tray 1, and forms a primary support structure with the composite support material steel mesh, steel frame, and shotcrete outside the tunnel rock wall.

[0084] In this scheme, the tunnel surrounding rock reinforcement water blocking layer 01, compacted water-repellent layer 02 and primary support structure cooperate with each other in stress field and seepage field to form the following mechanism:

[0085] The primary support structure forms a compaction and large deformation support effect on the compaction water-repellent layer 02, improves the stress state of the surrounding rock in the compaction water-repellent layer 02, and provides a certain surrounding rock bearing capacity, so that the primary support structure can provide a supporting reaction force to the external reinforcement water-blocking layer 01;

[0086] After reinforcement and improvement of stress state, the reinforced water-blocking layer 01 gives full play to the bearing capacity of the surrounding rock mass and ensures the stability of the surrounding rock mass; after grouting and plugging of the reinforced water-blocking layer 01, the permeability is reduced, and the seepage volume of groundwater to the internal compacted hydrophobic layer 02 is controlled, while at the same time, it bears most of the pore water pressure; under the action of compaction and drainage, the compacted hydrophobic layer 02 promotes the discharge of a small amount of infiltrated pore water, reduces the water content and water pressure in the rock mass, and thus improves the mechanical strength of the surrounding rock mass, which helps to improve the structural stability.

[0087] In a preferred embodiment of the present scheme, the front section of the rod section 3 is connected to the reinforced water blocking layer 01 as an anchoring section for anchoring (the anchoring section and the reinforced water blocking layer 01 are combined to form a reinforced water blocking effect), and the rear free section of the rod section 3 is connected to the functional section 4 (having compaction and drainage functions), and the functional section 4 is located in the compaction hydrophobic layer 02 to realize the drainage of the compaction hydrophobic layer 02.

[0088] In a preferred embodiment of the present scheme, the functional section 4 includes a sleeve 2 and a pull rod 6, the front end of the sleeve 2 is connected to the rear end of the rod body section 3; the pull rod 6 is sleeved in the sleeve 2, and its rear end passes through the rear end opening of the sleeve 2; the pull rod 6 can be relatively displaced relative to the sleeve 2, so that the functional section 4 can be stretched and deformed along the axial direction of its anchor rod, and at the same time squeeze the inner wall of the sleeve 2 to cause the sleeve 2 to expand and deform; and when the sleeve 2 expands and deforms, the sleeve 2 squeezes the tunnel surrounding rock in the tunnel tangential direction to generate a tangential compression force p τ The anchor head is arranged at the rear end of the tie rod 6. After the functional section 4 penetrates the compacted hydrophobic layer 02 along the radial direction of the tunnel, it is connected to the tray 1 through the anchor head on the tie rod 6.

[0089] When the sleeve 2 of the functional section 4 is stretched and deformed along the axial direction of the anchor rod, it can continue to apply anchoring force to the rock mass without failure.

[0090] In a preferred embodiment of the present scheme, a plurality of water-permeable deformation joints 201 are provided on the sleeve 2, the pull rod 6 is a hollow pull rod, and a plurality of small holes are provided on the pull rod 6. The pore water in the rock mass of the compacted hydrophobic layer 02 can enter the sleeve 2 along the water-permeable deformation joints 201 and then enter the pull rod 6 through the small holes, and finally be discharged from the rock mass through the drainage port at the rear end of the pull rod 6.

[0091] In a preferred embodiment of the present scheme, the support structure for the soft rock tunnel with high ground stress and sudden water and mud also includes a drainage pipe 8. The outer surface of the rear end of the pull rod 6 is provided with a thread. The pull rod 6 is connected to the drainage pipe 8 through its drainage port and is simultaneously connected to the tray 1 through a nut.

[0092] In a preferred embodiment of the present scheme, the pull rod 6 is a smooth variable diameter rod, and the sleeve 2 is further provided with a plurality of deformation guide rails 202 formed by the inner wall thereof protruding inwardly, and the deformation guide rails 202 extend axially along the sleeve 2;

[0093] The multiple deformable guide rails 202 are evenly distributed along the radial direction of the sleeve 2, and the protrusion heights of the multiple deformable guide rails 202 increase from small to large from front to back;

[0094] When the pull rod 6 is pulled away from the sleeve 2 and relatively displaced, the protruding deformable guide rail 202 on the inner wall of the sleeve 2 is squeezed outward by the pull rod 6, causing the sleeve 2 to expand and displace to squeeze the inner wall of the anchor hole, thereby generating a tangential compression force p τ .

[0095] In a preferred embodiment of this scheme, the water-sudden high-stress soft rock tunnel support structure further includes a lining 04, a drainage pipe 8 body is located between the primary support anchor mesh spraying support and the lining 04, and one end of the drainage pipe 8 is connected to the drainage hole at the rear end of the pull rod 6, and the other end of the drainage pipe 8 is connected to the drainage facilities of the tunnel. Finally, the water is discharged from the tunnel.

[0096] Exemplary Embodiment 2

[0097] A method for supporting a soft rock tunnel with high ground stress and water and mud inrush, which is used to form the above-mentioned soft rock tunnel supporting structure with high ground stress and water and mud inrush, comprises the following steps:

[0098] A. Pre-grouting of tunnel surrounding rock

[0099] like Fig. 9 As shown in the figure, in the rock mass in front of the unexcavated tunnel face, according to the development of engineering diseases, the required tunnel surrounding rock pre-grouting area is determined by Table 1, and the grouting slurry is selected from materials that have the dual functions of strengthening the rock mass and blocking water. Fig.10 The grouting body is injected into the A area shown in the figure to form a bonding layer that can bear the outer surrounding rock pressure and the original rock groundwater pressure, which will serve as the future reinforcement and water blocking layer 01 area. Whether other areas (B, C) need grouting is determined according to the disease development conditions shown in Table 1. When the tunnel needs to grout the inner layer of the tunnel surrounding rock, because the inner layer of the surrounding rock is close to the tunnel excavation wall, deformation and cracks will occur after excavation regardless of whether grouting is performed, and even if grouting is performed, permeable drainage cracks can be formed.

[0100] B. Regionalization of anchor support functions

[0101] After pre-grouting, the rock mass in front of the tunnel face is excavated according to the designed advance. After excavation, the newly exposed surrounding rock mass and tunnel face are sprayed with concrete as soon as possible, and then the initial support construction of the tunnel is carried out as soon as possible, such as hanging nets, installing anchor rods, supporting steel frames, and spraying concrete again.

[0102] The anchor rods on the inner wall of the tunnel are basically the same as the traditional installation method and are also distributed in a diamond shape. The anchor rod structure includes a rod body section 3, and a functional section 4 connected to the rear end of the rod body section 3 and having drainage and expansion deformation functions. The rear end of the functional section 4 is provided with a drainage port, and the rear end of the functional section 4 is provided with an anchor head of the anchor rod structure;

[0103] After installation, a certain length of the rod body at the front end of the rod body segment 3 is used as an anchoring segment, which is connected to the outer tunnel surrounding rock through an anchoring agent, and the anchor head at the rear end acts on the tunnel rock wall through the tray 1, and multiple anchoring and sealing rod body segments 3 are dispersed in the surrounding rock of the outer tunnel, so that the outer tunnel surrounding rock forms a reinforced water blocking layer 01 with the function of bearing the outer surrounding rock pressure and blocking water, and multiple functional segments 4 are dispersed in the surrounding rock of the inner tunnel, so that the inner tunnel surrounding rock forms a compacted water-repellent layer 02 with the function of compaction and drainage;

[0104] After the rod body section 3 is fixedly installed, the water blocking performance of the reinforced water blocking layer 01 shall not be damaged. The functional section 4 is located in the compacted hydrophobic layer 02, and its length is consistent with the thickness of the compacted hydrophobic layer 02.

[0105] In a preferred embodiment of the present invention, a method for supporting a soft rock tunnel with high ground stress due to sudden water and mud inrush further includes step C:

[0106] C. Construction completed

[0107] After the bolt structure is installed, the steel frame and shotcrete are constructed, and then the outlet of the functional section 4 is connected to the drainage pipe 8. Thus, the compacted water-repellent layer 02 and the reinforced water-blocking layer 01 of the tunnel surrounding rock with complete functions are formed.

[0108] In traditional surrounding rock construction, the mechanical and hydraulic properties of the surrounding rock as a whole are calculated to meet the needs of the project. In the present invention, the reinforced water-blocking layer 01 and the compacted hydrophobic layer 02 form an inner and outer ring structure. The outer ring (reinforced water-blocking layer 01) has a compressive effect, and while playing a compressive effect, the outer ring also reduces the permeability of water, reduces the absolute amount of water flowing to the inner ring, and gradually reduces the water pressure u of the tunnel surrounding rock along the radial direction. The inner ring (compacted hydrophobic layer 02) mainly plays a hydrophobic role, and the grouting of the inner ring only needs to ensure its stability. That is, during the design process, the inner ring is guaranteed to have good drainage characteristics on the basis of ensuring that its deformation meets the requirements of the project deformation.

[0109] In this exemplary embodiment, the functional segment 4 can generate displacement along its radial direction to achieve expansion deformation, so as to generate tangential support force ρ in the tunnel tangentially squeezing the surrounding rock. τ , the compacted hydrophobic layer 02 is subjected to the tangential support force ρ τ Under the pressure exerted by the reinforced water blocking layer 01, a bidirectional squeezing effect is formed to make the pore water flow to the functional section 4 with drainage function.

[0110] In the process of pre-grouting of surrounding rock and construction of inner and outer ring layers, grouting reinforcement is the first step of this exemplary embodiment. The radial range of grouting reinforcement needs to meet the radius ρ of the reinforced water blocking area. s , the grouting reinforcement construction process can adopt the conventional grouting reinforcement process. Considering the disaster-causing characteristics of different diseases such as water burst and mud burst, the specific grouting range and grouting time can be selected according to the specific situation, such as whether the rock mass in front of the face needs to be grouting reinforced, whether the rock mass near the tunnel rock wall needs to be reinforced, and whether it is pre-grouting before excavation or grouting after excavation and concrete reinforcement. All of these can be determined according to the specific situation (the grouting range and grouting time are existing conventional treatment processes, which will not be specifically expanded in this exemplary embodiment).

[0111] In this exemplary embodiment, the radius of the compacted hydrophobic area is ρ c In the implementation design process of this exemplary embodiment, not only the traditional anchor spraying support design is included, but also the design and verification of the radius of the compaction drainage area and the reinforcement water blocking area.

[0112] The radius of the compaction water-draining area and the reinforcement water-blocking area (ρ c , s ), which is determined by the control effect of the rock mass-support structure on groundwater and the stability of the surrounding rock mass. c , s To obtain ρ, it is only necessary to verify the mechanical properties and hydraulic properties of the grouting rock mass during design so that ρ c , s The size of the anchor spraying net can meet the project's control effect on groundwater and the stability of the surrounding rock mass. Then, the initial design of the anchor spraying net primary support is carried out, and the water blocking and drainage performance of the surrounding rock-support structure after the completion of the primary support is verified. In addition, as with the traditional primary support, the convergence of the tunnel section deformation needs to be tested to ensure that the structural stability and deformation meet the requirements. When verifying the primary support structure, the physical model with water-physics coupling between the rock mass and groundwater is preferably used for multi-field coupling calculation.

[0113] In order to better understand the inventive concept of the present invention, it is further described below in conjunction with specific embodiments.

[0114] Example 1

[0115] refer to Figure 5 , Figure 6 As shown, a support structure for a soft rock tunnel with high ground stress and sudden water and mud is provided, including a compacted hydrophobic layer 02 and a reinforced water-blocking layer 01 arranged inside and outside, a lining 04 located inside the compacted hydrophobic layer 02, a primary lining 03 located between the compacted hydrophobic layer 02 and the lining 04, and a plurality of anchor structures arranged at intervals along the circumference of the tunnel.

[0116] Among them, the reinforced water-blocking layer 01 is closely attached to the original rock to bear the outer surrounding rock pressure and reduce the permeability; the compacted water-repellent layer 02 is located on the inner side of the reinforced water-blocking layer 01 to drain water; the anchor rod structure includes an anchor rod, the front end of the anchor rod is connected to the reinforced water-blocking layer 01, the rear end of the anchor rod penetrates the compacted water-repellent layer 02 along the tunnel radial direction and is coupled with a tray 1, and the rear end of the anchor rod has water-conducting properties.

[0117] refer to Figure 1 to Figure 3 As shown, in this embodiment, the anchor rod includes a rod body segment 3 and a functional segment 4. The front section of the rod body segment 3 is used for anchoring, and the rear end of the rod body segment 3 is connected to the functional segment 4. The functional segment 4 has a drainage function, and the functional segment 4 is located in the compacted hydrophobic layer 02, thereby realizing the efficient drainage performance of the compacted hydrophobic layer 02.

[0118] Furthermore, in this solution, the functional section 4 also has an expansion characteristic, that is, the functional section 4 can generate a displacement along its radial direction to squeeze the inner wall of the anchor hole, thereby generating a tangential compression force p τ , and then squeeze to produce tangential support force, specifically:

[0119] Functional section 4 includes sleeve 2, the front end of sleeve 2 is connected to the rear end of rod section 3, and sleeve 2 is provided with a plurality of strip-shaped water-permeable deformation joints 201. When the outer wall of sleeve 2 expands outward to generate displacement, the outer wall of sleeve 2 squeezes the surrounding rock in the tunnel tangential direction to generate tangential support force ρ τ The pore water in the compacted hydrophobic layer 02 can enter the sleeve 2 along the permeable deformation joint 201 and then be guided out of the rock mass by the sleeve 2, thus realizing the water-conducting function of the anchor rod.

[0120] In this embodiment, the functional section 4 can automatically expand and deform after the rock mass absorbs water. For details, refer to Figure 2 , Figure 7As shown, the functional section 4 includes a rod 6 arranged in the sleeve 2, and a plurality of water-permeable deformation joints 201 are provided on the sleeve 2. The rod 6 is a hollow rod, and a plurality of small holes are provided on the rod 6. The pore water in the rock mass of the compacted hydrophobic layer 02 can enter the sleeve 2 along the water-permeable deformation joints 201 and then enter the rod 6 through the small holes, and finally be discharged from the rock mass through the drainage port at the rear end of the rod 6; and the rod 6 is a smooth variable diameter rod, and a plurality of deformation guides formed by the inner wall bulging inward are also provided in the sleeve 2. The deformable guide rail 202 extends axially along the sleeve 2; multiple deformable guide rails 202 are evenly distributed along the radial direction of the sleeve 2, and the protrusion heights of the multiple deformable guide rails 202 increase from small to large from front to back; when the pull rod 6 is pulled away from the sleeve 2 and relatively displaced, the protruding deformable guide rail 202 on the inner wall of the sleeve 2 is squeezed outward by the pull rod 6, so that the wall of the sleeve 2 expands and displaces to squeeze the inner wall of the anchor hole, thereby generating a tangential pressing force p τ .

[0121] In this embodiment, the support structure for the soft rock tunnel with high ground stress and sudden water and mud also includes a drainage pipe 8. The outer surface of the rear end of the pull rod 6 is provided with a thread. The pull rod 6 is connected to the drainage pipe 8 through its drainage port and is connected to the tray 1 through a nut.

[0122] Further, in this embodiment, reference Figure 2 As shown, the rear end of the pull rod 6 is cylindrical, and the front end is cone, and the small dome of the cone is equal to the diameter of the cylinder; Figure 4 As shown, the inner wall of the sleeve 2 is protruded inward to form a plurality of deformable guide rails 202 ; the plurality of deformable guide rails 202 are adapted to the pull rod 6 .

[0123] Further, in this embodiment, reference Figure 2 , Figure 4 As shown, the hollow inner cavity of the pull rod 6 is also provided with a water filter layer 5, and the water filter layer 5 is a tubular filter material.

[0124] In this embodiment, the pull rod 6 is further refined to enhance the water conduction capacity of the pull rod 6. Specifically, in this embodiment, a water conduction core tube 7 is further provided inside the water filter layer 5, through which the water filtered by the water filter layer 5 can be collected and drained out of the rock body.

[0125] In this embodiment, the anchor rod is a bonding anchor rod, and the front section of the rod section 3 is the bonding end; after the support structure is constructed, the bonding end of the front end of the rod section 3 is bonded to reinforce the water blocking layer 01, and the rear end of the pull rod 6 penetrates the compacted hydrophobic layer 02 along the tunnel radial direction and is connected to the tray 1 to apply a certain preload force to the anchor rod.

[0126] refer to Figure 7As shown, in this embodiment, the drainage pipe 8 is connected to the tunnel drainage channel or the tunnel drainage pipe to form a drainage passage; a waterproof layer and a thermal insulation layer 9 material are also laid between the lining 04 and the primary lining 03.

[0127] In this embodiment, the primary lining 03 is supported by anchor spraying. During the construction process, after the anchoring agent at the anchor end of the anchor rod solidifies, the mesh installation tray 1 and the nut are hung; then the drainage pipe 8 behind the lining wall is connected to the exposed drainage hole of the anchor rod (the end of the filter layer 5) to form a drainage passage, and then concrete is sprayed to form the primary support structure.

[0128] The support structure for high-in-situ stress soft rock tunnels with water and mud inrush proposed in this disclosure can be used to control water and mud inrush disasters, reduce large deformation of soft rock, and reduce surrounding rock pressure on lining 04 during the construction and operation of high-in-situ stress and high water pressure soft rock tunnels, thereby preventing deformation, cracking and water seepage of lining 04. Figure 8 As shown, the disclosed technology and structure constructs a reinforced water-blocking layer 01 and a compacted water-draining zone ring layer 02 in the tunnel surrounding rock after construction, so that a dynamic gradually stable system is formed between the tunnel surrounding rock, groundwater and the tunnel support structure, and the coupling of structural stress-water pressure-material together constitutes a stable structure.

[0129] The stable structure has many advantages, including:

[0130] (1) From a structural perspective, the principle of “far defense and near sparseness” is used to control the high water pressure and large water volume in the tunnel surrounding rock (e.g. Figure 5 As shown), in the surrounding rock mass after lining 04, the inner circle is constructed as a "compacted water-draining zone" and the outer circle is constructed as a "reinforced water-blocking zone". The effect of this is: the outer circle reduces the permeability of water, reduces the absolute amount of water flowing to the inner circle, and gradually reduces the water pressure u of the tunnel surrounding rock along the radial direction. The rock mass of the inner circle is radially subjected to the pressure of the internal lining support force and the outer circle rock mass. The tangential pressure generated by the expansion of the anchor rod forms a bidirectional extrusion effect, causing the pore water to flow toward the anchor rod with drainage function (the drainage route is as shown in the figure). Figure 5 , Figure 7 In this way, the water content w of the inner layer rock mass is reduced, the softening effect of water on the rock mass is reduced, and the occurrence of water and mud inrush accidents is reduced.

[0131] (2) In terms of controlling the stress and deformation of the tunnel surrounding rock, the traditional method of anchor support + hanging mesh + shotcrete was used to form the primary support, and a reinforced concrete lining structure was constructed. The difference is that the surrounding rock was divided into two functional areas according to the function of the anchor structure:

[0132] a) The outer layer surrounding rock is reinforced by grouting, and the radial compressive stress σ rUnder the action of the water-blocking system, a stable "pressure arch" is formed to reinforce the water blocking area, which is the main bearing structure for bearing the outer surrounding rock pressure and controlling the stability and deformation of the rock mass;

[0133] b) The inner ring reduces the softening degree of the rock mass through support and drainage. At the same time, the lining 04 and the anchor rods exert a bidirectional squeezing effect on the rock mass. The primary lining 03 generates a support pressure p on the inner wall of the tunnel surrounding rock. r When the anchor bolt is stretched, it expands and deforms, squeezing the surrounding rock in the tangential direction, generating a tangential support force p τ , in the tangential stress σ θ Under the effect of enlargement, the inner ring layer forms a compaction effect (such as Figure 6 As shown in Figure 2), the inner layer forms an internal "pressure arch" in terms of stress-deformation, which has a certain bearing capacity and can provide radial bearing stress to the outer layer rock mass (the support force of the support effect is shown in Figure 2). Figure 6 At the same time, this compaction effect, combined with the hydrophobic structure, can further reduce the water content of the inner layer rock mass, and reduce water inrush, mud inrush and large deformation of the rock mass.

[0134] When the structure is completed, although the bearing capacity of the inner layer of rock is weaker than that of the outer layer, the key to the inner layer is to maintain its own structural stability and provide radial support force to the outer layer while draining a small amount of water that has seeped into the inner layer.

[0135] Working mechanism of support structure and method for soft rock tunnel with high ground stress caused by sudden water and mud Fig.12 As shown in the figure, by organically combining the pre-grouting of the tunnel surrounding rock and the functional regionalization of anchor support in space, the hydraulic coupling between groundwater and rock mass is controlled to achieve effective control of water and mud inrush diseases in high ground stress soft rock tunnels.

[0136] The drainage structure of the compacted drainage area is as follows Figure 7 As shown, under the action of multi-directional extrusion pressure, the groundwater in the rock mass in this area seeps into the anchor rod with water-conducting function, and the water-conducting pipe inside the anchor rod transports the collected water to the outside of the tunnel excavation surface. The water-conducting pipe inside the anchor rod is connected to the drainage pipe 8 between the primary lining 03 (net spraying support) and the secondary lining (lining 04), and the drainage pipe 8 transports the water to the drainage channel or tunnel drainage pipe of the tunnel, and finally discharges it to the outside of the tunnel.

[0137] Example 2

[0138] This embodiment provides a support method for a support structure of a soft rock tunnel with high ground stress caused by sudden water and mud. The method can construct the support structure described in the above embodiment 1, and specifically comprises the following steps:

[0139] A. Pre-grouting of tunnel surrounding rock

[0140] like Fig. 9As shown in the figure, in the rock mass in front of the unexcavated tunnel face, according to the development of engineering diseases, the required tunnel surrounding rock pre-grouting area is determined by Table 1, and the grouting slurry is selected from materials that have the dual functions of strengthening the rock mass and blocking water. Fig.10 The grouting body is injected into the A area shown in the figure to form a bonding layer that can bear the outer surrounding rock pressure and the original rock groundwater pressure, which will serve as the future reinforcement and water blocking layer 01 area. Whether other areas (B, C) need grouting is determined according to the disease development conditions shown in Table 1. When the tunnel needs to grout the inner layer of the tunnel surrounding rock, because the inner layer of the surrounding rock is close to the tunnel excavation wall, deformation and cracks will occur after excavation regardless of whether grouting is performed, and even if grouting is performed, permeable drainage cracks can be formed.

[0141] B. Regionalization of anchor support functions

[0142] After pre-grouting, the rock mass in front of the tunnel face is excavated according to the designed advance. After excavation, the newly exposed surrounding rock mass and tunnel face are sprayed with concrete as soon as possible, and then the initial support construction of the tunnel is carried out as soon as possible, such as hanging nets, installing anchor rods, supporting steel frames, and spraying concrete again.

[0143] The anchor rods on the inner wall of the tunnel are basically the same as the traditional installation method and are also distributed in a diamond shape. The anchor rod structure includes a rod body section 3, and a functional section 4 connected to the rear end of the rod body section 3 and having drainage and expansion deformation functions. The rear end of the functional section 4 is provided with a drainage port, and the rear end of the functional section 4 is provided with an anchor head of the anchor rod structure;

[0144] After installation, a certain length of the rod body at the front end of the rod body segment 3 is used as an anchoring segment, which is connected to the outer tunnel surrounding rock through an anchoring agent, and the anchor head at the rear end acts on the tunnel rock wall through the tray 1, and multiple anchoring and sealing rod body segments 3 are dispersed in the surrounding rock of the outer tunnel, so that the outer tunnel surrounding rock forms a reinforced water blocking layer 01 with the function of bearing the outer surrounding rock pressure and blocking water, and multiple functional segments 4 are dispersed in the surrounding rock of the inner tunnel, so that the inner tunnel surrounding rock forms a compacted water-repellent layer 02 with the function of compaction and drainage;

[0145] After the rod body section 3 is fixedly installed, the water blocking performance of the reinforced water blocking layer 01 shall not be damaged. The functional section 4 is located in the compacted hydrophobic layer 02, and its length is consistent with the thickness of the compacted hydrophobic layer 02.

[0146] C. Construction completed

[0147] After the bolt structure is installed, the steel frame and shotcrete are constructed, and then the outlet of the functional section 4 is connected to the drainage pipe 8. Thus, the compacted water-repellent layer 02 and the reinforced water-blocking layer 01 of the tunnel surrounding rock with complete functions are formed.

[0148] Furthermore, in this embodiment, during the process of pre-grouting of surrounding rock and construction of inner and outer ring layers, pre-grouting before excavation and post-grouting after excavation spraying concrete reinforcement can be performed before and after the excavation process according to the disaster-causing characteristics of different diseases. The radial range of grouting after excavation spraying concrete reinforcement needs to meet the radius ρ of the reinforced water blocking area. s .

[0149] Specifically, in this embodiment, according to the disaster-causing characteristics of rock mass diseases in a tunnel at a construction site, a support method for a support structure of a soft rock tunnel with sudden water and mud and high ground stress can be specifically refined into the following six steps:

[0150] S1. Full-section pre-grouting

[0151] That is, grouting construction work is carried out at the excavation face, and pre-grouting is carried out in the surrounding rock in front of the entire tunnel. The grouting range includes the reinforced water blocking area (deep water blocking reinforcement grouting area A + temporary water blocking grouting reinforcement area C in front of the face) and the back wall grouting reinforcement area B (reference Fig. 9 , Fig.10 As shown), the surrounding rock forms a relatively dense and impermeable reinforced surrounding rock before excavation; among them, the size of the deep water blocking reinforcement grouting area A is the thickness of the reinforced water blocking layer 01, and the size of the behind-the-wall grouting reinforcement area B is the thickness of the compacted hydrophobic layer 02, thus starting to construct the surrounding rock functional area.

[0152] S2. Excavation work

[0153] According to the designed cycle advance, the surrounding rock of the tunnel face is excavated. It is the same as the general tunnel excavation process, and controlled blasting or mechanical excavation is preferred to reduce the adverse disturbance to the surrounding rock mass.

[0154] S3. Shotcrete reinforcement of newly exposed rock wall surface

[0155] After the rock wall of a newly excavated tunnel is formed, shotcrete sealing should be carried out as soon as possible to reinforce the surrounding rock and control the deterioration rate of the surrounding rock mass.

[0156] S4. Carry out the initial support of anchor spraying net

[0157] Open an anchor hole; after the anchor hole is formed, use the end-bonded anchor described in Example 1, and thread the anchor rod section 3 and the functional section 4 into the borehole (Note: the functional section 4 is prevented from being covered by the anchoring agent in order to ensure the drainage effect), so that the functional section 4 is in the compacted hydrophobic layer 02. The rod section 3 of the anchor is sent to the bottom of the anchor hole and bonded with the anchoring agent. The anchoring agent fully fills the entire borehole of the front section of the rod section 3, and is sealed with the surrounding rock bonding layer, thereby maintaining the water-tightness of the reinforced water-blocking layer 01. After the anchoring agent at the anchoring end solidifies, hang the net to install the tray 1 and the nut. At this time, connect the drain pipe 8 to the exposed drainage hole of the anchor (the end of the pull rod 6) to form a drainage passage. Then spray concrete. From then on, the functional zoning of the compacted hydrophobic layer 02 and the reinforced water-blocking layer 01 of the tunnel surrounding rock is completed.

[0158] S5. Monitoring and measurement after completion of primary support and drainage facilities

[0159] In line with the general tunnel construction specifications, before lining construction, the deformation of the tunnel section after the initial support needs to be monitored and measured, and the working status of the drainage facilities, the amount of water seepage in the tunnel rock wall, and the pore water pressure in the surrounding rock behind the wall need to be tested. If it is found that the drainage volume is too large, the seepage volume is too large, or the pore water pressure is too large, the reinforced water blocking layer 01 can be supplemented with grouting through grouting behind the wall, or the grouting range can be expanded deeper into the surrounding rock until it is improved.

[0160] S6. Lining construction

[0161] When the tunnel section convergence deformation meets the requirements, the drainage channel works normally, and the rock wall permeability is controlled (the drainage volume does not increase but gradually decreases, and there are no quality problems such as pipeline leakage), the lining construction begins. That is, the waterproof layer and insulation layer 9 materials between the lining and the primary support are laid, and the reinforced concrete lining is constructed, and attention is paid to the smoothness of the final drainage channel.

[0162] Furthermore, in order for this implementation to work well, several key technical points of the present invention are described below:

[0163] (1) The radius of the compaction drainage area and the reinforcement water blocking area (ρ c , s ) range. This size is the key to the design of the present invention, and it is related to the final support effect and engineering safety and stability. However, considering the diversity of engineering types, the complexity of rock mass and the influence of various aspects of construction technology, the specific calculation formula and value need to be selected according to the specific construction situation. The following is a design process applicable to most situations, which can be embedded in the construction process of general tunnels:

[0164] A support structure and method for a soft rock tunnel with high ground stress and water inrush and mud inrush, involving the radius of the compacted drainage area and the reinforced water blocking area (ρ c , s ), which is determined by the control effect of the rock mass-support structure on groundwater and the stability of the surrounding rock mass (e.g. Fig.10 The design of the support structure and the determination of related parameters can also be determined and optimized based on the New Austrian Tunneling Method (information-based construction method). Fig.11 As shown in the figure, firstly, the preliminary parameters of tunnel surrounding rock support design can be given based on the empirical analogy method or the theoretical model method of tunnel support structure. These design parameters include the radius of the compaction drainage area and the reinforcement water blocking area (ρ c , s ). Then, a tunnel structural mechanics model is constructed. The model has a water-physics coupling mechanism between the rock mass and groundwater, which can not only realize basic fluid-solid coupling, but also has a water-to-rock softening mechanism. For example, a multi-physics field numerical simulation model based on the finite element method (FEM) is used to test the parameters of the preliminary design. When the model analysis structure shows that the design parameters meet the tunnel's requirements for structural stability, deformation control, and groundwater pressure and seepage control, the design parameters can be preliminarily determined, and the next step of engineering construction and on-site verification can be carried out. On-site monitoring is carried out during and after construction, mainly including tunnel structure safety monitoring, water pressure and flow monitoring in the tunnel surrounding rock, etc. The monitoring data is fed back to the initial design plan and parameters in real time, and the design parameters (including the radius of the compaction drainage area and the reinforcement water blocking area (ρ c , s )).

[0165] During the initial verification of the support structure, the design process not only includes the traditional anchor-spray support design, but also includes the design and verification of the radius of the compacted drainage area and the reinforced water blocking area.

[0166] (2) Grouting reinforcement water blocking area and construction stage. Grouting reinforcement is the first step of the present invention. In addition to the radial range satisfying the radius ρ of the reinforced water blocking area s In addition, the construction process is no different from general grouting reinforcement. However, considering the disaster-causing characteristics of different diseases such as water inrush and mud inrush, the scope of choice is whether the rock mass in front of the face needs to be grouting reinforced, whether the rock mass near the tunnel rock wall needs to be reinforced, whether pre-grouting before excavation or grouting after excavation and concrete spraying reinforcement, which needs to be determined according to the specific situation. Fig. 9 , Fig.10 The grouting reinforcement range shown in the figure can be selected as needed according to the locations where water inrush, mud inrush, large deformation, lining penetration damage, and excessive lining pressure occur. The range of pre-grouting (as shown in Table 1) can be used simultaneously when multiple areas and multiple diseases occur at the same time.

[0167] Table 1 Grouting area selection

[0168]

[0169] Although the present invention has been described above in conjunction with the exemplary embodiments and the accompanying drawings, it should be apparent to those skilled in the art that various modifications may be made to the above-described embodiments without departing from the spirit and scope of the claims.

Claims

1. A support structure for a soft rock tunnel with high ground stress and water and mud inrush, characterized by: The support structure for high-stress soft rock tunnel with sudden water and mud is to plan the surrounding rock of the tunnel into a compacted water-draining layer (02) and a reinforced water-blocking layer (01) according to its function through engineering measures, wherein: A reinforced water blocking layer (01), which is composed of an outer tunnel surrounding rock, a plurality of rod segments (3) dispersed in the outer tunnel surrounding rock, and a grouting body injected into the outer tunnel surrounding rock, and has the function of bearing the outer surrounding rock pressure and the original rock groundwater pressure (water blocking), and the outer perimeter of the reinforced water blocking layer is the original rock mass; A compacted water-repellent layer (02) is located inside the reinforced water-blocking layer (01), and is composed of an inner tunnel surrounding rock, a plurality of functional segments (4) dispersed in the inner tunnel surrounding rock, and a grouting body injected into the inner tunnel surrounding rock. Its periphery is in contact with the reinforced water-blocking layer (01), and it has the function of providing a supporting reaction force to the reinforced water-blocking layer (01) to improve the stress state of the reinforced water-blocking layer (01). At the same time, the inner tunnel surrounding rock cooperates with the functional segment (4) to enable it to have compaction and drainage functions; The functional section (4) and the rod body section (3) are connected in a one-to-one correspondence to form an integral anchor rod structure. The functional section (4) penetrates the compacted hydrophobic layer (02) along the tunnel radial direction. The functional section (4) has drainage and expansion deformation functions. A drainage port is provided at the rear end of the functional section (4). At the same time, an anchor head of the anchor rod structure is provided at the rear end of the functional section (4). The anchor head acts on the tunnel rock wall through the tray (1) and forms a primary support structure with the composite support material outside the tunnel rock wall.

2. A support structure for a soft rock tunnel with high ground stress and water and mud inrush according to claim 1, characterized in that: The front section of the rod section (3) is connected to the reinforced water blocking layer (01) as an anchoring section for anchoring, and the rear section of the rod section (3) is connected to the functional section (4), and the functional section (4) is located in the compacted hydrophobic layer (02) to achieve drainage of the compacted hydrophobic layer (02).

3. A support structure for a soft rock tunnel with high ground stress and water and mud inrush according to claim 2, characterized in that: The functional section (4) comprises a sleeve (2) and a pull rod (6), wherein the front end of the sleeve (2) is connected to the rear end of the rod section (3); The pull rod (6) is sleeved in the sleeve (2), and its rear end passes through the rear end opening of the sleeve (2); The pull rod (6) can be relatively displaced relative to the sleeve (2), so that the functional section (4) can be stretched and deformed along the axial direction of the anchor rod, and at the same time, the inner wall of the sleeve (2) is squeezed to cause the sleeve (2) to expand and deform; When the sleeve (2) expands and deforms, the sleeve (2) squeezes the surrounding rock of the tunnel in the tangential direction of the tunnel to generate a tangential compression force p r ; The anchor head is arranged at the rear end of the pull rod (6), and after the functional section (4) penetrates the compacted hydrophobic layer (02) along the tunnel radial direction, it is connected to the tray (1) through the anchor head on the pull rod (6).

4. A support structure for a soft rock tunnel with high ground stress and water and mud inrush according to claim 3, characterized in that: The sleeve (2) is provided with a plurality of water-permeable deformation joints (201); the pull rod (6) is a hollow pull rod, and a plurality of small holes are provided on the pull rod (6); pore water in the rock mass of the compacted hydrophobic layer (02) can enter the sleeve (2) along the water-permeable deformation joints (201) and then enter the pull rod (6) through the small holes, and finally be discharged from the rock mass through the drainage port at the rear end of the pull rod (6).

5. A support structure for a soft rock tunnel with high ground stress and water and mud inrush according to claim 4, characterized in that: The water-and-mud-bursting high-stress soft rock tunnel support structure also includes a drainage pipe (8). The outer surface of the rear end of the pull rod (6) is provided with a thread. The pull rod (6) is connected to the drainage pipe (8) through its drainage port and is simultaneously connected to the tray (1) through a nut.

6. A support structure for a soft rock tunnel with high ground stress and sudden water and mud according to claim 5, characterized in that: The pull rod (6) is a smooth variable diameter rod, and the sleeve (2) is also provided with a plurality of deformation guide rails (202) formed by the inner wall thereof protruding inwardly, and the deformation guide rails (202) extend axially along the sleeve (2); The plurality of deformable guide rails (202) are evenly distributed along the radial direction of the sleeve (2), and the protrusion heights of the plurality of deformable guide rails (202) increase from small to large from front to back; When the pull rod (6) is pulled in a direction away from the sleeve (2) and a relative displacement occurs, the protruding deformable guide rail (202) on the inner wall of the sleeve (2) is squeezed outward by the pull rod (6), causing the wall of the sleeve (2) to expand and displace to squeeze the inner wall of the anchor hole, thereby generating a tangential compression force p τ .

7. A method for supporting a soft rock tunnel with high ground stress and water and mud inrush, characterized in that: The method for forming the support structure for a soft rock tunnel with high ground stress caused by sudden water and mud as claimed in any one of claims 1 to 6 comprises the following steps: A. Pre-grouting of tunnel surrounding rock In the rock mass in front of the unexcavated tunnel face, the required tunnel surrounding rock pre-grouting area is determined according to the development of engineering diseases, and pre-grouting is carried out; wherein, after the grouting body is injected, the outer tunnel surrounding rock forms a bonding layer capable of bearing the outer surrounding rock pressure and the original rock groundwater pressure; B. Regionalization of anchor support functions After pre-grouting, the rock mass in front of the tunnel face is excavated according to the designed advance; after excavation, the newly exposed surrounding rock mass and tunnel face are sealed with sprayed concrete, and then the initial support construction of the tunnel is carried out; The initial support construction includes hanging a net, supporting a steel frame, and installing anchor rods; wherein the anchor rods on the inner wall of the tunnel are consistent with the traditional installation method and are distributed in a diamond shape; the anchor rod structure of the anchor rod includes a rod body section (3), and a functional section (4) connected to the rear end of the rod body section (3) and having drainage and expansion deformation functions, the rear end of the functional section (4) is provided with a drainage port, and the rear end of the functional section (4) is provided with an anchor head of the anchor rod structure; After the anchor rod is installed, a certain length of the rod body at the front end of the rod body segment (3) is used as an anchoring segment and is connected to the outer tunnel surrounding rock through an anchoring agent. The anchor head at the rear end acts on the tunnel rock wall through a tray (1). In addition, a plurality of anchored and sealed rod body segments (3) are dispersed in the outer tunnel surrounding rock, so that the outer tunnel surrounding rock forms a reinforced water blocking layer (01) with the function of bearing the outer surrounding rock pressure and blocking water. In addition, a plurality of functional segments (4) are dispersed in the inner tunnel surrounding rock, so that the inner tunnel surrounding rock forms a compacted water-repellent layer (02) with the function of compaction and drainage.

8. A method for supporting a soft rock tunnel with high ground stress and sudden water and mud according to claim 7, characterized in that: Also includes step C: C. Construction completed After the anchor rod structure is installed, the steel frame and shotcrete are constructed, and then the water outlet of the functional section (4) is connected to the drainage pipe (8).

9. A support structure for a soft rock tunnel with high ground stress and water and mud inrush, characterized in that: include: A reinforced water blocking layer (01) is composed of an outer tunnel surrounding rock, a plurality of rod segments (3) dispersed in the outer tunnel surrounding rock, and a grouting body injected into the outer tunnel surrounding rock, and its periphery is in contact with the original rock to bear the outer surrounding rock pressure and the original rock groundwater pressure; A compacted water-repellent layer (02), which is composed of an inner tunnel surrounding rock, a plurality of functional segments (4) dispersed in the inner tunnel surrounding rock, and a grouting body injected into the inner tunnel surrounding rock, and is located inside the reinforced water-blocking layer (01); The functional section (4) and the rod body section (3) are connected in a one-to-one correspondence to form an integral anchor rod structure. The functional section (4) penetrates the compacted hydrophobic layer (02) along the tunnel radial direction. The functional section (4) has drainage and expansion deformation functions. A drainage port is provided at the rear end of the functional section (4). At the same time, an anchor head of the anchor rod structure is provided at the rear end of the functional section (4). The anchor head acts on the tunnel rock wall through the tray (1) and forms a primary support structure with the composite support material outside the tunnel rock wall.

10. A method for supporting a soft rock tunnel with high ground stress and water and mud inrush, characterized in that: The method for forming the water-sudden mud-sudden high-in-situ stress soft rock tunnel support structure according to claim 9 comprises the following steps: A. Pre-grouting of tunnel surrounding rock In the rock mass in front of the unexcavated tunnel face, the required tunnel surrounding rock pre-grouting area is determined according to the development of engineering diseases, and pre-grouting is carried out; wherein, after the grouting body is injected, the outer tunnel surrounding rock forms a bonding layer capable of bearing the outer surrounding rock pressure and the original rock groundwater pressure; B. Regionalization of anchor support functions After pre-grouting, the rock mass in front of the tunnel face is excavated according to the designed advance; after excavation, the newly exposed surrounding rock mass and tunnel face are sealed with sprayed concrete, and then the initial support construction of the tunnel is carried out; The initial support construction includes hanging a net, supporting a steel frame, and installing anchor rods; wherein the anchor rods on the inner wall of the tunnel are consistent with the traditional installation method and are distributed in a diamond shape; the anchor rod structure of the anchor rod includes a rod body section (3), and a functional section (4) connected to the rear end of the rod body section (3) and having drainage and expansion deformation functions, the rear end of the functional section (4) is provided with a drainage port, and the rear end of the functional section (4) is provided with an anchor head of the anchor rod structure; After the anchor rod is installed, a certain length of the rod body at the front end of the rod body segment (3) is used as an anchoring segment and is connected to the outer tunnel surrounding rock through an anchoring agent. The anchor head at the rear end acts on the tunnel rock wall through a tray (1). A plurality of anchored and sealed rod body segments (3) are dispersed in the surrounding rock of the outer tunnel, so that the outer tunnel surrounding rock forms a reinforced water blocking layer (01) with the function of bearing the outer surrounding rock pressure and blocking water. A plurality of functional segments (4) are dispersed in the surrounding rock of the inner tunnel, so that the inner tunnel surrounding rock forms a compacted water-repellent layer (02) with the function of compaction and drainage. After being fixedly installed, the rod body section (3) shall not damage the water blocking performance of the reinforced water blocking layer (01); the functional section (4) is located in the compacted water-repellent layer (02), and its length is consistent with the thickness of the compacted water-repellent layer (02).

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