A tunnel lining structure and construction method for traversing a large, fully filled karst cave

Abstract

The present invention relates to the field of tunnel engineering, and specifically to a tunnel lining structure and construction method for passing through a large fully filled karst cave. The structure includes an initial support and a secondary lining structure, wherein the initial support includes an arch initial support, an upper initial support of a side wall, and a lower initial support of a side wall. Each side of the tunnel is provided with an upper initial support of a side wall, and each side of the tunnel is provided with a lower initial support of a side wall. The structure also includes an arch locking foot anchor, an upper locking foot anchor of a side wall, a lower locking foot anchor of a side wall, and a horizontal anchor, all of which are anchored in the bedrock; the lower ends of both sides of the arch initial support are fixedly connected with arch locking foot anchors, the lower ends of both sides of the upper initial support of the side wall are fixedly connected with upper locking foot anchors of the side wall, the lower ends of both sides of the lower initial support of the side wall are fixedly connected with lower locking foot anchors of the side wall, and the horizontal anchors are fixedly connected with both sides of the initial support. The above structure can control deformation during construction and improve safety.

Description

Technical Field

[0001] The invention relates to a tunnel project, in particular to a tunnel lining structure passing through a large fully-filled karst cave and a construction method. Background Art

[0002] With the rapid development of my country's economy, after entering the 21st century, my country's transportation infrastructure construction has entered a new era, and more and more high-standard railways and highways have been built. At the same time, my country is one of the countries with the largest karst distribution area in the world, especially in Yunnan, Guangxi, Guizhou, and Chongqing. Soluble rock formations such as limestone are widely distributed, and karst is developed. Its scale, shape, size and location are different. In the process of transportation infrastructure construction, a large number of tunnel projects that pass through various types of karst caves inevitably appear, which brings great difficulties to tunnel construction.

[0003] At present, most of the caves that highway and railway tunnels pass through are small and medium-sized empty caves or semi-filled caves, and most of them adopt traditional construction methods such as mortar-laid rubble backfill, bridge structure crossing and ordinary tunnel structure crossing. However, when the tunnel needs to pass through a large fully filled cave with a huge cavity, loose fillings and poor stability, the traditional construction method is difficult to construct, cannot effectively control the deformation of the structure during the construction process, and cannot solve the construction problem of tunnels passing through large fully filled caves. Summary of the invention

[0004] The purpose of the present invention is to provide a tunnel lining structure system and a construction method for passing through a large fully filled karst cave in view of the problems in the prior art that tunnel construction is difficult and deformation of the structure during construction cannot be effectively controlled.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A tunnel lining structure passing through a large fully-filled karst cave comprises an initial support and a secondary lining structure, wherein the initial support comprises an arch initial support, an upper sidewall initial support and a lower sidewall initial support, and each side of the tunnel is provided with an upper sidewall initial support and a lower sidewall initial support, and further comprises an arch locking foot anchor, an upper sidewall locking foot anchor, a lower sidewall locking foot anchor and a horizontal anchor, all of which are anchored in bedrock; the lower ends of both sides of the arch initial support are fixedly connected with the arch locking foot anchor, the lower ends of both sides of the upper sidewall initial support are fixedly connected with the upper sidewall locking foot anchor, the lower ends of both sides of the lower sidewall initial support are fixedly connected with the lower sidewall locking foot anchor, and the horizontal anchor is fixedly connected with both sides of the initial support.

[0007] The tunnel lining structure provided by the present invention that passes through a large fully-filled karst cave has locking anchors arranged below both sides of the initial support of the arch on the initial support, below the upper initial support of the side walls on both sides, and below the lower initial support of the side walls on both sides. During the construction process, after the excavation of the upper step soil is completed, the initial support of the arch is immediately applied, and then the arch locking anchors are applied, and then the excavation of the middle step soil is carried out. After the excavation of the middle step soil is completed, the upper initial support of the side wall located at the edge of the excavation range of the middle step soil is immediately applied, and then the upper locking anchor of the side wall is applied, and then the excavation of the lower step soil is carried out. After the excavation of the lower step soil is completed, the lower initial support of the side wall located at the edge of the excavation range of the lower step soil is immediately applied, and then the lower locking anchor of the side wall is applied. As the tunnel excavation progresses, the initial support structure is gradually constructed, and the arch locking anchors, the upper locking anchors of the side wall, and the lower locking anchors of the side wall are gradually constructed, which effectively control the vertical settlement of the initial support structure during construction and prevent the settlement of the initial support structure from exceeding the designed reserved deformation. On this basis, horizontal anchors are also fixedly connected on both sides of the initial support. During the construction process, the horizontal anchors with the ends anchored in the bedrock are constructed, which can effectively control the horizontal convergence deformation of the side wall during construction and prevent the horizontal convergence deformation of the initial support structure from exceeding the designed reserved deformation.

[0008] As an optional solution of the present invention, the upper locking foot anchor of the side wall and the lower locking foot anchor of the side wall both include jet grouting piles and anchor pipes, and the anchor pipes are arranged in the jet grouting piles.

[0009] As an optional solution of the present invention, the upper initial supports of the side walls on both sides are connected with the horizontal anchors, and the lower initial supports of the side walls on both sides are connected with the horizontal anchors.

[0010] As an optional solution of the present invention, the horizontal anchor is a prestressed anchor cable arranged along the horizontal direction.

[0011] As an optional solution of the present invention, the tunnel lining structure also includes a raft and pile foundations arranged at the bottom of the tunnel, the footings on both sides of the initial support are connected to the raft, the upper end of the pile foundation is fixedly connected to the raft, and the lower end extends to the rock layer at the bottom of the filled cave; the secondary lining is arranged above the raft. The tunnel bottom adopts a pile raft structure, that is, a structure in which the raft and the pile foundation cooperate, and a secondary lining structure is arranged on the raft structure, which can effectively control the structural settlement during operation.

[0012] As an optional solution of the present invention, the tunnel lining structure also includes a water filter layer and a pressure relief pipe, wherein the water filter layer is arranged below the raft, and the lower end of the pressure relief pipe extends into the water filter layer and the upper end extends into the central ditch of the tunnel. The water filter layer is arranged below the raft, and once the groundwater rises during the rainy season, water can be discharged and pressure can be reduced through the pressure relief pipes that connect the water filter layer and the central ditch and are arranged at intervals along the extension direction of the line, thereby avoiding the cracking and bulging of the raft caused by instantaneous high water pressure, and ensuring operational safety.

[0013] As an optional solution of the present invention, the tunnel lining structure also includes a compensating grouting pipe, the upper end of which extends to the surface of the tunnel secondary lining structure and the lower end passes through the pile foundation. Since there are often small beaded caves in the bedrock at the bottom of large-scale filled caves, but they have not been surveyed during construction, under the vibration of train loads during operation, the rock mass at the bottom of the pile foundation may be damaged and settle. Therefore, in order to avoid the destruction of the tunnel bottom structure and excessive deformation of the track structure after the later settlement, a through compensating grouting hole is set vertically in the pile foundation during construction, so that grouting can be supplemented in the later stage.

[0014] In a second aspect, the present invention further provides a construction method for a tunnel lining structure passing through a large fully-filled karst cave, which is used for the above-mentioned tunnel lining structure passing through a large fully-filled karst cave, comprising the following steps:

[0015] S1. Excavate the soil of the upper step, construct the initial support of the arch, and construct the arch foot locking anchors at the arch feet on both sides of the initial support of the arch;

[0016] S2. Excavate the soil of the middle step, construct the primary support of the upper side walls on both sides of the tunnel, and construct the upper side wall locking anchors at the arch feet of the upper side wall primary support on both sides, and construct the horizontal anchors connected to the upper side wall primary support;

[0017] S3. Excavating pile holes for piled raft structures;

[0018] S4. A compensating grouting pipe is embedded in the pile hole, the nozzle of the embedded grouting pipe is located at the bottom elevation of the raft, concrete is poured in the pile hole until the bottom elevation of the raft, and a backfill body is provided on the upper part of the pile hole;

[0019] S5. Excavate the soil of the lower step, construct the lower primary support of the side walls on both sides of the tunnel, and construct the lower locking foot anchors of the side walls at the arch feet of the lower primary support of the side walls on both sides, and construct the horizontal anchors connected to the lower primary support of the side walls;

[0020] S6. Extend the compensating grouting pipe to the designed elevation, construct a water filter layer, bury a pressure relief pipe, and construct a raft slab connected to the pile foundation;

[0021] S7. Construct the U-shaped bottom plate at the bottom of the secondary lining structure;

[0022] S8. Construct a central ditch to connect the pressure relief pipe with the central ditch;

[0023] S9. Secondary lining of formwork arch wall.

[0024] The above-mentioned construction method provided by the present invention gradually sets the arch locking foot anchor, the upper locking foot anchor of the side wall and the lower locking foot anchor of the side wall as the excavation process proceeds, and also sets the horizontal anchor during the excavation, so that the vertical settlement and horizontal deformation of the tunnel can be well controlled during the construction process, thereby effectively ensuring the construction safety. Secondly, with the traditional construction method, it is necessary to excavate to the bottom of the tunnel, that is, after the three steps are excavated, the pile foundation is applied, but due to the long time of pile foundation construction, it will lead to a long time that the secondary lining cannot be applied, and the tunnel passes through the fully filled karst cave, the surrounding rock bearing capacity is low, the surrounding rock load is large, and it depends on the initial support for a long time, which is high in risk. Once deformation, cracking or even collapse occurs, it will cause immeasurable losses to the pile foundation construction personnel and machinery. Therefore, after the middle step is excavated, the present invention makes full use of the middle step platform to carry out pile foundation construction in advance, which can not only save time, but also avoid the high risk of not applying the secondary lining for a long time after the entire tunnel is excavated.

[0025] As an optional solution of the present invention, in the step S2, at least two horizontal anchors spaced apart in the height direction are provided on the initial support of the upper portion of the side wall on each side;

[0026] In the step S5, at least one horizontal anchor is provided on the initial support at the lower portion of each side wall.

[0027] As an optional solution of the present invention, after the step S8 is completed and before the step S9 is performed, the following steps are further included:

[0028] S81. Lay arch wall drainage system.

[0029] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0030] 1. The tunnel lining structure provided by the present invention that passes through a large fully filled karst cave has locking foot anchors arranged below both sides of the initial support of the arch on the initial support, below the initial support of the upper part of the side walls on both sides, and below the initial support of the lower part of the side walls on both sides. As the construction process proceeds, locking foot anchors are gradually arranged at different positions, which can control the settlement of the tunnel in the vertical direction during the construction process;

[0031] 2. The tunnel lining structure provided by the present invention that passes through a large fully filled karst cave has horizontal anchors on both sides of its initial support. During construction, the horizontal anchors can be used to control the horizontal deformation of the tunnel during the construction process.

[0032] 3. The pile raft structure is set at the bottom of the tunnel to effectively control the settlement during the operation of the tunnel;

[0033] 4. Compensation grouting pipes are set on the pile foundation of the pile raft structure. If there are unexplored small bead-like karst caves at the bottom of the tunnel, which causes settlement during tunnel operation, safety can also be ensured by compensating grouting;

[0034] 5. A water filter layer is set at the bottom of the raft to avoid safety hazards caused by rising groundwater during rainy seasons;

[0035] 6. The construction method of the tunnel lining structure passing through a large fully-filled karst cave provided by the present invention can better control the vertical settlement and horizontal deformation of the tunnel during construction, and can effectively ensure the construction safety. Secondly, since the pile foundation is constructed immediately after the excavation of the middle step soil, it can effectively avoid the high risk of not constructing the secondary lining for a long time after the tunnel excavation due to waiting for the pile foundation construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic structural diagram of a tunnel lining structure passing through a large fully-filled cave provided in Example 1 of the present invention.

[0037] Figure 2 It is a schematic diagram of the construction method provided in Example 2 of the present invention at step S1.

[0038] Figure 3 It is a schematic diagram of the construction method provided in Example 2 of the present invention at step S2.

[0039] Figure 4 It is a schematic diagram of the construction method provided in Example 2 of the present invention at step S2.

[0040] Figure 5 It is a schematic diagram of the construction method provided in Example 2 of the present invention at step S3.

[0041] Figure 6 It is a schematic diagram of the construction method provided in Example 2 of the present invention at step S4.

[0042] Figure 7 It is a schematic diagram of the construction method provided in Example 2 of the present invention at step S5.

[0043] Figure 8 It is a schematic diagram of the construction method provided in Example 2 of the present invention at step S5.

[0044] Fig. 9 It is a schematic diagram of the construction method provided in Example 2 of the present invention at step S7.

[0045] Fig.10It is a schematic diagram of the construction method provided in Example 2 of the present invention at step S7.

[0046] Fig.11 It is a schematic diagram of the construction method provided in Example 2 of the present invention at step S8.

[0047] Icons: 1-upper step soil; 2-middle step soil; 3-lower step soil; 10-large pipe shed advance support; 20a-arch initial support; 20b-upper side wall initial support; 20c-lower side wall initial support; 203-grouting anchor pipe; 21-arch locking anchor; 22-upper side wall locking anchor; 22a-anchor pipe; 22b-jet grouting pile; 23-lower side wall locking anchor; 24-temporary Inverted arch; 24a-temporary shotcrete layer; 24b-temporary steel frame; 32-horizontal anchor; 401-raft; 402-pile foundation; 405-compensation grouting pipe; 403-pile hole; 404-earth-rock backfill; 601-secondary lining of arch wall; 602-U-shaped bottom plate; 70-upper filling of bottom plate; 80-drainage system; 90-filtration layer; 100-pressure relief pipe; 0a-filling; 0b-bedrock. DETAILED DESCRIPTION

[0048] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0049] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0050] Example 1

[0051] See also Figure 1 The embodiment of the present invention provides a tunnel lining structure for passing through a large fully filled cave, which is suitable for a tunnel passing through a large fully filled cave. The outside of the filled cave is bedrock 0b, the filling material 0a is filled in the cavity of the bedrock 0b, and the tunnel passes through the filling material 0a.

[0052] The tunnel lining structure includes an arch large pipe shed advance support 10, an initial support, a drainage system 80 and a secondary lining structure.

[0053] The initial support includes an arch initial support 20a, a side wall upper initial support 20b and a side wall lower initial support 20c. An upper side wall initial support 20b is provided on each side of the tunnel, one of which is the left wall upper initial support 20b, and the other is the right wall upper initial support 20b. A lower side wall initial support 20c is provided on each side of the tunnel, one of which is the left wall lower initial support 20c, and the other is the right wall lower initial support 20c.

[0054] The lower ends of the left and right sides of the arch initial support 20a are both fixedly connected with the arch locking foot anchor 21. The lower end of the left wall upper initial support 20b is fixedly connected with the side wall upper locking foot anchor 22, and the lower end of the right wall upper initial support 20b is also fixedly connected with the side wall upper locking foot anchor 22. The lower end of the left wall lower initial support 20c is fixedly connected with the side wall lower locking foot anchor 23, and the lower end of the right wall lower initial support 20c is also fixedly connected with the side wall lower locking foot anchor 23.

[0055] The ends of the arch locking foot anchor 21, the side wall upper locking foot anchor 22, and the side wall lower locking foot anchor 23 away from the initial support are all anchored in the bedrock 0b. The arch locking foot anchor 21 is a locking foot anchor pipe, and the side wall upper locking foot anchor 22 and the side wall lower locking foot anchor 23 each include an oblique jet grouting pile 22b and an anchor pipe 22a, wherein the anchor pipe 22a is placed in the oblique jet grouting pile 22b.

[0056] Two horizontal anchors 32 are also connected to the upper initial support 20b of the left wall, and the two horizontal anchors 32 are spaced apart in the vertical direction. Two horizontal anchors 32 are also connected to the upper initial support 20b of the right wall, and the two horizontal anchors 32 are spaced apart in the vertical direction. A horizontal anchor 32 is connected to the lower initial support 20c of the left wall. A horizontal anchor 32 is also connected to the lower initial support 20c of the right wall. The ends of each horizontal anchor 32 away from the initial support are anchored in the bedrock 0b. Among them, the horizontal anchors 32 are prestressed anchor cables.

[0057] Further, each part of the initial support includes a steel frame, shotcrete, and a grouting anchor pipe 203 anchored in the filler 0a. The arch locking foot anchor 21 is arranged at the steel frame foundation of the arch initial support 20a, the side wall upper locking foot anchor 22 is arranged at the steel frame foundation of the side wall upper initial support 20b, and the side wall lower locking foot anchor 23 is arranged at the steel frame foundation of the side wall lower initial support 20c.

[0058] A raft 401 and pile foundation 402 are provided at the bottom of the tunnel, and the footings on both sides of the initial support are connected to the raft 401. The upper end of the pile foundation 402 is fixedly connected to the lower surface of the raft 401, and the lower end of the pile foundation 402 extends to the rock layer at the bottom of the cave. The secondary lining structure is arranged above the raft 401. The pile foundations 402 are arranged at intervals along the length and transverse directions of the tunnel, and a compensating grouting pipe 405 is also provided in the pile foundation 402. The upper end of the compensating grouting pipe 405 extends to the secondary lining surface, and the lower end runs through the entire pile foundation 402.

[0059] A water filter layer 90 and a pressure relief pipe 100 are also provided below the raft 401. The water filter layer 90 is filled with gravel. The lower end of the pressure relief pipe 100 is located in the water filter layer 90, and the upper end is connected to the central ditch of the tunnel.

[0060] The secondary lining structure includes an arch wall secondary lining 601 and a U-shaped bottom plate 602. The U-shaped bottom plate 602 is located above the raft 401.

[0061] The beneficial effects of the tunnel lining structure passing through a large fully filled cave provided by the embodiment of the present invention are:

[0062] 1. The tunnel lining structure provided by the present invention that passes through a large fully filled karst cave has locking foot anchors arranged below both sides of the arch initial support 20a on the initial support, below the upper initial support 20b of the side walls on both sides, and below the lower initial support 20c of the side walls on both sides. As the construction process proceeds, locking foot anchors are gradually arranged at different positions, which can control the settlement of the tunnel in the vertical direction during the construction process;

[0063] 2. The tunnel lining structure provided by the present invention that passes through a large fully filled karst cave has horizontal anchors 32 disposed on both sides of the initial support. During construction, the horizontal anchors 32 are applied to control the horizontal deformation of the tunnel during the construction process.

[0064] 3. A pile raft structure is set at the bottom of the tunnel, i.e. a structure in which the pile foundation 402 is connected to the raft 401, which can effectively control the settlement during the operation of the tunnel;

[0065] 4. A compensating grouting pipe 405 is provided on the pile foundation 402 of the pile raft structure. If there are unsurveyed small bead-like karst caves at the bottom of the tunnel, which causes settlement during tunnel operation, compensating grouting can also be used to ensure safety;

[0066] 5. A water filter layer 90 is provided at the bottom of the raft 401 to avoid potential safety hazards caused by rising groundwater during rainy seasons.

[0067] Example 2

[0068] The embodiment of the present invention provides a construction method for a tunnel lining structure passing through a large fully filled karst cave, which is used to construct the tunnel lining structure passing through a large fully filled karst cave described in Example 1, and includes the following steps:

[0069] S0. Advance support steps;

[0070] Specifically, the advance support step includes applying the arch large pipe shed advance support 10. In this embodiment, the φ108mm pipe shed advance support is applied.

[0071] S1.Please refer to Figure 2 , excavate the upper step soil 1, construct the arch initial support 20a, and construct the arch locking foot anchors 21 at the foundations on both sides of the arch initial support 20a;

[0072] In this embodiment, the arch locking foot anchor 21 is a φ76 locking foot anchor tube.

[0073] S2. Please refer to Figure 3 and Figure 4 , excavate the middle step soil 2, construct the upper initial support 20b of the side wall on both sides of the tunnel, and construct the upper locking anchors 22 of the side wall at the foundation of the upper initial support 20b of the side wall on both sides, and construct the horizontal anchors 32 connected to the upper initial support 20b of the side wall;

[0074] Specifically, the middle step soil 2 is excavated along the tunnel longitudinal lag of the upper step face for a distance, and immediately after the excavation, the corresponding left wall upper initial support 20b, right wall upper initial support 20b and temporary invert 24 are constructed. The temporary invert 24 includes a temporary steel frame 24b and a temporary shotcrete layer 24a. The upper side wall locking foot anchor 22 is constructed for the upper left wall initial support 20b as a reinforcement measure, and the upper side wall locking foot anchor 22 is constructed for the upper right wall initial support 20b as a reinforcement measure.

[0075] The locking foot anchor 22 on the upper side wall includes an oblique jet grouting pile 22b and an anchor pipe 22a. The anchor pipe 22a is placed in the oblique jet grouting pile 22b, and the anchor pipe 22a is a φ76 steel pipe.

[0076] The horizontal anchor 32 is arranged in the horizontal direction, one end of which is connected to the initial support 20b of the upper side wall, and the other end is anchored in the bedrock 0b. The upper side wall initial support 20b on the left and right sides of the tunnel are both connected with the horizontal anchor 32.

[0077] S3. Please refer to Figure 5 , excavating pile holes 403 of the piled raft structure;

[0078] Specifically, a pile hole 403 of the piled raft structure is excavated on the middle step;

[0079] S4. Please refer to Figure 6 , pre-buried a compensation grouting pipe 405 in the pile hole 403, the pipe mouth of the compensation grouting pipe 405 is located at the bottom elevation of the raft 401, concrete is poured in the pile hole 403 until the bottom elevation of the raft 401, and a backfill body is arranged on the upper part of the pile hole 403;

[0080] Specifically, after the excavation of the pile hole 403 is completed, a compensating grouting pipe 405 is pre-buried in the pile hole 403, the pipe mouth of the pre-buried grouting pipe is located at the bottom elevation of the raft 401, and the upper end of the pre-buried grouting pipe is sealed, and then concrete is poured into the pile hole 403 to the bottom elevation of the raft 401. After the concrete is finally set, an earth and stone backfill body 404 is set in the upper part of the pile hole 403.

[0081] S5.Please refer to Figure 7 and Figure 8, excavate the lower step soil 3, construct the lower initial support 20c of the side walls on both sides of the tunnel, and construct the lower locking foot anchors 23 of the side walls at the foundation of the lower initial support 20c of the side walls on both sides, and construct the horizontal anchors 32 connected to the lower initial support 20c of the side walls;

[0082] Specifically, the lower step soil 3 is excavated along the longitudinal lag of the middle step heading face of the tunnel for a distance, and the corresponding left wall lower initial support 20c and right wall lower initial support 20c are immediately applied after excavation, and the side wall lower locking foot anchor 23 is applied to the foundation of the left wall lower initial support 20c, and the side wall lower locking foot anchor 23 is applied to the foundation of the right wall lower initial support 20c.

[0083] The locking foot anchor 23 at the lower part of the side wall comprises an oblique jet grouting pile 22b and an anchor pipe 22a. The anchor pipe 22a is placed in the oblique jet grouting pile 22b and is a φ76 steel pipe.

[0084] Horizontal anchors 32 are connected to the lower initial supports 20c of the side walls on the left and right sides of the tunnel.

[0085] In this embodiment, the horizontal anchor 32 is an anchor cable.

[0086] S6.Please refer to Fig. 9 , extend the compensation grouting pipe 405 to the designed elevation, construct a water filter layer 90, pre-bury a pressure relief pipe 100, and construct a raft 401 connected to the pile foundation 402;

[0087] Specifically, constructing the water filter layer 90 includes excavating the soil at the water filter layer 90 and then filling the water filter layer 90 with crushed stones.

[0088] S7.Please refer to Fig. 9 and Fig.10 , construct a U-shaped bottom plate 602 at the lower part of the secondary lining structure;

[0089] S8.Please refer to Fig.11 , construct a central water ditch so that the pressure relief pipe 100 is connected to the central water ditch;

[0090] Specifically, after the concrete of the U-shaped bottom plate 602 is initially set, the upper portion of the bottom plate is filled 70 to a designed height, a central ditch is constructed, and the pressure relief pipe 100 is introduced into the central ditch.

[0091] S81.Please refer to Figure 1 , laying arch wall drainage system 80.

[0092] S9.Please refer to Figure 1 , secondary lining of molded arch wall 601.

[0093] Specifically, the one-time mold-built arch wall secondary lining 601. After step S9 is completed, the following steps are also included:

[0094] S10. Construction of side ditches, cable trenches and other ancillary works.

[0095] Repeat the above steps S0-S10 until the full length excavation of the tunnel section designed for this construction method is completed.

[0096] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A construction method for a tunnel lining structure passing through a large fully-filled karst cave, used for constructing a tunnel lining structure passing through a large fully-filled karst cave, the tunnel lining structure passing through a large fully-filled karst cave comprising an initial support and a secondary lining structure arranged from the inside to the outside, the initial support comprising an arch initial support (20a), an upper initial support of a side wall (20b) and a lower initial support of a side wall (20c), each side of the tunnel is provided with an upper initial support of a side wall (20b), and each side of the tunnel is provided with a lower initial support of a side wall (20c), characterized in that: It also includes an arch locking anchor (21), a side wall upper locking anchor (22), a side wall lower locking anchor (23) and a horizontal anchor (32), all of which are anchored into the bedrock (0b); The lower ends of both sides of the arch initial support (20a) are fixedly connected to the arch locking foot anchors (21), the lower ends of both sides of the side wall upper initial support (20b) are fixedly connected to the side wall upper locking foot anchors (22), the lower ends of both sides of the side wall lower initial support (20c) are fixedly connected to the side wall lower locking foot anchors (23), and both sides of the initial support are fixedly connected to the horizontal anchors (32); the side wall upper locking foot anchors (22) and the side wall lower locking foot anchors (23) each comprise a jet grouting pile (22b) and an anchor pipe (22a), and the anchor pipe (22a) is arranged in the jet grouting pile (22b); The upper initial supports (20b) of the side walls on both sides are connected to the horizontal anchors (32), and the lower initial supports (20c) of the side walls on both sides are connected to the horizontal anchors (32); the horizontal anchors (32) are prestressed anchor cables arranged in the horizontal direction; It also includes a raft (401) and a pile foundation (402) arranged at the bottom of the tunnel, the wall footings on both sides of the initial support are connected to the raft (401), the upper end of the pile foundation (402) is fixedly connected to the raft (401), and the lower end extends to the bottom bedrock (0b) of the filled cave; The secondary lining structure is arranged above the raft (401); It also includes a water filter layer (90) and a pressure relief pipe (100), wherein the water filter layer (90) is arranged below the raft (401), and the lower end of the pressure relief pipe (100) extends into the water filter layer (90) and the upper end extends into the central groove of the tunnel; It also includes a compensating grouting pipe (405), the upper end of which extends to the surface of the tunnel secondary lining structure and the lower end of which passes through the pile foundation (402); The following steps are involved: S1. Excavate the soil of the upper step, construct the initial arch support (20a), and construct the arch locking anchors (21) at the foundations on both sides of the initial arch support (20a); S2. Excavate the soil of the middle step, construct the upper initial support (20b) of the side walls on both sides of the tunnel, construct the upper locking anchors (22) of the side walls at the base of the upper initial support (20b) of the side walls on both sides, and construct the horizontal anchors (32) connected to the upper initial support (20b) of the side walls; S3. excavating a pile hole (403) of the piled raft structure; S4. A compensating grouting pipe (405) is embedded in the pile hole (403), the port of which is located at the bottom elevation of the raft (401), concrete is poured into the pile hole (403) until the bottom elevation of the raft (401), and a backfill body is arranged on the upper part of the pile hole (403); S5. Excavate the soil of the lower step, construct the lower initial support (20c) of the side walls on both sides of the tunnel, construct the lower locking foot anchors (23) of the side walls at the arch feet of the lower initial support (20c) of the side walls on both sides, and construct the horizontal anchors (32) connected to the lower initial support (20c) of the side walls; S6. Extend the compensating grouting pipe (405) to the designed elevation, construct a water filter layer (90), pre-embed the pressure relief pipe (100), construct a raft (401) and connect it to the pile foundation (402); S7. construct a U-shaped bottom plate (602) at the lower part of the secondary lining structure; S8. construct a central water ditch so that the pressure relief pipe (100) is connected to the central water ditch; S9. Secondary lining of form-cast arch wall (601).

2. The construction method of a tunnel lining structure passing through a large fully filled karst cave according to claim 1, characterized in that: In the step S2, at least two horizontal anchors (32) spaced apart in the height direction are provided on the upper initial support (20b) of the side wall on each side; In the step S5, at least one horizontal anchor (32) is provided on the lower initial support (20c) of each side wall.

3. The construction method of a tunnel lining structure passing through a large fully filled karst cave according to claim 1, characterized in that: After step S8 is completed and before step S9 is performed, the following steps are further included: S81. Lay the arch wall drainage system (80).

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