Primary support structure for soft rock large-deformation tunnel

Abstract

The utility model discloses a primary support structure for a soft rock large deformation tunnel, which comprises a lining and a reinforced secondary lining, the outer side of the lining is abutted against the surrounding rock of the tunnel, and the reinforced secondary lining is constructed on the inner side of the lining, so that a grouting gap is reserved between the lining and the reinforced secondary lining; one end of a connecting steel bar is pre-embedded in the inner side of the lining and extends out of the lining, the extending end of the connecting steel bar penetrates through the grouting gap and is pre-embedded in the outer side of the reinforced secondary lining, and connecting mortar is injected into the grouting gap to form a mortar connecting layer. The supporting structure is divided into the lining on the outer side, the reinforcing secondary lining on the inner side and the cement mortar connecting layer in the middle, the peripheral side of the tunnel can be rapidly supported, the suspension time is shortened, surrounding rock can be supported, the influence of the reinforcing secondary lining on deformation of the surrounding rock can be reduced through shrinkage of the connecting layer, and the supporting effect is good. Therefore, the service life of the whole supporting structure is prolonged.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of initial support structure for soft rock large deformation tunnel, belong to tunnel excavation support system technical field. BACKGROUND

[0002] Soft rock is a kind of complex rock mechanics medium with significant plastic deformation under specific environment. According to its characteristics and the mechanism of plastic deformation, soft rock can be divided into four categories: expansive soft rock, high stress soft rock, jointed soft rock and composite soft rock. Tunnel is a kind of engineering building buried in stratum, a form of human use of underground space, mainly divided into traffic tunnel, water tunnel, municipal tunnel, mine tunnel and military tunnel. Soft rock tunnel refers to the tunnel composed of soft rock or soil layer. These rocks or soil layers usually have low compressive strength and high deformability, so special design and construction technology is needed to ensure its safety and stability. In soft rock tunnel engineering, geological characteristics, mechanical properties and appropriate support measures are key considerations.

[0003] The excavation and support of soft rock tunnel are relatively difficult, and certain technical measures and support measures need to be taken to ensure the safety and stability of the tunnel. Currently, the initial support is replaced in the form of arch frame after large deformation, which has long construction period, high cost and high safety risk. At the same time, when the tunnel is excavated in steps, the tunnel deformation gradually increases with the excavation progress, the radius of the surrounding rock loose circle gradually increases, and the initial support pressure gradually increases, which will have adverse effects on the deformation of the initial support. In order to effectively protect the stability of soft rock tunnel, it is necessary to design an initial support structure for soft rock large deformation tunnel to protect the stability of surrounding rock. SUMMARY

[0004] In order to effectively protect the stability of soft rock tunnel, the utility model provides an initial support structure for soft rock large deformation tunnel, which prolongs the service life of the support structure under the premise of protecting the stability of surrounding rock.

[0005] The technical scheme of the utility model is as follows:

[0006] The utility model provides an initial support structure for soft rock large deformation tunnel, which includes inner lining 1-1 and reinforced secondary lining 1-2. The outer side of the inner lining 1-1 is in abutment with the surrounding rock of the tunnel. The reinforced secondary lining 1-2 is made on the inner side of the inner lining 1-1, so that a grouting gap 1-3 is left between the inner lining 1-1 and the reinforced secondary lining 1-2. One end of the connecting steel bar is pre-buried in the inner side of the inner lining 1-1 and extends out from the inner lining 1-1. The extending end of the connecting steel bar passes through the grouting gap 1-3 and is pre-buried in the outer side end of the reinforced secondary lining 1-2. Connection mortar is injected into the grouting gap 1-3 to form a mortar connection layer.

[0007] Further, the end of the arch-shaped primary support structure formed by the inner lining 1-1, the reinforced secondary lining 1-2 and the mortar connecting layer is connected with one end of the vertical adjusting device 3 through a steel plate support 4, and the other end of the vertical adjusting device 3 is installed with another steel plate support 4.

[0008] Further, the adjacent primary support structures 1 are connected through the longitudinal connecting rods 2.

[0009] Further, a plurality of grouting holes 5 are formed in the surrounding rock of the tunnel, one end of the anchor cable 6 is inserted into the grouting hole 5 and pressure grouting is performed, and the other end of the anchor cable 6 is pulled out from the grouting hole 5; the inner lining 1-1 is provided with a pre-formed hole corresponding to the position where the anchor cable 6 is pulled out, and the end of the anchor cable 6 pulled out from the grouting hole 5 is pulled through the hole.

[0010] Further, the grouting hole 5 is inclinedly arranged at an angle of 30° to 60° towards the inside of the surrounding rock.

[0011] The beneficial effects of the utility model are:

[0012] The support structure of the utility model is divided into the inner lining on the outside, the reinforced secondary lining on the inside and the cement mortar connecting layer in the middle, can quickly support the tunnel periphery, reduces the time in the air, can support the surrounding rock, can reduce the influence of the reinforced secondary lining on the deformation of the surrounding rock through the shrinkage of the connecting layer, thereby prolongs the service life of the whole support structure; further, the adjacent primary support structures are connected through the longitudinal connecting rods, and cooperate with the punching and grouting, can significantly improve the overall stress performance of the arch frame, effectively controls the deformation of the primary support structure; and the anchor cables of the steel wire ropes are connected by mutual torsion, can enhance the combination strength with the mortar structure, and further improves the stability of the surrounding rock structure through the oblique insertion. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 The structure schematic view of the primary support structure is provided for the utility model;

[0014] Figure 2 The schematic view of the adjacent primary support structures connected through the longitudinal connecting rods;

[0015] Figure 3 The installation schematic view of the vertical deformation device;

[0016] Figure 4 The side schematic view of the water guide groove and the surrounding rock structure;

[0017] The numbers in the drawing are: 1, primary support structure; 1-1, inner lining; 1-2, reinforced secondary lining; 1-3, grouting gap; 2, longitudinal connecting rod; 3, vertical adjusting device; 4, steel plate support; 5, grouting hole; 6, anchor cable; 7, water guide groove. DETAILED DESCRIPTION

[0018] The utility model will be further described below with reference to the accompanying drawings and embodiments, but the scope of the utility model is not limited to the description.

[0019] Example 1: As Figures 1-4 As shown, an initial support structure for a soft rock tunnel with large deformation includes an inner lining 1-1 and a reinforced secondary lining 1-2. The outer side of the inner lining 1-1 abuts against the surrounding rock of the tunnel. The reinforced secondary lining 1-2 is constructed on the inner side of the inner lining 1-1, leaving a grouting gap 1-3 between the inner lining 1-1 and the reinforced secondary lining 1-2. One end of a connecting steel bar is pre-embedded in the inner end of the inner lining 1-1 and extends out of the inner lining 1-1. The extended end of the connecting steel bar passes through the grouting gap 1-3 and is pre-embedded in the outer end of the reinforced secondary lining 1-2. Connecting mortar is injected into the grouting gap 1-3 to form a mortar connection layer.

[0020] Furthermore, at the ends of the arched initial support structure formed by the inner lining 1-1, the reinforced secondary lining 1-2, and the mortar connection layer, a steel plate support 4 is connected to one end of the vertical adjustment device 3, and another steel plate support 4 is installed at the other end of the vertical adjustment device 3. For example, the vertical adjustment device is a screw jack.

[0021] Furthermore, adjacent initial support structures 1 are connected by longitudinal connecting rods 2.

[0022] Furthermore, multiple grouting holes 5 are made in the surrounding rock of the tunnel. One end of the anchor cable 6 is inserted into the grouting hole 5 and pressurized grouting is performed. The other end of the anchor cable 6 passes out from the grouting hole 5.

[0023] Furthermore, the inner lining 1-1 is pre-drilled with a clearance hole corresponding to the position where the anchor cable 6 passes through. One end of the anchor cable 6 that passes through the grouting hole 5 is passed through the clearance hole and tightened.

[0024] The construction process of the optional initial support structure for soft rock tunnels with large deformation is given below:

[0025] S1. Allow reasonable allowance for settlement and deformation of the surrounding rock in the early stage of excavation;

[0026] S2. Drilling and grouting: The equipment drills multiple grouting holes 5 into the surrounding rock of the tunnel. After the grouting holes 5 are drilled, pressure grouting is performed.

[0027] S3. Install the prefabricated initial support structure 1.

[0028] S4: A vertical adjustment device 3 is installed at the end of the initial support structure 1 through a steel plate support 4. After the initial support structure 1 settles and deforms, the vertical adjustment device 3 is used to adjust the vertical deformation.

[0029] S5: connecting the adjacent primary support structures 1 through the longitudinal connecting rods 2.

[0030] In the technical solution, the surrounding rock structure is reinforced by drilling and grouting to reduce the possibility of surrounding rock sliding, and then the primary support structure 1 is installed to quickly support the periphery of the tunnel and reduce the suspension time of the periphery of the tunnel.

[0031] Specifically, the method of reasonably reserving the surrounding rock settlement deformation in S1 is as follows: according to the deformation characteristics of soft rock and specific geological conditions, combined with the geological exploration report and design drawings, the expected settlement deformation of the surrounding rock is determined. In the pre-construction stage, the size and form of the primary support structure are reasonably determined according to the predicted data and actual situation to fully reserve the deformation space. During the specific construction, the upper 1 / 2 of the tunnel can be excavated from top to bottom first, and after the excavation is completed, the water guide groove 7 is placed on the surface of the excavated tunnel 1 / 2, and the water is concentrated and guided to the containing place through the water guide groove 7. The water seeping out of the inner wall of the tunnel can be guided to the pre-set containing place to reduce the interference of seepage water on tunnel construction.

[0032] Specifically, the step S2 includes:

[0033] S21: drilling: the positions, number, depth and spacing of the grouting holes 5 are determined according to the design requirements and the surrounding rock conditions, the equipment is directed towards the interior of the surrounding rock to perform drilling work to obtain a plurality of grouting holes 5, and the grouting holes 5 are inclinedly arranged at an angle of 30° to 60° towards the interior of the surrounding rock; it should be noted that the same angle is designed for all the grouting holes 5 when the same tunnel surrounding rock is constructed;

[0034] S22: anchor cable 6 reinforcement: the anchor cable 6 is inserted into the pre-drilled grouting hole 5 according to the design requirements and is preliminarily fixed;

[0035] S23: grouting and solidification: the grouting hole 5 with the inserted anchor cable 6 is filled with the grouting material in a pressure grouting manner according to the design requirements, and the grouting material in the grouting hole is fully solidified.

[0036] In the technical solution, after the drilling of the grouting hole 5 is completed, the anchor cable 6 is first inserted into the grouting hole 5, and then pressure grouting is performed, which can further improve the reinforcement effect of the surrounding rock structure. By obliquely inserting the grouting hole 5 at an angle of 30° to 60°, the reinforcement effect of the grouting structure in the grouting hole 5 on the surrounding rock is further improved.

[0037] Further, the anchor cable used should meet the design requirements, including a plurality of steel wire ropes connected by mutual torsion. The bending characteristics of the steel wire rope and the mutual torsion connection of the steel wire rope can increase the bonding strength of the steel wire rope and the mortar structure, and the oblique insertion can further improve the stability of the surrounding rock structure.

[0038] Specifically, the step S3 includes:

[0039] S31: Installation of Lining 1-1: The prefabricated lining 1-1 is installed on the sidewall and top of the tunnel, with the outer side of the lining 1-1 abutting against the surrounding rock; the lining 1-1 is pre-drilled with clearance holes corresponding to the positions where the anchor cables pass through. After the lining is installed, the anchor cable 6 is passed through the clearance hole and tightened, so that it applies tension to the side of the lining 1-1 facing the surrounding rock, and the anchor cable 6 plays a further role in fixing the lining 1-1.

[0040] S32: Installation of reinforced secondary lining 1-2: Reinforced secondary lining 1-2 is installed on the inner side of inner lining 1-1, so that there is a grouting gap 1-3 between inner lining 1-1 and reinforced secondary lining 1-2, and connecting steel bars are pre-embedded on the inner side of inner lining 1-1 and the outer side of reinforced secondary lining 1-2, and the connecting steel bars extend into the grouting gap 1-3.

[0041] S33: Grouting reinforcement: Inject connecting mortar into the grouting gaps 1-3 using pressurized grouting until the mortar solidifies.

[0042] This utility model divides the initial support structure 1 into an outer inner lining 1-1 and a reinforced secondary lining 1-2, and a grouting gap 1-3 formed by connecting mortar in the middle. It can not only effectively support the surrounding rock, but also reduce the influence of the reinforced secondary lining 1-2 on the deformation of the surrounding rock through the shrinkage of the grouting gap 1-3.

[0043] Specifically, S4 is as follows: according to the design drawings, the ends of the initial support structure 1 are connected to one end of the vertical adjustment device 3 by steel plate supports 4, and a steel plate support 4 is installed at the other end of the vertical adjustment device 3. The steel plate support 4 can be used to reduce the settlement of the vertical adjustment device during the vertical deformation compensation process.

[0044] Specifically, S5 involves using longitudinal connecting rods 2 to connect the newly installed initial support structure 1 arranged longitudinally to the existing initial support structure 1. The longitudinal connection distance between any two adjacent initial support structures 1 is no greater than the distance between the two ends of a single initial support structure 1. In the above technical solution, adjacent initial support structures 1 are connected by longitudinal connecting rods 2, which improves the overall stability of the initial support structure. The tunnel ground corresponding to the bottom of the vertical adjustment device remains flat, making the connection of the vertical adjustment device more stable.

[0045] By adopting the above technical solutions, and based on the deformation characteristics of soft rock and specific geological conditions, combined with the geological survey report and design drawings, the expected settlement and deformation of the surrounding rock are determined. In the pre-construction stage, based on predicted data and actual conditions, the size and form of the initial support structure are rationally determined to fully reserve deformation space. The location, number, depth, and spacing of grouting holes should be determined according to design requirements and surrounding rock conditions. Drilling operations must be carried out towards the interior of the surrounding rock, with the grouting holes inclined between 30° and 60°. Anchor cables should be inserted into the pre-drilled grouting holes and initially fixed according to design requirements. Pressure grouting is used to inject the designed grouting material into the grouting holes until fully cured. The prefabricated lining is installed on the sidewalls and top of the tunnel, ensuring its outer side abuts against the surrounding rock. A reinforced secondary lining is constructed on the inner side of the lining, leaving grouting gaps and pre-embedded connecting steel bars. Connecting mortar is injected into the grouting gaps through pressurized grouting until it solidifies. According to the design drawings, a vertical adjustment device of the required type is installed at the bottom of the initial support structure. The bottom is supported by steel plates to reduce the settlement of the adjustment device during the vertical deformation compensation process. The newly installed arch-type initial support structure is longitudinally connected to the existing steel arch-type initial support structure using longitudinal connecting rods 2 made of steel sections. At the same time, the longitudinal connection spacing is not greater than the spacing between the two ends of a single initial support structure 1 to ensure reliable connection.

[0046] The specific embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. An initial support structure for tunnels with large deformation in soft rock, characterized in that, The system includes an inner lining (1-1) and a reinforced secondary lining (1-2). The outer side of the inner lining (1-1) abuts against the surrounding rock of the tunnel. The reinforced secondary lining (1-2) is constructed on the inner side of the inner lining (1-1), leaving a grouting gap (1-3) between the inner lining (1-1) and the reinforced secondary lining (1-2). One end of a connecting steel bar is pre-embedded in the inner end of the inner lining (1-1) and extends out of the inner lining (1-1). The extended end of the connecting steel bar passes through the grouting gap (1-3) and is pre-embedded in the outer end of the reinforced secondary lining (1-2). Connecting mortar is injected into the grouting gap (1-3) to form a mortar connection layer.

2. The initial support structure for soft rock tunnels with large deformation according to claim 1, characterized in that, At the ends of the arched initial support structure formed by the inner lining (1-1), the reinforced secondary lining (1-2), and the mortar connection layer, a steel plate support (4) is connected to one end of the vertical adjustment device (3), and another steel plate support (4) is installed at the other end of the vertical adjustment device (3).

3. The initial support structure for soft rock tunnels with large deformation according to claim 1, characterized in that, Adjacent initial support structures (1) are connected by longitudinal connecting rods (2).

4. The initial support structure for soft rock tunnels with large deformation according to claim 1, characterized in that, Multiple grouting holes (5) are made in the surrounding rock of the tunnel. One end of the anchor cable (6) is inserted into the grouting hole (5) and grouting is performed under pressure. The other end of the anchor cable (6) passes out from the grouting hole (5). The inner lining (1-1) is pre-drilled with a clearance hole corresponding to the position where the anchor cable (6) passes through. One end of the anchor cable (6) that passes through the grouting hole (5) is passed through the clearance hole and tightened.

5. The initial support structure for soft rock tunnels with large deformation according to claim 4, characterized in that, The grouting holes (5) are inclined at an angle of 30° to 60° toward the interior of the surrounding rock.

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