Tunnel structure applicable to large-deformation surrounding rock and tunnel surrounding rock large-deformation control method

Abstract

The present invention relates to a tunnel structure applicable to large-deformation surrounding rock and a method for controlling large deformation of tunnel surrounding rock, belonging to the field of tunnel engineering, and aims to reduce the influence of surrounding rock deformation on the tunnel structure. Radially, it includes the primary support on the outer layer and the secondary lining on the inner layer; longitudinally along the tunnel, a plurality of groups of deformation release holes are arranged on the outer periphery of the tunnel; each group has N deformation release holes, and the N deformation release holes in each group are arranged circumferentially around the tunnel; each deformation release hole is drilled from the primary support into the tunnel surrounding rock along the radial direction of the tunnel. For the tunnel structure applicable to large-deformation surrounding rock, by setting the deformation release holes, a deformation space is reserved for the tunnel surrounding rock, and part of the surrounding rock pressure is released, thereby reducing the pressure borne by the primary support and reducing the deformation of the primary support. For the method for controlling large deformation of tunnel surrounding rock, by continuously monitoring relevant data such as deformation and providing feedback for guiding construction, the deformation release holes are dynamically adjusted to be adapted to the surrounding rock deformation, so as to achieve the purpose of reasonably and effectively releasing the surrounding rock deformation pressure.

Description

Technical Field

[0001] The present invention belongs to the field of tunnel engineering, and specifically relates to a tunnel structure applicable to large-deformation surrounding rock and a method for controlling large deformation of tunnel surrounding rock. Background Art

[0002] With the rapid development of China's transportation industry, there are more and more projects of constructing long tunnels in areas with harsh geological environments, high ground stresses, and soft surrounding rocks. However, when constructing tunnels in such areas, the problem of large deformation of the surrounding rock is faced, which brings great potential safety hazards to the project construction.

[0003] For tunnels in large-deformation surrounding rock, currently, the method of increasing the support stiffness is often used to control the large deformation of the tunnel surrounding rock. For example, increasing the stiffness of the steel arch, increasing the thickness of the shotcrete, increasing the embedded length of the bolts, increasing the thickness and strength of the secondary lining, etc. to enhance the resistance to large deformation of the surrounding rock. However, in this method, due to the large deformation of the surrounding rock acting on the primary support during the construction stage, the primary support is extremely prone to large deformation. By increasing the stiffness and strength of the structure, not only the cost is increased, but also the excessive deformation of the surrounding rock will still cause problems such as deformation, intrusion, and collapse of the tunnel structure; during the later operation process, it will even cause diseases such as cracking of the secondary lining, and the treatment difficulty is extremely high. Summary of the Invention

[0004] The purpose of the present invention is to solve the problem of tunnel deformation caused by large deformation of the tunnel surrounding rock, and provide a tunnel structure applicable to large-deformation surrounding rock and a method for controlling large deformation of the tunnel surrounding rock, so as to reduce the influence of the surrounding rock deformation on the tunnel structure and effectively reduce the pressure of the surrounding rock deformation on the tunnel.

[0005] The technical solution adopted by the present invention is: a tunnel structure applicable to large-deformation surrounding rock, which includes a primary support on the outer layer and a secondary lining on the inner layer along its radial direction; along the longitudinal direction of the tunnel, within a longitudinal monitoring section of the tunnel, several groups of deformation release holes are arranged around the outer circumference of the tunnel; each group has N deformation release holes, and the N deformation release holes in each group are arranged around the circumferential direction of the tunnel; each of the deformation release holes is drilled from the primary support to the tunnel surrounding rock along the radial direction of the tunnel.

[0006] Furthermore, within a longitudinal monitoring section of the tunnel, the longitudinal spacing between adjacent groups of deformation release holes is equal and is M; the diameter of each deformation release hole is D; the depth of each deformation release hole is L; the total volume of the deformation release holes within a longitudinal monitoring section of the tunnel is V 孔 ;

[0007] V 孔 = 0.785 × D 2 × L × N ÷ M;

[0008] V 孔 = a(V - V0);

[0009] Where, V: natural deformation volume of surrounding rock in a tunnel longitudinal monitoring section;

[0010] V0: Convergence allowable deformation of surrounding rock in a tunnel longitudinal monitoring section;

[0011] A: Richness coefficient, 2≤a≤3.

[0012] Furthermore, each of the deformation release holes extends radially outward along the tunnel and is inclined forward along the longitudinal direction of the tunnel, and the inclination angle is 30-60°.

[0013] Furthermore, a drain pipe and a connecting pipe are provided; the drain pipe is inserted into the deformation release hole, and the open end of the drain pipe is located in the initial support of the tunnel; one end of the connecting pipe is connected to the open end of the drain pipe, and the other end is connected to the central drainage ditch of the tunnel; the outer diameter of the drain pipe is D1, D1≤D / 2.

[0014] Furthermore, the tunnel includes an inverted arch at the bottom and an arch at the top along its circumferential direction;

[0015] The connecting pipe comprises an arch connecting pipe connected to the drain pipe in the deformation release hole corresponding to the tunnel arch and a bottom connecting pipe connected to the drain pipe in the deformation release hole corresponding to the invert arch;

[0016] The arch connecting pipe includes a connecting section 1 and a connecting section 2; the other end of the connecting section 1 connected to the drain pipe extends to the tunnel arch foot along the inner wall of the arch initial support, and the other end of the connecting section 2 connected to the connecting section 1 passes through the secondary lining at the arch foot and extends to the central drainage ditch;

[0017] The other end of the bottom connecting pipe connected to the drain pipe extends to below the central drainage ditch along the inner wall of the initial support of the invert arch, and passes through the bottom wall of the central drainage ditch to be connected with the central drainage ditch.

[0018] The tunnel surrounding rock large deformation control method includes the following steps: first, dividing the tunnel into n tunnel longitudinal monitoring sections along the tunnel excavation direction, and determining whether each tunnel longitudinal monitoring section needs to be drilled with a deformation release hole:

[0019] 1) The deformation volume of the mth tunnel longitudinal monitoring section is V m ; Wherein, m = 1, 2...n; and the m-th tunnel longitudinal monitoring section has no deformation release hole drilled; then, V m Compare with the tunnel convergence allowable deformation V0; if V m >V0, deformation relief holes are drilled in the m+1th section; the total volume of the deformation relief holes drilled in the m+1th section is V 孔 , and V 孔 =a m+1 (V m -V0)=0.785×Dm+1 2 ×L m+1 ×N m+1 ÷M m+1 ;

[0020] 2) Monitor the tunnel deformation volume of the (m + 1)-th longitudinal monitoring section of the tunnel as V m+1 ; Compare V m+1 with the allowable deformation amount V0 of the tunnel convergence. If V m+1 > V0, then drill deformation release holes in the (m + 2)-th section; the total volume of the deformation release holes drilled in the (m + 2)-th section is V 孔 , and V 孔 = a m+2 (V m - V0) = 0.785 × D m+2 2 ×L m+2 ×N m+2 ÷M m+2 ; and a m+2 > a m+1 ;

[0021] Wherein, a is a rich coefficient, and 2 ≤ a ≤ 3.

[0022] Further, first drill deformation release holes from the inner side of the initial support of the tunnel radially into the surrounding rock; then, insert drain pipes into each deformation release hole and lay connecting pipes, one end of the connecting pipe is connected to the drain pipe, and the other end extends to the central drainage ditch; finally, construct the secondary lining.

[0023] Further, before drilling the deformation release holes, grout and reinforce the tunnel surrounding rock: drive grouting small pipes from the inner side of the initial support of the tunnel radially into the surrounding rock, and grout into the surrounding rock through the grouting small pipes, the grouting depth is H, and 4.5m ≤ H ≤ L / 2.

[0024] The beneficial effects of the present invention are: The tunnel structure applicable to large-deformation surrounding rock disclosed by the present invention reserves a deformation space for the tunnel surrounding rock through the setting of deformation release holes, releases part of the surrounding rock pressure, thereby reducing the pressure borne by the initial support and reducing the deformation of the initial support. Moreover, the deformation release holes of the present invention can be used to arrange drain pipes, which is conducive to discharging the groundwater deep in the rock layer and solving problems such as water swelling and water softening of the deformed body.

[0025] The tunnel surrounding rock large-deformation control method, by continuously monitoring relevant data such as deformation and feeding back to guide the construction, achieves dynamic adjustment of the deformation release holes to match the surrounding rock deformation, realizes reasonable and effective release of the surrounding rock deformation pressure, and thus reliably controls the deformation of the initial support. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the transverse sectional view of the present invention;

[0027] Figure 2 This is the partial schematic view of the deformation release hole of the present invention.

[0028] In the figure, there are deformation release holes 1, drain pipes 2, connecting pipes 3, arch connecting pipes 31, connecting section one 311, connecting section two 312, bottom connecting pipes 32, primary support 4, secondary lining 5, and central drainage ditch 6. Specific embodiments

[0029] The following further describes the present invention in conjunction with the attached drawings:

[0030] The tunnel structure applicable to large-deformation surrounding rock, as Figure 1 shown, includes the outer primary support 4 and the inner secondary lining 5 along its radial direction; along the longitudinal direction of the tunnel, within a longitudinal monitoring section of the tunnel, several groups of deformation release holes 1 are arranged around the outer periphery of the tunnel; each group has N deformation release holes 1, and the N deformation release holes 1 in each group are arranged around the circumferential direction of the tunnel; each of the deformation release holes 1 is drilled from the primary support 4 into the tunnel surrounding rock along the radial direction of the tunnel.

[0031] For the tunnel structure disclosed by the present invention, by drilling deformation release holes 1 into the tunnel surrounding rock, a deformation space is reserved for the tunnel surrounding rock, and part of the surrounding rock pressure is released, thereby reducing the pressure borne by the primary support 4 and reducing the deformation of the primary support 4, so as to avoid the secondary lining 5 occupying the space inside the tunnel.

[0032] In order to effectively release the surrounding rock pressure and control the tunnel deformation, preferably, within a longitudinal monitoring section of the tunnel, the longitudinal spacing between adjacent groups of deformation release holes 1 is equal and is M; the diameter of each deformation release hole 1 is D; the depth of each deformation release hole 1 is L; the total volume of the deformation release holes 1 within a longitudinal monitoring section of the tunnel is V 孔 ; the natural deformation volume of the surrounding rock within a longitudinal monitoring section of the tunnel is V; the allowable convergence deformation amount of the surrounding rock within a longitudinal monitoring section of the tunnel is V0:

[0033] V 孔 = 0.785 × D 2 × L × N ÷ M;

[0034] V 孔 = a(V - V0);

[0035] In the formula, for the convenience of on-site implementation, V0 is comprehensively determined by monitoring the deformation value of the primary support during construction on-site; A: is a rich coefficient, which is flexibly adjusted according to the deformation value of the primary support on-site, and usually 2 ≤ a ≤ 3.

[0036] The deformation release hole 1 can be drilled in the surrounding rock perpendicular to the tunnel excavation face. In order to release part of the surrounding rock pressure of the front face in advance and reduce the deformation of the front face, optimally, each of the deformation release holes 1 extends radially outward along the tunnel and is inclined forward along the longitudinal direction of the tunnel, and the inclination angle is 30-60°.

[0037] Since the surrounding rock deformation will swell when it meets water, thus aggravating the surrounding rock deformation, therefore, in the present invention, Figure 2 As shown, a drain pipe 2 and a connecting pipe 3 are also provided; the drain pipe 2 is inserted into the deformation release hole 1, and the open end of the drain pipe 2 is located in the initial support 4 of the tunnel; one end of the connecting pipe 3 is connected to the open end of the drain pipe 2, and the other end is connected to the central drainage ditch 6 of the tunnel.

[0038] The drainage pipe 2 is usually made of a perforated PVC pipe, and the PVC pipe is wrapped with non-woven fabric to prevent the rock from penetrating the drainage pipe 2 and blocking the pipeline drainage.

[0039] Preferably, the tunnel includes an inverted arch at the bottom and an arch at the top along its circumference;

[0040] The connecting pipe 3 includes an arch connecting pipe 31 connected to the drain pipe 2 in the deformation release hole 1 corresponding to the tunnel arch and a bottom connecting pipe 32 connected to the drain pipe 2 in the deformation release hole 1 corresponding to the invert arch;

[0041] The arch connecting pipe 3 includes a connecting section 1 311 and a connecting section 2 312; the other end of the connecting section 1 311 connected to the drain pipe 2 extends to the tunnel arch foot along the inner wall of the arch initial support 4, and the other end of the connecting section 2 312 connected to the connecting section 1 311 passes through the secondary lining 5 at the arch foot and extends to the central drainage ditch 6;

[0042] The other end of the bottom connecting pipe 32 connected to the drain pipe 2 extends along the inner wall of the inverted arch initial support 4 to the bottom of the central drainage ditch 6, and passes through the bottom wall of the central drainage ditch 6 to communicate with the central drainage ditch 6.

[0043] The connection pipe 3 does not occupy the secondary lining 5 or the space inside the tunnel. It is connected to the central drainage ditch (3) and can effectively drain the surrounding rock water to the central drainage ditch 6 of the tunnel, thus ensuring the reliability of drainage.

[0044] In order to prevent the drain pipe 2 from interfering with the deformation of the surrounding rock, or the deformation of the surrounding rock from squeezing the drain pipe 2, preferably, the outer diameter of the drain pipe 2 is d, d≤D / 2.

[0045] The method for controlling large deformation of tunnel surrounding rock, step 1, divides the tunnel into n tunnel longitudinal monitoring sections along the tunnel excavation direction, and determines whether each tunnel longitudinal monitoring section needs to be drilled with a deformation release hole 1:

[0046] 1) Monitor the tunnel deformation volume of the m-th longitudinal monitoring section of the tunnel as V m ; where m = 1, 2... n; and no deformation release holes 1 are drilled in the m-th longitudinal monitoring section of the tunnel; then, compare V m with the allowable deformation amount V0 of tunnel convergence; if V m > V0, drill deformation release holes 1 in the (m + 1)-th section; the total volume of the deformation release holes 1 drilled in the (m + 1)-th section is V, and V = a m+1 (V m - V0) = 0.785 × D m+1 2 × L m+1 × N m+1 ÷ M m+1 ;

[0047] 2) Monitor the tunnel deformation volume of the (m + 1)-th longitudinal monitoring section of the tunnel as V m+1 ; compare V m+1 with the allowable deformation amount V0 of tunnel convergence, if V m+1 > V0, then drill deformation release holes 1 in the (m + 2)-th section; the total volume of the deformation release holes 1 drilled in the (m + 2)-th section is V, and V = a m+2 (V m - V0) = 0.785 × D m+2 2 × L m+2 × N m+2 ÷ M m+2 ; and a m+2 > a m+1 ;

[0048] Among them, a is a rich coefficient, which is flexibly adjusted according to the on-site tunnel deformation volume, usually 2 ≤ a ≤ 3.

[0049] In the present invention, through monitoring of multiple longitudinal monitoring sections of the tunnel, continuously monitoring relevant data such as deformation, feeding back and guiding the construction, the reliability of controlling large deformation of surrounding rock is improved. By continuously monitoring relevant deformation data, it is beneficial to adjust the drilling depth and quantity of the deformation release holes 1 in subsequent construction, so as to achieve dynamic adjustment of the deformation release holes 1 to adapt to the surrounding rock deformation, realize reasonable and effective release of the surrounding rock deformation pressure, and thus achieve the purpose of controlling the deformation of the initial support 4.

[0050] In specific implementation, when m = 1, the tunnel deformation volume of the first longitudinal monitoring section of the tunnel is measured as V1. Since the deformation release holes 1 are not constructed in this section, V1 is also the natural deformation volume of the surrounding rock of the first longitudinal monitoring section of the tunnel. If V1 ≤ V0, then there is no need to drill deformation release holes 1 in the second longitudinal monitoring section of the tunnel. The tunnel deformation volume of the second longitudinal monitoring section of the tunnel measured is V2, which is also the natural deformation volume of the surrounding rock of the second longitudinal monitoring section of the tunnel. At this time, if V2 > V0, then the total volume V of the deformation release holes in the third longitudinal monitoring section of the tunnel 孔 = a3(V2 - V0), and then based on V 孔 = 0.785 × D3 2 × L3 × N3 ÷ M3, calculate the aperture, depth, quantity, etc. of the deformation release holes.

[0051] If V m > V0, then it is necessary to drill deformation release holes 1 in the second longitudinal monitoring section of the tunnel, and the total volume V of the deformation release holes in the second longitudinal monitoring section of the tunnel 孔 = a2(V1 - V0), and a2 can take 2, 3 or any value between 2 and 3. After drilling the deformation release holes in the second longitudinal monitoring section of the tunnel, the tunnel deformation volume V2 of the second longitudinal monitoring section measured is not the natural deformation volume of the surrounding rock, but the deformation amount after the pressure is released. At this time, if V2 ≤ V0, then for the third longitudinal monitoring section of the tunnel, the data of the deformation release holes 1 in the second longitudinal monitoring section can be used; if V2 > V0, then the total volume V of the deformation release holes in the third longitudinal monitoring section of the tunnel 孔 = a3(V1 - V0), where a3 > a2, that is, by adjusting the coefficient of abundance, the deformation release holes 1 are adjusted to meet the requirements of controlling deformation and can adapt to the construction needs.

[0052] Preferably, first, drill holes from the inner side of the initial support of the tunnel radially into the surrounding rock to form deformation release holes 1; then, insert drain pipes 2 into each deformation release hole 1, and lay connecting pipes 3, one end of the connecting pipe 3 is connected to the drain pipe 2, and the other end extends to the central drainage ditch 6; finally, construct the secondary lining 5.

[0053] In the present invention, the deformation release holes 1 are constructed after the initial support 4 of the tunnel is constructed, so that the initial support 4 can play a supporting role in time and reduce the safety problems caused by the drilling of the deformation release holes 1. Moreover, compared with the traditional tunnel construction, the entire construction project only adds step two and step three, and the construction of the drain pipe 2 in step three is synchronized with the tunnel drainage system, which has little impact on the construction period.

[0054] In order to further alleviate the deformation of surrounding rock, preferably, before drilling the deformation release holes 1, the surrounding rock of the tunnel is grouted and reinforced: grouting small pipes are driven into the surrounding rock radially from the inner side of the initial support of the tunnel, and grout is injected into the surrounding rock through the grouting small pipes. The grouting depth is H, and 4.5m ≤ H ≤ L / 2. By grouting, the surrounding rock is reinforced, and the grouted and reinforced part can play a pressure-bearing role and can further reduce the deformation of the surrounding rock.

Claims

1. A method for controlling large deformation of tunnel surrounding rock, characterized in that: A tunnel structure applicable to large-deformation surrounding rock. The tunnel structure includes an outer primary support (4) and an inner secondary lining (5) along its radial direction; longitudinally along the tunnel, within a longitudinal monitoring section of the tunnel, a plurality of groups of deformation release holes (1) are arranged around the outer periphery of the tunnel; each group of deformation release holes (1) has N holes, and the N deformation release holes (1) in each group are arranged circumferentially around the tunnel; each of the deformation release holes (1) is drilled from the primary support (4) into the tunnel surrounding rock along the radial direction of the tunnel; a drain pipe (2) and a connecting pipe (3) are also provided; the drain pipe (2) is inserted into the deformation release hole (1), and the open end of the drain pipe (2) is located within the primary support (4) of the tunnel; one end of the connecting pipe (3) is communicated with the open end of the drain pipe (2), and the other end is communicated with the central drainage ditch (6) of the tunnel; within a longitudinal monitoring section of the tunnel, the longitudinal spacing between adjacent groups of deformation release holes (1) is equal and is M; the diameter of each deformation release hole (1) is D; the depth of each deformation release hole (1) is L; the total volume of the deformation release holes (1) within a longitudinal monitoring section of the tunnel is V 孔 ; V 孔 = 0.785 × D 2 × L × N ÷ M; V 孔 = a(V - V0); Where, V: natural deformation volume of surrounding rock in a tunnel longitudinal monitoring section; V0: Convergence allowable deformation of surrounding rock in a tunnel longitudinal monitoring section; a: richness coefficient, 2≤a≤3; Step 1: Divide the tunnel into n tunnel longitudinal monitoring sections along the tunnel excavation direction, and determine whether each tunnel longitudinal monitoring section needs to be drilled with a deformation release hole (1): 1) Monitor the tunnel deformation volume of the m-th longitudinal monitoring section of the tunnel as V m ; where m = 1, 2... n; and no deformation release holes (1) are drilled in the m-th longitudinal monitoring section of the tunnel; then, compare V m with the allowable deformation amount V0 of the tunnel convergence; if V m > V0, drill deformation release holes (1) in the (m + 1)-th section; the total volume of the deformation release holes (1) drilled in the (m + 1)-th section is V 孔 , and V 孔 = a m+1 (V m - V0) = 0.785 × D m+1 2 × L m+1 × N m+1 ÷ M m+1 ; 2) Monitor the tunnel deformation volume of the (m + 1)-th longitudinal monitoring section of the tunnel as V m+1 ; Compare V m+1 with the allowable deformation amount V0 of the tunnel convergence. If V m+1 > V0, then drill deformation release holes (1) in the (m + 2)-th section; the total volume of the deformation release holes (1) drilled in the (m + 2)-th section is V 孔 , and V 孔 = a m+2 (V m - V0) = 0.785 × D m+2 2 × L m+2 × N m+2 ÷ M m+2 ; and a m+2 > a m+1 .

2. The method for controlling large deformation of tunnel surrounding rock according to claim 1, characterized in that: Each of the deformation release holes (1) extends radially outwards along the tunnel and is arranged tilted forwards along the longitudinal direction of the tunnel, with an inclination angle of 30-60°.

3. The method for controlling large deformation of tunnel surrounding rock according to claim 1, characterized in that: The outer diameter of the drain pipe (2) is D1, where D1≤D / 2.

4. The method for controlling large deformation of tunnel surrounding rock according to claim 3, characterized in that: The tunnel includes an inverted arch at the bottom and an arch at the top along its circumference; The connecting pipe (3) comprises an arch connecting pipe (31) connected to a drain pipe (2) in a deformation release hole (1) corresponding to the tunnel arch, and a bottom connecting pipe (32) connected to a drain pipe (2) in a deformation release hole (1) corresponding to the inverted arch; The arch connecting pipe (31) comprises a connecting section 1 (311) and a connecting section 2 (312); the other end of the connecting section 1 (311) connected to the drain pipe (2) extends to the tunnel arch foot along the inner wall of the initial support (4) of the arch, and the other end of the connecting section 2 (312) connected to the connecting section 1 (311) passes through the secondary lining (5) at the arch foot and extends to the central drainage ditch (6); The other end of the bottom connecting pipe (32) connected to the drain pipe (2) extends to the bottom of the central drainage ditch (6) along the inner wall of the initial support (4) at the inverted arch, and passes through the bottom wall of the central drainage ditch (6) to communicate with the central drainage ditch (6).

5. The tunnel surrounding rock large deformation control method according to claim 1, characterized in that: First, a deformation release hole (1) is drilled from the inner side of the initial support of the tunnel into the surrounding rock along the radial direction of the tunnel; then, a drainage pipe (2) is inserted into each deformation release hole (1), and a connecting pipe (3) is laid, one end of the connecting pipe (3) is connected to the drainage pipe (2), and the other end extends to the central drainage ditch (6); finally, a secondary lining (5) is constructed.

6. The method for controlling large deformation of tunnel surrounding rock according to claim 5, characterized in that: Before drilling the deformation release hole (1), the tunnel surrounding rock is reinforced by grouting: a small grouting pipe is driven into the surrounding rock along the radial direction of the tunnel from the inner side of the initial support of the tunnel, and grouting is injected into the surrounding rock through the small grouting pipe. The grouting depth is H, and 4.5m≤H≤L / 2.

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