CN110318771B - Device for reinforcing rock clamping in small clear distance tunnel and method for determining pre-applied axial force of opposite-pulling anchor rod - Google Patents
Device for reinforcing rock clamping in small clear distance tunnel and method for determining pre-applied axial force of opposite-pulling anchor rod Download PDFInfo
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- CN110318771B CN110318771B CN201910693688.9A CN201910693688A CN110318771B CN 110318771 B CN110318771 B CN 110318771B CN 201910693688 A CN201910693688 A CN 201910693688A CN 110318771 B CN110318771 B CN 110318771B
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- 239000011435 rock Substances 0.000 title claims abstract description 142
- 238000000034 method Methods 0.000 title claims abstract description 22
- 230000003014 reinforcing effect Effects 0.000 title claims abstract description 21
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 27
- 239000010959 steel Substances 0.000 claims abstract description 27
- 238000009412 basement excavation Methods 0.000 claims description 4
- 238000012544 monitoring process Methods 0.000 claims description 4
- 238000009933 burial Methods 0.000 claims description 3
- 238000006243 chemical reaction Methods 0.000 claims description 3
- 238000005070 sampling Methods 0.000 claims description 3
- 239000000463 material Substances 0.000 abstract description 5
- 230000006378 damage Effects 0.000 description 7
- 238000010276 construction Methods 0.000 description 3
- 230000002787 reinforcement Effects 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 235000002779 Morchella esculenta Nutrition 0.000 description 1
- 240000002769 Morchella esculenta Species 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
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Classifications
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D20/00—Setting anchoring-bolts
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D21/00—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection
- E21D21/02—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection having means for indicating tension
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
- E21D9/14—Layout of tunnels or galleries; Constructional features of tunnels or galleries, not otherwise provided for, e.g. portals, day-light attenuation at tunnel openings
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- Environmental & Geological Engineering (AREA)
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Abstract
The invention discloses a small clear distance tunnel rock clamping and reinforcing device and a method for determining the pre-axial force of a pull anchor rod, which are characterized in that: comprises a plurality of opposite-pull anchor rods and two steel plates; the two steel plates are respectively arranged on the two side surfaces of the middle clamping rock and are tightly attached to the two side surfaces of the middle clamping rock; the opposite-pulling anchor rod passes through the middle clamping rock and the two steel plates, the two steel plates are fixed on the two side surfaces of the middle clamping rock through the anchor device at the two ends of the opposite-pulling anchor rod, and the opposite-pulling anchor rod is applied with a pre-axial force. The middle clamping rock is in a three-way stress state, so that instability of the middle clamping rock is avoided; the invention can also further combine the existing design parameters to judge whether the diameter, material parameters, arrangement spacing and the like of the adopted split anchor rod meet the safety requirements.
Description
Technical Field
The invention belongs to the technical field of tunnel support, and particularly relates to a rock clamping and reinforcing device in a small clear-distance tunnel and a method for determining pre-applied axial force of a pull anchor rod.
Background
The tunnels of the expressway and the primary highway are designed into independent double holes for separating up and down. The minimum clear distance of the separated independent double holes is based on the principle that the structures of the two holes are not adversely affected. Under the condition of condition permission, the separated tunnels which are respectively arranged on the upper and lower sides can be adopted, but under certain specific conditions, such as difficult route separation or complex off-hole topography conditions, tense land, large removal quantity or adoption of the separated double-hole tunnels which are arranged on the upper and lower sides, the clear distance is very difficult to execute, especially the bridge tunnels are connected, and in this case, the small clear distance tunnel is a reasonable scheme. However, the thickness of the middle clamp rock of the small clear distance tunnel is far smaller than that of a common double-hole tunnel (generally only 5-8 m), and the stress is more complex than that of a common separation tunnel. In order to ensure that the structural form is successfully applied to highway construction, certain engineering measures are required to be taken to ensure the stability of the middle clamp rock; for the adoption of a pull-to-pull anchor rod, how to determine a reasonable pre-applied axial force value is not clearly specified in the highway tunnel design rule and the railway tunnel design rule at present, and the existing journal literature is mainly based on engineering individual cases and experiences, so that a scientific theoretical basis is lacked; under the condition of excessive pre-applied axial force, the safety of the middle rock clamping cannot be met; if the pre-applied axial force is too large, local damage can occur, even damage to the pull anchor rod body itself and the like; or the diameter of the opposite-pulling anchor rod body is too small to meet the requirements and the like.
Disclosure of Invention
In order to solve the technical problems, the invention provides a device which has simple structure and convenient operation and can avoid instability of middle-clamp rock; the method can also be used for further combining the existing design parameters to judge whether the diameter, material parameters, arrangement spacing and the like of the adopted split anchor rod meet the safety requirements.
The technical scheme adopted by the invention is as follows: a small clear distance tunnel middle rock clamping and reinforcing device comprises a plurality of opposite-pulling anchor rods and two steel plates; the two steel plates are respectively arranged on the two side surfaces of the middle clamping rock and are tightly attached to the two side surfaces of the middle clamping rock; the opposite-pulling anchor rod passes through the middle clamping rock and the two steel plates, the two steel plates are fixed on the two side surfaces of the middle clamping rock through the anchor device at the two ends of the opposite-pulling anchor rod, and the opposite-pulling anchor rod is applied with a pre-axial force.
In the small clear distance tunnel middle-clamping rock reinforcing device, cushion blocks are arranged at two ends of the opposite-pulling anchor rod, and the cushion blocks are located between the anchor and the steel plate.
The method for determining the pre-axial force of the pull anchor rod of the clamp rock reinforcing device in the small clear-distance tunnel comprises the following steps:
(1) Determining the vertical pressure sigma exerted on the top of the medium-pressure rock Top Its value is determined from on-site monitoring, or from the following equation:
wherein: gamma is the weight of the medium-pressure rock; h is the burial depth of the small clear distance tunnel; b is the excavation span of a single left hole or right hole of the small clear-distance tunnel; λ is a coefficient, determined by the following formula:
wherein: b (B) z Is the width of the middle clamp rock; beta is the angle of rupture, determined by:
to calculate the friction angle, it is obtained from the surrounding rock grade; θ is the calculated friction angle +.>The relevant angles are obtained according to the surrounding rock grade;
(2) Determining vertical pressure sigma of a split bolt at a distance z from the top of a rock clamp z Vertical pressure sigma of opposite-pulling anchor rod z Determined by the following formula:
σ z ＝σ top +γz
Wherein: gamma is the medium-clamp rock weight; z is the distance between the opposite-pulling anchor rod and the top of the rock clamping part in the distance; sigma (sigma) Top Vertical pressure at the top of the middle clamp;
(3) Determination of uniaxial compressive Strength Sigma of Medium-Sandwich c The value is determined by conversion of an indoor test or a site point load test according to site sampling; or according to the following formula:
wherein: c is the middleThe cohesive force of the clamping rock;is the internal friction angle of the middle clamp rock;
(4) Determining the lateral pressure p required for critical failure at a distance z from the top of the jacket z The value of which is determined by the following formula:
(5) Determining the pre-axial force F of the pull-to-pull anchor rod at the distance z from the top of the rock clamp z The value of which is determined by the following formula:
F z ＝p z ·Sx·Sy；
wherein: sx and Sy are respectively the horizontal spacing and the vertical spacing of the opposite-pull anchor rod arrangement.
In the method for determining the pre-axial force of the pull anchor rod of the rock clamping and reinforcing device in the small clear-distance tunnel, the friction angle in the step (1)The value method is as follows: when the surrounding rock is level I, the surrounding rock is level I>When the surrounding rock is level II, the surrounding rock is level II>The value range is 70-78 degrees; when the surrounding rock is III level, the surrounding rock is +.>The value range is 60-70 degrees; when the surrounding rock grade is IV, the surrounding rock grade is +.>The value range is 50-60 degrees; when the surrounding rock grade is V grade, the surrounding rock is +.>The value range is 40-50 degrees; when the surrounding rock grade is VI, the surrounding rock is +.>The value range is 30-40 degrees.
In the method for determining the pre-axial force of the pull anchor rod of the rock clamping and reinforcing device in the small clear-distance tunnel, the step (1) and the calculation of the friction angleThe related angle theta value method is as follows: when the surrounding rock is grade I, grade II or grade III>When the surrounding rock grade is IV, the surrounding rock grade is +.>When the surrounding rock grade is V grade, the surrounding rock is +.>When the surrounding rock grade is VI, the surrounding rock is +.>
In the method for determining the pre-axial force of the split anchor rod of the small clear-distance tunnel clamp rock reinforcing device, in order to avoid the phenomenon of passive damage of the middle clamp rock caused by overlarge pre-axial force of the split anchor rod, the pre-axial force value of the split anchor rod in the step (5) also meets the following conditions:
in the method for determining the pre-axial force of the split anchor rod of the rock clamping and reinforcing device in the small clear-distance tunnel, in order to avoid the phenomenon that the split anchor rod is damaged due to overlarge pre-axial force of the split anchor rod, the pre-axial force value of the split anchor rod in the step (5) also meets the following conditions:
wherein: d is the diameter of the opposite-pulling anchor rod; f (f) t The tensile strength of the opposite-pulling anchor rod; pi is the circumference ratio.
Compared with the prior art, the invention has the beneficial effects that:
1) According to the small clear distance tunnel middle-clamping rock reinforcing device, the pre-axial force is applied to the opposite-pulling anchor rod, so that the steel plate can uniformly distribute the pre-axial force provided by the opposite-pulling anchor rod on the middle-clamping rock while the steel plate is fixed, and the middle-clamping rock is in a three-way stress state, so that the middle-clamping rock is prevented from being unstable; the small clear distance tunnel middle-clamping rock reinforcing device can effectively prevent the middle-clamping rock from being locally damaged due to the concentration of the pre-stressing force of the pull anchor rod; the device also has the advantages of simple structure, convenient operation and low cost.
2) According to the method for determining the pre-axial force of the split anchor rod of the small clear-distance tunnel clamp rock reinforcing device, the pre-axial force of the split anchor rod is obtained through theoretical calculation, the influence of design experience of a designer is small, so that the obtained design parameters can meet the construction requirements of field engineering, the construction safety of the tunnel can be ensured, a scheme is provided for the reinforcement of the split anchor rod in the small clear-distance tunnel, the local damage of the split anchor rod caused by the concentration of the pre-axial force of the split anchor rod can be effectively prevented, and the possibility that the split anchor rod is in a unidirectional stress state and is easy to be unstable is also reduced; the method can further combine the existing design parameters to judge whether the diameter, the material parameters, the arrangement spacing and the like of the adopted tie-down anchors meet the safety requirements.
Drawings
Fig. 1 is a perspective view of a device for reinforcing a rock clamping in a small clear-distance tunnel according to the present invention.
Fig. 2 is a front view of a clip reinforcement device in a small clear-distance tunnel of the present invention.
Fig. 3 is a view in the direction a of fig. 2.
Fig. 4 is a schematic representation of the medium-clamp rock failure of the present invention.
Fig. 5 is a range diagram of the pre-applied axial force of the tie bolt of the present invention at different distances from the middle clamp.
In the figure: 1 is middle clamp rock; 2 is a steel plate; 3 is a pull-up anchor rod; 4 is a cushion block; 5 is a small clear distance tunnel left hole; 6 is a small clear distance tunnel right hole; f1, F2 and … Fn-1 and Fn are the pre-axial force of the pull anchor rod; sx and Sy are the horizontal spacing and the vertical spacing of the opposite-pull anchor rod arrangement; z is the distance of the top of the middle clamp rock; sigma (sigma) Top Vertical pressure at the top of the middle clamp; sigma (sigma) z Is the vertical pressure z distance from the top of the middle clamp; p is p z Is the horizontal average pressure z distance from the top of the middle clamp; p is p zmin Is the minimum horizontal average pressure z distance from the top of the middle clamp; p is p zmax Is the maximum horizontal average pressure z distance from the top of the middle clamp; b is the excavation span of a single left hole or right hole of the small clear-distance tunnel; b (B) z Is the width of the middle clamp rock; c is the cohesive force of the middle clamp rock;is the internal friction angle of the middle clamp rock; 7 breaking lines (Morle circle); 8 is a medium-clamp rock active damage critical safety line (Morr circle); 9 is a safety line (Morel circle); and 10 is a medium-clamp rock passive destruction critical safety line (Morr circle).
Detailed Description
The invention is further described below with reference to the accompanying drawings.
As shown in fig. 1 to 3, the small clear distance tunnel rock clamping and reinforcing device comprises two steel plates 2, a plurality of opposite-pulling anchor rods 3 and a plurality of cushion blocks 4. The two steel plates 2 are respectively arranged on the two side surfaces of the middle clamping rock 1, and the two steel plates 2 are tightly attached to the two side surfaces of the middle clamping rock 1. The opposite-pull anchor rod 3 passes through the middle clamping rock 1 and the two steel plates 2, and the two steel plates 2 are fixed on the two side surfaces of the middle clamping rock 1 by the anchors at the two ends 3 of the opposite-pull anchor rod. Cushion blocks 4 are arranged at two ends of the opposite-pull anchor rod 3, and the cushion blocks 4 are positioned between the anchor and the steel plate 2.
The pre-axial force is applied to the opposite-pulling anchor rod 3, the opposite-pulling anchor rod 3 is made of a material with the strength not smaller than HRB400, and the diameter of the opposite-pulling anchor rod 3 is not smaller than 25mm. The steel plate 2 has a yield strength not less than Q235, and the thickness of the steel plate 2 is not less than 2cm. The cushion block 4 is made of a steel plate with the yield strength not smaller than Q235, and the thickness of the cushion block 4 is not smaller than 0.5cm.
The use process of the rock clamping and reinforcing device in the small clear distance tunnel is as follows: two steel plates 2 are respectively fixed on two sides of the middle clamp rock 1; a hole is drilled in the middle clamp rock 1 and a counter-pulling anchor rod 3 is arranged. Cushion blocks 4 are arranged at the two ends of the opposite-pull anchor rod 3; and then tensioning the pull anchor rod 3 to form a pre-added axial force, wherein the pre-added axial force is diffused by the stress of the cushion block 4 and the steel plate 3, so that uniform horizontal pressure is formed, the middle clamp rock 1 is in a three-way stress state, and the instability of the middle clamp rock 1 can be avoided.
The invention relates to a method for determining the pre-axial force of a pull anchor rod of a rock clamping and reinforcing device in a small clear-distance tunnel, which comprises the following steps:
(1) Determining the vertical pressure sigma exerted on the top of the medium-pressure rock Top The value of the pressure sensor can be determined according to on-site monitoring, such as monitoring by burying a pressure box; it can also be determined according to the following formula:
wherein: gamma is the medium-clamp rock weight; h is the burial depth of the small clear distance tunnel; b is the excavation span of a single left hole or right hole of the small clear-distance tunnel; λ is a coefficient determined by:
wherein: b (B) z Is the width of the middle clamp rock; beta is the angle of rupture, determined by:
to calculate the friction angle, it can be obtained from the corresponding surrounding rock grades in table 1; θ is the calculated friction angle +.>The relevant angles can be obtained from the corresponding surrounding rock grades in table 2.
TABLE 1 different surrounding rock gradesValue of
Table 2 theta values for different surrounding rock grades
(2) Determining vertical pressure sigma at distance z of top of rock clamp in distance of opposite-pulling anchor rod z The value of which is determined by the following formula:
σ z ＝σ top +γz
Wherein, gamma is the weight of the medium-pressure rock; z is the distance between the opposite-pulling anchor rod and the top of the rock clamping part in the distance; sigma (sigma) z Vertical pressure at the opposite-pulling anchor rod; sigma (sigma) Top Is the vertical pressure at the top of the middle clamp.
(3) Determination of uniaxial compressive Strength Sigma of Medium-Sandwich c The value of the load test can be determined by conversion of an indoor test or a site point load test according to site sampling; if conditioned, it can be determined according to the following equation:
wherein: c is the cohesive force of the middle clamp rock;is the internal friction angle of the middle clamp rock.
(4) Determining the lateral pressure p required for critical failure at a distance z from the top of the jacket z The value of which is determined by the following formula:
(5) Determining the pre-axial force F of the pull-to-pull anchor rod at the distance z from the top of the rock clamp z The value of which is determined by the following formula:
F z ＝p z ·Sx·Sy
wherein: sx and Sy are the horizontal spacing and the vertical spacing of the opposite-pull anchor rod arrangement.
In order to avoid the phenomenon that the middle clamping rock is damaged passively due to overlarge pre-applied axial force of the pull anchor rod, the pre-applied axial force value of the pull anchor rod in the step (five) also meets the following conditions:
in order to avoid the phenomenon that the pull anchor rod is damaged due to overlarge pre-applied axial force, the pre-applied axial force value of the pull anchor rod in the step (five) also meets the following conditions:
wherein D is the diameter of the opposite-pulling anchor rod; f (f) t The tensile strength of the opposite-pulling anchor rod; pi is the circumference ratio.
Examples
The left hole span and the right hole span B=14m of a certain small clear distance tunnel, the buried depth H of the tunnel is 40m, and the width B of the medium clamp rock z Is 3m, the surrounding rock is V grade, and the gravity is 20kN/m 3 The cohesion c is 80kPa, the internal friction angle25 DEG, calculating the friction angle->According to table 1, 45 ° and θ according to table 2, 23 ° were taken, HRB400 material was used for the tie bolt, direct D was 32mm, the tensile strength was 400MPa, and the spacing was sx=sy=1m.
Then, the vertical pressure sigma of the top of the medium-pressure rock is obtained by the step (1) Top ＝758kPa
Obtaining vertical pressure sigma at the position where the distance of the top of the rock clamp in the distance of the opposite-pulling anchor rod is z=3m from the step (2) z ＝818kPa；
Determining the uniaxial compressive strength sigma of the medium-pressure rock from the step (3) c ＝251kPa；
From step (4) the lateral pressure p required for critical failure at a distance z from the top of the rock clamp is determined z ＝230kPa；
Determining the lowest pre-applied axial force F of the opposite-pulling anchor rod at the distance z from the top of the rock clamping in the step (5) z ＝230kN；
In order to avoid the phenomenon that the middle clamping rock is damaged passively due to overlarge axial force of the opposite-pull anchor rod, the axial force value of the opposite-pull anchor rod should be smaller than that of the opposite-pull anchor rod: 2.2672e+03kn;
in order to avoid the phenomenon that the pull anchor rod is damaged due to overlarge pre-applied axial force of the pull anchor rod, the pre-applied axial force value of the pull anchor rod is smaller than that of the pull anchor rod: 321kN.
Further, by changing the heights z, the minimum pre-applied axial force values of the opposite-pulling anchor rods at different heights of the middle-clamping rock can be obtained, and as can be seen from the table 3 and the figure 5, the pre-applied axial force value of the passive damage of the surrounding rock is far greater than the self-damage value of the opposite-pulling anchor rods, so that the pre-applied axial force value of the opposite-pulling anchor rods is controlled between the minimum value and the self-damage value of the opposite-pulling anchor rods; and as the distance of the roof of the rock is greater, the pre-applied axial force required is greater.
In this embodiment, if the diameter of the pull-up anchor is 22mm, the axial force value at which the pull-up anchor breaks itself is 152kN, which is not satisfactory, so if 22mm is used, it is not reasonable. So that the relevant design parameters can be checked whether the safety requirements are met.
TABLE 3 Pre-applied axial force values at different heights
Claims (3)
1. A method for determining the pre-axial force of a split anchor rod of a clamping and reinforcing device in a small-clear-distance tunnel comprises a plurality of split anchor rods and two steel plates; the two steel plates are respectively arranged on the two side surfaces of the middle clamping rock and are tightly attached to the two side surfaces of the middle clamping rock; the opposite-pulling anchor rod passes through the middle clamping rock and the two steel plates, the two steel plates are fixed on the two side surfaces of the middle clamping rock through an anchor device at the two ends of the opposite-pulling anchor rod, and a pre-axial force is applied to the opposite-pulling anchor rod;
the method comprises the following steps:
(1) Determining the vertical pressure sigma exerted on the top of the medium-pressure rock Top Its value is determined from on-site monitoring, or from the following equation:
wherein: gamma is the weight of the medium-pressure rock; h is the burial depth of the small clear distance tunnel; b is the excavation span of a single left hole or right hole of the small clear-distance tunnel; λ is a coefficient, determined by the following formula:
wherein: b (B) z Is the width of the middle clamp rock; beta is the angle of rupture, determined by:
to calculate the friction angle, according to the surrounding rockObtaining a grade; θ is the calculated friction angle +.>The relevant angles are obtained according to the surrounding rock grade;
friction angleThe value method is as follows: when the surrounding rock is level I, the surrounding rock is level I>When the surrounding rock is grade ii,the value range is 70-78 degrees; when the surrounding rock is III level, the surrounding rock is +.>The value range is 60-70 degrees; when the surrounding rock grade is IV, the surrounding rock grade is +.>The value range is 50-60 degrees; when the surrounding rock grade is V grade, the surrounding rock is +.>The value range is 40-50 degrees; when the surrounding rock grade is VI, the surrounding rock is +.>The value range is 30-40 degrees;
and calculating the friction angleThe related angle theta value method is as follows: when the surrounding rock is grade I, grade II or grade III,when the surrounding rock grade is IV, the surrounding rock grade is +.>When the surrounding rock is rated V,when the surrounding rock grade is VI, the surrounding rock is +.>
(2) Determining vertical pressure sigma of a split bolt at a distance z from the top of a rock clamp z Vertical pressure sigma of opposite-pulling anchor rod z Determined by the following formula:
σ z ＝σ top +γz
Wherein: gamma is the medium-clamp rock weight; z is the distance between the opposite-pulling anchor rod and the top of the rock clamping part in the distance; sigma (sigma) Top Vertical pressure at the top of the middle clamp;
(3) Determination of uniaxial compressive Strength Sigma of Medium-Sandwich c The value is determined by conversion of an indoor test or a site point load test according to site sampling; or according to the following formula:
wherein: c is the cohesive force of the middle clamp rock;is the internal friction angle of the middle clamp rock;
(4) Determining the lateral pressure p required for critical failure at a distance z from the top of the jacket z The value of which is determined by the following formula:
(5) Determining the pre-axial force F of the pull-to-pull anchor rod at the distance z from the top of the rock clamp z The value of which is determined by the following formula:
F z ＝p z ·Sx·Sy；
wherein: sx and Sy are respectively the horizontal spacing and the vertical spacing of the opposite-pull anchor rod arrangement.
2. The method for determining the pre-axial force of the pull anchor rod of the small clear-distance tunnel rock clamping reinforcing device according to claim 1, in order to avoid the phenomenon that the middle rock clamping is damaged passively due to the excessive pre-axial force of the pull anchor rod, the pre-axial force value of the pull anchor rod in the step (5) further satisfies:
3. the method for determining the pre-axial force of the pull anchor rod of the rock clamping and reinforcing device in the small clear-distance tunnel according to claim 1, in order to avoid the phenomenon that the pull anchor rod is damaged due to the excessive pre-axial force of the pull anchor rod, the pre-axial force value of the pull anchor rod in the step (5) further satisfies:
wherein: d is the diameter of the opposite-pulling anchor rod; f (f) t The tensile strength of the opposite-pulling anchor rod; pi is the circumference ratio.
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| CN112727512B (en) * | 2020-12-31 | 2022-09-16 | 同济大学 | Advanced detection, shock insulation and advanced transverse counter-pulling anchor rod system of ultra-small clear distance tunnel |
| CN113047865A (en) * | 2021-03-31 | 2021-06-29 | 中建二局第三建筑工程有限公司 | Clamping and reinforcing bent frame for middle rock pillar of large-section small-clear-distance tunnel and construction method of clamping and reinforcing bent frame |
| CN113266371A (en) * | 2021-06-15 | 2021-08-17 | 中交二公局萌兴工程有限公司 | Rock clamping fixing structure in weak surrounding rock small-clear-distance tunnel and construction method thereof |
| CN113569316B (en) * | 2021-07-29 | 2023-11-10 | 湖南科技大学 | Method for determining surrounding rock pressure of shallow buried unequal-span tunnel of soil stratum |
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| CN106050243A (en) * | 2016-07-28 | 2016-10-26 | 中冶建工集团有限公司 | Super-shallow-buried small-spacing large-section multi-tunnel concurrent construction method |
| CN108979676A (en) * | 2018-09-13 | 2018-12-11 | 中国建筑土木建设有限公司 | A kind of small interval overlapping tunnel folder rock ruggedized construction and its construction method |
| CN210264725U (en) * | 2019-07-30 | 2020-04-07 | 湖南科技大学 | Clamping rock combination reinforcing apparatus in little clear distance tunnel |
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