CN212296444U - Let pressure stock suitable for soft rock large deformation underground space - Google Patents
Let pressure stock suitable for soft rock large deformation underground space Download PDFInfo
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- CN212296444U CN212296444U CN202021003720.0U CN202021003720U CN212296444U CN 212296444 U CN212296444 U CN 212296444U CN 202021003720 U CN202021003720 U CN 202021003720U CN 212296444 U CN212296444 U CN 212296444U
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- yielding
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Abstract
The utility model discloses a let and press stock suitable for soft rock is warp underground space greatly, including the stock body and set up the resin anchoring agent at the stock body front end to and let and press attenuator, W type steel band, backing plate, spherical nut, hexagon nut and stock preloader that sets gradually at the stock body end. Compared with the prior art, the utility model has the positive effects that: the resin anchoring agent can provide enough anchoring force, so that primary support is more timely, and the possibility of large deformation of surrounding rocks is reduced; the pressure yielding structure of the anchor rod is matched with the W-shaped steel belt, so that the supporting effect of the anchor rod on weak surrounding rock is improved, and the condition of large deformation of the surrounding rock is reduced.
Description
Technical Field
The utility model relates to a let and press stock suitable for soft rock underground space that warp greatly.
Background
With the rapid development of railways, highway tunnel engineering and underground engineering in China, more and more tunnels are built in extra mountains, the absolute burial depth of the tunnels is larger and larger, and the tunnels need to pass through weak surrounding rock areas. The weak surrounding rock has the characteristics of high stress, complex geological structure, complex constitutive relation, expansibility and the like, so that the supporting effect of the existing supporting technology on the weak surrounding rock is poor. The prior supporting technology has the following three problems:
firstly, because surrounding rock is relatively broken or soft, a common mechanical anchoring head cannot provide enough anchoring force.
The anchor rod is not flexible enough, can only play a rigid support to soft rock, does not have a yielding function to cause too large support pressure, and is broken and damaged to lose the support effect.
The bearing plate is small in area, few surrounding rocks can be supported, the surrounding rocks which are not supported are prone to deformation and collapse under the action of stress, and the bearing plate can be phagocytized by the surrounding rocks in the deformation process.
The anchor bolt support is a recessive support, and due to the fact that a force measuring device is not installed, the change of support force in the anchor bolt support process cannot be monitored, the data cannot be analyzed and compared, and the effect of the anchor bolt support cannot be known.
Fifthly, the steel arch frame directly contacts with the surrounding rock, no yielding space is left between the rigid support and the deformed surrounding rock, when the surrounding rock deforms in the early stage, the stress of the surrounding rock is released without deformation, the steel arch frame can be directly damaged by the large stress of the surrounding rock, the cost and time for treatment such as arch dismantling and arch changing are greatly increased, and equipment damage and casualties can be seriously caused.
These problems directly affect the quality of the tunnel support, and further affect the overall quality, progress and construction cost of the project.
Disclosure of Invention
In order to overcome the above shortcoming of prior art, the utility model provides a let and press stock suitable for soft rock underground space that warp greatly.
The utility model provides a technical scheme that its technical problem adopted is: the yielding anchor rod suitable for the soft rock large-deformation underground space comprises an anchor rod body, a resin anchoring agent arranged at the front end of the anchor rod body, and a yielding damper, a W-shaped steel belt, a base plate, a spherical nut, a hexagonal nut and an anchor rod pretensioner which are sequentially arranged at the tail end of the anchor rod body.
Compared with the prior art, the utility model has the positive effects that:
the resin anchoring agent can provide enough anchoring force, so that primary support is more timely, and the possibility of large deformation of surrounding rock is reduced;
the yielding structure of the anchor rod is matched with the W-shaped steel belt, so that the supporting effect of the anchor rod on weak surrounding rocks is improved, and the situation of large deformation of the surrounding rocks is reduced;
the force sensor is used, so that the effect of anchor bolt support can be mastered in time, and the accumulated experience and the data support can be provided for future design of a support scheme;
the steel arch frame is arranged at a certain distance from the surrounding rock, a surrounding rock deformation space is reserved, the situation that the surrounding rock deforms and damages the steel arch frame is reduced, and the treatment cost of arch dismantling, arch changing and the like is saved.
Drawings
The invention will now be described, by way of example, with reference to the accompanying drawings, in which:
fig. 1 is a supporting schematic diagram of a yielding anchor rod;
FIG. 2 is a diagram showing a relation between a support characteristic curve and a surrounding rock characteristic curve;
FIG. 3 is a schematic structural view of a yielding bolt;
fig. 4 is a schematic structural view of an anchoring agent stent, in which: (1) side view, (2) perspective view;
fig. 5 is a schematic structural view of the centering cap, wherein: (1) a top view, (2) a front view, and (3) a bottom view;
FIG. 6 is a schematic view of the installation of the anchor rod body and centering cap;
fig. 7 is a schematic structural view of a W-shaped steel strip, in which: (1) top view, (2) side view;
FIG. 8 is a schematic view of tunnel lining stress;
fig. 9 is a schematic view of the overall arrangement of the anchor rods;
fig. 10 is a schematic view of arrangement of anchor rods in the longitudinal direction of the tunnel;
FIG. 11 is a schematic diagram of the construction of an annular force-measuring device, wherein: (1) a front view, (2) a left view, (3) a right view;
FIG. 12 is a schematic view of the installation between the annular force-measuring device and the spacer and ball nut;
fig. 13 is an installation schematic diagram of the centering cap, the resin anchoring agent, the anchoring agent bracket and the anchor rod body.
Detailed Description
The utility model discloses the defect to exist among the prior art has designed a new scheme of strutting: aiming at the problem of insufficient mechanical anchoring force, the resin anchoring agent is selected to provide the required anchoring force; aiming at the insufficient flexibility of the common anchor rod, the anchor rod with the yielding function is selected; aiming at the problem of small supporting area of the base plate, the W-shaped steel belt is designed to increase the supporting area; aiming at the problem that the change of the supporting force in the anchor bolt supporting process cannot be monitored, an annular force measuring device is designed; aiming at the problem that the steel arch frame is easy to be damaged in the early deformation stage, a proper yielding stroke gap is reserved between the steel arch frame and surrounding rocks. The following detailed description of the embodiments is provided in conjunction with the drawings:
design of supporting scheme
And performing advanced geological forecast on the area penetrated by the tunnel through geophysical prospecting and drilling, and collecting geological data comprising data such as geological structure, hydrogeological survey, rock-soil body physical and mechanical properties, surrounding rock grade and the like. And (4) providing a preliminary supporting scheme according to the data, establishing a model for analysis and calculation, adjusting the preliminary supporting scheme according to the calculation result, and determining a final supporting scheme.
1. Anchor type design
And (4) adopting yielding anchor rod support for tunnel sections which are easy to deform greatly. The yielding bolt can provide 'weak rigidity-flexibility-strong rigidity' support, as shown in figure 1. Namely, weak rigidity support is provided when the surrounding rock just begins to deform, as shown in the OA section; when the surrounding rock continues to deform, the support force provided by the anchor rod is yielding constant resistance, and is flexible support, as shown in section AB; when the deformation of the surrounding rock reaches the designed yielding stroke, the stress of the surrounding rock is released to a certain extent, the supporting force of the anchor rod is rapidly increased due to the limiting structure and becomes a strong rigid support, and the deformation of the surrounding rock is not allowed, as shown in a BC section. At the moment, the deformation of the surrounding rock is just equal to the reserved gap between the arch centering and the anchor-shotcrete supporting layer, namely, the anchor-shotcrete supporting layer is in contact with the outer side of the steel arch centering, and the steel arch centering starts to support the surrounding rock.
The supporting form allows surrounding rock to deform, releases the ground stress and reduces the supporting pressure, and meanwhile due to the limiting design of the yielding damper, the surrounding rock is restrained from loosening and excessively deforming, and the purpose of keeping the tunnel stable is achieved. Which letThe principle of the calculation of the pressure constant resistance and the yielding stroke is shown in fig. 2. When the country rock reaches the equilibrium with supporting construction in different positions, its load that is used in supporting construction is the complete difference: great stiffness of the supporting structure, i.e. u0At the moment, the required supporting force is too large and cannot be achieved generally; but the rigidity is less or the yielding stroke is too large, so that the unreasonable rigidity is not reasonable, and the load acting on the supporting structure after the surrounding rock is loosened and collapsed can be increased rapidly, namely an IV supporting curve.
Therefore, the preferred support point should be to the left of point D, adjacent to point E at point D; according to an empirical formula, determining ulimitThen, u is determined againE，uENamely, the yielding stroke is obtained according to the formula
Calculating the corresponding supporting force PE. Wherein C, gamma,
Is a physical parameter of the formation; r is0Is the tunnel radius; hcIs buried deep in the tunnel.
PESubtracting the supporting force provided by the sprayed concrete to obtain the yielding pressure required by the anchor rods, and equally dividing the yielding pressure to each anchor rod to obtain the yielding pressure constant resistance of each anchor rod.
In order to achieve the required constant yielding pressure, the formula P is 2 pi fISICAnd designing structural parameters of the yielding damper. Wherein IcIs the geometric parameter of the cone, IsIs the elastic constant of the sleeve. Their calculation formula is as follows:
wherein α is the half cone angle of the cone; h is the height of the cone; a is the diameter of the small end of the cone; b is the diameter of the large end of the cone; e, mu are the modulus of elasticity and Poisson's ratio, respectively, of the cannula.
The structure of the yielding anchor rod is shown in fig. 3 and comprises: the anchor rod comprises a resin anchoring agent 1, an anchoring agent support 2, a centering cap 3, an anchor rod body 4, a connecting sleeve 5, a yielding damper 6, a W-shaped steel belt 7, a backing plate 8, an annular force measuring device 9, a spherical nut 10, a hexagon nut 11, an anchor rod pretensioner 12 and the like.
2. Design of anchoring scheme
Because surrounding rocks are broken or soft, the ordinary mechanical anchoring head cannot provide enough anchoring force, and therefore the resin anchoring agent is selected to provide the anchoring force.
Meanwhile, in order to conveniently and quickly feed the resin anchoring agent, an anchoring agent bracket 2 is designed, the structure of which is shown in figure 4, the anchoring agent bracket is arranged at the tail part of the resin anchoring agent, and the resin anchoring agent is connected end to end.
3. Design of anchor rod body
The disturbance surrounding rock range is large after the tunnel is excavated, and the loosening ring can reach (2-10) m under the normal supporting condition; in order to exert the suspension and arch reduction effects of the anchor rod, the anchor rod can provide larger supporting force only by deepening the anchor rod into a relatively stable surrounding rock area to the maximum extent. And selecting the reasonable length of the anchor rod body according to the measured loosening ring. And a grout outlet needs to be formed at one end of the anchor rod body 4, which is in contact with the resin anchoring agent, for grouting.
As the yielding anchor rod is adopted, the yielding damper 6 is arranged; meanwhile, the connecting sleeve 5 of the bolt body needs to be connected, so that the diameter of the anchor hole is larger than that of the anchor hole drilled by a common resin anchor bolt, the length of the anchor bolt body of the anchor bolt is increased, the deflection is large, the distance between the head of the anchor bolt body and the wall of the anchor hole is too close or directly contacted, the resin anchoring agent wrapping the anchor bolt body is uneven, and the anchoring effect is influenced. After the centering cap 3 is added, the maximum outer diameter of the centering cap is close to the size of the anchor hole, so that the centering cap can be well attached to the anchor hole, the anchor rod body is centered, the size of a gap between the anchor rod body and the wall of the anchor hole is kept consistent, the resin anchoring agent wrapping the anchor rod body is more uniform, and the anchoring effect is ensured.
The centering cap 3 is structured as shown in fig. 5: the head is solid and can seal the head of the anchor rod body, so that the resin anchoring agent is prevented from flowing back to enter an inner hole of the anchor rod body to cause waste and reduce the anchoring effect; the tail part is provided with a wave-shaped thread for being arranged on the rod body. The mounting of the bolt body 4 and the centring cap 3 is shown in figure 6.
4. Scheme design of bearing contact surface
Because the size of the backing plate of the yielding anchor rod is smaller, the area of the surrounding rock which can be supported is small, and the surrounding rock which is not supported is easy to deform and collapse under the action of deformation stress. The existing design is that the W-shaped steel belt 7 is matched with a base plate to be used together, so that the supporting area is increased, and the effect of fully absorbing surrounding rock release pressure is achieved. And a plurality of dispersed anchor rods can be connected together to form an integral bearing structure through W-shaped steel belts. The structure of the W-shaped steel belt is as shown in FIG. 7, the two ends of the W-shaped steel belt are provided with the lower concave parts, the distance between the two lower concave parts is equal to the length of the backing plate 8, the backing plate 8 is placed between the two lower concave parts, and the firm installation between the W-shaped steel belt and the backing plate is ensured while the supporting area of the backing plate is increased.
5. Anchor rod arrangement design
Under the action of surrounding rock stress, the tunnel top lining deforms towards the inside of the tunnel to form a disengagement area, the two side linings deform towards the direction of the surrounding rocks to cause the passive elastic resistance of the surrounding rocks to the lining, and a resistance area is formed, as shown in fig. 8, wherein: the lining resistance area, such as the ab section in the figure, is arranged at the ab section in order to prevent the lining from being damaged due to deformation. The arrangement of the anchor rods determines the arrangement and number of the anchor rods per ring and the spacing between the rings as shown in fig. 9 and 10. The rings are staggered, so that the supporting force of the anchor rod can be distributed more uniformly.
6. Anchor bolt supporting force monitoring design
In the central area and the edge area of the anchor rod arrangement section, a plurality of anchor rods are selected, and an annular dynamometer 9 is additionally arranged between a backing plate 8 and a spherical nut 10 of each anchor rod to monitor the change condition of the supporting force in the anchor rod supporting process. So as to compare the quality of the bolting effect through data analysis, and also accumulate experience and provide data support for future design of a bolting scheme. The ring-shaped force-measuring device 9 is constructed as shown in fig. 11, and its mounting with the back plate 8 and the ball nut 10 is shown in fig. 12.
Second, support process
The method comprises the steps of timely spraying concrete to an excavated surface after the tunnel is excavated, wherein the thickness of the concrete is 4-6 cm.
And secondly, drilling an anchor hole after the initial spraying, and cleaning floating dust and accumulated water in the hole by using high-pressure air after drilling.
Thirdly, the centering cap 3 is arranged at the head of the anchor rod body 4, the resin anchoring agent 1 is filled into the anchoring agent bracket 2, and then the resin anchoring agent is pushed towards the bottom of the anchor hole by the rod body, as shown in fig. 13. When the anchor rod body is submerged into the anchor hole, the connecting sleeve 5 is connected with another anchor rod body, and the pushing is continued until the resin anchoring agent reaches the bottom of the anchor hole.
The anchor rod is stirred by a drilling machine with an anchor rod stirrer.
And fifthly, detaching the anchor rod stirrer, stabilizing the rod body in time, waiting for the resin anchoring agent to be cured, and not enabling the rod body to shift or rock during curing.
Sixthly, laying a reinforcing mesh.
And the U-shaped steel belt, the backing plate, the yielding damper, the annular force measurer, the spherical nut and the anchor rod pretensioner are sequentially arranged.
And applying a pre-stress with the drill-bolt pretensioner.
The self-lifting is proportionally prepared with mortar and grouted from the hollow rod body by a grouting machine.
The concrete is sprayed for the second time, and the thickness is 16-18 cm.
The steel arch frame is installed, and the distance between the steel arch frame and the edge of the secondary sprayed concrete surrounding rock is kept to be 15-17 cm.
Third, the concrete implementation case:
1. anchor rod scheme design
The design has the advantages that the pressure-yielding constant resistance is 65kN, and the pressure-yielding stroke is 150 cm.
The loose circle is measured to be 7.5 meters, so the anchor rod body needs to be 9 meters, and two anchor rod bodies with the length of 4.5 meters are connected by a connecting sleeve. And a grout outlet is formed at the position, 1.8m away from the contact end of the anchor rod body and the resin anchoring agent, and is used for grouting, two phi 6 through holes are formed in the anchor rod body, and the distance between the phi 6 through holes and the resin anchoring agent is 20cm and the phi 6 through holes are perpendicular to each other.
The diameter of the resin anchoring agent selected for use is phi 28mm, and the length is 500 mm; the type K, the gel time (41-90) s, the waiting installation time (90-180) s, the compressive strength is more than or equal to 40Mpa, each anchor rod is matched with 4 bags of resin anchoring agent for use, the anchoring length is 1.2m, and the pulling resistance can reach 100 kN.
The W-shaped steel belt is 3mm in thickness and 320mm in width, and is provided with holes phi 50 at intervals of 160 cm.
Fifthly, arranging 10 anchor rods in each ring, and 5 anchor rods on one side, wherein the circumferential distance of each anchor rod is 120 cm; the rings were spaced longitudinally from each other by 80cm, i.e., S1 was 120cm and S2 was 160 cm.
2. Supporting process
The C20 concrete is sprayed to the excavated surface in time after the tunnel is excavated, and the thickness is 4-6 cm.
And secondly, drilling an anchor hole after the initial spraying, wherein the diameter of the anchor hole is 42mm, the depth of the anchor hole is 8.7m, and after drilling, cleaning up the hole, sinking and water accumulation by using high-pressure air.
Thirdly, the centering cap is arranged at the head of the anchor rod body, the resin anchoring agent is placed into the anchor hole after being filled into the anchoring agent support, then the resin anchoring agent is pushed towards the bottom of the anchor hole by the rod body, when the anchor rod body is submerged into the anchor hole, the connecting sleeve is connected with another anchor rod body, and the resin anchoring agent is continuously pushed until the resin anchoring agent reaches the bottom of the anchor hole.
The anchor rod is stirred by the drilling machine with the anchor rod stirrer, and the stirring time is 30-40 seconds.
And fifthly, detaching the anchor rod stirrer, stabilizing the rod body in time, waiting for the resin anchoring agent to be cured, wherein the waiting time is 90-180 seconds, and the rod body is not required to be shifted or shaken in the process.
Sixthly, laying a reinforcing mesh, wherein the specification of the reinforcing mesh is E8-HPB235 multiplied by HPB235-4200mm multiplied by 1000 mm.
And the U-shaped steel belt, the backing plate, the yielding damper, the annular force measurer, the spherical nut and the anchor rod pretensioner are sequentially arranged.
And applying a pre-stress with the drill-bolt pretensioner.
The self-supporting substance is prepared into quick-setting mortar, sand grains are selected from fine sand, and cement is selected from portland cement. The components by weight portion are as follows: 100-120 parts of Portland cement, 90-100 parts of fine sand, 35-45 parts of water, 8-12 parts of an early strength agent and 2-6 parts of a water reducing agent.
The grouting is carried out through the hollow anchor rod body. And grouting pressure is 2-3 Mpa.
C20 concrete is sprayed for the second time, and the thickness of the concrete is 16-18 cm.
And (4) installing a steel arch frame, and keeping a distance of 15-17 cm with the sprayed concrete for the second time.
Claims (7)
1. The utility model provides a let and press stock suitable for soft rock underground space that warp greatly which characterized in that: the anchor rod comprises an anchor rod body, a resin anchoring agent arranged at the front end of the anchor rod body, and a yielding damper, a W-shaped steel belt, a base plate, a spherical nut, a hexagonal nut and an anchor rod pretensioner which are sequentially arranged at the tail end of the anchor rod body.
2. The yielding anchor rod applicable to the soft rock large-deformation underground space according to claim 1, characterized in that: an anchoring agent bracket is arranged at the front end of the anchor rod body, and the resin anchoring agent is filled in the anchoring agent bracket.
3. The yielding anchor rod applicable to the soft rock large-deformation underground space according to claim 1, characterized in that: the contact end of the anchor rod body and the resin anchoring agent is provided with a grout outlet.
4. The yielding anchor rod applicable to the soft rock large-deformation underground space according to claim 1, characterized in that: the head of the anchor rod body is provided with a centering cap.
5. The yielding anchor rod suitable for the soft rock large-deformation underground space as claimed in claim 4, wherein: the head of the centering cap is solid, and the tail of the centering cap is provided with a wave-shaped thread.
6. The yielding anchor rod applicable to the soft rock large-deformation underground space according to claim 1, characterized in that: and lower concave parts are arranged at two ends of the W-shaped steel strip, the distance between the two lower concave parts is equal to the length of a backing plate, and the backing plate is placed between the two lower concave parts.
7. The yielding anchor rod applicable to the soft rock large-deformation underground space according to claim 1, characterized in that: and an annular force measuring device is arranged between the backing plate and the spherical nut.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202021003720.0U CN212296444U (en) | 2020-06-04 | 2020-06-04 | Let pressure stock suitable for soft rock large deformation underground space |
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| CN202021003720.0U CN212296444U (en) | 2020-06-04 | 2020-06-04 | Let pressure stock suitable for soft rock large deformation underground space |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111608709A (en) * | 2020-06-04 | 2020-09-01 | 中铁隆昌铁路器材有限公司 | Yielding anchor rod suitable for soft rock large-deformation underground space and supporting method |
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- 2020-06-04 CN CN202021003720.0U patent/CN212296444U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111608709A (en) * | 2020-06-04 | 2020-09-01 | 中铁隆昌铁路器材有限公司 | Yielding anchor rod suitable for soft rock large-deformation underground space and supporting method |
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