Summary of the invention
In view of the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present invention is that providing a kind of soft rock tunnel
Side wall asymmetric method for protecting support, method and step is simple, design rationally and realizes that convenient, using effect is good, by being in
Tunnel sidewalls surrouding rock deformation situation under the sliding failure by shear state of drawing crack-is analyzed, and asymmetric using tunnel sidewalls
Formula supporting construction carries out effective support to tunnel sidewalls, can control effectively to the surrouding rock deformation of soft rock tunnel side wall.
In order to solve the above technical problems, the technical solution adopted by the present invention is that: a kind of soft rock tunnel side wall asymmetric branch
Maintaining method, it is characterised in that: divide multiple segments to carry out excavation and tunnel to soft rock tunnel from the front to the back along tunnel longitudinal extension
Road side wall supporting construction, the excavation and tunnel sidewalls construction method for supporting of multiple segments are all the same;The soft rock tunnel is
Deep tunnel, buried depth H >=2B of the soft rock tunnel, wherein B is the excavation width of soft rock tunnel, and the unit of H and B are m;It is right
When any segment carries out excavation and tunnel sidewalls supporting construction, comprising the following steps:
Step 1: country rock basic mechanical parameter determines: by boring sample to scene and carrying out laboratory test, to currently being applied
The country rock basic mechanical parameter of work segment is tested, and synchronizes record to test result;
Step 2: tunnel sidewalls asymmetric supporting construction determines: used tunnel sidewalls asymmetric supporting construction
The tunnel sidewalls support system excavated in molding Tunnel is laid in from the front to the back along tunnel extending direction including multiple, it is multiple
The structure of the tunnel sidewalls support system is all the same;Each tunnel sidewalls support system includes that left and right two is right respectively
The left and right side walls of the Tunnel carries out the side wall supporting unit of supporting, and two side wall supporting units are symmetrically arranged and two
Person is laid on same tunnel cross section;
Each side wall supporting unit is to carry out the non-right of supporting to the side wall caving zone on the Tunnel side wall
Title formula supporting construction, the top of the side wall caving zone and the side wall top flush of the Tunnel, the side wall caving zone
Cross section be right-angled trapezium and it include top drawing crack area and the lower part slip region immediately below top drawing crack area, institute
The cross section for stating top drawing crack area is rectangle, and the cross section of the lower part slip region is right angled triangle and upper part width and institute
State the of same size of top drawing crack area;Each side wall supporting unit include side wall deep support structure and be located at the side
Side wall shallow-layer supporting construction immediately below wall deep support structure;It is in horizontal layout that the side wall deep support structure, which includes one,
And the side wall anchor cable of supporting is carried out to top drawing crack area, the side wall shallow-layer supporting construction includes more from top to bottom to institute
State the side wall anchor pole that lower part slip region carries out supporting, more side wall anchor poles in it is parallel lay and its from the inside to the outside gradually to
Lower inclination;
The side wall design height of the TunnelWherein c is segment of currently being constructed
Tunnel sidewalls Rock Mass cohesive strength,By the internal friction angle of the tunnel sidewalls Rock Mass of current construction segment, q is
The overlying rock of current constructed segment acts on the well-distributed pressure on tunnel sidewalls country rock and q=γ0(h1+h2), γ is current
The volume-weighted average of the tunnel sidewalls Rock Mass of constructed segment, γ0By the average appearance of the overlying rock of current construction segment
Weight, γ and γ0Unit be N/m3, the unit of c and q are Pa;h1For the Tunnel the tunnel roof inbreak pitch of arch andSolid coefficient of the f by current construction segment overlying rock, h2It is described
The arch design height of Tunnel, h2+h3=h4, h4For the design excavation height of the Tunnel, h1、h2、h3And h4Unit it is equal
For m;
When being determined to the tunnel sidewalls asymmetric supporting construction, prop up used by the side wall supporting unit
Protection structure is determined, and process is as follows:
Step 201, the slide surface inclination angle of side wall caving zone, inside height, outside height and collapsing width determine: in conjunction with step
Identified country rock basic mechanical parameter in rapid one, and according to formulaCurrent constructed segment is calculated
The slide surface inclination alpha of side wall caving zone;In formula, ψ by the tunnel sidewalls Rock Mass of current construction segment dilative angle;It is described
The slide surface inclination alpha of side wall caving zone is the folder between the slide surface and horizontal plane of lower part slip region described in side wall caving zone
Angle;
Further according to formula With
Calculate separately the inside height h for obtaining the side wall caving zone of current constructed segment0, outside height z and collapsing width b, h0, z and
The unit of b is m, and 90 ° of α <;
The height in top drawing crack area is z and its width is b, and the height of the lower part slip region is h0-z;
Step 202, supporting construction determine: according to the slide surface inclination alpha of the side wall caving zone determined in step 201, inside
Height h0, outside height z and collapsing width b, to side wall deep support structure described in the side wall supporting unit and the side
Supporting construction used by wall shallow-layer supporting construction is determined respectively;
Step 3: tunnel excavation and the synchronous supporting construction of tunnel sidewalls: opening from the front to the back current constructed segment
It digs, according to the tunnel sidewalls asymmetric supporting construction identified in step 2 in digging process, from the front to the back to excavation
The molding Tunnel left and right side walls carries out supporting respectively;
Step 4: next segment is excavated and the synchronous supporting construction of tunnel sidewalls: repeating step 1 to step 3, to next section
Duan Jinhang is excavated and the synchronous supporting construction of tunnel sidewalls;
Step 5: step 4 is repeated several times, until the whole for completing soft rock tunnel is excavated and the synchronous supporting of tunnel sidewalls is applied
Work process.
Above-mentioned a kind of soft rock tunnel side wall asymmetric method for protecting support, it is characterized in that: the longitudinal length of multiple segments
It is 10m~50m.
Above-mentioned a kind of soft rock tunnel side wall asymmetric method for protecting support, it is characterized in that: carrying out country rock fundamental force in step 1
Before parameter determines, a segmentation is first chosen from current constructed segment, test section is used as to be excavated;In step 1 into
When row country rock basic mechanical parameter determines, bores sample from the test section and carry out laboratory test, and test result obtained is
The country rock basic mechanical parameter of current constructed segment after excavation.
Above-mentioned a kind of soft rock tunnel side wall asymmetric method for protecting support, it is characterized in that: the two neighboring institute in front and back in step 2
Stating the spacing between tunnel sidewalls support system is 0.8m~1.2m.
Above-mentioned a kind of soft rock tunnel side wall asymmetric method for protecting support, it is characterized in that: to the side wall deep layer in step 202
When supporting construction used by supporting construction is determined, it is determined according to the installation position of the opposite side outside height z joist anchor rope
And it is located at side wall anchor cable in top drawing crack area, is determined according to the length of the opposite side collapsing width b joist anchor rope and makes side
The front end of joist anchor rope is extend out on the outside of top drawing crack area;
When being determined to supporting construction used by the side wall shallow-layer supporting construction, according to slide surface inclination alpha opposite side
The tilt angle of joist anchor bar is determined, according to inside height h0With the laying of outside height z and the opposite side collapsing width b joist anchor bar
Position is determined and is laid in the more side wall anchor poles from top to bottom on the lower part slip region, according to collapsing width b
The length of opposite side joist anchor bar is determined and extend out to the front end of the every side wall anchor pole on the outside of the lower part slip region.
Above-mentioned a kind of soft rock tunnel side wall asymmetric method for protecting support, it is characterized in that: according to the opposite side collapsing width b joist anchor rope
Length when being determined, the length L of the side wall anchor cable1=l1+L1+l2, wherein l1=0.1m~15cm, l2=0.3m~
0.4m, L1 >=1.5b;
When being determined according to the length of the opposite side collapsing width b joist anchor bar, the length L of the side wall anchor pole2=l1+L2+
l2, wherein L2 >=b and L2 < L1.
Above-mentioned a kind of soft rock tunnel side wall asymmetric method for protecting support the, it is characterized in that: L1=3b~6b, described
L2=1.5b~3b.
Above-mentioned a kind of soft rock tunnel side wall asymmetric method for protecting support, it is characterized in that: according to slide surface inclination alpha opposite side joist anchor
When the tilt angle of bar is determined, 1=180 ° of-α-α of inclination angle alpha of side wall anchor pole0, α0It collapses for side wall anchor pole and side wall
Angle and 65 °≤α between the slide surface of lower part slip region described in area0≤ 75 °, α 1 is between side wall anchor pole and horizontal plane
Angle.
Above-mentioned a kind of soft rock tunnel side wall asymmetric method for protecting support, it is characterized in that: the branch of side wall shallow-layer described in step 2
The quantity of included side wall anchor pole is three in protection structure, and three side wall anchor poles are in uniformly distributed.
Above-mentioned a kind of soft rock tunnel side wall asymmetric method for protecting support, it is characterized in that: the position of side wall anchor cable described in step 2
In the middle part in top drawing crack area, the spacing between the side wall top of the side wall anchor cable and the Tunnel is
Compared with the prior art, the present invention has the following advantages:
1, construction method step is simple, realizes that convenient and input cost is low.
2, design is rationally and realization is convenient, passes through supporting used by rationally designing tunnel sidewalls asymmetric supporting construction
Structure effectively reinforces tunnel sidewalls, can effectively solve the sliding failure by shear problem of drawing crack-of tunnel sidewalls.
3, support structure design used by tunnel sidewalls asymmetric supporting construction is rationally and realization is convenient, each side wall
Supporting unit is all made of asymmetric supporting construction up and down, when determining supporting scheme, considers that the drawing crack-of tunnel sidewalls is sliding and cuts
Sliding is cut, and according to the slide surface inclination alpha of side wall caving zone, inside height h0, outside height z and collapsing width b be determined,
Tunnel sidewalls in the sliding shearing slip state of drawing crack-can effectively be reinforced, thus can effectively ensure tunnel sidewalls
The validity and stability of supporting reach the mesh of save the cost in this way under the premise of meeting stable supporting, reliable and safety
, have many advantages, such as that economical, investment construction cost is lower, safe and reliable, thus can be provided effectively for soft rock tunnel safe construction
It ensures.
4, using effect is good, carries out effective support, and energy to tunnel sidewalls using tunnel sidewalls asymmetric supporting construction
Effectively control tunnel sidewalls failure and deformation of surrounding rocks, effectively reinforces tunnel sidewalls.
In conclusion the method for the present invention step is simple, design rationally and realizes that convenient, using effect is good, by being in
Tunnel sidewalls surrouding rock deformation situation under the sliding failure by shear state of drawing crack-is analyzed, and asymmetric using tunnel sidewalls
Formula supporting construction carries out effective support to tunnel sidewalls, can control effectively to the surrouding rock deformation of soft rock tunnel side wall.
Below by drawings and examples, technical scheme of the present invention will be described in further detail.
Specific embodiment
A kind of soft rock tunnel side wall asymmetric method for protecting support as shown in Figure 1, along tunnel longitudinal extension by backward
Preceding point of multiple segments carry out excavation and tunnel sidewalls supporting construction, the excavation of multiple segments and tunnel side to soft rock tunnel 1
Wall construction method for supporting is all the same;The soft rock tunnel 1 be deep tunnel, buried depth H >=2B of the soft rock tunnel 1, wherein B be
The unit of the excavation width of soft rock tunnel 1, H and B are m;When carrying out excavation and tunnel sidewalls supporting construction for any segment,
The following steps are included:
Step 1: country rock basic mechanical parameter determines: by boring sample to scene and carrying out laboratory test, to currently being applied
The country rock basic mechanical parameter of work segment is tested, and synchronizes record to test result;
Step 2: tunnel sidewalls asymmetric supporting construction determines: used tunnel sidewalls asymmetric supporting construction
The tunnel sidewalls support system excavated in molding Tunnel is laid in from the front to the back along tunnel extending direction including multiple, it is multiple
The structure of the tunnel sidewalls support system is all the same;Each tunnel sidewalls support system includes that left and right two is right respectively
The left and right side walls of the Tunnel carries out the side wall supporting unit of supporting, and two side wall supporting units are symmetrically arranged and two
Person is laid on same tunnel cross section;
In conjunction with Fig. 2, each side wall supporting unit is to prop up the side wall caving zone 3 on the Tunnel side wall
The asymmetric supporting construction of shield, the top of the side wall caving zone 3 and the side wall top flush of the Tunnel, the side
The cross section of wall caving zone 3 be right-angled trapezium and it include top drawing crack area and the lower part immediately below top drawing crack area
Slip region, the cross section in top drawing crack area are rectangle, and the cross section of the lower part slip region is right angled triangle and thereon
Portion's width is of same size with top drawing crack area;Each side wall supporting unit include side wall deep support structure and
Side wall shallow-layer supporting construction immediately below the side wall deep support structure;The side wall deep support structure includes one
The side wall anchor cable 4 of supporting is carried out in horizontal layout and to top drawing crack area, the side wall shallow-layer supporting construction includes more
From top to bottom carry out the side wall anchor pole 5 of supporting to the lower part slip region, more side wall anchor poles 5 in it is parallel lay and its
It tilts gradually downward from the inside to the outside;
The side wall design height of the TunnelWherein c is segment of currently being constructed
Tunnel sidewalls Rock Mass cohesive strength,By the internal friction angle of the tunnel sidewalls Rock Mass of current construction segment, q is
The overlying rock of current constructed segment acts on the well-distributed pressure on tunnel sidewalls country rock 2 and q=γ0(h1+h2), γ is to work as
The volume-weighted average of the tunnel sidewalls Rock Mass of preceding constructed segment, γ0It is averaged by the overlying rock of current construction segment
Bulk density, γ and γ0Unit be N/m3, the unit of c and q are Pa;h1For the tunnel roof inbreak pitch of arch of the Tunnel
AndSolid coefficient of the f by current construction segment overlying rock, h2For institute
State the arch design height of Tunnel, h2+h3=h4, h4For the design excavation height of the Tunnel, h1、h2、h3And h4Unit
It is m;
When being determined to the tunnel sidewalls asymmetric supporting construction, prop up used by the side wall supporting unit
Protection structure is determined, and process is as follows:
Step 201, the slide surface inclination angle of side wall caving zone, inside height, outside height and collapsing width determine: in conjunction with step
Identified country rock basic mechanical parameter in rapid one, and according to formulaCurrent constructed segment is calculated
The slide surface inclination alpha of side wall caving zone 3;In formula, ψ by the tunnel sidewalls Rock Mass of current construction segment dilative angle;Institute
The slide surface inclination alpha for stating side wall caving zone 3 is between the slide surface and horizontal plane of lower part slip region described in side wall caving zone 3
Angle;
Further according to formula With
Calculate separately the inside height h for obtaining the side wall caving zone 3 of current constructed segment0, outside height z and collapsing width b, h0、z
Unit with b is m, and 90 ° of α <;
The height in top drawing crack area is z and its width is b, and the height of the lower part slip region is h0-z;
Step 202, supporting construction determine: according to the slide surface inclination alpha of the side wall caving zone 3 determined in step 201, inside
Height h0, outside height z and collapsing width b, to side wall deep support structure described in the side wall supporting unit and the side
Supporting construction used by wall shallow-layer supporting construction is determined respectively;
Step 3: tunnel excavation and the synchronous supporting construction of tunnel sidewalls: opening from the front to the back current constructed segment
It digs, according to the tunnel sidewalls asymmetric supporting construction identified in step 2 in digging process, from the front to the back to excavation
The molding Tunnel left and right side walls carries out supporting respectively;
Step 4: next segment is excavated and the synchronous supporting construction of tunnel sidewalls: repeating step 1 to step 3, to next section
Duan Jinhang is excavated and the synchronous supporting construction of tunnel sidewalls;
Step 5: step 4 is repeated several times, until the whole for completing soft rock tunnel 1 is excavated and the synchronous supporting of tunnel sidewalls is applied
Work process.
Wherein, a is tunnel half-breadth.
In the present embodiment, when being excavated in step 3 to current constructed segment, using full face tunneling method or step
Method is excavated.
Also, used full face tunneling method or benching tunnelling method are conventional tunnel excavation method.
In the present embodiment, when the Tunnel formed after excavating to current constructed segment carries out preliminary bracing, adopted
Tunnel structure is that the Bolt net and jet preliminary bracing structure of supporting, the Bolt net and jet are carried out to the Tunnel arch wall
Preliminary bracing structure is the preliminary bracing structure using bolt-mesh-spurting supporting method construction molding;
The Bolt net and jet preliminary bracing structure includes the supporting construction of tunnel sidewalls asymmetric described in step 2.Also,
The Bolt net and jet preliminary bracing structure further includes that one layer of steel mesh being mounted on the Tunnel arch wall and one layer are injected in institute
The concrete ejection layer on Tunnel arch wall is stated, the steel mesh is fixed in the concrete ejection layer.Wherein, the arch wall
Arch and left and right sides tunnel side wall including the Tunnel.
In the present embodiment, the concrete layer is steel fiber concrete layer and its thickness is 20cm~30cm.
Also, when constructing to the Bolt net and jet preliminary bracing structure, used construction method is conventional construction
Method.
In the present embodiment, the concrete layer is steel fiber concrete layer and its thickness is 20cm~30cm.
In the present embodiment, the longitudinal length of multiple segments is 10m~50m.
When practice of construction, according to specific needs, the longitudinal length of the segment is adjusted accordingly.
In the present embodiment, before progress country rock basic mechanical parameter determines in step 1, first from current constructed segment
A segmentation is chosen to be excavated as test section;When progress country rock basic mechanical parameter determines in step 1, from the test
Section, which is bored sample, carries out laboratory test, and test result obtained is by currently the country rock basic mechanical of construction segment is joined after excavation
Number.
In the present embodiment, the test section is located at current constructed segment rear end and the length is 1m.
When progress country rock basic mechanical parameter determines in step 1, bores sample from the test section and carry out laboratory test, and
Country rock basic mechanical parameter of the test result obtained by segment of currently constructing after excavation.
Also, the characteristics such as heterogeneous, the discontinuous and anisotropy in view of the tunnel surrounding of soft rock tunnel 1, mechanics ginseng
Number must determine on the basis of test, to ensure that data are accurate and reliable, reduce and calculate error.
In the present embodiment, the spacing in step 2 between the two neighboring tunnel sidewalls support system in front and back be 0.8m~
1.2m。
When practice of construction, according to specific needs, between the tunnel sidewalls support system two neighboring to front and back between
Away from adjusting accordingly.
When progress country rock basic mechanical parameter determines in step 1, identified mechanics parameter includes current constructed segment
The cohesive strength c of tunnel sidewalls Rock Mass, current constructed segment tunnel sidewalls Rock Mass internal friction angleCurrently
The volume-weighted average of the volume-weighted average γ of the tunnel sidewalls Rock Mass of constructed segment, the currently overlying rock of constructed segment
γ0, current constructed segment tunnel sidewalls Rock Mass dilative angle ψ and the current robustness of constructed segment overlying rock
Coefficient f.
Meanwhile also need the excavation width B to soft rock tunnel 1, current constructed segment overlying rock solid coefficient f,
The arch design height h of the Tunnel2, the Tunnel design excavation height h4It is designed with the side wall of the Tunnel high
Spend h3It is determined.
Wherein, the overlying rock of current constructed segment is also referred to as tunnel roof country rock, i.e., country rock above the described Tunnel,
Also referred to as tunnel upper cover layer.
According to general knowledge known in this field, edpth of tunnel refer to top to the natural ground of tunnel excavation section it is vertical away from
From.Herein, the buried depth H of the soft rock tunnel 1 is the vertical distance in the middle part of the arch of the Tunnel to natural ground.
The excavation width in tunnel refers to consider two linings, preliminary bracing, deformation allowance after the maximum of outline excavation excavate
Width.Herein, the excavation width B of soft rock tunnel 1 is also referred to as span, refers to the maximum span of soft rock tunnel 1.
When being determined in step 202 to supporting construction used by the side wall deep support structure, according to outside height
The installation position of the degree opposite side z joist anchor rope 4 is determined and is located at side wall anchor cable 4 in top drawing crack area, wide according to collapsing
The length of the degree opposite side b joist anchor rope 4 is determined and extend out to the front end of side wall anchor cable 4 on the outside of top drawing crack area;
When being determined to supporting construction used by the side wall shallow-layer supporting construction, according to slide surface inclination alpha opposite side
The tilt angle of joist anchor bar 5 is determined, according to inside height h0With the cloth of outside height z and the opposite side collapsing width b joist anchor bar 5
It is wide according to collapsing if position is determined and is laid in the more side wall anchor poles 5 from top to bottom on the lower part slip region
The length of the degree opposite side b joist anchor bar 5 is determined and the front end of the every side wall anchor pole 5 is made to extend out to the lower part slip region
Outside.
For easy construction, when being determined according to the length of the opposite side collapsing width b joist anchor rope 4, the length of the side wall anchor cable 4
Spend L1=l1+L1+l2, wherein l1=0.1m~15cm, l2=0.3m~0.4m, L1 >=1.5b;
When being determined according to the length of the opposite side collapsing width b joist anchor bar 5, the length L of the side wall anchor pole 52=l1+L2+
l2, wherein L2 >=b and L2 < L1.
Wherein, l1And l2Indicate that anchor pole is the length value for ensuring that valid bonding length is reserved to anchor pole or anchor cable both ends.It is practical
In use, l1For any one numerical value within the scope of 0.1m~15cm, l2For any one numerical value within the scope of 0.3m~0.4m.
In the present embodiment, the L1=3b~6b, the L2=1.5b~3b.
In actual use, according to specific needs, the value size of L1 and L2 is adjusted accordingly.
When being determined according to the tilt angle of slide surface inclination alpha opposite side joist anchor bar 5, the inclination angle alpha 1 of side wall anchor pole 5
=180 ° of-α-α0, α0Angle between the slide surface of lower part slip region described in side wall anchor pole 5 and side wall caving zone 3 and 65 °
≤α0≤ 75 °, angle of the α 1 between side wall anchor pole 5 and horizontal plane.
In the present embodiment, α0=69 °.
When practice of construction, according to specific needs, to α0Value size adjust accordingly.
In the present embodiment, the quantity of included side wall anchor pole 5 is three in the supporting construction of side wall shallow-layer described in step 2,
Three side wall anchor poles 5 are in uniformly distributed.
When practice of construction, according to specific needs, the installation position of the quantity of opposite side joist anchor bar 5 and each side wall anchor pole 5 into
The corresponding adjustment of row.
In the present embodiment, side wall anchor cable described in step 24 is located at the middle part in top drawing crack area, the side wall anchor cable
4 and the Tunnel side wall at the top of between spacing be
When practice of construction, according to specific needs, the installation position of opposite side joist anchor rope 4 is adjusted accordingly.
As Figure 1-1, when the tunnel sidewalls are in drawing crack-sliding failure by shear state, side wall caving zone 3 is (i.e.
Right-angled trapezium ABCD) it is the tunnel sidewalls Rock Mass in state of limit equilibrium, BC is potential slide surface, and α inclines for slip-crack surface
Angle (the i.e. described slide surface inclination angle).By the country rock progress force analysis to side wall caving zone 3 it is found that the drawing crack-of tunnel sidewalls
Slide mass (i.e. side wall caving zone 3) is actually the crucial weak structure body in tunnel surrounding, and tunnel is effectively wide after unstability slides
Degree increases (tunnel sidewalls height is increase accordingly), and pole is unfavorable for the stabilization of tunnel vault;In addition, side wall surface wall caving unloading after its
Top concentrates pressure peak to shift to deep, increase the elastic plastic interphase that is formed after side wall deforms to tunnel center away from
From so that the tunnel floor maximal destruction depth and its pucking amount that generate under side wall extruding dramatically increase.Therefore, to side wall into
Timely and effectively supporting has important engineering significance to row.
Also, it is obtained by force analysis, the side wall design height of the Tunnel
When, the sliding failure by shear of drawing crack-will occur in tunnel sidewalls.
In the present embodiment, the average buried depth H=490m of constructed soft rock tunnel 1.The tunnel sidewalls of constructed soft rock tunnel 1
For vertical wall and its height is 4.88m, sagitta 7.2m, excavation width B=14.3m, thus h4=12.08m, h2=7.2m, h3=
4.88m。
It obtains after tested: the cohesive strength c=91kP of the tunnel sidewalls Rock Mass of current constructed segmenta=91 ×
103Pa, the internal friction angle of the tunnel sidewalls Rock Mass of current constructed segmentIt is covered on current constructed segment
The volume-weighted average γ of rock stratum0=21.6kN/m3=21.6 × 103N/m3, the tunnel sidewalls Rock Mass of current constructed segment
Dilative angle ψ=9 °.The solid coefficient f=7.8 of current constructed segment overlying rock.
Also, since constructed soft rock tunnel 1 is deep tunnel, the tunnel sidewalls Rock Mass of 1 two sides of soft rock tunnel by
Power state is identical, thus country rock basic mechanical parameter is carried out in step 1 when determining, scene is bored sample from any one tunnel side
Wall Rock Mass is taken out.In the present embodiment, the volume-weighted average γ of the tunnel sidewalls Rock Mass of current constructed segment=
γ0=21.6 × 103N/m3。
By being calculated, the side wall design height of the TunnelThus tunnel
The sliding failure by shear of drawing crack-will occur in side wall.In intrinsic supporting scheme, tunnel sidewalls use length for the water of 4.0m
Flat grouted anchor bar is not able to satisfy surrouding rock deformation demand for control then, and it is broken that the sliding shearing of drawing crack-inevitably occurs for tunnel sidewalls
It is bad.
The tunnel roof inbreak pitch of arch of the Tunnel
The overlying rock of current constructed segment acts on the well-distributed pressure (also referred to as evenly load) on tunnel sidewalls country rock 2
Q=γ0(h1+h2)=21.6 × 103× (7.2+2.1)=200.9kPa=200.9 × 103Pa。
The slide surface inclination angle of the side wall caving zone 3 of current constructed segment
The inside height of the side wall caving zone 3 of current constructed segment
Outside height
Collapsing width
And originally tunnel sidewalls anchor pole employed in phase supporting scheme is in horizontal layout, such anchor pole and sliding in the tunnel
Face angle theoretical value is 139 °, and angle is excessive, cannot give full play to the anti-shear ability of anchor rod body itself in this way;Also,
Shearing slip after side wall drawing crack can not be limited.Also, due to collapsing width b=0.87m, former side wall rock-bolt length is designed as
4.0m is also theoretically unsound, and easily causes the huge waste of manpower and material resources.
In the present embodiment, the length of side wall anchor cable 4 is 5m, and the length of side wall anchor pole 5 is 2.5m, and side wall anchor pole 5 with
Angle α between the slide surface of lower part slip region described in side wall caving zone 30=69 °, thus anchor rod body can be given full play to certainly
The anti-shear ability of body;Also, side wall anchor pole 5 and the Design of length of side wall anchor cable 4 are reasonable, side wall anchor pole 5 and 4 phase of side wall anchor cable
Cooperation can effectively limit the shearing slip after side wall drawing crack, and not will cause the huge waste of manpower and material resources.
The above is only presently preferred embodiments of the present invention, is not intended to limit the invention in any way, it is all according to the present invention
Technical spirit any simple modification to the above embodiments, change and equivalent structural changes, still fall within skill of the present invention
In the protection scope of art scheme.