CN110821521A - Construction method for excavation and support of hydropower station spillway cavern - Google Patents

Construction method for excavation and support of hydropower station spillway cavern Download PDF

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Publication number
CN110821521A
CN110821521A CN201911121115.5A CN201911121115A CN110821521A CN 110821521 A CN110821521 A CN 110821521A CN 201911121115 A CN201911121115 A CN 201911121115A CN 110821521 A CN110821521 A CN 110821521A
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China
Prior art keywords
layer
construction
excavation
overflow
cavern
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Inventor
何十美
徐少平
马天昌
饶胜斌
苏春生
黄耀文
何克
张星
李向海
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CHINA RAILWAY CONSTRUCTION BRIDGE ENGINEERING BUREAU GROUP OF FIFTH ENGINEERING Co Ltd
China Railway Construction Bridge Engineering Bureau Group Co Ltd
5th Engineering Co Ltd MBEC
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CHINA RAILWAY CONSTRUCTION BRIDGE ENGINEERING BUREAU GROUP OF FIFTH ENGINEERING Co Ltd
China Railway Construction Bridge Engineering Bureau Group Co Ltd
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Priority to CN201911121115.5A priority Critical patent/CN110821521A/en
Publication of CN110821521A publication Critical patent/CN110821521A/en
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    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21DSHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D11/00Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
    • E21D11/04Lining with building materials
    • E21D11/10Lining with building materials with concrete cast in situ; Shuttering also lost shutterings, e.g. made of blocks, of metal plates or other equipment adapted therefor
    • E21D11/105Transport or application of concrete specially adapted for the lining of tunnels or galleries ; Backfilling the space between main building element and the surrounding rock, e.g. with concrete
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02BHYDRAULIC ENGINEERING
    • E02B8/00Details of barrages or weirs ; Energy dissipating devices carried by lock or dry-dock gates
    • E02B8/06Spillways; Devices for dissipation of energy, e.g. for reducing eddies also for lock or dry-dock gates
    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21DSHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D11/00Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
    • E21D11/04Lining with building materials
    • E21D11/10Lining with building materials with concrete cast in situ; Shuttering also lost shutterings, e.g. made of blocks, of metal plates or other equipment adapted therefor
    • E21D11/107Reinforcing elements therefor; Holders for the reinforcing elements
    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21DSHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D11/00Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
    • E21D11/14Lining predominantly with metal
    • E21D11/18Arch members ; Network made of arch members ; Ring elements; Polygon elements; Polygon elements inside arches
    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21DSHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D20/00Setting anchoring-bolts
    • E21D20/003Machines for drilling anchor holes and setting anchor bolts
    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21DSHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D21/00Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection
    • E21D21/0026Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection characterised by constructional features of the bolts

Abstract

The invention discloses a hydropower station spillway cavern excavation supporting construction method, wherein the cavern is divided into an upper layer, a middle layer, a lower layer and a bottom plate protective layer, and the construction method mainly comprises the following steps: step S1: excavating an upper layer, a middle layer and a lower layer of the cavern in sequence; step S2: excavating a drainage hole and performing support construction; step S3: lining a drainage tunnel opening section, grouting construction and bottom plate lining construction; step S4: excavating and supporting a bottom plate of a bottom plate protective layer, and pouring cushion concrete; step S5: and after the cavern enters the hole, the opening construction is provided for the construction branch hole. Aiming at the cavern construction with poor engineering geological conditions, the reasonable and fractional excavation mode is adopted to form a coherent excavation procedure, and the construction is reasonably and hierarchically and fractionally excavated under the condition of ensuring the construction safety, so that the engineering safety is ensured.

Description

Construction method for excavation and support of hydropower station spillway cavern
Technical Field
The invention belongs to the technical field of cavern construction methods, and particularly relates to a hydropower station spillway cavern excavation supporting construction method.
Background
Since the 21 st century, the development and utilization of clean energy in China are in the peak period. A double-river-mouth hydropower station of a great river of Sichuan province is a controlled project for hydropower cascade development of a great river basin, and a hub project comprises a soil-core-wall rock-fill dam, a tunnel-type spillway and the like. The construction area of the cave chamber of the cave-type spillway has no regional fracture and cutting, and the structural deformation is weak. The surface geological mapping and exploration results show that the construction area mainly comprises a series of low-order and low-order minor faults, extrusion fracture zones and joint fracture structural surfaces. The cave body of the cave-type spillway is mainly made of IIIa and IIIb surrounding rocks. When the small fault section is mainly fractured rock, the tunneling condition is poor, the intersection angle with a tunnel line is small, the stability of surrounding rock is unfavorable, faults and influence zones are mainly IV-V type surrounding rock, and a support treatment measure needs to be strengthened. For a section with large buried depth and high ground stress tunnel, the phenomena of rib caving and rock burst can occur in stress release, which brings a serious challenge to construction. The engineering construction analysis of the cave-type spillway is as follows:
1. analysis of engineering conditions
The hole type spillway consists of an inlet channel guiding section, a control gate section, a drainage groove section and an outlet section, wherein the length of the channel guiding section is about 40m, the inlet plane is in an asymmetric trumpet shape, the bottom surface is 2470.00m in elevation, and the minimum width is 16 m. The control gate was provided with 1 hole 16m x 22m (width x height) opening and an open WES type utility weir was used with a weir crest elevation of 2478.00 m. The control gate is provided with an overhaul gate and an arc-shaped working door respectively. The length of the chamber section is 40m, and the height of the top of the gate is 2508.00 m. The discharge section consists of a non-pressure hole section and an open channel section. The pile number of the non-pressure hole is 0+040.00 m-1 +816.00m, the bottom slope i =0.015, the section of the non-pressure hole is of a gate hole type, the width is 17.5-19.3 m, the height is 22.35-27.15 m, and the lining thickness is 1 m. The open trough section consists of two bottom slope sections, wherein the front section bottom slope i =0.015, the pile number overflows 1+816.00 m-1 +935.93m, the rear section bottom slope i =0.462, the pile number overflows 1+947.88 m-2 +107.39m, the two bottom slope sections are connected by a drop sill, a horizontal section and an arc, the section of the open trough is rectangular, the width of the trough is 16m, and the height of a side wall is 12 m-16 m. The concrete thickness of the bottom plate of the exposed groove is 2.0m, and the top width of the left side wall and the right side wall is 2.0 m. The outlet section consists of a flip bucket section and a downstream protection section, the outlet adopts flip flow energy dissipation, and the flip bucket adopts a chamfered nose bucket type. In order to ensure that the water flow is well regulated and prevent the water flow from scouring the downstream bank slope, expanding excavation is respectively adopted for the bank and the opposite bank, and concrete slope protection is adopted within a certain range.
2. Engineering geological analysis
(1) Overflow 0+040.00 m-overflow 0+073.00m, length 33.00m, hole direction N85 degree 8 '46' E, vertical buried depth 80 m-108 m, surrounding rock is hard two-cloud two-long granite, no big fault passes, four groups of fractures mainly develop, J1.N20-35 degree W/NE ∠ -40 degree, J2.N40-50 degree E/NW ∠ -56 degree, J3.N20-35 degree W/SW ∠ -40-55 degree, J4.N75 degree W/NE ∠ degree.
(2) The length of the overflow zone is 1350m, the hole direction is N85 degrees 8 '46' E, the vertical burial depth is 80 m-500 m, the surrounding rock is mainly hard two-cloud two-long granite, pegging pegmatite veins, the two generally are in welding contact, no large fault passes through the rock mass, the dominant fractures are four groups, namely J1.N20-35 degrees W/NE ∠ 25-40 degrees, J2.N40-50 degrees E/NW ∠ 40-56 degrees, J3.N20 degrees W/SW ∠ 40-55 degrees, J4.N75 degrees W/NE ∠ 84 degrees, the rock mass is slightly weathered and fresh, the underground water is not abundant, local water seepage occurs, occasional linear water flows are happened, the rock mass is in an integral structure, after considering high ground stress reduction, the surrounding rock is mainly in a construction, the tunneling condition is better, the random fault is small in the surrounding rock, when the surrounding rock mass and the joint fractures are cut mutually to form a block, the block is probably penetrated deeply, and the problem of water burst treatment and the block is probably caused, and the problem of the construction is probably caused when the construction is solved.
(3) The length of the overflow zone is 113m to 1+536m, the length of the overflow zone is N85 degrees 8 '46' E, the vertical buried depth is 80m to 100m, the surrounding rock is mainly hard Doudishui long granite, pegging pegmatite veins, the two mainly are in welding contact, no large fault passes through the rock mass, the dominant fractures are four groups, namely J1.N20-35 degrees W/NE ∠ 25-40 degrees, J2.N40-50 degrees E/NW ∠ 40-56 degrees, J3.N20 degrees W/SW ∠ 40-55 degrees, J4.N75 degrees W/NE ∠ 84 degrees, the rock mass is slightly weathered and fresh, the underground water is not abundant, local water seepage and occasional linear water flowing are happened, the blocky to integral structure is considered, the surrounding rock mass mainly takes II type construction, the tunneling condition is better, the problem is that small faults in the surrounding rock are randomly distributed and burst with the joint fractures to form blocks when high ground stress is considered, the problem that the surrounding rock mass is likely to pass through deep buried zones and the supporting zone is likely to be broken, and the problem of water breaking is likely to be caused.
(4) Overflow 1+536 m-overflow 1+816.0 m: the length is 280m, the hole is towards N85 degrees 8 '46' E, and the vertical buried depth is 49 m-133 m. The surrounding rock is mainly hard Duyun-Er-Chang granite and developed giant crystal veins, most rock masses are slightly weathered to fresh, the part of the rock masses is weak unloading and weak weathering lower-stage rock masses, underground water in the rock masses is not abundant, mainly seepage water is mainly used, and local linear running water is generated. The rock mass is in a secondary block-block structure, the surrounding rock mainly comprises IIIa class, and local IIIb class, and the tunneling condition is better. Attention should be paid to the problem of unfavorable combination of randomly distributed minor faults and joint fractures, and support measures should be strengthened. And the local hole section can have rock burst phenomenon, and preventive measures should be taken.
Disclosure of Invention
The invention aims to provide a hydropower station spillway cavern excavation supporting construction method, which aims at cavern construction with poor engineering geological conditions, adopts a reasonable subsection excavation mode to form a coherent excavation procedure, and reasonably performs layering and subsection excavation construction under the condition of ensuring construction safety so as to ensure engineering safety.
The invention is mainly realized by the following technical scheme: a hydropower station spillway cavern excavation supporting construction method comprises the following steps that:
step S1: excavating an upper layer, a middle layer and a lower layer of the cavern in sequence;
step S2: excavating a drainage hole and performing support construction;
step S3: lining a drainage tunnel opening section, grouting construction and bottom plate lining construction;
step S4: excavating and supporting a bottom plate of a bottom plate protective layer, and pouring cushion concrete;
step S5: and after the cavern enters the hole, the opening construction is provided for the construction branch hole.
In order to better realize the method, further, the excavation of the cavern is performed in the sequence of from top to bottom, from inside to outside, from right to back and from left to right; the upper layer adopts a construction method of expanding excavation at the leading two sides of a pilot tunnel and peripheral smooth blasting; the middle layer and the lower layer are excavated by adopting presplitting blasting, the side walls on two sides form an excavation contour line by adopting presplitting blasting, the middle part adopts stepped differential blasting, and a protective layer with the thickness of 1.5m is reserved on the bottom plate; and (5) excavating the bottom plate protective layer by adopting a horizontal light blasting hole for construction.
In order to better realize the invention, further, the upper layer is divided into a middle area and two side areas, firstly, the upper layer pilot tunnel of the middle area is excavated, and the width and the height of the middle area are 8m and 8 m; then, excavating and supporting construction are carried out on two sides of the upper pilot tunnel of the two side areas, and the distance between the tunnel face of the pilot tunnel is lagged by 30 m.
In order to better implement the invention, further, the middle layer lags the upper layer by 200m-300 m; the middle layer is divided into a left area and a right area, and excavation alternately advances at an interval of 150 m; the road repair from the middle layer to the upper layer needs two steps, the height of the step is 4.28m, the gradient is 25%, the length is 34.2m, and the slag filling amount is 586m3
In order to better implement the invention, further, the lower layer lags the middle layer by 200m-300 m; the lower layer is divided into a left area and a right area, and excavation alternately advances at an interval of 150 m; the road repair from the lower layer to the middle layer needs two steps, the height of the step is 4.25m, the gradient is 25%, the length is 34m, and the slag filling amount is 578m3
In order to better implement the present invention, in step S4, after the lower layer excavation is completed, the boundary overflow 0+908 is performed, and the two working surfaces of the entrance and the exit are simultaneously constructed.
In order to better implement the present invention, further, the step S5 mainly includes the following steps:
step S501: after the upper layer is excavated to overflow 0+200, the right side begins to descend to the middle layer from the pile number overflow 0+072.5 to overflow 0+129.5, the slope is 15% and the descending slope length is 57m, when the excavation is continued to advance to overflow 0+229.5, the slope is started to climb to the upper layer overflow 0+263.7, then the left side of the upper layer begins to descend to the middle layer from the pile number overflow 0+072.5 to overflow 0+129.5, the slope is 15% and the descending slope length is 57m, when the excavation is continued to advance to overflow 0+229.5, the slope is started to climb to the upper layer overflow 0+263.7, and the middle layer excavation is alternately excavated in different regions from overflow 0+ 263.7;
step S502: the right side of the middle layer reversely descends from the position of pile number overflow 0+178.5 to the position of pile number overflow 0+111.8, the excavation is carried out with a bottom plate protective layer, the slope is 15%, the descending length is 66.7m, the excavation is continuously carried out to the position of overflow 0+072.5, the number of the pile at the junction of the 1# construction branch tunnel and the main tunnel is overflow 0+100, and the tunnel exit condition is met;
step 503: after the construction of the No. 1 construction branch tunnel is completed, excavating from the overflow 0+129.5 position to the overflow 0+072.5 position on the left side of the middle layer before the side and upward slope movement, reversely descending the slope from the pile number overflow 0+178.5 position to the pile number overflow 0+111.5 position on the left side of the middle layer after the completion, excavating with a bottom plate protective layer, continuously excavating to the overflow 0+072.5 position with the slope of 15% and the descending length of 66.7m, and starting to advance according to the regional alternate excavation of the lower layer;
step S504: and the sections from 0+042.5 overflow to 0+072.5 overflow of the middle and lower layers are excavated from the outside of the tunnel to the inside of the tunnel when the side and top slopes of the tunnel are excavated, so that the structure of the tunnel mouth section of the spillway is safe when earth and stones outside the tunnel are excavated.
In order to better realize the invention, further, the temporary supporting construction of the tunnel body comprises the following steps: c22 is randomly arranged in the range of the II-type surrounding rock side top arch, L =3m anchor rods are arranged, and C25 concrete is sprayed; c25 is randomly arranged in the range of the III-type surrounding rock side top arch, anchor rods with the length of L =4.5m are sprayed with C25 concrete; c28 bolts are randomly arranged in the range of IV and V type surrounding rock side roof arches, L =6m anchor rods are arranged, and C25 concrete is sprayed. L is the length of the anchor rod.
In order to better implement the invention, further, the temporary supporting construction of the tunnel body mainly comprises the following steps:
step S100: constructing an anchor rod; drilling the anchor rod by using a three-arm drill and a YT-28 drilling machine; the bore diameter of the mortar anchor rod is larger than the diameter of the anchor rod, and the requirement of construction drawings is met; when the construction drawing is not specified, for the grouting anchor rod, if the procedure of firstly grouting and then installing the anchor rod is adopted for construction, the diameter of the drill bit is more than 15mm larger than the diameter of the anchor rod; if the procedure of installing the anchor rod firstly and then grouting is adopted for construction, the diameter of the drill bit is more than 25mm larger than the diameter of the anchor rod, and the diameter of the drill bit is more than 40mm larger than the diameter of the anchor rod when hole bottom grouting is adopted; arranging anchor rod holes according to construction drawings, wherein the deviation of the hole positions is not more than 15 cm;
step S200: constructing a reinforcing mesh; during construction of the reinforcing bar mesh, a transport vehicle handle is welded into a reinforcing bar mesh sheet with the width and the length of 1.5m in a reinforcing bar processing field and is transported to a working surface, an operator takes a support rack as an operation platform and firmly welds the reinforcing bar mesh with the anchor rod and the joint of the inserted bars so as to fix the reinforcing bar mesh on a rock surface, and the distance between the reinforcing bar mesh and the rock surface is 3-5 cm;
step S300: carrying out concrete spraying construction; when in spraying, the distance between the spray head and the rock surface is 0.6 m-1.2 m, and the spray head is vertical to the sprayed surface and does continuous circular motion so as to ensure that the concrete is sprayed compactly; when in injection, the air pressure, the water pressure and the injection distance are mastered and the rebound quantity is reduced according to the sequence of segmenting and partitioning, namely wall first, arch later and bottom-up; after the sprayed concrete is finally set for 2 hours, carrying out water spraying maintenance for 14 days or more; when the concrete is sprayed and the excavation is synchronously constructed, the interval between the next blasting time and the concrete spraying completion time is more than or equal to 4 hours;
step S400: and (5) constructing a steel arch frame.
The invention has the following beneficial effects:
(1) aiming at the cavern construction with poor engineering geological conditions, the invention adopts a reasonable and fractional excavation mode to form a coherent excavation procedure, and reasonably performs layered and fractional excavation construction under the condition of ensuring the construction safety so as to ensure the engineering safety.
(2) The invention ensures that the safety of the chamber supporting structure also meets the requirement of engineering economy. The parameters of the engineering structure can provide relevant engineering experience reference for subsequent similar engineering.
(3) The invention takes the excavation of the spillway chambers of hydropower stations with double river mouths at the upstream of a great river as a background, and researches the construction control technology of chamber excavation support under the complex geological condition. Firstly, engineering conditions and engineering geology are comprehensively analyzed, an excavation method of six-layer excavation with upper, middle and lower layers is provided, and the excavation sequence from top to bottom, from inside to outside, right first and left second is determined. In the construction of the supporting structure, the corresponding supporting structure and the corresponding construction process are determined according to the geological condition on the spot, and a foundation is laid for the successful construction of the engineering.
Drawings
FIG. 1 is a schematic view of a layered and divided excavation sequence of a spillway cavern;
FIG. 2 is a schematic view of the upper, middle and lower layers of spillway caverns and the excavation of the bottom plate protective layer;
FIG. 3 is a schematic diagram of the middle and lower level road planning in the spillway cavern;
FIG. 4 is a schematic view of the construction relationship between the spillway cavern and the No. 1 construction branch cavern;
FIG. 5 is a schematic view of the spatial relationship between the spillway cavern and the No. 1 construction branch cavern;
FIG. 6 is a flow chart of the anchor rod construction process;
FIG. 7 is a flow chart of a wet shotcrete process;
FIG. 8 is a flow chart of steel arch construction process.
Detailed Description
Example 1:
a hydropower station spillway cavern excavation supporting construction method mainly comprises the following steps:
step S1: excavating an upper layer, a middle layer and a lower layer of the cavern in sequence;
step S2: excavating a drainage hole and performing support construction;
step S3: lining a drainage tunnel opening section, grouting construction and bottom plate lining construction;
step S4: excavating and supporting a bottom plate of a bottom plate protective layer, and pouring cushion concrete;
step S5: and after the cavern enters the hole, the opening construction is provided for the construction branch hole.
The invention takes the excavation of the spillway chambers of hydropower stations with double river mouths at the upstream of a great river as a background, and researches the construction control technology of chamber excavation support under the complex geological condition. Firstly, engineering conditions and engineering geology are comprehensively analyzed, an excavation method of six-layer excavation with upper, middle and lower layers is provided, and the excavation sequence from top to bottom, from inside to outside, right first and left second is determined. In the construction of the supporting structure, the corresponding supporting structure and the corresponding construction process are determined according to the geological condition on the spot, and a foundation is laid for the successful construction of the engineering. Aiming at the cavern construction with poor engineering geological conditions, the reasonable and fractional excavation mode is adopted to form a coherent excavation procedure, and the construction is reasonably and hierarchically and fractionally excavated under the condition of ensuring the construction safety, so that the engineering safety is ensured.
Example 2:
a hydropower station spillway cavern excavation supporting construction method mainly comprises the following steps:
1. main technical requirements for construction
The chamber mileage of the cave-type spillway: overflow 0+ 042.00-overflow 1+816.00, length 1774m, longitudinal gradient i =0.015 of the bottom plate, and excavation section 17.5m × 22.35 m-19.3 m × 27.15m is divided into 5 excavation section forms.
Excavating the cavern by four layers of upper, middle, lower and bottom plate protective layers; the upper layer adopts a construction method of 'expanding excavation at the front two sides of a pilot tunnel' and peripheral smooth blasting; the middle and lower layers are excavated by adopting presplitting blasting, the side walls on two sides are subjected to presplitting blasting to form an excavation contour line, the middle part is subjected to stepped differential blasting, and a protective layer with the thickness of 1.5m is reserved on the bottom plate; and (5) excavating the bottom plate protective layer by adopting a horizontal light blasting hole for construction.
And (3) support engineering: the anchor rod of the system + the hanging reinforcing mesh A6.5@15cm + the concrete of c25 spraying, the thickness is 15 cm; and supporting a section of surrounding rock crushing section by a vertical steel arch frame for reinforcing support.
2. Main construction process
The main construction process of excavation and support construction of the cave-type spillway chamber is as follows, and the schematic diagram of the layered and subsection excavation sequence of the cave body of the cave-type spillway is shown in figure 1.
(1) ① area upper pilot tunnel excavation and support construction (8 m by 8m, width by height);
(2) expanding, digging and supporting construction (lagging pilot tunnel face 30 m) at two sides of the upper pilot tunnel in the No. ② area;
(3) the middle layer is divided into two areas, namely an ③ area and a ④ area, when excavation and supporting construction is carried out (the middle layer lags behind the upper layer by 200m-300 m), the excavation of the ③ area and the ④ area alternately advances, the interval is 150m alternately, so that delay time of repeated road repair is avoided, the road repair from the middle layer to the upper layer needs 2 steps, the height of each step is 4.28m, the gradient is 25%, the length is 34.2m, and the slag filling amount is 586 m;
(4) the lower layer is divided into two regions, namely an ⑤ region and a ⑥ region, when excavation and support construction is carried out (the lower layer lags the middle layer by 200m-300 m), the ⑤ region and the ⑥ region are alternately carried out at intervals of 150m so as to avoid delay time of repeated road repair, the road repair from the lower layer to the middle layer is divided into 2 steps, the height of each step is 4.25m, the gradient is 25%, the length is 34m, and the slag filling amount is 578m for carrying out the arc construction;
(5) excavating and supporting construction of drainage holes (excavating and supporting the lower layer of the cave-type spillway to corresponding mileage of the drainage holes in 2017, 12 months and 25 days);
(6) lining a drainage tunnel opening section, grouting construction and bottom plate lining construction;
(7) ⑦ construction of floor excavation, supporting and cushion concrete pouring (construction is started after lower floor excavation is completed), two working faces of an inlet and an outlet are constructed simultaneously from an overflow 0+908 boundary, tunnel spillway layering and floor protection layer excavation division are shown in figure 2, tunnel spillway upper, middle and lower and floor protection layer excavation division schematic diagrams, and spillway middle and lower floor road planning is shown in figure 3.
(8) After entering the cave, the cave chamber of the cave type spillway provides a cave exit construction process for the construction branch cave:
after the upper layer of the cave-type spillway is excavated to overflow 0+200, the right side starts to descend to the middle layer from the pile number overflow 0+072.5 to overflow 0+129.5 (the gradient is 15%, the descending length is 57 m), then the excavation continues to advance to overflow 0+229.5, the slope starts to climb to the upper layer overflow 0+263.7, then the left side of the upper layer starts to descend to the middle layer from the pile number overflow 0+072.5 to overflow 0+129.5 (the gradient is 15%, the descending length is 57 m), the excavation continues to advance to overflow 0+229.5, the slope starts to climb to overflow 0+263.7, and the middle layer excavation alternately excavates and excavates from the overflow 0+263.7 area to ③ area and the ④ area.
And (3) when the right side of the middle layer reversely descends from the position of pile number overflow 0+178.5 to the position of pile number overflow 0+111.8 (including the excavation of the bottom plate protective layer, the slope is 15 percent and the descending length is 66.7 m), the middle layer continues to be excavated to the position of overflow 0+072.5, the number of the pile at the junction of the 1# construction branch tunnel and the main tunnel is overflow 0+100, and the exit condition is met at the moment.
After the construction of the No. 1 construction branch tunnel is completed, the left side of the middle layer is excavated from the position of 0+129.5 overflow to the position of 0+072.5 overflow, the left side of the middle layer is excavated continuously to the position of 0+072.5 overflow when the left side of the middle layer is reversely descended from the position of 0+178.5 pile number overflow to the position of 0+111.5 pile number overflow (including the excavation of a bottom plate protective layer, the slope is 15 percent and the descending length is 66.7 m), and the lower layer is excavated alternately according to the ⑤ and ⑥ areas and advances.
And the sections from 0+042.5 overflow to 0+072.5 overflow of the middle and lower layers are excavated from the outside of the tunnel to the inside of the tunnel when the tunnel is excavated on the side and upward slope, so that the structure of the tunnel mouth section of the spillway is safe when earth and stones outside the tunnel are excavated, the excavation sequence of the No. 1 branch tunnel is shown in figure 4, and the spatial relationship diagram of the tunnel spillway and the No. 1 construction branch tunnel is shown in figure 5.
Example 2:
the embodiment is optimized on the basis of embodiment 1 or 2, and the construction method of the hole body supporting structure mainly comprises the following steps:
the principle of the system support of the tunnel body is that the system support closely follows a tunnel face, in a better surrounding rock tunnel section, in order to accelerate construction progress, the system support can lag the tunnel face for a certain distance, and in principle, the system support does not exceed 30m, can be unfolded and excavated to be operated in parallel, but the system support is prevented from lagging the tunnel face for a longer distance. And (3) temporary supporting construction of the tunnel body: c22 is randomly arranged in the range of the II-type surrounding rock side top arch, L =3m anchor rods are arranged, and C25 concrete is sprayed; c25 is randomly arranged in the range of the III-type surrounding rock side top arch, anchor rods with the length of L =4.5m are sprayed with C25 concrete; c28 bolts are randomly arranged in the range of IV and V type surrounding rock side roof arches, L =6m anchor rods are arranged, and C25 concrete is sprayed.
(1) Anchor rod construction
The anchor rod construction process flow is shown in fig. 6 and mainly comprises the following steps:
preparation for construction
Measuring and lofting, arranging holes according to design, and marking the positions of anchor rod holes on the rock wall by using red paint; the three-arm drill, the YT-28 drilling machine and the constructor are ready; the wind, water and electricity are connected, the air compressor is started to supply air, the water pump is started to supply water, and the power supply is started to provide illumination.
Drilling construction
Drilling the anchor rod by using a three-arm drill and a YT-28 drilling machine; the hole diameter of the mortar anchor rod is larger than the diameter of the anchor rod, and the requirement of construction drawings is met. When the construction drawing is not specified, for a grouting anchor rod, if the procedure of grouting first and then installing the anchor rod is adopted for construction, the diameter of a drill bit is more than 15mm larger than the diameter of the anchor rod; if the procedure of 'installing the anchor rod firstly and then grouting' is adopted for construction, the diameter of the drill bit is more than 25mm of the diameter of the anchor rod, and the diameter of the drill bit is more than 40mm of the diameter of the anchor rod when grouting is adopted at the bottom of the hole.
The anchor rod holes are arranged according to construction drawings, and the deviation of the hole positions is not more than 15 cm.
Setting and grouting of anchor rods
Before the anchor rod is installed or grouted, high-pressure wind and water are used to wash the anchor rod hole to ensure no stone powder left in the hole. Grouting by adopting a professional high-pressure grouting pump; the inserted bar is manually matched with the inserted bar of a crane, and finally a backing plate is installed and is firmly fixed by a nut.
(2) Construction of reinforcing mesh
During construction of the reinforcing bar net, a transportation handle is used for welding the reinforcing bar net piece with the width being 1.5m by 1.5m (width by length) in a reinforcing bar processing field and transporting the reinforcing bar net piece to a working surface, an operator uses a support rack as an operation platform to firmly weld the connecting parts of the reinforcing bar net, the anchor rods and the inserted bars so as to fix the reinforcing bar net piece on a rock surface, and the distance between the reinforcing bar net and the rock surface is 3-5 cm.
(3) Shotcrete construction
The wet shotcrete process flow is shown in fig. 7, and mainly comprises the following steps:
preparation for construction
Before spraying concrete, carefully checking the section size of the tunnel, cleaning and treating the underexcavated part and all cracked, crushed, discharged and disintegrated damaged rocks, removing pumice and wall corner virtual slag, and washing the rock surface by using high-pressure water or wind.
Mixing stations, concrete transport vehicles, constructors, wet spraying machines and guniting trolleys are ready; the wind, water and electricity are connected, the air compressor is started to supply air, the water pump is started to supply water, and the power supply is started to provide illumination.
Shotcrete construction
The sprayed concrete adopts a wet spraying method, a mixing station mixes the concrete, a concrete tank truck transports the concrete, and a wet spraying machine sprays the concrete. The method comprises two procedures of primary spraying and secondary spraying during spraying, wherein primary spraying is immediately carried out on exposed surrounding rocks after each circulation of excavation is finished; after the anchor rod, the reinforcing mesh and other processes are finished, re-spraying is carried out.
The technical requirements of the sprayed concrete are as follows: when in spraying, the distance between the spray head and the rock surface is preferably 0.6-1.2 m, and the spray head is vertical to the sprayed surface and does continuous circular motion so as to ensure that the concrete is sprayed compactly; when in injection, the air pressure, the water pressure and the injection distance are mastered and the rebound quantity is reduced according to the sequence of segmenting and partitioning, namely wall first, arch later and bottom-up; after the sprayed concrete is finally set for 2 hours, carrying out water spraying maintenance for not less than 14 days; and when the sprayed concrete and the excavation are synchronously constructed, the interval between the next blasting time and the concrete spraying completion time is not less than 4 h.
(4) Construction of steel arch frame
And (3) processing and forming the steel arch centering in a factory, assembling the steel arch centering in a trial mode to be qualified, transporting the steel arch centering to a construction working face by a transport vehicle after the limbs are separated, and mechanically matching with manual installation.
As shown in fig. 8, before the steel arch construction, a measurer checks the section condition by using a measuring instrument, and the underexcavated section is processed in advance; during steel arch construction, a measuring instrument is used for measuring and positioning the steel frame, an operator places and adjusts the steel frame in place according to the indication of the measuring instrument, then a locking anchor rod is hammered, connecting ribs are welded, a reinforcing mesh is laid, and concrete is sprayed to fill the gap between the steel arch and the rock surface and cover the steel arch.
Before each process is constructed, a supervision engineer is required to be timely reported to enter the next process for construction after the supervision engineer checks and accepts the inspection; and the work of checking and accepting the quality of the upper layer support must be finished before the middle layer is excavated.
The invention takes the excavation of the spillway chambers of hydropower stations with double river mouths at the upstream of a great river as a background, and researches the construction control technology of chamber excavation support under the complex geological condition. Firstly, engineering conditions and engineering geology are comprehensively analyzed, an excavation method of six-layer excavation with upper, middle and lower layers is provided, and the excavation sequence from top to bottom, from inside to outside, right first and left second is determined. In the construction of the supporting structure, the corresponding supporting structure and the corresponding construction process are determined according to the geological condition on the spot, and a foundation is laid for the successful construction of the engineering. Aiming at the cavern construction with poor engineering geological conditions, the reasonable and fractional excavation mode is adopted to form a coherent excavation procedure, and the construction is reasonably and hierarchically and fractionally excavated under the condition of ensuring the construction safety, so that the engineering safety is ensured.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and all simple modifications and equivalent variations of the above embodiments according to the technical spirit of the present invention are included in the scope of the present invention.

Claims (9)

1. The excavation and supporting construction method for the cavern of the spillway of the hydropower station is characterized in that the cavern is divided into four layers, namely an upper layer, a middle layer, a lower layer and a bottom plate protective layer, and mainly comprises the following steps:
step S1: excavating an upper layer, a middle layer and a lower layer of the cavern in sequence;
step S2: excavating a drainage hole and performing support construction;
step S3: lining a drainage tunnel opening section, grouting construction and bottom plate lining construction;
step S4: excavating and supporting a bottom plate of a bottom plate protective layer, and pouring cushion concrete;
step S5: and after the cavern enters the hole, the opening construction is provided for the construction branch hole.
2. The hydropower station spillway cavern excavation supporting construction method of claim 1, wherein the cavern excavation is performed in the order of from top to bottom, from inside to outside, right to back and left; the upper layer adopts a construction method of expanding excavation at the leading two sides of a pilot tunnel and peripheral smooth blasting; the middle layer and the lower layer are excavated by adopting presplitting blasting, the side walls on two sides form an excavation contour line by adopting presplitting blasting, the middle part adopts stepped differential blasting, and a protective layer with the thickness of 1.5m is reserved on the bottom plate; and (5) excavating the bottom plate protective layer by adopting a horizontal light blasting hole for construction.
3. The hydropower station spillway cavern excavation supporting construction method as claimed in claim 2, wherein the upper layer is divided into a middle area and two side areas, the upper pilot tunnel in the middle area is firstly excavated, and the width and the height of the middle area are 8m to 8 m; then, excavating and supporting construction are carried out on two sides of the upper pilot tunnel of the two side areas, and the distance between the tunnel face of the pilot tunnel is lagged by 30 m.
4. The construction method for excavation and support of the spillway cavern of the hydropower station according to claim 3, wherein the middle layer lags behind the upper layer by 200-300 m; the middle layer is divided into a left area and a right area, and excavation alternately advances at an interval of 150 m; the road repair from the middle layer to the upper layer needs two steps, the height of the step is 4.28m, the gradient is 25%, the length is 34.2m, and the slag filling amount is 586m3
5. The hydropower station spillway cavern excavation supporting construction method as claimed in claim 4, wherein the lower-layer lagging middle layer is 200-300 m; the lower layer is divided into a left area and a right area, and excavation alternately advances at an interval of 150 m; the road repair from the lower layer to the middle layer needs two steps, the height of the step is 4.25m, the gradient is 25%, the length is 34m, and the slag filling amount is 578m3
6. The method for supporting the excavation of the spillway cavern of the hydropower station according to claim 2, wherein in the step S4, after the lower layer excavation is completed, the boundary of overflow 0+908 is formed, and an inlet and an outlet are constructed simultaneously.
7. The construction method for excavation and support of the spillway cavern of the hydropower station according to claim 1, wherein the step S5 mainly comprises the following steps:
step S501: after the upper layer is excavated to overflow 0+200, the right side begins to descend to the middle layer from the pile number overflow 0+072.5 to overflow 0+129.5, the slope is 15% and the descending slope length is 57m, when the excavation is continued to advance to overflow 0+229.5, the slope is started to climb to the upper layer overflow 0+263.7, then the left side of the upper layer begins to descend to the middle layer from the pile number overflow 0+072.5 to overflow 0+129.5, the slope is 15% and the descending slope length is 57m, when the excavation is continued to advance to overflow 0+229.5, the slope is started to climb to the upper layer overflow 0+263.7, and the middle layer excavation is alternately excavated in different regions from overflow 0+ 263.7;
step S502: the right side of the middle layer reversely descends from the position of pile number overflow 0+178.5 to the position of pile number overflow 0+111.8, the excavation is carried out with a bottom plate protective layer, the slope is 15%, the descending length is 66.7m, the excavation is continuously carried out to the position of overflow 0+072.5, the number of the pile at the junction of the 1# construction branch tunnel and the main tunnel is overflow 0+100, and the tunnel exit condition is met;
step 503: after the construction of the No. 1 construction branch tunnel is completed, excavating from the overflow 0+129.5 position to the overflow 0+072.5 position on the left side of the middle layer before the side and upward slope movement, reversely descending the slope from the pile number overflow 0+178.5 position to the pile number overflow 0+111.5 position on the left side of the middle layer after the completion, excavating with a bottom plate protective layer, continuously excavating to the overflow 0+072.5 position with the slope of 15% and the descending length of 66.7m, and starting to advance according to the regional alternate excavation of the lower layer;
step S504: and the sections from 0+042.5 overflow to 0+072.5 overflow of the middle and lower layers are excavated from the outside of the tunnel to the inside of the tunnel when the side and top slopes of the tunnel are excavated, so that the structure of the tunnel mouth section of the spillway is safe when earth and stones outside the tunnel are excavated.
8. The hydropower station spillway cavern excavation supporting construction method according to claim 1, characterized in that a cavern body temporary supporting construction method comprises the following steps: c22 is randomly arranged in the range of the II-type surrounding rock side top arch, L =3m anchor rods are arranged, and C25 concrete is sprayed; c25 is randomly arranged in the range of the III-type surrounding rock side top arch, anchor rods with the length of L =4.5m are sprayed with C25 concrete; c28 bolts are randomly arranged in the range of IV and V type surrounding rock side roof arches, L =6m anchor rods are arranged, and C25 concrete is sprayed.
9. The hydropower station spillway cavern excavation supporting construction method according to claim 8, wherein the temporary supporting construction of the cavern body mainly comprises the following steps:
step S100: constructing an anchor rod; drilling the anchor rod by using a three-arm drill and a YT-28 drilling machine; the bore diameter of the mortar anchor rod is larger than the diameter of the anchor rod, and the requirement of construction drawings is met; when the construction drawing is not specified, for the grouting anchor rod, if the procedure of firstly grouting and then installing the anchor rod is adopted for construction, the diameter of the drill bit is more than 15mm larger than the diameter of the anchor rod; if the procedure of installing the anchor rod firstly and then grouting is adopted for construction, the diameter of the drill bit is more than 25mm larger than the diameter of the anchor rod, and the diameter of the drill bit is more than 40mm larger than the diameter of the anchor rod when hole bottom grouting is adopted; arranging anchor rod holes according to construction drawings, wherein the deviation of the hole positions is not more than 15 cm;
step S200: constructing a reinforcing mesh; during construction of the reinforcing bar mesh, a transport vehicle handle is welded into a reinforcing bar mesh sheet with the width and the length of 1.5m in a reinforcing bar processing field and is transported to a working surface, an operator takes a support rack as an operation platform and firmly welds the reinforcing bar mesh with the anchor rod and the joint of the inserted bars so as to fix the reinforcing bar mesh on a rock surface, and the distance between the reinforcing bar mesh and the rock surface is 3-5 cm;
step S300: carrying out concrete spraying construction; when in spraying, the distance between the spray head and the rock surface is 0.6 m-1.2 m, and the spray head is vertical to the sprayed surface and does continuous circular motion so as to ensure that the concrete is sprayed compactly; when in injection, the air pressure, the water pressure and the injection distance are mastered and the rebound quantity is reduced according to the sequence of segmenting and partitioning, namely wall first, arch later and bottom-up; after the sprayed concrete is finally set for 2 hours, carrying out water spraying maintenance for 14 days or more; when the concrete is sprayed and the excavation is synchronously constructed, the interval between the next blasting time and the concrete spraying completion time is more than or equal to 4 hours;
step S400: and (5) constructing a steel arch frame.
CN201911121115.5A 2019-11-15 2019-11-15 Construction method for excavation and support of hydropower station spillway cavern Pending CN110821521A (en)

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