Excavation method for large-span spherical dome

Abstract

The invention is a large-span spherical dome excavation method, which solves the problems of difficult drilling control, poor drilling accuracy and poor safety in the cross excavation method, fan-shaped strip method and circular middle column method for the spherical surface of the dome. By using the existing construction access tunnel to enter the spherical dome area, continue to excavate the horizontal pilot tunnel forward. At the end of the horizontal pilot tunnel, that is, in the axial direction of the spherical dome, excavate the middle vertical pilot tunnel. After the middle vertical pilot tunnel is excavated to the spherical dome, immediately construct the dome middle crown bolts and shotcrete layer, and then excavate the surrounding area of the dome. First, excavate the surrounding area of the first dome to form a spherical surface, and then excavate the first reserved protective layer near the spherical surface. When excavating the first reserved protective layer, drill holes obliquely from the center to the surrounding along the dome circular surface, charge and blast for excavation. After excavating the first reserved protective layer, rake the stone slag to the bottom of the middle vertical pilot tunnel, and repeat the above steps for the excavation and support of the surrounding area of the lower dome and its reserved protective layer until all the excavation and support are completed.

Description

Technical Field

[0001] The present invention relates to the field of underground chamber excavation construction, especially the excavation construction method for large-span spherical domes. Background Art

[0002] In underground engineering buildings such as hydropower stations, spherical domes are often designed, that is, underground chambers with spherical curved roof arches, such as the surge shafts and vortex wells of hydropower stations. The construction methods for the dome part mainly include the cross excavation method, the fan-shaped strip method, the circular middle column method, etc. When constructing, horizontal holes need to be drilled along the spherical curved surface of the dome. Since the drilling depths and angles are different at different heights of the spherical curved surface of the dome, it is difficult to control the drilling, the drilling accuracy is poor, and it affects the excavation forming quality of the spherical curved surface of the dome. At the same time, when excavating the reserved rock pillars, the excavation span increases significantly, resulting in a large increase in the deformation of the surrounding rock and a high safety risk. Summary of the Invention

[0003] The purpose of the present invention is to provide an excavation method for large-span spherical domes with easy drilling control, high drilling accuracy, stable large-span domes, and safe dome construction.

[0004] The purpose of the present invention is achieved as follows:

[0005] For the excavation method of large-span spherical domes, use the existing construction access tunnel to enter the spherical dome part, and continue to excavate the horizontal pilot tunnel 1 forward. At the terminal of the horizontal pilot tunnel, that is, the central axis of the spherical dome, excavate the middle vertical pilot tunnel 2 upward. After the middle vertical pilot tunnel is excavated to the spherical dome, immediately construct the dome middle roof arch anchor bolts 3 and the shotcrete layer 4. Then excavate the surrounding area of the dome. When excavating, use the method of reserving a protective layer and excavating the surrounding area of the dome in layers. First, excavate the first surrounding area of the dome 6 to form a spherical curved surface, and then excavate the first reserved protective layer 9 near the spherical curved surface. When excavating the first reserved protective layer near the spherical curved surface of the dome, drill holes obliquely from the center to the periphery along the circular curved surface of the dome, charge and blast for excavation. After excavating the first reserved protective layer, rake the stone slag to the bottom of the middle vertical pilot tunnel, and transport the stone slag to the slag yard by truck. Timely support the spherical curved surface of the dome that has been excavated with anchor bolts and shotcrete layer according to the geological conditions revealed by the excavation. Then repeat the above steps to successively carry out the excavation and support of the second - Nth surrounding area of the dome and its second - Nth reserved protective layer until all the excavation and support are completed.

[0006] After the middle vertical pilot tunnel 2 is excavated, timely support the roof arch part of the dome, and then successively excavate the first - Nth surrounding area of the dome and its reserved protective layer, and gradually excavate in layers from the center to the periphery along the spherical curved surface of the dome. The excavation span of the dome gradually increases, and the deformation gradually increases with the increase of the span, which is beneficial to the stability of the large-span dome and ensures the safety of dome construction.

[0007] For the excavation of the reserved protective layer in the area around the dome, drill holes from the center to the periphery along the spherical surface of the dome. The inclination angle, depth, and spacing of the drill holes in each cycle are the same, which is conducive to controlling the drilling accuracy and improving the excavation quality.

[0008] For the excavation of the reserved protective layer in the area around the dome, smooth blasting is adopted. Radial smooth blasting holes are drilled from the center to the periphery along the dome. According to the diameter of the dome sphere, determine the depth of the smooth blasting holes. The bottom spacing of the smooth blasting holes is not greater than 60 cm, and the hole mouth spacing of the smooth blasting holes is calculated inversely according to the depth of the smooth blasting holes.

[0009] The excavation method for a large-span spherical dome includes the following steps:

[0010] ⑴ Excavation of the horizontal pilot tunnel and the middle vertical pilot tunnel

[0011] Utilize the existing construction access tunnel to enter the spherical dome area, and continue to excavate the horizontal pilot tunnel 1 and the middle vertical pilot tunnel 2 forward. For the excavation of the middle vertical pilot tunnel, a three-boom rock drill is used to drill vertical holes, 2# rock emulsion explosive is manually loaded, and electronic digital detonators are used for initiation. A side-tipping loader loads the stone slag onto a dump truck, and the dump truck transports the stone slag to the slag yard.

[0012] ⑵ Support for the top arch in the middle of the dome

[0013] After the excavation of the middle vertical pilot tunnel is completed, immediately carry out the construction of the roof bolts 3 and the shotcrete layer 4 in the middle of the dome. For the roof bolts, a three-boom rock drill is used to drill holes. A forced mortar mixer strictly mixes on-site according to the mix ratio. First, inject mortar and then install the bolts. Manual labor cooperates with the three-boom rock drill to install the bolts. The mixture of shotcrete is centrally mixed in a mixing plant, transported to the construction site by a mixer, and the wet shotcreting machine is used to spray the concrete.

[0014] ⑶ Main body excavation in the area around the dome

[0015] After the support of the middle vertical pilot tunnel 2 is completed, sequentially excavate the 1-N areas around the dome and their 1-N reserved protective layers. When excavating the area 5 around the dome, adopt the layered excavation method for the 1-N reserved protective layers. The thickness of the reserved protective layer is 1.8 - 2 m. Sequentially excavate the 1-N areas around the dome. For the excavation, a three-boom rock drill is used to drill horizontal holes. When it is impossible to use a three-boom rock drill to drill holes due to limited space, a hand-held rock drill can also be used for blasting holes. 2# rock emulsion explosive is manually loaded, and electronic digital detonators are used for initiation. After blasting, a side-tipping loader loads the stone slag onto a dump truck, and the dump truck transports the stone slag to the slag yard.

[0016] ⑷ Excavation of the reserved protective layer in the area around the dome

[0017] After the main excavation of the area around the dome 5, the first to Nth reserved protective layers near the spherical surface around the dome are excavated. Smooth blasting is used for the excavation of the first to Nth reserved protective layers on the spherical surface around the dome. Radial smooth blasting holes are drilled from the center to the periphery along the spherical surface of the dome using a hand-held drill 12. The bottom spacing of the smooth blasting holes 13 is controlled not to be greater than 60 cm, and the hole mouth spacing of the smooth blasting holes 13 is calculated inversely based on the bottom spacing. Manually tie the 2# rock emulsion explosive at intervals together with detonating cords on bamboo slices, and initiate the explosion with electronic digital detonators. After excavating one layer of the reserved protective layer, manually or using a backhoe to scrape the rock slag to the bottom of the central vertical adit, and a side-tipping loader loads the rock slag into a dump truck, which transports the rock slag to the slag yard.

[0018] ⑸ Support for the area around the dome

[0019] According to the geological conditions revealed by the excavation, timely use support structures such as anchor bolts 3 and shotcrete 4 to support the excavated spherical surface of the dome. Drill holes using a three-boom rock drill jumbo, and strictly mix the mortar on-site according to the mix ratio using a forced mortar mixer. First inject the mortar and then install the anchor bolts, and manually cooperate with the three-boom rock drill jumbo to install the anchor bolts. The mixture of shotcrete is centrally mixed in a mixing plant, transported to the construction site by a mixer, and the shotcrete is sprayed using a wet shotcreting machine.

[0020] The advantages of the present invention are as follows:

[0021] After the excavation of the central vertical adit 2 is completed, timely support the crown part of the dome, and then sequentially excavate the first to Nth areas around the dome and their reserved protective layers. Gradually excavate in layers from the center to the periphery along the spherical surface of the dome. The excavation span of the dome gradually increases, and the deformation gradually increases with the increase of the span, which is beneficial to the stability of the large-span dome and ensures the construction safety of the dome.

[0022] For the excavation of the reserved protective layer in the area around the dome, drill holes from the center to the periphery along the spherical surface of the dome. The inclination angle, depth, and spacing of the drilled holes in each cycle are the same, which is beneficial to controlling the drilling accuracy and can improve the excavation quality. Brief description of the drawings

[0023] Figure 1 It is a drawing of the excavation procedure for a large-span spherical dome.

[0024] Figure 2 It is a schematic plan view of the excavation drilling for a large-span spherical dome.

[0025] Figure 3 It is a schematic diagram of the excavation drilling for a large-span spherical dome. Detailed implementation manners

[0026] Large-span spherical dome excavation method. Enter the spherical dome area through the existing construction access tunnel, and continue to excavate the horizontal pilot tunnel 1 forward. At the end of the horizontal pilot tunnel, that is, on the central axis of the spherical dome, excavate the middle vertical pilot tunnel 2 upward. Immediately after the middle vertical pilot tunnel is excavated to the spherical dome, construct the dome middle crown bolts 3 and the shotcrete layer 4. Then excavate the surrounding area of the dome. When excavating, use the method of leaving a protective layer and excavating the surrounding area of the dome in layers. First, excavate the first surrounding area of the dome 6 to form a spherical surface, and then excavate the first reserved protective layer 9 near the spherical surface. When excavating the first reserved protective layer near the spherical surface of the dome, drill holes obliquely from the center to the periphery along the dome annular surface, charge and blast, and after excavating the first reserved protective layer, rake the rock slag to the bottom of the middle vertical pilot tunnel, and transport the rock slag to the slag yard by truck. According to the geological conditions revealed by the excavation, timely use bolts and shotcrete layers to support the spherical surface of the dome that has been excavated. Then repeat the above steps to successively carry out the excavation and support of the second and third surrounding areas of the dome and their second and third reserved protective layers until all the excavation and support are completed.

[0027] After the excavation of the middle vertical pilot tunnel 2 is completed, timely support the crown part of the dome, and then successively excavate the first to third surrounding areas of the dome and their reserved protective layers, and gradually excavate from the center to the periphery in layers along the spherical surface of the dome. The excavation span of the dome gradually increases, and the deformation gradually increases with the increase of the span, which is beneficial to the stability of the large-span dome and ensures the construction safety of the dome.

[0028] For the excavation of the reserved protective layer in the surrounding area of the dome, drill holes from the center to the periphery along the spherical surface of the dome. The inclination angle, depth, and spacing of the drill holes in each cycle are the same, which is beneficial to controlling the drilling accuracy and can improve the excavation quality.

[0029] For the excavation of the reserved protective layer in the surrounding area of the dome, smooth blasting is adopted. Drill radial smooth blasting holes from the center to the periphery along the dome. According to the diameter of the dome ball, determine the depth of the smooth blasting holes. The bottom spacing of the smooth blasting holes is not greater than 60 cm, and the hole mouth spacing of the smooth blasting holes is calculated inversely according to the depth of the smooth blasting holes.

[0030] The large-span spherical dome excavation method is as follows:

[0031] ⑴ Excavation of the horizontal pilot tunnel and the middle vertical pilot tunnel

[0032] Enter the spherical dome area through the existing construction access tunnel, and continue to excavate the horizontal pilot tunnel 1 and the middle vertical pilot tunnel 2 forward. To reduce the erection of the operation platform and reduce the construction safety risk, for the excavation of the middle vertical pilot tunnel, preferably use a three-boom rock drill to drill vertical holes, manually load 2# rock emulsion explosive, initiate with electronic digital detonators, use a side-tipping loader to load the rock slag into a dump truck, and transport the rock slag to the slag yard by the dump truck.

[0033] ⑵ Support of the dome middle crown

[0034] After the excavation of the central vertical pilot tunnel is completed, the construction of the arch bolts 3 and shotcrete 4 in the middle of the dome is carried out immediately. The arch bolts are drilled by a three-boom rock drill jumbo. The forced mortar mixer mixes the mortar on-site strictly according to the mix ratio. First, the mortar is injected and then the bolts are installed. The bolts are installed manually with the cooperation of the three-boom rock drill jumbo. The mixture of shotcrete is centrally mixed by a mixing plant, and the mixer is transported to the construction site. The wet shotcreting machine is used to spray the shotcrete.

[0035] ⑶ Excavation of the main body in the surrounding area of the dome

[0036] After the support of the central vertical pilot tunnel 2 is completed, the surrounding area 5 of the dome is excavated. The first - 3 reserved protective layer layered excavation method is adopted during excavation. The thickness of the reserved protective layer is about 2m. First, the first - 3 surrounding areas 6, 7, 8 of the dome are excavated. The excavation can use a three-boom rock drill jumbo to drill horizontal holes. When it is impossible to use a three-boom rock drill jumbo to drill holes due to small space, hand-held pneumatic drills can also be used for blasting holes. 2# rock emulsion explosive is manually loaded and detonated by electronic digital detonators. After blasting, a side-dumping loader loads the stone slag into a dump truck, and the dump truck transports the stone slag to the slag yard.

[0037] ⑷ Excavation of the protective layer in the surrounding area of the dome

[0038] After the main excavation of the surrounding area 5 of the dome, the first - 3 reserved protective layers 9, 10, 11 near the spherical surface of the surrounding area of the dome are excavated. The excavation of the first - 3 reserved protective layers 9, 10, 11 of the spherical surface in the surrounding area of the dome is the key to ensuring the forming quality of the dome. Smooth blasting is adopted. Along the spherical surface of the dome, from the center to the periphery, hand-held pneumatic drills 12 are used to drill blasting holes. The bottom spacing of the smooth blasting holes 13 is controlled not to be greater than 60cm. The mouth spacing of the smooth blasting holes 13 is calculated inversely according to the bottom spacing. 2# rock emulsion explosive is manually tied to bamboo strips at intervals together with detonating cords and detonated by electronic digital detonators. After one layer is excavated, the stone slag is manually or by a backhoe raked to the bottom of the central vertical pilot tunnel. A side-dumping loader loads the stone slag into a dump truck, and the dump truck transports the stone slag to the slag yard.

[0039] ⑸ Support for the surrounding area of the dome

[0040] According to the geological conditions revealed by the excavation, the support structure such as bolts 3 and shotcrete 4 is used in a timely manner to support the spherical surface of the dome that has been excavated. The bolts are drilled by a three-boom rock drill jumbo. The forced mortar mixer mixes the mortar on-site strictly according to the mix ratio. First, the mortar is injected and then the bolts are installed. The bolts are installed manually with the cooperation of the three-boom rock drill jumbo. The mixture of shotcrete is centrally mixed by a mixing plant, and the mixer is transported to the construction site. The wet shotcreting machine is used to spray the shotcrete.

Claims

1. Method for excavating large-span spherical dome, characterized in that Enter the spherical dome area through the existing construction access adit, and continue to excavate the horizontal pilot tunnel (1) forward. At the end of the horizontal pilot tunnel, that is, along the central axis of the spherical dome, excavate the middle vertical pilot tunnel (2). After the middle vertical pilot tunnel is excavated to the spherical dome, immediately construct the dome middle crown bolts (3) and shotcrete layer (4). Then, excavate the surrounding area of the dome. When excavating, use the method of leaving a protective layer and excavating the surrounding area of the dome in layers. First, excavate the first surrounding area of the dome (6) to form a spherical surface, and then excavate the first reserved protective layer (9) near the spherical surface. When excavating the first reserved protective layer near the spherical surface of the dome, drill holes inclined from the center to the periphery along the circular surface of the dome, load explosives, and blast. After the first reserved protective layer is excavated, rake the stone slag to the bottom of the middle vertical pilot tunnel. According to the geological conditions revealed by the excavation, timely use bolts and shotcrete layer to support the excavated spherical surface of the dome. Then, repeat the above steps to excavate and support the surrounding area of the lower dome and its reserved protective layer until all excavation and support are completed.

2. The large-span spherical dome excavation method according to claim 1, characterized in that After the excavation of the middle vertical pilot tunnel (2) is completed, timely support the crown part of the dome. Then, sequentially excavate the surrounding areas of the first to Nth domes and their reserved protective layers, and gradually excavate from the center to the periphery in layers along the spherical surface of the dome. The excavation span of the dome gradually increases, and the deformation gradually increases with the increase of the span.

3. The large-span spherical dome excavation method according to claim 1, characterized in that For the excavation of the reserved protective layer in the surrounding area of the dome, drill holes from the center to the periphery along the spherical surface of the dome. The inclination angle, depth, and spacing of the drill holes in each cycle are the same.

4. The large-span spherical dome excavation method according to claim 1, characterized in that, For the excavation of the reserved protective layer in the surrounding area of the dome, smooth blasting is adopted. Drill radial smooth blasting holes from the center to the periphery along the dome. According to the diameter of the dome sphere, determine the depth of the smooth blasting holes. The bottom spacing of the smooth blasting holes is not greater than 60 cm, and the hole mouth spacing of the smooth blasting holes is calculated inversely according to the depth of the smooth blasting holes.

5. Excavation method for large-span spherical dome, including the following steps: ⑴ Excavation of horizontal pilot tunnel and middle vertical pilot tunnel Enter the spherical dome area through the existing construction access adit, and continue to excavate the horizontal pilot tunnel (1) and middle vertical pilot tunnel (2) forward. For the excavation of the middle vertical pilot tunnel, use a three-boom rock drilling jumbo to drill vertical holes, manually load 2# rock emulsion explosive, and initiate with electronic digital detonators. Use a side-tipping loader to load the stone slag into a dump truck, and the dump truck transports the stone slag to the slag yard. ⑵ Support for the middle crown of the dome After the excavation of the middle vertical pilot tunnel is completed, immediately construct the dome middle crown bolts (3) and shotcrete layer (4). For the crown bolts, use a three-boom rock drilling jumbo to drill holes, and use a forced mortar mixer to mix the mortar strictly according to the mix ratio on-site. First, inject the mortar and then install the bolts. Manually cooperate with the three-boom rock drilling jumbo to install the bolts. The mixture of shotcrete is centrally mixed in a mixing plant, transported to the construction site by a mixer, and the wet shotcreting jumbo is used to spray the shotcrete. ⑶ Main excavation of the surrounding area of the dome After the support of the central vertical pilot tunnel (2) is completed, the areas around the 1st - N domes and their 1st - N reserved protective layers are excavated in sequence. When excavating the areas around the domes, the 1st - N reserved protective layer layered excavation method is adopted, and the thickness of the reserved protective layer is 1.8 - 2 m. The areas around the 1st - N domes are excavated in sequence. For excavation, a three - boom rock drill is used to drill horizontal holes. When the space is too small to use a three - boom rock drill for drilling, a hand - held pneumatic drill is used for blast holes. 2# rock emulsion explosive is loaded manually and detonated by electronic digital detonators. After blasting, a side - tipping loader loads the stone slag into a dump truck, and the dump truck transports the stone slag to the slag yard. ⑷ Excavation of the reserved protective layer around the dome After the main body of the area around the dome is excavated, the 1st - N reserved protective layers near the spherical surface of the area around the dome are excavated. Smooth blasting is adopted for the excavation of the 1st - N reserved protective layers on the spherical surface of the area around the dome. Along the spherical surface of the dome from the center to the periphery, a hand - held pneumatic drill (12) is used to drill radial smooth - blasting holes. The bottom - hole spacing of the smooth - blasting holes (13) is controlled not to be greater than 60 cm, and the mouth - hole spacing of the smooth - blasting holes is calculated inversely according to the bottom - hole spacing. 2# rock emulsion explosive is tied to bamboo strips at intervals together with detonating cords manually and detonated by electronic digital detonators. After one layer of the reserved protective layer is excavated, the stone slag is raked to the bottom of the central vertical pilot tunnel manually or by a backhoe, and a side - tipping loader loads the stone slag into a dump truck, and the dump truck transports the stone slag to the slag yard. ⑸ Support of the area around the dome According to the geological conditions revealed by the excavation, the support structure of anchor bolts (3) and shotcrete layer (4) is used to support the spherical surface of the dome that has been excavated. A three - boom rock drill is used for drilling. A forced - type mortar mixer mixes the mortar on - site strictly according to the mix ratio. First, the mortar is injected and then the anchor bolts are installed. Manual labor is used to cooperate with the three - boom rock drill to install the anchor bolts. The mixture of shotcrete is centrally mixed in a mixing plant, transported to the construction site by a mixer, and the shotcrete is sprayed by a wet - shotcreting vehicle.

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