A long and large tunnel inclined shaft to large package method of roof picking construction method

Abstract

The application belongs to the technical field of tunnel construction, and particularly relates to a long and large tunnel inclined shaft to vertical hole large package method roof picking construction method, which realizes the standardized construction of upper and lower steps through the key steps of construction preparation and geological prediction, section expansion and step excavation, controlled blasting and mechanical excavation, locking and temporary reinforcement, vertical hole bidirectional excavation and the like, and adopts the rectangular pilot hole method construction for the poor surrounding rock and high risk section, and finally realizes the standardized construction of upper and lower steps, including inclined shaft lining reinforcement, full-width rectangular pilot hole transverse cutting, temporary shed support system construction and support after support removal and the like processes. The key innovation point lies in that the construction process is optimized, the organic combination of temporary support and permanent support is realized, the material consumption and construction cost are significantly reduced, and the smooth tunnel contour is ensured through the accurate overbreak and underbreak control.

Description

Technical Field

[0001] This invention belongs to the field of tunnel construction technology, specifically relating to a method for constructing a long tunnel by using a large-scale roof-lifting method when the inclined shaft turns into the main tunnel. Background Technology

[0002] In the construction of long tunnels, inclined shafts are key structures for auxiliary construction, ventilation, and schedule control. The transition from the inclined shaft to the main tunnel requires a roof-lifting operation, which is characterized by a large open face, strong disturbance to the surrounding rock, complex stress system, and high safety risks.

[0003] The existing traditional overburden excavation process generally suffers from the following technical defects: 1. Long exposure time of surrounding rock, high dependence on self-stabilization capacity, easy to fall rocks and collapse, resulting in prominent safety risks; 2. Small working space, making it difficult to deploy large machinery, resulting in low construction efficiency and long construction period; 3. Poor blasting control precision, serious over-excavation and under-excavation, and poor contour forming quality; 4. Untimely closure of initial support, unreasonable stress on the support structure, and easy subsidence and instability of the arch frame; 5. Disconnection between temporary support and permanent support, resulting in large material consumption, high cost, and complicated procedures. Summary of the Invention

[0004] In order to solve at least one of the above-mentioned technical problems in the prior art, the present invention provides a method for constructing a long tunnel by using a large-scale roof-lifting method for converting an inclined shaft into a main tunnel.

[0005] This invention is achieved using the following technical solution: a method for constructing a long tunnel from an inclined shaft to a main tunnel using a large-scale roof-lifting technique, comprising: Before construction, the construction site was explored using advanced geological forecasting, and monitoring points were set up and settlement was reserved. A reinforcing ring and a beam-column support platform are installed at a safe distance from the design line of the main tunnel at the end of the inclined shaft. For different surrounding rock grades, either the transitional pilot tunnel method or the rectangular pilot tunnel method is used for roof lifting construction; among them... For sections with surrounding rock grades I to IV, the transition tunnel method is used for construction. In the inclined shaft section, the cross-section is gradually enlarged and the steps are excavated to the design outline. By controlling blasting and mechanical excavation, a transition excavation face that exceeds the outline of the main tunnel is formed, and temporary reinforcement such as locking toe, lateral support and locking joint reinforcement is carried out immediately. For sections with surrounding rock grades V or VI, the rectangular pilot tunnel method is used for construction. The lining of the inclined shaft entering the main tunnel area is strengthened. The inclined shaft is horizontally cut into the arch of the main tunnel to form an arc-shaped top. I-beam scaffolding is erected to form a temporary scaffolding support system. After the upper pilot tunnel is stable, the principle of removing the support first and then supporting is followed to form a closed support structure in a timely manner. After entering the main tunnel, standardized construction of the upper and lower steps is implemented. The upper step is required to be supported in a timely manner and the locking foot is strengthened, while the lower step is to be excavated in a staggered manner and the arch foot is to be reinforced. Throughout the entire construction process, construction quality, safety, and environmental protection are monitored.

[0006] Preferably, prior to construction, the construction site is surveyed using advanced geological forecasting methods, and monitoring points are set up with allowances for settlement, including: Advanced geological prediction was carried out using TSP, ground-penetrating radar, and advanced horizontal drilling. Every three excavation cycles, a 5-meter-long drill rod is used for advance detection to accurately determine the grade of the surrounding rock and the hydrological conditions ahead. Monitoring and measurement points were set up along the excavation route at a spacing of 3 meters. A 15-centimeter deformation and settlement space was reserved in advance at the intersection of the inclined shaft and the main tunnel to provide safety redundancy for subsequent construction and to dynamically adjust the support parameters accordingly.

[0007] Preferably, a reinforcing ring and a beam-column support platform are installed at a safe distance from the design line of the main tunnel at the end of the inclined shaft, including: At the end of the inclined shaft where it is about to enter the main tunnel, a reinforcing ring made of double I20a steel is pre-constructed 15 centimeters from the inner edge of the maximum span of the secondary lining of the main tunnel. A longitudinal horizontal support beam and column are installed above the reinforcing ring, which together form a stable and reliable platform for construction operations. The bottom of the column is supported by 32b channel steel and precast reinforced concrete pads with dimensions of 50 cm × 50 cm × 50 cm to prevent uneven settlement caused by concentrated stress and to ensure the safety and stability of the intersection structure during the cantilever construction.

[0008] Preferably, in the construction of the transition pilot tunnel method, In the transition area from the inclined shaft section to the main tunnel, the step method is used to gradually expand the excavation upward and outward from the cross-section of the inclined shaft until a transition excavation surface is formed whose height and longitudinal length both exceed the final design outline of the main tunnel. The excavation was carried out by combining small blasting with excavators, and the resulting pilot tunnel was between 8.34 meters and 11.72 meters wide, strictly adhering to the process principles of short advances and weak blasting. At the arch foot of the excavation outline, Φ42 grouting pipes with a length of 3.5 meters are laid out for foot locking, with 4 pipes per arch frame. At the same time, I14 I-beams are added between arch frames No. 10 to No. 26 as lateral supports, with a spacing of 2.4 meters to 4.8 meters. At the key locking position at the entrance to the main tunnel, I20 double-splitting I-beams are used and 26 cm thick C25 concrete is sprayed for reinforcement.

[0009] Preferably, in the rectangular pilot tunnel method of construction, The inclined shaft structure within 10 meters outward from the inner edge of the maximum span of the secondary lining of the main tunnel shall be pre-strengthened according to the lining standard one level higher than that of the design. Using the full cross-sectional width of the existing inclined shaft, the tunnel is excavated laterally and vertically into the arch area of ​​the main tunnel. Through continuous arc-shaped roof lifting operations, the arch elevation of the pilot tunnel is gradually raised to the design elevation of the main tunnel. The arch elevation of the pilot tunnel is slightly higher than the final design outline of the main tunnel, leaving sufficient space for subsequent surrounding rock deformation and initial support thickness. A canopy-type support system with I14 I-beams as the main components is erected along the tunnel excavation direction. The support spacing is 1.5 meters, and the supports are connected in a ring with φ22 threaded steel bars to form a whole. At the same time, the key transverse components in this temporary support system are incorporated into the permanent support design to achieve the integration of temporary support and permanent structure.

[0010] Preferably, after entering the main tunnel, standardized construction of upper and lower steps is implemented, including: After each cycle of excavation on the upper step, initial support is immediately implemented, and the spacing of the anchor pipes is increased to 2 meters to enhance the overall stability of the arch frame. When excavating the lower step, the left and right sides should be staggered. The excavation length on each side should not exceed the spacing of two arch frames. The staggered distance between the front and back working faces on the left and right sides should be maintained at 3 to 5 meters or more. 32b channel steel is placed under the arch foot of each arch frame to increase the load-bearing area. When encountering particularly weak geological conditions, C30 concrete strip beams are further constructed to prevent the arch frame from settling and deforming due to insufficient load-bearing capacity.

[0011] Preferably, throughout the entire construction process, construction quality, safety, and environmental protection are monitored, including: The tunnel excavation outline is precisely measured and controlled in three dimensions using a total station to ensure that over-excavation and under-excavation strictly meet the design and construction specifications. High-strength bolts are used for all connections between steel arch frames. The weld length of any necessary on-site welded connections should not be less than 10 times the diameter of the welded steel bar. When carrying out blasting operations, the safety distance must not be less than 200 meters, and sufficient emergency rescue materials must be stored in the tunnel, while ensuring that duty vehicles are on standby at all times. Construction wastewater is treated in multi-stage sedimentation tanks to meet standards before being discharged. All waste is transported to designated compliant waste disposal sites and low-noise, low-emission machinery and equipment are given priority for construction operations.

[0012] Compared with the prior art, the beneficial effects of the present invention are: This invention provides a method for constructing the main tunnel from an inclined shaft in a long tunnel using a large-scale roof-lifting technique. This method involves key steps such as construction preparation and geological prediction, cross-section enlargement and bench excavation, controlled blasting and mechanical excavation, locking and temporary reinforcement, and bidirectional excavation of the main tunnel. For sections with poor surrounding rock and high risk, a rectangular pilot tunnel method is employed, including inclined shaft lining reinforcement, transverse entry into a full-width rectangular pilot tunnel, construction of a temporary scaffolding support system, and pre-removal of supports followed by reinforcement. This ultimately achieves standardized construction of the upper and lower benches. Its key innovation lies in optimizing the construction process, achieving an organic combination of temporary and permanent support, significantly reducing material consumption and construction costs. Simultaneously, through precise control of over- and under-excavation, it ensures a smooth tunnel outline, without encroachment or sags, effectively improving construction quality and safety. This provides an efficient, economical, and reliable technical solution for the construction of long tunnels from inclined shafts to main tunnels. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of the process for a method of constructing a long tunnel from an inclined shaft to a main tunnel using the large-package method of roof support, provided by the present invention. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] It should be noted that the structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationships, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should fall within the scope of the technical content disclosed in the present invention. It should be noted that in this specification, relational terms such as "first" and "second" are only used to distinguish one entity from several other entities, and do not necessarily require or imply any actual relationship or order between these entities.

[0017] This invention provides an embodiment: such as Figure 1 As shown, this invention provides a method for constructing a long tunnel from an inclined shaft to a main tunnel using a large-scale roof-lifting construction method, comprising: S110: Before construction, the construction site will be explored using advanced geological forecasting methods, and monitoring points will be set up and settlement allowances will be reserved.

[0018] In an embodiment of the present invention, TSP, ground-penetrating radar and advanced horizontal drilling are used for advanced geological prediction. Every three excavation cycles, a 5-meter-long drill rod is used for advance detection to accurately determine the grade of the surrounding rock and the hydrological conditions ahead. Monitoring and measurement points were set up along the excavation route at a spacing of 3 meters. A 15-centimeter deformation and settlement space was reserved in advance at the intersection of the inclined shaft and the main tunnel to provide safety redundancy for subsequent construction and to dynamically adjust the support parameters accordingly.

[0019] S120: A reinforcing ring and a beam-column support platform are installed at a safe distance from the design line of the main tunnel at the end of the inclined shaft.

[0020] At the end of the inclined shaft where it is about to enter the main tunnel, a reinforcing ring made of double I20a steel is pre-constructed 15 centimeters from the inner edge of the maximum span of the secondary lining of the main tunnel. A longitudinal horizontal support beam and column are installed above the reinforcing ring, which together form a stable and reliable platform for construction operations. The bottom of the column is supported by 32b channel steel and precast reinforced concrete pads with dimensions of 50 cm × 50 cm × 50 cm to prevent uneven settlement caused by concentrated stress and to ensure the safety and stability of the intersection structure during the cantilever construction.

[0021] S130: For different surrounding rock grades, either the transitional pilot tunnel method or the rectangular pilot tunnel method is used for roof lifting construction; among which... For sections with surrounding rock grades I to IV, the transition tunnel method is used for construction. In the inclined shaft section, the cross-section is gradually enlarged and the steps are excavated to the design outline. By controlling blasting and mechanical excavation, a transition excavation face that exceeds the outline of the main tunnel is formed, and temporary reinforcement such as locking toe, lateral support and locking joint reinforcement is carried out immediately. For sections with surrounding rock grades V or VI, the rectangular pilot tunnel method is used for construction. The lining of the inclined shaft entering the main tunnel area is strengthened. The inclined shaft is horizontally cut into the arch of the main tunnel to form an arc-shaped top. I-beam steel scaffolding is erected to form a temporary scaffolding support system. After the upper pilot tunnel is stable, the principle of removing the supports first and then supporting is followed to form a closed support structure in a timely manner.

[0022] Specifically, in the construction of the transition pilot tunnel method, In the transition area from the inclined shaft section to the main tunnel, the step method is used to gradually expand the excavation upward and outward from the cross-section of the inclined shaft until a transition excavation surface is formed whose height and longitudinal length both exceed the final design outline of the main tunnel. The excavation was carried out by combining small blasting with excavators, and the resulting pilot tunnel was between 8.34 meters and 11.72 meters wide, strictly adhering to the process principles of short advances and weak blasting. At the arch foot of the excavation outline, Φ42 grouting pipes with a length of 3.5 meters are laid out for foot locking, with 4 pipes per arch frame. At the same time, I14 I-beams are added between arch frames No. 10 to No. 26 as lateral supports, with a spacing of 2.4 meters to 4.8 meters. At the key locking position at the entrance to the main tunnel, I20 double-splitting I-beams are used and 26 cm thick C25 concrete is sprayed for reinforcement.

[0023] In the construction of the rectangular pilot tunnel method, The inclined shaft structure within 10 meters outward from the inner edge of the maximum span of the secondary lining of the main tunnel shall be pre-strengthened according to the lining standard one level higher than that of the design. Using the full cross-sectional width of the existing inclined shaft, the tunnel is excavated laterally and vertically into the arch area of ​​the main tunnel. Through continuous arc-shaped roof lifting operations, the arch elevation of the pilot tunnel is gradually raised to the design elevation of the main tunnel. The arch elevation of the pilot tunnel is slightly higher than the final design outline of the main tunnel, leaving sufficient space for subsequent surrounding rock deformation and initial support thickness. A canopy-type support system with I14 I-beams as the main components is erected along the tunnel excavation direction. The support spacing is 1.5 meters, and the supports are connected in a ring with φ22 threaded steel bars to form a whole. At the same time, the key transverse components in this temporary support system are incorporated into the permanent support design to achieve the integration of temporary support and permanent structure.

[0024] S140: After entering the main tunnel, standardized construction of upper and lower steps is implemented. The upper step is required to be supported in a timely manner and the footing should be reinforced. The lower step is to be excavated in a staggered manner and the arch footing should be strengthened.

[0025] After each cycle of excavation on the upper step, initial support is immediately implemented, and the spacing of the anchor pipes is increased to 2 meters to enhance the overall stability of the arch frame. When excavating the lower step, the left and right sides should be staggered. The excavation length on each side should not exceed the spacing of two arch frames. The staggered distance between the front and back working faces on the left and right sides should be maintained at 3 to 5 meters or more. 32b channel steel is placed under the arch foot of each arch frame to increase the load-bearing area. When encountering particularly weak geological conditions, C30 concrete strip beams are further constructed to prevent the arch frame from settling and deforming due to insufficient load-bearing capacity.

[0026] S150: Monitor construction quality, safety, and environmental protection throughout the entire construction process.

[0027] Specifically, a total station is used to accurately measure and control the three-dimensional coordinates of the tunnel excavation outline to ensure that the over-excavation and under-excavation amounts strictly comply with the design and construction specifications. High-strength bolts are used for all connections between steel arch frames. The weld length of any necessary on-site welded connections should not be less than 10 times the diameter of the welded steel bar. When carrying out blasting operations, the safety distance must not be less than 200 meters, and sufficient emergency rescue materials must be stored in the tunnel, while ensuring that duty vehicles are on standby at all times. Construction wastewater is treated in multi-stage sedimentation tanks to meet standards before being discharged. All waste is transported to designated compliant waste disposal sites and low-noise, low-emission machinery and equipment are given priority for construction operations.

[0028] This invention allows for flexible selection of transition tunnels or rectangular tunnels based on the surrounding rock grade, making it highly adaptable; it changes the layout from a vertical main tunnel to a parallel main tunnel, reducing exposure and over-excavation; and the crossbeams of the support frame directly serve as permanent supports, reducing replacements and shortening the construction period.

[0029] The present invention has the following advantages: 1. Significantly improved safety: The exposure time of the surrounding rock is greatly shortened, the support is sealed in time, and the risk of collapse is reduced.

[0030] 2. Quality controllable: precise control of over- and under-digging, smooth outline, no encroachment, and no hanging feet.

[0031] 3. Shortened construction period: The construction period for a single section of the cantilever roof is shortened by 15 days, and the construction efficiency is increased by more than 30%.

[0032] 4. Cost reduction: Reduce material waste and rework.

[0033] 5. Green and environmentally friendly: Reduced waste, lower energy consumption, and reduced dust and vibration, in line with green construction.

[0034] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for constructing a long tunnel from an inclined shaft to a main tunnel using a large-scale roof-lifting construction method, characterized in that... include: Before construction, the construction site was explored using advanced geological forecasting, and monitoring points were set up and settlement was reserved. A reinforcing ring and a beam-column support platform are installed at a safe distance from the design line of the main tunnel at the end of the inclined shaft. For different surrounding rock grades, either the transitional pilot tunnel method or the rectangular pilot tunnel method is used for roof lifting construction; among them... For sections with surrounding rock grades I to IV, the transition tunnel method is used for construction. In the inclined shaft section, the cross-section is gradually enlarged and the steps are excavated to above the design outline. By controlling blasting and mechanical excavation, a transition excavation face that exceeds the outline of the main tunnel is formed, and temporary reinforcement such as locking toe, lateral support and locking joint reinforcement is carried out immediately. For sections with surrounding rock grades V or VI, the rectangular pilot tunnel method is used for construction. The lining of the inclined shaft entering the main tunnel area is strengthened. The inclined shaft is horizontally cut into the arch of the main tunnel to form an arc-shaped top. I-beam steel scaffolding is erected to form a temporary scaffolding support system. After the upper pilot tunnel is stable, the principle of removing the support first and then supporting is followed to form a closed support structure in a timely manner. After entering the main tunnel, standardized construction of the upper and lower steps is implemented. The upper step is required to be supported in a timely manner and the locking foot is strengthened, while the lower step is to be excavated in a staggered manner and the arch foot is to be reinforced. Throughout the entire construction process, construction quality, safety, and environmental protection are monitored.

2. The method for constructing a long tunnel from an inclined shaft to a main tunnel using the large-scale roof-lifting method according to claim 1, characterized in that, Prior to construction, advanced geological forecasting was conducted at the construction site, and monitoring points were set up with allowances for settlement, including: Advanced geological prediction was carried out using TSP, ground-penetrating radar, and advanced horizontal drilling. Every three excavation cycles, a 5-meter-long drill rod is used for advance detection to accurately determine the grade of the surrounding rock and the hydrological conditions ahead. Monitoring and measurement points were set up along the excavation route at a spacing of 3 meters. A 15-centimeter deformation and settlement space was reserved in advance at the intersection of the inclined shaft and the main tunnel to provide safety redundancy for subsequent construction and to dynamically adjust the support parameters accordingly.

3. The method for constructing a long tunnel from an inclined shaft to a main tunnel using the large-scale roof-lifting method according to claim 1, characterized in that, A reinforcing ring and a beam-column support platform are installed at a safe distance from the design line of the main tunnel at the end of the inclined shaft, including: At the end of the inclined shaft where it is about to enter the main tunnel, a reinforcing ring made of double I20a steel is pre-constructed 15 centimeters from the inner edge of the maximum span of the secondary lining of the main tunnel. A longitudinal horizontal support beam and column are installed above the reinforcing ring, which together form a stable and reliable platform for construction operations. The bottom of the column is supported by 32b channel steel and precast reinforced concrete pads with dimensions of 50 cm × 50 cm × 50 cm to prevent uneven settlement caused by concentrated stress and to ensure the safety and stability of the intersection structure during the cantilever construction.

4. The method for constructing a long tunnel from an inclined shaft to a main tunnel using the large-scale roof-lifting method according to claim 1, characterized in that, During the construction of the aforementioned transition tunnel method In the transition area from the inclined shaft section to the main tunnel, the step method is used to gradually expand the excavation upward and outward from the cross-section of the inclined shaft until a transition excavation surface is formed whose height and longitudinal length both exceed the final design outline of the main tunnel. The excavation was carried out by combining small blasting with excavators, and the resulting pilot tunnel was between 8.34 meters and 11.72 meters wide, strictly adhering to the process principles of short advances and weak blasting. At the arch foot of the excavation outline, Φ42 grouting pipes with a length of 3.5 meters are laid out for foot locking, with 4 pipes per arch frame. At the same time, I14 I-beams are added between arch frames No. 10 to No. 26 as lateral supports, with a spacing of 2.4 meters to 4.8 meters. At the key locking position at the entrance to the main tunnel, I20 double-splitting I-beams are used and 26 cm thick C25 concrete is sprayed for reinforcement.

5. The method for constructing a long tunnel from an inclined shaft to a main tunnel using the large-scale roof-lifting method according to claim 1, characterized in that... In the construction using the rectangular pilot tunnel method... The inclined shaft structure within 10 meters outward from the inner edge of the maximum span of the secondary lining of the main tunnel shall be pre-strengthened according to the lining standard one level higher than that of the design. Using the full cross-sectional width of the existing inclined shaft, the tunnel is excavated laterally and vertically into the arch area of ​​the main tunnel. Through continuous arc-shaped roof lifting operations, the arch elevation of the pilot tunnel is gradually raised to the design elevation of the main tunnel. The arch elevation of the pilot tunnel is slightly higher than the final design outline of the main tunnel, leaving sufficient space for subsequent surrounding rock deformation and initial support thickness. A canopy-type support system with I14 I-beams as the main components is erected along the tunnel excavation direction. The support spacing is 1.5 meters, and the supports are connected in a ring with φ22 threaded steel bars to form a whole. At the same time, the key transverse components in this temporary support system are incorporated into the permanent support design to achieve the integration of temporary support and permanent structure.

6. The method for constructing a long tunnel from an inclined shaft to a main tunnel using the large-scale roof-lifting method according to claim 1, characterized in that, After entering the main tunnel, standardized construction methods for ascending and descending steps are implemented, including: After each cycle of excavation on the upper step, initial support is immediately implemented, and the spacing of the anchor pipes is increased to 2 meters to enhance the overall stability of the arch frame. When excavating the lower step, the left and right sides should be staggered. The excavation length on each side should not exceed the spacing of two arch frames. The staggered distance between the front and back working faces on the left and right sides should be maintained at 3 to 5 meters or more. 32b channel steel is placed under the arch foot of each arch frame to increase the load-bearing area. When encountering particularly weak geological conditions, C30 concrete strip beams are further constructed to prevent the arch frame from settling and deforming due to insufficient load-bearing capacity.

7. The method for constructing a long tunnel from an inclined shaft to a main tunnel using the large-scale roof-lifting method according to claim 1, characterized in that, Throughout the construction process, construction quality, safety, and environmental protection are monitored, including: The tunnel excavation outline is precisely measured and controlled in three dimensions using a total station to ensure that over-excavation and under-excavation strictly meet the design and construction specifications. High-strength bolts are used for all connections between steel arch frames. The weld length of any necessary on-site welded connections should not be less than 10 times the diameter of the welded steel bar. When carrying out blasting operations, the safety distance must not be less than 200 meters, and sufficient emergency rescue materials must be stored in the tunnel, while ensuring that duty vehicles are on standby at all times. Construction wastewater is treated in multi-stage sedimentation tanks to meet standards before being discharged. All waste is transported to designated compliant waste disposal sites and low-noise, low-emission machinery and equipment are given priority for construction operations.

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