Method for quickly constructing underground space below existing road

Abstract

A method for rapidly constructing an underground space below an existing road is characterized in that a green belt exists in the center of the existing road, and the method comprises the steps that 1, fender posts or underground diaphragm walls are driven from the ground on the outer side of the underground space structure; 2, steel pipe piles and steel pipe column foundations of the steel pipe piles are constructed in a green belt in the center of the existing road; 3, a temporary vertical shaft is constructed in the road center green belt; 4, pipe roofing working wells are constructed on the two sides of the ground; 5, the pipe roofing is arranged in the pipe roofing working well in a driving mode; 6, after the pipe roofing construction is completed, pile top beams are constructed in the pipe roofing working well, and top longitudinal beams above the middle stand columns are constructed in the temporary vertical shaft; 7, backfilling the pipe roofing working well and the temporary vertical shaft foundation pit; 8, under the protection of the combined support, construction of an underground space structure is conducted; therefore, according to the method, the road is not damaged, the ground traffic is not influenced, pipeline relocation is not needed, underground excavation of pilot tunnels is not needed, the construction speed is high, and the manufacturing cost is low.

Description

Technical Field

[0001] The present invention relates to the technical field of underground space construction, and in particular to a method for quickly constructing underground space under an existing road by a cover-and-cut method without destroying the road, affecting ground traffic, relocating municipal pipelines, or setting up a dark excavation guide tunnel. Background Art

[0002] With the vigorous development of underground spaces such as urban rail transit, pipeline corridors, and underground commercial streets, especially when the urban rail transit network is densified, it is necessary to build underground projects under existing road conditions without affecting ground traffic. Therefore, pipeline relocation and road covering are not allowed. At the same time, the construction period is fast and investment is saved.

[0003] To this end, in view of the above-mentioned defects, the designers of the present invention have conducted intensive research and design, combined with the experience and achievements of many years of engaging in related industries, and have researched and designed a method for quickly constructing underground space under existing roads to overcome the above-mentioned defects. Summary of the invention

[0004] The purpose of the present invention is to provide a method for quickly constructing an underground space under an existing road, which method does not damage the road, does not affect ground traffic, does not require pipeline relocation, has no dark digging guide tunnels, has a fast construction speed and a low cost.

[0005] To achieve the above object, the present invention discloses a method for quickly constructing an underground space under an existing road, wherein there is a green belt in the center of the existing road, and the method is characterized by comprising the following steps: Step 1: Drive retaining piles or underground continuous walls from the ground outside the underground space structure; Step 2: Construct steel pipe piles and their steel pipe column foundations in the green belt in the middle of the existing road; Step 3: Construct a temporary shaft in the central green belt of the road, construct a locking ring beam, excavate the soil and set up a steel grid. The bottom of the temporary shaft foundation pit is flush with the bottom elevation of the top longitudinal beam; Step 4: Construct pipe curtain working wells on both sides of the ground. The pipe curtain working wells are lower than the bottom elevation of the crown beam; Step 5: Install the pipe curtain in the pipe curtain working pit, and place one end of the pipe curtain in the reserved top longitudinal beam in the temporary shaft, with one end of the pipe curtain placed in the top longitudinal beam by no less than 500 mm, and fill the pipe curtain with cement mortar or fine stone concrete; Step 6: After the pipe curtain is constructed, the pile top crown beam is constructed in the pipe curtain working shaft, and the top longitudinal beam above the middle column is constructed in the temporary shaft. The concrete is poured densely, one end of the pipe curtain is restrained in the top longitudinal beam, and the other end of the pipe curtain is placed in the crown beam, and the distance inside the crown beam is not less than 500 mm; Step 7: Backfill the pipe curtain working pit and temporary shaft foundation pit; Step 8: Under the protection of the combined support consisting of pipe curtains, retaining piles or underground continuous walls, cap beams and top longitudinal beams, the underground space structure is constructed.

[0006] Among them: It also includes step 9: After the construction of the underground space structure is completed, the pipe curtain working shaft and temporary shaft 3.0 m below the ground are dismantled, and the underground space auxiliary structure is constructed according to the needs of the underground space.

[0007] Among them: the construction of the underground space structure in step 8 is specifically as follows: when the earth is excavated downward to 500mm below the first internal support, the first internal support is constructed; when the earth is continued to be excavated downward to 500mm below the second internal support, the second internal support is constructed; when the remaining soil is excavated to the bottom elevation of the bottom plate, the bottom plate is constructed, the side wall of the second underground floor is constructed, the middle plate is constructed, the side wall of the first underground floor is constructed, and the top plate is constructed.

[0008] Among them: when the span of the underground space is large and the rigidity of the pipe curtain is insufficient, steel bars or steel strands are inserted into the steel pipes of the pipe curtain, and the steel bars or steel strands are anchored into the top crown beams of the retaining piles or underground continuous wall piles and the top longitudinal beams of the central columns to increase the overall rigidity of the pipe curtain.

[0009] Among them: the diameter of the pipe curtain is 108 mm ~ 1000 mm.

[0010] Wherein: the pipe curtain comprises a plurality of fixedly connected steel pipes, a female lock buckle is provided at one end of the pipe curtain, and a male lock buckle which can be buckled and locked with the female lock buckle is provided at the other end, so that a plurality of pipe curtains can achieve different requirements through the matching lock buckles of the male lock buckle and the female lock buckle.

[0011] Wherein: in step 6, through the pile top crown beam and the top longitudinal beam, the two ends of the pipe curtain are respectively constrained in the top longitudinal beam and the crown beam to form a combined support system; The specific construction method is: Pre-drilling construction: Before the pipe curtain is installed, pre-drilling construction is carried out. According to the designed position and diameter of the pipe curtain, a geological drill is used to drill a pilot hole. The role of the pilot hole is to provide precise guidance for the installation of the pipe curtain and reduce the deviation of the pipe curtain during the installation process. During the drilling of the pilot hole, measuring equipment such as a total station and a gyroscope are also used for real-time monitoring to ensure the accuracy of the pilot hole. After the pilot hole is completed, the pipe curtain is installed in the pilot hole by jacking or drilling, which effectively improves the accuracy of the pipe curtain construction; Segmented construction and measurement review: The pipe curtain construction is divided into several sections. After each section is completed, a comprehensive measurement review is carried out. At the joints of each section of the pipe curtain, high-precision measuring instruments are used to measure the docking deviation of the pipe curtain, including axial deviation and radial deviation.

[0012] Wherein: Step 2 also includes: Preparation before construction: Accurate measurement and layout: Use a high-precision total station to conduct a comprehensive measurement of the construction site, accurately mark the position and axis of the steel pipe piles according to the design drawings, set obvious control points and control lines, and conduct multiple reviews to ensure the accuracy of the layout; Construction process control: Setting up guiding devices: Setting up guiding fixtures on the top of the steel pipe pile and the pile frame to guide the steel pipe pile in real time during the piling process to prevent it from deflecting and tilting during the driving process; Real-time monitoring: Use a total station to conduct real-time monitoring during the piling process, measure the verticality and position deviation of the steel pipe piles at regular intervals, and make adjustments immediately if the deviation exceeds the allowable range; Post-construction inspection: Pile testing: After the piling is completed, ultrasonic testing, core drilling and other methods are used to conduct a comprehensive test on the verticality and position accuracy of the steel pipe piles. For piles that do not meet the requirements, remedial measures are taken in a timely manner, such as correcting the deviation or adding piles.

[0013] Wherein: in step 3, layered and segmented excavation is adopted, and the specific excavation steps are as follows: First layer excavation: starting from the wellhead, excavate the middle part of the shaft first according to the layer thickness required by the design, and then gradually expand to the periphery to form a pot bottom shape; Erection of support: After the first layer of excavation is completed, steel support or shotcrete wall is installed on the shaft wall to reinforce the shaft wall and prevent the shaft wall from collapsing; Excavation of the second layer and below: Repeat the excavation and support operations of the first layer until the excavation reaches the designed depth.

[0014] Wherein: in step 5, high-performance cement is used as the cementitious material for the filling material, and quartz sand is selected as the fine aggregate, and an appropriate amount of water reducing agent and expansion agent are added to the filling material; The pouring process adopts high-pressure rotary jet grouting technology: During the pipe curtain filling process, high-pressure rotary jet grouting technology is adopted, and the pouring is carried out in sections and layers: According to the length and diameter of the pipe curtain, the pipe curtain is divided into several sections, and the filling is carried out by section and layer pouring method.

[0015] From the above content, it can be seen that the method of the present invention for quickly constructing underground space under an existing road has the following effects: 1. When there is a green belt in the center of an existing road or conditions are met for constructing a temporary vertical shaft in the center and conditions are met for constructing a pipe curtain working shaft on both sides of the existing road, retaining piles or underground continuous walls and pipe curtain support systems can be formed. There is no need to relocate pipelines or break up roads, and underground space structures can be directly constructed.

[0016] 2. Underground space structure construction is carried out under the support of retaining piles or underground continuous walls and pipe curtains, and permanent steel pipe columns and their steel pipe column foundations are constructed in the central green belt of the road or in the center, which can form an arch structure with good force resistance. The underground space structure can be constructed without setting up a dark excavation guide tunnel.

[0017] 3. Compared with underground excavation construction, this method does not require underground excavation of pilot tunnels. The construction speed is significantly accelerated and the cost is greatly reduced.

[0018] The details of the present invention can be obtained from the following description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram showing a method of the present invention for rapidly constructing an underground space under an existing road.

[0020] Figure 2 A schematic diagram of the pipe-roof connection structure of the present invention is shown.

[0021] Reference numerals: 1. Ground, 2. Pipe curtain working shaft, 3. Locking ring beam, 4. Pipe curtain, 5. Crown beam, 6. Guarding piles, 7. Underground space structure, 8. Underground pipelines, 9. Top plate, 10. Underground first floor side wall, 11. Middle plate, 12. Underground second floor side wall, 13. Bottom plate, 14. Top longitudinal beam, 15. Steel pipe piles, 16. Middle longitudinal beam, 17. Bottom longitudinal beam, 18. Steel pipe column foundation, 19. Temporary shaft, 20. Retaining wall, 21. First inner support, 22. Second inner support, 40. Steel pipe, 41. Female lock buckle, 42. Male lock buckle. DETAILED DESCRIPTION

[0022] See also Figure 1 and 2 , showing the method of the present invention for quickly constructing an underground space under an existing road, wherein there is a green belt in the center of the existing road or conditions for constructing a pile foundation are available in the center.

[0023] The method package for quickly constructing an underground space under an existing road may include the following steps: Step 1: On the outside of the underground space structure 7, which is a columnar space structure, retaining piles 6 or underground continuous walls are driven from the ground 1. The net distance between the retaining piles 6 or the underground continuous wall and the underground space structure 7 is preferably 100 mm. Depending on the construction machinery and construction technology level, the gap between the retaining piles and the structure can be appropriately increased to prevent the retaining piles from invading the underground space structure 7 after the foundation pit is excavated.

[0024] Step 2: construct steel pipe piles 15 and their steel pipe column foundations 18 in the green belt in the middle of the existing road, wherein the steel pipe piles 15 and their steel pipe column foundations 18 form permanent columns and pile foundations of the underground space structure 7, which are located in the middle of the underground space structure.

[0025] Step 3: construct a temporary shaft 19 in the central green belt of the road, construct a locking ring beam 3, excavate the soil and set up a steel grid, and the bottom of the temporary shaft 19 foundation pit is flush with the bottom elevation of the top longitudinal beam 14.

[0026] Step 4: Construct pipe curtain working wells 2 on both sides of the ground 1. The pipe curtain working wells 2 are lower than the bottom elevation of the crown beam 5. Optionally, the bottom of the shallow foundation pit in the open space on both sides of the road is not less than 0.5m below the pipe curtain construction distance, which should meet the pipe shed construction space.

[0027] Step 5: Install the pipe curtain 4 in the pipe curtain working shaft 2, and place one end of the pipe curtain in the reserved top longitudinal beam in the temporary shaft 19, and one end of the pipe curtain is placed in the top longitudinal beam 14 by no less than 500 mm, and fill the pipe curtain with cement mortar or fine stone concrete. The preferred diameter of the pipe curtain is 108 mm to 1000 mm. The parameters such as the pipe curtain diameter can be reasonably determined according to the underground space span, upper load and other conditions.

[0028] Step 6: After the construction of the pipe curtain 4 is completed, the pile top crown beam 5 is constructed in the pipe curtain working shaft 2, and the top longitudinal beam 14 above the middle column is constructed in the temporary shaft. The concrete is poured densely, one end of the pipe curtain is constrained in the top longitudinal beam 14, and the other end of the pipe curtain 4 is placed in the crown beam 5, and the distance inside the crown beam 5 is not less than 500 mm.

[0029] In this step, a combined support system is formed by first constructing the pile top crown beam 5 and the top longitudinal beam 14, and then constraining the two ends of the pipe curtain in the top longitudinal beam 14 and the crown beam 5 respectively. When constructing the pipe curtain in the pipe curtain working shaft 2, it is difficult to ensure the accuracy of the pipe curtain construction, and high-precision measurement and installation equipment are required. At the same time, the anchoring depth of the pipe curtain in the top longitudinal beam and the crown beam must be ensured. By forming a combined support system composed of retaining piles 6 or underground continuous walls and pipe curtains 4, the vertical load above the underground space can be directly borne, avoiding pipeline relocation and road coverage, reducing the impact of construction on the surrounding environment, and reducing construction costs and construction period.

[0030] Among them, in order to ensure high-precision measurement, the high-precision measurement equipment used is the total station and gyroscope. Before construction, the total station is used to accurately measure the coordinates of the pipe curtain working shaft and establish a high-precision measurement control network. During the installation of the pipe curtain, the position deviation of the pipe curtain is monitored in real time by the total station. The total station is set up on a stable control point to observe the measurement target at the front end of the pipe curtain. Multiple observation points are set on the measurement target to accurately measure the deviation of the pipe curtain in the horizontal and vertical directions. According to the measurement data, the angle and propulsion direction of the pipe curtain installation equipment are adjusted in time to ensure that the pipe curtain is installed according to the designed trajectory.

[0031] Moreover, by installing a high-precision gyroscope inside the pipe curtain, the gyroscope can monitor the tilt angle and azimuth changes of the pipe curtain in real time. Since the gyroscope is not interfered by external magnetic fields and other factors, the measurement accuracy is high. During the installation of the pipe curtain, the gyroscope transmits the measurement data to the ground monitoring system in real time. Once the pipe curtain is tilted or deviates in azimuth, the system immediately issues an alarm, and the operator can adjust the installation equipment accordingly to ensure the verticality and azimuth accuracy of the pipe curtain.

[0032] Among them, the advanced installation equipment used includes directional drilling rigs and pipe jacking machines. The directional drilling rig with high-precision guiding function is used for pipe curtain installation. The directional drilling rig is equipped with an advanced guiding system. By installing a probe at the front end of the drill bit, the position, angle, depth and other parameters of the drill bit can be measured in real time. These parameters are fed back to the operating console of the drilling rig through wireless or wired transmission. The operator accurately controls the drilling direction and propulsion speed of the drilling rig based on the feedback data. The directional drilling rig can also automatically adjust the drilling parameters according to different geological conditions to ensure that the pipe curtain can be accurately installed even under complex geological conditions.

[0033] Pipe jacking machine: For some pipe curtains with larger diameters, pipe jacking machines are used for construction. The pipe jacking machine is equipped with a high-precision jacking system and a deviation correction device. During the jacking process, the jacking direction and jacking force of the pipe jacking machine are monitored in real time through the sensor installed at the tail of the pipe jacking machine. When the pipe jacking machine deviates, the deviation correction device can be quickly started and the posture of the pipe jacking machine can be adjusted to return the pipe curtain to the correct design trajectory. The jacking speed and jacking force of the pipe jacking machine can also be precisely controlled to ensure the construction quality and accuracy of the pipe curtain.

[0034] The specific construction method is: Pre-drilling construction: Before the pipe curtain is installed, pre-drilling construction is carried out. According to the designed position and diameter of the pipe curtain, a geological drill is used to drill a pilot hole. The role of the pilot hole is to provide precise guidance for the installation of the pipe curtain and reduce the deviation of the pipe curtain during the installation process. During the pilot hole drilling process, measuring equipment such as total stations and gyroscopes are also used for real-time monitoring to ensure the accuracy of the pilot hole. After the pilot hole is completed, the pipe curtain is installed into the pilot hole by jacking or drilling, which effectively improves the accuracy of the pipe curtain construction.

[0035] Segmented construction and measurement review: The pipe curtain construction is divided into several sections. After each section is completed, a comprehensive measurement review is carried out. At the joints of each section of the pipe curtain, high-precision measuring instruments are used to measure the docking deviation of the pipe curtain, including axial deviation and radial deviation. If the deviation exceeds the allowable range, it is adjusted in time. Through segmented construction and measurement review, deviations in the construction process can be discovered and corrected in time to ensure the construction accuracy of the entire pipe curtain.

[0036] Therefore, through the above-mentioned specific steps and equipment, the combined support system specially arranged in the present invention is realized to effectively bear the vertical load above the underground space.

[0037] Step 7: Backfill the pipe curtain working shaft 2 and the temporary shaft 19 foundation pit.

[0038] Step 8: Under the protection of the combined support consisting of the pipe curtain 4, retaining piles 6 or underground continuous wall, cap beam 5 and top longitudinal beam 14, the underground space structure 7 is constructed. Specifically, the earth can be excavated downward to 500 mm below the first inner support 21, and the first inner support 21 is constructed. The earth can be excavated downward to 500 mm below the second inner support 22, and the second inner support 22 is constructed. When the remaining soil is excavated to the bottom elevation of the bottom plate 13, the bottom plate 13 is constructed, the second underground floor side wall 12 is constructed, the middle plate 11 is constructed, the first underground floor side wall 10 is constructed, and the top plate 9 is constructed.

[0039] Step 9: After the construction of the underground space structure 7 is completed, the pipe curtain working shaft 2 and the temporary shaft 19 3.0 m below the ground are removed, and the underground space auxiliary structure is constructed according to the underground space requirements.

[0040] Wherein, in step 2: In order to ensure the verticality and position accuracy of the steel pipe piles and foundations, it is necessary to rationally plan the construction site, set up material stacking areas and equipment parking areas, and adopt advanced measurement and positioning technologies, such as total station positioning.

[0041] Preparation before construction: Accurate measurement and layout: Use a high-precision total station to conduct a comprehensive measurement of the construction site, accurately mark the position and axis of the steel pipe piles according to the design drawings, set obvious control points and control lines, and conduct multiple reviews to ensure the accuracy of the layout.

[0042] Equipment calibration: Comprehensively check and calibrate the piling equipment, especially the verticality adjustment device of the pile frame and the guide device of the pile hammer, to ensure that the equipment can operate normally during the construction process and to ensure the verticality and position accuracy of the piling.

[0043] Construction process control: Set up guiding devices: Set up guiding clamps on the top of the steel pipe pile and the pile frame to guide the steel pipe pile in real time during the piling process to prevent it from shifting and tilting during the driving process.

[0044] Real-time monitoring: Use a total station to conduct real-time monitoring during the piling process, measure the verticality and position deviation of the steel pipe pile at regular intervals (such as every 1 meter of driving), and make adjustments immediately if the deviation exceeds the allowable range.

[0045] Control the piling sequence: According to the geological conditions of the site and the distribution of pile positions, the piling sequence should be reasonably determined to avoid squeezing and offsetting of adjacent piles due to improper piling sequence, which will affect the verticality and position accuracy of the piles.

[0046] Post-construction inspection: Pile testing: After the piling is completed, ultrasonic testing, core drilling and other methods are used to conduct a comprehensive test on the verticality and position accuracy of the steel pipe piles. For piles that do not meet the requirements, remedial measures are taken in a timely manner, such as correcting the deviation or adding piles.

[0047] Therefore, it is possible to provide stable permanent columns and pile foundations for underground space structures.

[0048] In step 3, layered and segmented excavation is adopted, and the specific excavation steps are as follows: First layer excavation: Starting from the wellhead, excavation is carried out using a small excavator according to the layer thickness required by the design (generally 2-3 meters). The middle part of the shaft is excavated first, and then gradually expanded to the periphery to form a pot bottom shape. During the excavation process, the well wall is trimmed while digging to keep it roughly vertical.

[0049] Erection of support: After the first layer of excavation is completed, steel support or shotcrete wall should be installed on the well wall in time to reinforce the well wall and prevent it from collapsing. The spacing and form of the support are determined according to the design requirements and geological conditions.

[0050] Excavation of the second layer and below: Repeat the excavation and support operations of the first layer until the excavation reaches the designed depth. During the excavation of each layer, the excavation depth and the verticality of the shaft wall must be strictly controlled. Every 1-2 meters of excavation, the verticality of the shaft wall is measured using a measuring instrument (such as a laser plumb bob), and any deviation is adjusted in a timely manner.

[0051] Manual trimming: When each layer of excavation approaches the designed depth, manual fine trimming is used to ensure that the well wall is flat and vertical, and the bottom is flat, meeting the design requirements.

[0052] Use advanced earth-moving equipment, such as small excavators, in conjunction with manual finishing.

[0053] This provides working space for subsequent pipe curtain construction.

[0054] In step 5, high-precision pipe curtain installation equipment, such as a guide drill, is used; the mix ratio of the filling material and the pouring process are strictly controlled.

[0055] The raw materials used in the filling material are selected as follows: new high-performance cement is used as the cementitious material, which has the characteristics of high early strength and good stability. At the same time, well-graded quartz sand is selected as the fine aggregate, which has regular particle shape and smooth surface, and can improve the fluidity and density of the filling material.

[0056] Add admixtures: Add appropriate amount of water reducing agent and expansion agent to the filling material. Water reducing agent can effectively reduce the water-cement ratio, improve the strength and durability of the filling material, and increase its fluidity to facilitate pouring construction. Expansion agent can compensate for the shrinkage of the filling material during the hardening process, prevent cracks, and improve the density of the filling.

[0057] Mix ratio test and optimization: Through a large number of indoor tests, the best filling material mix ratio is determined according to different underground space conditions and design requirements. The orthogonal test design method is used to systematically study the influence of factors such as water-cement ratio, sand ratio, and admixture dosage on the performance of filling materials, and establish a relationship model between mix ratio and performance, so as to optimize the best mix ratio that meets engineering requirements.

[0058] The pouring process uses high-pressure rotary jet grouting technology: During the pipe curtain filling process, the high-pressure rotary jet grouting process is used. Through the high-pressure jetting equipment, the filling material prepared according to the mix ratio is injected into the pipe curtain in the form of a high-pressure jet, so that the filling material is fully mixed with the inner wall of the pipe curtain and the surrounding soil, and densely filled. The high-pressure rotary jet grouting technology can effectively improve the density and uniformity of the filling material and enhance the overall performance of the pipe curtain.

[0059] Sectional and layered pouring: According to the length and diameter of the pipe curtain, the pipe curtain is divided into several sections and filled by sectional and layered pouring. When pouring each section, start from the bottom of the pipe curtain and pour upwards gradually. The pouring thickness of each layer is controlled within a certain range (such as 30-50 cm) to ensure that the filling material is evenly dense under the action of gravity.

[0060] Real-time monitoring and quality control: During the pouring process, ultrasonic detectors and other equipment are used to monitor the filling quality in real time. By testing the density and uniformity of the filling material, problems in the pouring process, such as voids and segregation, can be discovered in a timely manner. Once a quality problem is found, the pouring is stopped immediately and corresponding treatment measures are taken, such as adding filling materials and adjusting the pouring process, to ensure that the filling quality of the pipe curtain meets the design requirements.

[0061] This forms an effective support structure and improves the stability of the underground space structure.

[0062] Furthermore, if the span of the underground space is large and the rigidity of the pipe curtain is insufficient, when excavating the soil downward, steel bars or steel strands can be inserted into the steel pipes of the pipe curtain, and the steel bars or steel strands can be anchored into the top crown beams of the retaining piles or underground continuous wall piles and the top longitudinal beams of the middle columns to increase the overall rigidity of the pipe curtain. Of course, if the rigidity of the pipe curtain is sufficient, it is not necessary to insert steel bars or steel strands into the steel pipes of the pipe curtain.

[0063] Among them, Figure 2 As shown, the pipe curtain 4 includes a plurality of fixedly connected steel pipes 40, one end of the steel pipe 40 is provided with a female locking buckle 41, and the other end is provided with a male locking buckle 42 that can be buckled and locked with the female locking buckle 41, so that a plurality of pipe curtains 4 can achieve different width requirements through the matching locking of the male locking buckle 42 and the female locking buckle 41.

[0064] It is obvious that the above description and record are only examples and are not intended to limit the disclosure, application or use of the present invention. Although the embodiments have been described in the embodiments and described in the drawings, the present invention is not limited to the specific examples of the teachings of the present invention as the best mode currently considered by the drawings and described in the embodiments, and the scope of the present invention will include any embodiment falling within the previous description and the attached claims.

Claims

1. A method for quickly constructing an underground space under an existing road, wherein there is a green belt in the middle of the existing road, characterized in that The following steps are included: Step 1: Drive retaining piles or underground continuous walls from the ground outside the underground space structure; Step 2: Construct steel pipe piles and their steel pipe column foundations in the green belt in the middle of the existing road; Step 3: Construct a temporary shaft in the central green belt of the road, construct a locking ring beam, excavate the soil and set up a steel grid. The bottom of the temporary shaft foundation pit is flush with the bottom elevation of the top longitudinal beam; Step 4: Construct pipe curtain working wells on both sides of the ground. The pipe curtain working wells are lower than the bottom elevation of the crown beam; Step 5: Install the pipe curtain in the pipe curtain working pit, and place one end of the pipe curtain in the reserved top longitudinal beam in the temporary shaft, with one end of the pipe curtain placed in the top longitudinal beam by no less than 500 mm, and fill the pipe curtain with cement mortar or fine stone concrete; Step 6: After the pipe curtain is constructed, the pile top crown beam is constructed in the pipe curtain working shaft, and the top longitudinal beam above the middle column is constructed in the temporary shaft. The concrete is poured densely, one end of the pipe curtain is restrained in the top longitudinal beam, and the other end of the pipe curtain is placed in the crown beam, and the distance inside the crown beam is not less than 500 mm; Step 7: Backfill the pipe curtain working pit and temporary shaft foundation pit; Step 8: Under the protection of the combined support consisting of pipe curtains, retaining piles or underground continuous walls, cap beams and top longitudinal beams, the underground space structure is constructed.

2. The method for rapidly constructing an underground space under an existing road as claimed in claim 1, characterized in that: It also includes step 9: after the construction of the underground space structure is completed, the pipe curtain working shaft and temporary shaft 3.0 m below the ground are removed, and the underground space auxiliary structure is constructed according to the needs of the underground space.

3. The method for rapidly constructing an underground space under an existing road as claimed in claim 1, characterized in that: The construction of the underground space structure in step 8 is specifically as follows: when the earth is excavated downward to 500mm below the first internal support, the first internal support is constructed; when the earth is continued to be excavated downward to 500mm below the second internal support, the second internal support is constructed; when the remaining soil is excavated to the bottom elevation of the bottom plate, the bottom plate is constructed, the side wall of the second underground floor is constructed, the middle plate is constructed, the side wall of the first underground floor is constructed, and the top plate is constructed.

4. The method for rapidly constructing an underground space under an existing road as claimed in claim 1, characterized in that: When the span of the underground space is large and the rigidity of the pipe curtain is insufficient, steel bars or steel strands are inserted into the steel pipes of the pipe curtain. The steel bars or steel strands are anchored into the top crown beams of the retaining piles or underground continuous wall piles and the top longitudinal beams of the central columns to increase the overall rigidity of the pipe curtain.

5. The method for rapidly constructing an underground space under an existing road as claimed in claim 1, characterized in that: The diameter of the pipe curtain is 108 mm to 1000 mm.

6. The method for rapidly constructing an underground space under an existing road as claimed in claim 1, characterized in that: The pipe curtain comprises a plurality of fixedly connected steel pipes, a female locking buckle is provided at one end of the pipe curtain, and a male locking buckle which can be buckled and locked with the female locking buckle is provided at the other end, so that a plurality of pipe curtains can achieve different requirements through the matching locking of the male locking buckle and the female locking buckle.

7. The method for rapidly constructing an underground space under an existing road as claimed in claim 1, characterized in that: In step 6, through the pile top crown beam and the top longitudinal beam, the two ends of the pipe curtain are respectively constrained in the top longitudinal beam and the crown beam to form a joint support system; The specific construction method is: Pre-drilling construction: Before the pipe curtain is installed, pre-drilling construction is carried out. According to the designed position and diameter of the pipe curtain, a geological drill is used to drill a pilot hole. The role of the pilot hole is to provide precise guidance for the installation of the pipe curtain and reduce the deviation of the pipe curtain during the installation process. During the drilling of the pilot hole, measuring equipment such as a total station and a gyroscope are also used for real-time monitoring to ensure the accuracy of the pilot hole. After the pilot hole is completed, the pipe curtain is installed in the pilot hole by jacking or drilling, which effectively improves the accuracy of the pipe curtain construction; Segmented construction and measurement review: The pipe curtain construction is divided into several sections. After each section is completed, a comprehensive measurement review is carried out. At the joints of each section of the pipe curtain, high-precision measuring instruments are used to measure the docking deviation of the pipe curtain, including axial deviation and radial deviation.

8. The method for rapidly constructing an underground space under an existing road as claimed in claim 1, characterized in that: Step 2 also includes: Preparation before construction: Accurate measurement and layout: Use a high-precision total station to conduct a comprehensive measurement of the construction site, accurately mark the position and axis of the steel pipe piles according to the design drawings, set obvious control points and control lines, and conduct multiple reviews to ensure the accuracy of the layout; Construction process control: Setting up guiding devices: Setting up guiding fixtures on the top of the steel pipe pile and the pile frame to guide the steel pipe pile in real time during the piling process to prevent it from deflecting and tilting during the driving process; Real-time monitoring: Use a total station to conduct real-time monitoring during the piling process, measure the verticality and position deviation of the steel pipe piles at regular intervals, and make adjustments immediately if the deviation exceeds the allowable range; Post-construction inspection: Pile testing: After the piling is completed, ultrasonic testing, core drilling and other methods are used to conduct a comprehensive test on the verticality and position accuracy of the steel pipe piles. For piles that do not meet the requirements, remedial measures are taken in a timely manner, such as correcting the deviation or adding piles.

9. The method for rapidly constructing an underground space under an existing road as claimed in claim 1, characterized in that: In step 3, layered and segmented excavation is adopted, and the specific excavation steps are as follows: First layer excavation: starting from the wellhead, excavate the middle part of the shaft first according to the layer thickness required by the design, and then gradually expand to the periphery to form a pot bottom shape; Erection of support: After the first layer of excavation is completed, steel support or shotcrete wall is installed on the shaft wall to reinforce the shaft wall and prevent the shaft wall from collapsing; Excavation of the second layer and below: Repeat the excavation and support operations of the first layer until the excavation reaches the designed depth.

10. The method for rapidly constructing an underground space under an existing road as claimed in claim 1, characterized in that: In step 5, high-performance cement is used as the cementitious material for the filling material, and quartz sand is selected as the fine aggregate, and an appropriate amount of water reducing agent and expansion agent are added to the filling material; The pouring process adopts high-pressure rotary jet grouting technology: During the pipe curtain filling process, high-pressure rotary jet grouting technology is adopted, and the pouring is carried out in sections and layers: According to the length and diameter of the pipe curtain, the pipe curtain is divided into several sections, and the filling is carried out by section and layer pouring method.

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