Construction method for shield tunneling machine to pass through expressway under narrow space condition

Abstract

The invention provides a construction method for a shield to pass through an expressway under a narrow space condition. The method aims at the specific engineering scene that the shield machine passes through the expressway under the narrow space condition. Compared with the prior art, through the technical means of shield tunneling machine customization design, a soil bin visualization system, advanced geological forecast and the like, the tunneling process can be more accurately controlled, disturbance to the stratum is reduced, and the tunneling accuracy and controllability are greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of shield construction in tunnel engineering, and in particular to a construction method for a shield machine to pass under a highway under narrow space conditions. Background Art

[0002] In urban construction, more and more shield tunneling projects are under highways. However, shield construction in narrow space conditions faces many challenges. On the one hand, the narrow space limits the flexibility of construction operations and places higher requirements on the size and performance of the shield machine. It is necessary to ensure that the shield machine can dig safely and stably in a limited space. On the other hand, when underpassing the highway, ground settlement needs to be strictly controlled to ensure the structural safety and normal operation of the highway. Traditional construction methods have certain limitations in dealing with these challenges. For example, it is difficult to accurately control the shield tunneling parameters, resulting in excessive ground settlement; the prediction and monitoring of the stratum conditions are not accurate enough, which increases the construction risk.

[0003] Therefore, a more effective construction method is needed to ensure the safety and smooth progress of construction. Summary of the invention

[0004] The purpose of the present invention is to provide a construction method for a shield machine to pass under a highway in a narrow space, so as to solve the problems existing in the prior art.

[0005] The technical solution adopted to achieve the purpose of the present invention is as follows: a construction method for a shield tunnel under a highway under narrow space conditions, comprising the following steps:

[0006] 1) Customized shield machine design. The shield machine is customized according to the characteristics of the stratum and the requirements of the structure under the expressway. The shield machine includes a soil bin visualization system, an advanced geological prediction system, a segment cavity scanning system, a slag automatic weighing and volume scanning system, an advanced grouting reinforcement system, and a synchronous grouting system. The synchronous grouting system is configured at the shield tail.

[0007] 2) Setting up a test section before construction. Before officially crossing the expressway, excavation of the test section is carried out first, and excavation parameters are collected and summarized to optimize subsequent construction. The excavation parameters include propulsion speed, thrust, torque, synchronous grouting pressure, grouting volume, slurry initial setting time and ratio.

[0008] 3) Set up surface monitoring points. Set up surface vertical displacement and deep settlement monitoring points on the roadbed and green belts on both sides of the expressway for automated real-time monitoring.

[0009] 4) Based on the parameters summarized in the test section, the full earth pressure balance method is used for excavation. In the process of the shield machine passing under the expressway, the ground settlement and shield posture are monitored in real time, and the continuous excavation method is adopted to reduce the disturbance of the stratum. During the advancement of the shield machine, the shield tail is synchronously grouted to inject filling slurry into the annular building space between the pipe segment and the stratum to control the settlement of the shield tail. The stability and accuracy of the excavation process are ensured by advanced geological prediction, pipe segment cavity scanning, slag weighing and volume scanning. The surface settlement is reduced by optimizing the operating parameters of the shield machine. Fill the mud-reducing material during the excavation process to control the settlement above the shield body.

[0010] Furthermore, the advanced geological prediction system adopts a method combining geological survey method, advanced drilling method and geophysical exploration method, and uses reflected elastic wave detection technology to predict the geological conditions in front of the shield, thereby reducing the risk of geological disasters.

[0011] Furthermore, the segment cavity scanning system uses a geological radar method to scan the cavity behind the shield segment to ensure the density of the synchronous grouting.

[0012] Furthermore, the slag automatic weighing and volume scanning system is configured on the continuous belt conveyor. The slag automatic weighing and volume scanning system monitors the slag output in real time and controls over-excavation or under-excavation.

[0013] Furthermore, a grouting platform is reserved at the front end of the shield machine. An advance grouting hole is set at the front end of the shield machine. The advance grouting reinforcement system is arranged on the grouting platform. The advance grouting reinforcement system is used to perform advance grouting reinforcement to prevent stratum instability.

[0014] Furthermore, in step 3), the surface monitoring points also include retaining wall vertical displacement monitoring points.

[0015] Furthermore, in step 4), after the segment is released from the shield tail, secondary grouting is performed using a trolley to strengthen the settlement control around the segment.

[0016] Furthermore, grouting holes are added on the underpass segment. In step 4), the surrounding strata are further grout-reinforced.

[0017] The technical effects of the present invention are unquestionable:

[0018] A. In terms of precise control of shield tunneling, through customized shield machine design, soil bin visualization system and advanced geological prediction and other technical means, the tunneling process can be controlled more accurately compared with existing technologies, reducing disturbance to the strata, greatly improving the accuracy and controllability of tunneling;

[0019] B. In terms of effective control of ground settlement, the full earth pressure balance mode excavation, shield filling mud effect, synchronous grouting and secondary grouting control measures have more significant control effects on ground settlement than existing technologies, effectively ensuring the safety of the expressway structure;

[0020] C. In terms of improving construction safety, measures such as setting up a pre-underpass test section, strengthening construction monitoring, and using an automated monitoring system can promptly detect and resolve problems that arise during construction, thereby improving construction safety compared to existing technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a flow chart of the construction method;

[0022] Figure 2 This is a schematic diagram of a shield machine. DETAILED DESCRIPTION

[0023] The present invention is further described below in conjunction with the embodiments, but it should not be understood that the above subject matter of the present invention is limited to the following embodiments. Without departing from the above technical ideas of the present invention, various substitutions and changes are made according to the common technical knowledge and customary means in the art, which should all be included in the protection scope of the present invention.

[0024] Embodiment 1:

[0025] This embodiment provides a construction method for a shield machine to pass under a highway in a narrow space, comprising the following steps:

[0026] 1) Customized shield machine design. The shield machine is customized according to the characteristics of the stratum and the requirements of the structures under the expressway. The shield machine includes a soil bin visualization system, an advanced geological prediction system, a segment cavity scanning system, a slag automatic weighing and volume scanning system, an advanced grouting reinforcement system, and a synchronous grouting system. The synchronous grouting system is configured at the shield tail. The advanced geological prediction system uses a combination of geological survey method, advanced drilling method and geophysical method, and uses reflected elastic wave detection technology to predict the geological conditions in front of the shield to reduce the risk of geological disasters. The segment cavity scanning system uses the geological radar method to scan the cavity behind the shield segment to ensure the density of synchronous grouting. The slag automatic weighing and volume scanning system is configured on the continuous belt conveyor. The slag automatic weighing and volume scanning system monitors the slag output in real time to control over-excavation or under-excavation. A grouting platform is reserved at the front end of the shield machine. An advanced grouting hole is set at the front end of the shield. The advanced grouting reinforcement system is arranged on the grouting platform. The advance grouting reinforcement system is used to carry out advance grouting reinforcement to prevent ground instability.

[0027] The custom design of the shield machine is based on the special requirements of narrow space and underpasses of highways. The various systems are interrelated and mutually influential, forming an organic whole. For example, the soil bin visualization system provides the shield driver with real-time observation of the excavation bin status, helping him to adjust the operation according to the actual situation and ensure solid soil pressure excavation. This is combined with geological information provided by other systems such as the advanced geological prediction system, so that the shield machine can better adapt to the changes in the formation and avoid safety problems caused by improper operation or lack of understanding of the formation conditions.

[0028] 2) Setting up a test section before construction. Before officially crossing the expressway, excavation of the test section is carried out first, and excavation parameters are collected and summarized to optimize subsequent construction. The excavation parameters include propulsion speed, thrust, torque, synchronous grouting pressure, grouting volume, slurry initial setting time and ratio.

[0029] 3) Set up surface monitoring points. Set up surface vertical displacement, deep settlement monitoring points and retaining wall vertical displacement monitoring points on the roadbed and green belts on both sides of the expressway for automated real-time monitoring.

[0030] 4) Based on the parameters summarized in the test section, the full earth pressure balance method is used for excavation. In the process of the shield machine passing under the expressway, the ground settlement and shield posture are monitored in real time, and the continuous excavation method is adopted to reduce the disturbance of the stratum. During the advancement of the shield machine, the shield tail is synchronously grouted to inject filling slurry into the annular building space between the pipe segment and the stratum to control the settlement of the shield tail. The stability and accuracy of the excavation process are ensured by advanced geological prediction, pipe segment cavity scanning, slag weighing and volume scanning. The surface settlement is reduced by optimizing the operating parameters of the shield machine. Fill the mud-reducing material during the excavation process to control the settlement above the shield body.

[0031] It is worth mentioning that in the specific engineering scenario of shield tunneling under the highway in narrow space conditions, the soil bin visualization system has become the key basis for the shield driver to judge the state of the slag in the soil bin and adjust the excavation parameters. Through real-time observation, the driver can promptly detect abnormal conditions, such as the accumulation of slag and whether there is a cake phenomenon, and adjust the parameters such as the cutter head speed and propulsion speed accordingly to ensure the pressure balance in the soil bin and the smooth progress of excavation.

[0032] The advanced geological prediction system adopts a combination of geological survey, advanced drilling, and geophysical exploration (such as the shield machine equipped with rock-breaking source elastic wave reflection method (HSP)), which is more comprehensive and in-depth than conventional geological prediction. This is because under narrow space conditions, the construction tolerance rate is low, and it is necessary to accurately understand the geological conditions in front of the tunnel in advance, including stratum lithology, geological structure, unfavorable geology and special rock and soil information, so as to adjust the construction plan in time, such as taking corresponding safety measures when encountering harmful gases (shallow natural gas) to avoid engineering accidents caused by geological disasters. When constructing in a narrow space, accurately grasping the geological conditions in front of the tunnel is crucial to avoid geological disasters and optimize the construction plan. Through the combination of multiple methods, we can have a more comprehensive and in-depth understanding of the stratum conditions, discover potential risks in advance, such as the presence of harmful gases (shallow natural gas), unstable stratum areas, etc., and take corresponding measures.

[0033] The segment cavity scanning system uses the geological radar method to detect the cavity behind the segment and infer whether the synchronous grouting is full, which plays an important role in ensuring the stability of the tunnel structure. In the construction of narrow spaces, higher requirements are placed on the accuracy and quality of the tunnel structure. Timely detection and treatment of the cavity behind the segment can prevent excessive deformation of the stratum and ensure the safe operation of the highway. In a narrow space, any minor defect in the tunnel structure may lead to serious consequences. Therefore, strict control of the grouting quality behind the segment is a key link in ensuring construction quality. By timely detecting the cavity and taking remedial measures to ensure the compactness of the synchronous grouting, the occurrence of stratum deformation and tunnel structure diseases can be effectively prevented.

[0034] Automatic weighing and volume scanning system for slag is configured on the continuous belt conveyor to monitor the slag discharge in real time and control over / under excavation. In a narrow space, accurate control of the slag discharge is crucial to maintaining the stability of the soil around the shield machine. If the slag discharge is too much, it may cause excessive ground settlement; if the slag discharge is too little, it may cause the soil in front of the shield machine to be squeezed, affecting the excavation. Through the real-time monitoring of the system, the excavation parameters can be adjusted in time to ensure construction safety. In narrow space construction, the stability of the stratum is extremely sensitive to changes in the slag discharge. Over-excavation may cause excessive ground settlement, and under-excavation may affect the advancement of the shield machine. By accurately monitoring the slag discharge and combining the information provided by other systems (such as geological conditions, shield posture, etc.), the excavation parameters can be optimized in real time to ensure the stability of the stratum during construction.

[0035] The advance grouting reinforcement system is an important measure set up to deal with unstable strata that may be encountered during construction in narrow spaces. When the shield machine passes through complex strata or passes under important structures such as highways, advance grouting can be used to reinforce the strata in advance, improve the strength and stability of the strata, and reduce the risk of stratum settlement and deformation during shield excavation. The reservation of a carrying platform for advance grouting reinforcement when necessary reflects the flexibility and foresight of the construction plan. When constructing in complex strata and key areas such as underpasses of highways, stratum reinforcement is an important measure to ensure construction safety. According to the actual stratum conditions and construction monitoring results, the timely use of the carrying platform for advance grouting reinforcement can effectively improve the strength and stability of the stratum and reduce the risks during shield excavation.

[0036] Each system cooperates with each other to form a closed-loop control system. For example, the information provided by the advanced geological prediction system can help shield machine operators adjust parameters such as soil bin pressure before excavation, and provide a basis for soil improvement (such as selecting appropriate additives according to the ground conditions); during the excavation process, the soil automatic weighing and volume scanning system monitors the amount of slag, and combines the soil state observed by the soil bin visualization system to determine whether the excavation is normal. If abnormalities occur, timely adjustments are made; the segment cavity scanning system detects the grouting behind the segment. If it is found to be incomplete, additional grouting can be carried out in time, and the grouting process will affect the stability of the formation, which is then interconnected with the advanced grouting reinforcement system to ensure the stability of the formation and tunnel structure during the entire construction process. This collaborative working method embodies innovative applications in specific engineering scenarios, aiming to solve key problems in the construction of shield tunnels under highways in narrow spaces, improve the safety, accuracy and efficiency of construction, and is essentially different from the conventional simple combination working method.

[0037] Embodiment 2:

[0038] The main contents of this embodiment are the same as those of embodiment 1, wherein, in step 4), after the segment is released from the shield tail, secondary grouting is performed using a trolley to strengthen the settlement control around the segment. Further grouting reinforcement is performed on the surrounding strata.

[0039] Embodiment 3:

[0040] The main contents of this embodiment are the same as those of Embodiment 2, wherein a pre-underpassing test section is set up, and trial excavation is carried out from the start of the shield machine to before it passes under the bypass to collect and summarize excavation parameters for optimizing subsequent construction; then, during the shield underpass, excavation is carried out in a full earth pressure balance mode according to the parameters summarized in the test section, and strict control is carried out through means such as a soil bin visualization system and precise measurement of slag output to ensure safety and controllability; at the same time, the shield machine is stopped in advance before passing under the bypass to conduct a comprehensive overhaul and debugging to ensure continuous excavation, reduce the number of shutdowns and repeated disturbances to the stratum to control ground settlement; in this process, radial holes are set around the shield body, and during the underpass, the middle shield is synchronously filled with mud to control the upper settlement and reduce ground settlement; a synchronous grouting pipeline is set at the shield tail to ensure timely grouting to control settlement; the shield machine's built-in double-piston grouting pump is used to inject filling at the shield tail to fill the annular gap between the segment and the stratum, control stratum deformation, etc., and the tunnel is adjusted according to the advance ground According to the quality forecast, excavation and monitoring conditions, advance grouting reinforcement is carried out when necessary to enhance the stability of the stratum and reduce the risk. After the segment is out of the shield tail, a secondary grouting machine is configured on the trolley to carry out secondary grouting reinforcement according to the ratio of single-liquid slurry (cement: water = 1:0.8) and double-liquid slurry (cement: water glass: water = 1:0.06:0.8) to control the nearby settlement and ensure repeatability (single-liquid slurry is used for the first time, and subsequent grouting can be selected and supplemented multiple times according to the needs of monitoring and settlement control, and double-liquid slurry is used in emergencies). Grouting holes are added to the segment of the underpass section. If necessary, further grouting is carried out to reinforce the surrounding strata to improve stability and control ground settlement. Monitoring points such as surface vertical displacement and deep soil settlement are set on the roadbed on both sides of the ring expressway and the green belt in the middle. Automated monitoring is used to transmit data in real time, so that the automated monitoring system can accurately monitor ground settlement and shield posture in real time and find problems in time and take measures to solve monitoring problems.

Claims

1. A construction method for shield tunneling under a highway in a narrow space, characterized in that: The following steps are involved: 1) Customized shield machine design: The shield machine is customized according to the characteristics of the stratum and the requirements of the structure under the expressway; the shield machine includes a soil bin visualization system, an advanced geological prediction system, a segment cavity scanning system, a slag automatic weighing and volume scanning system, an advanced grouting reinforcement system and a synchronous grouting system; the synchronous grouting system is configured at the shield tail; 2) Setting up the test section before construction: Before officially crossing the expressway, excavation of the test section is carried out first, and excavation parameters are collected and summarized to optimize subsequent construction; the excavation parameters include propulsion speed, thrust, torque, synchronous grouting pressure, grouting volume, slurry initial setting time and ratio; 3) Set up surface monitoring points: Set up surface vertical displacement and deep settlement monitoring points on the roadbed and green belts on both sides of the expressway to conduct automatic real-time monitoring; 4) Adopt full earth pressure balance mode for excavation according to the parameters summarized in the test section; when the shield machine passes under the expressway, the ground settlement and shield posture are monitored in real time, and continuous excavation is adopted to reduce stratum disturbance; during the advancement of the shield machine, the shield tail is synchronously grouted to inject filling slurry into the annular building space between the segment and the stratum to control the settlement of the shield tail; the stability and accuracy of the excavation process are ensured through advanced geological prediction, segment cavity scanning, slag weighing and volume scanning; the surface settlement is reduced by optimizing the operating parameters of the shield machine; and mud-reducing materials are filled during the excavation process to control the settlement above the shield body.

2. A construction method for shield tunneling under a highway in a narrow space according to claim 1, characterized in that: The advanced geological prediction system adopts a method combining geological survey method, advanced drilling method and geophysical exploration method, and uses reflected elastic wave detection technology to predict the geological conditions in front of the shield, thereby reducing the risk of geological disasters.

3. The construction method for shield tunneling under a highway in a narrow space according to claim 1, characterized in that: The segment cavity scanning system uses a geological radar method to scan the cavity behind the shield segment to ensure the density of the synchronous grouting.

4. The construction method for shield tunneling under a highway in a narrow space according to claim 1, characterized in that: The automatic weighing and volume scanning system for slag is arranged on the continuous belt conveyor; the automatic weighing and volume scanning system for slag monitors the slag output in real time and controls over-excavation or under-excavation.

5. The construction method for shield tunneling under a highway in a narrow space according to claim 1, characterized in that: A grouting platform is reserved at the front end of the shield machine; an advance grouting hole is arranged at the front end of the shield; the advance grouting reinforcement system is arranged on the grouting platform; and advance grouting reinforcement is performed through the advance grouting reinforcement system to prevent stratum instability.

6. The construction method for shield tunneling under a highway in a narrow space according to claim 1, characterized in that: In step 3), the surface monitoring points also include the retaining wall vertical displacement monitoring points.

7. The construction method for shield tunneling under a highway in a narrow space according to claim 1, characterized in that: In step 4), after the segment is released from the shield tail, secondary grouting is performed using a trolley to strengthen the settlement control around the segment.

8. The construction method for shield tunneling under a highway in a narrow space according to claim 1, characterized in that: Add grouting holes on the underpass segment; in step 4), further grouting reinforcement is performed on the surrounding strata.

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