Construction control method for large-diameter shield under-crossing civil house in composite stratum

Abstract

The invention discloses a construction control method for underneath crossing of a civil house by a large-diameter shield in a composite stratum, and relates to the technical field of shield method construction, and the construction control method comprises the following steps: S1, ground WSS pre-grouting reinforcement; s2, selecting a tunneling mode; s3, tunneling parameter control; s4, in-hole advanced grouting reinforcement is conducted; s5, middle shield radial hole grouting is carried out; s6, synchronous grouting and secondary grouting are carried out; and S7, tracking and compensating grouting. According to the construction control method for the large-diameter shield underneath pass of the civil house in the composite stratum, by conducting grouting reinforcement on the ground and in the tunnel, the house foundation underneath stratum and the tunnel top stratum are effectively reinforced, the overall stability of the composite stratum is improved, and the construction risk of underneath pass of the house is reduced; therefore, the large-diameter shield tunneling machine can safely and smoothly penetrate through the house under the composite stratum.

Description

Technical Field

[0001] The invention relates to the technical field of shield construction, and in particular to a construction control method for a large-diameter shield tunnel under a residential building in a composite stratum. Background Art

[0002] With the rapid development of society, the construction of intercity railways is increasing. With higher operating speeds, the corresponding tunnel diameters are also increasing. The length of a single tunnel section is also relatively long. Long-distance shield tunneling faces various underground and ground construction risks. When a large-diameter shield tunnel is constructed under a composite stratum, ensuring the safety and stability of the house is the primary construction goal. When a large-diameter shield tunnel is constructed under a composite stratum, the stratum stability is poor, the soil is easy to peel off, and the air loss is large, which can easily cause the excavation volume to exceed the control, resulting in the settlement and collapse of the ground house, and the construction safety risk is extremely high.

[0003] In the construction of intercity railways, due to the long lines, complex geological conditions in the sections, and the large-diameter shield machines used, they also need to pass under various buildings and structures, and the safety of the construction under the buildings must be ensured.

[0004] How to develop a construction control method for a large-diameter shield tunnel under a residential building in a composite stratum, and adopt technical means to keep the stratum stable when passing through a residential building in a composite stratum, so as to pass through the house safely and smoothly, has become a technical problem that needs to be urgently solved by technical personnel in this field. Summary of the invention

[0005] The purpose of the present invention is to provide a construction control method for a large-diameter shield machine passing through residential buildings in a composite stratum, so as to solve the problems listed in the background technology.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] The present invention provides a construction control method for a large-diameter shield machine in a composite stratum passing through a residential building, comprising the following steps:

[0008] S1. Ground WSS pre-grouting reinforcement

[0009] Use WSS drilling and grouting machine to reinforce the foundation of the house;

[0010] S2, Excavation mode selection

[0011] Tunneling is carried out using earth pressure balance mode;

[0012] S3. Excavation parameter control

[0013] During the excavation process, strictly control the slag output and excavation torque, do a good job of slag temperature measurement and slag sample analysis, strengthen construction monitoring, and dynamically adjust the excavation parameters according to the monitoring data in a timely manner;

[0014] S4. Advance grouting reinforcement in the tunnel

[0015] Due to the restrictions of ground buildings and surrounding environment, it is impossible to carry out pre-grouting reinforcement in the entire underpass tunnel. Therefore, during the excavation process, advance grouting is carried out in the tunnel to reinforce the soil in front of the cutterhead.

[0016] S5, radial hole grouting

[0017] During the excavation process, the radial holes in the middle shield are used to inject chemical slurry around the shield body to fill the gap between the shield body and the surrounding strata in time. The chemical slurry wraps the shield body to form a water stop ring, blocking the water inlet from the rear pipe segment and the air leakage channel at the shield body position, so as to achieve the purpose of stabilizing the chamber pressure.

[0018] S6, synchronous grouting and secondary grouting

[0019] Strengthen synchronous grouting and secondary grouting. During the penetration process, ensure that the synchronous grouting is densely filled. After 3-5 rings of the shield tail are removed, secondary grouting is carried out in time to more effectively fill the gap between the pipe segment and the formation.

[0020] S7, tracking compensation grouting

[0021] Geological radar is used to scan the top segment wall, and additional grouting is performed on loose locations. If necessary, steel pipes are used to fill and grout the stratum.

[0022] Preferably, the grouting depth in step S1 ranges from 3 meters above the tunnel top to 1 meter below the tunnel top.

[0023] Compared with the prior art, the beneficial technical effects of the present invention are:

[0024] The present invention provides a construction control method for a large-diameter shield machine passing under a residential building in a composite stratum. By grouting the ground and the inside of a hole, the stratum under the foundation of the house and the stratum on the top of the tunnel are effectively reinforced, thereby improving the overall stability of the composite stratum and reducing the construction risk of passing under the house, so that the large-diameter shield machine can pass under the house safely and smoothly under the composite stratum. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described below in conjunction with the accompanying drawings.

[0026] Figure 1 This is a construction process flow chart of a construction control method for a large-diameter shield tunnel under a residential building in a composite stratum according to the present invention;

[0027] Figure 2 It is a schematic diagram of the construction scheme of the present invention;

[0028] Figure 3 It is the excavation control parameter of the underpass section of the present invention. DETAILED DESCRIPTION

[0029] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] like Figure 1-3 As shown, a construction control method for a large-diameter shield tunnel under a residential building in a composite stratum comprises the following steps:

[0031] S1. Ground WSS pre-grouting reinforcement

[0032] Drilling and grouting are carried out around the house, using single-liquid slurry, the grouting pressure is controlled at 1.0-1.5Mpa, backward grouting, water-cement ratio is 1:1, the grouting depth is 3 meters above the tunnel top and 1 meter below the tunnel top, and double-liquid slurry is used to seal the hole;

[0033] S2, Excavation mode selection

[0034] The section was constructed using an earth pressure / TBM dual-mode shield, which passed under the composite stratum and under the house. The excavation was carried out in earth pressure balance mode, and the liquid level of the slag in the bin was kept above 3 / 4. The air pressure auxiliary mode was used to maintain earth pressure balance.

[0035] S3. Excavation parameter control

[0036] During the excavation process, the bin pressure is controlled between the active earth pressure and the static earth pressure of the stratum, and the bin pressure fluctuation is no more than 0.3 bar. The stability of the tunnel face is observed visually by using the soil bin, and the slag discharge is strictly controlled by means of gantry crane weighing, belt weighing, theoretical calculation, and slag sample analysis. When the slag discharge exceeds the control, the soil in front of the tunnel face is immediately reinforced by grouting using advance grouting in the tunnel. When the torque and slag temperature are too large during the excavation process, dispersant is injected into the soil bin to soak the cutterhead to prevent the cutterhead from forming mud cakes.

[0037] S4. Advance grouting reinforcement in the tunnel

[0038] When the cutter head of the shield machine reaches the bottom of the house, the ground below the house is further reinforced by grouting in advance. Reverse grouting, phosphoric acid sealing, double slurry reinforcement of the ground are adopted. The water-cement ratio is 1:1, the drilling depth is 16 meters, and there are 3 advance grouting holes on the upper part of the shield machine. Two of them are selected for grouting. The grouting is controlled by the soil bin pressure and the grouting machine pressure. The grouting pressure shall not be higher than 2MPa, and the soil bin pressure shall not be higher than the shutdown pressure of more than 1bar. After the soil bin pressure reaches the control pressure, the cutter head is immediately turned to discharge the bin and reduce the pressure, and the drill rod is retreated;

[0039] S5, radial hole grouting

[0040] During the excavation process, chemical slurry (water glass + phosphoric acid AB mixture) is injected through the radial holes of the middle shield, which can effectively stabilize the excavation chamber pressure, fill the outer cavity of the shield in time, and block the gas leakage channel of the formation at the middle shield position; the chemical slurry is in a colloidal state at the initial stage of fusion, which can be stacked and penetrated into the formation to effectively fill the pores of the formation. In the later stage, it is in a crystalline state and has a certain self-stabilizing ability. It can be replaced by high-viscosity bentonite or clay effect;

[0041] S6, synchronous grouting and secondary grouting

[0042] During the crossing, the quality of each ring of slurry shall be strictly checked. Under the premise that the amount of each ring is sufficient, the proportion of cement and viscosity of the slurry shall be appropriately adjusted to reduce the setting time of synchronous grouting; grouting holes shall be reserved on the ground grouting background and the pipe segments in the tunnel, and secondary grouting shall be carried out at the position of 3-5 rings out of the shield tail. Open hole grouting shall be carried out every other ring, and the grouting point shall be selected at the upper point. The slurry shall be cement + water glass double liquid slurry; the grouting pressure shall be controlled at 0.4Mpa; the material ratio of synchronous grouting is shown in the following table:

[0043] Synchronous grouting material ratio (normal excavation stage)

[0044] Cement(kg) Fly ash(kg) Bentonite(kg) Sand (kg) Water (kg) 200 380 12.5 600 300

[0045] S7, tracking compensation grouting

[0046] Carry out top geological radar scanning on the pipe segments under the house. For locations where there are cavities, use grouting holes for compensatory grouting or implant steel flower pipes for grouting to fill the stratum gaps in time.

[0047] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variation thereof are intended to cover non-exclusive inclusion, so that a process, method, article or seal including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or seal.

[0048] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A construction control method for a large-diameter shield tunnel under a residential building in a composite stratum, characterized by: The steps include: S1. Ground WSS pre-grouting reinforcement Use WSS drilling and grouting machine to reinforce the foundation of the house; S2, Excavation mode selection Tunneling is carried out using earth pressure balance mode; S3. Excavation parameter control During the excavation process, strictly control the slag output and excavation torque, do a good job of slag temperature measurement and slag sample analysis, strengthen construction monitoring, and dynamically adjust the excavation parameters according to the monitoring data in a timely manner; S4. Advance grouting reinforcement in the tunnel Due to the restrictions of ground buildings and surrounding environment, it is impossible to carry out pre-grouting reinforcement in the entire underpass tunnel. Therefore, during the excavation process, advance grouting is carried out in the tunnel to reinforce the soil in front of the cutterhead. S5, radial hole grouting During the excavation process, the radial holes in the middle shield are used to inject chemical slurry around the shield body to fill the gap between the shield body and the surrounding strata in time. The chemical slurry wraps the shield body to form a water stop ring, blocking the water inlet from the rear pipe segment and the air leakage channel at the shield body position, so as to achieve the purpose of stabilizing the chamber pressure. S6, synchronous grouting and secondary grouting Strengthen synchronous grouting and secondary grouting. During the penetration process, ensure that the synchronous grouting is densely filled. After 3-5 rings of the shield tail are removed, secondary grouting is carried out in time to more effectively fill the gap between the pipe segment and the formation. S7, tracking compensation grouting Geological radar is used to scan the top segment wall, and additional grouting is performed on loose locations. If necessary, steel pipes are used to fill and grout the stratum.

2. The construction control method of a large-diameter shield tunnel under a residential building in a composite stratum according to claim 1 is characterized by: The grouting depth in step S1 ranges from 3 meters above the tunnel top to 1 meter below the tunnel top.

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