PBA-shield method close-range construction disturbance active control method

Abstract

The application discloses a PBA-shield construction method close-range construction disturbance active control method, which comprises the following steps: before the construction of two tunnels, a flexible buffer bag is pre-buried and pre-pressurized in the soil layer between the two small-interval tunnels constructed by different construction methods; after the pre-buried and pre-pressurized flexible buffer bag is completed, tunnel construction is carried out, the PBA construction method tunnel is excavated first, and then the shield method tunnel is constructed; after the tunnel construction is completed, the soil layer between the two tunnels is secondarily reinforced through the flexible buffer bag. The PBA-shield construction method close-range construction disturbance active control method effectively controls the disturbance problem of the two tunnels caused by different construction methods by changing the traditional construction disturbance passive control into active control, and increases the initiative of controlling the construction disturbance while not reducing the effect of the passive control method.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tunnel protection, in particular to a PBA-shield method close-range construction disturbance active control method. BACKGROUND

[0002] In the construction of urban subway tunnels, the disturbance of tunnel construction to the adjacent soil cannot be ignored. For two small-interval tunnels constructed by different methods, the control of such disturbance is particularly important. The commonly used methods for controlling the disturbance of close-range tunnel construction are mainly: (1) reinforcing the soil through triaxial mixing, MJS piles, advanced grouting, etc., to increase the strength of the soil to achieve disturbance control; (2) setting isolation piles, etc., to set an isolation zone between the two tunnels to control the disturbance caused by construction. These two methods essentially achieve the effect of disturbance control by strengthening the soil between the two tunnels. However, during the period from the completion of soil reinforcement to the construction of the tunnel, no matter how much disturbance is caused by actual construction, the disturbance cannot be corrected and intervened. Therefore, such methods can be considered as passive disturbance control means.

[0003] The conventional passive construction disturbance control means cannot guarantee that the disturbance control of tunnel construction is within the standard range in the construction of small-interval tunnels, and cannot correct the disturbance in time after the disturbance exceeds the limit. SUMMARY

[0004] The purpose of the present application is to provide a PBA-shield method close-range construction disturbance active control method, which pre-buries flexible buffer bags between two tunnels constructed by different methods, actively controls the additional soil pressure caused by the advancement of the shield tunneling machine on the construction disturbance of the PBA tunnel by releasing the pressure of the flexible buffer bags, changes the traditional passive control of construction disturbance into active control, effectively controls the disturbance caused by the construction of two tunnels by different methods, and increases the initiative of controlling construction disturbance without reducing the effect of passive control methods.

[0005] To achieve the above-mentioned purpose, the present application provides a PBA-shield method close-range construction disturbance active control method, comprising the following steps:

[0006] S1. Before the construction of the two tunnels, pre-bury and pre-pressurize flexible buffer bags in the soil layer between the two tunnels;

[0007] S2. After the pre-burying and pre-pressurizing of the flexible buffer bags are completed, the tunnel construction is carried out, the PBA method tunnel is excavated first, and the shield method tunnel is constructed later, the additional soil pressure caused by the thrust of the shield machine on the first tunnel can be offset by adjusting the pressure of the flexible buffer bags in real time;

[0008] S3, after the tunnel construction is completed, the soil layer between the two tunnels is reinforced again through the flexible buffer bag to eliminate the safety risk problem caused by the soft interlayer generated by the pre-embedded flexible buffer bag after the construction of the two tunnels is completed;

[0009] The two tunnels are two small-interval tunnels constructed by different construction methods.

[0010] Preferably, the pre-embedding and pre-pressurizing flexible buffer bag in step S1 specifically comprises:

[0011] S11, pre-drilling isolation holes in the soil layer between the two tunnels at a certain distance, and the distance and number of the pre-drilling isolation holes are determined according to the length of the tunnel interval controlled by active construction interference;

[0012] S12, placing the unwatered flexible buffer bag into the predetermined position of the pre-drilling isolation hole;

[0013] S13, the flexible buffer bag is provided with a water injection pipe and a water outlet pipe, and the water injection pipe and the water outlet pipe are connected with the ground pressure control device;

[0014] S14, water is injected into the flexible buffer bag until the pressure of the flexible buffer bag reaches the static earth pressure value of the relative position of the soil layer before excavation, and then the water injection is stopped and the water injection pipe is closed;

[0015] The static earth pressure value σ x is: σ x =K0γz, wherein γ is the unit weight of the soil layer, z is the embedding depth of the flexible buffer bag, K0 is the static earth pressure coefficient, is the internal friction angle of the soil body;

[0016] S15, using cement mortar to completely fill the pre-drilling isolation hole to a dense state.

[0017] Preferably, the tunnel construction body in step S2 comprises:

[0018] S21, the PBA method tunnel is excavated first, and the flexible buffer bag does not need to be operated;

[0019] S22, the shield method is constructed, and when the shield machine excavates to the active control interval where the construction interference is controlled by the flexible buffer bag, the pressure of the flexible buffer bag is adjusted in real time according to the value of the pressure sensor and the earth pressure value of the shield machine on the working face.

[0020] Preferably, the secondary reinforcement method in step S3 is that water is replaced by cement by injecting cement into the flexible buffer bag through the water injection pipe until the flexible buffer bag is completely filled with cement.

[0021] Therefore, the PBA-shield construction method close-range construction disturbance active control method has the following beneficial effects:

[0022] (1) The flexible buffer bag is pre-buried between the two tunnels constructed by different construction methods, and the additional earth pressure generated by the shield tunnel shield machine is actively controlled by releasing the pressure of the flexible buffer bag to realize the construction disturbance of the PBA tunnel, which changes the traditional passive control into active control, effectively controls the disturbance problem caused by different construction methods of the two tunnels, and increases the initiative of controlling the construction disturbance without reducing the effect of the passive control method.

[0023] (2) The disturbance caused by construction can be actively controlled in real time to a certain extent by the ground pressure control device, and the pressure of the flexible buffer bag can be adjusted in real time.

[0024] The technical solutions of the present application will be further described in detail below with reference to the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a close-range tunnel interval plan view of the PBA-shield construction method close-range construction disturbance active control method embodiment of the present application.

[0026] Figure 2 It is a close-range tunnel interval A-A' cross-sectional view of the PBA-shield construction method close-range construction disturbance active control method embodiment of the present application.

[0027] Figure 3 It is an interference active control method diagram of the PBA-shield construction method close-range construction disturbance active control method embodiment of the present application.

[0028] REFERENCE NUMERALS

[0029] 1, shield construction tunnel; 2, PBA construction tunnel; 3, pre-isolation hole; 4, pressure control device; 5, water outlet pipe; 6, water injection pipe; 7, flexible buffer bag; 8, cement mortar; 9, water; 10, tunnel middle soil layer; 11, construction site. DETAILED DESCRIPTION

[0030] EMBODIMENT

[0031] REFERENCE Figures 1-3 , Figure 1 It is a close-range tunnel interval plan view of two tunnels constructed by different construction methods, and the construction site 11 includes a PBA construction tunnel 2, a shield construction tunnel 1 and a middle soil layer 10 of the two tunnels, and the present application provides a PBA-shield construction method close-range construction disturbance active control method, which includes the following steps:

[0032] S1, before the construction of two tunnels, the flexible buffer bag 7 is pre-buried and pre-pressurized in the soil layer 10 between the tunnel 2 constructed by the PBA method and the tunnel 1 constructed by the shield method, and the pre-buried and pre-pressurized flexible buffer bag 7 specifically comprises the following steps:

[0033] S11, a rotary drilling rig with a drilling diameter of 300-400 mm is used to drill a pre-prepared isolation hole 3 at a certain distance in the soil layer between the two tunnels, and the distance and number of the pre-prepared isolation hole 3 are determined according to the length of the tunnel interval controlled by active construction interference.

[0034] S12, the flexible buffer bag 7 without water injection is placed in the predetermined position of the pre-prepared isolation hole 3, and the influence range of the flexible buffer bag 7 is 1d-1.5d, d being the horizontal diameter of the flexible buffer bag 7.

[0035] S13, the flexible buffer bag 7 is provided with a water injection pipe 6 and a water outlet pipe 5, and the water injection pipe 6 and the water outlet pipe 5 are connected with the pressure control device 4 on the ground.

[0036] S14, water 9 is injected into the flexible buffer bag 7 until the pressure of the flexible buffer bag 7 reaches the static soil pressure value of the relative position of the soil layer before excavation, the water injection is stopped, and the water injection pipe 6 is closed.

[0037] The static soil pressure value σ x is: σ x =K0γz, wherein γ is the unit weight of the soil layer, z is the embedding depth of the flexible buffer bag, K0 is the static soil pressure coefficient, is the internal friction angle of the soil body;

[0038] S15, the pre-prepared isolation hole 3 is completely filled with cement mortar 8 to a dense state, and the cement mortar 8 is completely hardened, and the pre-buried and pre-pressurized process of the flexible buffer bag 7 is completed.

[0039] S2, after the pre-buried and pre-pressurized flexible buffer bag 7 is completed, the tunnel construction is carried out, the tunnel 1 constructed by the PBA method is excavated first, at this time, the flexible buffer bag 7 does not need to be operated; the tunnel 2 constructed by the shield method is constructed, when the shield machine excavates to the active control interval where the construction interference is controlled by the flexible buffer bag 7, the pressure of the flexible buffer bag 7 is adjusted in real time according to the pressure sensor value and the soil pressure value of the tunnel face of the shield machine. When the advancing pressure of the shield machine is too large, the water 9 in the flexible buffer bag 7 is released to reduce the pressure of the flexible buffer bag 7 and reduce the lateral deformation of the soil body, so as to achieve the purpose of actively controlling the disturbance of the shield method construction to the tunnel constructed by the PBA method.

[0040] S3, after the tunnel construction is completed, the soil layer between the two tunnels is secondarily reinforced by the flexible buffer bag 7. Cement is injected into the flexible buffer bag 7 through the water injection pipe 6, and the water 9 is replaced out of the flexible buffer bag 7 due to the gravity of the cement, and the water 9 is discharged from the water outlet pipe 5. After the cement hardens, the secondary reinforcement is completed, and the safety risk problem caused by the soft interlayer due to the pre-embedded flexible buffer bag 7 after the construction of the two tunnels is completed is eliminated.

[0041] Therefore, the present application adopts the above-mentioned PBA-shield construction method for close-range construction disturbance active control method, pre-embeds the flexible buffer bag between the two tunnels constructed by different construction methods, and realizes the active control of the additional soil pressure generated by the shield tunnel shield machine on the construction disturbance of the PBA tunnel by releasing the pressure of the flexible buffer bag. The traditional construction disturbance passive control is changed into active control, the disturbance problem caused by the construction of the two tunnels by different construction methods is effectively controlled, the effect of the passive control method is not reduced, and the initiative of controlling the construction disturbance is increased.

[0042] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application and not to limit them, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that: the technical solutions of the present application can still be modified or replaced by the equivalent, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A method for actively controlling disturbances in close-range construction using a PBA-shield construction method, characterized in that: The following steps are involved: S1. Before the construction of the two tunnels, pre-buried and pre-pressurized flexible cushioning bags are placed in the soil between the two tunnels. The pre-buried and pre-pressurized flexible cushioning bags specifically include: S11. Drill isolation holes at regular intervals in the soil layer between the two tunnels; S12, placing the flexible cushioning bag that is not filled with water into a predetermined position of the pre-formed isolation hole; S13. The flexible cushioning bag is provided with a water injection pipe and a water outlet pipe, and the water injection pipe and the water outlet pipe are connected to the pressure control device on the ground; S14, injecting water into the flexible cushioning bag until the pressure of the flexible cushioning bag reaches the static earth pressure value of the relative position of the soil layer before excavation, stopping the water injection, and closing the water injection pipe; The static earth pressure value for: , , where is the soil layer density, z is the burial depth of the flexible cushioning bag, is the static earth pressure coefficient, is the internal friction angle of soil; S15. Fill the prefabricated isolation holes with cement mortar; S2. After the pre-embedded and pre-pressurized flexible cushioning bags are completed, tunnel construction will be carried out, with PBA tunnel excavation being carried out first, followed by shield tunnel construction; S3. After the tunnel construction is completed, the soil layer between the two tunnels is reinforced for the second time through flexible cushioning bags.

2. The method for actively controlling disturbances in close-range construction of a PBA-shield tunneling method according to claim 1, characterized in that: The step S2 of tunnel construction specifically includes: S21, first excavate the tunnel using the PBA method; S22. In the subsequent shield construction, when the shield machine excavates to the active control zone where the construction interference is controlled by the flexible buffer bag, the pressure of the flexible buffer bag is adjusted in real time according to the pressure sensor value and the soil pressure value applied by the shield machine on the tunnel face.

3. The method for actively controlling disturbances in close-range construction of a PBA-shield tunneling method according to claim 1, characterized in that: The secondary reinforcement method in step S3 is: injecting cement into the flexible cushioning bag through the water injection pipe to displace the water until the cement completely fills the flexible cushioning bag.

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