Tunnel arch frame structure and process for reinforcing soft soil layer by driving locking feet in advance

[0031] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent transformations made on the basis of the technical solutions of the present application fall within the protection scope of the present invention.

[0032] A kind of advanced locking feet to strengthen the soft soil tunnel arch structure. The locking foot conduit at the position of the arch foot of the steel arch of the upper step 1 is the ground leading locking guide 4, and the ground leading locking guide 4 is advanced from the ground 6 For the built-in locking foot conduit, the ground leading locking foot conduit 4 is connected to the steel arch of the upper step 1; the locking foot conduit at the arch foot position of the middle step 2 steel arch is the middle and lower step leading locking foot conduit 5, the middle and lower steps The leading foot guide tube 5 is a locking foot guide set in advance from the upper step 1. The middle and lower step leading locking foot guide 5 is connected to the steel arch of the middle step 2; the ground leading locking foot guide 4 and the middle and lower step leading locking foot The pipe 5 is grouted.

[0033] The above-mentioned construction process corresponding to the tunnel arch structure of the soft soil layer tunnel by setting the lock feet in advance includes the following steps:

[0034] (1) Design the position and setting angle of the ground leading lock foot conduit 4

[0035] According to the design drawings, the actual measured ground elevation, the distribution of ground pipelines, and the working conditions of underground tunnel excavation, the position and setting angle of the ground advanced locking foot conduit 4 are designed.

[0036] (2) 4 sets of advanced locking foot ducts on the ground

[0037] Set up according to the designed position and angle of the ground advanced locking foot conduit 4, first drill holes at the designed position, and then insert the ground advanced locking foot conduit 4. The spacing along the longitudinal direction of the tunnel is consistent with the design spacing of the steel arch in the tunnel. The hole arrangement area is set within the excavation and erection range of the steel arch to facilitate the effective connection of the steel arch after the excavation.

[0038] Preferably, the angle between the laying angle of the ground advance locking foot conduit 4 and the vertical direction is preferably controlled at 10-40°, and the laying length is better than 4-6 meters at the steel arch node of the upper middle step 2.

[0039] According to the distribution situation, such as the ground road structure layer is geologically hard, in the ground road structure layer, because the structure layer is relatively stable, the hole will not collapse after the hole is formed, and the hole can be left. The ground advance locking tube 4 is actually arranged within the tunnel. tube.

[0040] As a preferred solution, because the buried depth of the tunnel is generally about 10 meters, plus the anchoring depth of the lock foot 4-6 meters and the excavation depth of the upper step 1, and then subtract the empty section, the length of the ground leading lock foot conduit 4 is generally controlled to 14 -16 meters or so is better.

[0041] According to the stratum and surrounding environment, the quantity, diameter, length, etc. of the ground leading foot pipe 4 can be appropriately increased. The ground leading foot pipe 4 can be selected from steel pipes with a diameter of 79mm or 108mm.

[0042] (3) Grouting for the ground leading lock foot conduit 4

[0043] After the ground advanced locking tube 4 is set up, the cement single liquid slurry is injected, and the soil of the vault is reinforced through the ground advanced locking tube 4 at the same time, which can also play the role of advanced support for the tunnel vault, reducing To reduce the lateral pressure of the tunnel vault.

[0044] (4) Excavation of stairs 1 in the tunnel

[0045] The ground advanced locking foot conduit 4 built on the ground 6 is mainly used to reinforce the upper step 1 steel arch. In order to ensure construction safety, reduce settlement and facilitate the construction of the lock foot, minimize the excavation height of the upper step 1 of the tunnel, and control the excavation height of the upper step 1 to meet the normal construction work space. Preferably, the excavation height of the upper step 1 should be controlled within 3-4 meters. This height can meet the requirements of manual cooperation with small drilling rigs and conventional excavation equipment construction.

[0046] The upper step 1 in the tunnel is exposed during the excavation of the above-mentioned advanced ground locking guide tube 4, which is slightly adjusted according to the position of the ground leading locking guide tube 4 and the setting position of the steel arch, and the ring hoop is used to pass through the steel bar. The welding method effectively connects the steel arch frame of the upper step 1 and the ground advanced locking foot pipe 4 to ensure that the steel arch frame is fixed by the ground advanced locking foot pipe 4.

[0047] (5) Set up the advanced locking foot catheter 5 on the upper step 1 in the middle and lower steps

[0048] After the upper step 1 in the tunnel is constructed for a certain length, after the working surface is formed, the working space of the upper step 1 is used to set the middle and lower step advance locking foot conduit 5 at the middle and lower step node in the tunnel. The arch toe of the lower and lower steps of the steel arch frame on the left and right sides bear the weight of the entire tunnel, which is particularly critical for controlling the overall settlement of the tunnel. According to the excavation height of the upper step 1 and the steel arch erection spacing, the middle and lower step joint steel arch foot position of the middle and lower step joint steel arch foot position of the middle and lower step advanced locking foot conduit 5 arrangement spacing, laying length and angle are calculated.

[0049] When setting the lock feet of the middle and lower steps in advance from the upper step 1, the remaining excavation height of the middle and lower steps is calculated according to the excavation height of the upper step 1. If the ground is stable within this height, the hole collapse will not occur after the hole is formed , Directly use the hole drilling machine to make the hole, and place the middle and lower step advanced locking foot conduit 5 in the design position of the middle and lower step arch angle; if the formation is poor and there is a hole collapse phenomenon, use the full protection barrel to drill and place the hole down After the middle and lower steps advance the locking foot tube 5 to the design position, lift the protective tube.

[0050] Preferably, the angle between the setting angle of the middle and lower step leading locking foot conduit 5 and the vertical direction is controlled to be 10-40°.

[0051] Because of the large operating space, the working time can be prolonged, and the setting depth of the middle and lower steps of the leading locking foot catheter 5 can be lengthened. Preferably, the anchoring length of the middle and lower steps of the leading locking foot catheter 5 is 4-6 meters.

[0052] According to the stratum and surrounding environment, the number, diameter, length, etc. of the middle and lower step leading locking foot conduits 5 can be appropriately increased, and steel pipes with a diameter of 79mm or 108mm can be selected as the tunnel supporting steel arch leading locking foot conduits.

[0053] In this way, the anchoring force between the locking foot and the soil is increased from the anchoring length and diameter of the leading locking foot conduit, and the settlement resistance of the steel arch frame connected with it is improved.

[0054] (6) The middle and lower steps are grouted in advance of the locking foot conduit 5

[0055] After the erection is completed, the middle and lower steps are injected with cement single liquid slurry in advance of the locking foot conduit 5, and the invert soil is reinforced by grouting through the leading locking pipe, which can effectively increase the foundation bearing capacity of the tunnel invert soil and reduce Tunnel settlement.

[0056] (7) Excavation of middle step 2 in the tunnel

[0057] During the excavation of the middle step 2 in the tunnel, the above-mentioned advanced middle and lower step locking foot guide tube 5 was exposed. According to the position of the middle and lower step leading locking foot guide 5 and the setting position of the steel arch, it should be adjusted slightly, and the ring hoop is adopted. The steel arch of the middle step 2 is effectively connected to the leading locking foot conduit 5 of the middle and lower steps through the method of welding the steel bars, and the steel arch is secured by the leading locking foot conduit 5 of the middle and lower steps.

[0058] (8) Excavate the lower step 3 to complete the initial support and closure into a ring.

[0059] The above-mentioned embodiments are only one of the more preferred specific embodiments of the present invention, and the usual changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included in the protection scope of the present invention.