A micro-step based improved tunnel excavation method for small and medium cross sections

Abstract

The application belongs to the technical field of building construction, and particularly discloses a micro-step improved tunnel excavation method for medium and small sections, which comprises the following steps: tunnel upper step excavation is performed for 3-5 m, a ramp is formed by lower step slope brushing, and personnel and equipment are allowed to enter the upper step area for construction operation; a left (right) half temporary support device is removed, drilling and blasting or mechanical excavation is performed on the left (right) half part of rock and soil of the lower step according to the surrounding rock condition; left (right) half initial spraying, installation of a two-unit steel arch support, anchor rod, steel mesh and concrete spraying are performed to complete the initial support. The lower step of the traditional micro-step is excavated in the form of a ramp, and a variable-height steel arch support temporary support device is used for support, so that the limitation of the micro-step method in the construction of the upper step operation by using the cantilever type excavation trolley is solved, and problems such as difficult upper step excavation and slag cleaning, serious over-excavation, and the need for a large amount of manual finishing due to under-excavation are solved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of building construction, and discloses a small-to-medium section tunnel excavation method based on micro-step improvement. BACKGROUND

[0002] With the development of infrastructure construction, traditional highway engineering and railway engineering have been increasingly saturated, and new infrastructure projects such as logistics tunnels and water diversion tunnels are rapidly emerging. The most characteristic of such tunnels is that the section is small, the slope is large, and the tunnel is long and narrow. Even for highway and railway tunnels, when long and large tunnels are constructed, small section tunnels such as inclined shafts and ventilation branch holes need to be set as auxiliary projects. The biggest difficulty of small section tunnels is that large complete mechanical equipment cannot be used for construction, and the construction efficiency is generally low. The present application provides a new small-to-medium section tunnel excavation method, which has far-reaching significance for the vigorous development of new infrastructure. SUMMARY

[0003] In view of the above problems, the application provides a small-to-medium section tunnel excavation method based on micro-step improvement.

[0004] The specific technical scheme is as follows: a small-to-medium section tunnel excavation method based on micro-step improvement, characterized by comprising the following steps:

[0005] S1: excavating 3-5 m of the upper step (① part) of the tunnel, brushing the slope of the lower step (② part) to form a ramp, and satisfying the personnel and equipment entering the upper step area for construction work; step S1 specifically comprises the following steps:

[0006] S1-1: advance support;

[0007] S1-2: according to the surrounding rock condition, drilling and blasting or mechanically excavating the upper step (① part) and brushing the slope of the lower step (② part);

[0008] S1-3: initially spraying 5 cm of concrete on the upper step (① part);

[0009] S1-4: installing a unit of steel arch, and temporarily supporting the steel frame in the slope area by using a variable-height arch temporary support device for the steel arch in the slope area to prevent the unit of arch from being suspended;

[0010] S1-5: applying steel mesh and anchor rods, and spraying concrete to complete the initial support of the upper step (① part);

[0011] S2: removing the left (right) half of the temporary support device, and according to the surrounding rock condition, drilling and blasting or mechanically excavating the left (right) half of the rock and soil of the lower step;

[0012] S3: initially spraying, installing a unit of steel arch, anchor rods, steel mesh and spraying concrete to complete the initial support of the left (right) half;

[0013] S4: remove the right (left) half of the temporary support device, and drill and blast or mechanically excavate the right (left) half of the rock-soil of the lower step according to the surrounding rock condition;

[0014] S5: right (left) half of the initial spray, installation of two-unit steel arch, anchor rod, steel mesh and spray concrete to complete the initial support.

[0015] Further, the support device of steps S1-4 can adjust the height of the distance between the slope and the arch foot.

[0016] Further, the slope of the lower step (part ②) of step S1 is 30°-45°.

[0017] The beneficial effects of the present application are:

[0018] The present scheme excavates the lower step of the traditional micro-step in the form of a ramp, and a variable-height arch temporary support device is used for the steel arch of the ramp area to temporarily support the area where the lower steel arch cannot be installed to prevent suspension, solving the limitations of the micro-step method in using the cantilever excavating car to construct the upper step, including the limited upper step footage caused by the limited length of the cantilever, the low efficiency problem caused by the operation platform; In particular, it solves the problems of difficult upper step excavation and slag removal, serious over-excavation, and the need for a large amount of manual finishing caused by the excavator being located at the bottom of the tunnel, and the driver being unable to see the actual situation of the upper step during the traditional micro-step excavation process. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 Existing micro-step excavation diagram;

[0020] Figure 2 It is a kind of excavation diagram of improved micro-step based small cross section tunnel excavation method;

[0021] Figure 3 Existing micro-step method stand support diagram;

[0022] Figure 4 It is a kind of stand support diagram of improved micro-step based small cross section tunnel excavation method;

[0023] Figure 5 It is a kind of different span small cross section tunnel excavation diagram of improved micro-step based small cross section tunnel excavation method;

[0024] Figure 6 It is a kind of variable height arch temporary support device diagram;

[0025] In the figure: ① part - upper step; ② part - lower step (or left lower step); ③ part - right lower step. EMBODIMENT

[0026] In order to make the technical problems and technical solutions solved by the present application clearer, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0027] As shown in Figure 2 , 4 The present embodiment discloses a micro-step improved small and medium section tunnel excavation method, which comprises the following steps:

[0028] S1: excavating 3-5m of the upper step (① part) of the tunnel, brushing the slope of the lower step (② part) to form a ramp, and satisfying the personnel, materials and equipment entering the upper step area for construction operation, thereby avoiding the problems of space congestion of the working face, difficulty in moving materials and equipment along the jumbo, and high labor intensity caused by jumbo operation; step S1 specifically comprises the following steps:

[0029] S1-1: pre-supporting, using advanced small pipe grouting or advanced mortar anchor rod to pre-support the rock mass above the excavation face according to the design;

[0030] S1-2: drilling and blasting or mechanically excavating the upper step (① part) according to the surrounding rock condition, and brushing out the inclined lower step (② part);

[0031] S1-3: according to the design, initially spraying 5cm of concrete on the upper step (① part);

[0032] S1-4: installing a unit of steel arch, and using a variable-height arch temporary support device for the steel arch in the inclined area to temporarily support the steel arch in the inclined area to prevent the unit arch from being suspended;

[0033] S1-5: applying steel mesh and anchor rod, and spraying concrete to complete the initial support of the upper step (① part);

[0034] S2: removing the left (right) half of the temporary support device, and drilling and blasting or mechanically excavating the left (right) half of the rock soil of the lower step according to the surrounding rock condition;

[0035] S3: initially spraying, installing a second unit of steel arch, anchor rod, steel mesh and spraying concrete to complete the initial support of the left (right) half;

[0036] S4: removing the right (left) half of the temporary support device, and drilling and blasting or mechanically excavating the right (left) half of the rock soil of the lower step according to the surrounding rock condition;

[0037] S5: initially spraying, installing a second unit of steel arch, anchor rod, steel mesh and spraying concrete to complete the initial support of the right (left) half.

[0038] It needs to be further explained that the support device described in step S1-4 can adapt to the distance adjustment height between the slope and the arch foot, such as Figure 4 , two-unit arch frame is a temporary support device of a variable height arch frame, which connects the one-unit arch frame and the variable height arch frame to the same vertical plane through the connecting steel plate, and adjusts the height of the variable height arch frame to meet the support requirements of different parts of the slope; while the existing micro-step method of vertical support (such as Figure 3 ) strictly follows the upper and lower bench unit vertical support, and the step distance is synchronized.

[0039] As shown in Figure 1 , 2 , the slope of the lower step (② part) in step S1 is 30°-45°, which can meet the walking and standing of conventional construction machinery such as excavators and loaders, while the lower step of the existing micro-step is 90° straight up or 45°-75° steep, and cannot be used as a construction equipment channel or work platform.

[0040] As shown in Figure 5 , the above small and medium cross-section tunnel excavation method is suitable for tunnels of different spans. For small-span tunnel excavation parts, it includes the upper step (① part), the left lower step (② part), and the right lower step (③ part); for large-span tunnel excavation parts, it includes the upper step (① part), the left lower step (② part), the slope, and the right lower step (③ part).

[0041] The invention has been described in detail through specific and preferred embodiments, but those skilled in the art should understand that the invention is not limited to the above-mentioned embodiments, and any modifications, equivalent replacements, etc. made within the spirit and principles of the invention should be included in the protection scope of the invention.

Claims

1. A method for excavating a small-to-medium cross-section tunnel based on a micro-step improvement, characterized in that, It comprises the following steps: S1: Excavating the upper step 3-5m and brushing the slope of the lower step to form a ramp, which meets the requirements of personnel and equipment entering the upper step area for construction work; step S1 specifically comprises the following steps: S1-1: Advanced support; S1-2: According to the surrounding rock conditions, drill and blast or mechanical excavation of the upper step, and brush the slope of the lower step; S1-3: Initial spraying of 5cm concrete on the upper step; S1-4: Install a unit of steel arch, for the steel arch in the slope area, a variable height arch temporary support device is used to temporarily support the steel arch in the slope area to prevent the unit steel arch from being suspended; S1-5: Apply steel mesh and anchor rod, and spray concrete to complete the initial support of the upper step; S2: Remove the left or right half of the temporary support device, and according to the surrounding rock conditions, drill and blast or mechanically excavate the left or right half of the rock and soil of the lower step; S3: Left or right half initial spraying, installation of two units of steel arch, anchor rod, steel mesh and spraying of concrete to complete the initial support; S4: Remove the right or left half of the temporary support device, and according to the surrounding rock conditions, drill and blast or mechanically excavate the right or left half of the rock and soil of the lower step; S5: Right or left half initial spraying, installation of two units of steel arch, anchor rod, steel mesh and spraying of concrete to complete the initial support.

2. The improved micro-step based tunnel excavation method for small and medium cross-sections according to claim 1, characterized in that, The support device of step S1-4 can adjust the height according to the distance between the ramp and the arch foot.

3. The improved micro-step based tunnel excavation method for small and medium cross-sections according to claim 1, characterized in that, The slope of the lower step of step S1 is 30°-45°.

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