Tunnel three-step to two-step construction method

Abstract

The present application relates to single-hole four-lane tunnel construction technical field, and disclose a kind of tunnel three-step to two-step construction method, the method comprises the following steps: excavating upper step II;Following middle step III and lower step III construction;Upper step II is excavated according to two-step method, and blast hole is inserted into interface floor at an angle;Upper step II excavation height is lifted gradually, and upper step II arch foot is lengthened gradually;Arch foot is reserved with the surrounding rock surface of predetermined width, to avoid arch foot suspended;Excavate lower step II: lower step II single-side excavation;Excavate using two-step method;When drilling upper step I, do not excavate with the thickness of reserved surrounding rock on both sides of arch foot, and support in time;Lower step I follows step interface line position, and excavate according to normal two-step method when excavating;The present application effectively solves the problem that large-section tunnel construction method disturbs each other, so that the problem of serious delay in construction period is solved.

Description

Technical Field

[0001] This invention belongs to the field of single-bore four-lane tunnel construction technology, specifically a method for tunnel construction from three-stage to two-stage. Background Technology

[0002] Currently, the well-known method of transitioning from a three-stage to a two-stage excavation for highway tunnels is characterized by a wide range of disturbances. This is especially true for large-section tunnels undergoing this method change, where the lower bench's descent causes significant disturbance to the tunnel face, resulting in prolonged downtime and serious delays in construction progress, impacting the project schedule. There is currently no effective method to address this issue without causing prolonged downtime at the tunnel face during the three-stage to two-stage tunnel construction transition.

[0003] Therefore, in view of the above situation, there is an urgent need to provide a tunnel construction method that transitions from a three-stage to a two-stage approach, in order to overcome the shortcomings in current practical applications. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, this invention provides a method for tunnel construction that transitions from a three-stage to a two-stage approach, effectively solving the problem of significant mutual disturbance between different construction methods in large-section tunnels, which leads to serious delays in the construction period.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for constructing a tunnel from a three-stage to a two-stage approach, the method comprising the following steps:

[0006] Step 1: Excavate the upper bench II;

[0007] Step 1.1: Follow up on the construction of the middle step III and the lower step III;

[0008] Step 1.2: The upper bench II is excavated using the two-bench method, with blast holes inserted obliquely into the dividing bottom plate;

[0009] Step 1.3: The excavation height of Upper Bench II is increased frame by frame, and the arch foot of Upper Bench II is lengthened frame by frame;

[0010] Step 1.4: Reserve a predetermined width of surrounding rock surface at the arch foot to prevent the arch foot from being suspended in the air;

[0011] Step 2: Excavation of the lower bench II:

[0012] Step 2.1: Single-sided excavation of the lower bench II;

[0013] Step 2.2: Excavation using the two-stage method;

[0014] Step 2.3: When drilling on the upper step I, leave a predetermined thickness of surrounding rock on both sides of the arch foot without excavating, and provide timely support;

[0015] Step 2.4: Follow the step boundary line of the lower step I and excavate according to the normal two-step construction method.

[0016] Preferably, in step 1.2, the length of the upper step II is controlled to be one hole diameter.

[0017] Preferably, in step 1.3, the arch foot of the upper step II is lengthened and lowered to the step boundary line.

[0018] Preferably, in step 2.1, the single-sided excavation of the lower bench II causes the lower bench II arch frame to be shortened one by one and follow the boundary line between the upper and lower benches.

[0019] Preferably, in step 2.2, the two-step excavation method includes two parts: upper step II and lower step II.

[0020] Preferably, in step 2.3, the excavation is carried out sequentially from the upper step I to the lower step I.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] By sequentially increasing the excavation height of the upper step II, shortening the height of the lower step II by 30cm, 50cm, and 80cm respectively below the original upper-middle step boundary; controlling the step length by inserting blast holes at an angle into the bottom slab and reserving a certain thickness of surrounding rock on both sides of the arch foot; and ensuring the water accumulation on the face side of the upper step II due to reverse excavation, water pumps are installed and used to prevent water accumulation in the upper step II; after the upper step I is excavated and supported, a certain thickness of surrounding rock is reserved on the arch foot side during excavation to support the suspension of the upper step arch frame, so that the lower step II arch frame can be integrated with the upper and lower step I arch frame support once it reaches the bottom; this method can reduce the disturbance to the face during the conversion from three steps to two steps and avoid the impact of construction method conversion. This method reduces downtime at the tunnel face, saving production costs and construction time; it also facilitates smoother coordination of construction procedures; by reserving a certain thickness of surrounding rock on both sides of the arch foot of the upper bench I during excavation, the surrounding rock and the upper bench II arch frame become an integrated support system, redistributing the stress in the surrounding rock. When excavating, this reduces the suspension of the upper bench II arch frame, avoiding deformation of the initial support system caused by disturbance, thus accelerating the construction progress at the tunnel face; the excavation of the lower bench II adopts normal weak blasting combined with mechanical methods, promptly following up with the upper bench II arch frame support system to become integrated, further preventing cracking of the already structured support system; it effectively solves the problem of significant mutual disturbance in large-section tunnel construction methods, which causes serious delays in the construction period. Attached Figure Description

[0023] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0024] In the attached diagram:

[0025] Figure 1 This is a technical procedure diagram for the three-stage tunnel construction method; where 1 represents the advanced support of the upper stage arch, 2 represents the upper stage, 3 represents the middle stage, 4 represents the lower stage, Ⅲ represents the initial support of the upper stage, Ⅴ represents the initial support of the middle stage, Ⅵ represents the initial support of the lower stage, Ⅷ represents the waterproofing construction and pouring of the invert arch, and Ⅸ represents the lining pouring construction.

[0026] Figure 2 This is a schematic diagram of the construction steps for a tunnel three-stage to two-stage construction method provided in an embodiment of the present invention.

[0027] Figure 3 This invention provides a plan view of the construction process for converting a three-stage tunnel construction method to a two-stage method, as shown in the embodiment of the invention. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0029] Please see Figures 1-3 The present invention provides a method for tunnel construction transitioning from a three-stage to a two-stage approach, the method comprising the following steps:

[0030] Step 1: Excavate the upper bench II;

[0031] Step 1.1: Follow up on the construction of the middle step III and the lower step III;

[0032] Step 1.2: The upper bench II is excavated using the two-bench method, with blast holes inserted obliquely into the dividing bottom plate;

[0033] Step 1.3: The excavation height of Upper Bench II is increased frame by frame, and the arch foot of Upper Bench II is lengthened frame by frame;

[0034] Step 1.4: Reserve a predetermined width of surrounding rock surface at the arch foot to prevent the arch foot from being suspended in the air;

[0035] Step 2: Excavation of the lower bench II:

[0036] Step 2.1: Single-sided excavation of the lower bench II;

[0037] Step 2.2: Excavation using the two-stage method;

[0038] Step 2.3: Excavate in sequence from upper step I to lower step I. When drilling for upper step I, leave a predetermined thickness of surrounding rock on both sides of the arch foot and do not excavate. Provide support in a timely manner.

[0039] Step 2.4: Follow the step boundary line of the lower step I and excavate according to the normal two-step construction method.

[0040] In this embodiment of the invention, the height of the upper step II is increased sequentially, and the height of the lower step II is shortened sequentially by 30cm, 50cm, and 80cm below the original upper-middle step dividing line, respectively. By inserting blast holes at an angle into the bottom plate and reserving a certain thickness of surrounding rock on both sides of the arch foot, the step length is controlled. Since the upper step II is excavated in reverse on the face side, water accumulation may occur during construction, and water pumps are installed promptly to prevent water accumulation in the upper step II. After the upper step I is excavated and supported, a certain thickness of surrounding rock is reserved on the arch foot side during excavation to support the suspension of the upper step arch frame. Once the lower step II arch frame is lowered, the upper and lower step I arch frame supports become a single unit. This method can reduce the disturbance to the face during the transition from three steps to two steps, avoiding... The change in construction method reduces downtime at the tunnel face, thus saving production costs and shortening the construction period. It also facilitates smoother coordination of construction procedures. By reserving a certain thickness of surrounding rock on both sides of the arch foot of the upper bench I during excavation, the surrounding rock and the upper bench II arch frame become an integrated support system, redistributing the stress in the surrounding rock. This reduces the suspension of the upper bench II arch frame during excavation, preventing deformation of the initial support system and accelerating the construction progress at the tunnel face. The excavation of the lower bench II uses normal weak blasting combined with mechanical methods, promptly integrating with the upper bench II arch frame support system to further prevent cracking of the existing support system structure. This effectively solves the problem of significant mutual disturbance between different construction methods in large-section tunnels, which severely delays the construction period.

[0041] In one embodiment of the present invention, please refer to Figure 2 and Figure 3 In step 1.2, the length of the upper step II is controlled to be one times the diameter of the hole.

[0042] In one embodiment of the present invention, please refer to Figure 2 and Figure 3 In step 1.3, the arch foot of the upper step II is lengthened and lowered to the step dividing line.

[0043] In one embodiment of the present invention, please refer to Figure 2 and Figure 3 In step 2.1, the single-sided excavation of the lower bench II causes the lower bench II arch frame to be shortened one by one and follow the boundary line between the upper and lower benches.

[0044] In one embodiment of the present invention, please refer to Figure 2 and Figure 3 In step 2.2, the two-step excavation method includes two parts: upper step II and lower step II.

[0045] In one embodiment of the present invention, please refer to Figure 2 and Figure 3 In step 2.3, excavation is carried out sequentially from upper step I to lower step I.

[0046] Working principle: First, the upper bench face is directly excavated using the two-bench method and supported in a timely manner. By reserving a certain thickness of surrounding rock on the arch foot side of the upper bench I, the problem of the arch frame arch foot being suspended is reduced. The excavation height of the upper bench II is increased frame by frame. The lower bench II is followed up in a timely manner, thereby ensuring the safety of the tunnel structure.

[0047] By sequentially increasing the excavation height of the upper step II, shortening the height of the lower step II by 30cm, 50cm, and 80cm respectively below the original upper-middle step boundary; controlling the step length by inserting blast holes at an angle into the bottom slab and reserving a certain thickness of surrounding rock on both sides of the arch foot; and ensuring the water accumulation on the face side of the upper step II due to reverse excavation, water pumps are installed and used to prevent water accumulation in the upper step II; after the upper step I is excavated and supported, a certain thickness of surrounding rock is reserved on the arch foot side during excavation to support the suspension of the upper step arch frame, so that the lower step II arch frame can be integrated with the upper and lower step I arch frame support once it reaches the bottom; this method can reduce the disturbance to the face during the conversion from three steps to two steps and avoid the impact of construction method conversion. This method reduces downtime at the tunnel face, saving production costs and construction time; it also facilitates smoother coordination of construction procedures; by reserving a certain thickness of surrounding rock on both sides of the arch foot of the upper bench I during excavation, the surrounding rock and the upper bench II arch frame become an integrated support system, redistributing the stress in the surrounding rock. When excavating, this reduces the suspension of the upper bench II arch frame, avoiding deformation of the initial support system caused by disturbance, thus accelerating the construction progress at the tunnel face; the excavation of the lower bench II adopts normal weak blasting combined with mechanical methods, promptly following up with the upper bench II arch frame support system to become integrated, further preventing cracking of the already structured support system; it effectively solves the problem of significant mutual disturbance in large-section tunnel construction methods, which causes serious delays in the construction period.

[0048] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0049] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for constructing a tunnel from a three-stage to a two-stage approach, characterized in that, The method includes the following steps: Step 1: Excavate the upper bench II; Step 1.1: Follow up on the construction of the middle step III and the lower step III; Step 1.2: The upper bench II is excavated using the two-bench method, with blast holes inserted obliquely into the dividing bottom plate; Step 1.3: The excavation height of Upper Bench II is increased frame by frame, and the arch foot of Upper Bench II is lengthened frame by frame; Step 1.4: Reserve a predetermined width of surrounding rock surface at the arch foot to prevent the arch foot from being suspended in the air; Step 2: Excavation of the lower bench II: Step 2.1: Single-sided excavation of the lower bench II; Step 2.2: Excavation is carried out using the two-step method, which includes an upper step I and a lower step I. Step 2.3: When drilling on the upper step I, leave a predetermined thickness of surrounding rock on both sides of the arch foot without excavating, and provide timely support; Step 2.4: Follow the step boundary line of the lower step I and excavate according to the normal two-step construction method.

2. The tunnel construction method for transitioning from a three-stage to a two-stage approach according to claim 1, characterized in that, In step 1.2, the length of the upper step II is controlled to be one hole diameter.

3. The tunnel three-stage to two-stage construction method according to claim 1, characterized in that, In step 1.3, the arch foot of the upper step II is lengthened and lowered to the step dividing line.

4. The tunnel construction method for transitioning from a three-stage to a two-stage approach according to claim 1, characterized in that, In step 2.1, the single-sided excavation of the lower bench II causes the lower bench II arch frame to be shortened one by one and follow the boundary line between the upper and lower benches.

5. The tunnel three-stage to two-stage construction method according to claim 1, characterized in that, In step 2.3, excavation is carried out sequentially from upper step I to lower step I.

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