Double-side-wall composite cross method construction method for large-span tunnel under complex geological condition

A complex geological condition and composite cross technology, applied in tunnels, tunnel linings, underground chambers, etc., can solve problems such as easy deformation of support structures and unsuitable control of vault settlement, and achieve easy construction quality assurance, convenient construction, and structural integrity. Excellent effect

Inactive Publication Date: 2018-09-04

CHINA RAILWAY ERYUAN ENG GRP CO LTD

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AI-Extracted Technical Summary

Problems solved by technology

[0005] The technical problem to be solved by the present invention is to provide a construction method of double-side wall compound crossing method for large-span tunnels under complex geological conditions, so as to overcome the unsuitab...

Method used

With reference to Fig. 1, anchor rod 20 is set at the steel frame joint of the arch, and when the temporary support of the arch is removed, the sinking of the vault can be effectively controlled. The steel frame concrete foundation of the left pilot tunnel III and the steel frame concrete foundation VI of the right pilot tunnel are only used as the bearing foundation of the primary support. On the premise of ensuring the stability of the primary support system of the arch wall, the secondary lining XV of the arch wall is still Integral formwork trolley can be used for construction, the process is simple, the integrity of the secondary lining is ensured, the waterproof effect is good, and the construction quality is controllable. With partial excavation, each section can realize large-scale mechanized operations and rapid construction.

With reference to Fig....

Abstract

The invention provides a double-side-wall composite cross method construction method for a large-span tunnel under the complex geological condition. The double-side-wall composite cross method construction method is used for solving the technical problems that during construction of a soft rock large-span tunnel, arch crown settlement is not easy to control and a support structure is prone to deforming, optimizing structural force, improving construction convenience and determining construction safety. According to the double-side-wall composite cross method construction method, pilot tunnelson the two sides are constructed firstly, and primary support side wall foundations are constructed in the pilot tunnels to serve as a bearing foundation of an upper primary support system, so that the problems that during construction of the soft rock large-span tunnel, arch crown settlement is not easy to control and the support structure is prone to deforming are solved; bases only serve as thebearing foundation of primary support, under the premise that the stability of the arch wall primary support system is guaranteed, an arch wall secondary lining can still be constructed through an integral formwork trolley, the technique is simple and convenient, the integrity of the secondary lining is guaranteed, the waterproof effect is good, and the construction quality is controllable; and the pilot tunnels on the two sides adopt the excavated section of an arc-shaped arch crown, compared with conventional pilot tunnels constructed through a double-side-wall heading method, the structureforce is more excellent, construction is convenient, and the construction quality of the support system is easy to ensure.

Application Domain

Underground chambersTunnel lining +1

Technology Topic

ClerestorySupport system +2

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Experimental program(1)

Example Embodiment

[0030] The present invention will be further described below in conjunction with the drawings and embodiments.

[0031] Refer to Figure 1 to Figure 7 , The composite cross method construction method of double side walls of a large-span tunnel under complex geological conditions of the present invention includes the following steps:

[0032] (1) Excavate the upper step 1 and the lower step 2 of the left pilot tunnel step by step. Before excavation, apply the corresponding advance support, and immediately apply the corresponding initial support and temporary support after the excavation;

[0033] ⑵Pour the steel frame concrete base Ⅲ of the left pilot tunnel;

[0034] (3) Excavate step by step the upper step 4 of the right pilot tunnel, and the lower step 5 of the right pilot tunnel. Before excavation, apply the corresponding advance support, and immediately apply the corresponding initial support and temporary support after the excavation;

[0035] ⑷Steel frame concrete base of the pilot hole on the right side Ⅵ;

[0036] ⑸Excavate the upper step 7 on the left side of the arch, apply the corresponding advanced support before excavation, apply the corresponding initial support and temporary support immediately after the excavation, and apply it to the surrounding rock at the top of the corresponding initial support The anchor rod 20 is anchored, and the other end of the anchor rod 20 is firmly connected with the steel arch frame;

[0037] ⑹The lower step 8 on the left side of the excavation arch shall be provided with corresponding advance support before excavation, and the corresponding initial support and temporary support shall be implemented immediately after excavation. The lower end of the corresponding initial support shall be connected to the left pilot tunnel steel The steel frame connection reserved in the concrete base Ⅲ shall be removed, and the support of the arch in the left pilot tunnel shall be removed;

[0038] ⑺ Excavate the upper step 9 on the right side of the arch, apply the corresponding advanced support before excavation, apply the corresponding initial support and temporary support immediately after the excavation, and apply it to the surrounding rock at the top of the corresponding initial support The anchor rod 20 is anchored, and the other end of the anchor rod 20 is firmly connected with the steel arch frame;

[0039] ⑻The lower step 10 on the right side of the excavation arch should be provided with corresponding advance support before excavation, and the corresponding initial support and temporary support should be implemented immediately after excavation. The lower end of the corresponding initial support and the right pilot tunnel steel The steel frame connection reserved in the concrete base VI shall be removed, and the arch support in the right pilot tunnel shall be removed;

[0040] ⑼Excavate the upper layer 11 of the lower core soil and the lower layer 12 of the lower core soil step by step, and immediately implement the initial support of the invert after the excavation is completed;

[0041] ⑽Pour the invert arch secondary lining XIII concrete in sections, and pour the invert arch filling XIV concrete after reaching the design strength;

[0042] ⑾ After the inverted arch filling layer XIV reaches the design strength, the arch wall is poured with XV concrete for the second time using a formwork trolley.

[0043] Refer to figure 1 , The surrounding rock of the soft (quality) rock formation is weak, and the force on the side wall of the large-span tunnel is concentrated, firstly construct the pilot tunnels on both sides, and construct the left pilot tunnel steel frame concrete base III and the right pilot tunnel steel in the pilot tunnel The concrete foundation VI is used as the bearing foundation of the upper initial support system to solve the problem of uncontrollable vault settlement and easy deformation of the supporting structure during the construction of large-span soft rock tunnels. The pilot tunnel on both sides adopts the excavation section with arc-shaped arch roof. Compared with the conventional double-side pilot tunnel method, the structure is more stressed, the construction is convenient, and the construction quality of the supporting system is easy to guarantee.

[0044] Refer to figure 1 , The anchor rod 20 is set at the joint of the arch steel frame, which can effectively control the arch sinking when the temporary support of the arch is removed. The steel frame concrete base Ⅲ of the left pilot tunnel and the steel frame concrete foundation Ⅵ of the right pilot tunnel are only used as the bearing foundation for the initial support. Under the premise of ensuring the stability of the initial support system of the arch wall, the secondary lining XV of the arch wall is still Integral formwork trolley can be used for construction, the process is simple, to ensure the integrity of the secondary lining, the waterproof effect is good, and the construction quality is controllable. Using branch excavation, each section can realize large-scale mechanized operation and rapid construction.

[0045] The applicant successfully applied the technical solution of this application to the design and construction of the new Chengdu-Lanzhou Railway Shiziyuan Tunnel. The tunnel is located in the section between Anxian and Gaochuan with a single slope on the line. The left line pull-through tunnel has a total length of 14.069km. , 10.654km at the inlet end is a single-hole double track (combined repair), and 3.415km at the outlet end is a double-hole single track (sub-repair). Among them, the 150m section from D3K87+200 to D3K87+350 is the transitional section for combined, sub-repair, and the excavation span is 23m at the boundary of D3K87+350.

[0046] The topography of this section is in the section of steep slope change from the secondary alluvial terrace to the steep ditch wall. The buried depth is 130-150m. It is located in the Wangjiaping 1# fault fracture zone. The rock quality is weak and the groundwater is weakly developed; the ground stress level is high. , Mainly tectonic stress, the average maximum horizontal principal stress is 16.26MPa, and the average vertical stress is 11.78MPa. After the construction of the adjacent sub-repair tunnel, deformation and cracking occurred and the secondary lining structure was destroyed. The original design of the large-span section uses the traditional double-side-wall pilot method (refer to Picture 8 ) Construction, the construction method has the following problems:

[0047] 1. In the weak surrounding rock section, the bearing capacity of the surrounding rock is weak, and the bearing capacity of the side wall foot is insufficient, and the upper surrounding rock will sink, causing damage to the supporting structure or even collapse. This construction method cannot guarantee structural safety.

[0048] 2. Restricted by the step-by-step excavation outline, some procedures do not meet the requirements of large-scale machinery construction.

[0049] That is to say, if the engineering example adopts the traditional double-side-wall piloting method, the safety of the supporting structure cannot be guaranteed, and the foundation bearing capacity of the side wall supporting structure is insufficient, which will cause the upper surrounding rock to sink or even collapse. The processing is difficult and costly. The construction method of the present invention effectively solves the problem of structural safety. The steel frame concrete in the side hole expands the foundation, which effectively solves the problem of insufficient bearing capacity of the side wall. Each step of the method is suitable for large-scale mechanical construction, the construction organization is convenient, and the project investment can be saved by 30%.

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Double-side-wall composite cross method construction method for large-span tunnel under complex geological condition

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Problems solved by technology

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Abstract

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