CN202673299U - Double-layer mold constructing composite lining supporting structure of weak surrounding rock tunnel - Google Patents

Abstract

The utility model discloses a double-layer molded composite lining support structure for tunnels with weak surrounding rocks, which can reduce construction difficulty, ensure project quality, ensure structural stress stability and construction safety, and reduce project cost at the same time. After the excavation of the surrounding rock of the tunnel, anchor rods, steel mesh, and initial molded concrete layers are respectively provided; outside the initial molded concrete layer, there is a secondary molded concrete layer; between the initial molded concrete layer and the secondary molded concrete layer Has a waterproof layer.

Description

A double-layer molded composite lining support structure for tunnels with weak surrounding rocks

1. Technical field

The utility model relates to a tunnel support structure, in particular to a double-layer molding composite lining support structure for tunnels with weak surrounding rocks. the

2. Background technology

With the construction of large-scale, modernized and high-standard urban roads and transportation projects in my country, the number and construction scale of tunnel projects continue to expand, and weak surrounding rock strata will inevitably be encountered. Weak surrounding rock is descriptively defined as a rock mass with loose structure, poor cementation, broken, swelling, weathering, low strength, large pores, significantly affected by structural plane cutting and weathering, or containing a large amount of expansive clay minerals; its index It is defined as a rock formation with a uniaxial compressive strength of 0.5-25 MPa and _σc /(γH)<2, where _σc is the uniaxial saturated compressive strength, γ is the rock weight, and H is the buried depth of the rock mass. The weak surrounding rock is characterized by poor self-stabilization ability and low strength. Tunnels excavated in this type of rock formation are called weak surrounding rock tunnels.

When the tunnel passes through the weak surrounding rock formation, due to the poor stability of the surrounding rock and the artificial error in the judgment of the stability of the surrounding rock of the tunnel, or improper excavation and support, the tunnel may experience excessive deformation or even instability and landslides. In the construction stage, the self-stabilization time after tunnel excavation is short, and some even have no self-stabilization ability, which is prone to instability and collapse, resulting in engineering accidents; The load acting on the support structure reduces the safety of the support structure; due to the deformation of the tunnel, the initial support shotcrete cracks, the steel frame is twisted and deformed, invades the tunnel boundary, and even collapses, resulting in the failure of follow-up work and affecting the project progress, a waste of manpower, material and financial resources. In my country, projects such as the 4Km-long Guanjiao Tunnel on the Qinghai-Tibet Line, the 3.136Km-long Dazhailing Tunnel on the Baozhong Line, the 1.904Km-long Baoziliang Tunnel, and the Jiazhuqing Railway Tunnel on the Nankun Line that cross the coal-measure strata have all appeared. Excessive deformation of tunnels in different forms and degrees has caused great difficulties in engineering construction. the

Under such background conditions, it is particularly important to prevent and treat excessive deformation and even collapse of weak surrounding rock tunnels. For this reason, tunnel builders have summed up some engineering measures to prevent and treat excessive deformation of weak surrounding rock tunnels in long-term theoretical research and engineering practice, and have achieved some remarkable achievements, such as grouting to strengthen weak surrounding rock mass, Strengthen the tunnel foundation, improve the physical and mechanical properties of the surrounding rock mass; increase the stiffness of the initial support; timely seal the (temporary) inverted arch; expand the bearing area of the arch and wall feet; add long anchors and locking foot anchors (pipes), etc. Among these treatment measures, some theoretical studies are relatively mature and have been applied in engineering practice for a long time, effectively solving the deformation problem of soft rock tunnels, such as grouting to strengthen the weak surrounding rock mass and improving the physical and mechanical properties of the surrounding rock mass ; (Temporary) Inverts are closed in time to make the supporting structure closed into a ring early; additional anchor rods, etc. are added. the

The most widely used composite lining support structure is a double-layer lining composed of spray anchor flexible support on the outer layer and molded concrete secondary lining on the inner layer. It is a supporting structure based on the principle of the New Austrian Method, using anchor rods, shotcrete and steel grids as the main supporting means to control the relaxation and deformation of the surrounding rock. The self-supporting function of the rock adapts to the stress state of the surrounding rock, so that the stress of the lining is adjusted, the cross-sectional stress transitions from a large eccentric to a small eccentric compression, and the surrounding rock and initial support change from a two-dimensional stress state to a three-dimensional stress state. It can better utilize the compressive strength of surrounding rock and concrete, so as to improve the bearing capacity of the lining. the

However, in weak surrounding rock formations, it is very difficult to apply various existing support structure systems and construction methods, and the difficulty of excavation and support far exceeds that of ordinary tunnels. It is beyond reproach that bolt-shotcrete support has been successfully applied in surrounding rocks with better conditions. However, under the complex hydrogeological conditions of weak surrounding rock formations, especially in weak and broken surrounding rocks with rich groundwater, it is difficult for shotcrete to meet the construction requirements. Spray bonding forms support around the tunnel, and the amount of rebound is large; in areas with strict surface settlement requirements, the initial support is required to have greater rigidity and thickness, and it is very labor-intensive and time-consuming to achieve sufficient thickness of shotcrete. Due to the large amount of rebound and the waste of materials, the thickness requirements cannot be met in a short time, which brings difficulties to the construction. the

3. Contents of the invention

In order to solve the deficiencies in the above-mentioned background technology, the utility model provides a double-layer molded composite lining support structure for tunnels with weak surrounding rocks, which can reduce construction difficulty, ensure engineering quality, ensure structural stress stability and construction safety, At the same time reduce the project cost. the

In order to achieve the above object, the technical solution adopted by the utility model is:

A double-layer molded composite lining support structure for tunnels with weak surrounding rocks, characterized in that: after excavation of the surrounding rock of the tunnel, anchor rods, steel mesh, and initial molded concrete layers are respectively provided; outside the initial molded concrete layer, there are The secondary molded concrete layer; a waterproof layer is provided between the initial molded concrete layer and the secondary molded concrete layer. the

Compared with the prior art, the utility model has the following advantages and effects:

1. The double-layer molded lining structure is also reasonable in terms of stress, and it can also limit the deformation of the surrounding rock, so as to achieve the purpose of fully exerting the self-supporting capacity of the surrounding rock itself. the

2. Using formwork to pour initial support concrete, technical measures such as reasonable mix ratio, compact vibration and timely maintenance can be adopted to improve the quality of concrete. the

3. The surface between the double-layer molded linings is very smooth and has no unevenness, so the effect of laying waterproof boards is better, and at the same time reduces material loss and lowers the cost. the

4. Compared with the anchor-sprayed support for the initial support, the steel arch frame can be omitted for the initial formwork support, which reduces the cost. the

5. The use of initial mold support does not produce the rebound of shotcrete material, avoiding material waste and reducing the cost. the

4. Description of drawings

Fig. 1 is the structural representation of the utility model;

Fig. 2 is the A-A sectional view of Fig. 1;

In the figure, 1-initial molded concrete layer, 2-secondary molded concrete layer, 3-waterproof layer, 4-anchor, 5-reinforced mesh

5. Specific implementation

The utility model changes the composite lining support form (anchor rod, steel mesh, shotcrete + secondary molding concrete composite lining) into a double-layer molding composite lining support form ( Anchor rods, steel mesh, primary molded concrete + secondary molded concrete composite lining), the primary support system is changed from flexible support to rigid support, that is, shotcrete is canceled and replaced by primary molded concrete. the

Referring to Fig. 1 and Fig. 2, a double-layer molded composite lining support structure for tunnels with weak surrounding rocks is characterized in that: after excavation of the surrounding rocks of the tunnel, anchor rods 4, steel mesh 5, initial molded concrete Layer 1; a secondary molded concrete layer 2 is provided outside the initial molded concrete layer 1; a waterproof layer 3 is provided between the initial molded concrete layer 1 and the secondary molded concrete layer 2. the

The construction process in the actual project: after the excavation of the surrounding rock of the tunnel, the steel mesh 5 and the anchor rod 4 are firstly constructed, and then the temporary steel arch frame is erected, and the formwork is supported and installed on the temporary steel arch frame. Pour the initial molded concrete 1; after the initial molded concrete layer 1 reaches the age when the mold can be removed, remove the temporary steel arch and formwork, and set a waterproof layer 3 outside the initial molded concrete layer 1; Formwork or formwork trolleys are erected outside the waterproof layer 3 of layer 1, and the secondary molded concrete layer 2 is poured. the

Claims (1)

1. a Support System in Soft Rock Tunnels double-mold is built composite lining supporting and protection structure, it is characterized in that: be respectively equipped with anchor pole (4), steel mesh reinforcement (5), initial stage form concrete layer (1) behind the tunnel surrounding excavation; The outer secondary form concrete layer (2) that is provided with of initial stage form concrete layer (1); Be provided with waterproofing course (3) between initial stage form concrete layer (1) and the secondary form concrete layer (2).

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