阅读说明：本技术 一种全风化花岗岩偏压陡坡隧道进洞施工方法 (Completely weathered granite bias steep slope tunnel entry construction method ) 是由 谢财斌 王俊 *** 谢霖彬 于 2019-10-17 设计创作，主要内容包括：本发明涉及隧道及地下工程施工领域,尤其涉及一种全风化花岗岩偏压陡坡隧道进洞施工方法,沿花岗岩偏压陡坡段的隧道洞口施工,包括以下步骤：步骤1)截水沟和排水沟开挖；步骤2)边坡防护；步骤3)仰坡防护；步骤4)打设旋喷桩；步骤5)打设降水井；步骤6)导向墙施工；步骤7)超前长管棚施工；步骤8)隧道开挖施工,可有效解决全风化花岗岩遇水膨胀,颗粒崩解,边坡和仰坡自稳能力,易垮塌,滑坡,全风化花岗岩含水呈软塑状态,洞身轮廓线不易形成,开挖风险大,易塌方,地基承载力达不到设计要求,地基沉降量较大的问题。(The invention relates to the field of tunnel and underground engineering construction, in particular to a construction method for tunneling a totally weathered granite bias steep slope tunnel, which is constructed along a tunnel portal at a granite bias steep slope section and comprises the following steps: step 1), excavating an intercepting ditch and a drainage ditch; step 2), slope protection; step 3), slope ascending protection; step 4), driving and arranging a rotary jet grouting pile; step 5), digging a dewatering well; step 6), constructing a guide wall; step 7) construction of an advanced long pipe shed; and step 8) tunnel excavation construction can effectively solve the problems that the completely weathered granite expands when meeting water, particles disintegrate, the self-stability of a side slope and an upward slope is high, the completely weathered granite is easy to collapse and slide, the water content of the completely weathered granite is in a soft plastic state, the outline of a hole body is not easy to form, the excavation risk is high, the completely weathered granite is easy to collapse, the bearing capacity of a foundation cannot meet the design requirement, and the settlement amount of the foundation is large.)

1. A fully weathered granite steep slope tunnel entry construction method is characterized by comprising the following steps: the tunnel portal construction along the granite bias steep section comprises the following steps:

step 1), excavating intercepting ditches and drainage ditches: digging an intercepting ditch and a drainage ditch in the bias pressure section, so that the intercepting ditch and the drainage ditch are communicated with the existing ditch at the opening of the tunnel;

step 2) slope protection: arranging a plurality of anchoring piles on a slope of the tunnel portal;

step 3), slope ascending protection: carrying out load reduction on earth and rock on an upward slope of the tunnel portal and then performing anchor spraying and supporting;

step 4), driving a rotary jet grouting pile: driving rotary spraying piles along the outer sides of the gutter at the tunnel portal;

step 5), digging a dewatering well: a dewatering well is drilled at the bottom of the gutter at the tunnel portal;

step 6), construction of a guide wall: setting out and excavating a guide wall section, erecting a steel frame along the guide wall section, pre-burying a guide steel pipe on the steel frame, and finally pouring the guide wall;

step 7) construction of an advanced long pipe shed: drilling a tunnel, mounting a pipe shed in the hole, and grouting;

step 8) tunnel excavation construction: and (5) adopting a four-step CD method to carry out tunnel excavation construction.

2. The completely weathered granite steep slope tunnel cave construction method according to claim 1, characterized in that: and in the step 2), the anchoring pile is constructed and installed on the side slope by adopting a pile jumping method.

3. The completely weathered granite steep slope tunnel cave construction method according to claim 1, characterized in that: and 3) adopting step type clearing and load reduction for the earth and the stone on the upward slope in the step 3), and performing spray anchor support layer by layer.

4. The completely weathered granite steep slope tunnel cave construction method according to claim 1, characterized in that: and 4) driving double rows of rotary spraying piles at the outer side of the gutter at the tunnel entrance in the step 4).

5. The construction method for the totally weathered granite bias steep slope tunnel to enter the tunnel according to claim 2, wherein the diameter of the jet grouting piles is 0.4m ~ 0.6.6 m, the distance between every two adjacent jet grouting piles is 0.3m ~ 0.5.5 m, and the distance between the top end of each jet grouting pile and the bottom of the inverted arch of the tunnel is 0.9m ~ 1.1.1 m.

6. The method for constructing the totally weathered granite bias steep slope tunnel according to claim 1, wherein the pore size of the precipitation well in the step 5) is 0.1m ~ 0.3.3 m, the distance between adjacent precipitation wells is 1.9m ~ 2.1.1 m, the precipitation well is positioned below the inverted arch bottom, and the distance from the bottom of the precipitation well to the inverted arch bottom of the tunnel is 0.9 ~ 1.1.1 m.

7. The construction method for the totally weathered granite bias steep slope tunnel to enter the tunnel according to claim 4, characterized in that a precipitation well of 7 ~ 9 openings is dug in the gutter at the tunnel opening.

8. The completely weathered granite bias-pressure steep-slope tunnel cave construction method as claimed in claim 1, wherein the guide wall of the step 6) is cast by C20 concrete, and the cross-sectional dimension of the guide wall is 0.8m x 0.8m ~ 1.0.0 m x 1.0 m.

9. The completely weathered granite steep slope tunnel boring construction method according to claim 8, wherein the framework of the guide wall in the step 6) is formed by connecting two I-beams, the distance between the I-beams is 0.5m ~ 0.7.7 m, the length of the guide steel pipe is 0.9m ~ 1.1.1 m, and the distance between the adjacent guide steel pipes is 0.3m ~ 0.5.5 m.

10. The completely weathered granite steep slope tunnel cave construction method according to claim 1, characterized in that: and 7) adopting cement slurry as the grouting material, wherein the weight ratio of water to ash in the cement slurry is 1:1, and the grouting pressure is 0.5-1.5 Mpa.

Technical Field

The invention relates to the field of tunnel and underground engineering construction, in particular to a completely weathered granite bias steep slope tunnel entry construction method.

Background

In current high-speed railway tunnel construction, the fully weathered granite meets water swelling, the granule disintegrates, there is not the ability of stabilizing oneself, as the stratum condition on the upward slope, easily collapse, the landslide, the fully weathered granite moisture is soft state of moulding, the hole body contour line is difficult for forming, the excavation risk is big, and the fully weathered granite is the flow state of moulding after being soaked by the water, lead to the ground settlement volume great, consequently, it is big to the tunnel construction degree of difficulty of entering the hole of the full weathered granite bias steep slope section tunnel, the time limit for a project is long, the hole body settlement volume is great, thereby collapse and rework accident appear easily, probably cause the cost to drop into and increase, and the potential safety hazard is big, construction quality is.

In summary, a construction method for fully weathered granite bias steep slope tunnel entrance is needed at present.

Disclosure of Invention

In view of the above problems, the invention aims to provide a completely weathered granite bias steep slope tunnel entry construction method.

In order to achieve the purpose, the invention adopts the technical scheme that:

a construction method for entering a tunnel of a totally weathered granite bias steep slope tunnel is implemented along a tunnel portal of a granite bias steep slope section, and comprises the following steps:

step 1), excavating intercepting ditches and drainage ditches: digging an intercepting ditch and a drainage ditch in the bias pressure section, so that the intercepting ditch and the drainage ditch are communicated with the existing ditch at the opening of the tunnel;

step 2) slope protection: arranging a plurality of anchoring piles on a slope of the tunnel portal;

step 3), slope ascending protection: carrying out load reduction on earth and rock on an upward slope of the tunnel portal and then performing anchor spraying and supporting;

step 4), driving a rotary jet grouting pile: driving rotary spraying piles along the outer sides of the gutter at the tunnel portal;

step 5), digging a dewatering well: a dewatering well is drilled at the bottom of the gutter at the tunnel portal;

step 6), construction of a guide wall: setting out and excavating a guide wall section, erecting a steel frame along the guide wall section, pre-burying a guide steel pipe on the steel frame, and finally pouring the guide wall;

step 7) construction of an advanced long pipe shed: drilling a tunnel, mounting a pipe shed in the hole, and grouting;

step 8) tunnel excavation construction: and (5) adopting a four-step CD method to carry out tunnel excavation construction.

The method is characterized in that a common water system in a bias tunnel is developed, the surface runoff is large, after excavation of earth and stone in a gully is finished, a cut-off ditch and a drainage ditch are excavated, outlets of the cut-off ditch and the drainage ditch are communicated with a ditch of a tunnel portal, smooth drainage in the tunnel is ensured, granite in a tunnel construction section is not affected by soaking of accumulated water, anchoring piles are arranged on side slopes of the tunnel portal to have the function of stabilizing side slopes, for a steep slope bias section, the existing mountain shape needs to be reasonably designed before construction, proper slope rate is selected, clearing and load reduction are preferably carried out on the steep slope, top load is reduced, initial deformation is effectively controlled, an upward slope is stabilized through anchor spraying support, and as the whole granite is in a flow plastic state after being soaked by water, in order to prevent underground water from entering the portal section, jet grouting piles are arranged on the outer side of a gutter at the tunnel portal, foundations are reinforced, smooth construction of a guide wall and contour lines of the portal are ensured, the underground water level can be effectively reduced by digging a precipitation well at the bottom of a tunnel entrance gutter, pumping water in the precipitation well by a water pump, guiding an arch wall along the extending direction of the tunnel through the tunnel entrance, wherein the arch wall has a bearing effect on the tunnel and can effectively prevent the tunnel from collapsing, guiding steel pipes are pre-embedded on a steel frame to guide the direction of pipe shed construction, the advance support of the pipe shed can enhance the bearing capacity of the stratum during the digging process, finally, a four-step CD method is adopted, namely, a method for separately digging by using steel supports and partition walls for spraying concrete is used for digging, the ground settlement during the tunnel digging construction can be reduced, and the problem of water expansion caused by weathering is effectively solved by the matching of water interception ditch and drainage ditch digging, anchoring pile construction, upward slope protection, rotary spraying pile digging, water lowering well digging, guiding wall construction, advance long pipe shed construction and tunnel digging construction, the particles are disintegrated, the slope and the upward slope have self-stability, the fully weathered granite is easy to collapse and slide, the water content of the fully weathered granite is in a soft plastic state, the outline of the hole body is not easy to form, the excavation risk is large, the collapse is easy, the bearing capacity of the foundation can not meet the design requirement, and the settlement amount of the foundation is large.

Preferably, in the step 2), the anchor piles are constructed on the side slope by adopting a pile jumping method, the pile jumping construction is performed on rows of piles or in construction, if adjacent piles are closely spaced, the first, third, fifth and other piles which are firstly poured are adopted to have certain strength, and then the second and fourth piles are continuously poured so as to avoid the condition that the strength of the piles is reduced due to the influence of the construction of the adjacent piles.

Preferably, in the step 3), the earth and the stone on the upward slope are subjected to stepped clearing and load reduction, and are subjected to anchor spraying and supporting layer by layer, and the earth and the stone are subjected to anchor spraying and supporting layer by layer after the stepped clearing and load reduction on the upward slope, so that the top load of the upward slope can be reduced, and the initial deformation of the upward slope can be controlled.

Preferably, in the step 4), double rows of rotary spraying piles are arranged on the outer side of the tunnel entrance gutter in a driving mode, and double rows of rotary spraying piles are arranged on the outer side of the tunnel entrance gutter in a driving mode, so that the foundation strength on the outer side of the gutter can be effectively enhanced.

Preferably, the diameter of the jet grouting pile is 0.4m ~ 0.6m, the distance between adjacent jet grouting piles is 0.3m ~ 0.5m, and the distance from the top end of the jet grouting pile to the bottom of the tunnel inverted arch is 0.9m ~ 1.1.1 m.

Preferably, in the step 5), the aperture size of the dewatering well is 0.1m ~ 0.3.3 m, the distance between adjacent dewatering wells is 1.9m ~ 2.1.1 m, the dewatering well is positioned below the inverted arch bottom, and the distance between the bottom of the dewatering well and the inverted arch bottom of the tunnel is 0.9m ~ 1.1.1 m.

Preferably, a 7 ~ 9 dewatering well is drilled at the bottom of the tunnel portal gutter, a 7 ~ 9 dewatering well is drilled in the tunnel portal gutter, and the water in the dewatering well can be pumped by a water pump to quickly and effectively reduce the underground water level.

Preferably, the guide wall in the step 6) is cast by using C20 concrete, and the cross section of the guide wall is 0.8m multiplied by 0.8m ~ 1.0.0 m multiplied by 1.0 m.

Preferably, the framework of the guide wall in the step 6) is formed by connecting two I-beams, the distance between the I-beams is 0.5m ~ 0.7.7 m, the length of each guide steel pipe is 0.9m ~ 1.1.1 m, and the distance between adjacent guide steel pipes is 0.3m ~ 0.5.5 m.

Preferably, in the step 7), the grouting material is cement slurry, the weight ratio of water to ash in the cement slurry is 1:1, and the grouting pressure is 0.5-1.5 Mpa.

Compared with the prior art, the invention has the advantages that: the invention relates to a construction method for entering a hole of a totally weathered granite bias steep slope tunnel, which is characterized in that a common water system in the bias tunnel is developed, the earth surface runoff is large, after the excavation of earth and stone sides in a gully is finished, a cut-off gully and a drainage gully are excavated, the outlets of the cut-off gully and the drainage gully are communicated with a ditch of a tunnel opening, the drainage in the tunnel is smooth, the granite in the tunnel construction section is not affected by the soaking of accumulated water, an anchoring pile is arranged on the side slope of the tunnel opening to stabilize the side slope, for the steep slope bias section, the existing mountain shape is reasonably designed before the construction, the proper slope rate is selected, the steep slope is suitable for clearing and reducing the load, the top load is reduced to effectively control the initial deformation, the upward slope is stabilized through a spray anchor, the totally weathered granite is in a flow plastic state after being soaked in water, in order to prevent underground water from entering the construction section, a rotary spray pile is arranged on the outer, the foundation is reinforced, the smooth construction of the guide wall and the formation of the outline of the tunnel body are ensured, the water-lowering well is arranged at the bottom of the gutter at the tunnel entrance, the water in the water-lowering well is pumped by a water pump to effectively reduce the underground water level, the arch wall is guided along the extending direction of the tunnel through the tunnel entrance and has the bearing effect on the tunnel, the collapse of the tunnel can be effectively prevented, the guide steel pipe is pre-embedded on a steel frame to guide the construction direction of the pipe shed, the advance support of the pipe shed can enhance the bearing capacity of the stratum in the excavation process, finally, the ground settlement in the construction process can be reduced by adopting a four-step CD method to carry out the tunnel excavation construction, and the full weathering water-encountering expansion can be effectively solved through the cooperation of the excavation of a water interception ditch and a drainage ditch, the construction of an anchoring pile, the upward slope protection, the arrangement of a jet grouting pile, the arrangement of, the particles are disintegrated, the slope and the upward slope have self-stability, the fully weathered granite is easy to collapse and slide, the water content of the fully weathered granite is in a soft plastic state, the outline of the hole body is not easy to form, the excavation risk is large, the collapse is easy, the bearing capacity of the foundation can not meet the design requirement, and the settlement amount of the foundation is large.

The beneficial effects of other embodiments of the application are as follows:

1. and after the load is reduced by the step clearing on the upward slope, the anchor spraying and supporting are carried out layer by layer, so that the top load of the upward slope can be reduced, and the initial deformation of the upward slope can be controlled.

2. Double-row rotary spraying piles are arranged on the outer side of the gutter at the tunnel opening, so that the foundation strength on the outer side of the gutter can be effectively enhanced.

3. Double-row rotary spraying piles are arranged on the outer side of the gutter at the tunnel opening, so that the foundation strength on the outer side of the gutter can be effectively enhanced.

4. A7 ~ 9-mouth dewatering well is arranged in the gutter at the tunnel portal, and the underground water level can be quickly and effectively reduced by pumping water in the dewatering well through a water pump.

Drawings

FIG. 1 is a process flow diagram of a construction method for entering a hole of a totally weathered granite bias steep-slope tunnel according to the invention;

FIG. 2 is a process flow diagram of a CD method construction process of the completely weathered granite bias steep slope tunnel cave entering construction method.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.