阅读说明：本技术 一种全风化花岗岩地层偏压浅埋隧道施工方法 (Construction method of totally weathered granite ground layer bias shallow tunnel ) 是由 谢霖彬 王俊 *** 谢财斌 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地层偏压浅埋隧道施工方法,沿花岗岩地层偏压浅埋隧道施工,包括以下步骤：步骤1)平整场地和设置排水沟；步骤2)沉降观测及监控量测标；步骤3)加固操作；步骤4)设置地表降水井；步骤5)地表深孔注浆；步骤6)正洞施工,通过在隧道洞身穿越全风化花岗岩地层偏压浅埋段前,提前进行围岩整体加固处理,降低正洞围岩的含水率,使正洞轮廓径向一定范围的围岩强度加大,整体粘结性提升,便于正洞开挖时,一次性按设计图纸正常开挖支护,可在隧道掌子面距离全风化花岗岩地层偏压浅埋段较远距离时与正常开挖支护平行施工,根据施工进度提前加固,大大提高了作业效率,节约工期。(The invention relates to the field of tunnel and underground engineering construction, in particular to a construction method of a totally weathered granite ground-bias shallow-buried tunnel, which comprises the following steps of: step 1), leveling a field and arranging a drainage ditch; step 2) settlement observation and monitoring measurement and measurement standards; step 3), reinforcing operation; step 4), arranging a surface dewatering well; step 5), grouting deep holes in the ground surface; and 6) performing main tunnel construction, wherein before the tunnel body passes through the totally weathered granite stratum bias shallow buried section, the whole surrounding rock is reinforced in advance, so that the water content of the surrounding rock of the main tunnel is reduced, the surrounding rock strength of the main tunnel in a radial certain range is increased, the whole cohesiveness is improved, when the main tunnel is excavated, the main tunnel is normally excavated and supported at one time according to a design drawing, the tunnel face can be constructed in parallel with the normal excavation and support when the tunnel face is far away from the totally weathered granite stratum bias shallow buried section, and the main tunnel is reinforced in advance according to the construction progress, so that the operation efficiency is greatly improved, and the construction period is saved.)

1. A construction method of a totally weathered granite ground layer bias shallow tunnel is characterized by comprising the following steps: the construction of the shallow buried tunnel along the granite ground layer by bias voltage comprises the following steps:

step 1), leveling a field and arranging a drainage ditch: leveling the field by adopting manual and mechanical cooperation, arranging drainage ditches at the periphery of the field, and communicating the drainage ditches with natural ditches outside the field;

step 2), settlement observation and monitoring measurement and calibration: excavating the tunnel, setting settlement observation points in the tunnel and on the earth surface, and monitoring, measuring and recording;

step 3), reinforcement operation: reinforcing the tunnel surface, the arch crown and the inverted arch bottom;

step 4), setting an earth surface dewatering well: arranging a plurality of dewatering wells on the surface of the tunnel without reinforcement treatment;

step 5) surface deep hole grouting: forming grouting holes on the reinforced tunnel ground surface and performing deep hole grouting;

step 6), main hole construction: and (5) excavating and supporting the tunnel main tunnel.

2. The construction method of the totally weathered granite ground layer shallow buried tunnel according to claim 1, characterized in that: and 2) plugging the tunnel face of the excavated tunnel, and carrying out net hanging and slurry spraying on the tunnel face, wherein the thickness i of the net hanging and slurry spraying on the tunnel face is more than or equal to 20 cm.

3. The construction method of the totally weathered granite ground-based shallow tunnel according to claim 1, wherein the reinforcing range of the tunnel ground surface in the step 3) is that the left and right contour lines of the tunnel opening extend outwards by 4m ~ 6m, the reinforcing range of the tunnel arch is that the arch top extends upwards by 7m ~ 9m, and the reinforcing range of the tunnel inverted arch bottom extends downwards by 1m ~ 3 m.

4. The construction method of the totally weathered granite ground layer shallow buried tunnel according to claim 1, characterized in that: and in the step 4), the dewatering well is positioned below the inverted arch bottom, and the distance p from the bottom of the dewatering well to the inverted arch bottom is more than or equal to 3 m.

5. The construction method of the totally weathered granite ground-layer shallow tunnel according to claim 1, wherein the grouting holes in the step 5) are arranged in an equilateral triangle on the ground surface of the tunnel, the distance between any two adjacent grouting holes is 1.4 m ~ 1.6.6 m, and the diameter of each grouting hole is 125 mm-150 mm.

6. The construction method of the totally weathered granite ground layer shallow buried tunnel according to claim 1, characterized in that: and 4) a filter pipe is arranged in the dewatering well in the step 4), the side wall of the filter pipe is provided with a plurality of filter holes, and the filter holes are arranged on the side wall of the filter pipe in a quincunx shape.

7. The construction method of the totally weathered granite ground layer shallow buried tunnel according to claim 1, characterized in that: and 5) arranging a grouting pipe in the grouting hole, injecting a casing material between the inner wall of the grouting hole and the outer wall of the grouting pipe, and then injecting grouting material into the grouting pipe.

8. The construction method of the totally weathered granite ground layer shallow buried tunnel according to claim 7, characterized in that: the shell material is a mixture of bentonite and cement paste, wherein the weight ratio of water: cement paste: the mass ratio of the bentonite is 1.6:1: 1.

9. The construction method of the totally weathered granite ground layer shallow buried tunnel according to claim 7, characterized in that: the grouting material is a mixture of sulphoaluminate cement, Portland cement and water glass.

10. The construction method of the totally weathered granite ground layer shallow buried tunnel according to claim 7, characterized in that: the grouting operation adopts a retreating type sectional grouting process.

Technical Field

The invention relates to the field of tunnel and underground engineering construction, in particular to a construction method of a totally weathered granite ground layer bias shallow tunnel.

Background

With the development of science and technology, the civil engineering industry in China is vigorous, and various tunnel projects are not lacked. The tunnel body often passes through the completely weathered granite stratum, and especially when the stratum is in a V-shaped gully section, the moisture content of surrounding rock is often larger, and the completely weathered granite is sandy soil-shaped, is disintegrated and lost when meeting water, and is easy to collapse, so that the construction difficulty is caused. And the clearance is minimum compared with ordinary mud rock granule for the fully weathered granite granule, and traditional tunnel inner conduit slip casting local reinforcement effect is relatively poor, and the thick liquid pulse is difficult to spread, and is consuming time and power, and "V" type gully district often accompanies bias voltage, shallow burying in addition, and the tunnel is first to be out of shape seriously during the construction, and the earth's surface subsides fracture, brings serious potential safety quality hazard for the construction, and the construction is slow, and the time limit for a project influences greatly.

In summary, a construction method of a totally weathered granite ground layer bias shallow tunnel is needed.

Disclosure of Invention

In view of the above problems, the invention aims to provide a construction method of a totally weathered granite ground layer bias shallow tunnel.

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

a construction method of a totally weathered granite ground layer bias shallow tunnel comprises the following steps of:

step 1), leveling a field and arranging a drainage ditch: leveling the field by adopting manual and mechanical cooperation, arranging drainage ditches at the periphery of the field, and communicating the drainage ditches with natural ditches outside the field;

step 2), settlement observation and monitoring measurement and calibration: setting settlement observation points in the tunnel and the ground surface, and monitoring, measuring and recording;

step 3), reinforcement operation: reinforcing the tunnel surface, the arch crown and the inverted arch bottom;

step 4), setting an earth surface dewatering well: arranging a plurality of dewatering wells on the surface of the tunnel without reinforcement treatment;

step 5) surface deep hole grouting: forming grouting holes on the reinforced tunnel ground surface and performing deep hole grouting

Step 6), main hole construction: and (5) excavating and supporting the tunnel main tunnel.

Firstly, excavating and filling local areas with uneven topography, leveling the ground by matching an excavator and a loader with manpower, arranging drainage ditches at the periphery of the leveled ground, guiding surface water into external natural ditches through the drainage ditches to ensure smooth drainage of the ground, preventing granite in a tunnel construction section from being affected by soaking of accumulated water, arranging settlement observation points in a tunnel hole so as to monitor and measure deformation quantity at any time, stabilizing the tunnel by reinforcing the ground surface, an arch crown and an inverted arch bottom, selecting proper positions outside a reinforcing range to arrange a certain number of ground surface dewatering wells, arranging a water pump in the tunnel to periodically pump and drain water so as to reduce the water content of surrounding rocks in a main hole range, arranging grouting holes on the reinforced tunnel ground surface and carrying out deep hole grouting to reinforce the main hole and the radial surrounding rocks of the main hole, thereby being beneficial to the subsequent main hole excavation of the tunnel, through the whole reinforcement processing to the country rock, reduce the moisture content of just hole country rock, make the radial country rock intensity of just hole profile strengthen, whole cohesiveness promotes, when being convenient for just hole excavation, normal excavation is strutted to improve the operating efficiency greatly, practice thrift the time limit for a project, not only played the guarantee effect of quality safety in the bias pressure shallow tunnel construction process that buries in the completely weathering granite stratum, also reduced the secondary disaster's of structure safety that probably appears risk by a wide margin.

Preferably, in the step 2), the excavated tunnel face of the tunnel is plugged, screened and gunited, the thickness i of the tunnel face screened and gunited is greater than or equal to 20cm, the tunnel face is a working face of the tunnel which is continuously pushed forward, and when the distance between the tunnel face and the reinforced area is less than 5m, the excavated tunnel face is plugged, screened and gunited, so that the thickness i of the tunnel face screened and gunited is greater than or equal to 20cm, and the tunnel is favorably stabilized.

Preferably, in the step 3), the reinforcing range of the tunnel ground surface is that the left and right contour lines of the tunnel opening extend outwards by 4m ~ 6m, the reinforcing range of the tunnel arch is that the arch top extends upwards by 7m ~ 9m, and the reinforcing range of the tunnel inverted arch bottom extends downwards by 1m ~ 3 m.

Preferably, the dewatering well in the step 4) is positioned below the inverted arch bottom, and the distance from the bottom of the dewatering well to the inverted arch bottom is more than or equal to 3 m.

Preferably, the grouting holes in the step 5) are arranged on the ground surface of the tunnel in an equilateral triangle, the distance between any adjacent grouting holes is 1.4 m ~ 1.6.6 m, and the aperture diameter of each grouting hole is 125 mm-150 mm.

Preferably, a filter pipe is arranged in the dewatering well in the step 4), the side wall of the filter pipe is provided with a plurality of filter holes, and the filter holes are arranged on the side wall of the filter pipe in a quincunx shape.

Preferably, in the step 5), a grouting pipe is arranged in the grouting hole, and after the casing material is injected between the inner wall of the grouting hole and the outer wall of the grouting pipe, the grouting material is injected into the grouting pipe.

Preferably, the casing material is a mixture of bentonite and cement paste, wherein the weight ratio of water: cement paste: the mass ratio of the bentonite is 1.6:1: 1.

Preferably, the slip casting agent is a mixture of sulphoaluminate cement, Portland cement and water glass.

Preferably, the grouting operation adopts a retreating type sectional grouting process, namely grouting is carried out in a grouting section from the bottom of a hole, the sectional step distance is 1m, after a first grouting section is injected, a grouting core pipe is retreated, grouting in a second grouting section is carried out, circulation is carried out until the grouting section is grouted, the grouting sequence is that two rows of holes on the outermost side are firstly grouted, then the holes are sequentially pushed inwards, holes at two ends are firstly grouted in each row of grouting holes, and then alternate grouting is carried out. The initial pressure of grouting is 0.4-0.6 Mpa, and the final pressure is 4-6 Mpa.

Compared with the prior art, the invention has the advantages that: the invention relates to a construction method of a totally weathered granite stratum bias shallow-buried tunnel, which comprises the steps of digging and filling a local area with uneven topography, leveling the ground by matching an excavator and a loader with manpower, arranging drainage ditches at the periphery of the leveled ground, guiding surface water into external natural ditches through the drainage ditches to ensure smooth drainage of the ground, preventing granite in a tunnel construction section from being affected by soaking of accumulated water, arranging settlement observation points in a tunnel hole to monitor and measure deformation at any time, stabilizing the tunnel by reinforcing the ground surface, an arch crown and an inverted arch bottom, selecting proper positions outside a reinforcing range, arranging a certain number of surface water-lowering wells, arranging a water pump in the wells to pump and drain water periodically so as to reduce the water content of surrounding rocks in the range of the main hole, arranging grouting holes on the reinforced tunnel ground surface and carrying out deep hole grouting to reinforce the main hole and the radial surrounding rocks of the main hole, the method is beneficial to subsequent tunnel main tunnel excavation supporting, the moisture content of the main tunnel surrounding rock is reduced through integral reinforcement treatment of the surrounding rock, the strength of the main tunnel contour radial surrounding rock is increased, the integral cohesiveness is improved, and normal excavation supporting is facilitated when the main tunnel is excavated, so that the operation efficiency is greatly improved, the construction period is saved, the quality safety guarantee effect is played in the tunnel construction process, and the risk of possible structural safety secondary disasters is greatly reduced.

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

1. when the distance between the tunnel face and the reinforcing area is less than 5m, the excavated tunnel face is plugged, screened and sprayed, so that the thickness i of the screened and sprayed tunnel face is greater than or equal to 20cm, and the tunnel is stabilized.

2. And (3) a retreating type sectional grouting process, namely grouting from the hole bottoms in the grouting sections, wherein the sectional step distance is 1m, after the first grouting section is grouted, retreating the grouting core pipe, grouting the second grouting section, circulating the steps until the grouting sections are grouted, wherein the grouting sequence is that two rows of holes on the outermost side are firstly grouted, then the holes are sequentially pushed inwards, and holes at two ends are firstly grouted in each row of grouting holes, and then the holes are alternately grouted at intervals. The initial pressure of grouting is 0.4-0.6 Mpa, and the final pressure is 4-6 Mpa.

Drawings

FIG. 1 is a process flow diagram of the construction method of a totally weathered granite ground layer bias shallow tunnel according to the invention.

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.