阅读说明：本技术 一种上软下硬地层中浅埋隧道基坑围护施工方法 (Shallow tunnel foundation pit enclosure construction method in upper-soft lower-hard stratum ) 是由 牛富生 卓越 杨泽平 王光辉 刘永胜 李治国 陈海军 杨朝帅 蒋永星 罗会如 于 2020-05-29 设计创作，主要内容包括：本发明公开了一种上软下硬地层中浅埋隧道基坑围护施工方法：步骤一、在隧道浅埋段先放坡开挖,根据设计要求确定基坑围护段,并在基坑围护段施作门架式围护结构。步骤二、基坑围护段的下部岩石采取“跳马口”中槽开挖方式。步骤三、在岩石预留区的左右侧,分别在距离同侧围护桩1m～2m处纵向切割,形成一切割线；在切割线的靠近同侧围护桩侧为弱劈裂区,远离同侧围护桩侧为强劈裂区。步骤四、先对一侧强劈裂区分段施工,然后对同侧所述弱劈裂区分段施工,单次施工段与松动爆破法分段开挖的距离相等；重复在另一侧开挖施工,完成单幅隧道跨度范围内的一段岩石开挖。采用该施工方法,对围护桩的影响小,避免围护桩断裂造成的基坑失稳坍塌。(The invention discloses a construction method for enclosure of a shallow tunnel foundation pit in a stratum with a soft upper part and a hard lower part, which comprises the following steps: firstly, slope excavation is carried out on a shallow buried section of a tunnel, a foundation pit enclosure section is determined according to design requirements, and a portal enclosure structure is constructed on the foundation pit enclosure section. And step two, excavating the lower rock of the foundation pit enclosure section in a 'horse jump opening' middle groove mode. Step three, longitudinally cutting the left side and the right side of the rock reserved area at a position 1-2 m away from the fender post at the same side to form a cutting line; the side of the cutting line close to the fender pile on the same side is a weak splitting area, and the side of the cutting line far away from the fender pile on the same side is a strong splitting area. Constructing strong splitting zones on one side in a segmented mode, constructing weak splitting zones on the same side in a segmented mode, and enabling the distance between a single construction segment and the segmented excavation by a loosening blasting method to be equal; and (5) repeatedly carrying out excavation construction on the other side to finish the excavation of a section of rock in the span range of the single tunnel. By adopting the construction method, the influence on the fender post is small, and the unstable collapse of the foundation pit caused by the fracture of the fender post is avoided.)

1. A construction method for enclosure of a shallow tunnel foundation pit in a stratum with a soft upper part and a hard lower part is characterized by comprising the following steps:

firstly, putting a slope on a shallow buried section of a tunnel and excavating to the bottom of a foundation pit of the designed shallow buried tunnel; constructing a portal type enclosure structure (6) in the foundation pit enclosure section (1);

step two, divide into not hard up blasting district (2) and rock reservation district (3) with the tunnel excavation wall of foundation ditch enclosure section (1), wherein: the loosening blasting area (2) is rock distributed left and right in the 1/3B span range along the central line (a) of the single tunnel, and the area between the outer side of the loosening blasting area (2) and the enclosure piles of the enclosure structure is a rock reserved area (3); wherein: b is the excavation width of the single tunnel;

step three, longitudinally excavating a section of rock in the loosening blasting area (2);

fourthly, longitudinally cutting the inner sides of the fender posts which are positioned in the left and right rock reserved areas (3) and are positioned at the same side respectively to form a cutting line (4); the distance of one longitudinal cutting is equal to the distance of one excavation of the loosening blasting area section; the side of the cutting line (4) close to the fender pile on the same side is a weak splitting area (3-2), and the side of the cutting line far away from the fender pile on the same side is a strong splitting area (3-1);

fifthly, firstly carrying out first-stage excavation construction on the strong splitting area (3-1) on one side, and then carrying out first-stage excavation construction on the weak splitting area (3-2) on the same side; the excavation construction on the other side is repeated, and the excavation of a section of rock in the span range of the single tunnel is completed;

constructing an inverted arch in the tunnel of the excavated section, connecting the inverted arch with a fender post of a building enclosure, forming a space with the building enclosure, backfilling the tunnel pavement in the space to the elevation, and reserving a blasting operation space in the space;

and seventhly, repeating the third step and the sixth step to finish the excavation of the whole tunnel.

2. The method for constructing the shallow tunnel foundation pit support in the upper soft and lower hard stratum as claimed in claim 1, wherein the cutting depth of the cutting line exceeds the outer side line of the inverted arch.

3. The method for constructing the shallow tunnel foundation pit enclosure in the upper soft and lower hard stratum according to the claim 1 or 2, characterized in that the distance between each cutting line (4) and the enclosure piles on the same side is 1 m-2 m.

4. The method for constructing the shallow tunnel foundation pit enclosure in the stratum with the soft upper part and the hard lower part as claimed in claim 3, wherein a handheld hydraulic splitter is adopted for construction in the weak splitting area.

5. The method for constructing the shallow tunnel foundation pit enclosure in the stratum with the soft upper part and the hard lower part as claimed in claim 4, wherein an onboard large-scale rock splitter is adopted for construction in the strong splitting area (3-1).

6. The construction method for the shallow tunnel foundation pit enclosure in the upper soft and lower hard stratum according to claim 5, wherein in the loose blasting area (2), the boundaries of the arrangement of the middle trench excavation blastholes (5) are as follows: the upper surface is positioned on the surface of the bedrock, and the lower surface is positioned at the outer side line of the inverted arch.

7. The method for constructing the shallow tunnel foundation pit enclosure in the stratum with the soft upper part and the hard lower part as claimed in claim 6, wherein each section is 6m in the sectional construction.

[ technical field ] A method for producing a semiconductor device

The invention belongs to construction of a shallow tunnel foundation pit enclosure section, and particularly relates to a shallow tunnel foundation pit enclosure construction method in a stratum with a soft upper part and a hard lower part.

[ background of the invention ]

The rock tunnel is generally constructed by blasting excavation, and after blasting, the rock tunnel is transported to a specified slag abandoning field by an automobile. During blasting, blast holes are distributed to be formed according to the design contour line of the side wall of the tunnel, surrounding rock damage is prevented, and therefore the blasting effect is good. And blasting holes are arranged according to the principle of design contour lines during rock blasting of the lower part of the enclosure section of the shallow tunnel foundation pit, and presplitting blasting full-width one-step forming excavation is adopted for the lower part stone excavation, so that the construction speed is high. However, the enclosure section of the foundation pit of the shallow-buried tunnel is provided with a fender post structure, the surrounding blastholes are close to the fender post structure, so that blasting operation is greatly harmful to the fender post, and the fender post can be broken to cause unstable collapse of the foundation pit.

[ summary of the invention ]

The invention aims to provide a construction method for enclosure of a shallow tunnel foundation pit in a stratum with a soft upper part and a hard lower part, which reduces the influence of tunnel excavation vibration on enclosure piles, and avoids unstable collapse of the foundation pit caused by fracture of the enclosure piles.

The invention adopts the following technical scheme: a construction method for enclosure of a shallow tunnel foundation pit in a stratum with a soft upper part and a hard lower part comprises the following steps:

firstly, putting a slope on a shallow buried section of a tunnel and excavating to the bottom of a foundation pit of the designed shallow buried tunnel; constructing a portal type enclosure structure in the foundation pit enclosure section;

step two, adopting a 'horse jump mouth' middle groove excavation mode for the lower part rock of the foundation pit enclosure section, specifically comprising the following steps: dividing the tunnel excavation wall surface of the foundation pit enclosure section into a loosening blasting area and a rock reserved area, wherein: the loosening blasting area is rock distributed left and right in the 1/3B span range along the center line of the single tunnel, and the area between the outer side of the loosening blasting area and the enclosure piles of the enclosure structure is a rock reserved area; wherein: b is the excavation width of the single tunnel;

step three, longitudinally excavating a section of rock in the loosening blasting area;

step four, longitudinally cutting the inner sides of the fender posts which are respectively positioned at the same side in the rock reserved areas at the left side and the right side to form a cutting line; the distance of one longitudinal cutting is equal to the distance of one excavation of the loosening blasting area section; the side of the cutting line close to the fender pile on the same side is a weak splitting area, and the side of the cutting line far away from the fender pile on the same side is a strong splitting area;

fifthly, firstly carrying out one-section excavation construction on the strong splitting area at one side, and then carrying out one-section excavation construction on the weak splitting area at the same side; the excavation construction on the other side is repeated, and the excavation of a section of rock in the span range of the single tunnel is completed;

constructing an inverted arch in the tunnel of the excavated section, connecting the inverted arch with a guard post of the enclosure structure, forming a space with the enclosure structure, backfilling the tunnel pavement in the space to the elevation, and reserving a blasting operation space in the space;

and seventhly, repeating the third step and the sixth step to finish the excavation of the whole tunnel.

Further, the cutting line has a cutting depth exceeding the outer side line of the inverted arch.

Further, the distance between each cutting line and the fender pile on the same side is 1 m.

And further, in the weak splitting area, a handheld hydraulic splitter is adopted for construction.

Furthermore, in a strong splitting area, an airborne large-scale rock splitter is adopted for construction.

Further, in the loose blasting area, the arrangement boundaries of the blast holes of the middle groove excavation are as follows: the upper surface is positioned on the surface of the bedrock, and the lower surface is positioned at the outer side line of the inverted arch.

Further, each segment is 6m in the segmented construction.

The invention has the beneficial effects that: dividing the tunnel excavation wall surface into a loosening blasting area and a rock reserved area, excavating the loosening blasting area firstly, then excavating and constructing in the rock reserved area, and dividing the rock reserved area on one side of the center line of the tunnel into a weak splitting area and a strong splitting area which are relatively independent, wherein the strong splitting area is relatively independent, so that the influence of splitting vibration waves on the fender post during construction of the strong splitting area is small; weak splitting district is close to the fender pile, adopts the less hand-held type hydraulic pressure splitting machine operation of vibrations noise, and is less to the vibration influence of fender pile like this, has avoided because the fender pile fracture leads to the risk that the foundation ditch unstability collapses.

[ description of the drawings ]

FIG. 1 is a schematic longitudinal section view of a shallow tunnel foundation pit enclosure;

FIG. 2 is a schematic diagram of fine construction operation of a rock section at the lower part of the single shallow tunnel foundation pit enclosure;

FIG. 3 is a schematic view of a double-width shallow tunnel foundation pit enclosure section structure;

fig. 4 is a schematic plan view of a single shallow tunnel foundation pit enclosure.

Wherein: a. a tunnel centerline; 1. a foundation pit support section; 2. loosening the blasting area; 3. a rock reserve; 3-1, strong cleavage area; 3-2. weak cleavage region; 4. cutting a line; 5. excavating blast holes in the middle groove; 6. an enclosure structure; 6-1. fender posts; 6-2, a cross brace; 6-3, a crown beam.

[ detailed description ] embodiments

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

The invention discloses a construction method for enclosure of a shallow tunnel foundation pit in a stratum with a soft upper part and a hard lower part, which comprises the following steps:

firstly, putting a slope on a shallow buried section of a tunnel and excavating to the bottom of a foundation pit of the designed shallow buried tunnel; and constructing a portal type enclosure structure 6 in the foundation pit enclosure section 1. As shown in fig. 1 and 2.

Step two, adopting a 'horse jump mouth' middle groove excavation mode for the lower part rock of the foundation pit enclosure section, and specifically comprising the following steps: divide into not hard up blasting district 2 and rock reservation district 3 with the tunnel excavation wall of foundation ditch enclosure section 1, wherein: the loosening blasting area 2 is rock distributed left and right in the 1/3B span range along the central line a of the single tunnel, and the area between the outer side of the loosening blasting area 2 and the enclosure piles of the enclosure structure is a rock reserved area 3; wherein: and B is the excavation width of the single tunnel. As shown in fig. 3.

And step three, longitudinally excavating a section of rock in the loosening blasting area 2. Each section is 6m in the sectional construction.

Step four, longitudinally cutting the inner sides of the fender posts which are respectively positioned at the same side in the rock reserved areas 3 at the left side and the right side to form a cutting line 4; the distance of one longitudinal cutting is equal to the distance of one excavation of the loosening blasting area section; the side of the cutting line 4 close to the fender pile on the same side is a weak splitting area 3-2, and the side of the cutting line far away from the fender pile on the same side is a strong splitting area 3-1.

Fifthly, firstly, carrying out one-section excavation construction on the strong splitting area 3-1 at one side, and then carrying out one-section excavation construction on the weak splitting area 3-2 at the same side; and (5) repeatedly carrying out excavation construction on the other side to finish the excavation of a section of rock in the span range of the single tunnel.

And sixthly, constructing an inverted arch in the tunnel of the excavated section, connecting the inverted arch with a guard post of the enclosure structure, forming a space with the enclosure structure, backfilling the tunnel pavement in the space to the elevation, and reserving a blasting operation space in the space.

And seventhly, repeating the third step and the sixth step to finish the excavation of the whole tunnel. Repeating the third step and the seventh step to complete the construction of the enclosure section structure of the foundation pit of the other shallow tunnel;

when cutting, the cutting depth of the cutting line exceeds the outer side line of the inverted arch. The distance between each cutting line 4 and the fender pile on the same side is 1 m.

And in the weak splitting area, a handheld hydraulic splitter is adopted for construction. And in the strong splitting area 3-1, an onboard large-scale rock splitter is adopted for construction.

In the loose blasting area 2, the arrangement boundaries of the middle groove excavation blast holes 5 are as follows: the upper surface is positioned on the surface of the bedrock, and the lower surface is positioned at the outer side line of the inverted arch.

Construction is carried out at a certain place, and the concrete steps are as follows:

(1) slope excavation is carried out on a shallow buried section of the tunnel, then two rows of fender posts 6-1 of a single shallow buried tunnel are constructed, and the depth of a pile foundation entering bedrock is not less than 3 m.

(2) And 6-3, pouring reinforced concrete crown beams at the tops of the two rows of fender piles.

(3) And a reinforced concrete cross brace is supported at the crown beam 6-3, so that the whole enclosure structure 6 forms a portal structure, as shown in fig. 4.

(4) And (3) mechanically excavating the soil body on the upper part of the foundation pit support section 1 to the bottom of the foundation pit of the designed shallow-buried tunnel, namely exposing the bedrock surface.

(5) Adopt "jump horse mouth" middle groove excavation mode when foundation ditch enclosure section 1 lower part rock excavation, specifically do: divide into not hard up blasting district 2 and reserve 3 for the rock with the tunnel excavation wall of foundation ditch enclosure section 1, wherein: the loosening blasting area 2 is rock distributed left and right in the 1/3B span range along the central line a of the single tunnel, and the area between the outer side of the loosening blasting area 2 and the enclosure piles of the enclosure structure is a rock reserved area 3; wherein: and B is the excavation width of the single tunnel.

Firstly excavating by using loose blasting, excavating rocks of a first 6m section longitudinally in a loose blasting area 2, arranging cutting holes and peripheral holes every cycle with the footage of 3m, wherein the hole distance of the cutting holes is 120-150 cm, the hole distance of the peripheral holes is 90-130 cm, and the peripheral holes are adoptedThe cartridges are loaded at intervals and the cut holes are adoptedThe cartridge is loaded powder in succession, needs 2 circulation footage blasting first 6m section rocks, and the slot excavation big gun hole arranges that the boundary upper surface is the basement rock face in the not hard up blasting district, and the lower surface is invert sideline department.

(6) Due to the existence of the guard piles 6-1, the outer boundary of blasting operation is at a certain distance from the guard piles 6-1, so that unstable collapse of a foundation pit caused by breakage of the guard piles 6-1 can be prevented, and rocks beside the guard piles are alternately excavated on the left side and the right side outside the loosening blasting area 2 in a fine splitting mode.

Longitudinally cutting the inner sides of the fender posts at one time for 6m at the left side and the right side in the rock reserved area 3 and at the same side respectively to form a cutting line 4, wherein the cutting depth exceeds the outer side line of the inverted arch; the distance of one longitudinal cutting is equal to the distance of one excavation of the loosening blasting area section; the side of the cutting line 4 close to the fender pile on the same side is a weak splitting area 3-2, and the side of the cutting line far away from the fender pile on the same side is a strong splitting area 3-1. The influence of splitting vibration wave to the fender pile during construction of strong splitting operation area can be reduced like this, then this 6m section of strong splitting operation area is under construction to the large-scale rock splitter of adoption machine-mounted, and shovel machine dress sediment transportation.

(7) The section 6m of the weak splitting area is close to the fender post 6-1, and due to the fact that the working face is narrow, a handheld hydraulic splitter with low vibration noise is adopted for operation, and a shovel machine is used for loading and transporting slag, so that the influence on vibration of the fender post 6-1 is small.

(8) And repeating the steps to construct reserved rocks at the 6m section of the side wall of the fender post at the other side in a staggered manner.

(9) After the excavation of the first 6m section of rock in the span range of the single tunnel is finished, particularly when the excavation reaches the outer side line of the inverted arch, the inverted arch is under an unfavorable working condition, so that the inverted arch is immediately constructed and 5m inverted arch is constructed, the inverted arch, the fender post 6-1 and the crown beam 6-3 are made into a closed space integral balance stress structure body, and the structure body is backfilled in time to ensure safety. A1 m operation space is reserved, and the next blasting operation is facilitated.

(10) And (4) constructing each 6m section of rock along the excavation direction of the tunnel by adopting the steps, constructing a 6m inverted arch after excavation is finished, backfilling in time, and reserving a 1m blasting operation space all the time.

(11) And under certain conditions, the lining structure at the upper part of each 6 m-section single-width shallow-buried tunnel can be directly constructed, or the lining structure at the upper part of the single-width tunnel can be constructed after the whole rock is excavated until the construction of the enclosure section structure of the foundation pit of the single-width shallow-buried tunnel is finished, and finally, soil is back filled above the arch ring of the tunnel.

(12) And applying the other shallow tunnel foundation pit enclosure section structure by adopting the same construction method.