阅读说明：本技术 一种富水砂层地质盾构接收端头的加固方法及加固结构 (Reinforcing method and reinforcing structure for water-rich sand layer geological shield receiving end ) 是由 张四俊 周峰 康飞 魏涛 惠海鹏 尚冰 郭文学 于 2021-07-15 设计创作，主要内容包括：本发明公开了一种富水砂层地质盾构接收端头的加固方法及加固结构,对盾构接收端头周围土体进行分层加固,首先设计水平冷冻加固方式,利用长短冷冻管配合将盾构端头周围土体冻结呈凹形结构的冷冻加固区,提高周围土体强度,起到止水作用,且有助于提高注浆或旋喷加固效果,因此在冷冻加固区上方设置三轴搅拌桩加固区,对盾构端头进行进一步的加固,以避免冷冻结束后土体中水分再次影响盾构端头的加固效果。上层的三轴搅拌桩加固区域的施工与水平冷冻加固区区域的施工相互之间不会产生影响,相比垂直冷冻加固方式加固效果更高,加固效率更高,确保盾构机安全接收。(The invention discloses a reinforcing method and a reinforcing structure for a geological shield receiving end head of a water-rich sand layer, which are used for reinforcing soil bodies around the shield receiving end head in a layering manner. The construction in the triaxial mixing pile reinforced area region on upper strata and the construction in the horizontal freezing reinforced area region can not influence each other, compare perpendicular freezing reinforced mode and consolidate the effect higher, consolidate efficiency higher, ensure that the shield constructs quick-witted safe receipt.)

1. A method for reinforcing a receiving end of a geological shield of a water-rich sand layer is characterized by comprising the following steps:

the design of the enclosure structure comprises the following steps: plain concrete is poured on the periphery of the shield receiving end to form an underground continuous wall with the periphery in a concave structure;

(II) layering reinforcement design:

implementing local freezing design in the length direction of the shield tunnel from 3-5m of the vault to 3-5m of the arch bottom in the depth direction; carrying out triaxial mixing pile reinforcement design in the length direction of the shield tunnel vault in the depth direction from the ground to 3-5 m;

s1, freezing design: a horizontal freezing pipe is arranged at the receiving end of the shield, the freezing pipe is parallel to the advancing direction of the shield, the freezing pipe is connected with an external freezing source, and a horizontal freezing reinforcement area is formed in the peripheral area of the freezing pipe;

the arrangement length of the freezing pipe positioned at the periphery of the contour line of the shield tunnel is 10-18m, and the arrangement length of the freezing pipe positioned within the contour line of the shield tunnel is 1.5-3m, so that a horizontal freezing reinforcement area with a concave section is formed;

the freezing pipes are arranged in a round shape at equal intervals and are distributed in a concentric manner at different radiuses; the distance between each freezing pipe is 700-900mm, and the distance between two freezing pipes is 800-1000 mm;

when the horizontal freezing reinforcement area meets the freezing requirement, before the shield arrives, the freezing pipe positioned in the inner side of the contour line of the shield tunnel is pulled out, the freezing pipe positioned at the periphery of the contour line of the shield tunnel continues to work for secondary freezing, the freezing is stopped after the shield machine completely passes through the reinforcement area, and the freezing pipe is completely pulled out;

s2, high-pressure jet grouting reinforcement design: a triaxial mixing pile reinforcing structure is arranged in the underground continuous wall, and a high-pressure jet grouting pile is adopted for lap joint between the enclosure structure of the underground continuous wall and the triaxial mixing pile reinforcing structure.

2. The method for reinforcing the shield receiving end head of the water-rich sand geological shield according to claim 1, wherein the depth of the underground continuous wall is 5m below the bottom of the shield tunnel.

3. The method for reinforcing the receiving end of the shield machine in the water-rich sand layer geological formation according to the claim 1, characterized in that a plurality of dewatering wells and observation wells are arranged in the range of the horizontal freezing and reinforcing area, and the end is subjected to dewatering by using the dewatering wells when the shield machine arrives.

4. The utility model provides a reinforced structure of rich water sand layer geology shield reception end, its characterized in that, including being located shield reception end outlying envelope structure (1), envelope structure (1) is the underground continuous wall of spill structure for plain concrete pouring forms, sets up triaxial stirring stake reinforced structure (2) in envelope structure's (1) inside the shield reception end sets up level freezing reinforcement area (4) level is provided with multichannel cryovial (5) in level freezing reinforcement area (4), cryovial (5) including setting up in shield tunnel contour line (6) outlying freezing long tube (7) and setting freezing nozzle stub (8) within shield tunnel contour line (6), the cross-section of level freezing reinforcement area (4) is the spill structure.

5. The reinforcing structure of the shield receiving end of the geological shield in the water-rich sand layer is characterized in that the arrangement length of the long freezing pipe (7) is 10-18m, and the arrangement length of the short freezing pipe (8) is 1.5-3 m.

6. The reinforcing structure of the receiving end of the geological shield of the water-rich sand layer as claimed in claim 4, wherein the freezing pipes (5) are arranged in a circular shape at equal intervals, and the plurality of freezing pipes (5) are concentrically distributed with different radiuses; the distance between each freezing pipe (5) is 700-900mm, and the distance between two freezing pipes (5) is 800-1000 mm.

7. The reinforcing structure of the water-rich sand layer geological shield receiving end head as claimed in claim 4, characterized in that the horizontal freezing and reinforcing area (4) is provided with 6-8 temperature monitoring points (9) for monitoring the temperature of the freezing area, 4-6 outer rings are uniformly arranged, and 1-2 inner rings and the center of a tunnel portal are respectively arranged.

8. The reinforcing structure of the water-rich sand layer geological shield receiving end head is characterized in that a high-pressure jet grouting pile (3) is adopted for overlapping between the enclosure structure (1) and the triaxial mixing pile reinforcing structure (2).

Technical Field

The invention relates to the technical field of tunnel construction, in particular to a method and a structure for reinforcing a receiving end of a geological shield of a water-rich sand layer.

Background

Along with the continuous development of urban rail transit in China, urban underground space is rapidly developed and utilized, the construction of underground tunnels enters the rush hour, shield construction has the advantages of good safety, high mechanization degree, high tunneling speed, small environmental disturbance, wide stratum adaptability and the like, and the shield construction is rapidly popularized and applied in the fields of urban rail transit, highway tunnels, municipal pipelines and the like, and shield construction is adopted in a large number of engineering constructions. In the shield construction process, the end part of the shield tunnel needs to be reinforced. The phenomenon of water inrush and leakage caused by poor reinforcing quality often occurs in a high water-rich stratum, soil mass collapse is seriously caused, and the shield starting and receiving are failed.

The traditional shield end reinforcing method has the following defects: 1, the water-rich sand-gravel layer is characterized by high water content, large permeability coefficient, large pebble strength, uneven gradation and the like, and the stratum is reinforced by adopting a rotary jet pile or grouting, so that the reinforcing effect is not ideal due to the reasons of difficult pore forming, dilution of underground water, difficult uniform slurry mixing and grouting, and the like; 2, the stratum is completely reinforced by adopting high-pressure jet grouting piles or grouting, and if the reinforcing effect is to be achieved, the investment cost is high and the economy is not high enough; 3 the water stopping and preventing effect is poor, water leakage and sand gushing are easy to occur, the risk of shield construction is increased, and the shield construction period is prolonged.

Disclosure of Invention

In view of the above problems in the prior art, an object of the present invention is to provide a method for reinforcing a receiving end of a geological shield in a water-rich sand layer.

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

a method for reinforcing a receiving end of a geological shield of a water-rich sand layer specifically comprises the following steps:

the design of the enclosure structure comprises the following steps: plain concrete is poured on the periphery of the shield receiving end to form an underground continuous wall with the periphery in a concave structure;

(II) layering reinforcement design:

implementing local freezing design in the length direction of the shield tunnel from 3-5m of the vault to 3-5m of the arch bottom in the depth direction; carrying out triaxial mixing pile reinforcement design in the length direction of the shield tunnel vault in the depth direction from the ground to 3-5 m;

s1, freezing design: a horizontal freezing pipe is arranged at the receiving end of the shield, the freezing pipe is parallel to the advancing direction of the shield, the freezing pipe is connected with an external freezing source, and a horizontal freezing reinforcement area is formed in the peripheral area of the freezing pipe;

the arrangement length of the freezing pipe positioned at the periphery of the contour line of the shield tunnel is 10-18m, and the arrangement length of the freezing pipe positioned within the contour line of the shield tunnel is 1.5-3m, so that a horizontal freezing reinforcement area with a concave section is formed;

the freezing pipes are arranged in a round shape at equal intervals and are distributed in a concentric manner at different radiuses; the distance between each freezing pipe is 700-900mm, and the distance between two freezing pipes is 800-1000 mm;

when the horizontal freezing reinforcement area meets the freezing requirement, before the shield arrives, the freezing pipe positioned in the inner side of the contour line of the shield tunnel is pulled out, the freezing pipe positioned at the periphery of the contour line of the shield tunnel continues to work for secondary freezing, the freezing is stopped after the shield machine completely passes through the reinforcement area, and the freezing pipe is completely pulled out;

s2, high-pressure jet grouting reinforcement design: a triaxial mixing pile reinforcing structure is arranged in the underground continuous wall, and a high-pressure jet grouting pile is adopted for lap joint between the enclosure structure of the underground continuous wall and the triaxial mixing pile reinforcing structure.

Further, the depth of the underground continuous wall is 5m below the bottom of the shield tunnel.

Furthermore, a plurality of dewatering wells and observation wells are arranged in the range of the horizontal freezing and reinforcing area, and when the shield machine arrives, the ends are dewatered by utilizing the dewatering wells.

The invention also provides a reinforced structure of the geological shield receiving end of the water-rich sand layer, which comprises an enclosure structure positioned at the periphery of the shield receiving end, wherein the enclosure structure is an underground continuous wall which is formed by pouring plain concrete and is in a concave structure, a triaxial mixing pile reinforced structure is arranged in the enclosure structure, a horizontal freezing reinforced area is arranged at the shield receiving end, a plurality of freezing pipes are horizontally arranged in the horizontal freezing reinforced area, each freezing pipe comprises a long freezing pipe arranged at the periphery of the shield tunnel contour line and a short freezing pipe arranged in the shield tunnel contour line, and the section of the horizontal freezing reinforced area is in a concave structure.

Further, the arrangement length of the long freezing pipes is 10-18m, and the arrangement length of the short freezing pipes is 1.5-3 m.

Furthermore, the freezing pipes are arranged in a circular shape at equal intervals, and the plurality of freezing pipes are concentrically distributed at different radiuses; the distance between each freezing pipe is 700-900mm, and the distance between two freezing pipes is 800-1000 mm.

Furthermore, temperature monitoring points are arranged in the horizontal freezing and reinforcing area to monitor the temperature of the freezing area, the number of the temperature monitoring points is 6-8, 4-6 outer rings are uniformly distributed, and 1-2 middle rings and inner rings and the center of the tunnel door are respectively distributed.

And further, a high-pressure jet grouting pile is adopted for lap joint between the envelope structure and the triaxial mixing pile reinforcing structure.

Compared with the prior art, the invention has the following advantages:

according to the method, the soil body around the shield receiving end is reinforced in a layering mode, firstly, a horizontal freezing and reinforcing mode is designed, the soil body around the shield receiving end is frozen into a freezing and reinforcing area in a concave structure by matching long and short freezing pipes, the strength of the surrounding soil body is improved, a water stopping effect is achieved, and the grouting or jet grouting reinforcing effect is improved.

The soil around the end is received to the shield structure is consolidated in the layering, and the regional construction of freezing the regional construction of consolidating with the level of the triaxial mixing pile in upper strata can not exert an influence each other, compares perpendicular freezing reinforcement mode and consolidates the effect higher, and it is higher to consolidate efficiency, ensures that the shield constructs quick-witted safety and receives.

The shield machine can directly break frozen soil around the freezing short pipe to form a tunnel portal, reduces the risk of stratum instability caused by manual pile breaking in advance, has small disturbance to the surrounding environment, has good waterproof effect, and greatly reduces the danger caused by water gushing and sand gushing when the shield end is received.

Drawings

FIG. 1 is a plan view of a water-rich sand geological shield receiving end reinforcing structure according to the invention;

FIG. 2 is an elevation view of a water-rich sand geological shield receiving end reinforcing structure according to the invention;

FIG. 3 is a schematic diagram of the distribution structure of the freezing pipe according to the present invention.

The device comprises an enclosure structure 1, a triaxial mixing pile reinforcing structure 2, a high-pressure jet grouting pile 3, a horizontal freezing reinforcing area 4, a freezing pipe 5, a shield tunnel contour line 6, a freezing long pipe 7, a freezing short pipe 8 and a temperature monitoring point 9.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

As shown in fig. 1-3, a reinforced structure of rich water sand layer geological shield receiving end, including being located shield receiving end outlying envelope 1, envelope 1 is the underground continuous wall that is the spill structure that plain concrete pouring formed, sets up triaxial stirring stake reinforced structure 2 in envelope 1's inside shield receiving end sets up horizontal freezing reinforced area 4 the horizontal freezing reinforced area 4 is provided with multichannel cryovial 5, cryovial 5 is including setting up at shield tunnel profile line 6 outlying freezing long tube 7 and setting up the freezing nozzle stub 8 within shield tunnel profile line 6, the cross-section of horizontal freezing reinforced area 4 is the spill structure.

According to the method, the soil body around the shield receiving end is reinforced in a layering mode, firstly, a horizontal freezing and reinforcing mode is designed, the freezing long pipe 7 arranged on the periphery of the shield tunnel contour line 6 is matched with the freezing short pipe 8 arranged in the shield tunnel contour line 6 to freeze the soil body around the shield end into the freezing and reinforcing area 4 in a concave structure, the strength of the surrounding soil body is improved, a water stopping effect is achieved, and the grouting or rotary spraying reinforcing effect is improved, so that the triaxial mixing pile reinforcing area 2 is arranged above the freezing and reinforcing area 4 to further reinforce the shield end, and the problem that the reinforcing effect of the shield end is influenced again by moisture in the soil body after freezing is finished is avoided.

The soil around the end is received to the shield structure is consolidated in the layering, and the construction of the triaxial mixing pile reinforcing area 2 on upper strata can not influence each other with the construction that 4 regions were consolidated in the freezing of level, compares perpendicular freezing reinforcement mode and consolidates the effect higher, and it is higher to consolidate efficiency, ensures that the shield constructs quick-witted safe receipt.

The shield machine can directly break the frozen soil around the freezing short pipe 8 to form a tunnel portal, reduces the risk of stratum instability caused by manual pile breaking in advance, has small disturbance to the surrounding environment, has good waterproof effect, and greatly reduces the danger caused by water gushing and sand gushing when the shield end is received.

In the embodiment, the arrangement length of the long freezing pipe 7 is 10-18m, and the arrangement length of the short freezing pipes 8 is 1.5-3 m.

As shown in fig. 3, in this embodiment, the freezing pipes 5 are arranged in a circle at equal intervals, and the plurality of freezing pipes 5 are concentrically arranged with different radii; the distance between each freezing pipe 5 is 800mm, and the distance between two freezing pipes 5 is 800 mm.

As shown in fig. 3, in the present embodiment, the horizontal freezing and reinforcing area 4 is provided with temperature monitoring points 9 for monitoring the temperature of the freezing area, the number of the temperature monitoring points is 6-8, the outer ring is uniformly arranged 4-6, and 1-2 are respectively arranged between the middle ring and the inner ring and between the inner ring and the center of the tunnel door.

As shown in fig. 2, a high-pressure jet grouting pile 3 is adopted for overlapping between the building envelope 1 and the triaxial mixing pile reinforcing structure 2. The soil body strength is improved, and the reinforcing effect is improved.

Example 2

A method for reinforcing a receiving end of a geological shield of a water-rich sand layer specifically comprises the following steps:

the design of the enclosure structure comprises the following steps: plain concrete is poured on the periphery of the shield receiving end to form an underground continuous wall with the periphery in a concave structure;

(II) layering reinforcement design:

implementing local freezing design in the length direction of the shield tunnel from 3-5m of the vault to 3-5m of the arch bottom in the depth direction; carrying out triaxial mixing pile reinforcement design in the length direction of the shield tunnel vault in the depth direction from the ground to 3-5 m;

s1, freezing design: a horizontal freezing pipe is arranged at the receiving end of the shield, the freezing pipe is parallel to the advancing direction of the shield, the freezing pipe is connected with an external freezing source, and a horizontal freezing reinforcement area is formed in the peripheral area of the freezing pipe;

the arrangement length of the freezing pipe positioned at the periphery of the contour line of the shield tunnel is 10-18m, and the arrangement length of the freezing pipe positioned within the contour line of the shield tunnel is 1.5-3m, so that a horizontal freezing reinforcement area with a concave section is formed; so that an effective water-proof environment is formed behind the front shield tail of the shield cutter head when the middle part of the freezing and reinforcing area is not broken by the shield cutter head. The design requirement of the average temperature of the freezing and reinforcing area is less than or equal to minus 10 ℃, the design requirement of the average temperature of the shield segment and frozen soil interface is less than or equal to minus 5 ℃, and the design freezing days are not less than 30 days.

The freezing pipes are arranged in a round shape at equal intervals and are distributed in a concentric manner at different radiuses; the distance between each freezing pipe is 700-900mm, and the distance between two freezing pipes is 800-1000 mm;

when the shield machine is pushed to the freezing reinforced area region and the cutter head does not reach the reinforced area region, the shield machine firstly stops to check and installs a steam generator, and the shield machine is pushed continuously after trial, at the moment, the horizontal freezing reinforced area reaches the freezing requirement, the freezing short pipe 8 positioned in the contour line of the shield tunnel is pulled out, and the freezing long pipe 7 positioned on the periphery of the contour line of the shield tunnel continues to work for secondary freezing.

When the shield machine is pushed to the horizontal freezing and reinforcing area, frozen soil around the freezing short pipe 8 can be directly broken to form a tunnel portal, the risk of stratum instability caused by manual pile breaking in advance is reduced, and disturbance to the surrounding environment is small.

The propelling speed is controlled to be 1cm/min, the temperature of the residue soil is observed at any time, the temperature of the discharged residue soil is lower than 0 ℃, and a steam generator is started immediately to prevent the cutter head from being locked by the frozen soil; at the moment, when the duct pieces are assembled, the shield tunneling machine is switched to a propulsion mode, after a cutter head of the shield tunneling machine pushes out the frozen body, a shield tail enters a reinforcing area, and synchronous grouting slurry is changed into cement mortar; stopping synchronous grouting after the tail of the shield tunneling machine is separated from the tunnel door; when the shield cutter head tunnels to a position 0.3-0.5m away from the underground continuous wall, the tunneling speed is controlled at 5mm/min, the tunneling pressure is controlled at 0.3MPa, the torque is kept at 7 multiplied by 103 and 104 kN.m, the rotation speed of the cutter head is 0.9rpm, the water pressure of a notch is 0, the shield enters by the pushing force of the shield top, the tunnel door is sealed after the shield tail is pushed out, the freezing is stopped after the shield machine completely passes through the reinforcing area, and the freezing pipe is completely removed.

S2, high-pressure jet grouting reinforcement design: a triaxial mixing pile reinforcing structure is arranged in the underground continuous wall, and a high-pressure jet grouting pile is adopted for lap joint between the enclosure structure of the underground continuous wall and the triaxial mixing pile reinforcing structure.

And the depth of the underground continuous wall is 5m below the bottom of the shield tunnel.

A plurality of dewatering wells and observation wells are arranged in the range of the horizontal freezing and reinforcing area, and when the shield machine arrives, the ends are dewatered by the dewatering wells.

The dewatering well is arranged in the soil body reinforcing area, moisture in the soil body is drained, the water content of the soil body in the reinforcing range can be effectively reduced, and the soil body strength of the shield end can be effectively improved.

The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are merely illustrative of the principles of the invention, but that various changes and modifications may be made without departing from the spirit and scope of the invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.