WO2022100346A1

WO2022100346A1 - Reinforcement structure for entry and exit of large-diameter jacking pipe group in water-rich sand stratum, and construction method

Info

Publication number: WO2022100346A1
Application number: PCT/CN2021/123555
Authority: WO
Inventors: 杨俊峰; 安刚建; 余世祥; 袁正璞; 曹广勇; 杨祖兵; 林键; 詹杰; 沃云舟; 王伟超; 邓文杰; 张挺
Original assignee: 中铁四局集团第四工程有限公司; 中铁四局集团有限公司; 安徽建筑大学
Priority date: 2020-11-10
Filing date: 2021-10-13
Publication date: 2022-05-19
Also published as: CN112253162A; CN112253162B

Abstract

A reinforcement structure for entry and exit of a large-diameter jacking pipe group in a water-rich sand stratum, and a construction method. The structure comprises underground diaphragm walls (2) and high-pressure jet grouting piles (5); the underground diaphragm walls (2) are arranged at edge positions of a launch shaft (9) and a reception shaft (10); the depths of the underground diaphragm walls (2) are below a bottom elevation of a pipe jacking machine; bored piles (4) are provided at the middles on the insides of the launch shaft (9) and the reception shaft (10); the depths of the bored piles (4) are the same as those of the underground diaphragm walls (2); cross braces (3) are used between the underground diaphragm walls (2) for support; the cross braces (3) are fixedly connected to the bored piles (4); the high-pressure jet grouting piles (5) are provided at the entry and exit of a jacking pipe group and the outside of the underground diaphragm walls (2); the high-pressure jet grouting piles (5) are arranged in row-shaped structure engaged in a quincuncial manner, and are arranged in parallel with the underground diaphragm walls (2). By performing reinforcement treatment on the entry and exit of a large-diameter jacking pipe group, the reinforcement efficiency of entry and exit openings is improved, machining process steps are simplified, and the quality of stratum reinforcement is improved, and construction difficulty and construction costs are reduced.

Description

A kind of reinforcement structure and construction method of large-diameter pipe jacking group inlet and outlet holes in water-rich sand layer

technical field

The invention relates to the technical field of multi-row pipe jacking construction, in particular to a reinforcement structure and a construction method for the entry and exit holes of large-diameter pipe jacking groups in a water-rich sand layer.

Background technique

With the continuous progress of urbanization, the application of pipe jacking in the urban pipe network is becoming more and more extensive and systematic. For areas with water-rich sand layers, large-diameter pipe jacking groups often experience engineering quality problems during the process of pipe jacking in and out of the hole. defects, etc. As a mechanically unstable stratum, the water-rich sand layer has high stratum fluidity and is easy to cause large-scale stratum disturbance. During construction, the surface subsidence is not easy to control. When the large diameter pipe jacking group enters and exits the tunnel, the construction risk is high. key process. Therefore, the reinforcement of the entry and exit holes of the large diameter pipe jacking group is one of the difficulties in the project, and the reinforcement method of the entry and exit holes is particularly important.

Pipe jacking construction in water-rich sand layer areas often causes seepage, piping, and soil flow at the entrance and exit of the tunnel. In severe cases, it may even cause soil instability and collapse of foundation pits. Reinforcement is an important part of the pipe jacking initiation and receiving technology, which refers to the reinforcement of the stratum where the pipe jacking machine enters and exits the working well. The main purposes of reinforcement are: to improve the soil strength in the working well area, to control the surface subsidence; to prevent piping and soil flow caused by seepage; to improve the bearing capacity of the soil at the end of the tunnel. In general soft soil layers, reinforcement techniques such as deep stirring piles and freezing methods are often used. When the geological conditions are complex, the conventional stirring pile reinforcement technology is difficult to form piles under complex geological conditions; the construction cost of the freezing method is too high, the construction is difficult and the construction period is long.

In view of the above-mentioned defects, the creator of the present invention finally obtained the present invention after a long period of research and practice.

SUMMARY OF THE INVENTION

In order to solve the above-mentioned technical defects, the technical solution adopted in the present invention is to provide a reinforcement structure for the entrance and exit of the large-diameter pipe jacking group in the water-rich sand layer, including an underground diaphragm wall and a high-pressure rotary jet pile, and the underground diaphragm wall is arranged at the starting point. At the edge positions of the well and the receiving well, the depth of the underground diaphragm wall is below the bottom elevation of the pipe jacking machine, and a bored cast-in-place pile is arranged in the middle of the inner side of the originating well and the receiving well, and the bored cast-in-place pile is connected with all the boreholes. The underground diaphragm walls are of the same depth, and cross braces are used between the underground diaphragm walls; the cross braces are fixedly connected to the bored cast-in-place piles; On the outer side of the diaphragm wall, the high-pressure jetting piles are arranged in two rows of plum-like occlusion, which are arranged in parallel with the underground continuous wall, and are spaced from the underground continuous wall, and the depth of the high-pressure jetting piles exceeds the jacking pipe. The bottom of the machine, the width along the underground diaphragm wall beyond the pipe jacking machine.

Preferably, the thickness of the underground diaphragm wall is 0.8m.

Preferably, the surface soil layer in front of the inlet and outlet holes of the pipe jacking group is reinforced and hardened, and a dewatering well is evenly arranged on the outside of the high-pressure jetting pile and the underground diaphragm wall.

Preferably, the buried depth of the underground diaphragm wall exceeds the elevation of the bottom of the pipe jacking machine group by 10m.

Preferably, the width of the high-pressure jetting pile group exceeds half the width of the pipe jacking machine, and the depth of the high-pressure jetting pile is 5m beyond the bottom of the pipe jacking machine.

Preferably, the height of the high-pressure jetting pile exceeds twice the elevation of the pipe jacking machine, and the distance from the underground diaphragm wall is 0.5m.

Preferably, a construction method for the reinforcement structure of the entry and exit holes of the large-diameter pipe jacking group in the water-rich sand layer, comprising the steps of:

S1, determine the reinforcement requirements and areas;

S2, surface reinforcement treatment;

S3, reinforcement treatment in the working well;

S4, the end of the jacking pipe inlet and outlet holes is reinforced.

S5, pipe jacking in and out quality control.

Preferably, in step S2, the dewatering wells are evenly and symmetrically arranged along the groundwater flow potential at the edge of the field area, and the depth of the dewatering wells is 2m below the bottom of the tunnel where the pipe jacking machine is jacked.

Preferably, after the dewatering well is installed, the surface is leveled, the field area is cleaned and the surface is grouted and hardened for reinforcement, and the grouting adopts cement single grout.

Preferably, in step S3, the construction of the underground diaphragm wall is carried out on the outer edge of the working well, and after the construction of the underground diaphragm wall is completed, the bored piles are symmetrically constructed in the center of the interior of the working well, and the drilling The cast-in-place pile is made of mud wall to form holes, and then the excavation of the working well is carried out in the way of three-sequence formation of grooves. The horizontal brace is constructed, and the bottom plate of the working well is constructed.

Preferably, in step S5, a water stop ring is set at the entrance of the inlet and outlet holes of the jacking pipe group, and the water stop ring is embedded in the lining structure and the enclosure structure, and the enclosure structure is an underground continuous wall, so The inner lining structure is a concrete reinforcement structure extending from the underground diaphragm wall to the working well; the water stop ring includes a pre-embedded steel ring, a pressure plate, a rubber ring and an installation steel ring, and the pressure plate and the rubber ring are arranged on the pre-buried steel ring. Between the embedded steel ring and the installation steel ring, when the enclosure structure is set, the embedded steel ring is pre-embedded. The inner diameter of the ring is the same size as the reserved hole; an annular reinforced concrete protection ring is arranged in the embedded steel ring, the rubber ring is arranged on one side of the working well, and the rubber ring is pressed by the pressing plate .

Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention performs reinforcement treatment on the inlet and outlet holes of the large-diameter pipe jacking group, which not only improves the reinforcement efficiency of the inlet and outlet holes, simplifies the processing steps, but also greatly improves the quality of the stratum reinforcement and the construction. The difficulty and construction cost are reduced, which ensures the construction period, quality and economy of the project.

Description of drawings

Fig. 1 is the structural view of described water-rich sand layer large diameter pipe jacking group in and out hole reinforcement structure;

Figure 2 is a structural view of the originating well;

Fig. 3 is the plum-blossom occlusal structure diagram of described high-pressure rotary jet pile;

Fig. 4 is the reinforcement structure diagram of the pipe jacking inlet and outlet holes;

FIG. 5 is a flow chart of the construction method for the reinforcement structure of the large diameter pipe jacking group in and out of the water-rich sand layer.

The numbers in the figure represent:

1- Dewatering well; 2- Underground diaphragm wall; 3- Cross brace; 4- Bored cast-in-place pile; 5- High pressure rotary jetting pile; 6- The first entrance; ; 9- originating well; 10- receiving well; 11- bottom plate of working well; 12- opening; 13- lining structure; 14- enclosure structure; 15- embedded steel ring; 16- annular reinforced concrete protection ring; 17-Reinforced soil; 18-Installation steel ring; 19-Press plate; 20-Rubber ring; 61-The first outlet; 71-The second outlet; 81-The third outlet.

Detailed ways

The above and other technical features and advantages of the present invention will be described in more detail below with reference to the accompanying drawings.

Example 1

The reinforcement structure for the inlet and outlet holes of the large-diameter pipe jacking group in the water-rich sand layer according to the present invention includes an underground diaphragm wall and a high-pressure rotary jet pile. The thickness of the wall is 0.8m, the depth of the underground diaphragm wall is 10m below the bottom elevation of the pipe jacking machine, so as to effectively form a water-stop curtain, and the corresponding underground diaphragm wall is supported by transverse braces.

Preferably, a row of two C30 bored cast-in-place piles with a diameter of 0.6 m are arranged in the middle of the inner side of the originating well and the receiving well, and the bored cast-in-place piles are at the same depth as the underground diaphragm wall, both of which are in the same depth. Below the elevation of the bottom of the pipe jacking machine is 10m, the cross brace is fixedly connected with the bored pile, so that the cross brace in the support well is reinforced by the bored pile.

The high-pressure jetting piles are arranged at the entrance and exit holes of the pipe jacking group and the outside of the underground continuous wall. The diameter of a single high-pressure jetting pile is 0.6m, and is generally arranged in two rows of plum blossoms, which are continuous with the underground. The walls are arranged in parallel, and the distance from the underground diaphragm wall is set to 0.5m, the depth of the high-pressure rotary jet pile is 5m beyond the bottom of the pipe jacking machine, and the width is 2m beyond the pipe jacking machine along the underground diaphragm wall.

Preferably, the surface soil layer in front of the inlet and outlet holes of the pipe jacking group is reinforced and hardened, and a dewatering well with a diameter of 1.6m is evenly arranged on the outside of the high-pressure jetted pile and the underground diaphragm wall for drainage and foundation pits. The excavation depth is 12m. In order to effectively achieve the dewatering effect of the water-rich sand layer, the depth of the dewatering well is 10m beyond the bottom of the pit.

The reinforcement structure of the large diameter pipe jacking group in and out of the water-rich sand layer according to the invention is a kind of pipe jacking construction tunnel suitable for the water-rich sand layer. Mainly use dewatering wells, high-pressure rotary jet engagement piles, underground diaphragm walls and other systems to reinforce the soil in the interval between the pipe-jacking originating well and the receiving well, so as to realize the reinforcement method of the pipe-jacking machine group entering and exiting the hole in the water-rich sand layer. The front end of the originating well and the rear outer edge of the receiving well are reinforced through the high-pressure rotary jet clinching pile and the enclosure structure of the working well to form a dense, continuous and rigid support system, and a dewatering well is used as an enclosure. Protects and stops water. The high-pressure rotary jet occlusal piles added on the outside can effectively make up for the problems of soil erosion and stratum instability caused by the pipe jacking machine group during the opening and jacking process. The diameter of the pipe jacking machine is 3.5m, and it penetrates the water-rich sand layer. The method of the invention not only improves the reinforcement efficiency of the entrance and exit holes, simplifies the processing steps, but also greatly improves the quality of formation reinforcement, construction safety, construction difficulty and construction. The cost is reduced, and it can meet the construction of pipe jacking machine groups in different strata.

Embodiment 2

As shown in Fig. 1, Fig. 1 is a structural view of the reinforcement structure of the inlet and outlet holes of the large-diameter pipe jacking group in the water-rich sand layer; this embodiment is explained by an actual case;

The three pipe jacking machines are assembled in the starting shaft 9, and are respectively jacked from the first inlet 6, the second inlet 7, and the third inlet 8 from left to right, and then the first outlet 61, the second inlet 8 The outlet 71 and the third outlet 81 reach the receiving well.

When the pipe jacking machine group takes out the originating well 9, it is called the exit hole, and when the pipe jacking machine group enters the receiving well 10, it is called the entrance hole, thus completing a cycle.

As shown in Fig. 2, Fig. 2 is a structural view of the originating well; The soil layer is reinforced, and the support 3 and the bored cast-in-place pile 4 are applied to the working well, namely the originating well 9 and the receiving well 10, to reinforce the underground diaphragm wall 2 in the well. A working well bottom plate 11 is provided at the bottom of the underground diaphragm wall 2 , and the underground diaphragm wall 2 , the high-pressure rotary jetting pile 5 and the bored cast-in-place pile 4 are all deep below the working well bottom plate 11 .

The diameter of the dewatering well 1 is 1.6m, and it is evenly arranged along the working well.

As shown in Fig. 3, Fig. 3 is a plum-shaped occlusal structure diagram of the high-pressure rotary jetting pile; 2. The top entrances are arranged side by side, and the distance between a row of high-pressure rotary jet piles 5 close to the underground diaphragm wall 2 is 0.5m. The grouting material is ordinary silicon 42.5 cement, cement slurry (single liquid), and the water-cement ratio is 1:1 impermeable slurry, so that the entire formation can be effectively reinforced, forming a compact whole with the underground diaphragm wall 2 to prevent piping and seepage when the originating well 9 and the receiving well 10 are broken.

At the same time, the cement dosage of the high-pressure rotary jet pile 5 is controlled to be less than the cement dosage of the underground diaphragm wall 2, so as to ensure that the strength of the reinforced soil is between 1.2 MPa and 1.5 MPa, which can ensure the normal jacking of the pipe jacking machine group and avoid the top It is difficult to break the pile into the cutter head.

The depth of the underground diaphragm wall 2 is twice the elevation of the bottom of the pipe jacking machine group, which can well form a water-stop curtain and prevent the base from surging.

The cross braces 3 in the originating well 9 and the receiving well 10 are reinforced concrete structures, which play a supporting role for the underground diaphragm wall and resist the earth pressure. The cross braces 3 are mainly poured from the borehole. The pile 4 is used for load bearing and stability maintenance, and its combined support system can also be used for the lifting and installation of the pipe jacking equipment.

Dewatering wells 1 are arranged in the outer edge soil layers of the originating well 9 and the receiving well 10 along the direction of groundwater flow potential to conduct well point dewatering, enhance soil strength, and improve the airtightness of the cave door.

On the edges of the originating well 9 and the receiving well 10, an underground diaphragm wall method is used to form the enclosure structure. The thickness of the underground diaphragm wall 2 is 0.8m, and the depth of soil penetration is twice the elevation of the bottom of the pipe jacking machine group. The water-stop curtain effectively prevents water and soil seepage from entering the originating well 9 and the receiving well 10 . A ring beam with a section size of 1m*0.8m is made on the top of the diaphragm wall, so that the diaphragm wall can form a whole. The joint form of underground diaphragm wall adopts rigid joint cross steel plate for joint.

After the construction of the surrounding underground diaphragm walls of the originating well 9 and the receiving well 10 is completed, the internal cross braces 3 and bored cast-in-place piles 4 are constructed. The cross braces 3 are used to maintain the stability of the working well and prevent external The underground diaphragm wall 2 caused by the earth pressure is deformed inward to prevent collapse. The diameter of the bored pile 4 is 0.6m, and ordinary Portland cement above grade 42.5 and C30 concrete are used for the load-bearing of the cross braces and the lifting equipment in the originating well 9 and the receiving well 10 .

The soil layer between the front end of the originating well 9, that is, the side where the pipe jacking machine group exits the hole, and the front end of the receiving well 10, that is, the side where the pipe jacking machine group enters the hole, is reinforced. The surface of the reinforcement area is hardened, and the high-pressure rotary jet pile method is used for formation reinforcement and water isolation. Ordinary Portland cement of grade 42.5 or above is used, and the grade is C20. The high-pressure jetting piles are separated by 0.5m from the underground diaphragm wall on the exit side of the originating well and the underground diaphragm wall on the entrance side of the receiving well. The depth of the jetting pile group exceeds twice the elevation of the pipe jacking machine, and can pass through the permeable layer. During the construction of the high-pressure jetting pile, it can effectively form a dense whole with the underground diaphragm wall.

Embodiment 3

As shown in FIG. 4, FIG. 4 is a reinforcement structure diagram of the inlet and outlet holes of the jacking pipe, the hole 12 is provided with a water stop ring, and the hole 12 is the hole of the inlet and outlet holes of the jacking pipe group. Embedded in an inner lining structure 13 and an enclosure structure 14, the enclosure structure 14 is an underground diaphragm wall, and the inner lining structure 13 is a concrete reinforcement structure extending from the underground diaphragm wall to the working well. The reinforced soil body 17 in the figure may be the high-pressure jetted pile 5 .

The water stop ring includes a pre-embedded steel ring 15, a pressure plate 19, a rubber ring 20 and an installation steel ring 18. The pressure plate 19 and the rubber ring 20 are arranged on the pre-embedded steel ring 15 and the installation steel ring 18. In between, when the enclosure structure 14 is set, the pre-embedded steel ring 15 is pre-embedded, and a reserved hole is formed after the inside of the pre-embedded steel ring 15 is chiseled, and the inner diameter of the pre-embedded steel ring is the same as the reserved hole. The hole is the same size. When the length of the water stop ring is long, an annular reinforced concrete protection ring 16 may also be arranged in the embedded steel ring 15, and the annular reinforced concrete protection ring 16 is used to replace part of the rubber ring 20. The rubber ring 20 is arranged on one side of the working well, and the rubber ring 20 is pressed by the pressing plate 19 to ensure a good sealing effect between the embedded steel ring 15 and the installation steel ring 18 .

In order to make the pre-embedded steel ring 15 firmly pre-embedded on the wall of the hole, several split anchor rods are welded on the side where it is in contact with the concrete, which is mainly to facilitate the removal of the ground connecting wall when the pipe jacking machine exits the hole. The hole door is firmly connected to the upper structure of the wall, so that other parts are not affected by the removal of the hole door; several bolts are welded on the installation steel ring 18 to install the rubber ring 20 and the pressure plate 19. The pressing plate 19 is used to fix the position of the rubber ring 20 to prevent it from being deformed and displaced.

Preferably, a clamping structure is provided at the connection position of the rubber ring 20 and the annular reinforced concrete protection ring 16 , and the connection between the rubber ring 20 and the annular reinforced concrete protection ring 16 is realized through the clamping structure. The rubber ring 20 is placed at the door of the hole, and due to its elastic expansion characteristics, it can better seal the pipe joint and the upper structure to prevent water seepage.

Embodiment 4

As shown in Figure 5, Figure 5 is a flowchart of the construction method of the water-rich sand layer large-diameter pipe jacking group in-out hole reinforcement structure; the construction of the water-rich sand layer large-diameter pipe group in-out hole reinforcement structure method, including the following steps:

S1, determine the reinforcement requirements and areas;

The local layer is a water-rich sand layer. The measured groundwater depth is 1.3 to 7.6 meters, and the water level elevation is 4.5 to 20.0 meters. The permeability coefficient of artificial plain filled soil is less than or equal to 1.00×10-5cm/s, which belongs to the medium water permeability level, so the surface of the stratum needs only simple grouting and hardening treatment. The bottom silt, medium sand, strongly weathered basalt and coarse sand layers have a permeability coefficient k of 1.10×10-2cm/s≤k≤1.08×10-3cm/s, which are highly permeable layers with poor hydraulic properties. Seepage deformation stability is a relatively unstable soil layer, which is prone to seepage deformation, so the reinforcement requirements are higher, and the soil should form a dense and continuous soil layer without flow-plastic phenomenon. Determine the stratum reinforcement requirements according to the design requirements to ensure the stability of the stratum.

The diameter of the pipe jacking machine is 3.5m. Considering the hoisting and installation of the pipe jacking machine group and the production of the jacking back, the excavation design of the working well is as follows: the working well is 24.1m long and 11.4m wide. area reinforcement.

S2, surface reinforcement treatment;

First of all, a dewatering well with a diameter of 1.6m is set up uniformly and symmetrically along the groundwater flow potential at the edge of the field area. The design standard value only needs to dewater the pit bottom to less than 0.5m. For sand, coarse sand, silty clay and strongly weathered basalt, the depth of the dewatering well is 10m below the bottom of the tunnel where the pipe jacking machine is jacked.

Then, the surface is leveled, and the field area is cleaned and hardened by grouting on the surface for reinforcement. The grouting adopts cement single grout, and the field materials and access equipment are provided according to the design requirements.

S3, reinforcement treatment in the working well;

The working well is 24.1m long and 11.4m wide. The enclosure structure adopts the underground diaphragm wall + 1.0m×0.8m reinforced concrete internal support system, the diaphragm wall is 80cm wide, 8 standard "one" sections, 4 special-shaped "L" sections, the standard section width is 6m, and the special-shaped section width is 5.75m,

The outer edge of the working well adopts a 0.8m thick underground diaphragm wall. The construction of the underground diaphragm wall includes measuring and positioning according to the design drawings, lofting and drawing lines, excavation of the top foundation groove, construction of guide walls, mud wall protection system, deep trench excavation, Lower the steel cage to pour concrete and pull out the conduit. A ring beam with a section size of 1m*0.8m is made on the top of the diaphragm wall, so that the diaphragm wall can form a whole. The joint form of underground diaphragm wall adopts rigid joint cross steel plate for joint.

Then, a row of two C30 bored piles with a spacing of 6m are constructed symmetrically in the center of the working well, and the mud wall is used to form holes with a diameter of 0.6m. The mud system adopts a mud circulation system made of bentonite, and is equipped with a mud pool. The drilling is made by percussion drilling. Then carry out the excavation of the working well. The excavation adopts step-by-step excavation, and the excavation is symmetrical from both sides to the middle. The three-sequence trough is adopted. The reinforced concrete horizontal transverse bracing and horizontal longitudinal bracing are arranged at m, and the supports in this project are all permanent supports and do not involve the replacement and dismantling process. Next, the base plate structure is constructed, and the back cover is covered with a plain concrete cushion, and the pouring is completed at one time, and then the base plate is constructed with a reinforced concrete structure, and the construction joint is located 1.2m above the side wall of the base plate.

S4, the end of the jacking pipe inlet and outlet holes is reinforced;

The end of the pipe jacking inlet and outlet holes is reinforced by high-pressure jetting piles. According to the characteristics of the water-rich sand layer, the diameter and spacing of the high-pressure jetting piles are designed. The single-pipe method is used for the rotary jetting piles. The diameter of the pile is 0.6~1.0m, considering its economic rationality and the continuity of mutual overlap, the pile diameter is 0.6m, and two rows of grouting holes are used; The design value of the distance is 0.75R, so the row distance is 0.45m. Ordinary silicate 42.5 cement is used, and the water-cement ratio of cement single slurry is 1:1 to carry out synchronous grouting and follow-up grouting process, and control the grouting rate and uniformity; The plum-shaped double-row occlusal arrangement is adopted on the outside of the exit hole of the originating well and the outside of the entry hole of the receiving well. The specific arrangement is arranged according to the "Z" shape in Figure 3, and the lap joint according to the construction sequence of "a-b-c-d-e-f-g" in the figure, the occlusal lap joint can be Effectively form an overall lap; the construction of high-pressure rotary jetting piles includes measuring and laying out lines, determining hole positions, drilling holes, cleaning holes, and spraying.

In step S4, before constructing the high-pressure jetting pile, a technical test of the high-pressure jetting pile should be carried out. Parameter basis, so as to ensure the construction quality of high-pressure rotary jetting piles.

S5, install a water stop ring at the entrance of the hole. The water stop ring at the entrance is mainly composed of a pre-embedded steel ring, a pressure plate, a rubber ring and an installation steel ring. In order to make the embedded steel ring firmly embedded on the hole wall, several split anchors are welded on the side it contacts with the concrete. The inner diameter of the embedded steel ring is the same size as the reserved hole; the installation of the steel ring is Welded on the embedded steel ring, several bolts are welded on the installation steel ring to install the rubber ring and the pressure plate.

The installation position should be adjusted according to the axis position of the exit hole. Since the jacking pipe will inevitably deviate from the axis position of the exit hole, the water stop ring allows the machine head to have a 2cm axis position. If the deviation of the machine head exceeds 2cm, the water stop ring The installation position must be adjusted according to the actual deviation.

The diameter of the machine head is generally 2cm larger than the outer diameter of the pipe, so that there is a gap of 2cm between the pipe and the hole, which is easy to form a mud sleeve, which is convenient to reduce the frictional resistance between the pipe wall and the soil. The length of the pipe ring is 2.6m, so that after the first pipe ring is fully jacked, its section is at the column section in the reinforced area of the rotary jet pile.

Considering that the thickness of the underground diaphragm wall is 0.8m, the diameter of the rotary jetting pile is 0.6m, and the spacing of the second row is 0.45m, in order to prevent the phenomenon of soil flow at the entrance of the first pipe when the first pipe is broken into the hole, the length of the pipe ring is 2.6m, so that the first pipe ring is completely After jacking in, its section is at the column section in the reinforced area of the rotary jet pile.

Preferably, the buried depth of the underground diaphragm wall is 10m higher than the elevation of the bottom of the pipe jacking machine group, which can effectively form a water-stop curtain.

Preferably, the width of the high-pressure jetting pile group exceeds half of the width of the pipe jacking machine.

Preferably, the height of the high-pressure jetting pile is twice the elevation of the pipe jacking machine, and the distance from the underground diaphragm wall is 0.5m, which can be effectively combined with it to reinforce the soil layer in front of the hole.

The material used for the high-pressure rotary spray pile is cement slurry. The cement slurry is sprayed into the soil layer and mixed with the soil by high pressure through the rotating nozzle to form cement-soil solids, which overlap each other to form piles for retaining soil and water, reducing the The process of erecting temporary supports. Improve the efficiency of the pipe jacking machine entering and exiting the hole, and reduce the cost of entering and exiting the hole.

The method of the invention is used to reinforce the inlet and outlet holes of the large-diameter pipe jacking group, which not only improves the reinforcement efficiency of the inlet and outlet holes, simplifies the processing steps, but also greatly improves the quality of the stratum reinforcement, reduces the construction difficulty and construction cost, and ensures the safety of the project. Duration, quality and economy.

The above descriptions are only preferred embodiments of the present invention, which are merely illustrative rather than limiting for the present invention. Those skilled in the art understand that many changes, modifications and even equivalents can be made within the spirit and scope defined by the claims of the present invention, but all fall within the protection scope of the present invention.

Claims

A large-diameter pipe jacking in-out hole reinforcement structure in a water-rich sand layer is characterized in that it includes an underground diaphragm wall and a high-pressure rotary jet pile, the underground diaphragm wall is arranged at the edge positions of the originating well and the receiving well, and the The depth of the underground diaphragm wall is below the bottom elevation of the pipe jacking machine; bored cast-in-place piles are arranged in the middle of the inner side of the originating well and the receiving well, and the bored cast-in-place piles are at the same depth as the underground diaphragm wall, and the underground continuous The walls are supported by cross braces, and the cross braces are fixedly connected with the bored cast-in-place piles; the high-pressure jetting piles are arranged at the inlet and outlet holes of the pipe jacking group and the outside of the underground continuous wall, and the high-pressure jetting piles are arranged It is a row-like structure with a plum-like occlusion, which is arranged in parallel with the underground diaphragm wall, and is spaced from the underground diaphragm wall. Beyond the pipe jacking machine.
The large-diameter jacking pipe group access hole reinforcement structure of claim 1, wherein the thickness of the underground diaphragm wall is 0.6m to 1m.
The large-diameter pipe jacking group entry and exit hole reinforcement structure in a water-rich sand layer according to claim 1, wherein the surface soil layer in front of the pipe jacking group entrance and exit holes is reinforced and hardened, and the high-pressure rotary jetting pile and the surface soil layer are reinforced and hardened. Dewatering wells are evenly arranged on the outer side of the underground continuous wall.
The large-diameter pipe jacking group entry and exit hole reinforcement structure in a water-rich sand layer according to claim 1, wherein the buried depth of the underground diaphragm wall is 10m beyond the bottom elevation of the pipe jacking machine group.
The large-diameter pipe jacking hole reinforcement structure of claim 1, wherein the width of the high-pressure jetting pile group exceeds half the width of the pipe jacking machine, and the high-pressure jetting pile depth exceeds The bottom of the pipe jacking machine is 5m.
The large-diameter pipe jacking hole reinforcement structure of water-rich sand layer according to claim 1, characterized in that, the height of the high-pressure jetting pile exceeds twice the elevation of the pipe jacking machine, and the distance from the underground diaphragm wall is 0.5m.
A construction method for the reinforcement structure of the large diameter pipe jacking group in and out of the water-rich sand layer as described in one of claims 1-6, characterized in that, comprising the steps of:

S1, determine the reinforcement requirements and areas;

S2, surface reinforcement treatment;

S3, reinforcement treatment in the working well;

S4, the end of the jacking pipe inlet and outlet holes is reinforced.

S5, pipe jacking in and out quality control.
The construction method according to claim 7, characterized in that, in step S2, the dewatering wells are evenly and symmetrically arranged along the groundwater flow potential at the edge of the site, and the dewatering well depth is below the bottom of the tunnel where the pipe jacking machine is jacked. 10m; after the dewatering well is installed, the surface is leveled, and the field area is cleaned and the surface is grouted and hardened for reinforcement, and the grouting adopts cement single grout.
The construction method according to claim 7, characterized in that, in step S3, the construction of the underground diaphragm wall is performed on the outer edge of the working well, and after the construction of the underground diaphragm wall is completed, the construction is performed centrally symmetrically inside the working well. The bored cast-in-place piles are formed by mud retaining walls to form holes, and then the excavation of the working well is carried out by means of three-sequence formation of grooves. Excavate, set up the horizontal brace after excavating the design elevation, and construct the bottom plate of the working well.
The construction method according to claim 7, characterized in that, in step S5, a water stop ring is set at the entrance of the inlet and outlet holes of the jacking pipe group, and the water stop ring is embedded in the lining structure and the enclosure structure, so The enclosure structure is an underground diaphragm wall, and the lining structure is a concrete reinforcement structure extending from the underground diaphragm wall to the working well; the water stop ring includes a pre-embedded steel ring, a pressure plate, a rubber ring and an installation steel ring, the pressure plate and the rubber ring is arranged between the pre-embedded steel ring and the installation steel ring, when the enclosure structure is set, the pre-embedded steel ring is pre-embedded, and after the inside of the pre-embedded steel ring is chiseled A reserved hole is formed, and the inner diameter of the embedded steel ring is the same size as the reserved hole; an annular reinforced concrete protection ring is arranged in the embedded steel ring, and the rubber ring is arranged on one side of the working well and passes through all the holes. The pressing plate presses the rubber ring.